Correlation between different retinal layers with visual acuity in diabetic retinopathy patients with clinically significant macular edema

Purpose: To study the corelation between outer retinal layer thickness (ORL), outer photoreceptor segment thickness (PROS), and central macular thickness (CMT) with best-corrected visual acuity (BCVA) in patients having clinically significant macular edema (CSME) and compare these parameters with normal patients. Methods: This was a prospective, nonrandomized, observational, comparative study done during the period of January to May 2019. The study included 60 eyes of 36 patients. The patient population was segregated into two Groups: Group I (30 normal eyes of 15 normal patients) and Group II (30 eyes of 21 diabetic patients) with CSME. The comparison between ORL, PROS, and CMT was made between both the groups, and the correlation between ORL thickness, PROS thickness, and CMT with BCVA in Group II was studied. Results: The mean age in Group I was 52.6+10.66 years, and 53.42+8.15 years in Group II. The male/female ratio was 1.1:1 in Group I and 4:3 in Group II. The mean CMT was greater in Group II (330.13 +/- 37.01) than in Group I (222.20 +/- 12.30). The mean ORL thickness was greater in Group I (97.73 +/- 6.92) than in Group II (80.63 +/- 9.03). The PROS thickness was statistically significant in Group I (35.05 +/- 3.4) than in Group II (28.57 +/- 3.53). There was a strong correlation between BCVA and ORL thickness (r = -0.580, P < 0.001) and more strong correlation between BCVA and PROS thickness in Group II (r = -0.611, P < 0.000). There was a moderate correlation between BCVA and CMT (r = 0.410, P < 0.025), and all results were statistically significant. Conclusion: Both ORL and PROS thickness were greater in healthy normal eyes than in eyes with CSME. BCVA was strongly correlated with PROS and ORL thickness and moderately associated with CMT.