ANALYSIS OF HENLE FIBER LAYER AND OUTER RETINAL LAYERS IN CONE DYSTROPHY.

Abstract

Purpose: To evaluate Henle fiber layer (HFL) thickness and volume parameters in patients with cone photoreceptor atrophy with directional optical coherence tomography.

Methods: Macular 20°×20° standard and directional optical coherence tomography images were acquired from patients diagnosed with hereditary cone dystrophy with evident foveal ellipsoid zone defect in optical coherence tomography and age-matched healthy controls. Thickness and volume parameters of HFL, outer nuclear layer (ONL), and retinal layers between ellipsoid zone and Bruch membrane complex (EZ-BM) were calculated from manual segmentation through directional optical coherence tomography images, and comparative analysis is performed.

Results: Twelve eyes of six patients were compared with 12 eyes of six age-matched healthy controls (mean age: 29.5 ± 16.6 and 26.6 ± 3.9 years, respectively; P = 0.162). Patients had lower total HFL volume (0.45 ± 0.03 and 0.85 ± 0.15 mm 3 ; P < 0.001) and mean HFL thickness (16.1 ± 1.1 and 30.1 ± 5.3 µ m; P < 0.001) than healthy controls. Central subfield, parafoveal, and perifoveal ETDRS zone HFL parameters in patients were significantly lower than healthy controls. A centrifugal correlation was found between central outer nuclear layer and the corresponding parafoveal HFL (Spearman rho: 0.785; P < 0.001).

Conclusion: Henle fiber layer assessment might be a useful optical coherence tomography biomarker in patients with cone photoreceptor atrophy. Henle fiber layer thinning is observed in foveal, parafoveal, and perifoveal areas of patients with cone photoreceptor atrophy, while volume reduction in outer nuclear layer and ellipsoid zone and Bruch membrane complex components were limited to central and parafoveal zones.