Linear Interstitial Keratitis: A Report of Two Cases and Review of Literature

Linear interstitial keratitis is an extremely rare variant of interstitial keratitis characterized by horizontal linear stromal infiltrates. This case series aims to expand the existing literature on linear interstitial keratitis by presenting two additional cases. The retrospective series includes two patients treated at a tertiary care hospital, both of whom underwent comprehensive clinical evaluations, including anterior segment optical coherence tomography (AS-OCT), and one patient underwent in vivo confocal microscopy (IVCM). The first patient, a 16-year-old female, presented to our center with a horizontal linear stromal opacity. She responded to topical steroids and was left with a residual scar outside of the visual axis. The second patient, a 31-year-old male with a history of Laser-assisted in situ keratomileusis (LASIK), presented with parallel linear stromal opacities. Both patients exhibited anterior stromal hyperreflectivity on AS-OCT. IVCM revealed hyperreflective needle-like structures in the first case only. Linear interstitial keratitis is a rare and poorly understood variant of interstitial keratitis. In our series, the condition responded to corticosteroid treatment. The second patient is the oldest patient in the literature to be diagnosed with linear interstitial keratitis and the only patient with a history of LASIK. Further studies with long-term follow-up and advanced diagnostic techniques are necessary to further classify the etiology of this rare condition.