Anterior segment phenotypic changes in late-onset retinal degeneration with Ser163Arg mutation in CTRP5/C1QTNF5

Late-onset retinal degeneration (L-ORD) is a rare retinal dystrophy with anterior segment (AS) abnormalities, including long anterior zonules (LAZ) and iris atrophy. This investigation evaluates AS changes in a L-ORD cohort.

Prospective, longitudinal study including L-ORD individuals (Ser163Arg) with ocular exam and standard slit-lamp photographs between 2011 and 2022. AS images were merged and assessed for LAZ number and zonule-free zone (ZFZ) radius. Further clinical findings such as iris atrophy patterns were reported descriptively.

Twelve eyes of 6 patients (4 males, median age = 60.5 years) were included, showing a median of 160 (11-372) LAZs, mainly localized superiorly (39%) and inferiorly (24%). There was a high inter-ocular correlation (rs = 0.94, p < 0.01), no difference in LAZ count between eyes (p = 0.82), and an inverse relationship between LAZ and age (r =  - 0.82; p < 0.05). The ZFZ had median 2.1 mm (1.3-5.4), with no inter-ocular difference (p = 0.31). Iris transillumination defects occurred in 11/12 eyes, with 4 major patterns identified: pupillary ruff rarefaction (10/12), patchy atrophy (6/12), notched defects (6/12), and radial streaks (2/12). In a short-term follow-up of 5.9 years, 4 eyes showed a reduction in LAZ count to median 139.5 (67-169) (p = 0.50) and a concomitant increase in ZFZ measurement to median 2.2 (1.7-2.6) (p = 0.17).

This study confirms symmetric LAZs count and ZFZ in L-ORD, with ZFZ measurements smaller than in previous cohorts. A reduction in LAZs count and an increase in ZFZ with age were suggested longitudinally, yet findings need further evaluation as follow-up was limited to two cases.