Ocular dominance and its association with retinal thickness profile – A cross-sectional study

Purpose: The retinal thickness profile is essential for detecting ocular diseases like glaucoma and other optic neuropathies. The retinal nerve fiber layer (RNFL) thickness is affected by age, ethnicity, axial length, optic disc area, and inter-eye differences. Ocular dominance has a strong functional correlation with cerebral cortical activity. However, its relationship with RNFL thickness profile is yet to be fully established. Methods: A cross-sectional study was conducted in 136 healthy adults to study the association between ocular dominance and RNFL parameters measured by Spectral domain optical coherence tomography (SD-OCT) and to study the association of ocular dominance with other parameters such as handedness, intraocular pressure, average axial length, average keratometry, and refractive error. Sighting ocular dominance was detected using the Miles test, and sensory ocular dominance was detected using the fogging test. Visual acuity and refraction assessment were done, and the patients underwent ocular biometry using the Lenstar 900 machine to measure the axial length and keratometry. The RNFL thickness was measured using the Cirrus HD optical coherence tomographer. Results: One hundred and thirty-two (97.06%) individuals were right-handed, four (2.94%) were left-handed, 108 (79.41%) participants were right eye dominant, and 28 (20.59%) were left eye dominant. There was 100% agreement between sighting and sensory ocular dominance. The average RNFL thickness and other measured ocular parameters were comparable in the dominant and nondominant eyes. Regardless of dominance, the left eyes in the study cohort had a greater statistically significant difference in superior RNFL thickness ( P < 0.05), which correlated with increased central macular thickness. Conclusion: Ocular dominance occurred mostly in the right eye. The RNFL thickness profile is not associated with ocular dominance in emmetropic and mild myopic individuals with normal best corrected visual acuity.