Interpreting Relative Afferent Pupillary Defect in Leber Hereditary Optic Neuropathy Using Interocular Visual Acuity...

Area of Science:

• Ophthalmology
• Neuro-ophthalmology
• Genetics

Background:

• Leber hereditary optic neuropathy (LHON) is a maternally inherited mitochondrial disease.
• Visual acuity asymmetry between eyes is common in LHON.
• Relative afferent pupillary defect (RAPD) is a key clinical sign in optic nerve dysfunction.

Purpose of the Study:

• To investigate the relationship between interocular visual acuity asymmetry and RAPD in LHON.
• To establish objective thresholds for the absolute interocular best-corrected visual acuity difference (|ΔBCVA|) to aid RAPD interpretation in LHON.

Main Methods:

• Retrospective analysis of genetically confirmed LHON patients presenting within 6 months of symptom onset.
• Assessment of RAPD and calculation of |ΔBCVA| (logMAR) at initial visit.
• Multivariable logistic regression and ROC analysis to determine |ΔBCVA| thresholds for RAPD prediction.

Main Results:

• |ΔBCVA| was significantly associated with RAPD in LHON patients (p<0.001).
• ROC analysis demonstrated good discrimination (AUC 0.791).
• Optimal |ΔBCVA| thresholds were identified for varying sensitivity and specificity, including 0.88 logMAR (Youden-optimal), 0.47 logMAR (high sensitivity), and 1.14 logMAR (high specificity).

Conclusions:

• RAPD in LHON is primarily driven by differences in visual acuity between the eyes.
• Quantitative |ΔBCVA| thresholds can assist in interpreting RAPD findings in LHON.
• These thresholds may help guide diagnostic work-up and follow-up for LHON patients.