Abstract
Purpose :
The American Academy of Ophthalmology recommends yearly ophthalmologic screenings for patients on hydroxychloroquine (HCQ) to prevent the development of HCQ-induced retinal toxicity. An important tool for this screening is multifocal electroretinography (mfERG) using amplitude ring ratios (RR). This study explored the effect of repeat mfERG testing within the same session on RR in patients with initially poor mfERG signals.
Methods :
A chart/data review of patients who underwent repeat mfERG testing within 5 minutes of the first test was performed. Recordings were performed binocularly (Espion mfERG system, Diagnosys LLC, Lowell, MA) with fiber electrodes and a standard protocol with 61 hexagonal elements (grouped in 5 rings), 60 degrees width of stimulus and 420 cd/m2 maximal brightness. P1 amplitudes were extracted and used to calculate three clinically relevant RR: ring 1 to ring 2 (R1/R2), ring 5 to ring 4 (R5/R4), and ring 5 to ring 3 (R5/R3). A paired t-test was used to compare values from run 1 and run 2. Ratios were categorized as either normal (below the upper limit of the normal range, within 3 standard deviations above the mean) or abnormal (above the upper limit of normal range). Changes in normality were recorded.
Results :
Records from 35 patients (2 M, 33 F, average age 55.6 ± 18.1 yrs) were analyzed. There was no significant difference between run 1 and run 2 for mean R5/R4 or mean R5/R3 (p>0.05), but mean R1/R2 decreased significantly from 2.45 to 1.94 in right eyes (RE) (p<0.05) and from 2.35 to 1.79 in left eyes (LE) (p<0.05). Several initially abnormal R1/R2 became normal on run 2 (11 out of 18 or 61% RE; 11 out of 14, or 79% LE). In some cases (2 RE and 4 LE), an initially normal R1/R2 became abnormal. Several initially abnormal R5/R3 also became normal on run 2 (2 out 3 or 66% RE; 3 out of 5, or 60% LE), and some initially normal R5/R3 became abnormal (3 RE, 0 LE). For R5/R4, several initially abnormal ratios became normal (4/5 or 80% RE, 7/8 or 88% LE), and some initially normal ratios became abnormal (4 RE, 2 LE).
Conclusions :
Repeat mfERG testing is sometimes used for patients receiving HCQ screening with poor initial tests. This study showed a significant decrease in R1/R2 from the first to second run at a group level and changes in a sizable proportion of patients who screened positive based on R1/R2, R5/R3, and R5/R4.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.