Abstract
Purpose
Orbital inflammatory diseases (OID), including Graves’ ophthalmopathy (GO), orbital pseudotumor (OP), and IgG4-related ophthalmic disease (IgG4-ROD), often require prolonged corticosteroid therapy, which may lead to severe hormonal side effects. These diseases are notably refractory and resistant to corticosteroids. While opposing lateral-field radiotherapy has shown positive results, the potential of volumetric-modulated arc therapy (VMAT) to enhance efficacy and reduce side effects remains uncertain. This study evaluates the radiation dose, clinical efficacy, side effects, and outcomes of orbital VMAT in patients with refractory, corticosteroid-resistant OID.
Methods and materials:
A retrospective analysis was conducted on 58 patients with refractory, corticosteroid-resistant OID treated with orbital VMAT from November 2019 to July 2022. The primary endpoint was the reduction or cessation of corticosteroid use following radiotherapy, with secondary endpoints including improvements in ocular clinical symptoms (diplopia, proptosis, visual acuity, and extraocular movement) and long-term side effects.
Results
The median target dose was 20 Gy, with an average lens irradiation dose of 5.4 Gy. Initially, all 58 patients received corticosteroids. After a median follow-up of 27.5 months, 89.7% (52/58) of patients responded positively to radiotherapy: specifically, 55.2% (32/58) completely tapered off corticosteroids, while 34.5% (20/58) reduced their dosage. Symptomatic improvements were observed in diplopia (66.0%), proptosis (63.5%), visual acuity (55.2%), and extraocular movements (66.7%). Regarding the long-term side effects of radiotherapy, incidences of dry eye syndrome and lens opacities were reported at 3.4% and 1.7%, respectively.
Conclusions
Orbital VMAT is an effective treatment for refractory, corticosteroid-resistant OID, reducing corticosteroid use and improving ocular symptoms with minimal side effects. Further prospective clinical trials are warranted to validate more appropriate VMAT doses and planning models, enhancing treatment outcomes without increasing radiotherapy side effects.