Multifocal electroretinogram and short-wavelength automated perimetry measures in diabetic eyes with little or no retinopathy.

OBJECTIVE: To compare severity and locations of abnormalities detected by the multifocal electroretinogram (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 early retinopathy and 18 patients with diabetes mellitus who had no retinopathy were tested on mfERG and SWAP. The mfERG implicit times were interpolated based on SWAP stimulus locations and compared with normative values obtained from 30 age-similar control subjects. The SWAP total threshold deviations were analyzed using an age-based control data set from 255 healthy subjects. The z scores of both measures were derived to allow measurement comparisons.
RESULTS: Most responses for the 2 measurements were subnormal in both groups with diabetes mellitus. The 2 measurements showed a similar number of significant abnormalities (z score >/=2), about 40% and 20% of responses for diabetic patients with retinopathy and diabetic patients with no retinopathy, respectively. Local mfERG and SWAP results showed some spatial 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 mfERG and SWAP abnormalities in diabetic patients with no retinopathy reflects overlapping, but different, retinal anomalies in early diabetic eye disease.