Surgical Treatment of Dysthyroid Optic Neuropathy: Long-Term Visual Outcomes with Comparison of 2-Wall versus 3-Wall Orbital Decompression

Purpose: To compare the long-term visual outcomes after 2-wall (medial-lateral) versus 3-wall (medial-lateral-inferior) orbital decompression combined with fat removal in patients with dysthyroid optic neuropathy (DON). Methods: Records of 68 eyes of 42 patients were retrospectively reviewed. Two-and 3-wall decompression was performed in 41 and 27 eyes, respectively. Transcaruncular approach was used for medial wall decompression. Lateral canthotomy combined with upper eyelid crease incision was used for lateral wall removal, and combined with transconjunctival lower eyelid incision if floor decompression performed. Outcome measures were visual acuity (VA), color vision, Hertel measures, visual field mean deviation (MD) and pattern standard deviation (PSD) Result: The mean follow-up time was 39.3 months (range, 12-72 months). All indicators of visual function significantly improved after 2-and 3-wall decompression. The improvement in VA and color vision was similar between groups. (logMAR VA: 2-wall: 0.52 +/- 0.68 versus 3-wall: 0.71 +/- 0.86, p = 0.335); (color vision on Ishihara plates: 2-wall: 10.1 +/- 8.1 versus 3-wall: 11.6 +/- 7.8, p = 0.447). The improvement in MD and PSD were higher after 3-wall decompression (MD: 2-wall: 10.0 +/- 5.5 versus 3-wall: 14.3 +/- 7.5 dB, p = 0.020); (PSD: 2-wall: 3.5 +/- 1.9 versus 3-wall: 4.8 +/- 3.0 dB, p = 0.045). Proptosis reduction was higher after 3-wall decompression (2-wall: 5.1 +/- 1.3 versus 3-wall: 7.2 +/- 1.9 mm, p = 0.0001). New onset diplopia was seen 20% and 28.5% of cases in 2-and 3-wall decompression, respectively. No adnexal/orbital complications were seen in 2-wall group, however orbital hematoma (1 case) and persisting eyelid edema (1 case) were encountered in 3-wall group. Conclusion: Both 2-and 3-wall orbital decompressions are safe and effective for management of visual dysfunction in DON. Although 3-wall decompression provide better improvement in the parameters of visual field analysis and Hertel measures, new onset diplopia, adnexal/orbital complications are more common with this technique.