Abstract
Purpose: :
To determine the effect of age-related cataract for CFF perimetry in otherwise normal individuals who were naïve to both Standard Automated Perimetry (SAP) and Critical Flicker Fusion (CFF) Perimetry.
Methods: :
The cohort comprised 17 individuals aged between 50 and 79 years (mean age 68.8 years, SD 9.8) exhibiting age-related cataract in at least one eye. All individuals underwent a clinical examination at baseline including SAP and CFF perimetry using Program G1, stimulus size III and the TOP strategy of the Octopus 311. The stimulus luminance for CFF perimetry was at the maximum for the perimeter (4800 asb). Cataract type and severity was classified by LOCS III. Five individuals had anterior cortical cataract (ACC) in the more severely affected eye, 4 posterior subcapsular cataract (PSC), 6 nuclear cataract (NC) and 2 with either ACC and NC or ACC and PSC, combined. After an interval of one week, all individuals underwent both CFF perimetry and SAP in an identical manner to that at baseline and this was repeated on two further occasions each separated by one week. The order of the type of perimetry was randomized between individuals and kept constant with an individual over the four sessions of perimetry. The right eye was always examined before that of the left eye. The results were analysed for the fourth visit, in order to minimise the influence of the learning effect, and for the eye with the more severe cataract, in terms of the Mean Defect (MD) and the Loss Variance (LV) as a function of cataract type and severity.
Results: :
Age-related cataract reduced the height of the visual field to a similar extent for both SAP (group mean MD 1.8dB; SD 3.4; range -1.8 to 10.2dB) and CFF perimetry (group mean MD 1.7Hz; SD 5.3; range -5.0 to 12.8Hz). The attenuation increased with increase in cataract severity. There was a tendency for PSC to exhibit a more adverse effect for SAP compared to CFF.
Conclusions: :
For CFF perimetry, the presence of cataract will inhibit the identification of diffuse loss arising from neural damage and, in this regard, the technique offers little advantage over that of SAP.
Keywords: visual fields • cataract • perimetry