A series of 57 diabetics underwent standard electroretinographic recordings for the purpose of testing the effect of insulin on the electroretinograms in diabetes mellitus, specifically on the oscillatory potential changes (Kozak et al., Jap. J. Ophthal. Suppl., 1979). Use of the speculum-type corneal electrode (Burian-Allen, Hansen Labs.,) produced 9 corneal abrasions in the first 28 patients in this series. However, when the technique of examination was altered by use of the Henkes-type bipolar electrode, only 2 abrasions were produced in the last 29 patients. These frequencies of abrasions are statistically different. The suggestion is made that electroretinographic tracings in diabetics the performed with the use of the Henkes bipolar low-vacuum corneal electrode (Medical Workshops, Holland).
Recent investigations in this laboratory of the effect of insulin on the electroretinogram of diabetic patients (1) revealed different frequencies of inadvertent corneal abrasions with two types of contact lens electrodes, ie. the Burian-Allen (2) and the Henkes (3) types. Biomicroscopy employing fluorescein stained tears with cobalt blue filter was used to examine the corneas of each eye tested following electroretinographic tracings.Every subject was dark-adapted for 30 to 60 minutes prior to the ERG examination and each tested eye was dilated with Tropicamide 0.5.%. Two drops of the ophthalmic anesthetic, Proparacaine hydrochloride 0.5.%, were instilled on the corneal surface prior to placement of the electrode on the cornea. Methylcellulose 0.5.% was used in all patients for moistening and lubricating effect with the Burian-Allen (2) speculum-type electrode as advocated by the developers; and this contact lens was used initially as it has been successful for routine ERG work in the past. Though Burian and Allen reported 'thousands' of ERG's obtained with the use of their speculum electrode in both normal and clinical subjects, they reported no special effect on the corneas in diabetics in their series. However, routine testing is completed in several minutes, considerably shorter than in the experimental study.In the first 19 patients, Burian-Allen electrode (Hansen Laboratories, Iowa City) with the intact transparent plastic corneal speculum (8.5 mm inner radius of curvature) was used. Five (26%) of these patients revealed localized loss of corneal epithelim on biomicroscopy with fluorescein. In order to reduce the risk of a misfit between the curvature of the speculum and that of the cornea and to improve corneal tissue respiration, we subsequently tested 9 patients by means of a modified corneal electrode in which a 5 mm diameter hole was drilled centrally in the corneal speculum (modified and manufactured by Mr. Hansen). Four of these patients (44%) developed localized loss of corneal epithelium. Both the original and modified Burian-Allen electrodes were thoroughly cleansed before each examination using an ultrasound 333
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.