Abstract
PurposeTo 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 methodsIn 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.ResultsThe 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.ConclusionWe 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.
Highlights
In 1786, Caleb Perry became the first to describe an association between proptosis and hyperthyroidism
By comparing categorizations produced by two independent examiners, as well as those produced by the same examiner over multiple readings, we offer the evaluation of interreader agreement and intrareader reproducibility of the Freitag and Tanking (FT) classification
The results show the distribution of best-corrected visual acuity (BCVA) within each stage to be similar across the two readers for all stages except the scatter defects where the cases classified into this stage by reader 1 (LR) have a wider distribution of BCVA compared to those put into this stage by reader 2 (AGK)
Summary
In 1786, Caleb Perry became the first to describe an association between proptosis and hyperthyroidism. In many cases, diagnosing CON requires additional examinations such as tests for colour vision or visual field (VF), orbital imaging, pattern electroretinogram, and/ or visual-evoked potentials, some of which depend strongly on the patient’s cooperation. Even with these examinations at hand, diagnosis can be difficult due to multifactorial causes underlying visual loss. A recent article by Freitag and Tanking (FT hereafter) makes an important contribution by offering the first classification scheme for the visual field (VF) defects in progressive TED-CON This classification, if proven reliable, promises to help clinicians in detecting the early signs of VF changes, and in categorizing the progression of the defects and monitoring their treatment [5]
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