Temporal Protrusion of the Optic Disc Implicated in Central Visual Field Abnormalities in High Myopia: Two Case Reports

Abstract

Introduction: Severe central visual field defects are frequently observed in highly myopic eyes. This report details 2 cases of central visual field defects in individuals with high myopia, characterized by an unusual temporal protrusion of the optic disc, a feature not previously documented.

Case presentation: Two patients, a 54-year-old man and a 65-year-old woman, were diagnosed with high myopia in their left eyes, displaying an outward protrusion of the optic disc toward the macula. Swept-source optical coherence tomography revealed a focal lamina cribrosa defect at the temporal edge of the protruding optic disc, corresponding to the papillomacular bundle area of retinal nerve fibers, which exhibited thinning around the focal lamina cribrosa defect. Visual field examination indicated a central visual field defect in the affected eyes, which pattern corresponded to the papillomacular bundle responsible area.

Conclusion: The emergence of a temporal protrusion in the optic disc may lead to a focal lamina cribrosa defect, resulting in a central visual field defect in highly myopic eyes. This distinctive optic disc feature may constitute a critical risk factor for a central visual field defect. Hence, optic disc protrusion in high myopia warrants attention, necessitating careful ophthalmic examinations for central visual field defects.

Keywords: Focal lamina cribrosa defect; High myopia; Optic disc; Visual field.