Abstract
Diseases that affect photoreceptor structure, function and survival are among the most challenging conditions to treat in ophthalmology. Photoreceptors are essential for vision, and cone photoreceptors mediate visual acuity and visual field, traditional outcome measures for clinical trials. Studying photoreceptor structure and function with high resolution in living eyes facilitates assessment of how different diseases impact photoreceptors during disease progression and in response to new treatments. Adaptive optics images of photoreceptor structure and, more recently, function have shed light on macular cone and rod survival in eyes with macular telangiectasia type 2, foveolitis and many inherited rod-cone and cone-rod degenerations. Studies have characterized the short-term repeatability and intergrader variability of cone spacing measures in eyes with retinal degeneration using adaptive optics. Finally, correlating measures of photoreceptor structure with visual function permits assessment of how retinal pathology affects vision. Adaptive optics derived measures of macular cone structure may be more sensitive measures of disease progression than traditional clinical measures of visual acuity in eyes with retinal degeneration. Studies describing the reliability and variability of cone structure and function is essential to validate adaptive optics scanning laser ophthalmoscopy-derived metrics for use as longitudinal outcome measures in clinical trials.