Unilateral corneal ectasia following trigeminal schwannoma resection with chronic neurogenic eye rubbing.

Background: Keratoconus (KC) is typically a bilateral, progressive corneal ectasia. Unilateral ectasia is uncommon and has been associated with chronic mechanical stress, such as eye rubbing. Although unilateral ectasia related to unilateral rubbing has been reported, the neurogenic driver of such behavior is less commonly highlighted. We describe a case of late-onset unilateral ectasia developing after trigeminal schwannoma resection. Case presentation: A 50-year-old man with a history of left cerebellopontine angle schwannoma resection developed persistent left-sided facial hypoesthesia followed by chronic unilateral eye rubbing. Approximately a decade later, he noticed progressive visual decline in the left eye (OS). Examination revealed advanced unilateral ectasia in OS, with high irregular astigmatism (4.8 D), and a corneal thinnest point of 439 μm, a Fleischer ring, and severely reduced corneal sensitivity on the Cochet-Bonnet aesthesiometer. The right eye (OD) remained unaffected, with normal corneal tomography and preserved corneal sensitivity. No family history or systemic risk factors for KC were identified, supporting a localized mechanical contribution. Conclusion: This case supports a plausible association between trigeminal nerve dysfunction, chronic unilateral eye rubbing, and subsequent corneal ectasia. It highlights the importance of recognizing neurogenic drivers of eye rubbing, performing careful ocular surface and corneal evaluation, and closely monitoring such patients for secondary corneal changes.