Visual Function and Potential Neurodevelopmental Ocular Markers in ADHD: A Systematic Review and Meta-Analysis

Attention-deficit/hyperactivity disorder (ADHD) has been associated with ocular and visual abnormalities, although findings across studies remain inconsistent. This systematic review and meta-analysis aimed to quantify differences in structural and functional ocular parameters between individuals with ADHD and healthy controls.

PubMed, Web of Science, and Scopus were searched for cross-sectional and cohort studies evaluating ocular or visual parameters in children, adolescents, or adults with ADHD. The review was conducted in accordance with PRISMA guidance, informed by AMSTAR 2 methodological standards, and registered in PROSPERO (CRD420251090876). Eligible outcomes included visual acuity, refraction, ocular biometry, retinal structure, accommodative and binocular function, contrast sensitivity, color perception, and pupillary measures. Pooled mean differences (MDs) or standardized mean differences (SMDs) with 95% confidence intervals (CIs) were calculated using fixed- or random-effects models, as appropriate.

Twenty-seven studies including 888 participants with ADHD and 1,172 controls were included, of which 21 contributed to the quantitative synthesis. No significant between-group differences were found in visual acuity (MD = 0.01; 95% CI [-0.02, 0.03]), cycloplegic spherical equivalent (MD = -0.11 D; 95% CI [-0.32, 0.11]), axial length (MD = 0.50 mm; 95% CI [-0.61, 1.62]), macular thickness (MD = -2.57 μm; 95% CI [-6.49, 1.34]), color perception, or pupil diameter (MD = -0.23 mm; 95% CI [-0.76, 0.31]). Keratometry values were slightly lower in participants with ADHD (MD = -0.37 D; 95% CI [-0.62, -0.12]), and amplitude of accommodation was slightly higher (MD = 0.34 D; 95% CI [0.09, 0.59]). Contrast sensitivity was lower in participants with ADHD at 1.5, 3, 12, and 18 cycles per degree, although these analyses were based on only two studies each and showed substantial heterogeneity at several spatial frequencies. RNFL thickness did not differ significantly in the primary analysis (MD = -2.42 μm; 95% CI [-5.48, 0.64]); however, a sensitivity analysis excluding one influential study showed modest thinning in the ADHD group (MD = -3.69 μm; 95% CI [-5.96, -1.42]). The certainty of evidence was very low across the assessed outcomes.

Current evidence does not indicate consistent or clinically meaningful differences in ocular anatomy, refraction, or most binocular and accommodative measures in individuals with ADHD. Some small group-level differences were observed in contrast sensitivity, keratometry, amplitude of accommodation, and RNFL thickness in sensitivity analysis, but their clinical significance remains uncertain. These findings should be considered exploratory because of the observational study designs, methodological heterogeneity, and very low certainty of evidence.