Assessing Photoreceptor Status in Retinal Dystrophies: From High-Resolution Imaging to Functional Vision.

PURPOSE: To describe the value of integrating phenotype/genotype data, disease staging, and evaluation of functional vision in patient-centered management of retinal dystrophies. METHODS: (1) Cross-sectional structure-function and retrospective longitudinal studies to assess the correlations between standard fundus autofluorescence (FAF), optical coherence tomography, visual acuity (VA), and perimetry (visual field [VF]) examinations to evaluate photoreceptor functional loss in a cohort of patients with rod-cone dystrophy (RCD); (2) flood-illumination adaptive optics (FIAO) imaging focusing on photoreceptor misalignment and orientation of outer segments; and (3) evaluation of the impact of visual impairment in daily life activities, based on functional (visual and mobility) vision assessment in a naturalistic environment in visually impaired subjects with RCD and subjects treated with LuxturnaⓇ for RPE65-related Leber congenital amaurosis before and after therapy. RESULTS: The results of the cross-sectional transversal study showed that (1) VA and macular sensitivity were weakly correlated with the structural variables; and (2) functional impairment (VF) was correlated with reduction of anatomical markers of photoreceptor structure and increased width of autofluorescent ring. The dimensions of the ring of increased FAF evolved faster. Other criteria that differed among groups were the lengths of the ellipsoid zone, the external limiting membrane, and the foveal thickness. FIAO revealed a variety of phenotypes: paradoxical visibility of foveal cones; heterogeneous brightness of cones; dim, inner segment-like, and RPE-like mosaic. Directional illumination by varying orientation of incident light (Stiles-Crawford effect) and the amount of side illumination (gaze-dependent imaging) affected photoreceptor visibility. Mobility assessment under different lighting conditions showed correlation with VF, VA, contrast sensitivity (CS), and dark adaptation, with different predictive values depending on mobility study paradigms and illumination level. At high illumination level (235 lux), VF was a predictor for all mobility performance models. Under low illumination (1 and 2 lux), VF was the most significant predictor of mobility performance variables, while CS best explained the number of collisions and segments. In subjects treated with LuxturnaⓇ, a very favorable impact on travel speed and reduction in the number of collisions, especially at low luminance, was observable 6 months following injection, in both children and adults. CONCLUSIONS: Our results suggest the benefit of development and implementation of quantitative and reproducible tools to evaluate the status of photoreceptors and the impact of both visual impairment and novel therapies in real-life conditions. NOTE: Publication of this article is sponsored by the American Ophthalmological Society.

Threshold levels of visual field and acuity loss related to significant decreases in the quality of life and emotional states of patients with retinitis pigmentosa.

INTRODUCTION: Retinitis pigmentosa (RP) is an inherited retinal disorder, characterized by photoreceptor degeneration inducing progressive vision loss. This study evaluates its impact on quality of life (QOL) and emotional states of patients affected by RP. METHODS: A cross-sectional study was conducted on 60 RP patients diagnosed with rod-cone dystrophy and on 20 control subjects. The RP population has been divided into 3 groups according to visual field (VF) and visual acuity (VA) impairments. Concurrently, scores of self-reported QOL (25-item National Eye Institute Visual Functioning Questionnaire) and of the Hospital Anxiety and Depression Scale for anxiety/depression assessments were collected. RESULTS: For the QOL composite score, we noticed consistent differences between all VF and VA affected groups and their control group. We also found significant differences between both the most affected VF group (VF1: ØVF <20°) and VA group (VA1: VA <0.3) compared to other VF and VA groups. For anxiety/depression scores, consistent differences have been found between the control group and VF1 and VA1, respectively. CONCLUSIONS: This work determines that, for RP patients, a significant QOL and emotional state deterioration correlates with a residual VF diameter below 20° and a VA lower than 0.3. It introduces, for the first time, thresholds to be used in visual restoration or visual preservation therapies to improve QOL of RP patients.