Multifocal–ERG Assessment of the Influence of Short–Term Supplementation With Carotenoids and Antioxidants on Macular Function in Age–Related Maculopathy

Abstract

Purpose: : To evaluate the influence of short–term antioxidant supplementation on retinal function in age–related maculopathy (ARM) by recording multifocal–electroretinograms (mERGs).

Methods: : Twenty–six patients with ARM and visual acuity ≥ 0.3 LogMAR were enrolled and randomly divided into two groups, similar for age and disease severity: 15 ARM patients had oral supplementation of Vitamin C (180 mg), Vitamin E (30 mg), Zinc (22.5 mg), Copper (1 mg), Lutein (10 mg), Zeaxanthin (1 mg) and Astaxanthin (4 mg) (AZYR SIFI^®, Sifi, Italy) daily for 6 months (T–ARM group, 15 eyes); 11 ARM patients had no dietary supplementation during the same period (NT–ARM group, 11 eyes). They were compared to 15 age–matched controls. MERGs were assessed in control and ARM eyes in response to 61 M–stimuli presented to the central 20 degrees of the visual field, in pre–treatment (baseline) conditions and, in ARM eyes, after 6 months. Ring analysis was performed every five retinal eccentricity areas between the fovea and mid–periphery: 0–2.5 (R1), 2.5–5 (R2), 5–10 (R3), 10–15 (R4) and 15–20 (R5) degrees. mERG response amplitude densities (RAD, nV/deg²) of the N1–P1 component of first order binary kernels were measured in R1–R5.

Results: : In baseline conditions, N1–P1 RADs of R1 observed in T–ARM and NT–ARM eyes were significantly reduced (ANOVA p<0.01) with respect to controls. N1–P1 RADs of R2–R5 observed in T–ARM and NT–ARM were not significantly different (p>0.01) when compared to controls. No differences (p>0.01) in N1–P1 RADs of R1–R5 were observed between T–ARM and NT–ARM eyes. After 6 months of treatment, T–ARM eyes showed a significant increase in N1–P1 RADs of R1 (p<0.01), while no significant (p>0.01) changes were observed in N1–P1 RADs of R2–R5. No significant (p>0.01) changes were found in N1–P1 RADs of R1–R5, in NT–ARM eyes.

Conclusions: : Our results suggest that a selective dysfunction occurs in the central retina (0–2.5 degrees) of ARM eyes. Antioxidant treatment may induce a selective improvement of the central retinal function, whereas no functional changes are present in the other retinal areas. Our data suggest that a potential functional improvement of macular photoreceptors and off bipolar cells¹ could be obtained in patients with ARM after treatment with carotenoids and antioxidants.

References: : ¹Hood, Prog Ret Res 2000, 19: 607–646

Keywords: electroretinography: clinical • antioxidants • photoreceptors: visual performance