A comparison between microperimetry and standard achromatic perimetry of the central visual field in eyes with glaucomatous paracentral visual-field defects.

BACKGROUND AND AIMS: The aim was to correlate retinal sensitivity as determined by scanning laser ophthalmoscope microperimetry (SLO-MP) in glaucomatous eyes with paracentral visual field (VF) defects detected by standard automated perimetry (SAP).
METHODS: Twenty eyes with glaucomatous optic neuropathy and an SAP VF defect involving the central 16 test points (at least one point with p<1% in the 24-2 VF) were enrolled. Eyes with diseases other than glaucoma were excluded. All patients underwent SLO-MP and SAP of the central 10 degrees . Results from each eye were divided into four quadrants for analysis. Normal and abnormal quadrants by SAP were compared with the corresponding normal and abnormal quadrants by SLO-MP. Regression analysis was used to correlate the mean threshold values (dB) of SLO-MP and SAP in each quadrant. Macular optical coherence tomography (OCT) was performed when there was a disagreement between functional tests.
RESULTS: The mean age and VF mean deviation were 60.8 (13.4) years and -7.3 (6.1) dB, respectively. There was a significant correlation between SLO-MP and SAP results in all quadrants (r(2)> or =0.68, p<0.001). All abnormal SAP quadrants had a corresponding abnormal SLO-MP quadrant. However, 21% of the normal SAP quadrants had an abnormal corresponding microperimetry result; a corresponding significant reduction in total macular thickness measured by OCT was present in 75% of these quadrants.
CONCLUSIONS: Macular sensitivity evaluated by SLO-MP correlates significantly with SAP paracentral VF defects. SLO-MP detected retinal sensitivity reduction in areas of OCT structural damage with normal SAP and suggests that subtle paracentral functional deficits may be present in many more eyes with established glaucoma than generally assumed.