Cone- and rod-mediated dark adaptation impairment in age-related maculopathy.

Academic Article

Abstract

  • OBJECTIVE: To examine impairment in cone- versus rod-mediated dark adaptation in the parafovea of persons with age-related maculopathy (ARM). DESIGN: Cross-sectional. PARTICIPANTS: Older 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. METHODS: Dark adaptation, both cone- and rod-mediated components, was measured with a modified Humphrey Field Analyzer using a target located 12 degrees 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 MEASURES: Cone- and rod-mediated parameters of dark adaptation. RESULTS: Compared 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. CONCLUSIONS: Disturbances in rod-mediated but not cone-mediated dark adaptation in the parafovea at 12 degrees in the inferior field on the vertical meridian are characteristic of ARM even in its early phases.
  • Keywords

  • Aged, Cross-Sectional Studies, Dark Adaptation, Female, Humans, Macular Degeneration, Male, Photic Stimulation, Retinal Cone Photoreceptor Cells, Retinal Rod Photoreceptor Cells, Surveys and Questionnaires, Vision, Ocular, Visual Acuity, Visual Field Tests, Visual Fields
  • Digital Object Identifier (doi)

    Author List

  • Owsley C; McGwin G; Jackson GR; Kallies K; Clark M
  • Start Page

  • 1728
  • End Page

  • 1735
  • Volume

  • 114
  • Issue

  • 9