Comments on retinal sensitivity over hard exudates in diabetic retinopathy

455 Dear Editor, We read with interest the article “Retinal Sensitivity over Hard Exudates in Diabetic Retinopathy” by Raman et al.[1] The authors analyzed 12 eyes with diabetic retinopathy with hard exudates using microperimetry. They found reduced retinal sensitivity in the areas of hard exudates which correlated negatively with retinal thickness, but not with the size of exudation. We would like to highlight a few important points. Correlating the size of hard exudates to retinal sensitivity is prone to error as baseline retinal sensitivity will also vary depending on the proximity of the area being examined to the foveola.[2] Therefore, positive results may have been masked and it is necessary for the location as well as the size to be taken into account. We suggest analyzing this data based on perifoveal rings, for instance only 2 to 5 degree rings around the fovea. Reduced retinal sensitivity can be due to both retinal thickness and hard exudates. The authors also record a negative relation between retinal sensitivity and retinal thickness in the area of hard exudates. So it is important to know the retinal thickness in the retinal area taken as control. As retinal thickness in the area of hard exudates ranged from 251 to 609 microns, we suggest creating a subgroup for retinal thickness below 300 ‐ 350 microns, nearly normal retinal thickness for the extra foveal for the modality used in the study,[3] and comparing it with the rest of the data. This question is important because one often encounters patients in whom macular edema resolves with persistent hard exudates without any visual gain.