Progression and topographic subtypes of Terrien marginal degeneration

To report long-term outcomes and to search for immunological and genetic risk factors in Terrien marginal degeneration (TMD).

Retrospective, in part prospective, hospital-based longitudinal follow-up study of 32 eyes of 16 Finnish patients from 2012 to 2023. Median follow-up was 7.3 years (range, 0.3-15.2). Symptoms, best corrected visual acuity, pattern in axial power map, astigmatism, corneal thickness, higher order irregularity, cavities, progression and human leukocyte antigen genes were analysed. In 13 blood samples, 483 corneal and inflammatory disease-related genes were analysed with exome sequencing.

The median age at first examination was 61 years (range, 13-89). Eleven (69%) patients were male, and 13 (81%) had bilateral disease. The median annual rate of progression of topographic astigmatism and new thinning was 0.03 D (range, -1.50 to 3.60) and 12.9 μm (range, -107.8 to 93.0), respectively; 0.15 D (range -1.50 to 1.17) and 21.6 μm (range, 1.3-93.0) in 6 (38%) patients with fast progression, and 0.02 D (range, -0.06 to 3.60) and 4.1 μm (range, -107.8 to 24.7) in 10 (72%) patients with slow progression. Topographic pattern, unilaterality, cavities, sectoral hyperaemia, poor response to medical treatment and new thinning after surgery were associated with fast progression. Thickness at maximal thinning fell below 450 μm only with fast progression. Five eyes changed the topographic pattern. Coexisting keratitis fugax hereditaria was found in one patient.

A subtype of TMD progresses faster. The most sensitive indicators of progression were thinning and topographic astigmatism. No shared genetic cause for TMD was identified.