Peripheral Hypertrophic Subepithelial Corneal Degeneration

Peripheral hypertrophic subepithelial corneal degeneration (PHSCD) was first described by Maust and Raber in 2003, who reported 6 patients with peripheral, symmetric, and bilateral subepithelial fibrotic lesions in the periphery and mid-periphery of the cornea. The authors explained that although similar to Salzmann nodular degeneration, these 6 women had ocular irritation symptoms and no preceding episodes of keratitis or inflammation. Since its initial description, several cases have been reported describing PHSCD as an isolated diagnosis. Many of these cases have reported risk factors, various clinical presentations, diagnostic findings, and management strategies for patients with PHSCD.  PHSCD is currently understood to be a relatively rare, benign ocular condition characterized by subepithelial fibrous tissue growth in the peripheral cornea. PHSCD often presents as an asymptomatic condition but can occasionally cause discomfort or visual disturbances depending on the extent and location of the degeneration. This degeneration is distinct from other corneal dystrophies and degenerations due to its specific peripheral location and the nature of the subepithelial deposits found between the epithelium and the Bowman layer. These deposits are composed mainly of fibrous tissue and can lead to a whitish, opaque appearance at the affected sites; the subepithelial layer is crucial for maintaining corneal transparency and overall ocular health. However, extensive peripheral involvement can sometimes encroach upon the central cornea, potentially affecting vision. Patients with PHSCD often present with ocular irritation or dry eye symptoms such as redness, tearing, or a foreign body sensation. Asymptomatic presentations are well-documented; in these cases, PHSCD is an incidental finding. The diagnosis of PHSCD is primarily clinical, based on the characteristic appearance of the cornea during slit-lamp examination. The natural course of PHSCD varies among individuals. In some cases, the condition may stabilize without significant progression, whereas in others, the fibrous tissue proliferation may continue gradually over time.  Management of PHSCD focuses on alleviating symptoms, addressing visual impairment, and preventing further progression. Treatment options include lubricating eye drops to reduce discomfort and irritation and anti-inflammatory medications to manage underlying ocular surface inflammation. In severe cases, surgical removal of the fibrous tissue may be considered, although this is rarely necessary. Surgical management includes manual superficial keratectomy or phototherapeutic keratectomy. Regular follow-up with an ophthalmologist is essential for monitoring the condition and adjusting the management plan. Understanding the anatomy, natural history, and patterns of spread of PHSCD is crucial for effective diagnosis and management. Regular ophthalmic evaluations are essential for ensuring timely intervention and preserving ocular health.