The Effects of Caffeine Intake on AC/A Ratio, Near Point of Convergence, and Reading Speed

Abstract

Background and Objectives: Accommodation refers to an increase in the convexity of the crystalline lens allowing the eye to change its focus from distance to near objects. It is measured in Diopters. Accommodation can sometimes be excessive, causing the eye to exert more power than needed, which can result in symptoms like eye strain, blurred vision, and headaches. In this study, the effects of caffeine intake on the AC/A ratio, Near Point of Convergence (NPC), and reading speed are evaluated. Caffeine (1,3,7-trimethylxanthine) is the most widely consumed psychoactive stimulant worldwide, commonly found in coffee, tea, energy drinks, carbonated beverages, gums, and cocoa. Its physiological effects are well-documented, including pupil dilation, increased intraocular pressure (IOP), and enhanced accommodation.

METHODOLOGY: A descriptive cross-sectional study was conducted at The University of Faisalabad (TUF) using a convenient sampling technique. The study included 80 emmetropic female, caffeine consumers and aged 18–26 years. Data collection took place between September 2021 and May 2022. The AC/A ratio, NPC, and reading speed were initially assessed in a caffeine-free state. Subsequently, each participant consumed 100 mg of Nestlé black coffee, and these parameters were measured again at intervals of 30, 60, and 90 minutes post-caffeine intake. The AC/A ratio and NPC were quantified by the heterophoric method and the RAF ruler respectively, whereas reading speed was assessed with N10 print. Data analysis was carried out with repeated measures analysis of variance using SPSS version 20.
RESULTS: Among postmenopausal female patients with type 1 osteoporosis, the incidence of sarcopenia was relatively high (90.35%), affecting quality of life in 39.82% of patients, postural instability in 92.21% of patients, and balance in 39.92% of patients.
CONCLUSION: It is concluded that excessive Caffeine consumption has adverse effect on near vision and reading speed. Moreover, it also decreased the amount of AC/A ratio.