Strabismus after deep lateral wall orbital decompression in thyroid-related orbitopathy patients using automated Hess screen

Purpose: To evaluate the effect of deep lateral wall orbital decompression with intraconal fat debulking on strabismus in thyroid-related orbitopathy (TRO) patients using automated Hess screen (AHS). Design: Prospective nonrandomized clinical study. Participants: Eleven TRO patients (19 surgeries) operated on at the Jules Stein Eye Institute from January, 2004, through December, 2004. Methods: Automated Hess screen testing was performed in all patients before surgery and 3 months after surgery; all patients received surgery in the nonactive phase of the disease. Main Outcome Measures: Amplitude of horizontal and vertical deviations (prism diopters) in all standard positions of gaze. Results: Eleven TRO patients (7 females; mean age, 47 years) were included in the study; 8 patients underwent bilateral surgery. After surgery, exophthalmos decreased an average ( +/- standard deviation) of 2.7 mm ( +/- 2.5 mm; P = 0.003). Before surgery, 7 patients (63%) reported primary gaze diplopia, whereas only 2 patients (18%) showed diplopia in primary gaze after surgery (P = 0.03, chi-square analysis). Orbital decompression had no statistically significant effect on horizontal and vertical ocular deviations measured by AHS. Mean amplitude of deviation in primary gaze was 1.2 prism diopters (PD) esotropia and 0.07 PD hypotropia before surgery, and 2.5 PD exotropia with 0.6 PD hypertropia after surgery (delta = 3.7 PD for horizontal deviation and -0.7 for vertical deviation; P = 0.051, paired samples t test for horizontal difference and P not significant for vertical difference). Nonsignificant P values were obtained in all 9 positions of gaze. Most patients had periocular numbness that resolved spontaneously 2 to 6 months after surgery. Conclusions: Deep lateral wall orbital decompression with intraconal fat debulking had no statistically significant effect on horizontal and vertical deviations measured by the AHS. Patients may demonstrate small angle exotropia shift, but this finding was not clinically significant.