OCT-Based Measurement of RNFL Thickness in Pediatric Strabismic Amblyopia

Background: Strabismic amblyopia remains a major cause of unilateral visual impairment in children, arising from abnormal binocular interaction during the sensitive period of visual development. While functional deficits such as reduced visual acuity and contrast sensitivity are well-documented, the presence of structural retinal alterations, particularly in the peripapillary retinal nerve fiber layer (RNFL), is debated. Spectral-domain optical coherence tomography (SDOCT) provides high-resolution, non-invasive quantification of RNFL thickness, enabling objective evaluation of potential neuro-retinal changes in amblyopic eyes. Aim: To compare peripapillary RNFL thickness between amblyopic and fellow eyes in children aged 5–15 years with unilateral strabismic amblyopia. Methods: This cross-sectional purposive observational study enrolled 50 children (mean age 9.4 years; 26 males, 24 females) with unilateral strabismic amblyopia (30 esotropia, 20 exotropia; equal laterality). Comprehensive ophthalmic examination included best-corrected visual acuity (BCVA) and SD-OCT peripapillary RNFL imaging. Amblyopia severity: mild (BCVA 6/18, n=8), moderate (6/24, n=12), severe (6/36 or worse, n=30). Average and quadrant-wise (superior, inferior, nasal, temporal) RNFL thicknesses were compared using paired t-tests. Results: Amblyopic eyes showed significantly reduced average RNFL thickness (90.85 ± 6.4 µm) versus fellow eyes (102.10 ± 5.9 µm; mean difference 11.25 µm, p < 0.05). Pronounced thinning occurred in temporal (62.40 µm) and inferior quadrants, followed by nasal (71.85 µm), with relative superior preservation (114.20 µm). Thinning correlated strongly with amblyopia severity and poorer BCVA in amblyopic eyes. Conclusion: Unilateral strabismic amblyopia in children is linked to significant peripapillary RNFL thinning, especially temporally and inferiorly, indicating structural neuro-retinal involvement beyond cortical suppression. SD-OCT offers a reliable objective biomarker for assessing and monitoring amblyopic eyes.