Longitudinal analysis of morphological and functional changes in intermediate age-related macular degeneration

Abstract

Purpose: Longitudinal analysis of retinal thickness changes of mesopic as well as scotopic retinal function in patients with iAMD.<br /> Methods: Fifty-nine eyes of 54 AMD patients with large drusen (>125 µm) underwent annual mesopic and scotopic FCP testing and SD-OCT scans over a 3-year time frame. 27 eyes of age-matched healthy control participants were only examined at baseline. Structural analysis assessed the thickness of each retinal layer, particularly the outer retinal layer.<br /> Results: The average PWS decrease for baseline in iAMD patients was -1.67 dB [95% confidence interval: -2.22; -1.12] for mesopic and -2.34 dB [-2.85; -1.84] for scotopic testing, respectively. During 3 years of follow-up time, the sensitivity deviation in patients was decreased by -0.35 dB/year [-0.43; -0.28] under mesopic and increased by +0.20 dB/year [0.12; 0.29] under scotopic testing, respectively (p<0.001). At baseline, the mean relative thickness of ONL was significantly reduced by -0.49 SD [-0.70; -0.28] in eyes with iAMD compared to normal eyes, while the mean localized thickness of RPEDC was significantly increased by +3.22 SD [2.27; 4.17]. Over time, the further variation of RPEDC thickness was +0.51 SD/year, -0.03 SD/year for ONL, and -0.34 SD/year for the inner and outer photoreceptor segments, respectively (p<0.001). Furthermore, structure-function analysis revealed that the change of ONL and RPEDC thickness was associated with both mesopic and scotopic FCP sensitivity (p<0.001). Follow-up time displayed an independent effect on retinal sensitivity, respectively (p<0.001).<br /> Conclusion: Longitudinal FCP sensitivity changes in mesopic retinal function were associated with progressive quantifiable degeneration of the outer retina in iAMD, suggesting that these structure-function parameters may serve as surrogate markers in future clinical trials examining the early stages of AMD.