A literature search was last conducted on October 22, 2019 and updated on April 8, 2020 in the PubMed database for English-language original research that assessed the effect of various interventions for indirect TON. One-hundred and seventy-two articles were identified; 41 met the inclusion criteria outlined for assessment and were selected for full-text review and abstraction. On full-text review, a total of 32 studies met all of the study criteria, and were included in the analysis.
No study met criteria for level I evidence. Seven studies (1 level II study, 6 level III studies) explored corticosteroid therapy that did not have uniformly better outcomes than observation. Twenty (3 level II study, 17 level III studies) assessed optic canal decompression and the use of corticosteroids. Even though visual improvement was noted after decompression, studies that directly compared surgery with medical therapy did not report uniformly improved outcomes after decompression. Four studies (1 level II study, 3 level III studies) evaluated the use of erythropoietin. Although initial studies demonstrated benefit, a direct comparison of its use with observation and corticosteroids failed to confirm the utility of this medication. One study (level II) documented visual improvement with levodopa-carbidopa. Complication rates were variable with all of these interventions. Pharmacologic interventions were generally associated with few complications, whereas optical canal decompression carried risks of serious side effects, including hemorrhages and cerebrospinal fluid leakage.
Despite reports of visual improvement with corticosteroids, optic canal decompression, and medical therapy for indirect TON, the weight of published evidence does not demonstrate a consistent benefit for any of these interventions. In summary, there is no consensus from studies published to date on a preferred treatment for TON. Treatment strategies should be customized for each individual patient. More definitive treatment trials will be needed to identify optimal treatment strategies for indirect TON.
Copyright © 2020. Published by Elsevier Inc.