Structural and Function Correlation of Cone Packing Utilizing Adaptive Optics and Microperimetry

AIM To assess the functional aspects of cone mosaic and correlate cone packing with retinal sensitivity utilizing microperimetry in emmetropes at different eccentricities. METHODS Twenty-four healthy volunteers underwent microperimetry (MAIA Centervue, Italy) and assessment of photoreceptors using adaptive optics retinal camera, rtx1 (Imagine Eyes, Orsay, France), at 2 and 3 degrees from the foveal centre in 4 quadrants: superior, inferior, temporal, and nasal. Data was analyzed using SPSS version 17 (IBM). Spearman's correlation tests were used to establish correlation between mean cone packing density and retinal sensitivity at different quadrants. RESULTS Thirteen females and 11 males (age range 20-40 years) were included. The cone density was found to be significantly different among all quadrants (temporal = 25786.68/mm(2) ± 4367.07/mm(2), superior = 23009.35/mm(2) ± 5415.81/mm(2), nasal = 22838.09/mm(2) ± 4166.22/mm(2), and inferior = 21097.53/mm(2) ± 4235.84/mm(2)). A statistical significance (P < 0.008) was found between orthogonal meridians, that is, temporal, nasal (48624.77/mm(2))> superior, inferior (44106.88/mm(2)). A drop in retinal sensitivity was observed as the eccentricity increased (P < 0.05). It was also found that as cone packing density decreased retinal sensitivity also decreased (P < 0.05) in all quadrants. This was observed at both 2 and 3 degrees. CONCLUSION It is of crucial importance to establish normative variations in cone structure-function correlation. This may help in detection of subtle pathology and its early intervention.