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° 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° 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° off fixation, moderate to mild defects were seen in 10-52% eyes, and 10% eyes showed involvement up to 4° from the fixation. Eyes with arcuate scotoma had an absolute scotoma on MP in 95% of eyes, 6-10° from fixation, with extension up to 2° 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° from fixation.