Laser Interferometric Visual Acuity in Retinal Diseases

Laser interferometry is used to evaluate the retinal visual function in the eyes with media opacity. Although interferometric acuity was known to be useful to predict postoperative Snellen acuity following cataract extraction, the results are somewhat confusing in the eyes with retinal diseases. The author measured interferometric acuity in 43 eyes from 32 patients who were affected by retinal diseases involving macula and had clear ocular media. Average interferometric acuity was 0.47. Hahn's acuity was 0.46 and correlation index between two acuities was 0.64 meaning moderate degree of correlation. Interferometric acuities were better than Hahn's acuity in 23 eyes(53.5%) and worse in 12 eyes(27.9%). Our results suggest that in eyes with macular lesion, interferometric acuity is not sufficient to predict Hahn's acuity although it has some degree of correlation. Therefore, in order to predict the postoperative visual acuity in eyes with media opacity and probable macular lesion, it will be necessary to combine other useful modalities.

Oscillatory potentials of local macular ERG in diabetic retinopathy

The oscillatory potentials (OPs) in electroretinogram (ERG) have clinical values in measuring retinal functions of the early stage of diabetic retinopathy.However, OPs have, until now, been evaluated as components of total ERG recorded with a full field stimulus over the entire retina. Therefore, little information could be obtained about the macular condition (diabetic retinopathy). Using focal stimuli, we successfully recorded OPs in the human macular region. We modified our previously reported system for recording local macular ERG under the fundus monitor with an infrared television fundus camera. We evaluated macular OPs with simultaneously recorded a-and b-waves in many patients with diabetic retinopathy. In some kinds of early diabetic maculopathy, the macular OPs were selectively reduced, leaving the a- and b-waves intact. The macular OPs can be a valuable indicator in assessing the macular function in diabetic maculopathy.