Axial Length-Driven Anisometropia in Cornea Plana Spectrum with Alternating Exotropia: A Case Report

Abstract

Introduction: Cornea plana is a rare congenital corneal disorder characterised by marked corneal flattening, often with microcornea and shallow anterior chambers. It is classically associated with high hyperopia and accommodative esotropia. Case Presentation: We report a 35-year-old woman with a cornea plana spectrum phenotype in whom cycloplegic refraction revealed marked anisometropia (hyperopic astigmatism in the right eye and myopic astigmatism in the left eye) together with an alternating exotropia. Swept-source optical biometry demonstrated interocular axial length asymmetry, plausibly offsetting reduced corneal power to different degrees between the eyes and explaining the divergent refractive outcomes. This case highlights that axial length can substantially modify refractive expression in cornea plana spectrum phenotypes and that associated strabismus may not be limited to convergence-driven esodeviations. Conclusion: This case provides an educational example of how axial length asymmetry can modify the refractive expression of corneal hypopower in a cornea plana spectrum phenotype. It also illustrates that ocular alignment findings in this setting should be interpreted in the context of refractive development, visual acuity, and sensory status.