Abstract
Purpose :
Caffeine and its derivatives (e.g., 7-methylxanthine) are increasingly studied as potential treatments for myopia control. In this study, we assessed the acute effect of caffeine intake on the retinal responses as measured with a global flash mfERG protocol (gmfERG).
Methods :
Young adult subjects (N=24, Age 24.6±2.4 years old, mean±1SD) participated in a randomized two-visit cross-sectional study. After a screening to rule out ocular or systemic conditions that may affect vision, subjects completed a questionnaire to assess habitual caffeine intake. Following measures of weight, refractive error (open-field autorefractor followed by subjective refraction) and optical biometry, including axial length (AXL), subjects were given a capsule with either 300 mg of caffeine anhydrous or a placebo using a double-blind randomized protocol. Subjects were dilated (0.5% tropicamide) 20 minutes prior to ERG testing. Retinal responses were recorded 90 minutes after the consumption of the capsules using a standard gmfERG protocol at three contrast levels (95%, 50% and 30%) with a Veris system (EDI). The amplitudes and latencies of the direct and indirect components (DC, IC, respectively) were extracted for 4 different eccentricities [0-5 (Ring1), 5-10 (Ring2), 10-15 (Ring3) and 15-20 (Ring4) degrees]. Data were analyzed with four within-subject ANCOVAs for amplitude and latency of DC and IC. The within-subject factors were: contrast, caffeine intake (caffeine or placebo), and eccentricity. AXL, refractive error, habitual caffeine intake and weight were considered as continuous covariates.
Results :
Significantly higher IC amplitudes were found after ingestion of caffeine compared to placebo (t = 2.17, corrected p = 0.043, d = 0.44), specifically for the 95% and 50% contrast conditions at Ring3 and Ring4. Caffeine had no effect on DC amplitude or DC and IC latency. The covariates AXL, refractive error, habitual caffeine intake and weight did not have an effect on the results (p-values > 0.320).
Conclusions :
Oral administration of caffeine has an effect on the inner retinal responses as measured by the IC of gmfERG. The effect is only present in the peripheral retina, beyond 10 degrees eccentricity. These results may have implications for understanding the etiology and management of myopia.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.