BACKGROUND

Dysthyroid optic neuropathy (DON) is a serious threatening vision loss in Graves' ophthalmopathy (GO). Although the European Group on Graves' Ophthalmopathy (EUGOGO) recommend intravenous methylprednisolone therapy for first line treatment, some characteristics predicting the response are still inconclusive.

AIM

To study the efficacy of intravenous pulse methylprednisolone (IVMP) in treating dysthyroid optic neuropathy (DON) and to identify factors predicting poor response to the treatment.

METHODS

All patients diagnosed with DON between January 2010 and December 2021 at Rajavithi Hospital, Thailand, receiving IVMP 1 g/ day for 3 consecutive days were analyzed. The efficacy at 1 week and 3, 6, 12-months in terms of improvement of best corrected visual acuity (BCVA) and proptosis were compiled.

RESULTS

Of the entire 57 DON cases that received IVMP, 50.9% gained at least 0.2 Logarithm of the Minimum Angle of Resolution (logMAR) at 1 week, and the improvement from initial to 1-week BCVA was 0.63 ± 0.63 logMAR (p < 0.001) and the decrease in proptosis was 1.8 ± 1.36 mm (p < 0.001). The remaining 23 orbits underwent orbital decompression and were excluded from the long-term efficacy analysis. In the last 12-months' follow-up time, there was an improvement of BCVA (0.53 ± 0.47 logMAR) and proptosis (0.59 ± 0.66 mm) (both p < 0.001). At last visit, there was an improvement of BCVA (0.2 logMAR) and proptosis (2 mm) in 76.5, and 5.9% respectively. Significant predictive factors of poor treatment response were age ≥ 55 years (odds ratio [OR]: 8.28, 95% confidence interval [CI]: 1.368-50.121, p = 0.021); longer onset duration before treatment (OR: 5.10, 95%CI: 1.061-24.501, p = 0.042); and proptosis at baseline (OR: 9.31, 95%CI: 1.872-46.280, p = 0.006). The strongest risk factor for predicting poor response to IVMP was poor initial visual acuity (OR: 10.26, 95%CI: 1.363-77.234, p = 0.024).

CONCLUSIONS

IVMP is effective for both short- and long-term treatment to improve visual acuity greater than proptosis. Older age, longer disease duration, poor initial visual acuity, and proptotic orbits were identified as risk factors for predicting poor response to IVMP treatment in Thai population. DON patients having those risk factors should be suspected, and treated early with IVMP to preserve their future vision.