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Cone- and Rod-Mediated Dark Adaptation Impairment in Age-Related Maculopathy

2007; Elsevier BV; Volume: 114; Issue: 9 Linguagem: Inglês

10.1016/j.ophtha.2006.12.023

1549-4713

Cynthia Owsley, Gerald McGwin, Gregory R. Jackson, Katherine Kallies, Mark E. Clark,

Ophthalmology and Visual Impairment Studies

ObjectiveTo examine impairment in cone- versus rod-mediated dark adaptation in the parafovea of persons with age-related maculopathy (ARM).DesignCross-sectional.ParticipantsOlder adults with ARM at various severity levels from early to advanced (n = 83) and in good retinal health (n = 43), as determined by stereo fundus photographs evaluated with the Age-Related Eye Disease Study severity scale.MethodsDark adaptation, both cone- and rod-mediated components, was measured with a modified Humphrey Field Analyzer using a target located 12° in the inferior visual field on the vertical meridian, after exposure to a 98% bleach. Information was collected on self-reported problems for activities at night or under dim illumination (Low Luminance Questionnaire [LLQ]) and for activities during daytime conditions (modified National Eye Institute Visual Function Questionnaire [NEI VFQ]).Main Outcome MeasuresCone- and rod-mediated parameters of dark adaptation.ResultsCompared with older adults in normal retinal health, ARM patients had significant impairments in rod-mediated parameters of dark adaptation (rod–cone break, rod slope, rod sensitivity) (P<0.0001), which were increasingly abnormal as disease severity increased. Cone-mediated parameters (cone time constant and cone sensitivity) were not impaired. Low Luminance Questionnaire scores and NEI VFQ scores decreased with increased ARM severity (P = 0.0004 and P = 0.0005, respectively); the percent decrease in LLQ scores as a function of disease severity was larger in magnitude than the percent decrease in NEI VFQ scores.ConclusionsDisturbances in rod-mediated but not cone-mediated dark adaptation in the parafovea at 12° in the inferior field on the vertical meridian are characteristic of ARM even in its early phases.