GSTM1 and anemia (phenotype): Stata v14.0 (Stata Corps Inc.)was used to find the relationship between RNFL thinning and “the dependent factors.” Initially, each eye was separately assigned a value (0, 1, and 2) as per the severity of thinning, and then, the sum of the scores of both eyes was considered as a separate variable, and a multiple linear regression analysis was performed with the independent variables being age, sex, Hb level, years of transfusion, and type of anaemia.