Quantitative assessment of the 103-hexagon multifocal electroretinogram in detection of hydroxychloroquine retinal toxicity.
OBJECTIVE
To evaluate the utility of ring ratios in detecting hydroxychloroquine (HCQ) related retinal toxicity using the 103-hexagon multifocal electroretinogram (mfERG).


METHODS
Retrospective cross-sectional study.


METHODS
23 patients taking HCQ were consecutively evaluated for retinal toxicity and divided into those without (HCQ-non-toxic group) and with documented visual field loss (HCQ-toxic group). A control patient group without retinal disease and not on HCQ was used for comparison. 103-hexagon P(1) mfERG amplitude response densities were analysed by averaging the 103 responses into six (age-corrected) concentric rings (R(1)-R(6)), calculating standard ring ratios (R(1):R(2)-R(1):R(6)) and R(5) ring ratios (R(5):R(1)-R(5):R(6)). Receiver operating characteristic curves were used to compare these tests for detecting toxicity.


RESULTS
Relative to HCQ-non-toxic and control groups, the HCQ-toxic group showed generalised reduction of the 103-hexagon mfERG absolute responses most prominent in the foveal/pericentral regions. R(5) ring ratios were superior to standard ring ratios in discriminating the HCQ-toxic from the HCQ-non-toxic and control groups and were approximately equivalent to pericentral absolute ring responses in detecting HCQ retinal toxicity by receiver operating characteristic criteria, with R(5):R(4) and R(5):R(3) ratios performing best. However, R(5) ring ratios revealed improved sensitivity over absolute ring responses (89% vs 73%) at a 95% specificity threshold.


CONCLUSIONS
Ring ratio analysis using the R(5) ring response as the 'internal reference ring' appeared equivalent to pericentral absolute ring responses in detecting HCQ retinal toxicity, and possibly superior at clinically desirable specificity thresholds. R(5) ring ratios did not require age correction, a potential clinical advantage over absolute ring responses.
The Department of Ophthalmology, Medical College of Wisconsin, 925&emsp14;N. 87th St, Milwaukee WI 53226, USA.
Murtaza K
MK
Adam
Douglas J
DJ
Covert
Kimberly E
KE
Stepien
Dennis P
DP
Han
D000293:Adolescent; D000328:Adult; D000368:Aged; D018501:Antirheumatic Agents / Q000009:adverse effects*; D019540:Area Under Curve; D002648:Child; D003430:Cross-Sectional Studies; D004596:Electroretinography / Q000187:drug effects*; D005260:Female; D006801:Humans; D006886:Hydroxychloroquine / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D012160:Retina / Q000187:drug effects / Q000473:pathology*; D012164:Retinal Diseases / Q000139:chemically induced / Q000175:diagnosis*; D012189:Retrospective Studies; D014794:Visual Fields
D018501:Antirheumatic Agents; D006886:Hydroxychloroquine