Multifocal Electroretinogram and Short-Wavelength Automated PerimetryMeasures in Diabetic Eyes With Little or No Retinopathy

Objective

To compare severity and locations of abnormalities detected by the multifocalelectroretinogram (mfERG) and short-wavelength automated perimetry (SWAP)in diabetic eyes with early or no retinopathy.

Methods

One eye from each of 22 patients with diabetes mellitus who had earlyretinopathy and 18 patients with diabetes mellitus who had no retinopathywere tested on mfERG and SWAP. The mfERG implicit times were interpolatedbased on SWAP stimulus locations and compared with normative values obtainedfrom 30 age-similar control subjects. The SWAP total threshold deviationswere analyzed using an age-based control data set from 255 healthy subjects.Thezscores of both measures were derived to allowmeasurement comparisons.

Results

Most responses for the 2 measurements were subnormal in both groupswith diabetes mellitus. The 2 measurements showed a similar number of significantabnormalities (zscore ≥2), about 40% and 20%of responses for diabetic patients with retinopathy and diabetic patientswith no retinopathy, respectively. Local mfERG and SWAP results showed somespatial agreement for subjects with retinopathy (r = –0.38,P<.001) but not for those with no retinopathy.

Conclusions

Both mfERG and SWAP are sensitive measurements of diabetic dysfunction,even prior to retinopathy. The lack of spatial correspondence between mfERGand SWAP abnormalities in diabetic patients with no retinopathy reflects overlapping,but different, retinal anomalies in early diabetic eye disease.