Validity and interpretation of Amsler grid reports.
OBJECTIVE
To compare the reports of scotomas and metamorphosia in standard and threshold Amsler grid testing with the location and extent of scotomas in the macular region as determined by standard and threshold fundus perimetry.


METHODS
Fundus perimetry determined the existence, size, and retinal location of macular scotomas. Amsler grid testing was performed with the scanning laser ophthalmoscope and the TA-300 system (Stereo Optical, Chicago, Ill). All testing was done at both standard and threshold light conditions.


METHODS
Fifty-five patients with vision loss in the macular region and 10 normally sighted subjects.


RESULTS
Nearly half of the standard and threshold scotomas were not detected by Amsler grid testing. For scotomas of 6 degrees or less in diameter, 77% of standard and 87% of threshold scotomas were not detected by Amsler grid testing. Of the eyes with central scotomas involving the fovea, 66% used an eccentric preferred retinal locus for fixating the center of the grid. Finally, more than half of the distortion reported in Amsler grids was at the retinal area that corresponded to the scotoma area, not a nonscotoma retinal area.


CONCLUSIONS
Amsler grid reports have poor validity and cannot be accurately interpreted for use in the clinical diagnosis of retinal defects.
Lions Vision Center, Wilmer Institute, Johns Hopkins University School of Medicine, Baltimore, Md.
R A
RA
Schuchard
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D006801:Humans; D008875:Middle Aged; D015203:Reproducibility of Results; D012607:Scotoma / Q000175:diagnosis*; D012680:Sensitivity and Specificity; D014786:Vision Disorders / Q000175:diagnosis; D014787:Vision Tests / Q000295:instrumentation / Q000379:methods*; D014792:Visual Acuity; D058609:Visual Field Tests; D014794:Visual Fields