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Cataract Formation and Cataract Extraction after Penetrating Keratoplasty
Cataract Formation and Cataract Extraction after Penetrating Keratoplasty Thomas P. Martin, MD, John W. Reed, MD, Claudine Legault, PhD, Sheldon M. Oberfeld, MD, Bradley G. Jacoby, MD, David D. Yu, MD, Alan Dickens, MD, Holly P. Johnson, MD Purpose: This retrospective study was done to identify risk factors for cataract formation and cataract extraction after penetrating keratoplasty to determine whether a combined procedure (simultaneous cataract extraction with keratoplasty) or penetrating keratoplasty alone should be performed. Methods: Variables from 342 phakic eyes having undergone penetrating kerato plasties were studied with univariate and multivariate analyses, including diagnosis, race, sex, age, preoperative lens opacities, preoperative vision, and length of follow-up. Results: For cataract formation, age was the only independent risk factor found by multivariate analysis (P = 0.0001 ). For cataract extraction after penetrating kerato plasty, independent risk factors included age, sex, diagnosis, and preoperative lens opacities (P :$; 0.03). For example, the probability of a 65-year-old patient with Fuchs dystrophy requiring a cataract extraction within 5 years of keratoplasty is 81%. Conclusion: The likelihood of cataract formation and cataract extraction subsequent to penetrating keratoplasty increases greatly after 50 years of age, regardless of the diagnosis leading to the need for keratoplasty. The need for cataract extraction also is increased for female patients, for patients with Fuchs dystrophy, and for those with early preoperative lens opacity. Ophthalmology 1994;101:113-119
Lens opacities are common in older patients requiring penetrating keratoplasty. Whether to perform penetrating keratoplasty alone or in combination with cataract ex traction in the presence of preoperative lens opacities (combined procedure) often is a dilemma for the operating surgeon. Many articles have focused on the relative merits of penetrating keratoplasty with subsequent cataract ex traction versus combined surgery, I-s but little has been published on the incidence of subsequent cataract for mation or of the need for cataract extraction after pene trating keratoplasty. Payant et al 9 reviewed patients with
Fuchs dystrophy and found that cataracts developed in 60% of eyes after penetrating keratoplasty, with 44% re quiring subsequent cataract extraction. Several other au thors have discussed the formation of posterior subcap sular cataracts after penetrating keratoplasty and have re lated them to topical steroid dosage. 10- 13 The objectives ofthis study are to identify the incidence ofand risk factors for ( 1) the formation of cataracts after penetrating kera toplasty, and (2) the need for cataract extraction after ker atoplasty.
Originally received: December 14, 1992. Revision accepted: June 14, 1993. From the Department of Ophthalmology and Department of Public Health Sciences, Bowman Gray School of Medicine of Wake Forest University, Winston-Salem. Presented as a poster at the American Academy of Ophthalmology An nual Meeting, Dallas, November 1992. Reprint requests to John W. Reed, MD, Wake Forest University Eye Center, Medical Center Blvd, Winston-Salem, NC 27157-1033.
Materials and Methods A retrospective review of 1271 eyes that underwent pen etrating keratoplasty consecutively from January 1979 through December 1988 was performed. All penetrating keratoplasties were performed or supervised by one sur geon (JWR). Five hundred eighty-three eyes were phakic before the penetrating keratoplasty; 238 of these phakic
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eyes had visually significant cataracts and underwent cat aract extraction at the time of penetrating keratoplasty. The remaining 345 phakic eyes (278 patients) (i.e., those that did not undergo cataract extraction at the time of keratoplasty) are the focus of this study. Three eyes (2 patients) had incomplete data, leaving a study group of 342 eyes (276 patients). Diagnosis, age, race, sex, preoperative lens opacities, preoperative visual acuity, and length of follow-up were recorded. Associated and independent ocular diseases and previous operations (e.g., glaucoma, amblyopia, branch retinal vein occlusion, trabeculectomy), postoperative complications (e.g., graft rejection, persistent epithelial defect, large postoperative astigmatism), and procedures done postoperatively (e.g., relaxing incisions, YAG cyclo photocoagulation) also were recorded. Initial statistical analyses were performed on 276 eyes ( 1 eye per patient) as well as on all eyes combined. The results were comparable, and further analyses included all eyes (n = 342) except for the "diagnosis" subset. In this subset, the eyes in the "miscellaneous" category were not used because of the heterogeneity ofdiagnoses in that category. All means are reported with standard deviations. Kaplan-Meier estimates were used to assess the probability ofcataract formation or extraction 2 and 5 years after the keratoplasty for each risk factor univariately. Multivariate analysis of the risk factors was done using Cox propor tional hazards general linear models. 14 These survival techniques take into account the length of follow-up.
Results The study group comprised 342 eyes in 148 female and 128 male patients. The mean age at the time of kerato plasty was 39.7 ± 19.4 years. The mean follow-up time from penetrating keratoplasty to last examination was 53.1 ± 38.7 months. The most frequent diagnosis was kera toconus ( 161 eyes; 4 7%), followed by Fuchs dystrophy (45 eyes; 13%), herpes simplex (39 eyes; 11%), scars (32 eyes; 10%), persistent ulcers (23 eyes; 7%), miscellaneous diagnoses (22 eyes; 6%), and stromal dystrophies (20 eyes; 6%). Overall, ten eyes required a second penetrating ker atoplasty and two required a third procedure.
Cataract Formation after Penetrating Keratoplasty Lens changes thought to be visually insignificant or not severe enough to warrant cataract removal at the time of keratoplasty were noted preoperatively in 53 (15%) of the 342 eyes studied. Of the remaining 287 eyes that appeared cataract-free preoperatively (preoperative lens status was not recorded for 2 eyes), lens changes developed post operatively in 64 eyes (22% ). It was, of course, difficult to determine lens changes preoperatively in patients with considerable corneal opacity. To obtain a better estimate of the lens clarity, the coaxially illuminated operating microscope was used
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to visualize fundus details after removal of the corneal button. 15 Age, diagnosis, and preoperative visual acuity were found to be univariate significant risk factors for the de velopment ofcataract after penetrating keratoplasty (Table 1). The mean patient age at the time subsequent cataracts were diagnosed was 56.5 ± 14.5 years. The estimated probability ofa cataract developing within 5 years of pen etrating keratoplasty increased from 23% in the 40- to 49 year-old group to 69% in the 50- to 59-year-old group, and 91% in patients 60 to 69 years of age. The 5-year probability of a cataract developing varied significantly according to diagnosis (e.g., 7% for keratoconus, 74% for Fuchs dystrophy). For a preoperative visual acuity of 20/ 40 or better, there was a 4% chance of cataract formation versus 25% for a preoperative visual acuity of 20/100 to 20/800. Multivariate models yielded age as the only risk factor that remained significant for the formation of cat aracts in these subjects (coefficient= 0.095; standard error = 0.0087; p = 0.0001). In 3% ofeyes that underwent penetrating keratoplasty, posterior subcapsular cataracts developed later. In only 1% ofeyes with keratoconus, postoperative posterior sub capsular cataracts developed, none of which required subsequent cataract extraction.
Cataract Extraction after Penetrating Keratoplasty Cataract extraction was performed in 21% of the 342 eyes after corneal transplantation. Eight percent (6 eyes) ofthe eyes that underwent cataract extraction also had a repeat penetrating keratoplasty due to graft failure before the cataract surgery. The median interval between kerato plasty and cataract extraction was 13 months. The median follow-up time from cataract extraction to final exami nation was 37 months. The mean patient age at the time of penetrating keratoplasty for patients who subsequently had a cataract removed was 62.2 ± 11.8 years, and the mean age at the time of cataract extraction was 64.0 ± 11.4 years. Considered separately (univariate analysis), age, sex, diagnosis, and the presence of preoperative lens opacities were found to be highly significant risk factors for sub sequent cataract extraction (P = 0.0001); preoperative vi sual acuity was also a risk factor, but a less significant one (P = 0.03). Race was not a significant factor. Table 2 shows the estimated probabilities of cataract extraction 2 and 5 years after penetrating keratoplasty for different risk factors. Figures 1 and 2 show the Kaplan-Meier es timates for cataract extraction after penetrating kerato plasty by patient age and diagnosis. Patients younger than 50 years of age had less than a 6% chance of requiring cataract extraction within 5 years of keratoplasty. The post-keratoplasty probability of needing cataract extraction within 5 years increased dra matically to 53% in the 50- to 59-year-old group, and was nearly 100% in patients older than 70 years ofage. Female patients (mean age, 42.1 ± 21.5 years) had an estimated 33% chance of requiring cataract extraction within 5 years
Martin et al · Cataracts after Penetrating Keratoplasty Table 1. Probability of a Cataract Developing 2 and 5 Years after Penetrating Keratoplasty in Preoperatively Cataract-free Patients, and Observed Proportions All Diagnosis* Keratoconus Fuchs dystrophy Herpes simplex keratitis Stromal dystrophies Ulcer Scar Age (yrs) 0-9 10-19 20-29 30-39 40-49 50-59 60-69 70-86 Race White Black Sex Female Male Preoperative visual acuity 20/ 40 or better 20/ 50-80 20/ 100-800 CF, HM, LP CF
No.
2 yrs
5 yrs
287
0.18
0.23
159 21 32 15 16 26
0.06 0.47 0.28 0.27 0.35 0.29
O.Q7 0.74 0.34 0.35 0.35 0.36
13 23 79 71 38 34 19 10
0.00 0.00 0.03 O.Q3 0.19 0.48 0.72 0.90
0.11 0.00 0.03 0.06 0.23 0.69 0.91 0.90
245 42
0.18 0.16
0.23 0.24
149 138
0.22 0.14
0.27 0.19
26 76 121 58
0.04 0.08 0.15 0.35
0.04 0.16 0.25 0.42
= counting fingers; HM = hand motions; LP =
* N = 269; miscellaneous excluded.
p
0.0001
0.0001
0.71 0.08 0.00012
Observed Proportions 0.22 0.06 0.57 0.41 0.33 0.37 0.35 0.08 0 0.04 0.04 0.32 0.62 0.79 0.90 0.19 0.23 0.26 0.18 0.04 0.16 0.23 0.40
light perception.
of penetrating keratoplasty versus 14% for male patients (mean age, 39.1 ± 17.8 years). When lens opacities thought to be visually insignificant were present at the time of penetrating keratoplasty, 64% ofeyes subsequently underwent cataract extraction, versus 14% of those without preoperative lens changes. The cor responding 5-year probabilities of cataract extractions were 86% and 15%. Eyes with a corrected preoperative visual acuity of 20/40 or better had a 4% chance of re quiring subsequent cataract extraction within 5 years, whereas eyes with a visual acuity of 20/100 to 20/800 had a 28% chance. Individual diagnoses varied greatly with respect to the probability of cataract extraction after penetrating keratoplasty. Patients with keratoconus had only a 2% chance within 5 years versus 73% for patients with Fuchs dystrophy. Multivariate analysis was performed on 320 eyes (eyes in the miscellaneous category were not included) with one of the six listed diagnoses. All variables that were significant in univariate analyses remained significant in multivariate analyses, except preoperative visual acuity. Table3 illustrates the Cox model oftime from penetrating
keratoplasty to cataract extraction. The 2- and 5-year probabilities ofcataract removal were calculated for com binations of age and diagnosis (Table 4). For example, the probability of requiring cataract extraction within 5 years of penetrating keratoplasty was 1% for a 30-year old patient with keratoconus, 32% for a 50-year-old patient with herpes simplex scarring, 61 % for a 60-year-old patient with stromal corneal dystrophy, and 67% for a 60-year old patient with Fuchs dystrophy. Corneal rejection episodes occurred in 13 (18%) of the 72 eyes that had undergone a subsequent cataract extraction, and in only 23 (9%) ofthe 270 eyes that had not had a subsequent cataract extraction (P = 0.0191 ). No rejection episodes occurred less than 12 months after cataract extraction. Only four cataracts developed after a rejection episode, and none was noted within 4 months of the rejection episode. There were two cata racts at 4 months, one at 33 months, and one at 80 months. Failed grafts occurred in 15% of patients who under went cataract extraction after penetrating keratoplasty, and in 5% of those who underwent only penetrating ker atoplasty (P = 0.0103).
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Table 2. Kaplan-Me ier Estimates of the Probability of Cataract Extraction 2 and 5 Years after Penetrating Keratoplast y in All Patients, and Observed Proportions All Diagnosis* Keratoconus Fuchs dystrophy Herpes simplex keratitis Stromal dystrophies Ulcer Scar Age (yrs) 0-9 10-19 20-29 30-39 40-49 50-59 60-69 70-86 Race White Black Sex Female Male Preoperative lens opacityt No Yes Preoperative visual acuity 20/40 or better 20/ 50-80 20/ 100-800 CF,HM, LP
No.
2 yrs
5 yrs
342
0.17
0.24
161 45 39 20 23 32
0.02 0.49 0.19 0.31 0.34 0.16
0.02 0.73 0.34 0.39 0.41 0.22
16 25 79 74 39 39 50 20
0.00 0.00 0.03
0.06 0.30 0.54 0.72
0.00 0.00 0.03 0.04 0.06 0.53 0.68 1.00
293 49
0.18 0.15
0.25 0.24
183 159
0.25 0.09
0.33 0.14
287 53
0.10 0.57
0.15 0.86
26 94 142 70
O.Q4 0.17 0.18 0.21
0.04 0.20 0.28 0.33
o.oz
p
0.0001
0.0001
0.44 0.0001 0.0001 0.03
Observed Proportions 0.21 0.02 0.64 0.28 0.35 0.35 0.19 0.00 0.00 0.03 0.03 0.08 0.54 0.60 0.75 0.22 0.16 0.29 0.13 0.14 0.64 0.04 0.19 0.23 0.27
CF = counting fingers; HM = hand motions; LP = light perception. • N = 320; miscellaneous excluded. t Thought not to be visually significant.
Discussion Whether to perform cataract surgery subsequent to pen etrating keratoplasty or as part of a combined procedure has been debated at length for many years. The bulk of the available literature stresses the visual outcomes and postoperative graft clarity of the combined versus the staged procedures. 1- 8 This study provides an insight into the development of cataracts and the incidence of sub sequent cataract extraction in a referred corneal practice. Several indicators that can be used to determine the ap propriate procedure are defined. For clarity, the discussion will be divided into two parts, as in the Results section.
Cataract Formation after Penetrating Keratoplas ty As previously stated, diagnosis, age, and preoperative vi sion were risk factors for the development of cataract (P
116
< 0.0002) when considered separately. However, in the multivariate model, only age remained a significant risk factor for a cataract developing subsequent to corneal transplantation. The mean age at which cataract was first noted after penetrating keratoplasty was 56.5 ± 14.5 years. Our results show a higher prevalence of cataracts after keratoplasty in comparable age groups than in studies of patients not having undergone keratoplasty 16- 22 : 32% ver sus 4%16 in the 40- to 49-year-old age group, and 83% versus 33%, 19 28%, 20•21 and 42% 18 in the 55- to 64-year old age group. Comparisons of this kind are difficult to assess, however, because the definitions of early cataract and lens opacities often are very different among studies. Additionally, the prevalence of inflammation, ocular in jury, and the use of topical medications was greater in our patient population than in some of the other popu lations reported. Posterior subcapsular cataract formation after pene trating keratoplasty has been reported, particularly after
Martin et al
Cataracts after Penetrating Keratoplasty
1.00
1.00
i 50-59
JFuchs'
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keratoplasty for keratoconus. 10- 13 In 3% of the eyes in our series that had penetrating keratoplasty, posterior sub capsular cataract developed. In only I% ofthose eyes with keratoconus, posterior subcapsular cataract developed, and none required cataract extraction. These results are lower than the incidence ofposterior subcapsular cataract noted after penetrating keratoplasty for keratoconus by Donshik et al 11 (31.8%; 21.5% requiring extracapsular cataract extraction) and by Sharif and Casey 13 (12%; 5% required cataract extraction). These posterior subcapsular cataracts have been related to the dosage and duration of topical steroid use. 12 Our typical steroid regimen uses prednisolone acetate 1% four times daily for the first week, the dose being tapered to twice weekly by 4 months after transplantation. Our low incidence of posterior subcap sular cataract formation, as well as our low incidence of rejection episodes, shows that this protocol for the rapid reduction of steroids is both safe and effective.
Cataract Extraction after Penetrating Keratoplasty Cataract extraction was performed in 21% ofall eyes after penetrating keratoplasty. However, 54% ofeyes in the 50 to 59-year-old age group and 75% ofeyes in those patients 70 years of age or older required such extractions. ~he probability of requiring surgery 5 years after penetratmg keratoplasty jumped from 6% in the 40- to 49-year-old age group to 53% in the 50- to 59-year-old age group and to 100% in those patients 70 years of age or older. There fore, the age of the patient at the time of penetrating k~r atoplasty is important in predicting the future necessity of cataract extraction. The mean age at the time of pen etrating keratoplasty for all of our patients was 39.7 ±
I
r-------~
!Scars
I
~~==jFJo~·~•hi: /d.)--'Kera,t~o~co~n~u~s~~~~~~~~~~~
0
20
40
60
80
100 120 140
Months Post Keratoplasty
Months Post Keratoplasty Figure 1. Kaplan-Meier estimates of cataract extraction after penetrating keratoplasty by age.
[Ulcers
r-f
rr'
)Herpes
Figure 2. Kaplan-Meier estimates of cataract extraction after penetrating keratoplasty by diagnosis.
19.4 years, and for those who underwent subsequent cat aract extraction the mean age was 62.2 ± 11.8 years. The mean age at the time of cataract extraction was 64.0 ± 11.4 years. The mean age in a general population of 198 consecutive cataract extractions in the study reported by Adamsons et al 16 was 67.5 years. In another discussion of possible risk factors for cataract formation in a general population, age again was listed first, followed by diabetes, hypertension, nutritional status, and family historyY However, while age was the most important risk factor for lens extraction, multivariate analysis of our patients who underwent cataract extraction after penetrating ker atoplasty indicated four other independent risk factors as well: preoperative visual acuity, sex, diagnosis, and pre operative lens opacities. Therefore, factors other than age are important in determining the overall risk of requiring cataract extraction after penetrating keratoplasty. Table 3. Cox Model for Time to Cataract Extraction from Penetrating Keratoplasty (n = 320) Variable
Coefficient
Standard Error
p
Age Male Fuchs dystrophy Herpes Dystrophies Ulcers Scars Preoperative lens opacity
0.0706 -0.9897 1.8792 2.1627 1.6376 1.6697 1.5896 0.7474
0.0110 0.3054 0.6506 0.6752 0.7198 0.7143 0.7334 0.3017
0.0001 0.0012 0.0039 0.0014 0.0229 0.0194 0.0302 0.0132
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Table 4. Probability of Needing a Cataract Extraction after Penetrating Keratoplasty by Age and Diagnosis, from Cox Model (n = 320) Age (yrs) 2 Yrs Later
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75
5 Yrs Later
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75
Keratoconus
Fuchs Dystrophy
Herpes Simplex Keratitis
Stromal Dystrophies
0.00 0.00 0.00 0.00 0.00 0.01 0.01 0.01 0.02 0.03 0.04 0.06 0.09 0.13 0.19
0.01 0.01 0.02 0.02 0.04 0.05 0.08 0.11 0.16 0.23 0.32 0.43 0.57 0.71 0.84
0.01 0.01 0.01 0.02 0.03 0.04 0.06 0.09 0.13 0.18 0.26 0.35 0.48 0.62 0.76
0.00 0.00 0.00 0.01 0.01 0.01 0.02 0.03 0.04 0.06 0.08 0.12 0.17 0.24 0.34
0.01 0.02 0.03 0.05 0.07 0.10 0.15 0.21 0.29 0.40 0.53 0.67 0.81 0.91 0.97
0.01 0.02 0.02 0.04 0.05 0.08 0.11 0.16 0.23 0.32 0.44 0.57 0.72 0.85 0.94
Women had a significantly higher risk ofrequiring cat aract extractions. The proportional hazards general linear model procedure for patients who underwent cataract ex traction subsequent to penetrating keratoplasty indicated that sex was a risk factor even if age, diagnoses, and pre operative lens opacities were taken into account. However, for cataract formation alone, the sex of the patient was not found to be a risk factor in this study. Two other studies 17 •18 reported a higher prevalence of cataracts in women; one other study 19 reported a greater severity of cataracts in women, but no significant difference in the overall prevalence ofcataracts. The higher risk ofcataract extractions in our study also suggests a greater severity of cataracts in women. As previously stated, patients who were believed to have visually significant lens changes at the time of penetrating keratoplasty underwent a combined procedure, and
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Ulcer
Scar
0.01 0.01 0.01 0.02 0.03 0.04 0.07 0.10 0.14 0.20 0.28 0.38 0.51 0.65 0.79
0.00 0.01 0.01 0.02 0.02 0.03 0.05 0.11 0.15 0.22 0.30 0.41 0.55 0.69
0.00 0.00 0.01 0.01 0.02 0.02 0.03 0.05 O.D7
0.01 0.02
0.01 0.01 0.02 0.03 0.04 0.07 0.09 0.14 0.20 0.28 0.38 0.51 0.65 0.79 0.90
0.01 0.01 0.01 0.02 0.03 0.04 0.06 0.09 0.14 0.19 0.27 0.38 0.50 0.64 0.78
O.D3
0.04 0.06 0.09 0.12 0.18 0.25 0.35 0.47 0.61 0.75 0.87 0.95
O.D7
0.10 0.15 0.21 0.30 0.41 0.54
therefore were excluded from the study. Fifty-three other eyes ( 16%) had early lens changes at the time of pene trating keratoplasty that were not believed to be visually significant, and 64% 9fthose eyes later underwent cataract extraction. The risk of a subsequent cataract extraction was 86% within 5 years for those with preoperative lens opacities as opposed to 15% of those with no preoperative opacity. Diagnosis also affected the risk of subsequent cataract extraction independent of age. As noted above, certain inflammatory conditions are often associated with an in crease in cataract formation. This may be due to the in flammation itself, to increased preoperative and postop erative steroid use, or to both. The probability ofa patient with Fuchs dystrophy having a cataract extraction was 36 times greater than that for a patient with keratoconus (73% versus 2%). Payant et al9 observed that 44% ofthose who
Martin et al · Cataracts after Penetrating Keratoplasty underwent penetrating keratoplasty for Fuchs dystrophy later underwent cataract extraction, a lower incidence than the 64% seen in our study. The mean follow-up times were comparable (57.6 ± 34.8 months in the Payant et al study; 53.1 ± 38.7 months in our study). Corneal graft failure after cataract extraction was noted in 15% of our patients. This compares favorably with the failure rates in other studies of 0% to 40%. 7- 9 •13 As pre viously stated, corneal rejection episodes occurred after cataract extraction in 18% of patients, versus 9% in pa tients who did not undergo cataract extraction. However, cataract extraction was not associated with graft rejection within the first 12 postoperative months in any patient. Ficker et al 2 noted a 12% (3 eyes) rejection rate, and Payant et al 9 noted a 3% (1 eye) rejection rate in the immediate postoperative period.
Conclusion The authors believe that these data provided on cataract formation and cataract extraction after penetrating ker atoplasty will help surgeons determine the appropriate procedure (penetrating keratoplasty alone or combined with cataract extraction) for their patients. This infor mation also can be used to counsel patients on the risks of cataract formation. The tables offer useful information for patients of different ages and diagnoses. Due to the high likelihood of a second procedure being needed, we believe that this study shows that combined surgery is indicated in the older patient who shows even early evi dence of cataract formation, regardless of the diagnosis leading to the need for the keratoplasty. We agree with Binde~ 3 that, although a delayed sec ondary operation may, in some cases, provide patients with refractive errors closer to emmetropia, this advantage is offset by the increased risks to the transplant and the delay in recovery ofbest vision, as well as by the increased costs and risks associated with two separate operations.
References 1. Arentsen JJ, Laibson PR. Penetrating keratoplasty and cat aract extraction. Combined vs nonsimultaneous surgery. Arch Ophthalmol 1978;96:75-6. 2. Ficker LA, Kirkness CM, Steele AD MeG, et al. Intraocular surgery following penetrating keratoplasty: the risks and ad vantages. Eye 1990;4:693-7. 3. Stark WJ, Maumenee AE. Cataract extraction after suc cessful penetrating keratoplasty. Am J Ophthalmoll973;75: 751-4.
4. Crawford GJ, Stulting RD, Waring GO III, et al. The triple procedure: analysis of outcome, refraction, and intraocular lens power calculation. Ophthalmology 1986;93:817-24. 5. Brightbill FS, Stainer GA, Hunkeler JD. A comparison of intracapsular and extracapsular lens extraction combined with keratoplasty. Ophthalmology 1983;90:34-7. 6. Meyer RF, Musch DC. Assessment of success and compli cations of triple procedure surgery. Am J Ophthalmol 1987; 104:233-40. 7. Fine M. Therapeutic keratoplasty and Fuchs' dystrophy. Am J Ophthalmol1964;57:371-8. 8. Brady SE, Rapuano CJ, Arentsen JJ, et al. Clinical indica tions for and procedures associated with penetrating kera toplasty, 1983-1988. Am J Ophthalmol 1989;108:118-22. 9. Payant JA, Gordon LW, VanderZwaag R, Wood TO. Cat aract formation following corneal transplantation in eyes with Fuchs' endothelial dystrophy. Cornea 1990;9:286-9. 10. Gasset AR, Bellows RT. Posterior subcapsular cataracts after topical corticosteroid therapy. Ann Ophthalmol 1974;6: 1263-5. 11. Donshik PC, Cavanaugh HD, BoruchoffSA, Dohlman CH. Posterior subcapsular cataracts induced by topical cortico steroids following keratoplasty for keratoconus. Ann Ophthalmol 1981; 13:29-32. · 12. Wood TO, Waltman SR, Kaufman HE. Steroid cataracts following penetrating keratoplasty. Ann Ophthalmol 1971 ;3: 496-8. 13. Sharif KW, Casey TA. Penetrating keratoplasty for kera toconus: complications and long-term success. Br J Ophthalmol1991;75:142-6. 14. Miller RG Jr. Survival Analysis. New York: Wiley, 1981. 15. Abel R Jr, Binder PS. Intraoperative evaluation of the lens during penetrating keratoplasty. Ann Ophthalmol 1975;7: 1631-5. 16. Adamsons I, Mufioz B, Enger C, Taylor HR. Prevalence of lens opacities in surgical and general populations. Arch Ophthalmol1991;109:993-7. 17. Sperduto RD, Hiller R. The prevalence of nuclear, cortical, and posterior subcapsular lens opacities in a general pop ulation sample. Ophthalmology 1984;91 :815-8. 18. Leibowitz HM, Krueger DE, Maunder LR, et al. The Fra mingham Eye Study Monograph. Surv Ophthalmol 1980;24(Suppl). 19. Klein BEK, Klein R, Linton KLP. Prevalence of age-related lens opacities in a population. The Beaver Dam Eye Study. Ophthalmology 1992;99:546-52. 20. Hiller R, Sperduto RD, Ederer F. Epidemiologic associations with nuclear, cortical and posterior subcapsular cataracts. Am J Epidemiol 1986;124:916-25. 21. Leske MC, Sperduto RD. The epidemiology of senile cat aracts: a review. Am J Epidemiol 1983; 118:152-65. 22. Martinez GS, Campbell AJ, Reinken J, Allan BC. Prevalence of ocular disease in a population study of subjects 65 years old and older. Am J Ophthalmol 1982;94:181-9. 23. Binder PS. Intraocular lens implantation after penetrating keratoplasty. Refractive Corneal Surg 1989;5:224-30.
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Lens opacities are common in older patients requiring penetrating keratoplasty. Whether to perform penetrating keratoplasty alone or in combination with cataract ex traction in the presence of preoperative lens opacities (combined procedure) often is a dilemma for the operating surgeon. Many articles have focused on the relative merits of penetrating keratoplasty with subsequent cataract ex traction versus combined surgery, I-s but little has been published on the incidence of subsequent cataract for mation or of the need for cataract extraction after pene trating keratoplasty. Payant et al 9 reviewed patients with
Fuchs dystrophy and found that cataracts developed in 60% of eyes after penetrating keratoplasty, with 44% re quiring subsequent cataract extraction. Several other au thors have discussed the formation of posterior subcap sular cataracts after penetrating keratoplasty and have re lated them to topical steroid dosage. 10- 13 The objectives ofthis study are to identify the incidence ofand risk factors for ( 1) the formation of cataracts after penetrating kera toplasty, and (2) the need for cataract extraction after ker atoplasty.
Originally received: December 14, 1992. Revision accepted: June 14, 1993. From the Department of Ophthalmology and Department of Public Health Sciences, Bowman Gray School of Medicine of Wake Forest University, Winston-Salem. Presented as a poster at the American Academy of Ophthalmology An nual Meeting, Dallas, November 1992. Reprint requests to John W. Reed, MD, Wake Forest University Eye Center, Medical Center Blvd, Winston-Salem, NC 27157-1033.
Materials and Methods A retrospective review of 1271 eyes that underwent pen etrating keratoplasty consecutively from January 1979 through December 1988 was performed. All penetrating keratoplasties were performed or supervised by one sur geon (JWR). Five hundred eighty-three eyes were phakic before the penetrating keratoplasty; 238 of these phakic
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Volume 101, Number 1, January 1994
eyes had visually significant cataracts and underwent cat aract extraction at the time of penetrating keratoplasty. The remaining 345 phakic eyes (278 patients) (i.e., those that did not undergo cataract extraction at the time of keratoplasty) are the focus of this study. Three eyes (2 patients) had incomplete data, leaving a study group of 342 eyes (276 patients). Diagnosis, age, race, sex, preoperative lens opacities, preoperative visual acuity, and length of follow-up were recorded. Associated and independent ocular diseases and previous operations (e.g., glaucoma, amblyopia, branch retinal vein occlusion, trabeculectomy), postoperative complications (e.g., graft rejection, persistent epithelial defect, large postoperative astigmatism), and procedures done postoperatively (e.g., relaxing incisions, YAG cyclo photocoagulation) also were recorded. Initial statistical analyses were performed on 276 eyes ( 1 eye per patient) as well as on all eyes combined. The results were comparable, and further analyses included all eyes (n = 342) except for the "diagnosis" subset. In this subset, the eyes in the "miscellaneous" category were not used because of the heterogeneity ofdiagnoses in that category. All means are reported with standard deviations. Kaplan-Meier estimates were used to assess the probability ofcataract formation or extraction 2 and 5 years after the keratoplasty for each risk factor univariately. Multivariate analysis of the risk factors was done using Cox propor tional hazards general linear models. 14 These survival techniques take into account the length of follow-up.
Results The study group comprised 342 eyes in 148 female and 128 male patients. The mean age at the time of kerato plasty was 39.7 ± 19.4 years. The mean follow-up time from penetrating keratoplasty to last examination was 53.1 ± 38.7 months. The most frequent diagnosis was kera toconus ( 161 eyes; 4 7%), followed by Fuchs dystrophy (45 eyes; 13%), herpes simplex (39 eyes; 11%), scars (32 eyes; 10%), persistent ulcers (23 eyes; 7%), miscellaneous diagnoses (22 eyes; 6%), and stromal dystrophies (20 eyes; 6%). Overall, ten eyes required a second penetrating ker atoplasty and two required a third procedure.
Cataract Formation after Penetrating Keratoplasty Lens changes thought to be visually insignificant or not severe enough to warrant cataract removal at the time of keratoplasty were noted preoperatively in 53 (15%) of the 342 eyes studied. Of the remaining 287 eyes that appeared cataract-free preoperatively (preoperative lens status was not recorded for 2 eyes), lens changes developed post operatively in 64 eyes (22% ). It was, of course, difficult to determine lens changes preoperatively in patients with considerable corneal opacity. To obtain a better estimate of the lens clarity, the coaxially illuminated operating microscope was used
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to visualize fundus details after removal of the corneal button. 15 Age, diagnosis, and preoperative visual acuity were found to be univariate significant risk factors for the de velopment ofcataract after penetrating keratoplasty (Table 1). The mean patient age at the time subsequent cataracts were diagnosed was 56.5 ± 14.5 years. The estimated probability ofa cataract developing within 5 years of pen etrating keratoplasty increased from 23% in the 40- to 49 year-old group to 69% in the 50- to 59-year-old group, and 91% in patients 60 to 69 years of age. The 5-year probability of a cataract developing varied significantly according to diagnosis (e.g., 7% for keratoconus, 74% for Fuchs dystrophy). For a preoperative visual acuity of 20/ 40 or better, there was a 4% chance of cataract formation versus 25% for a preoperative visual acuity of 20/100 to 20/800. Multivariate models yielded age as the only risk factor that remained significant for the formation of cat aracts in these subjects (coefficient= 0.095; standard error = 0.0087; p = 0.0001). In 3% ofeyes that underwent penetrating keratoplasty, posterior subcapsular cataracts developed later. In only 1% ofeyes with keratoconus, postoperative posterior sub capsular cataracts developed, none of which required subsequent cataract extraction.
Cataract Extraction after Penetrating Keratoplasty Cataract extraction was performed in 21% of the 342 eyes after corneal transplantation. Eight percent (6 eyes) ofthe eyes that underwent cataract extraction also had a repeat penetrating keratoplasty due to graft failure before the cataract surgery. The median interval between kerato plasty and cataract extraction was 13 months. The median follow-up time from cataract extraction to final exami nation was 37 months. The mean patient age at the time of penetrating keratoplasty for patients who subsequently had a cataract removed was 62.2 ± 11.8 years, and the mean age at the time of cataract extraction was 64.0 ± 11.4 years. Considered separately (univariate analysis), age, sex, diagnosis, and the presence of preoperative lens opacities were found to be highly significant risk factors for sub sequent cataract extraction (P = 0.0001); preoperative vi sual acuity was also a risk factor, but a less significant one (P = 0.03). Race was not a significant factor. Table 2 shows the estimated probabilities of cataract extraction 2 and 5 years after penetrating keratoplasty for different risk factors. Figures 1 and 2 show the Kaplan-Meier es timates for cataract extraction after penetrating kerato plasty by patient age and diagnosis. Patients younger than 50 years of age had less than a 6% chance of requiring cataract extraction within 5 years of keratoplasty. The post-keratoplasty probability of needing cataract extraction within 5 years increased dra matically to 53% in the 50- to 59-year-old group, and was nearly 100% in patients older than 70 years ofage. Female patients (mean age, 42.1 ± 21.5 years) had an estimated 33% chance of requiring cataract extraction within 5 years
Martin et al · Cataracts after Penetrating Keratoplasty Table 1. Probability of a Cataract Developing 2 and 5 Years after Penetrating Keratoplasty in Preoperatively Cataract-free Patients, and Observed Proportions All Diagnosis* Keratoconus Fuchs dystrophy Herpes simplex keratitis Stromal dystrophies Ulcer Scar Age (yrs) 0-9 10-19 20-29 30-39 40-49 50-59 60-69 70-86 Race White Black Sex Female Male Preoperative visual acuity 20/ 40 or better 20/ 50-80 20/ 100-800 CF, HM, LP CF
No.
2 yrs
5 yrs
287
0.18
0.23
159 21 32 15 16 26
0.06 0.47 0.28 0.27 0.35 0.29
O.Q7 0.74 0.34 0.35 0.35 0.36
13 23 79 71 38 34 19 10
0.00 0.00 0.03 O.Q3 0.19 0.48 0.72 0.90
0.11 0.00 0.03 0.06 0.23 0.69 0.91 0.90
245 42
0.18 0.16
0.23 0.24
149 138
0.22 0.14
0.27 0.19
26 76 121 58
0.04 0.08 0.15 0.35
0.04 0.16 0.25 0.42
= counting fingers; HM = hand motions; LP =
* N = 269; miscellaneous excluded.
p
0.0001
0.0001
0.71 0.08 0.00012
Observed Proportions 0.22 0.06 0.57 0.41 0.33 0.37 0.35 0.08 0 0.04 0.04 0.32 0.62 0.79 0.90 0.19 0.23 0.26 0.18 0.04 0.16 0.23 0.40
light perception.
of penetrating keratoplasty versus 14% for male patients (mean age, 39.1 ± 17.8 years). When lens opacities thought to be visually insignificant were present at the time of penetrating keratoplasty, 64% ofeyes subsequently underwent cataract extraction, versus 14% of those without preoperative lens changes. The cor responding 5-year probabilities of cataract extractions were 86% and 15%. Eyes with a corrected preoperative visual acuity of 20/40 or better had a 4% chance of re quiring subsequent cataract extraction within 5 years, whereas eyes with a visual acuity of 20/100 to 20/800 had a 28% chance. Individual diagnoses varied greatly with respect to the probability of cataract extraction after penetrating keratoplasty. Patients with keratoconus had only a 2% chance within 5 years versus 73% for patients with Fuchs dystrophy. Multivariate analysis was performed on 320 eyes (eyes in the miscellaneous category were not included) with one of the six listed diagnoses. All variables that were significant in univariate analyses remained significant in multivariate analyses, except preoperative visual acuity. Table3 illustrates the Cox model oftime from penetrating
keratoplasty to cataract extraction. The 2- and 5-year probabilities ofcataract removal were calculated for com binations of age and diagnosis (Table 4). For example, the probability of requiring cataract extraction within 5 years of penetrating keratoplasty was 1% for a 30-year old patient with keratoconus, 32% for a 50-year-old patient with herpes simplex scarring, 61 % for a 60-year-old patient with stromal corneal dystrophy, and 67% for a 60-year old patient with Fuchs dystrophy. Corneal rejection episodes occurred in 13 (18%) of the 72 eyes that had undergone a subsequent cataract extraction, and in only 23 (9%) ofthe 270 eyes that had not had a subsequent cataract extraction (P = 0.0191 ). No rejection episodes occurred less than 12 months after cataract extraction. Only four cataracts developed after a rejection episode, and none was noted within 4 months of the rejection episode. There were two cata racts at 4 months, one at 33 months, and one at 80 months. Failed grafts occurred in 15% of patients who under went cataract extraction after penetrating keratoplasty, and in 5% of those who underwent only penetrating ker atoplasty (P = 0.0103).
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Ophthalmo logy
Volume 101 , Number 1, January 1994
Table 2. Kaplan-Me ier Estimates of the Probability of Cataract Extraction 2 and 5 Years after Penetrating Keratoplast y in All Patients, and Observed Proportions All Diagnosis* Keratoconus Fuchs dystrophy Herpes simplex keratitis Stromal dystrophies Ulcer Scar Age (yrs) 0-9 10-19 20-29 30-39 40-49 50-59 60-69 70-86 Race White Black Sex Female Male Preoperative lens opacityt No Yes Preoperative visual acuity 20/40 or better 20/ 50-80 20/ 100-800 CF,HM, LP
No.
2 yrs
5 yrs
342
0.17
0.24
161 45 39 20 23 32
0.02 0.49 0.19 0.31 0.34 0.16
0.02 0.73 0.34 0.39 0.41 0.22
16 25 79 74 39 39 50 20
0.00 0.00 0.03
0.06 0.30 0.54 0.72
0.00 0.00 0.03 0.04 0.06 0.53 0.68 1.00
293 49
0.18 0.15
0.25 0.24
183 159
0.25 0.09
0.33 0.14
287 53
0.10 0.57
0.15 0.86
26 94 142 70
O.Q4 0.17 0.18 0.21
0.04 0.20 0.28 0.33
o.oz
p
0.0001
0.0001
0.44 0.0001 0.0001 0.03
Observed Proportions 0.21 0.02 0.64 0.28 0.35 0.35 0.19 0.00 0.00 0.03 0.03 0.08 0.54 0.60 0.75 0.22 0.16 0.29 0.13 0.14 0.64 0.04 0.19 0.23 0.27
CF = counting fingers; HM = hand motions; LP = light perception. • N = 320; miscellaneous excluded. t Thought not to be visually significant.
Discussion Whether to perform cataract surgery subsequent to pen etrating keratoplasty or as part of a combined procedure has been debated at length for many years. The bulk of the available literature stresses the visual outcomes and postoperative graft clarity of the combined versus the staged procedures. 1- 8 This study provides an insight into the development of cataracts and the incidence of sub sequent cataract extraction in a referred corneal practice. Several indicators that can be used to determine the ap propriate procedure are defined. For clarity, the discussion will be divided into two parts, as in the Results section.
Cataract Formation after Penetrating Keratoplas ty As previously stated, diagnosis, age, and preoperative vi sion were risk factors for the development of cataract (P
116
< 0.0002) when considered separately. However, in the multivariate model, only age remained a significant risk factor for a cataract developing subsequent to corneal transplantation. The mean age at which cataract was first noted after penetrating keratoplasty was 56.5 ± 14.5 years. Our results show a higher prevalence of cataracts after keratoplasty in comparable age groups than in studies of patients not having undergone keratoplasty 16- 22 : 32% ver sus 4%16 in the 40- to 49-year-old age group, and 83% versus 33%, 19 28%, 20•21 and 42% 18 in the 55- to 64-year old age group. Comparisons of this kind are difficult to assess, however, because the definitions of early cataract and lens opacities often are very different among studies. Additionally, the prevalence of inflammation, ocular in jury, and the use of topical medications was greater in our patient population than in some of the other popu lations reported. Posterior subcapsular cataract formation after pene trating keratoplasty has been reported, particularly after
Martin et al
Cataracts after Penetrating Keratoplasty
1.00
1.00
i 50-59
JFuchs'
'
l_ _ I I
!'
-.g .~
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0.75
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~
.....
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keratoplasty for keratoconus. 10- 13 In 3% of the eyes in our series that had penetrating keratoplasty, posterior sub capsular cataract developed. In only I% ofthose eyes with keratoconus, posterior subcapsular cataract developed, and none required cataract extraction. These results are lower than the incidence ofposterior subcapsular cataract noted after penetrating keratoplasty for keratoconus by Donshik et al 11 (31.8%; 21.5% requiring extracapsular cataract extraction) and by Sharif and Casey 13 (12%; 5% required cataract extraction). These posterior subcapsular cataracts have been related to the dosage and duration of topical steroid use. 12 Our typical steroid regimen uses prednisolone acetate 1% four times daily for the first week, the dose being tapered to twice weekly by 4 months after transplantation. Our low incidence of posterior subcap sular cataract formation, as well as our low incidence of rejection episodes, shows that this protocol for the rapid reduction of steroids is both safe and effective.
Cataract Extraction after Penetrating Keratoplasty Cataract extraction was performed in 21% ofall eyes after penetrating keratoplasty. However, 54% ofeyes in the 50 to 59-year-old age group and 75% ofeyes in those patients 70 years of age or older required such extractions. ~he probability of requiring surgery 5 years after penetratmg keratoplasty jumped from 6% in the 40- to 49-year-old age group to 53% in the 50- to 59-year-old age group and to 100% in those patients 70 years of age or older. There fore, the age of the patient at the time of penetrating k~r atoplasty is important in predicting the future necessity of cataract extraction. The mean age at the time of pen etrating keratoplasty for all of our patients was 39.7 ±
I
r-------~
!Scars
I
~~==jFJo~·~•hi: /d.)--'Kera,t~o~co~n~u~s~~~~~~~~~~~
0
20
40
60
80
100 120 140
Months Post Keratoplasty
Months Post Keratoplasty Figure 1. Kaplan-Meier estimates of cataract extraction after penetrating keratoplasty by age.
[Ulcers
r-f
rr'
)Herpes
Figure 2. Kaplan-Meier estimates of cataract extraction after penetrating keratoplasty by diagnosis.
19.4 years, and for those who underwent subsequent cat aract extraction the mean age was 62.2 ± 11.8 years. The mean age at the time of cataract extraction was 64.0 ± 11.4 years. The mean age in a general population of 198 consecutive cataract extractions in the study reported by Adamsons et al 16 was 67.5 years. In another discussion of possible risk factors for cataract formation in a general population, age again was listed first, followed by diabetes, hypertension, nutritional status, and family historyY However, while age was the most important risk factor for lens extraction, multivariate analysis of our patients who underwent cataract extraction after penetrating ker atoplasty indicated four other independent risk factors as well: preoperative visual acuity, sex, diagnosis, and pre operative lens opacities. Therefore, factors other than age are important in determining the overall risk of requiring cataract extraction after penetrating keratoplasty. Table 3. Cox Model for Time to Cataract Extraction from Penetrating Keratoplasty (n = 320) Variable
Coefficient
Standard Error
p
Age Male Fuchs dystrophy Herpes Dystrophies Ulcers Scars Preoperative lens opacity
0.0706 -0.9897 1.8792 2.1627 1.6376 1.6697 1.5896 0.7474
0.0110 0.3054 0.6506 0.6752 0.7198 0.7143 0.7334 0.3017
0.0001 0.0012 0.0039 0.0014 0.0229 0.0194 0.0302 0.0132
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Ophthalmology
Volume 101, Number 1, january 1994
Table 4. Probability of Needing a Cataract Extraction after Penetrating Keratoplasty by Age and Diagnosis, from Cox Model (n = 320) Age (yrs) 2 Yrs Later
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75
5 Yrs Later
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75
Keratoconus
Fuchs Dystrophy
Herpes Simplex Keratitis
Stromal Dystrophies
0.00 0.00 0.00 0.00 0.00 0.01 0.01 0.01 0.02 0.03 0.04 0.06 0.09 0.13 0.19
0.01 0.01 0.02 0.02 0.04 0.05 0.08 0.11 0.16 0.23 0.32 0.43 0.57 0.71 0.84
0.01 0.01 0.01 0.02 0.03 0.04 0.06 0.09 0.13 0.18 0.26 0.35 0.48 0.62 0.76
0.00 0.00 0.00 0.01 0.01 0.01 0.02 0.03 0.04 0.06 0.08 0.12 0.17 0.24 0.34
0.01 0.02 0.03 0.05 0.07 0.10 0.15 0.21 0.29 0.40 0.53 0.67 0.81 0.91 0.97
0.01 0.02 0.02 0.04 0.05 0.08 0.11 0.16 0.23 0.32 0.44 0.57 0.72 0.85 0.94
Women had a significantly higher risk ofrequiring cat aract extractions. The proportional hazards general linear model procedure for patients who underwent cataract ex traction subsequent to penetrating keratoplasty indicated that sex was a risk factor even if age, diagnoses, and pre operative lens opacities were taken into account. However, for cataract formation alone, the sex of the patient was not found to be a risk factor in this study. Two other studies 17 •18 reported a higher prevalence of cataracts in women; one other study 19 reported a greater severity of cataracts in women, but no significant difference in the overall prevalence ofcataracts. The higher risk ofcataract extractions in our study also suggests a greater severity of cataracts in women. As previously stated, patients who were believed to have visually significant lens changes at the time of penetrating keratoplasty underwent a combined procedure, and
118
Ulcer
Scar
0.01 0.01 0.01 0.02 0.03 0.04 0.07 0.10 0.14 0.20 0.28 0.38 0.51 0.65 0.79
0.00 0.01 0.01 0.02 0.02 0.03 0.05 0.11 0.15 0.22 0.30 0.41 0.55 0.69
0.00 0.00 0.01 0.01 0.02 0.02 0.03 0.05 O.D7
0.01 0.02
0.01 0.01 0.02 0.03 0.04 0.07 0.09 0.14 0.20 0.28 0.38 0.51 0.65 0.79 0.90
0.01 0.01 0.01 0.02 0.03 0.04 0.06 0.09 0.14 0.19 0.27 0.38 0.50 0.64 0.78
O.D3
0.04 0.06 0.09 0.12 0.18 0.25 0.35 0.47 0.61 0.75 0.87 0.95
O.D7
0.10 0.15 0.21 0.30 0.41 0.54
therefore were excluded from the study. Fifty-three other eyes ( 16%) had early lens changes at the time of pene trating keratoplasty that were not believed to be visually significant, and 64% 9fthose eyes later underwent cataract extraction. The risk of a subsequent cataract extraction was 86% within 5 years for those with preoperative lens opacities as opposed to 15% of those with no preoperative opacity. Diagnosis also affected the risk of subsequent cataract extraction independent of age. As noted above, certain inflammatory conditions are often associated with an in crease in cataract formation. This may be due to the in flammation itself, to increased preoperative and postop erative steroid use, or to both. The probability ofa patient with Fuchs dystrophy having a cataract extraction was 36 times greater than that for a patient with keratoconus (73% versus 2%). Payant et al9 observed that 44% ofthose who
Martin et al · Cataracts after Penetrating Keratoplasty underwent penetrating keratoplasty for Fuchs dystrophy later underwent cataract extraction, a lower incidence than the 64% seen in our study. The mean follow-up times were comparable (57.6 ± 34.8 months in the Payant et al study; 53.1 ± 38.7 months in our study). Corneal graft failure after cataract extraction was noted in 15% of our patients. This compares favorably with the failure rates in other studies of 0% to 40%. 7- 9 •13 As pre viously stated, corneal rejection episodes occurred after cataract extraction in 18% of patients, versus 9% in pa tients who did not undergo cataract extraction. However, cataract extraction was not associated with graft rejection within the first 12 postoperative months in any patient. Ficker et al 2 noted a 12% (3 eyes) rejection rate, and Payant et al 9 noted a 3% (1 eye) rejection rate in the immediate postoperative period.
Conclusion The authors believe that these data provided on cataract formation and cataract extraction after penetrating ker atoplasty will help surgeons determine the appropriate procedure (penetrating keratoplasty alone or combined with cataract extraction) for their patients. This infor mation also can be used to counsel patients on the risks of cataract formation. The tables offer useful information for patients of different ages and diagnoses. Due to the high likelihood of a second procedure being needed, we believe that this study shows that combined surgery is indicated in the older patient who shows even early evi dence of cataract formation, regardless of the diagnosis leading to the need for the keratoplasty. We agree with Binde~ 3 that, although a delayed sec ondary operation may, in some cases, provide patients with refractive errors closer to emmetropia, this advantage is offset by the increased risks to the transplant and the delay in recovery ofbest vision, as well as by the increased costs and risks associated with two separate operations.
References 1. Arentsen JJ, Laibson PR. Penetrating keratoplasty and cat aract extraction. Combined vs nonsimultaneous surgery. Arch Ophthalmol 1978;96:75-6. 2. Ficker LA, Kirkness CM, Steele AD MeG, et al. Intraocular surgery following penetrating keratoplasty: the risks and ad vantages. Eye 1990;4:693-7. 3. Stark WJ, Maumenee AE. Cataract extraction after suc cessful penetrating keratoplasty. Am J Ophthalmoll973;75: 751-4.
4. Crawford GJ, Stulting RD, Waring GO III, et al. The triple procedure: analysis of outcome, refraction, and intraocular lens power calculation. Ophthalmology 1986;93:817-24. 5. Brightbill FS, Stainer GA, Hunkeler JD. A comparison of intracapsular and extracapsular lens extraction combined with keratoplasty. Ophthalmology 1983;90:34-7. 6. Meyer RF, Musch DC. Assessment of success and compli cations of triple procedure surgery. Am J Ophthalmol 1987; 104:233-40. 7. Fine M. Therapeutic keratoplasty and Fuchs' dystrophy. Am J Ophthalmol1964;57:371-8. 8. Brady SE, Rapuano CJ, Arentsen JJ, et al. Clinical indica tions for and procedures associated with penetrating kera toplasty, 1983-1988. Am J Ophthalmol 1989;108:118-22. 9. Payant JA, Gordon LW, VanderZwaag R, Wood TO. Cat aract formation following corneal transplantation in eyes with Fuchs' endothelial dystrophy. Cornea 1990;9:286-9. 10. Gasset AR, Bellows RT. Posterior subcapsular cataracts after topical corticosteroid therapy. Ann Ophthalmol 1974;6: 1263-5. 11. Donshik PC, Cavanaugh HD, BoruchoffSA, Dohlman CH. Posterior subcapsular cataracts induced by topical cortico steroids following keratoplasty for keratoconus. Ann Ophthalmol 1981; 13:29-32. · 12. Wood TO, Waltman SR, Kaufman HE. Steroid cataracts following penetrating keratoplasty. Ann Ophthalmol 1971 ;3: 496-8. 13. Sharif KW, Casey TA. Penetrating keratoplasty for kera toconus: complications and long-term success. Br J Ophthalmol1991;75:142-6. 14. Miller RG Jr. Survival Analysis. New York: Wiley, 1981. 15. Abel R Jr, Binder PS. Intraoperative evaluation of the lens during penetrating keratoplasty. Ann Ophthalmol 1975;7: 1631-5. 16. Adamsons I, Mufioz B, Enger C, Taylor HR. Prevalence of lens opacities in surgical and general populations. Arch Ophthalmol1991;109:993-7. 17. Sperduto RD, Hiller R. The prevalence of nuclear, cortical, and posterior subcapsular lens opacities in a general pop ulation sample. Ophthalmology 1984;91 :815-8. 18. Leibowitz HM, Krueger DE, Maunder LR, et al. The Fra mingham Eye Study Monograph. Surv Ophthalmol 1980;24(Suppl). 19. Klein BEK, Klein R, Linton KLP. Prevalence of age-related lens opacities in a population. The Beaver Dam Eye Study. Ophthalmology 1992;99:546-52. 20. Hiller R, Sperduto RD, Ederer F. Epidemiologic associations with nuclear, cortical and posterior subcapsular cataracts. Am J Epidemiol 1986;124:916-25. 21. Leske MC, Sperduto RD. The epidemiology of senile cat aracts: a review. Am J Epidemiol 1983; 118:152-65. 22. Martinez GS, Campbell AJ, Reinken J, Allan BC. Prevalence of ocular disease in a population study of subjects 65 years old and older. Am J Ophthalmol 1982;94:181-9. 23. Binder PS. Intraocular lens implantation after penetrating keratoplasty. Refractive Corneal Surg 1989;5:224-30.
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