title: The robustness of various forms of perimetry to different levels of induced intraocular stray light.
abstract: OBJECTIVE
  To compare directly the robustness of standard automated perimetry (SAP), short-wavelength automated perimetry (SWAP), frequency-doubling perimetry (FDP), and grating-resolution perimetry (GRP) stimuli to different degrees of intraocular stray light induced by commercially available opacity-containing filters.
  
  
  METHODS
  Five white opacity filters of increasing density were used to simulate the typical forward light scatter and stray light values associated with age-related lens opacification and significant cataract. The individually induced intraocular stray light value for each filter was quantified with a stray light meter and plotted against individual perimetric thresholds for the right eyes of three normally sighted trained observers for SAP, SWAP, FDP, and GRP.
  
  
  RESULTS
  All tests were significantly but differently affected by increasing stray light. Overall average declines over a 1 log unit change in the stray light values were as follows: SAP, 4.85 dB; SWAP, 9.03 dB; FDP, 4.29 dB; and GRP, 1.36 dB. Standardized (z) scores were calculated after normalization to the spread of the normative data values for each instrument. These indicated that the standardized changes from baseline over the range of the five filters per log stray light unit were as follows: SAP, 2.177; SWAP, 1.96; FDP, 1.277; and GRP, 1.04.
  
  
  CONCLUSIONS
  The increased stray light values induced by cataract-simulating filters has a significant effect on all tests. However, GRP, which is known to be limited by retinal sampling rather than contrast, remains the most robust of the tests to the effects of intraocular stray light. The degree to which the normative "sensitivity" range for different types of perimetry might incorporate a component caused by individual differences in intraocular stray light is discussed and requires further research.
authors.affiliation: School of Biomedical Sciences, University of Ulster, Coleraine, Northern Ireland, United Kingdom. rs.anderson@ulster.ac.uk
authors.forename: Roger S
authors.initials: RS
authors.lastname: Anderson
authors.forename: Tony
authors.initials: T
authors.lastname: Redmond
authors.forename: D Rodney
authors.initials: DR
authors.lastname: McDowell
authors.forename: Karen M M
authors.initials: KM
authors.lastname: Breslin
authors.forename: Margarita B
authors.initials: MB
authors.lastname: Zlatkova
mesh_terms: D000328:Adult; D000375:Aging / Q000502:physiology; D002386:Cataract / Q000503:physiopathology*; D006801:Humans; D007908:Lens, Crystalline / Q000528:radiation effects; D008027:Light; D008875:Middle Aged; D008954:Models, Biological; D012542:Scattering, Radiation; D012680:Sensitivity and Specificity; D014786:Vision Disorders / Q000503:physiopathology*; D058609:Visual Field Tests; D014794:Visual Fields