Evaluating the interreader agreement and intrareader reproducibility of Visual Field Defects in Thyroid Eye Disease– Compressive Optic Neuropathy

PURPOSE: To categorize visual field (VF) defects according to Freitag and Tanking’s (FT) classification in Thyroid Eye Disease-Compressive Optic Neuropathy (TED-CON) and evaluate the interreader agreement and intrareader reproducibility of the classification. SUBJECTS AND METHODS: In this retrospective, observational study we included medical reports of 96 eyes (51 patients), who underwent VF testing with TED-CON in Ludwig-Maximilians-University (2008–2019). Two readers separately examined the VFs at the time of the TED-CON diagnosis, each offering two readings of the same VF in a time interval of 1 month. None of our patients were diagnosed with only VF testing. The visual field testing was only performed when the inclusion criteria for TED-CON were met. RESULTS: The most common VF defects upon TED-CON diagnosis were stage 1b defects in FT classification (34.4% for reader 1, 35.4% for reader 2), followed by stage 2b (10.4% for reader 1, 14.6% for reader 2), and stage 3 (10.4% for both readers). The overall interreader agreement between 2 examiners was substantial for the first reading (69.8% agreement, kappa 0.635 (95% CI [0.525–0.745])) and moderate for the second reading (66.7% agreement, kappa 0.598 (95% CI [0.488–0.708])). The intrareader reproducibility ranged from substantial to almost perfect (78.1% agreement) between readings (kappa 0.736 (95%CI [0.638–0.834])) for reader 1 and 90.6% agreement (kappa 0.885 (95%CI [0.814–0.956])) for reader 2. CONCLUSION: We found good BCVA (LogMAR ≤ 0.2), in nearly half of the cases (44 eyes, 45.8%) and also, strikingly near perfect visual acuity (BCVA LogMAR ≤0.1) in 22.9% of the cases (22 eyes) with TED-CON. We conclude that clinicians should be alert to VF defects in the inferior region (stage 1a/1b in the FT classification) even in patients with a good BCVA.