Functional Evaluation Of The Macular Area In Early Glaucoma Using Microperimetry

Purpose: To evaluate the central visual field by microperimetry (MP), in early glaucoma. Methods: Consecutive perimetrically experienced patients with a single nasal step or arcuate scotoma and 14 control eyes underwent MP. Retinal sensitivity on MP was mapped for frequency and depth of loss in the central 10 degrees around fixation. Results: Twenty-one eyes had a single nasal step and 19 eyes with single arcuate scotoma on standard automated perimetry (SAP), with central 10 degrees being normal on 30-2 and 10-2 perimetry. The average mean sensitivity on MP, in glaucomatous and control eyes was 11.8 +/- 3.9 dB and 16.6 +/- 1.2 dB, respectively, P = 0.0004. The average mean defect on MP-1, in glaucomatous and control eyes was- 6.5 +/- 2.0 dB and- 3.0 +/- 1.2 Db, respectively, P = 0.05. The corresponding retinal hemisphere showed significant defects in MP. In eyes with single nasal steps, an absolute scotoma was seen in 14-28% of eyes 8-10 degrees off fixation, moderate to mild defects were seen in 10-52% eyes, and 10% eyes showed involvement up to 4 degrees from the fixation. Eyes with arcuate scotoma had an absolute scotoma on MP in 95% of eyes, 6-10 degrees from fixation, with extension up to 2 degrees from fixation in 21%. In glaucomatous eyes, the normal hemisphere on SAP showed a mild defect on MP in 43%. Control eyes did not show any defect in SAP or MP. Conclusion: A significant loss of central retinal sensitivity is recorded on MP in early glaucomatous neuropathy as compared to SAP. Paramacular absolute defects were seen at 6-10 degrees from fixation.