title: Rarebit perimetry in normal subjects: test-retest variability, learning effect, normative range, influence of optical defocus, and cataract extraction.
abstract: OBJECTIVE
  To study normative ranges, learning effect (LE), test-retest variability (TRV), and influence of blur and cataract in normal subjects by using rarebit perimetry (RBP).
  
  
  METHODS
  Seventy-five normal subjects underwent visual field (VF) testing with standard automated perimetry (SAP) and RBP. LE and TRV for RBP were assessed in repeated examinations conducted on four different days. LE was evaluated by comparing results from the first with those of the other three sessions. TRV was studied by calculating differences between retest for each combination of single tests. The blur effect was evaluated by repeated tests with spherical lenses added to the optimum refractive correction (+/-1.00 to +/-6.00 D). The cataract effect was studied in 23 subjects who underwent RBP 1 week before and 1 month after cataract surgery. Mean hit rate (MHR) and mean miss rate (MMR) were analyzed for single areas and test duration.
  
  
  RESULTS
  The mean MHR was 91% +/- 5.7% (range, 78%-99%); the mean MMR ranged from 4.0% to 13.8%. MHR significantly decreased with age (mean, 0.21%/year). Mean test time was 268 +/- 34.1 seconds. No significant LE was observed. TRV was significantly higher in the central VF zone and in elderly subjects. MHR increased with refractive blur and significantly decreased after cataract surgery. Effects of blur and cataract extraction were significantly higher in the central VF zone, especially in elderly subjects.
  
  
  CONCLUSIONS
  RBP is a rapid and easily accessible VF test. RBP testing did not show a significant LE; however, inter- and intrasubject variability were consistent. Blur and media opacities may give false-positive results in RBP, especially in the central VF, and should be considered.
authors.affiliation: Department of Ophthalmology, S Maria della Misericordia Hospital, Udine, Italy.
authors.forename: Maria Letizia
authors.initials: ML
authors.lastname: Salvetat
authors.forename: Marco
authors.initials: M
authors.lastname: Zeppieri
authors.forename: Lucia
authors.initials: L
authors.lastname: Parisi
authors.forename: Paolo
authors.initials: P
authors.lastname: Brusini
mesh_terms: D000328:Adult; D000368:Aged; D002386:Cataract / Q000503:physiopathology*; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D007858:Learning / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D018918:Phacoemulsification; D011237:Predictive Value of Tests; D012016:Reference Values; D012030:Refractive Errors / Q000503:physiopathology*; D015203:Reproducibility of Results; D014786:Vision Disorders / Q000503:physiopathology*; D058609:Visual Field Tests / Q000379:methods*; D014794:Visual Fields / Q000502:physiology*