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Secondary Surgical and Neodymium-YAG Laser Discissions
Secondary Surgical and Neodymium-YAG Laser Discissions Thomas
J. Liesegang,
M.D., William M. Bourne, M.D., and Duane M. Ilstrup, M.S.
Between November 1978 and June 1984, 161 surgical and 102 neodymium-YAG laser discissions were performed. The incidence of discission in patients with a mean three-year followup after extracapsular surgery was 22.1 % (39 of 176 eyes) after extracapsular cataract extraction alone and 14.5% (81 of 558 eyes) after extracapsular cataract extraction with intraocular lens implantation (P <.02); the incidence was 25.5% (47 of 184 eyes) with the transiridectomy clip lens and 9.1% (33 of 364 eyes) with the posterior chamber lens (P <.001). The average interval between cataract surgery and the discission was 2.4 years. The intraocular pressure was increased in 51 % (48 eyes) of the eyes two to five hours after YAG laser discission and was unpredictable in most patients. After surgical discission, the intraocular pressure was increased on the first postoperative day in 13% (18 eyes) of the eyes. With surgical discission, significant complications included vitreous manipulation, wound leak, and intraocular inflammation. Intraocular lens pitting occurred in 20 patients undergoing YAG laser discission. Complications with both procedures included cystoid macular edema, retinal detachment, glaucoma, and closure of a previously adequate discission opening. THE POPULARITY of extracapsular cataract extraction has increased because of the advantages of the posterior capsule in stabilizing the Accepted for publication July 15, 1985. From the Departments of Ophthalmology (Drs. Liesegang and Bourne) and Medical Statistics and Epidemiology (Mr. Ilstrup), Mayo Clinic and Mayo Foundation, Rochester, Minnesota. This study was supported in part by research grant EY-02037 from the National Institutes of Health, by Research to Prevent Blindness, Inc., and by the Mayo Foundation. Reprint requests to Thomas J. Liesegang, M.D., Department of Ophthalmology, Mayo Clinic, Rochester, MN 55905.
510
intraocular lens implant as well as anterior and posterior segment structures. This procedure may also be associated with a lower incidence of cystoid macular edema! and aphakic retinal detachment," The main disadvantage is the high incidence of opacification of the posterior capsule. Previous treatments for a cloudy posterior capsule included polishing the capsule and surgical discission. The neodymium-YAG laser recently became available in the United States as an alternative means of rupturing the posterior capsule. We studied the Mayo Clinic experience with a consecutive series of surgical discissions and then a consecutive series of YAG laser discissions. A number of reports on YAG laser discissions have appeared.r" but there are few comparative reports on the complications of surgical discissions."" The ocular risks from the YAG laser are related to the transmitted shock, electromagnetic energy, and perhaps other effects that are presently unknown." Long-term follow-up will be necessary to evaluate the safety of this technique fully.
Subjects and Methods All cases of extracapsular cataract surgery with or without an intraocular lens implant and all secondary surgical or YAG laser discissions performed at the Mayo Clinic between Nov. 1, 1978, and June 15, 1984, were tabulated. The extracapsular extraction consisted of manual expression of the nucleus, aspiration of the cortex with a Kelman irrigation and aspiration unit, and scratching of the posterior capsule as necessary. The intraocular lenses were originally inserted under air, but since 1983 they have been inserted under sodium hyaluronate, which is removed at the completion of the procedure. Surgical discissions were all performed in the operating room under sterile conditions. The globe was fixed, a Swan knife
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passed through the corneosclerallimbus, and a vertical discission made. In November 1983, the YAG laser began to be used. Before the YAG laser discission was performed, the patient was given topical anesthesia and the pupil dilated; usually an Abraham contact lens was utilized. The least power in millijoules (one pulse per burst) capable of achieving a discission was selected and focused on the posterior capsule to accomplish a small capsulotomy. Patients were examined two and five hours after the procedure, during which time medications were not routinely administered. All patients were examined before and after cataract surgery and discission until either December 1984 or the last follow-up visit. All patients who had undergone YAG laser discission were examined in a prospective study. Endothelial cell photographs were taken with a specular microscope preoperatively and one week and six months after discission. Many of the patients with surgical discissions were being monitored as part of a continuing study on the efficacy and safety of intraocular lenses and had endothelial cell photographs taken either at regular intervals or in association with the surgical discission. We excluded from some of the statistical comparisons patients who had two discissions in the same eye but included patients who had undergone discission on both eyes by different
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techniques and patients who had undergone discission on both eyes by the same technique (although only one eye was selected at random). In tabulating the complications, however, we considered all discissions. We used the Wilcoxon rank-sum test, two-sample t-test, X2 test, and signed-rank test for statistical analysis with P <.05 considered to be significant. Between Nov. I, 1978, and June 15, 1984, a total of 3,207 extracapsular cataract extractions were performed at the Mayo Clinic. Of these 3,207 operations, 645 were extracapsular cataract extractions alone and 2,562 were extracapsular cataract extractions with placement of an intraocular lens (Fig. 1). During this same time, 263 secondary discissions were performed in 257 eyes of 239 patients. The first 161 discissions were surgical, and the last 102 discissions were performed with the neodymium-YAG laser. We have not performed a secondary surgical discission since obtaining the YAG laser in November 1983. Nineteen of the discissions were performed on eyes that had undergone cataract surgery at the Mayo Clinic before November 1978, and 35 discissions (16 surgical and 19 YAG laser) were performed on 35 eyes of patients who did not have their primary cataract surgery at the Mayo Clinic. Twelve patients had surgical discission on both eyes; two patients had YAG laser discissions in both eyes; four patients had surgical discissions in one eye and YAG laser discissions in the other eye;
200 150
.a 100 E ::J 50 Z 0
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(645) (2562)
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~Surgical discission (161) (102) OYAG discission
0 0
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J-J 1984
37 97 79 85 52 62 63 52 38 33 42 80 137 141 162 207 197 241 262 296 402 422 1 0
1 0
8 0
12 0
16 0
18 0
30 0
32 0
23 0
20 27
0 75
Fig. 1 (Liesegang, Bourne, and Ilstrup). The number of extracapsular cataract extractions (ECCE), extracapsular cataract extractions with intraocular lens implants (ECCE and 10L), surgical discissions, and YAG laser discissions performed at the Mayo Clinic between Nov. I, 1978, and June 15, 1984.
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five patients with surgical discissions later underwent closure of the discission opening. Of these, four had YAG laser discissions. Two patients with YAG laser discissions later had additional YAG laser applications to open the discission further. Transiridectomy clip implants were used between February 1979 and April 1982. We began using posterior chamber implants in April 1979 and posterior chamber implants with convex posterior surfaces in February 1982. Ultraviolet-absorbing lenses were not used. Of the 645 eyes with planned extracapsular cataract extractions performed at the Mayo Clinic, 100 had required discissions as of June 1984; of the 2,562 eyes with planned extracapsular cataract extractions and placement of intraocular lenses, 113 had required discissions as of June 1984. Of the 2,370 eyes with posterior chamber intraocular lenses, 71 required discissions. Of these posterior chamber lenses, 718 had convex posterior surfaces. Four of these eyes required discissions. Of the 192 eyes with transiridectomy clip implants after extracapsular cataract extraction, 42 required discissions. Some of these patients may subsequently have had discissions elsewhere without our knowledge. Because the follow-up periods varied greatly among these different styles of implants, we did not believe that a statistical comparison of the incidence of discission in these groups would be valid. In our ongoing intraocular lens study (entry into this study was terminated in 1982), however, the follow-up is closely monitored and is now more than three years for most patients, including 558 patients with extracapsular cataract extractions and intraocular lens implantation and 176 patients with extracapsular cata-
ract extractions alone (the control group). There was a significantly higher rate of discission in patients with extracapsular cataract extractions (39 of 76 eyes or 22.1 %) than in those with extracapsular cataract extractions and intraocular lens implants (81 of 558 eyes or 14.5%) (P <.02). Patients with posterior chamber implants had a lower rate of discission (33 of 364 eyes or 9.1%) than did patients with transiridectomy clip implants (47 of 184 eyes or 25.5%) (P <.001; Table 1). A total of 247 eyes (153 surgical discissions and 94 YAG laser discissions) were included in the statistical analysis.
Results The mean time from cataract surgery to surgical discission was 2.14 years «1 year in 14 eyes); the mean time from cataract surgery to YAG laser discission was 2.87 years «1 year in 12 eyes) (P <.05). Of the discissions, 53% (131) were performed in the second or third year after cataract surgery, but 9% (21) were performed after the third year. There was no trend toward an earlier discission (in terms of either vision or time after cataract surgery) over the years, even after the introduction of the YAG laser discission office procedure. The mean time from cataract surgery to discission was not statistically different in patients with diabetes, glaucoma, or intraocular lenses compared with the absence of these features (Table 2). The mean visual acuity before cataract surgery was 20/319 and before discission it was 20/172. The mean final visual acuity after discission was not statistically different between the
TABLE1 FREQUENCY OF DISCISSION AFTER CATARACT SURGERY
EYES NEEDING DISCISSION GROUP OF EYES
NO.
0/0
(YRS)
176
39
22.1
3.18
558 184 364 10
81 47 33 1
14.5 25.5 9.1
3.47 3.79 3.29
Extracapsular cataract extraction alone
MEAN FOLLOW-UP
NO.
Extracapsular cataract extraction plus
intraocular lens Transiridectomy clip Posterior chamber Other
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TABLE2
TABLE 3
SUMMARY OF CLINICAL DATA
CAUSES OF POOR VISION AFTER DISCISSION NO. OF EYES
DISCISSION YAG CLINICAL DATA
SURGICAL
LASER
TOTAL
No. of eyes
153
94
247
Females
104
63 31
167
Males
49
CONDITION'
Macular degeneration
80
Other macular disease
Right eye
81
41
122
Cystoid macular edema
Left eye
72
53
125
Corneal edema before
None
71
39
110
Corneal edema from
Transiridectomy clip
41 39
6 44
47
Posterior chamber
SURGICAL
YAG LASER
DISCISSION
DISCISSION
(NO.
~
153)
(NO.
8 2 4
~
95)
4 6 3
discission
Style of intraocular lens
83
vitreous touch
o
Recurrent postcataract
Medallion
2
1
3
membrane (no additional
Anterior chamber
0
3
3
surgery)
Binkhorst
0
1
1
Mean age at cataract surgery (yrs)
65.4
Mean age at discission (yrs)
67.6
64.8 67.7
1
o
o
Ischemic optic neuropathy
65.2
Amblyopia or nystagmus
3
1
67.7
Glaucoma
o
1 1
Interval between cataract surgery *Disease causing final visual acuities of 20/40 or worse.
and discission (yrs) Mean
2.14
2.87
Median
2.03
2.77
2.42 2.14
Eyes with no intraocular lens (110 eyes)
2.53
Eyes with posterior chamber lens (83 eyes)
2.13
Eyes with transiridectomy clip (47 eyes)
2.64
Mean visual acuity" Before cataract surgery
20/320
20/319
Before discission
20/166
20/184
20/172
After discission
20/33
20/44
20/37
20/319
"Snellen visual acuity was converted to log visual acuity, the mean determined, and then converted back to Snellen visual acuity.
two groups (Table 2). None of the 247 eyes had a decrease in central vision after the surgical or YAG laser discission. Table 3 lists the reasons for visual acuities of 20/40 or worse after discission. Conditions related to the discission included cystoid macular edema, corneal edema from vitreous touch, and recurrence of the postcataract membrane. We found no significant associations between the predominant type of cataract (posterior subcapsular, nuclear sclerotic, cortical, mature, congenital, or unknown) and the resulting type of capsular opacification (pearl formation, fibrosis, or thickened capsule with haze) (Table 4). There were fewer eyes with pearl
formation in the patients with posterior chamber lenses than in the patients without intraocular lenses (P <.OOl).or those with transiridectomy clip lenses (P <.02). The surgical discissions were done with the patient under retrobulbar anesthesia in 99 cases, topical anesthesia in 48 cases, and general anesthesia in six cases. The YAG laser discissions were done with the patient under topical anesthesia in 93 cases and retrobulbar anesthesia in one case. After surgical discission, the anterior hyaloid face was intact in 84 cases, broken in 41, and unknown in 28. In the YAG laser discission group, the anterior hyaloid face was intact in 44 cases, broken in 46, and unknown in four. Intraocular pressure-Of the 247 eyes, 27 had glaucoma before cataract surgery (13 in the surgical group and 14 in the YAG laser group) (Table 5). Of all the eyes that underwent cataract surgery at the Mayo Clinic, 30.1 % (64 eyes) had increased intraocular pressures (>22 mm Hg) during the first few days after surgery. These increased intraocular pressures were not related to the use of viscoelastic substances." In nine eyes, glaucoma treatment was discontinued after cataract surgery; glaucoma was newly diagnosed in only one patient after cataract surgery. Eighteen patients were taking medication for glaucoma at the time of their discissions (ten in the surgical group and
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TABLE 4 CAPSULAR OPACIFICATION IN 247 CATARACT PATIENTS UNDERGOING DISCISSION TYPE OF CAPSULAR OPACIFICATION (NO. OF EYES) CLINICAL DATA
NO.
PEARLS
FIBROSIS
HAZE
Unknown
35
26 17 0 6 2 7
12
Congenital
102 73 4 23 10
64 47 4 13 7 20
9 5 19 1
Type of cataract Posterior subcapsular Nuclear sclerotic Cortical Mature
9 0 4 1 8
Style of intraocular lens
110
37
Transiridectomy clip
47
12
Posterior chamber
83 3 3 1
8 0 1
None
Medallion Anterior chamber Binkhorst
0 0
0
eight in the YAG laser group). After the discissions, all 18 of these patients continued taking the same medications, without evident change in status. Three additional patients later started taking glaucoma medications, one in the surgical group and two in the YAG laser group.
64 30 56 2 2 1
The mean intraocular pressures before discission were not statistically different between the two groups. Six patients had intraocular pressures greater than 22 mm Hg immediately before discission. Two to five hours after YAG laser discission, the mean of the highest intra-
TABLE 5 INTRAOCULAR PRESSURE RESPONSE AFTER SURGICAL AND YAG LASER DISCISSIONS DISCISSION
MEASUREMENT
TOTAL
YAG LASER
SURGICAL NO. OF
lOP'
NO. OF
lOP'
NO. OF
lOP'
EYES
(MM HG)
EYES
(MM HG)
EYES
(MM HG)
153
15.2
94
14.9
247
15.1
2 141 18 86
94 11
33
35.5 16.5 22.0 15.8 16.2
88 79 67
23.2 18.4 15.4 15.5 16.2
96 152 106 165 100
23.4 16.6 16.5 15.7 16.2
13
18.6
14
13.5
27
16.0
14
19.1
13
20.4
7 3
18.4 15.3
14 13 11
16.4 14.1 16.3
20 14
15.6 16.1
Total group Before discission After discission At 2 to 5 hrs At 1 day At 1 wk At 1 mo At six mos Group with preoperative glaucoma Before discission After discission At 2 to 5 hrs At 1 day At 1 wk At 1 mo At 6 mos 'lOP, intraocular pressure.
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Vol. 100, No.4
~
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20 10
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5
10
15
25
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Prediscission intraocular pressure Two to five hours after the YAG laser discissions and one day after the surgical discissions, the intraocular pressures were higher in eyes without intraocular lenses than in those with either posterior chamber implants or other implants. The differences were not statistically significant. Whether the anterior hyaloid face was intact or broken did not significantly affect the intraocular pressure measured after two to five hours in the YAG laser group and after one day in the surgical group. The presence or absence of an abnormal intraocular pressure (>22 mm Hg) at some time during the 24-hour period after discission was correlated with an abnormal intraocular pressure before the discission, with a history of glaucoma at any time before the discission, and with the absence of an intraocular lens. The presence or absence of increased intraocular pressure, however, was not related to the style
ocular pressure was 23.2 mm Hg; 48 eyes (51.1 %) had intraocular pressures greater than 22 mm Hg and four (4.3%) had intraocular pressures greater than 40 mm Hg. The ranges of intraocular pressure in this group showed a wide and unpredictable variation both before and after YAG laser discission (Fig. 2). The intraocular pressures of 141 patients who had surgical discissions were checked one day after the procedure; 18 (12.8%) had intraocular pressures greater than 22 mm Hg and two (1.4%) had intraocular pressures greater than 40 mm Hg (Fig. 3). One month and six months after discission, the mean intraocular pressure was greater than that before the discission for both groups. The difference between the two groups was not statistically significant, but the increase was significant at six months in the YAG laser group (P = .005) but not in the surgical group. >.
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•
20 10
0
0
5
10
15
20
Prediscission intraocular pressure
25
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AMERICAN JOURNAL OF OPHTHALMOLOGY
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Fig. 4 (Liesegang, Bourne, and Ilstrup). The maximum intraocular pressure two to five hours after YAG laser discission in 94 patients compared with the maximum millijoules of energy used to perform the procedure .
3.0
Maximum millijoule utilized
of intraocular lens, the degree of visual reduction, the type of capsular opacity (haze, fibrosis, or pearls), or the occurrence of increased intraocular pressure with the initial cataract surgery. The mean of the total energy utilized in the total group (that is, millijoules multiplied by the number of bursts) was 64.5 m]. There was no relationship between the mean of the millijoules, the maximal millijoules, the number of bursts, or the mean of the total energy and whether or not intraocular pressure was abnormal two to five hours after discission (Figs. 4 and 5). Endothelial cell loss-Fourteen eyes in the surgical group and 48 eyes in the YAG laser group had central endothelial photographs immediately before the operation and one week
and six months postoperatively. The mean endothelial cell density before the discission was 2,316 cells/mm" in the surgical group and 2,284 cells/mm'' in the YAG laser group. There was no significant loss of endothelial cells with either of these procedures at one week or at six months, when there was a mean 2% cell gain (53 cells) in the surgical group and a 6% cell gain (146 cells) in the YAG laser group. Complications-Six patients in the surgical discission group had vitreous manipulation at the time of surgery (usually lysis of a single vitreous strand) and one patient had a vitreous wick truncated in the office (Table 6). The wound leaks were all transient. Iritis occurred in three patients but resolved within one month, as did a sterile hypopyon in one patient. One patient had a surgical discission one
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Fig. 5 (Liesegang, Bourne, and Ilstrup). The maximum intraocular pressure two to five hours after YAG laser discission in 94 patients compared with the total energy (millijoule multiplied by the number of shots) used to perform the procedure.
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TABLE 6 COMPLICATIONS OF DISCISSIONS IN CATARACT PATIENTS
COMPLICATIONS
SURGICAL DISCISSION (NO. = 161)
Vitreous surgery VVound leak Significant vitreous touch Corneal edema Sutures required Sterile hypopyon Persistent iritis Corneal abrasion Intraocular lens touch to cornea Closure of discission Unable to open capsule Retinal detachment Damage to intraocular lens Cystoid macular edema* Newly increased intraocular pressure
7 4 7 0 4 1 3 1 1 5 1 1 0 4 1
VAG LASER DISCISSION (NO. = 102)
o
o 1 1
o o 1
o o 2
o 1
20 5 2
*One patient in each group had cystoid macular edema before the discission.
year after a posterior chamber lens was implanted and had a retinal detachment three years after the discission. In the YAG laser discission group, the major complication was intraocular lens pitting; this was not visually important. The early intraocular pressures were not different in patients with pitted intraocular lenses. The patient with the retinal detachment had severe myopia and required a YAG laser discission one year after extracapsular cataract extraction; he suffered a retinal detachment four months after the discission although the anterior hyaloid face was intact. Two of the nine eyes with cystoid macular edema after surgical and YAG laser discissions had had edema before the discissions. The mean time of the discission after cataract surgery in these nine eyes was 2.2 years, with only one patient having the discission within one year of cataract surgery. Three of the nine eyes had intact anterior hyaloid faces.
Discussion The frequency of secondary discissions and the interval after primary cataract surgery are
517
highly variable, with children and younger adults being more likely to have opacifications.":" Seward and Doran" reported that 31J2 years after cataract surgery, the need for discission in adults declined, whereas Wilhelmus and Emery" noted that the incidence increased with time, reaching as high as 50% after three years. Our data for patients with a mean of more than three years of follow-up indicated that the discission rate with the posterior chamber lenses was lower than those without implants or with transiridectomy clip lenses. In our study 26 (10.5%) of the discissions were performed less than one year after cataract surgery and 21 (9%) were performed three or more years after cataract surgery. The attitudes of the patient and the surgeon can influence these data considerably. Of our patients, 45% had visual acuities worse than 20/400 at the time of cataract surgery and 9.3% had visual acuities worse than 20/400 at the time of discission. Wilhelmus and Emery'" demonstrated that polishing the posterior capsule does not decrease the frequency or delay the onset of opacification, and we doubt that experience is a factor in the subsequent avoidance of postcataract membranes. We have had a favorable discission rate with the posterior chamber lens and specifically with the angled posterior chamber intraocular lens with a posterior convex surface, but the follow-up period is still short. The kind of capsular opacification did not vary with the type of initial cataract, but the formation of pearls was significantly less behind the posterior chamber intraocular lens, possibly because of its adherence to the posterior capsule. Other studies have shown that age, sex, and type of cataract are not predictive of the need for discission. 15 The increase in intraocular pressure after YAG laser discission has been reported by others. 3,4,6-8,18-20 Some conditions are correlated with a greater likelihood of increased intraocular pressure immediately after YAG laser discission (for example, glaucoma and increased intraocular pressure before discission), but for most patients such increases cannot be predicted. We found no relationship between these increases and the thickness of the capsule, presence of Elschnig pearls, visual acuity, or type of opacification. The patients in this series were not treated in a random fashion and we realize a strict comparison of the surgical and YAG laser discission
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AMERICAN JOURNAL OF OPHTHALMOLOGY
groups is not completely valid. We do not have the data for the period two to five hours after surgical discissions as we do the data after YAG laser discissions, but the intraocular pressure increased significantly in a number of patients one day after surgical discission. In the YAG laser discission group, the increase in intraocular pressure was not related to the power selected, the number of bursts, or the total energy.3,7,21 We performed relatively small capsulotomies, so we were not able to correlate the presence of an increase in intraocular pressure with the size of the capsulotomy, as others have done." These data led us to suspect that some factor in the vitreous may permeate the anterior chamber at discission, causing a temporary change in the facility of outflow.P' Eyes with posterior chamber intraocular lenses have the lowest increases in intraocular pressure.F presumably because of a slower release of these factors as a result of the barrier function of the intraocular lens against the posterior capsule. We prefer this conclusion rather than shock to the trabecular meshwork, capsular debris," or rna terial leaching from the intraocular lens. 24,25 The lack of correlation with the type of capsule, the amount of energy, and the occurrence of increased intraocular pressure with surgical discission support this concept. Intraocular lenses with ultraviolet-impeding properties were not used in this series of patients. The increase in intraocular pressure is transient in most patients, but it can lead to progressive visual field loss" or blindness." We continue to perform YAG laser discission in the morning so that the patient can be examined frequently throughout the day. Although frequently regarded as an office procedure, surgical discission has potential complications. The frequency of vitreous manipulation, vitreous wick, wound leak, the need for sutures, intraocular lens touch, and severe intraocular inflammation was high in the surgical group despite an attempt to provide ideal control in the operating room. These surgical complications were proportional to the experience of the surgeon. The YAG laser discission group had fewer complications. The pitting damage to the intraocular lenses did not influence vision. The incidence of pitting has been reported to vary from 10% to 33%.6,27 Later complications seen in both YAG laser and surgical discission groups included vitreous touch to the cornea, cystoid macular edema, retinal detachment, and persistent increased intraocular pressure. In a
October, 1985
larger series of patients undergoing YAG laser discission, cystoid macular edema occurred in 2.3% (persistent in 0.2%), glaucoma in 3.6% (persistent in 0.8%), and retinal detachment in 0.4% (persistent in 0.2%).21 In surgical discission, the reported incidences of retinal detachment range from less than 0.1 % to 2.4%2,28 and those of cystoid macular edema from 3.5% to 9.5% .28,29 Keates and associates" reported that cystoid macular edema is less after YAG laser discission than after surgical discission. Delaying the discission for several years after the primary catatract surgery may not help prevent retinal detachment or cystoid macular edema. In another study" the anterior hyaloid face was intact in 78% of patients after a secondary surgical discission. The frequency of disruption of the anterior hyaloid face, especially with YAG laser discission, is of concern because of its potential influence on retinal physiology and increased potential for later retinal detachment. 30,31 More recent studies have focused on vitreous changes (liquefaction) with YAG laser discission and suggest that the loss of the anterior hyaloid face and the molecular alterations within the vitreous gel are not innocuous and may take years before they produce manifest retinal changes." A mean loss of endothelial cells did not occur in our series, confirming previous results in animals 32.34 and humans.v" In an experimental rabbit model that used a mode-locked delivery system, however, Khodadoust and associates" found that corneal damage resulted when the YAG laser was focused as far away as 3.5 mm from the endothelium. Late closure of the capsulotomy has been noted after surgicalv" and YAG laser" discission and was fairly frequent in our series. This complication occurred three months to ten years after the original discission, and always in patients who had intact anterior hyaloid faces after the initial discission; there were no signs of inflammation or other evident reasons for the late closure.
References 1. The Miami Study Group: Cystoid macular edema in aphakic and pseudophakic eyes. Am. J. Ophthalmol. 88:45, 1979. 2. Percival, S. P. B., Anand, V., and Das, S. K.: Prevalence of aphakic retinal detachment. Br. J. Ophthalmol. 67:43, 1983. 3. Gardner, K. M., Straatsma, B. R., and Pettit,
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T. H.: Neodymium:YAG posterior capsulotomy. The first 100 cases at UCLA. Ophthalmic Surg. 16:24, 1985. 4. Terry, A. c., Stark, W. J., Maumenee, A. E., and Fagadau, W.: Neodymium-YAG laser for posterior capsulotomy. Am. J. Ophthalmol. 96:716, 1983. 5. Steinert, R. F., and Puliafito, C. A.: The Nd-YAG Laser in Ophthalmology. Principles and Clinical Applications of Photodisruption. Philadelphia, W. B. Saunders, 1985, pp. 72-95. 6. Stark, W. J., Worthen, D., Holladay, J. T., and Murray, G.: Neodymium:YAG lasers. An FDA report. Ophthalmology 92:209, 1985. 7. Flohr, M. J., Robin, A.L., and Kelley, J. S.: Early complications following Q-switched neodymium-YAG laser posterior capsulotomy. Ophthalmology 92:360, 1985. 8. Kraff, M. C.; Sanders, D. R., and Lieberman, H. 1.: Intraocular pressure and the corneal endothelium after neodymium:YAG laser posterior capsulotomy. Arch. Ophthalmol. 103:511, 1985. 9. Boniuk, M.: Comments about the posterior capsule. In Emery, J. M., and Jacobson, A. C. (eds.): Current Concepts in Cataract Surgery. Selected Proceedings of the Sixth Biennial Cataract Surgical Congress. St. Louis, C. V. Mosby, 1980, pp. 297 and 298. 10. Callahan, M. A.: Complications after capsulotomy following Kelman phacoemulsification. In Emery, J. M., and Jacobson, A. C. (eds.): Current Concepts in Cataract Surgery. Selected Proceedings of the Sixth Biennial Cataract Surgical Congress. St. Louis, C. V. Mosby, 1980, pp. 298-304. 11. Ad Hoc Committee on Ophthalmic Procedures Assessment: Academy recommendation. Ophthalmology 91:539, 1984. 12. Bourne, W. M., Liesegang, T. J., Waller, R. R., and Ilstrup, D. M.: The effect of sodium hyaluronate on endothelial cell damage during extracapsular cataract extraction and posterior lens implantation. Am. J. Ophthalmol. 98:759, 1984. 13. Seward, H. c.. and Doran, R. M. 1.: Posterior capsulotomy and retinal detachment following extracapsular lens surgery. Br. J. Ophthalmol. 68:379, 1984. 14. Pearce, J. 1.: Modern simple extracapsular surgery. Trans. Ophthalmol. Soc. U.K. 99:176, 1979. 15. Wilhelmus, K. R., and Emery, J. M.: Posterior capsule opacification following phacoemulsification. Ophthalmic Surg. 11:264, 1980. 16. Park, D. W., II, and Emery, J. M.: Cystoid macular edema after discission. Primary vs. secondary. In Emery, J. M., and Jacobson, A. C. (eds.): Current Concepts in Cataract Surgery. Selected Proceedings of the Seventh Biennial Cataract Surgical Congress. Norwalk, Appleton-Century-Crofts, 1982, pp. 237-241. 17. Wilhelmus, K. R., and Emery, J. M.: Posterior capsular opacification following phacoemulsification. In Emery, J. M., and Jacobson, A. C. (eds.): Current Concepts in Cataract Surgery. Selected Proceedings of the Sixth Biennial Cataract Surgical Congress. St. Louis, C. V. Mosby, 1980, pp. 304-308.
519
18. Channell, M. M., and Beckman, H.: Intraocular pressure changes after neodymium:YAG laser posterior capsulotomy. Arch. Ophthalmol. 102:1024, 1984. 19. Parker, W. T., Clorfeine, G. S., and Stocklin, R. D.: Marked intraocular pressure rise following Nd:YAG laser capsulotomy. Ophthalmic Surg. 15:103, 1984. 20. Richter, C. U., Arzeno, F., Pappas, H. R., Steinert, R. F., Puliafito, C.; and Epstein, D. 1.: Intraocular pressure elevation following Nd:YAG laser posterior capsulotomy. Ophthalmology 92:636, 1985. 21. Keates, R. H., Steinert, R. F., Puliafito, C. A., and Maxwell, S. K.: Long-term followup of Nd:YAG laser posterior capsulotomy. J. Am. Intraocul. Implant Soc. 10:164, 1984. 22. Hoffer, K. J.: YAG and lOP. Ophthalmic Surg. 15:610, 1984. 23. Khodadoust, A. A., Arkfeld, D. F., Caprioli, J., and Sears, M. 1.: Ocular effect of neodymiumYAG laser. Am. J. Ophthalmol. 98:144, 1984. 24. Lerman, S., Thrasher, B., and Moran, M.: Vitreous changes after neodymium-VAG laser irradiation of the posterior lens capsule or mid-vitreous. Am. J. Ophthalmol. 97:470, 1984. 25. Terry, A. c., Stark, W. J., Newsome, D. A., Maumenee, A. E., and Pine, E.: Tissue toxicity of laser-damaged intraocular lens implants. Ophthalmology 92:414, 1985. 26. Kurata, F., Krupin, T., Sinclair, S., and Karp, 1.: Progressive glaucomatous visual field loss after neodymium-VAG laser capsulotomy. Am. J. Ophthalmol. 98:632, 1984. 27. Blackwell, c.. Hirst, 1. W., and Kinnas, S. J.: Neodymium-YAG capsulotomy and potential blindness. Am. J. Ophthalmol. 98:521, 1984. 28. Lindstrom, R. 1., and Harris, W. S.: Management of the posterior capsule following posterior chamber lens implantation. J. Am. Intraocul. Implant Soc. 6:255, 1980. 29. Livernois, R., and Sinskey, R. M.: Complications of later capsulotomy. J. Am. Intraocul. Implant Soc. 7:242, 1981. 30. Fastenberg, D. M., Schwartz, P. 1., and Lin, H. Z.: Retinal detachment following neodymiumYAG laser capsulotomy. Am. J. Ophthalmol. 97:288, 1984. 31. McPherson, A. R., O'Malley, R. E., and Bravo, J.: Retinal detachment following later posterior capsulotomy. Am. J. Ophthalmol. 95:593, 1983. 32. Meyer, K. T., Pettit, T. H., and Straatsma, B. R.: Corneal endothelial damage with neodymium:YAG laser. Ophthalmology 91:1022, 1984. 33. Peyman, G. A., Kraff, M., and Viherkoski, E.: Noninvasive capsulectomy using a new pulsed infrared laser. J. Am. Intraocul. Implant Soc. 8:239, 1982. 34. Puliafito, C. A., and Steinert, R. F.: Experimental lens laser surgery. In Trokel, S. 1. (ed.): YAG Laser Ophthalmic Microsurgery. Norwalk, Appleton-Century-Crofts, 1983, pp. 93-100.
J. Liesegang,
M.D., William M. Bourne, M.D., and Duane M. Ilstrup, M.S.
Between November 1978 and June 1984, 161 surgical and 102 neodymium-YAG laser discissions were performed. The incidence of discission in patients with a mean three-year followup after extracapsular surgery was 22.1 % (39 of 176 eyes) after extracapsular cataract extraction alone and 14.5% (81 of 558 eyes) after extracapsular cataract extraction with intraocular lens implantation (P <.02); the incidence was 25.5% (47 of 184 eyes) with the transiridectomy clip lens and 9.1% (33 of 364 eyes) with the posterior chamber lens (P <.001). The average interval between cataract surgery and the discission was 2.4 years. The intraocular pressure was increased in 51 % (48 eyes) of the eyes two to five hours after YAG laser discission and was unpredictable in most patients. After surgical discission, the intraocular pressure was increased on the first postoperative day in 13% (18 eyes) of the eyes. With surgical discission, significant complications included vitreous manipulation, wound leak, and intraocular inflammation. Intraocular lens pitting occurred in 20 patients undergoing YAG laser discission. Complications with both procedures included cystoid macular edema, retinal detachment, glaucoma, and closure of a previously adequate discission opening. THE POPULARITY of extracapsular cataract extraction has increased because of the advantages of the posterior capsule in stabilizing the Accepted for publication July 15, 1985. From the Departments of Ophthalmology (Drs. Liesegang and Bourne) and Medical Statistics and Epidemiology (Mr. Ilstrup), Mayo Clinic and Mayo Foundation, Rochester, Minnesota. This study was supported in part by research grant EY-02037 from the National Institutes of Health, by Research to Prevent Blindness, Inc., and by the Mayo Foundation. Reprint requests to Thomas J. Liesegang, M.D., Department of Ophthalmology, Mayo Clinic, Rochester, MN 55905.
510
intraocular lens implant as well as anterior and posterior segment structures. This procedure may also be associated with a lower incidence of cystoid macular edema! and aphakic retinal detachment," The main disadvantage is the high incidence of opacification of the posterior capsule. Previous treatments for a cloudy posterior capsule included polishing the capsule and surgical discission. The neodymium-YAG laser recently became available in the United States as an alternative means of rupturing the posterior capsule. We studied the Mayo Clinic experience with a consecutive series of surgical discissions and then a consecutive series of YAG laser discissions. A number of reports on YAG laser discissions have appeared.r" but there are few comparative reports on the complications of surgical discissions."" The ocular risks from the YAG laser are related to the transmitted shock, electromagnetic energy, and perhaps other effects that are presently unknown." Long-term follow-up will be necessary to evaluate the safety of this technique fully.
Subjects and Methods All cases of extracapsular cataract surgery with or without an intraocular lens implant and all secondary surgical or YAG laser discissions performed at the Mayo Clinic between Nov. 1, 1978, and June 15, 1984, were tabulated. The extracapsular extraction consisted of manual expression of the nucleus, aspiration of the cortex with a Kelman irrigation and aspiration unit, and scratching of the posterior capsule as necessary. The intraocular lenses were originally inserted under air, but since 1983 they have been inserted under sodium hyaluronate, which is removed at the completion of the procedure. Surgical discissions were all performed in the operating room under sterile conditions. The globe was fixed, a Swan knife
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Surgical and Laser Discissions
passed through the corneosclerallimbus, and a vertical discission made. In November 1983, the YAG laser began to be used. Before the YAG laser discission was performed, the patient was given topical anesthesia and the pupil dilated; usually an Abraham contact lens was utilized. The least power in millijoules (one pulse per burst) capable of achieving a discission was selected and focused on the posterior capsule to accomplish a small capsulotomy. Patients were examined two and five hours after the procedure, during which time medications were not routinely administered. All patients were examined before and after cataract surgery and discission until either December 1984 or the last follow-up visit. All patients who had undergone YAG laser discission were examined in a prospective study. Endothelial cell photographs were taken with a specular microscope preoperatively and one week and six months after discission. Many of the patients with surgical discissions were being monitored as part of a continuing study on the efficacy and safety of intraocular lenses and had endothelial cell photographs taken either at regular intervals or in association with the surgical discission. We excluded from some of the statistical comparisons patients who had two discissions in the same eye but included patients who had undergone discission on both eyes by different
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300
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techniques and patients who had undergone discission on both eyes by the same technique (although only one eye was selected at random). In tabulating the complications, however, we considered all discissions. We used the Wilcoxon rank-sum test, two-sample t-test, X2 test, and signed-rank test for statistical analysis with P <.05 considered to be significant. Between Nov. I, 1978, and June 15, 1984, a total of 3,207 extracapsular cataract extractions were performed at the Mayo Clinic. Of these 3,207 operations, 645 were extracapsular cataract extractions alone and 2,562 were extracapsular cataract extractions with placement of an intraocular lens (Fig. 1). During this same time, 263 secondary discissions were performed in 257 eyes of 239 patients. The first 161 discissions were surgical, and the last 102 discissions were performed with the neodymium-YAG laser. We have not performed a secondary surgical discission since obtaining the YAG laser in November 1983. Nineteen of the discissions were performed on eyes that had undergone cataract surgery at the Mayo Clinic before November 1978, and 35 discissions (16 surgical and 19 YAG laser) were performed on 35 eyes of patients who did not have their primary cataract surgery at the Mayo Clinic. Twelve patients had surgical discission on both eyes; two patients had YAG laser discissions in both eyes; four patients had surgical discissions in one eye and YAG laser discissions in the other eye;
200 150
.a 100 E ::J 50 Z 0
1978 .ECCE • ECCE and IOL
5
(645) (2562)
15
~Surgical discission (161) (102) OYAG discission
0 0
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J-J J-D 1983
J-J 1984
37 97 79 85 52 62 63 52 38 33 42 80 137 141 162 207 197 241 262 296 402 422 1 0
1 0
8 0
12 0
16 0
18 0
30 0
32 0
23 0
20 27
0 75
Fig. 1 (Liesegang, Bourne, and Ilstrup). The number of extracapsular cataract extractions (ECCE), extracapsular cataract extractions with intraocular lens implants (ECCE and 10L), surgical discissions, and YAG laser discissions performed at the Mayo Clinic between Nov. I, 1978, and June 15, 1984.
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five patients with surgical discissions later underwent closure of the discission opening. Of these, four had YAG laser discissions. Two patients with YAG laser discissions later had additional YAG laser applications to open the discission further. Transiridectomy clip implants were used between February 1979 and April 1982. We began using posterior chamber implants in April 1979 and posterior chamber implants with convex posterior surfaces in February 1982. Ultraviolet-absorbing lenses were not used. Of the 645 eyes with planned extracapsular cataract extractions performed at the Mayo Clinic, 100 had required discissions as of June 1984; of the 2,562 eyes with planned extracapsular cataract extractions and placement of intraocular lenses, 113 had required discissions as of June 1984. Of the 2,370 eyes with posterior chamber intraocular lenses, 71 required discissions. Of these posterior chamber lenses, 718 had convex posterior surfaces. Four of these eyes required discissions. Of the 192 eyes with transiridectomy clip implants after extracapsular cataract extraction, 42 required discissions. Some of these patients may subsequently have had discissions elsewhere without our knowledge. Because the follow-up periods varied greatly among these different styles of implants, we did not believe that a statistical comparison of the incidence of discission in these groups would be valid. In our ongoing intraocular lens study (entry into this study was terminated in 1982), however, the follow-up is closely monitored and is now more than three years for most patients, including 558 patients with extracapsular cataract extractions and intraocular lens implantation and 176 patients with extracapsular cata-
ract extractions alone (the control group). There was a significantly higher rate of discission in patients with extracapsular cataract extractions (39 of 76 eyes or 22.1 %) than in those with extracapsular cataract extractions and intraocular lens implants (81 of 558 eyes or 14.5%) (P <.02). Patients with posterior chamber implants had a lower rate of discission (33 of 364 eyes or 9.1%) than did patients with transiridectomy clip implants (47 of 184 eyes or 25.5%) (P <.001; Table 1). A total of 247 eyes (153 surgical discissions and 94 YAG laser discissions) were included in the statistical analysis.
Results The mean time from cataract surgery to surgical discission was 2.14 years «1 year in 14 eyes); the mean time from cataract surgery to YAG laser discission was 2.87 years «1 year in 12 eyes) (P <.05). Of the discissions, 53% (131) were performed in the second or third year after cataract surgery, but 9% (21) were performed after the third year. There was no trend toward an earlier discission (in terms of either vision or time after cataract surgery) over the years, even after the introduction of the YAG laser discission office procedure. The mean time from cataract surgery to discission was not statistically different in patients with diabetes, glaucoma, or intraocular lenses compared with the absence of these features (Table 2). The mean visual acuity before cataract surgery was 20/319 and before discission it was 20/172. The mean final visual acuity after discission was not statistically different between the
TABLE1 FREQUENCY OF DISCISSION AFTER CATARACT SURGERY
EYES NEEDING DISCISSION GROUP OF EYES
NO.
0/0
(YRS)
176
39
22.1
3.18
558 184 364 10
81 47 33 1
14.5 25.5 9.1
3.47 3.79 3.29
Extracapsular cataract extraction alone
MEAN FOLLOW-UP
NO.
Extracapsular cataract extraction plus
intraocular lens Transiridectomy clip Posterior chamber Other
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513
TABLE2
TABLE 3
SUMMARY OF CLINICAL DATA
CAUSES OF POOR VISION AFTER DISCISSION NO. OF EYES
DISCISSION YAG CLINICAL DATA
SURGICAL
LASER
TOTAL
No. of eyes
153
94
247
Females
104
63 31
167
Males
49
CONDITION'
Macular degeneration
80
Other macular disease
Right eye
81
41
122
Cystoid macular edema
Left eye
72
53
125
Corneal edema before
None
71
39
110
Corneal edema from
Transiridectomy clip
41 39
6 44
47
Posterior chamber
SURGICAL
YAG LASER
DISCISSION
DISCISSION
(NO.
~
153)
(NO.
8 2 4
~
95)
4 6 3
discission
Style of intraocular lens
83
vitreous touch
o
Recurrent postcataract
Medallion
2
1
3
membrane (no additional
Anterior chamber
0
3
3
surgery)
Binkhorst
0
1
1
Mean age at cataract surgery (yrs)
65.4
Mean age at discission (yrs)
67.6
64.8 67.7
1
o
o
Ischemic optic neuropathy
65.2
Amblyopia or nystagmus
3
1
67.7
Glaucoma
o
1 1
Interval between cataract surgery *Disease causing final visual acuities of 20/40 or worse.
and discission (yrs) Mean
2.14
2.87
Median
2.03
2.77
2.42 2.14
Eyes with no intraocular lens (110 eyes)
2.53
Eyes with posterior chamber lens (83 eyes)
2.13
Eyes with transiridectomy clip (47 eyes)
2.64
Mean visual acuity" Before cataract surgery
20/320
20/319
Before discission
20/166
20/184
20/172
After discission
20/33
20/44
20/37
20/319
"Snellen visual acuity was converted to log visual acuity, the mean determined, and then converted back to Snellen visual acuity.
two groups (Table 2). None of the 247 eyes had a decrease in central vision after the surgical or YAG laser discission. Table 3 lists the reasons for visual acuities of 20/40 or worse after discission. Conditions related to the discission included cystoid macular edema, corneal edema from vitreous touch, and recurrence of the postcataract membrane. We found no significant associations between the predominant type of cataract (posterior subcapsular, nuclear sclerotic, cortical, mature, congenital, or unknown) and the resulting type of capsular opacification (pearl formation, fibrosis, or thickened capsule with haze) (Table 4). There were fewer eyes with pearl
formation in the patients with posterior chamber lenses than in the patients without intraocular lenses (P <.OOl).or those with transiridectomy clip lenses (P <.02). The surgical discissions were done with the patient under retrobulbar anesthesia in 99 cases, topical anesthesia in 48 cases, and general anesthesia in six cases. The YAG laser discissions were done with the patient under topical anesthesia in 93 cases and retrobulbar anesthesia in one case. After surgical discission, the anterior hyaloid face was intact in 84 cases, broken in 41, and unknown in 28. In the YAG laser discission group, the anterior hyaloid face was intact in 44 cases, broken in 46, and unknown in four. Intraocular pressure-Of the 247 eyes, 27 had glaucoma before cataract surgery (13 in the surgical group and 14 in the YAG laser group) (Table 5). Of all the eyes that underwent cataract surgery at the Mayo Clinic, 30.1 % (64 eyes) had increased intraocular pressures (>22 mm Hg) during the first few days after surgery. These increased intraocular pressures were not related to the use of viscoelastic substances." In nine eyes, glaucoma treatment was discontinued after cataract surgery; glaucoma was newly diagnosed in only one patient after cataract surgery. Eighteen patients were taking medication for glaucoma at the time of their discissions (ten in the surgical group and
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TABLE 4 CAPSULAR OPACIFICATION IN 247 CATARACT PATIENTS UNDERGOING DISCISSION TYPE OF CAPSULAR OPACIFICATION (NO. OF EYES) CLINICAL DATA
NO.
PEARLS
FIBROSIS
HAZE
Unknown
35
26 17 0 6 2 7
12
Congenital
102 73 4 23 10
64 47 4 13 7 20
9 5 19 1
Type of cataract Posterior subcapsular Nuclear sclerotic Cortical Mature
9 0 4 1 8
Style of intraocular lens
110
37
Transiridectomy clip
47
12
Posterior chamber
83 3 3 1
8 0 1
None
Medallion Anterior chamber Binkhorst
0 0
0
eight in the YAG laser group). After the discissions, all 18 of these patients continued taking the same medications, without evident change in status. Three additional patients later started taking glaucoma medications, one in the surgical group and two in the YAG laser group.
64 30 56 2 2 1
The mean intraocular pressures before discission were not statistically different between the two groups. Six patients had intraocular pressures greater than 22 mm Hg immediately before discission. Two to five hours after YAG laser discission, the mean of the highest intra-
TABLE 5 INTRAOCULAR PRESSURE RESPONSE AFTER SURGICAL AND YAG LASER DISCISSIONS DISCISSION
MEASUREMENT
TOTAL
YAG LASER
SURGICAL NO. OF
lOP'
NO. OF
lOP'
NO. OF
lOP'
EYES
(MM HG)
EYES
(MM HG)
EYES
(MM HG)
153
15.2
94
14.9
247
15.1
2 141 18 86
94 11
33
35.5 16.5 22.0 15.8 16.2
88 79 67
23.2 18.4 15.4 15.5 16.2
96 152 106 165 100
23.4 16.6 16.5 15.7 16.2
13
18.6
14
13.5
27
16.0
14
19.1
13
20.4
7 3
18.4 15.3
14 13 11
16.4 14.1 16.3
20 14
15.6 16.1
Total group Before discission After discission At 2 to 5 hrs At 1 day At 1 wk At 1 mo At six mos Group with preoperative glaucoma Before discission After discission At 2 to 5 hrs At 1 day At 1 wk At 1 mo At 6 mos 'lOP, intraocular pressure.
Surgical and Laser Discissions
Vol. 100, No.4
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•
20 10
o • o
5
10
15
25
20
Prediscission intraocular pressure Two to five hours after the YAG laser discissions and one day after the surgical discissions, the intraocular pressures were higher in eyes without intraocular lenses than in those with either posterior chamber implants or other implants. The differences were not statistically significant. Whether the anterior hyaloid face was intact or broken did not significantly affect the intraocular pressure measured after two to five hours in the YAG laser group and after one day in the surgical group. The presence or absence of an abnormal intraocular pressure (>22 mm Hg) at some time during the 24-hour period after discission was correlated with an abnormal intraocular pressure before the discission, with a history of glaucoma at any time before the discission, and with the absence of an intraocular lens. The presence or absence of increased intraocular pressure, however, was not related to the style
ocular pressure was 23.2 mm Hg; 48 eyes (51.1 %) had intraocular pressures greater than 22 mm Hg and four (4.3%) had intraocular pressures greater than 40 mm Hg. The ranges of intraocular pressure in this group showed a wide and unpredictable variation both before and after YAG laser discission (Fig. 2). The intraocular pressures of 141 patients who had surgical discissions were checked one day after the procedure; 18 (12.8%) had intraocular pressures greater than 22 mm Hg and two (1.4%) had intraocular pressures greater than 40 mm Hg (Fig. 3). One month and six months after discission, the mean intraocular pressure was greater than that before the discission for both groups. The difference between the two groups was not statistically significant, but the increase was significant at six months in the YAG laser group (P = .005) but not in the surgical group. >.
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Fig. 3 (Liesegang, Bourne, and Ilstrup). Intraocular pressure before discission compared with the intraocular pressure one day after surgical discission in 141 patients. Line indicates no change.
•
20 10
0
0
5
10
15
20
Prediscission intraocular pressure
25
516
AMERICAN JOURNAL OF OPHTHALMOLOGY
October, 1985
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Fig. 4 (Liesegang, Bourne, and Ilstrup). The maximum intraocular pressure two to five hours after YAG laser discission in 94 patients compared with the maximum millijoules of energy used to perform the procedure .
3.0
Maximum millijoule utilized
of intraocular lens, the degree of visual reduction, the type of capsular opacity (haze, fibrosis, or pearls), or the occurrence of increased intraocular pressure with the initial cataract surgery. The mean of the total energy utilized in the total group (that is, millijoules multiplied by the number of bursts) was 64.5 m]. There was no relationship between the mean of the millijoules, the maximal millijoules, the number of bursts, or the mean of the total energy and whether or not intraocular pressure was abnormal two to five hours after discission (Figs. 4 and 5). Endothelial cell loss-Fourteen eyes in the surgical group and 48 eyes in the YAG laser group had central endothelial photographs immediately before the operation and one week
and six months postoperatively. The mean endothelial cell density before the discission was 2,316 cells/mm" in the surgical group and 2,284 cells/mm'' in the YAG laser group. There was no significant loss of endothelial cells with either of these procedures at one week or at six months, when there was a mean 2% cell gain (53 cells) in the surgical group and a 6% cell gain (146 cells) in the YAG laser group. Complications-Six patients in the surgical discission group had vitreous manipulation at the time of surgery (usually lysis of a single vitreous strand) and one patient had a vitreous wick truncated in the office (Table 6). The wound leaks were all transient. Iritis occurred in three patients but resolved within one month, as did a sterile hypopyon in one patient. One patient had a surgical discission one
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Fig. 5 (Liesegang, Bourne, and Ilstrup). The maximum intraocular pressure two to five hours after YAG laser discission in 94 patients compared with the total energy (millijoule multiplied by the number of shots) used to perform the procedure.
Vol. 100, No.4
Surgical and Laser Discissions
TABLE 6 COMPLICATIONS OF DISCISSIONS IN CATARACT PATIENTS
COMPLICATIONS
SURGICAL DISCISSION (NO. = 161)
Vitreous surgery VVound leak Significant vitreous touch Corneal edema Sutures required Sterile hypopyon Persistent iritis Corneal abrasion Intraocular lens touch to cornea Closure of discission Unable to open capsule Retinal detachment Damage to intraocular lens Cystoid macular edema* Newly increased intraocular pressure
7 4 7 0 4 1 3 1 1 5 1 1 0 4 1
VAG LASER DISCISSION (NO. = 102)
o
o 1 1
o o 1
o o 2
o 1
20 5 2
*One patient in each group had cystoid macular edema before the discission.
year after a posterior chamber lens was implanted and had a retinal detachment three years after the discission. In the YAG laser discission group, the major complication was intraocular lens pitting; this was not visually important. The early intraocular pressures were not different in patients with pitted intraocular lenses. The patient with the retinal detachment had severe myopia and required a YAG laser discission one year after extracapsular cataract extraction; he suffered a retinal detachment four months after the discission although the anterior hyaloid face was intact. Two of the nine eyes with cystoid macular edema after surgical and YAG laser discissions had had edema before the discissions. The mean time of the discission after cataract surgery in these nine eyes was 2.2 years, with only one patient having the discission within one year of cataract surgery. Three of the nine eyes had intact anterior hyaloid faces.
Discussion The frequency of secondary discissions and the interval after primary cataract surgery are
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highly variable, with children and younger adults being more likely to have opacifications.":" Seward and Doran" reported that 31J2 years after cataract surgery, the need for discission in adults declined, whereas Wilhelmus and Emery" noted that the incidence increased with time, reaching as high as 50% after three years. Our data for patients with a mean of more than three years of follow-up indicated that the discission rate with the posterior chamber lenses was lower than those without implants or with transiridectomy clip lenses. In our study 26 (10.5%) of the discissions were performed less than one year after cataract surgery and 21 (9%) were performed three or more years after cataract surgery. The attitudes of the patient and the surgeon can influence these data considerably. Of our patients, 45% had visual acuities worse than 20/400 at the time of cataract surgery and 9.3% had visual acuities worse than 20/400 at the time of discission. Wilhelmus and Emery'" demonstrated that polishing the posterior capsule does not decrease the frequency or delay the onset of opacification, and we doubt that experience is a factor in the subsequent avoidance of postcataract membranes. We have had a favorable discission rate with the posterior chamber lens and specifically with the angled posterior chamber intraocular lens with a posterior convex surface, but the follow-up period is still short. The kind of capsular opacification did not vary with the type of initial cataract, but the formation of pearls was significantly less behind the posterior chamber intraocular lens, possibly because of its adherence to the posterior capsule. Other studies have shown that age, sex, and type of cataract are not predictive of the need for discission. 15 The increase in intraocular pressure after YAG laser discission has been reported by others. 3,4,6-8,18-20 Some conditions are correlated with a greater likelihood of increased intraocular pressure immediately after YAG laser discission (for example, glaucoma and increased intraocular pressure before discission), but for most patients such increases cannot be predicted. We found no relationship between these increases and the thickness of the capsule, presence of Elschnig pearls, visual acuity, or type of opacification. The patients in this series were not treated in a random fashion and we realize a strict comparison of the surgical and YAG laser discission
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groups is not completely valid. We do not have the data for the period two to five hours after surgical discissions as we do the data after YAG laser discissions, but the intraocular pressure increased significantly in a number of patients one day after surgical discission. In the YAG laser discission group, the increase in intraocular pressure was not related to the power selected, the number of bursts, or the total energy.3,7,21 We performed relatively small capsulotomies, so we were not able to correlate the presence of an increase in intraocular pressure with the size of the capsulotomy, as others have done." These data led us to suspect that some factor in the vitreous may permeate the anterior chamber at discission, causing a temporary change in the facility of outflow.P' Eyes with posterior chamber intraocular lenses have the lowest increases in intraocular pressure.F presumably because of a slower release of these factors as a result of the barrier function of the intraocular lens against the posterior capsule. We prefer this conclusion rather than shock to the trabecular meshwork, capsular debris," or rna terial leaching from the intraocular lens. 24,25 The lack of correlation with the type of capsule, the amount of energy, and the occurrence of increased intraocular pressure with surgical discission support this concept. Intraocular lenses with ultraviolet-impeding properties were not used in this series of patients. The increase in intraocular pressure is transient in most patients, but it can lead to progressive visual field loss" or blindness." We continue to perform YAG laser discission in the morning so that the patient can be examined frequently throughout the day. Although frequently regarded as an office procedure, surgical discission has potential complications. The frequency of vitreous manipulation, vitreous wick, wound leak, the need for sutures, intraocular lens touch, and severe intraocular inflammation was high in the surgical group despite an attempt to provide ideal control in the operating room. These surgical complications were proportional to the experience of the surgeon. The YAG laser discission group had fewer complications. The pitting damage to the intraocular lenses did not influence vision. The incidence of pitting has been reported to vary from 10% to 33%.6,27 Later complications seen in both YAG laser and surgical discission groups included vitreous touch to the cornea, cystoid macular edema, retinal detachment, and persistent increased intraocular pressure. In a
October, 1985
larger series of patients undergoing YAG laser discission, cystoid macular edema occurred in 2.3% (persistent in 0.2%), glaucoma in 3.6% (persistent in 0.8%), and retinal detachment in 0.4% (persistent in 0.2%).21 In surgical discission, the reported incidences of retinal detachment range from less than 0.1 % to 2.4%2,28 and those of cystoid macular edema from 3.5% to 9.5% .28,29 Keates and associates" reported that cystoid macular edema is less after YAG laser discission than after surgical discission. Delaying the discission for several years after the primary catatract surgery may not help prevent retinal detachment or cystoid macular edema. In another study" the anterior hyaloid face was intact in 78% of patients after a secondary surgical discission. The frequency of disruption of the anterior hyaloid face, especially with YAG laser discission, is of concern because of its potential influence on retinal physiology and increased potential for later retinal detachment. 30,31 More recent studies have focused on vitreous changes (liquefaction) with YAG laser discission and suggest that the loss of the anterior hyaloid face and the molecular alterations within the vitreous gel are not innocuous and may take years before they produce manifest retinal changes." A mean loss of endothelial cells did not occur in our series, confirming previous results in animals 32.34 and humans.v" In an experimental rabbit model that used a mode-locked delivery system, however, Khodadoust and associates" found that corneal damage resulted when the YAG laser was focused as far away as 3.5 mm from the endothelium. Late closure of the capsulotomy has been noted after surgicalv" and YAG laser" discission and was fairly frequent in our series. This complication occurred three months to ten years after the original discission, and always in patients who had intact anterior hyaloid faces after the initial discission; there were no signs of inflammation or other evident reasons for the late closure.
References 1. The Miami Study Group: Cystoid macular edema in aphakic and pseudophakic eyes. Am. J. Ophthalmol. 88:45, 1979. 2. Percival, S. P. B., Anand, V., and Das, S. K.: Prevalence of aphakic retinal detachment. Br. J. Ophthalmol. 67:43, 1983. 3. Gardner, K. M., Straatsma, B. R., and Pettit,
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T. H.: Neodymium:YAG posterior capsulotomy. The first 100 cases at UCLA. Ophthalmic Surg. 16:24, 1985. 4. Terry, A. c., Stark, W. J., Maumenee, A. E., and Fagadau, W.: Neodymium-YAG laser for posterior capsulotomy. Am. J. Ophthalmol. 96:716, 1983. 5. Steinert, R. F., and Puliafito, C. A.: The Nd-YAG Laser in Ophthalmology. Principles and Clinical Applications of Photodisruption. Philadelphia, W. B. Saunders, 1985, pp. 72-95. 6. Stark, W. J., Worthen, D., Holladay, J. T., and Murray, G.: Neodymium:YAG lasers. An FDA report. Ophthalmology 92:209, 1985. 7. Flohr, M. J., Robin, A.L., and Kelley, J. S.: Early complications following Q-switched neodymium-YAG laser posterior capsulotomy. Ophthalmology 92:360, 1985. 8. Kraff, M. C.; Sanders, D. R., and Lieberman, H. 1.: Intraocular pressure and the corneal endothelium after neodymium:YAG laser posterior capsulotomy. Arch. Ophthalmol. 103:511, 1985. 9. Boniuk, M.: Comments about the posterior capsule. In Emery, J. M., and Jacobson, A. C. (eds.): Current Concepts in Cataract Surgery. Selected Proceedings of the Sixth Biennial Cataract Surgical Congress. St. Louis, C. V. Mosby, 1980, pp. 297 and 298. 10. Callahan, M. A.: Complications after capsulotomy following Kelman phacoemulsification. In Emery, J. M., and Jacobson, A. C. (eds.): Current Concepts in Cataract Surgery. Selected Proceedings of the Sixth Biennial Cataract Surgical Congress. St. Louis, C. V. Mosby, 1980, pp. 298-304. 11. Ad Hoc Committee on Ophthalmic Procedures Assessment: Academy recommendation. Ophthalmology 91:539, 1984. 12. Bourne, W. M., Liesegang, T. J., Waller, R. R., and Ilstrup, D. M.: The effect of sodium hyaluronate on endothelial cell damage during extracapsular cataract extraction and posterior lens implantation. Am. J. Ophthalmol. 98:759, 1984. 13. Seward, H. c.. and Doran, R. M. 1.: Posterior capsulotomy and retinal detachment following extracapsular lens surgery. Br. J. Ophthalmol. 68:379, 1984. 14. Pearce, J. 1.: Modern simple extracapsular surgery. Trans. Ophthalmol. Soc. U.K. 99:176, 1979. 15. Wilhelmus, K. R., and Emery, J. M.: Posterior capsule opacification following phacoemulsification. Ophthalmic Surg. 11:264, 1980. 16. Park, D. W., II, and Emery, J. M.: Cystoid macular edema after discission. Primary vs. secondary. In Emery, J. M., and Jacobson, A. C. (eds.): Current Concepts in Cataract Surgery. Selected Proceedings of the Seventh Biennial Cataract Surgical Congress. Norwalk, Appleton-Century-Crofts, 1982, pp. 237-241. 17. Wilhelmus, K. R., and Emery, J. M.: Posterior capsular opacification following phacoemulsification. In Emery, J. M., and Jacobson, A. C. (eds.): Current Concepts in Cataract Surgery. Selected Proceedings of the Sixth Biennial Cataract Surgical Congress. St. Louis, C. V. Mosby, 1980, pp. 304-308.
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18. Channell, M. M., and Beckman, H.: Intraocular pressure changes after neodymium:YAG laser posterior capsulotomy. Arch. Ophthalmol. 102:1024, 1984. 19. Parker, W. T., Clorfeine, G. S., and Stocklin, R. D.: Marked intraocular pressure rise following Nd:YAG laser capsulotomy. Ophthalmic Surg. 15:103, 1984. 20. Richter, C. U., Arzeno, F., Pappas, H. R., Steinert, R. F., Puliafito, C.; and Epstein, D. 1.: Intraocular pressure elevation following Nd:YAG laser posterior capsulotomy. Ophthalmology 92:636, 1985. 21. Keates, R. H., Steinert, R. F., Puliafito, C. A., and Maxwell, S. K.: Long-term followup of Nd:YAG laser posterior capsulotomy. J. Am. Intraocul. Implant Soc. 10:164, 1984. 22. Hoffer, K. J.: YAG and lOP. Ophthalmic Surg. 15:610, 1984. 23. Khodadoust, A. A., Arkfeld, D. F., Caprioli, J., and Sears, M. 1.: Ocular effect of neodymiumYAG laser. Am. J. Ophthalmol. 98:144, 1984. 24. Lerman, S., Thrasher, B., and Moran, M.: Vitreous changes after neodymium-VAG laser irradiation of the posterior lens capsule or mid-vitreous. Am. J. Ophthalmol. 97:470, 1984. 25. Terry, A. c., Stark, W. J., Newsome, D. A., Maumenee, A. E., and Pine, E.: Tissue toxicity of laser-damaged intraocular lens implants. Ophthalmology 92:414, 1985. 26. Kurata, F., Krupin, T., Sinclair, S., and Karp, 1.: Progressive glaucomatous visual field loss after neodymium-VAG laser capsulotomy. Am. J. Ophthalmol. 98:632, 1984. 27. Blackwell, c.. Hirst, 1. W., and Kinnas, S. J.: Neodymium-YAG capsulotomy and potential blindness. Am. J. Ophthalmol. 98:521, 1984. 28. Lindstrom, R. 1., and Harris, W. S.: Management of the posterior capsule following posterior chamber lens implantation. J. Am. Intraocul. Implant Soc. 6:255, 1980. 29. Livernois, R., and Sinskey, R. M.: Complications of later capsulotomy. J. Am. Intraocul. Implant Soc. 7:242, 1981. 30. Fastenberg, D. M., Schwartz, P. 1., and Lin, H. Z.: Retinal detachment following neodymiumYAG laser capsulotomy. Am. J. Ophthalmol. 97:288, 1984. 31. McPherson, A. R., O'Malley, R. E., and Bravo, J.: Retinal detachment following later posterior capsulotomy. Am. J. Ophthalmol. 95:593, 1983. 32. Meyer, K. T., Pettit, T. H., and Straatsma, B. R.: Corneal endothelial damage with neodymium:YAG laser. Ophthalmology 91:1022, 1984. 33. Peyman, G. A., Kraff, M., and Viherkoski, E.: Noninvasive capsulectomy using a new pulsed infrared laser. J. Am. Intraocul. Implant Soc. 8:239, 1982. 34. Puliafito, C. A., and Steinert, R. F.: Experimental lens laser surgery. In Trokel, S. 1. (ed.): YAG Laser Ophthalmic Microsurgery. Norwalk, Appleton-Century-Crofts, 1983, pp. 93-100.