Abstract
Purpose: :
To compare standard automated perimetry (SAP–SITA) and 24–2 frequency doubling perimetry (FDP–Matrix) ability in detecting visual field abnormalities in patients with glaucomatous optic neuropathy.
Methods: :
This study included 94 eyes of 94 patients with glaucomatous optic neuropathy (GON) and 167 eyes of 167 normal participants with healthy appearance of the optic nerve head. Diagnosis was based on masked assessment of optic disk stereophotographs. All subjects had reliable SAP–SITA and FDP–Matrix exams performed within 3 weeks of each other. Abnormal visual function was defined as any of the following: 1. glaucoma hemifield test outside of 99% normal limits; 2. pattern standard deviation outside the 95% normal limits; 3. the presence of a cluster of three or more contiguous points at the Total Deviation (TD) Plot with p < 5%, with at least one point having p < 1%. Also, test time, global indices and number of abnormal points on the total deviation (TD) plot were compared between the two tests.
Results: :
FDP–Matrix and SAP–SITA detected visual function abnormalities in 53% and 46% of GON eyes, respectively (p = 0.265). The agreement between both exams was fair (Κ = 0.386), as only 34% GON eyes had both VF tests identified as abnormal. FDP–Matrix and SAP–SITA detected an abnormal visual function in 27% and 16% of healthy eyes, respectively (p = 0.010). The mean test time of FDP–Matrix was longer than SAP–SITA (316 ± 17 vs. 297 ± 46 seconds; respectively, p < 0.001) and test time increased significantly with visual field damage in both FDP and SAP (r = – 0.25; p < 0.001 and r = – 0.67; p < 0.001; respectively). Correlation of FDP and SAP global indices were good (r = 0.66 for MD and r = 0.78 for PSD). Among all 94 GON eyes there were no significant difference on the number of abnormal points on TD plot between FDP–Matrix and SAP–SITA (9.05 ± 12.20 and 8.25 ± 11.62; respectively; p = 0.329).
Conclusions: :
Each visual field test identified visual function defects in different subset of patients with GON. However, the FDP–matrix produced a significantly higher false positive result. If the VF defects observed in our study are reproducible, a combination of SAP–SITA and FDP–Matrix may improve detection of functional loss in eyes with GON.
Keywords: visual fields • perimetry • optic disc