Abstract
Purpose::
to study the normative range, reproducibility, learning effect and influence of optical defocus and cataract extraction with Rarebit Perimetry (RBP).
Methods::
Sixty-four normals underwent visual field (VF) testing with Standard Automated Perimetry (SAP) and RBP. Normative ranges were determined for all RBP parameters. RBP learning effect and test-retest variability (TRV) determinations (mean of the differences between paired tests) were based on 4 repeated measures within 3 months in 18 normal subjects. Optical defocus was studied in 13 normals that each underwent consecutive blurred RBP tests with spherical (sf) lenses (from ±1.00D to ±6.00D sf). The effect of cataract extraction was studied in a separate group of 23 patients scheduled for cataract surgery (RBP testing a week before and a month after surgery). Mean Hit Rate (MHR), standard deviation (MHR-SD), Mean Miss Rate (MMR), number of tested areas with hit-rate <90% (#HR<90%), and test duration were analyzed.
Results::
Mean MHR was 92±5.4% (range 80-99%); MHR-SD was 8.4±3.3% (range 3.4-15.2%); mean #HR<90% was 4.3±3.9% (range 0-18%); MMR for single areas ranged from 2.9-11.0%. MHR significantly decreased (mean 0.23%/year) as age increased. Mean RBP test time was 257±26.4 s. No significant learning effect was observed. TRV ranged from: 0±3.6% for MHR, -0.01±3.5% for MHR-SD, -0.02±2.5 for #HR<90% and 0.0±11.1% MMR for individual areas. MHR and MHR-SD increased with the refractive blur (significantly for lenses≥+3D). Tests after cataract surgery showed significant increases in MHR and decreases in MHR-SD. The effect of optical defocus and cataract extraction was significantly higher in the 4 central VF areas.
Conclusions::
The RBP is a rapid and easily accessible VF test. RBP testing did not show a learning effect, however, inter- and intra-subjects variability was high. Blur and media opacities may give false positive results in RBP, especially in the central VF, and should thus be considered.
Keywords: visual fields • perimetry • visual impairment: neuro-ophthalmological disease