Antioxidants in prevention of cataracts in South India: methodology and baseline data*.
OBJECTIVE
To describe the methodology and baseline data for the Antioxidants in Prevention of Cataracts (APC) study in South India.


METHODS
The APC study is a prospective, 5-year, randomized, triple-masked, placebo-controlled, field-based clinical trial to examine the effect of antioxidants (combination tablet of vitamins A, C, and E) on progression of cataract. The primary outcome variable is cataract progression (nuclear opalescence), evaluated with the slit-lamp biomicroscope by the Lens Opacification Classification System III method. Secondary outcome variables are progression in cortical and posterior subcapsular opacity and nuclear color, change in best corrected visual acuity, myopic shift, and treatment failure (progression to cataract surgery or best corrected vision worse than 20/400 in an eye). Inclusion criteria are age between 35 and 50 years and best-corrected visual acuity of 20/40 or better. Exclusion criteria are a diagnosis of diabetes mellitus or nonfasting blood glucose level>7.8 mmol/L, history or presence of various ocular conditions or treatment forms, or current use of vitamin supplements. Baseline ophthalmic, demographic, and potential cataract risk factor data (such as smoking, sunlight, or alcohol exposure) were compared between groups on an intent-to-treat basis.


RESULTS
Of 954 people screened, 798 were enrolled, a sample size which exceeded the required estimate. More than 80% of subjects had 20/20 or better vision in at least one eye, and baseline prevalence of significant cataract according to the LOCS III grading scale was high. The two treatment groups were comparable for all baseline measures except alcohol intake.


CONCLUSIONS
The sample size and group baseline characteristics will provide sufficient power to detect a change in cataract progression within 5 years.
Department of Ophthalmology, Beckman Vision Center, University of California, San Francisco, CA, USA. david.c.gritz@kp.org
David C
DC
Gritz
Muthiah
M
Srinivasan
Scott D
SD
Smith
Usha
U
Kim
Thomas M
TM
Lietman
John H
JH
Wilkins
Brinda
B
Priyadharshini
Srinivasan
S
Aravind
N Venkatesh
NV
Prajna
Gilbert
G
Smolin
Ravilla Duraisami
RD
Thulasiraj
Sivasubramaniam
S
Selvaraj
John P
JP
Whitcher
D000328:Adult; D000975:Antioxidants / Q000627:therapeutic use*; D002386:Cataract / Q000453:epidemiology / Q000517:prevention & control*; D015340:Epidemiologic Research Design; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007194:India / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011446:Prospective Studies; D016896:Treatment Outcome; D014792:Visual Acuity
D000975:Antioxidants