From: The Nakuru eye disease cohort study: methodology & rationale
Disease | Incidence | Progression | ||
---|---|---|---|---|
Definition | At risk | Cases | At risk | Cases |
Blindness and Visual Impairment (VI) | Blind: Persons with VA of ≥3/60 in the better eye at baseline. | Persons who have VA of <3/60 in the better eye at follow up who had ≥3/60 in the better eye at baseline | Categorical changes in visual acuity between: Normal; Mild VI; Moderate VI; Severe VI; Blind, with a minimum of two line Snellen equivalent change in VA. | |
Cataract | Persons without evidence of cataract at baseline based on WHO simplified cataract grading systems | Persons with evidence of cataract at follow-up based on WHO simplified cataract grading systems [45] who did not have evidence at baseline | Persons with evidence of any grade of cataract at baseline based on WHO simplified cataract grading systems | Persons who increase by two or more severity grades in each sub-type of cataract. |
Primary open angle glaucoma | Persons without glaucoma in either eye at baseline based on ISGEO [46] criteria | Persons who develop ISGEO classification 1, 2 or 3 glaucoma by the 6-year follow-up point | Glaucoma or glaucoma suspect case at baseline | Definite, disc or field progression. See below* [47] |
Age-related macula degeneration | Persons who did not have any evidence of AMD at baseline in both eyes | Persons with evidence of early, late or specific AMD lesions | AREDS [48] step 9 or less (no AMD or early AMD) at baseline. | 2-or-more-step increase in combined AREDS score from baseline in persons with gradable fundus photographs at both time points. |
Diabetic retinopathy | Persons with diabetes and free of retinopathy at baseline and persons developing DM by follow up. | Persons with signs of DR (ETDRS) [49] | Persons with diabetes and minimal or moderate DR at baseline | (1) Persons who develop severe DR by the 6-year follow-up |
CSME and incidence of proliferative or severe DRϒ | ||||
(2) Increase by ≥ 3 steps on the ETDRS Severity Scale or development of proliferative DR necessitating photocoagulation therapy or vitrectomy |