Prophylactic laser peripheral iridotomy and cataract progression.
OBJECTIVE
To determine whether prophylactic laser peripheral iridotomy (LPI) for primary angle closure (PAC) is associated with cataract progression.


METHODS
In 1999, Mongolian volunteers aged>or=50 years were invited to participate in a longitudinal study. Glaucoma was excluded in all participants and 712 of them were selected to undergo a full ophthalmic examination as part of the study protocol. Lenses were graded and PAC diagnosed using international classification systems. In 2005, all traced participants underwent a similar dilated examination. Diagnosis of cataract progression was based on the inter-observer variation +2 standard deviations. The association between LPI at baseline and cataract progression was assessed using chi2-test and logistic regression.


RESULTS
Of 712 participants, 158 were diagnosed with occludable angles and treated with LPI. In 2005, 137 participants (19.2%) had died, 315 (315/575=54.8%) were traced, and dilated examination was performed on 276 (48%) of them. Progression of nuclear opacity (NO), cortical, and posterior subcapsular (PSC) opacities were evident in 40 (14.5%, 95% confidence interval (CI)=10.6-19.2%), 89 (32.2%, 95% CI=26.8-38.1%), and 11 participants (4.0%, 95% CI=2.0-7.0%), respectively. Although NO was more likely to progress in those with LPI in a crude analysis (odds ratio (OR)=2.02, 95% CI=1.00-4.11, P=0.05), no evidence of an independent association was detected in multivariate analysis adjusting for age, sex, and baseline Schaffer grading (adjusted OR=1.24, 0.41-3.75, P=0.7). There was no evidence of an association between LPI and progression of PSC or cortical opacities.


CONCLUSIONS
There is no evidence that prophylactic LPI is independently associated with cataract progression in this study.
International Centre for Eye Health, London School of Hygiene and Tropical Medicine, London, UK. jlyy2@medschl.cam.ac.uk
J L Y
JL
Yip
W P
WP
Nolan
C E
CE
Gilbert
D
D
Uranchimeg
J
J
Baassanhuu
P S
PS
Lee
P T
PT
Khaw
G J
GJ
Johnson
P J
PJ
Foster
D000368:Aged; D000369:Aged, 80 and over; D002386:Cataract / Q000145:classification / Q000209:etiology* / Q000503:physiopathology; D018450:Disease Progression; D005260:Female; D015812:Glaucoma, Angle-Closure / Q000150:complications / Q000601:surgery*; D006801:Humans; D032801:Iridectomy / Q000009:adverse effects* / Q000379:methods; D053685:Laser Therapy; D007908:Lens, Crystalline / Q000473:pathology; D016015:Logistic Models; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D008986:Mongolia; D012307:Risk Factors