Abstract
Purpose :
Electroretinogram (ERG) protocols vary in test duration, from less than 10 min to more than 30 min (e.g. some research protocols). During installation, wear and removal of corneal ERG electrodes, relative motion between the electrode and the eye can cause irritation. Here we compare four measures of irritation associated with the use of two similar ERG electrodes, one made primarily of hard plastic (ERG-Jet) and one made primarily of soft silicone (RM Electrode®).
Methods :
The ERG-Jet and RM Electrode® are both contact lens corneal ERG electrodes that include integral features meant to keep the eye lids open during testing. All study participants (n=10) were healthy adults with normal vision and no recent history of corneal disease or medical procedures (e.g. LASIK). Each subject underwent baseline assessment of bulbar, limbal and tarsal redness and corneal staining (to visualize corneal abrasions) of both eyes using standard grading scales. Following administration of one drop of proparacaine HCl 0.5% in each eye, one electrode type was installed in each eye. After 20, 40 and 60 minutes of wear, during which the participant watched a video, the electrodes were removed, and eyes evaluated. Prior to reinstallation at 20 and 40 minutes, one drop of proparacaine was readministered in each eye. Corneal staining was evaluated at baseline and 60 minutes only.
Results :
Prior to ERG electrode installation, there was no difference in any measure between left and right eyes (i.e. between electrode types, paired t-test). After 20 min of wear, limbal redness was significantly higher in eyes wearing the hard electrode type (p=0.003). After 40 and 60 min of wear, limbal and bulbar redness were significantly higher in eyes wearing the hard electrode type (p<0.005 for all comparisons). At 60 min, the corneal staining was significantly higher for eyes wearing the hard electrode type (p=0.003). There was no difference in tarsal redness between eyes (electrode types) at any time point (p>0.3).
Conclusions :
For ERG testing where a corneal contact lens electrode is preferred, irritation can be reduced by using an electrode made primarily of a soft silicone. Differences in irritation were observed after 20 minutes of wear and increased with total wear time and removal/reinstallation cycles. This study included an extreme wear period of 60 total minutes which may be relevant to some extended research protocols.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.