Purpose:
To determine the relationship between equivalent visual field areas obtained with the Humphrey Field Analayzer perimeter (HFA) and the Octopus perimeter (OP).
Methods:
One hundred and thirty-four consecutive patients with open-angle glaucoma were prospectively selected. Eligible subjects had to have intraocular pressure higher than 21mmHg and glaucomatous optic nerve head morphology. All participants underwent a reliable white-on-white automated perimetry (SAP) with the HFA (Humphrey Zeiss Systems; 24-2 SITA Standard strategy) and a reliable SAP with the OP (Haag-Streit International; TOP test strategy). One eye from each subject was randomly chosen unless only one eye met the inclusion criteria. Left eyes were converted to a right eye format. Each of the mean threshold values at each point of the visual field was numbered and considered as a variable for the factor analysis. Factor analyses of the mean threshold values for the SAP test points were performed, independently for each hemifield of each perimetry (HFA and OP), to define regions of related points. Five to six visual field regions for each hemifield and for each perimetry were determined. After checking for a normal distribution of variables, Pearson correlations were calculated between equivalent HFA and Octopus regions.
Results:
Mean age was 60.66 ± 10.35 years. HFA mean deviation was -5.94 ± 4.38 dB while Octopus mean defect was 4.31 ± 3.40 dB (p<0.001). Moderate to strong correlations were found between related regions of both tests. The strongest correlations were found between sector 1 inferior of HFA and sector 1 inferior of OP (0.824, p<0.001) and sector 1 superior of HFA and sector 1 superior of OP (0.699, p<0.001). Indices of HFA correlated well with indices of OP: 0.722 (p<0.001) between mean deviation of HFA and mean defect of OP and -0.720 (p<0.001) between visual field index of HFA and loss variance of OP.
Conclusions:
In general, HFA and OP generated similar visual field regions. Our results are consistent with previous studies, in which the distribution of the visual field regions for the superior and inferior hemifields was reported to be asymmetric. Moderate to strong correlations were found between the different regions. The strongest correlation was observed between inferior nasal regions.
Keywords: visual fields • perimetry • perception