The Advanced Glaucoma Intervention Study: 8. Risk of cataract formation after trabeculectomy.
OBJECTIVE
To compare the risk of cataract formation in eyes with and without prior trabeculectomy and to assess other risk factors for cataract.


METHODS
The Advanced Glaucoma Intervention Study (AGIS) has been following 789 eyes in 591 patients with medically uncontrolled open-angle glaucoma. From 1988 to 1992, these eyes were randomly assigned to either an argon laser trabeculoplasty (ALT)-trabeculectomy-trabeculectomy treatment sequence or a trabeculectomy-ALT-trabeculectomy sequence. Cox regression analyses were used to assess risk factors for cataract formation during 7 to 11 years of follow-up.


METHODS
Cataract, defined as either having had cataract surgery or confirmed severe lens opacity with a best-corrected Early Treatment Diabetic Retinopathy Study visual acuity score less than 65 letters (worse than 20/50).


RESULTS
Data are presented on the expected 5-year cumulative probability of cataract formation in each randomized sequence by age and presence of diabetes at study entry. Overall, approximately half of the eyes studied developed cataract. A first trabeculectomy, whether as the first or second AGIS intervention, increased the overall risk of cataract by 78% (risk ratio [RR] = 1.78; P<.001). Diabetes (RR = 1.47; P =.004) and age at study entry (RR = 1.07 per year of age; P<.001) were also risk factors for cataract. When postoperative complications of trabeculectomy were included in the analysis, the increased risk of cataract for eyes with a first trabeculectomy reduced to 47% when complications did not occur (RR = 1.47; P =.003) and increased to 104% when complications did occur (RR = 2.04; P<.001). Several specific postoperative complications of trabeculectomy were associated with increased risk of cataract, particularly marked inflammation (RR = 3.29; P<.001) and flat anterior chamber (RR = 1.80; P =.004). Trabeculectomy with complications was also significantly associated with an increased risk of cataract in each of 3 lens regions: nuclear, cortical, and posterior subcapsular.


CONCLUSIONS
In eyes of AGIS patients, after adjustment for age and diabetes, trabeculectomy increased the risk of cataract formation by 78%.
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002386:Cataract / Q000209:etiology*; D005260:Female; D005500:Follow-Up Studies; D005902:Glaucoma, Open-Angle / Q000601:surgery*; D006801:Humans; D053685:Laser Therapy; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications; D011336:Probability; D012044:Regression Analysis; D012307:Risk Factors; D014130:Trabeculectomy / Q000009:adverse effects*; D014792:Visual Acuity