The Therapeutic Effect of Combination of Orbital Decompression Surgery and Methylprednisolone Pulse Therapy on Patients with Bilateral Dysthyroid Optic Neuropathy

Purpose. To investigate the synergic effect of combination of orbital decompression surgery and methylprednisolone pulse therapy (MPT) and MPT alone on the visual function in patients with bilateral dysthyroid optic neuropathy (DON). Methods. For each involved patient with bilateral DON, only one eye was treated with orbital decompression surgery which was conducted by the same doctor, and each of them received MPT after surgery. If the visual function deteriorated despite treatment, patients would switch to the other treatment. All the patients were followed up for 3 months after surgery. Clinical features of patients including best corrected visual acuity (BCVA), intraocular pressure (IOP), proptosis, upper eyelid retraction, and clinical activity score (CAS) before and after surgery were analyzed, respectively. Visual field and visual evoked potential (VEP) tests were also performed. Paired t-test and Wilcoxon matched-pairs signed ranks sum test were used to analyze the data. Result. A prospective cohort of 23 patients with bilateral DON was enrolled in this cohort study. No patients failed to the therapy or switched to another treatment. The quantitative variables were shown as means and standard deviations (SD). After 3 months of combined treatment of orbital decompression surgery and MPT, BCVA (logMAR) improved, proptosis was reduced and the upper eyelid retraction was relieved in both eyes of patients; however, these improvements were more significant in the operated eyes than in the fellow (nonoperated) eyes. IOP decreased significantly in the operated eyes (P=0.002), while having no significant change in the nonoperated eyes (P=0.993). CAS reduced by 0.8 ± 1.37 in the operated eyes and by 0.9 ± 1.28 in the nonoperated eyes (P=0.011, P=0.005, respectively), but its reduction extent showed no significant difference between the operated and fellow eyes (P=0.771). Visual field tests showed the mean deviation (MD) of the operated and fellow eyes both increased significantly after 3 months of treatment (P<0.001, P=0.001, respectively). MD of the operated eyes increased by 8.1 ± 7.72 dB, which was more significant than that of the fellow eyes which increased by 3.4 ± 5.02 dB (P=0.005). The VEP test showed that, in the operated eyes, the latency of each spatial frequency of P100 was significantly shortened (P<0.05, respectively), and the amplitude was significantly improved (P<0.05, respectively); however, there was no significant change in VEP parameters of the fellow eyes (P>0.05, respectively). The latency in the operated eyes improved by 28.1 ± 29.93 ms in 60′ P100, by 40.2 ± 32.87 ms in 30′ P100, and by 20.7 ± 25.87 ms in 15′ P100 respectively, which was more excellent in the degree of the improvement than that in the fellow eyes (P=0.002, P=0.001, P=0.005, respectively). Conclusion. A combination of orbital decompression and MPT can significantly improve visual function in patients with DON, reduce intraocular pressure, and relieve clinical symptoms such as upper eyelid retraction and proptosis, while MPT alone has a limited effect. For DON patients, orbital decompression should be performed promptly to improve the visual function.