Visual function deficits in moderately-severe to severe non-proliferative diabetic retinopathy (NPDR) despite normal BCVA

Abstract

Purpose : Advanced diabetic retinal disease(DRD) leads to significant vision loss despite existing treatments addressing complications like proliferative diabetic retinopathy(DR) or diabetic macular edema(DME). Impaired retinal function also affects earlier DRD stages. We evaluated visual function in patients with moderately-severe to severe NPDR and normal Best Corrected Visual Acuity(BCVA).

Methods : Baseline data from treatment naïve DR patients (n=94) from the phase 2 CANBERRA trial (NCT04265261) were analysed. Eligible study eyes had DR Severity Scales (DRSS) of 47 or 53 and a minimal BCVA of 70 letters or 75 letters (with DME). Besides BCVA, Low Luminance Visual Acuity (LLVA), Pelli Robson (PR) contrast vision, quantitative contrast sensitivity function (qCSF), central (30-2) and peripheral (modified 60-4) visual fields by standard automated perimetry were assessed. LLQ and NEI-VFQ-25 were used to assess patient related outcomes. Proportions of patients below a 5% low performing threshold of a theoretical distribution of an age-adjusted healthy population were calculated. Observed medians in Canberra were compared with reported control medians by Wilcoxon’s sum rank test.

Results : Patients with DRSS 47/53 showed following median(min,max) visual function values: BCVA= 84(69,96) letters, n=93; LLVA= 69(40,85) letters, n=85; PR= 32(12,42) letters, n=87; monocular qCSF= 1.09(0.38,1.58), n=85; binocular qCSF= 1.31(0.46,1.79), n=77. Central and peripheral perimetry revealed a median mean deviation (MD,central)= -2.82(-9.43,1.38), n=38, and MD(peripheral)= -3.28(-20.94,0.57), n=36, accompanied by a median number of affected points of 26(3,65), n=35, in central and 19(1,44), n=35, in peripheral visual fields. All functional measures, except BCVA, were significantly different vs normal. Analysis of dichotomized data based on one-sided normal reference limits suggested that 68% NPDR patients show at least one functional deficit below these limits. NEI-VFQ25 and LLQ scores median(Min,Max) were 90.11 (11.33,100), n=61 and 91.67 (22.57,100) n=61, i.e. not different from controls.

Conclusions : Two thirds of NPDR patients with DRSS 47/53 show at least one functional deficit and often have abnormal visual fields indicating widespread, heterogeneous visual function deficits in these DRD stages despite normal BCVA. Further work is needed to assess the relevance of these findings for patients.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.