Purpose: To study the effect of orbital tumors on visual functions and highlight the factors predictive of visual outcome after surgery.
Methods: A prospective interventional study compared visual function parameters and fundus changes, before and after surgery, in eyes having well-defined orbital tumors with the normal fellow eye. These included visual acuity (VA), refractive error, keratometry changes, color vision, Goldmann visual field (GVF), and visual evoked response (VER).
Results: In total 28 cases (age range 7-56 years), of which the majority of tumors were vascular (46%) and lacrimal (18%) in origin, had a mean VA of 0.54±0.33 in the affected eye, which improved postoperatively to 0.66±0.31 (P=0.002). The affected eye had a median refractive error of +0.00 DS (-2.00 to 5.13), which was significantly more hyperopic than the normal eye (median +0.00 DS; range -1.25 to +1.63 DS) and normalized postoperatively. Keratometry showed higher astigmatism in the involved eye (P=0.004). The fundus showed disc pallor, edema, and/or choroidal folds, of which disc edema resolved in all cases after surgery. In all, 40% of the affected eyes had a deficient color vision and this partially improved postoperatively (P=0.25). GVF had abnormalities in 10 cases, half of which normalized postoperatively (P=0.04). The VER of affected eyes had a mean amplitude of 8.91±4.59 μv and latency of 116.3±14.7 ms, with improvement after surgery (P=0.005 and 0.001, respectively).
Conclusion: Orbital tumors adversely affected visual functions. The presenting acuity depended on disc changes, color vision abnormalities, and prolonged VER latency. The postoperative VA depended on VA at presentation, amount of proptosis, degree of hyperopia, and clinically significant VER abnormalities.