Abstract
Purpose: :
To study cone photoreceptor structure and function in retinitis pigmentosa (RP) patients treated with sustained-release ciliary neurotrophic factor (CNTF).
Methods: :
Longitudinal study within a Phase 2 trial of an RP patient treated with sustained-release CNTF in one eye with the fellow eye as control. Adaptive Optics Scanning Laser Ophthalmoscopy (AOSLO) provided high-resolution retinal images of regions of interest (ROIs) with unambiguous cones at baseline, 3, 6, 12, 18, and 24 months. Measures of retinal structure were correlated with visual function including visual acuity (VA), automated perimetry, and full-field electroretinography (ERG).
Results: :
A 37 year old woman with autosomal dominant RP and a rhodopsin mutation (Gly51Val) showed no significant changes in VA, foveal or mean visual field sensitivity, or ERG in either eye over 24 months. Baseline cone spacing was significantly higher than normal at all ROIs in the control eye (n=7) and 88% of ROIs (n=8) in the CNTF-treated eye. Linear regression over 24 months revealed a statistically significant increase in cone spacing (p<0.05) for 71% of ROIs in the control eye, compared to 12.5% of ROIs in the CNTF-treated eye. Cone spacing increased at a rate of 0.12 arcminutes/year in the control eye and 0.034 arcminutes/year in the CNTF-treated eye (p=0.001).
Conclusions: :
AOSLO images showed cone photoreceptor loss during disease progression in a patient with RP. Cone spacing increased at a significantly higher rate in the control eye compared to the CNTF-treated eye over 24 months. The study demonstrates the first images of cone photoreceptors monitored longitudinally during disease progression and in response to sustained-release CNTF therapy in a patient with RP. Although no significant changes were observed in visual function, significant differences in the rate of increased cone spacing suggest that CNTF may slow cone photoreceptor loss in RP patients.
Clinical Trial: :
www.clinicaltrials.gov NCT00447980
Keywords: retinal degenerations: hereditary • imaging/image analysis: clinical • photoreceptors