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Suture to limbus distances in eyes with a posterior chamber intraocular lens implanted by scleral fixation
Suture to limbus distances in eyes with a posterior chamber intraocular lens implanted by scleral fixation Jin Hak Lee, M.D., Ph.D., Jin Ho Chang, M.D.
ABSTRACT This study used linear regression to analyze the correlation between the location of transscleral sutures and the postoperative visual acuity, refraction, and anterior chamber depth in eyes with posterior chamber intraocular lenses implanted by scleral fixation. The suture-to-limbus distance at the 12 o'clock and 6 o'clock positions averaged 2.4 mm and 1.7 mm, respectively. Suture location had no statistically significant relationship with postoperative acuity, spherical equivalent, astigmatism, or anterior chamber depth. Key Words: astigmatism, posterior chamber intraocular lens, scleral fixation, suture-to-limbus distance, visual acuity
Extracapsular cataract extraction (ECCE) with the implantation of a posterior chamber intraocular lens (IOL) is a standard treatment for cataracts. 1- 3 Because it was impossible to implant a posterior chamber lens in eyes that had had intracapsular cataract extraction or in which the posterior capsule or zonule was damaged during ECCE, an anterior chamber intraocular lens was used in the majority of such cases. But anterior chamber IOLs are closer to the corneal endothelium, iris, and trabecular meshwork and are reported to cause various complications. 4 •5 Recent reports have discussed transscleral fixation of posterior chamber IOLs in the absence of zonular/capsular support. 6•7 But the tilt and decentration of the optic of the IOL are assumed to have a deleterious effect on postoperative refraction and visual acuity. In addition the surgeon cannot directly see the ciliary sulcus intraoperatively and uses the corneoscleral limbus as an anatomic landmark. Thus the distance from the corneoscleral limbus to the transscleral fixation suture may affect postoperative anterior chamber depth and postoperative visual acuity and refraction. We investigated the correlation between the tilt of the optic and postoperative vision and astigmatism and between the suture-to-limbus distance and postoperative anterior chamber depth and spherical equivalent in eyes
with a posterior chamber IOL implanted by scleral fixation.
SUBJECTS AND METHODS We studied 18 eyes of 18 patients who had a posterior chamber IOL implanted by scleral fixation between 1989 and 1990 at Seoul National University Hospital by a single surgeon (J.H.L.). Follow-up was more than four months (Table 1). Sixteen patients were male and two were female; ages ranged from 20 years to 84 years (average 49). Preoperatively, six eyes were cataractous and 12 aphakic. Four cataracts were of senile origin and two were traumatic. Except for some capsule residue, the lens material of one aphakic eye had been spontaneously absorbed after trauma. The other aphakic eyes had cataract extraction because of senile cataracts. One had had capsular discission by neodymium: VAG laser after the surgery. Preoperative visual acuity was below 20/66 in the cataract group and averaged 20/30 in the aphakic group. Postoperative acuity averaged 20/21 in the cataract group and 20/23 in the aphakic group. Patients were admitted to the hospital two days before surgery and had their vision checked and refraction, keratometry, and axial length measured with a Welch Allyn retinoscope, Bausch & Lomb keratometer, and
Presented in part at the Fourth International Cataract, Implant, Microsurgical and Refractive Keratoplasty Meeting, Seoul, Korea, May 1991. Reprint requests to lin Hak Lee. M.D., Department of Ophthalmology, College of Medicine. Seoul National University Hospital, Yongon-Dong 28. Chongno-Gu, Seoul110-744, Korea.
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Table 1. Patient profiles.
Postoperative
Months After Surgery
20/20
19
Visual Acuity Patient
Sex
Age
Diagnosis
I
M
38
Aphakia
20/20
2 3
M M
61 20
Aphakia
20/100
20/20
15
Aphakia
20/50
20/30
II
4
M
25
Aphakia
20/20
20/20
10
10
Preoperative
5
F
73
Aphakia
20/330
20/100
6
M
39
Aphakia
20/22
20/15
9
7
M
68
Aphakia
20/50
20/30
8
8
M
54
Aphakia
20/30
20/22
7
9
M
20
Aphakia
20/40
20/30
5
10
M M
64
20/20
4
54
Aphakia Aphakia
20/20
II
20/25
20/20
4
12
M
54
Aphakia
20/30
20/22
4
13 14
M M
15 16
F M
51
Cataract
20/60
20/15
19
58 61
Cataract
20/250 20/2000
20/25
12
20/20
8
20/22 20/22
8 9
20/100
6
39
Cataract Cataract
17
M
35
Cataract
FC/10 em HM
18
M
84
Cataract
20/2000
Humphrey biometry analyzer, respectively. The posterior chamber IOL power was calculated using Binkhorst 8 and SRK9 formulas aiming for 0.5 to 1.0 diopters (D) of myopia. 10 If the visual acuity of the fellow eye was good and its refractive anomaly significant, the IOL power was selected to reduce ametropia. The surgeon implanted three-piece posterior chamber IOLs with polypropylene haptics. The IOLs were posteriorly angulated by ten degrees. Scleral fixation was performed by the one-needle6 or two-needle 6 • 11 - 13 technique. In the one-needle technique, the surgeon passes a 23-gauge or 25-gauge needle through the sclera at the level of the ciliary sulcus at 12 o'clock to traverse the posterior chamber and exit at 6 o'clock at the level of the ciliary sulcus. In the two-needle technique, the surgeon makes a separate suture at 12 o'clock and 6 o'clock using a needle such as the CIF-4, 26-gauge hypodermic and 9-0 or 10-0 polypropylene (Prolene®) sutures. Until the end of 1989, when Duffey and coauthors 14 reported a study of transsclerally sutured IOL implantation, we tried to place the sutures 3.0 mm from the limbus to fixate the IOL in the pars plana. After that we tried to place the suture 1.0 mm from the limbus to fixate the IOL in the ciliary sulcus, but the actual postoperative measurement ranged from 1.1 mm to 3.4 mm in the 3.0 mm group (mean = 2.2 mm) and from 1.1 mm to 1.0 mm in the 1.0 mm group (mean = 1.6 mm). The actual distances can be seen as a continuous spectrum regardless of the aim because we found no difference between the 3.0 mm and 1.0 mm groups.
More than four months after surgery, we measured visual acuity, refraction, keratometry, axial length, and anterior chamber depth. The distances from the corneosclerallimbus to the 9-0 Prolene suture at 12 o'clock (dd and 6 o'clock (d 6 ) were recorded using a Mcintyre lens. The correlation between the mean of d 12 , d6 , and anterior chamber depth and the spherical equivalent was analyzed by linear regression. The difference in spherical equivalent (dSE) was calculated by subtracting the aimed spherical equivalent from postoperative spherical equivalent. The correlation of the difference between d 12 and d6 to vision and astigmatism was investigated using the same method.
One-Needle Technique
Preoperatively, the pupil of the eye was dilated with 10% phenylephrine hydrochloride and 1% tropicamide eyedrops. The patient was given intravenous 15% mannitol to dehydrate the vitreous. A fornix-based conjunctival flap was made from 11 o'clock to 1 o'clock along with another small conjunctival flap at 6 o'clock. Bleeding was controlled with wet-field cauterization. A 23-gauge hypodermic needle or 25-gauge spinal needle was inserted into the sclera behind the comeosclerallimbus at 12 o'clock and advanced behind the iris, piercing the sclera at 6 o'clock under the conjunctival flap. A 9-0 Prolene suture was threaded into the needle and both were withdrawn. A corneoscleral groove was made with a #64 Beaver knife from 11 o'clock to 1 o'clock and an anterior chamber paracentesis done
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with a razor blade at ll o'clock. Sodium hyaluronate (Healon®) was injected into the anterior chamber. The paracentesis was extended into the corneoscleral incision 7 mm in chord length. A Sinskey hook was introduced into the anterior chamber and a 9-0 Prolene suture was hooked through the pupil. A loop of it was pulled from the anterior chamber through the corneoscleral incision. The suture was severed midway outside the anterior chamber; both ends were separately tied to the IOL's two haptics. The IOL was inserted into the posterior chamber by pulling on the suture at 6 o'clock. The suture threads were fixated at the sclera using one bite of anchoring suture at each side. The corneoscleral incision was closed with l 0-0 nylon and the conjunctiva with 8-0 polyglactin (Vicryl®). Gentamicin sulfate 20 mg and methylprednisolone acetate (Depo-Medrol®) 20 mg were injected subconjunctivally and the eye dressed with kanamycin sulfate ophthalmic ointment.
Two-Needle Technique
Until the corneoscleral groove was made, the twoneedle procedure was the same as the one-needle. The corneoscleral groove was made with a #64 Beaver knife from ll o'clock to l o'clock, and anterior chamber paracentesis was done with a razor blade at ll o'clock. Healon was injected into the anterior chamber. The anterior chamber paracentesis site was extended into the corneoscleral incision 7 mm in chord length. A 26-gauge hypodermic needle was inserted through the corneoscleral incision and advanced through the pupil and behind the iris, piercing the sclera at 6 o'clock under the conjunctival flap. A 9-0 or l 0-0 Prolene suture was threaded into the needle and the needle was withdrawn with the suture, which was tied to the IOL's inferior haptic. A transpupillary bite was done with another Prolene suture at 12 o'clock, piercing the sclera inside out approximately at the ciliary sulcus level. The end of the second suture was tied to the superior haptic and the IOL inserted into the posterior chamber by pulling on the suture at 6 o'clock. Alternately, two separate sutures were passed at 12 o'clock and 6 o'clock using a CIF-4 needle after the corneoscleral incision and the two sutures were tied to each haptic. The suture threads were fixated at the sclera using one bite of anchoring suture at each side. The corneoscleral incision was closed with l 0-0 nylon and the conjunctiva with 8-0 Vi cry!. Gentamicin sulfate 20 mg and Depo-Medrol 20 mg were injected subconjunctivally and a kanamycin sulfate ophthalmic ointment dressing applied.
Table 2. Distance (mm) from corneosclerallimbus to the fixation sutures at 12 o'clock (dn) and 6 o'clock (d6 ). Patient
dn
d6
I
3.0 2.7 2.5 2.7 2.7 2.3 2.4 2.5 2.5 1.5 2.3 1.1 2.7 2.5 3.4 2.0 2.7
1.1 2.4 1.6 2.0 1.8 1.6 1.7 1.5 1.6 1.7 1.5
2 3 4 5 6 7 8 9 10 II
12 13 14 15 16 17 18
Mean Distance
Difference
2.1 2.6 2.1 2.4 2.3 2.0 2.1 2.0 2.1 1.6 1.9 1.1 2.5 1.8 3.0 1.8 2.4 1.8
1.9 0.3 0.9 0.7 0.9 0.7 0.7 1.0 0.9 -0.2 0.8 0.0 0.5 1.4 0.9 0.5 0.7 -0.5
1.1
2.2 1.1 2.5 1.5 2.0 2.0
1.5
chamber depth ranged from 3.63 mm to 5.31 mm (average= 4.35 mm, Table 3). Postoperative best corrected visual acuity ranged from 20/200 to 20/17 (average = 20/24, Table l); dSE ranged from -2.50 D to 1.12 D (average= -0.35 D, Table 3). There was no statistically significant relationship between mean distances and anterior chamber depth nor between the mean distances and vision or dSE. The difference in the distances was calculated by subtracting d6 from d 12 and assumed to reflect the vertical tilt of the optic and ranged from -0.5 to 1.9 mm (average = 0.7 mm) (Figures 4 and 5; Table 2). The connection between the distance difference and postoperative astigACD(mm)
6.00
4.00
•
.•...•• •••••
•
2.00
RESULTS Table 2 shows the distances from the corneoscleral limbus to the fixation suture; d 12 ranged from 1.1 mm to 3.4 mm (average = 2.4 mm) and d6 ranged from 1.1 mm to 2.5 mm (average= 1.7 mm). The mean of the distances ranged from 1.1 to 3.0 mm (average = 2.1 mm) (Figures l to 3; Table 2). Anterior 280
o.oo,+----~---~---
o.o
1.0
2.0
3.0
M(mm)
Fig. I.
(Lee) The relationship between mean distances (M) and anterior chamber depth (ACD). There was no statistically significant relationship between them.
J CATARACT REFRACT SURG-VOL 19, MARCH 1993
visual acuity
2.0 1.5
•
1.0 0.5
• • • •••• •• •• • I
• •
0.0
0.0
1.0
2.0
(Lee) The relationship between mean distances (M) and visual acuity. There was no significant relationship between them.
dSE(D)
2.00
•
1.00 0.00 -1.00
•• •• • • •• • • • •• • • .
-2.00 -3.00 0.0
1.0
2.0
.
•
3.0 M(mm)
Fig. 3.
(Lee) The difference in spherical equivalent (dSE) is plotted against mean distance (M). There was no significant relationship between them.
Visual acuity
2.0 1.5
••
• • • • ••••
1.0 0.5
•
•• •
•
•
0.0 +-----~---~-----, -1.0 0.0 1.0 2.0 D(mm)
Fig. 4.
DISCUSSION
3.0 M(mm)
Fig. 2.
-1.91 D to 2.38 D (average = 0.81 D) and was significantly (P < .05) linked to postoperative astigmatism (Figure 6, Table 3). Multiple linear regression analysis of the difference in the distances, perioperative change of keratometric measurements, and postoperative astigmatism revealed no significant relationship between the difference and postoperative astigmatism.
(Lee) The relationship between the distance differences (D) and visual acuity. There was no significant relationship between them.
matism was investigated. With-the-rule astigmatism was labeled as negative cylinder and against-the-rule astigmatism as positive cylinder and they ranged from -6.00 to 3.50 D. Linear regression analysis revealed no significant relationship between difference of distances and postoperative astigmatism and visual acuity. Perioperative change ofkeratometric measurements ranged from
A posterior chamber IOL was implanted by scleral fixation with sutures at 12 o'clock and 6 o'clock in 18 eyes of 18 patients. The IOL tilted or decentered frequently intraoperatively causing the surgeon to adjust suture tension or manipulate in the anterior chamber with instruments such as a Sinskey hook. Reports have indicated that fixating a posterior chamber IOL at two points causes the IOL to tilt or decenter, which could negatively affect vision and refraction. 6 • 15 A three-point posterior chamber IOL fixation has been reported to prevent these complications. 15 Yet the threepoint fixation requires more manipulation near the vitreous base and the peripheral retina and is more likely to cause a hemorrhage from the vessel-rich ciliary body . On the other hand, Duffey and coauthors 14 reported that passing a transscleral suture per haptic achieved a good IOL position. Our study shows that the tilt or decentration caused by two-point fixation had little effect on postoperative vision and astigmatism. Holladay 16 found that with ECCE and posterior chamber IOL implantation using the conventional method, decentration greater than I mm caused radial astigmatism and tilt greater than 15 degrees caused a coma aberration, neither of which could be corrected with conventional eyewear. But Lakshminarayanan et al. 17 found that implanting a posterior chamber IOL did not cause a statistically significant increase in refractive astigmatism in the postoperative eye and that the magnitude of induced astigmatism in almost all cases was less than 0.50 D against-the-rule astigmatism . Auran and coauthors 18 carried out an in-vivo study in patients who had had the same procedure and concluded that there was no significant relationship between tilt or decentration of the posterior chamber IOL and vision nor between tilt-induced cylinder and residual astigmatism. Technically, implanting a posterior chamber IOL by scleral fixation differs considerably from the conventional ECCE and posterior chamber IOL implantation in that the position and tilt of the IOL are determined by the location of the transscleral suture. But optical properties of the two procedures are similar and the results of Lakshminarayanan et al. and Auran and coauthors agree with ours. Our study revealed that with two-point fixation of a posterior chamber IOL, the suture location did not influence postoperative vision and astigmatism as long as d 12 was in the range of 1.1 mm and 3.4 mm, d 6 in the range of 1.1 mm and 2.5 mm, mean distance in the range
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Table 3. Biometric values of the enrolled cases. Postoperative AstigmaPatient tism (D)
I 2 3 4 5 6 7 8 9 10 II 12 13 14 15 16 17 18
-0.25 0.75 -4.50 0.50 -6.00 -1.50 -3.50 -2.50 0.00 -0.25 2.50 3.50 -0.50 0.00 -3.00 -0.50 -3.00 -1.00
Aimed
Actual
-0.13 -0.53 -0.49 -0.52 -0.44 -0.20 -0.25 -0.02 -0.23 -0.50 -0.59 -0.58 -0.40 -0.08 -0.44 0.00 -0.97 -1.62
-0.13 -1.88 -0.25 -0.25 -2.00 0.75 -2.75 -0.75 -2.00 -0.13 -0.75 0.75 -0.25 0.00 -0.50 -1.25 -2.50 -0.50
Vertical Horizontal (H) V - H (V)
dSE*
0.00 41.00 41.00 -1.35 43.75 43.00 0.24 45.75 43.38 0.27 42.25 42.25 -1.56 47.50 44.50 0.95 45.00 43.50 -2.50 43.88 43.75 -0.73 42.15 41.49 -1.77 48.50 47.25 0.37 43.25 44.50 -0.16 42.50 44.25 1.33 43.75 44.25 0.15 42.13 42.38 0.08 43.50 43.50 -0.06 44.00 41.33 -1.25 42.88 42.13 -1.53 43.00 42.00 1.12 43.75 42.75
0.00 0.75 2.38 0.00 3.00 1.50 0.13 0.66 1.25 -1.25 -1.75 -0.50 -0.25 0.00 2.67 0.75 1.00 1.00
Mean
41.00 43.38 44.56 42.25 46.00 44.25 43.81 41.82 47.88 43.88 43.38 44.00 42.26 43.50 42.67 42.50 42.50 43.25
Anterior Chamber Depth DMeant (mm)
Postoperative Keratometry (D)
Preoperative Keratometry (D)
Spherical Equivalent (D)
Vertical Horizontal (H) V - H (V)
43.00 43.30 46.87 43.60 49.00 46.60 44.50 43.00 49.25 44.50 43.14 42.64 42.00 43.75 44.25 43.83 43.63 45.25
D(V H)t
Mean
42.00 1.00 42.50 1.00 1.50 42.50 0.80 42.90 0.05 -0.48 42.12 4.75 44.50 2.37 -0.07 1.33 0.69 1.33 42.94 42.27 43.87 5.13 46.44 2.13 0.44 44.20 2.40 45.40 0.90 1.15 1.12 0.06 1.25 43.88 43.25 1.34 0.18 41.00 2.00 42.00 1.00 0.25 47.00 2.25 48.13 1.50 0.50 44.25 0.25 44.38 45.05 -1.91 44.10 -0.16 0.72 45.05 -2.41 43.85 -1.91 -0.16 43.00 -1.00 42.50 -0.75 0.24 1.00 -0.25 1.00 43.25 42.75 42.25 2.00 43.25 -0.67 0.59 1.73 42.96 0.98 0.46 42.10 1.55 -0.15 41.08 2.55 42.35 1.75 0.63 42.50 2.75 43.88
3.96 4.16 4.70 5.24 3.63 4.23 3.96 4.43 4.10 4.30 4.77 3.69 5.31 4.03 3.90 4.43 5.17 4.30
• dSE = actual spherical equivalent - aimed spherical equivalent
t D(V - H) = (postop V - H) - (preop V - H) f DMean = postop mean - preop mean
Astigmatism( D)
0.00
·4.00
Astigmatism( D)
•
4.00
• •
•
4.00 •
• • •• • •
•
•
0.0
• •
0.00
I •
• •
·4.00
1.0
(Lee) The relationship between the distance differences (D) and cylinder. There was no statistically significant relationship between them.
of 1.1 mm and 3.0 mm, and distance difference between -0.5 mm and 1.9 mm. But Duffey and coauthors 14 reported that in postmortem eye sutures had to be passed within 1 mm of the posterior surgical limbus to allow implantation of the IOL in the ciliary sulcus, which seems more logical. Yet Lubniewski et al. 19 in their postmortem histological study observed that current surgical technique did not guarantee the ciliary sulcus fixation of the haptic. We did not emphasize exact placement of the transscleral fixation suture within 1 mm of 282
••
I
•
•••
• •
-s.oo+---.---~-~--~---.
2.0
·2.00
·1.00
D(mm)
Fig. 5.
•
•
-s.oo+----~----.----__,
·1.0
•
0.00
1.00
2.00
3.00
Change in keratometry(D)
Fig. 6.
(Lee) Perioperative change of keratometric measurements was significantly linked (P< .05) to postoperative astigmatism.
the corneosclerallimbus. Because the transscleral suture is easily cut by the corneoscleral suture when it is placed I mm from the limbus, it seems appropriate to pass the suture 2 mm from the posterior surgical limbus. Mean distance was defined as the mean of d 12 and d6 • The larger d 12o d6 are (i.e., the more posterior to the corneosclerallimbus the fixation sutures are passed and the larger the mean distance), the farther posteriorly the IOL is located. Therefore, the anterior chamber becomes deeper and the eye more hyperopic. But since posterior
J CATARACT REFRACTSURG-VOL 19. MARCH 1993
chamber IOL haptics are posteriorly angulated by ten degrees, we can also assume that the more posterior the fixation sutures are passed to the comeoscleral limbus and the larger the mean distance, the more stretched the IOL haptics and the more anteriorly displaced the IOL optic. This study revealed that the location of fixation sutures did not influence postoperative anterior chamber depth and dSE as long as d 12 ranged from l.l mm to 3.4 mm, d 6 ranged from 1.1 mm to 2.5 mm, mean distance ranged from 1.1 mm to 3.0 mm, and distance difference was between -0.5 mm and 1.9 mm. In other words, if the fixation sutures were passed between 1.1 mm and 3.4 mm from the comeoscleral limbus, postoperative anterior chamber depth and refraction did not change significantly in relation to the suture-tolimbus distance change. The distance difference represented the degree of the tilt but the horizontal and oblique tilt were not considered. Scleral fixation of the IOL may cause greater degree of tilt than conventional ECCE and posterior chamber IOL implantation because of inadequate support from the posterior capsule and zonule, but the tilt may have little effect on postoperative vision and astigmatism in these casesP· 18 The subject needs further investigation. REFERENCES I. Stark WJ, Leske MC, Worthen OM, Murray GC. Trends in cataract surgery and intraocular lenses in the United States. Am J Ophthalmol 1983; 96:304-310 2. Stark WJ, Terry AC, Worthen D, Murray GC. Updates of intraocular lenses implanted in the United States. Am J Ophthalmol 1984; 98:238-239 3. Kim MS, Park JJ, Huh W, Kim JH. 1,073 cases of intraocular lens implantation. J Korean Ophthalmol Soc 1986; 27:157-167 4. Apple DJ, Mamalis N, Loftfield K, et al. Complications of intraocular lenses. A historical and histopathological review. Surv Ophthalmol 1984; 29: 1-54 5. Smith PW, Wong SK, Stark WJ, et al. Complications of semiflexible, closed-looped anterior chamber intraocular lenses. Arch Ophthalmol 1987; 105:52-57
6. Hu BV, Shin DH, Gibbs KA, Hong YJ. Implantation of posterior chamber lens in the absence of capsular and zonular support. Arch Ophthalmol 1988; I 06:416-420 7. Stark WJ, Goodman G, Goodman D, Gottsch J. Posterior chamber intraocular lens implantation in the absence of posterior capsular support. Ophthalmic Surg 1988; 19: 240-243 8. Binkhorst RD. Intraocular Lens Power Calculation Manual-A Guide to the Author's TI-58151 IOL Power Module, 2nd ed. New York, RD Binkhorst, 1981 9. Retzlaff J, Sanders D, Kraff M. A Manual of Implant Power Calculation. Medford, OR, Retzlaff, Sanders, and Kraft, 1981 I 0. Datiles MB, Gancayco T. Low myopia with low astigmatic correction gives cataract surgery patients good depth of focus. Ophthalmology 1990; 97:922-926 II. Spigelman AV, Lindstrom RL, Nichols BD, et al. Implantation of a posterior chamber lens without capsular support during penetrating keratoplasty or as a secondary lens implant. Ophthalmic Surg 1988; 19:396-398 12. Lindquist TD, Lane SS, Agapitos PJ, et al. Transscleral fixation of posterior chamber intraocular lenses in the absence of capsular support. Ophthalmic Surg 1989; 20: 769-775 13. Chang JH, Lee JH. Implantation of posterior chamber intraocular lenses by suture fixation without capsular and zonular support. Korean J Ophthalmol 1989; 3:90-93 14. Duffey RJ, Holland EJ, Agapitos PJ, Lindstrom RL. Anatomic study oftranssclerally sutured intraocular lens implantation. Am J Ophthalmol 1989; 108:300-309 15. Johnson SM. Results of exchanging anterior chamber lenses with sulcus-fixated posterior chamber IOLs without capsular support in penetrating keratoplasty. Ophthalmic Surg 1989; 20:465-468 16. Holladay JT. Evaluating the intraocular lens optic. Surv Ophthalmol 1986; 30:385-390 17. Lakshminarayanan V, Enoch JM, Raasch T, et al. Refractive changes induced by intraocular lens tilt and longitudinal displacement. Arch Ophthalmol 1986; I 04:9092 18. Auran JD, Koester CJ, Donn A. In vivo measurement of posterior chamber intraocular lens decentration and tilt. Arch Ophthalmol 1990; 108:75-79 19. Lubniewski AJ, Holland EJ, Van Meter WS, et al. Histologic study of eyes with transsclerally sutured posterior chamber intraocular lenses. Am J Ophthalmol 1990; II 0: 237-243
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ABSTRACT This study used linear regression to analyze the correlation between the location of transscleral sutures and the postoperative visual acuity, refraction, and anterior chamber depth in eyes with posterior chamber intraocular lenses implanted by scleral fixation. The suture-to-limbus distance at the 12 o'clock and 6 o'clock positions averaged 2.4 mm and 1.7 mm, respectively. Suture location had no statistically significant relationship with postoperative acuity, spherical equivalent, astigmatism, or anterior chamber depth. Key Words: astigmatism, posterior chamber intraocular lens, scleral fixation, suture-to-limbus distance, visual acuity
Extracapsular cataract extraction (ECCE) with the implantation of a posterior chamber intraocular lens (IOL) is a standard treatment for cataracts. 1- 3 Because it was impossible to implant a posterior chamber lens in eyes that had had intracapsular cataract extraction or in which the posterior capsule or zonule was damaged during ECCE, an anterior chamber intraocular lens was used in the majority of such cases. But anterior chamber IOLs are closer to the corneal endothelium, iris, and trabecular meshwork and are reported to cause various complications. 4 •5 Recent reports have discussed transscleral fixation of posterior chamber IOLs in the absence of zonular/capsular support. 6•7 But the tilt and decentration of the optic of the IOL are assumed to have a deleterious effect on postoperative refraction and visual acuity. In addition the surgeon cannot directly see the ciliary sulcus intraoperatively and uses the corneoscleral limbus as an anatomic landmark. Thus the distance from the corneoscleral limbus to the transscleral fixation suture may affect postoperative anterior chamber depth and postoperative visual acuity and refraction. We investigated the correlation between the tilt of the optic and postoperative vision and astigmatism and between the suture-to-limbus distance and postoperative anterior chamber depth and spherical equivalent in eyes
with a posterior chamber IOL implanted by scleral fixation.
SUBJECTS AND METHODS We studied 18 eyes of 18 patients who had a posterior chamber IOL implanted by scleral fixation between 1989 and 1990 at Seoul National University Hospital by a single surgeon (J.H.L.). Follow-up was more than four months (Table 1). Sixteen patients were male and two were female; ages ranged from 20 years to 84 years (average 49). Preoperatively, six eyes were cataractous and 12 aphakic. Four cataracts were of senile origin and two were traumatic. Except for some capsule residue, the lens material of one aphakic eye had been spontaneously absorbed after trauma. The other aphakic eyes had cataract extraction because of senile cataracts. One had had capsular discission by neodymium: VAG laser after the surgery. Preoperative visual acuity was below 20/66 in the cataract group and averaged 20/30 in the aphakic group. Postoperative acuity averaged 20/21 in the cataract group and 20/23 in the aphakic group. Patients were admitted to the hospital two days before surgery and had their vision checked and refraction, keratometry, and axial length measured with a Welch Allyn retinoscope, Bausch & Lomb keratometer, and
Presented in part at the Fourth International Cataract, Implant, Microsurgical and Refractive Keratoplasty Meeting, Seoul, Korea, May 1991. Reprint requests to lin Hak Lee. M.D., Department of Ophthalmology, College of Medicine. Seoul National University Hospital, Yongon-Dong 28. Chongno-Gu, Seoul110-744, Korea.
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Table 1. Patient profiles.
Postoperative
Months After Surgery
20/20
19
Visual Acuity Patient
Sex
Age
Diagnosis
I
M
38
Aphakia
20/20
2 3
M M
61 20
Aphakia
20/100
20/20
15
Aphakia
20/50
20/30
II
4
M
25
Aphakia
20/20
20/20
10
10
Preoperative
5
F
73
Aphakia
20/330
20/100
6
M
39
Aphakia
20/22
20/15
9
7
M
68
Aphakia
20/50
20/30
8
8
M
54
Aphakia
20/30
20/22
7
9
M
20
Aphakia
20/40
20/30
5
10
M M
64
20/20
4
54
Aphakia Aphakia
20/20
II
20/25
20/20
4
12
M
54
Aphakia
20/30
20/22
4
13 14
M M
15 16
F M
51
Cataract
20/60
20/15
19
58 61
Cataract
20/250 20/2000
20/25
12
20/20
8
20/22 20/22
8 9
20/100
6
39
Cataract Cataract
17
M
35
Cataract
FC/10 em HM
18
M
84
Cataract
20/2000
Humphrey biometry analyzer, respectively. The posterior chamber IOL power was calculated using Binkhorst 8 and SRK9 formulas aiming for 0.5 to 1.0 diopters (D) of myopia. 10 If the visual acuity of the fellow eye was good and its refractive anomaly significant, the IOL power was selected to reduce ametropia. The surgeon implanted three-piece posterior chamber IOLs with polypropylene haptics. The IOLs were posteriorly angulated by ten degrees. Scleral fixation was performed by the one-needle6 or two-needle 6 • 11 - 13 technique. In the one-needle technique, the surgeon passes a 23-gauge or 25-gauge needle through the sclera at the level of the ciliary sulcus at 12 o'clock to traverse the posterior chamber and exit at 6 o'clock at the level of the ciliary sulcus. In the two-needle technique, the surgeon makes a separate suture at 12 o'clock and 6 o'clock using a needle such as the CIF-4, 26-gauge hypodermic and 9-0 or 10-0 polypropylene (Prolene®) sutures. Until the end of 1989, when Duffey and coauthors 14 reported a study of transsclerally sutured IOL implantation, we tried to place the sutures 3.0 mm from the limbus to fixate the IOL in the pars plana. After that we tried to place the suture 1.0 mm from the limbus to fixate the IOL in the ciliary sulcus, but the actual postoperative measurement ranged from 1.1 mm to 3.4 mm in the 3.0 mm group (mean = 2.2 mm) and from 1.1 mm to 1.0 mm in the 1.0 mm group (mean = 1.6 mm). The actual distances can be seen as a continuous spectrum regardless of the aim because we found no difference between the 3.0 mm and 1.0 mm groups.
More than four months after surgery, we measured visual acuity, refraction, keratometry, axial length, and anterior chamber depth. The distances from the corneosclerallimbus to the 9-0 Prolene suture at 12 o'clock (dd and 6 o'clock (d 6 ) were recorded using a Mcintyre lens. The correlation between the mean of d 12 , d6 , and anterior chamber depth and the spherical equivalent was analyzed by linear regression. The difference in spherical equivalent (dSE) was calculated by subtracting the aimed spherical equivalent from postoperative spherical equivalent. The correlation of the difference between d 12 and d6 to vision and astigmatism was investigated using the same method.
One-Needle Technique
Preoperatively, the pupil of the eye was dilated with 10% phenylephrine hydrochloride and 1% tropicamide eyedrops. The patient was given intravenous 15% mannitol to dehydrate the vitreous. A fornix-based conjunctival flap was made from 11 o'clock to 1 o'clock along with another small conjunctival flap at 6 o'clock. Bleeding was controlled with wet-field cauterization. A 23-gauge hypodermic needle or 25-gauge spinal needle was inserted into the sclera behind the comeosclerallimbus at 12 o'clock and advanced behind the iris, piercing the sclera at 6 o'clock under the conjunctival flap. A 9-0 Prolene suture was threaded into the needle and both were withdrawn. A corneoscleral groove was made with a #64 Beaver knife from 11 o'clock to 1 o'clock and an anterior chamber paracentesis done
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with a razor blade at ll o'clock. Sodium hyaluronate (Healon®) was injected into the anterior chamber. The paracentesis was extended into the corneoscleral incision 7 mm in chord length. A Sinskey hook was introduced into the anterior chamber and a 9-0 Prolene suture was hooked through the pupil. A loop of it was pulled from the anterior chamber through the corneoscleral incision. The suture was severed midway outside the anterior chamber; both ends were separately tied to the IOL's two haptics. The IOL was inserted into the posterior chamber by pulling on the suture at 6 o'clock. The suture threads were fixated at the sclera using one bite of anchoring suture at each side. The corneoscleral incision was closed with l 0-0 nylon and the conjunctiva with 8-0 polyglactin (Vicryl®). Gentamicin sulfate 20 mg and methylprednisolone acetate (Depo-Medrol®) 20 mg were injected subconjunctivally and the eye dressed with kanamycin sulfate ophthalmic ointment.
Two-Needle Technique
Until the corneoscleral groove was made, the twoneedle procedure was the same as the one-needle. The corneoscleral groove was made with a #64 Beaver knife from ll o'clock to l o'clock, and anterior chamber paracentesis was done with a razor blade at ll o'clock. Healon was injected into the anterior chamber. The anterior chamber paracentesis site was extended into the corneoscleral incision 7 mm in chord length. A 26-gauge hypodermic needle was inserted through the corneoscleral incision and advanced through the pupil and behind the iris, piercing the sclera at 6 o'clock under the conjunctival flap. A 9-0 or l 0-0 Prolene suture was threaded into the needle and the needle was withdrawn with the suture, which was tied to the IOL's inferior haptic. A transpupillary bite was done with another Prolene suture at 12 o'clock, piercing the sclera inside out approximately at the ciliary sulcus level. The end of the second suture was tied to the superior haptic and the IOL inserted into the posterior chamber by pulling on the suture at 6 o'clock. Alternately, two separate sutures were passed at 12 o'clock and 6 o'clock using a CIF-4 needle after the corneoscleral incision and the two sutures were tied to each haptic. The suture threads were fixated at the sclera using one bite of anchoring suture at each side. The corneoscleral incision was closed with l 0-0 nylon and the conjunctiva with 8-0 Vi cry!. Gentamicin sulfate 20 mg and Depo-Medrol 20 mg were injected subconjunctivally and a kanamycin sulfate ophthalmic ointment dressing applied.
Table 2. Distance (mm) from corneosclerallimbus to the fixation sutures at 12 o'clock (dn) and 6 o'clock (d6 ). Patient
dn
d6
I
3.0 2.7 2.5 2.7 2.7 2.3 2.4 2.5 2.5 1.5 2.3 1.1 2.7 2.5 3.4 2.0 2.7
1.1 2.4 1.6 2.0 1.8 1.6 1.7 1.5 1.6 1.7 1.5
2 3 4 5 6 7 8 9 10 II
12 13 14 15 16 17 18
Mean Distance
Difference
2.1 2.6 2.1 2.4 2.3 2.0 2.1 2.0 2.1 1.6 1.9 1.1 2.5 1.8 3.0 1.8 2.4 1.8
1.9 0.3 0.9 0.7 0.9 0.7 0.7 1.0 0.9 -0.2 0.8 0.0 0.5 1.4 0.9 0.5 0.7 -0.5
1.1
2.2 1.1 2.5 1.5 2.0 2.0
1.5
chamber depth ranged from 3.63 mm to 5.31 mm (average= 4.35 mm, Table 3). Postoperative best corrected visual acuity ranged from 20/200 to 20/17 (average = 20/24, Table l); dSE ranged from -2.50 D to 1.12 D (average= -0.35 D, Table 3). There was no statistically significant relationship between mean distances and anterior chamber depth nor between the mean distances and vision or dSE. The difference in the distances was calculated by subtracting d6 from d 12 and assumed to reflect the vertical tilt of the optic and ranged from -0.5 to 1.9 mm (average = 0.7 mm) (Figures 4 and 5; Table 2). The connection between the distance difference and postoperative astigACD(mm)
6.00
4.00
•
.•...•• •••••
•
2.00
RESULTS Table 2 shows the distances from the corneoscleral limbus to the fixation suture; d 12 ranged from 1.1 mm to 3.4 mm (average = 2.4 mm) and d6 ranged from 1.1 mm to 2.5 mm (average= 1.7 mm). The mean of the distances ranged from 1.1 to 3.0 mm (average = 2.1 mm) (Figures l to 3; Table 2). Anterior 280
o.oo,+----~---~---
o.o
1.0
2.0
3.0
M(mm)
Fig. I.
(Lee) The relationship between mean distances (M) and anterior chamber depth (ACD). There was no statistically significant relationship between them.
J CATARACT REFRACT SURG-VOL 19, MARCH 1993
visual acuity
2.0 1.5
•
1.0 0.5
• • • •••• •• •• • I
• •
0.0
0.0
1.0
2.0
(Lee) The relationship between mean distances (M) and visual acuity. There was no significant relationship between them.
dSE(D)
2.00
•
1.00 0.00 -1.00
•• •• • • •• • • • •• • • .
-2.00 -3.00 0.0
1.0
2.0
.
•
3.0 M(mm)
Fig. 3.
(Lee) The difference in spherical equivalent (dSE) is plotted against mean distance (M). There was no significant relationship between them.
Visual acuity
2.0 1.5
••
• • • • ••••
1.0 0.5
•
•• •
•
•
0.0 +-----~---~-----, -1.0 0.0 1.0 2.0 D(mm)
Fig. 4.
DISCUSSION
3.0 M(mm)
Fig. 2.
-1.91 D to 2.38 D (average = 0.81 D) and was significantly (P < .05) linked to postoperative astigmatism (Figure 6, Table 3). Multiple linear regression analysis of the difference in the distances, perioperative change of keratometric measurements, and postoperative astigmatism revealed no significant relationship between the difference and postoperative astigmatism.
(Lee) The relationship between the distance differences (D) and visual acuity. There was no significant relationship between them.
matism was investigated. With-the-rule astigmatism was labeled as negative cylinder and against-the-rule astigmatism as positive cylinder and they ranged from -6.00 to 3.50 D. Linear regression analysis revealed no significant relationship between difference of distances and postoperative astigmatism and visual acuity. Perioperative change ofkeratometric measurements ranged from
A posterior chamber IOL was implanted by scleral fixation with sutures at 12 o'clock and 6 o'clock in 18 eyes of 18 patients. The IOL tilted or decentered frequently intraoperatively causing the surgeon to adjust suture tension or manipulate in the anterior chamber with instruments such as a Sinskey hook. Reports have indicated that fixating a posterior chamber IOL at two points causes the IOL to tilt or decenter, which could negatively affect vision and refraction. 6 • 15 A three-point posterior chamber IOL fixation has been reported to prevent these complications. 15 Yet the threepoint fixation requires more manipulation near the vitreous base and the peripheral retina and is more likely to cause a hemorrhage from the vessel-rich ciliary body . On the other hand, Duffey and coauthors 14 reported that passing a transscleral suture per haptic achieved a good IOL position. Our study shows that the tilt or decentration caused by two-point fixation had little effect on postoperative vision and astigmatism. Holladay 16 found that with ECCE and posterior chamber IOL implantation using the conventional method, decentration greater than I mm caused radial astigmatism and tilt greater than 15 degrees caused a coma aberration, neither of which could be corrected with conventional eyewear. But Lakshminarayanan et al. 17 found that implanting a posterior chamber IOL did not cause a statistically significant increase in refractive astigmatism in the postoperative eye and that the magnitude of induced astigmatism in almost all cases was less than 0.50 D against-the-rule astigmatism . Auran and coauthors 18 carried out an in-vivo study in patients who had had the same procedure and concluded that there was no significant relationship between tilt or decentration of the posterior chamber IOL and vision nor between tilt-induced cylinder and residual astigmatism. Technically, implanting a posterior chamber IOL by scleral fixation differs considerably from the conventional ECCE and posterior chamber IOL implantation in that the position and tilt of the IOL are determined by the location of the transscleral suture. But optical properties of the two procedures are similar and the results of Lakshminarayanan et al. and Auran and coauthors agree with ours. Our study revealed that with two-point fixation of a posterior chamber IOL, the suture location did not influence postoperative vision and astigmatism as long as d 12 was in the range of 1.1 mm and 3.4 mm, d 6 in the range of 1.1 mm and 2.5 mm, mean distance in the range
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281
Table 3. Biometric values of the enrolled cases. Postoperative AstigmaPatient tism (D)
I 2 3 4 5 6 7 8 9 10 II 12 13 14 15 16 17 18
-0.25 0.75 -4.50 0.50 -6.00 -1.50 -3.50 -2.50 0.00 -0.25 2.50 3.50 -0.50 0.00 -3.00 -0.50 -3.00 -1.00
Aimed
Actual
-0.13 -0.53 -0.49 -0.52 -0.44 -0.20 -0.25 -0.02 -0.23 -0.50 -0.59 -0.58 -0.40 -0.08 -0.44 0.00 -0.97 -1.62
-0.13 -1.88 -0.25 -0.25 -2.00 0.75 -2.75 -0.75 -2.00 -0.13 -0.75 0.75 -0.25 0.00 -0.50 -1.25 -2.50 -0.50
Vertical Horizontal (H) V - H (V)
dSE*
0.00 41.00 41.00 -1.35 43.75 43.00 0.24 45.75 43.38 0.27 42.25 42.25 -1.56 47.50 44.50 0.95 45.00 43.50 -2.50 43.88 43.75 -0.73 42.15 41.49 -1.77 48.50 47.25 0.37 43.25 44.50 -0.16 42.50 44.25 1.33 43.75 44.25 0.15 42.13 42.38 0.08 43.50 43.50 -0.06 44.00 41.33 -1.25 42.88 42.13 -1.53 43.00 42.00 1.12 43.75 42.75
0.00 0.75 2.38 0.00 3.00 1.50 0.13 0.66 1.25 -1.25 -1.75 -0.50 -0.25 0.00 2.67 0.75 1.00 1.00
Mean
41.00 43.38 44.56 42.25 46.00 44.25 43.81 41.82 47.88 43.88 43.38 44.00 42.26 43.50 42.67 42.50 42.50 43.25
Anterior Chamber Depth DMeant (mm)
Postoperative Keratometry (D)
Preoperative Keratometry (D)
Spherical Equivalent (D)
Vertical Horizontal (H) V - H (V)
43.00 43.30 46.87 43.60 49.00 46.60 44.50 43.00 49.25 44.50 43.14 42.64 42.00 43.75 44.25 43.83 43.63 45.25
D(V H)t
Mean
42.00 1.00 42.50 1.00 1.50 42.50 0.80 42.90 0.05 -0.48 42.12 4.75 44.50 2.37 -0.07 1.33 0.69 1.33 42.94 42.27 43.87 5.13 46.44 2.13 0.44 44.20 2.40 45.40 0.90 1.15 1.12 0.06 1.25 43.88 43.25 1.34 0.18 41.00 2.00 42.00 1.00 0.25 47.00 2.25 48.13 1.50 0.50 44.25 0.25 44.38 45.05 -1.91 44.10 -0.16 0.72 45.05 -2.41 43.85 -1.91 -0.16 43.00 -1.00 42.50 -0.75 0.24 1.00 -0.25 1.00 43.25 42.75 42.25 2.00 43.25 -0.67 0.59 1.73 42.96 0.98 0.46 42.10 1.55 -0.15 41.08 2.55 42.35 1.75 0.63 42.50 2.75 43.88
3.96 4.16 4.70 5.24 3.63 4.23 3.96 4.43 4.10 4.30 4.77 3.69 5.31 4.03 3.90 4.43 5.17 4.30
• dSE = actual spherical equivalent - aimed spherical equivalent
t D(V - H) = (postop V - H) - (preop V - H) f DMean = postop mean - preop mean
Astigmatism( D)
0.00
·4.00
Astigmatism( D)
•
4.00
• •
•
4.00 •
• • •• • •
•
•
0.0
• •
0.00
I •
• •
·4.00
1.0
(Lee) The relationship between the distance differences (D) and cylinder. There was no statistically significant relationship between them.
of 1.1 mm and 3.0 mm, and distance difference between -0.5 mm and 1.9 mm. But Duffey and coauthors 14 reported that in postmortem eye sutures had to be passed within 1 mm of the posterior surgical limbus to allow implantation of the IOL in the ciliary sulcus, which seems more logical. Yet Lubniewski et al. 19 in their postmortem histological study observed that current surgical technique did not guarantee the ciliary sulcus fixation of the haptic. We did not emphasize exact placement of the transscleral fixation suture within 1 mm of 282
••
I
•
•••
• •
-s.oo+---.---~-~--~---.
2.0
·2.00
·1.00
D(mm)
Fig. 5.
•
•
-s.oo+----~----.----__,
·1.0
•
0.00
1.00
2.00
3.00
Change in keratometry(D)
Fig. 6.
(Lee) Perioperative change of keratometric measurements was significantly linked (P< .05) to postoperative astigmatism.
the corneosclerallimbus. Because the transscleral suture is easily cut by the corneoscleral suture when it is placed I mm from the limbus, it seems appropriate to pass the suture 2 mm from the posterior surgical limbus. Mean distance was defined as the mean of d 12 and d6 • The larger d 12o d6 are (i.e., the more posterior to the corneosclerallimbus the fixation sutures are passed and the larger the mean distance), the farther posteriorly the IOL is located. Therefore, the anterior chamber becomes deeper and the eye more hyperopic. But since posterior
J CATARACT REFRACTSURG-VOL 19. MARCH 1993
chamber IOL haptics are posteriorly angulated by ten degrees, we can also assume that the more posterior the fixation sutures are passed to the comeoscleral limbus and the larger the mean distance, the more stretched the IOL haptics and the more anteriorly displaced the IOL optic. This study revealed that the location of fixation sutures did not influence postoperative anterior chamber depth and dSE as long as d 12 ranged from l.l mm to 3.4 mm, d 6 ranged from 1.1 mm to 2.5 mm, mean distance ranged from 1.1 mm to 3.0 mm, and distance difference was between -0.5 mm and 1.9 mm. In other words, if the fixation sutures were passed between 1.1 mm and 3.4 mm from the comeoscleral limbus, postoperative anterior chamber depth and refraction did not change significantly in relation to the suture-tolimbus distance change. The distance difference represented the degree of the tilt but the horizontal and oblique tilt were not considered. Scleral fixation of the IOL may cause greater degree of tilt than conventional ECCE and posterior chamber IOL implantation because of inadequate support from the posterior capsule and zonule, but the tilt may have little effect on postoperative vision and astigmatism in these casesP· 18 The subject needs further investigation. REFERENCES I. Stark WJ, Leske MC, Worthen OM, Murray GC. Trends in cataract surgery and intraocular lenses in the United States. Am J Ophthalmol 1983; 96:304-310 2. Stark WJ, Terry AC, Worthen D, Murray GC. Updates of intraocular lenses implanted in the United States. Am J Ophthalmol 1984; 98:238-239 3. Kim MS, Park JJ, Huh W, Kim JH. 1,073 cases of intraocular lens implantation. J Korean Ophthalmol Soc 1986; 27:157-167 4. Apple DJ, Mamalis N, Loftfield K, et al. Complications of intraocular lenses. A historical and histopathological review. Surv Ophthalmol 1984; 29: 1-54 5. Smith PW, Wong SK, Stark WJ, et al. Complications of semiflexible, closed-looped anterior chamber intraocular lenses. Arch Ophthalmol 1987; 105:52-57
6. Hu BV, Shin DH, Gibbs KA, Hong YJ. Implantation of posterior chamber lens in the absence of capsular and zonular support. Arch Ophthalmol 1988; I 06:416-420 7. Stark WJ, Goodman G, Goodman D, Gottsch J. Posterior chamber intraocular lens implantation in the absence of posterior capsular support. Ophthalmic Surg 1988; 19: 240-243 8. Binkhorst RD. Intraocular Lens Power Calculation Manual-A Guide to the Author's TI-58151 IOL Power Module, 2nd ed. New York, RD Binkhorst, 1981 9. Retzlaff J, Sanders D, Kraff M. A Manual of Implant Power Calculation. Medford, OR, Retzlaff, Sanders, and Kraft, 1981 I 0. Datiles MB, Gancayco T. Low myopia with low astigmatic correction gives cataract surgery patients good depth of focus. Ophthalmology 1990; 97:922-926 II. Spigelman AV, Lindstrom RL, Nichols BD, et al. Implantation of a posterior chamber lens without capsular support during penetrating keratoplasty or as a secondary lens implant. Ophthalmic Surg 1988; 19:396-398 12. Lindquist TD, Lane SS, Agapitos PJ, et al. Transscleral fixation of posterior chamber intraocular lenses in the absence of capsular support. Ophthalmic Surg 1989; 20: 769-775 13. Chang JH, Lee JH. Implantation of posterior chamber intraocular lenses by suture fixation without capsular and zonular support. Korean J Ophthalmol 1989; 3:90-93 14. Duffey RJ, Holland EJ, Agapitos PJ, Lindstrom RL. Anatomic study oftranssclerally sutured intraocular lens implantation. Am J Ophthalmol 1989; 108:300-309 15. Johnson SM. Results of exchanging anterior chamber lenses with sulcus-fixated posterior chamber IOLs without capsular support in penetrating keratoplasty. Ophthalmic Surg 1989; 20:465-468 16. Holladay JT. Evaluating the intraocular lens optic. Surv Ophthalmol 1986; 30:385-390 17. Lakshminarayanan V, Enoch JM, Raasch T, et al. Refractive changes induced by intraocular lens tilt and longitudinal displacement. Arch Ophthalmol 1986; I 04:9092 18. Auran JD, Koester CJ, Donn A. In vivo measurement of posterior chamber intraocular lens decentration and tilt. Arch Ophthalmol 1990; 108:75-79 19. Lubniewski AJ, Holland EJ, Van Meter WS, et al. Histologic study of eyes with transsclerally sutured posterior chamber intraocular lenses. Am J Ophthalmol 1990; II 0: 237-243
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