Introduction: in a country with continental dimensions, the frequencies and the classes of glaucoma are different, according to genetic and cultural background and to the access to medical care. It is necessary to know some parameters (important for the diagnosis of the disease) in each genetic group and in each region, before the introduction of preventive programs.
Objective: to know the distribution of the cup/disc ratio among Brazilian indigenous (Yanomani), from the north region of the country (near Equator line).
Methods: 765 eyes (385 people) were examined by direct ophthalmoscopy. In order to avoid bias, all the observations were performed by the same ophthalmologist. The values were explained in decimal fraction.
Results: The cup/disc ratios ranged form 0.1 to 0.9 (median = 0.2; mean value = 0.28; standard deviation = 0.13; standard error = 0.0048; percentile 25 = 0.2; percentile 75 = 0.3; percentile 95 = 0.6).
Comments: The evaluation of the cup/disc ratio is recommended as the first test in glaucoma surveys. It was suggested that it is necessary to refer, for other examinations, patients with cup/disc ratio >0.5 and or differences ≥ 0.2 between the eyes, and the first degree relative of glaucomatous patients. For the population evaluated in this research, we suggest the referral of all the people with cup/disc ratio ≥ 0.4.