Effect of refractive errors on multifocal VEP responses and standard automated perimetry tests in a single population.

BACKGROUND

We have previously reported that the degree of signal-to-noise ratio (SNR) distribution overlaps between a signal window and a noise window in multifocal VEP (mfVEP) responses, which is determined by the area under the receiver-operating characteristic curve termed SNR-AUC, can quantitatively detect glaucomatous visual functional damage. However, the effect of high myopia on this parameter is not yet known.

METHODS

SNR-AUC, total deviation, and retinal sensitivity on the Humphrey visual field (HVF) test were compared among 34 eyes>-6 diopters (control) and 21 eyes≤-6 diopters (high myopia), both of which were ophthalmoscopically normal and had a best-corrected visual acuity of 20/20. The mfVEP and HVF parameters were obtained from stimulus areas that corresponded to both HVF 24-2 and 10-2 programs.

RESULTS

Both the HVF 24-2 total deviation and the SNR-AUC obtained from 60 sectors in high-myopia patients were significantly lower compared with controls (P=0.045 and P=0.003, respectively). The SNR-AUC obtained from the central 36 sectors that corresponded to the HVF 10-2 area in high-myopia patients was also significantly lower than that of the controls (P=0.01). Multiple regression analyses demonstrated that age and refractive error were significantly associated with retinal sensitivity on the HVF 24-2 and SNR-AUC for the whole field and central field, respectively.

CONCLUSIONS

High myopia reduces the SNR-AUC of mfVEP responses, even with refractive correction. A normative database should be separately established for high myopes to evaluate the mfVEP responses obtained from highly myopic glaucoma patients.