Effect of Vertical Transposition of the Horizontal Muscles on Vertical Strabismus Associated with Exotropia

Purpose: To evaluate the correction of vertical strabismus associated with exotropia by vertical transposition of the horizontal muscle to an extent equal to half the muscle width combined with muscle recession-resection. Methods: We enrolled patients with vertical strabismus of 4-15 prism diopters (PD) associated with exotropia who were not scheduled for vertical rectus or oblique muscle surgery. Regardless of the strabismus angle, the insertion site of the horizontal muscle was vertically transposed by half the muscle width during surgery. Success was defined as a vertical strabismus angle of 2 PD or less. Results: The preoperative mean exodeviation far angle in 41 patients was 27.8 PD and the average vertical strabismus far angle 8.1 PD. The success rate of exotropia surgery was 68.3%. The mean vertical strabismus angle was 2.8 PD on postoperative day 1 and the success rate of vertical strabismus surgery 92.7%. Undercorrection was evident in 4.9% of patients and overcorrection in 2.4%. The preoperative vertical strabismus angle was strongly associated with the residual angle after surgery (r = 0.386, p = 0.013). Receiver operating curve analysis revealed that the preoperative vertical strabismus far angle cutoff was 11 PDs. No patient factor significantly influenced vertical strabismus correction. Conclusions: Vertical transposition of the horizontal muscle by half of the muscle width may correct vertical strabismus of far angle 11 PDs or less.

Types of Pattern Strabismus and Their Surgical Outcomes after Adjustable Strabismus Surgery

Purpose: To study the different types of pattern strabismus and their surgical outcomes after adjustable strabismus surgery. Study Design: Prospective, interventional study. Place and Duration of Study: Eye department, Fauji Foundation Hospital, Rawalpindi (June, 2016 to March, 2019). Methods: A total of 40 consecutive patients with pattern strabismus were included in the study. After complete orthoptic assessment, the patients underwent either rectus muscle transposition or oblique muscle surgery, by adjustable squint surgery. The pre-operative evaluation of different strabismus patterns, deviations, and post-operative results were measured and analyzed. The amount of postoperative pattern change was measured at 6 weeks postoperatively, to assess the success of the surgeries. Results: Out of 40 patients, 33 were females and 7 were males. The age ranged from 7 to 69 years (mean 18.05 ± 9.6). All patients were operated by using adjustable suture technique. “V” pattern was seen in 26 cases (65%) and “A” pattern was seen in 12 (30%) cases. The mean preoperative pattern was 13.2 ± 8.09 PD (prism diopters), and the mean postoperative pattern was 2.05 ± 2.96 PD. Surgical success was defined as the amount of pattern collapse at 6 weeks, the period at which a stable alignment was achieved. The difference between the preoperative and postoperative pattern deviation was statistically significant (p = 0.000). Correction of the pattern was seen in 92.5% of patients at average follow up of 50.87 ± 14.02 days. Conclusions: Pattern Strabismus can be corrected by varying rectus muscle transpositions or oblique muscle surgery during routine adjustable strabismus surgery. Key Words: Strabismus, V pattern, A pattern, Y pattern, X pattern, lambda pattern, muscle transposition.

The effect of strabismus surgery on choroidal thickness

Purpose: To determine the effects of strabismus surgery on choroidal thickness. Methods: This was a prospective randomized study. The measurements of subfoveal and macular choroidal thickness of patients who underwent strabismus surgery were obtained by enhanced depth imaging optic coherence tomography. The patients were grouped as patients who had 1 horizontal muscle surgery (group 1), 1 oblique muscle surgery (group 2), 2 horizontal muscle surgeries (group 3), or 1 horizontal and 1 oblique muscle surgery (group 4). Choroidal thickness of the patients was measured preoperatively and on the postoperative first day, second week, first month, and third month. Choroidal thickness was measured at subfoveal area (S) and at the nasal (N1, N2) and temporal (T1, T2) fovea with 500-μm intervals. Results: The average age of the 37 patients was 15.59 ± 13.84 years. In preoperative and postoperative first day comparison, a decrease in choroidal thickness was found in all areas in group 1. In group 2, a significant decrease was found in N2, N1, and S values. In group 3, a significant decrease was found in N2, N1, and T2 values. In group 4, a significant decrease was found in N1 value. The second week comparison of all groups showed significant postoperative decrease in choroidal thickness in all areas. On the postoperative first month, a significant decrease in choroidal thickness was found only in the subfoveal area of group 1 and the N1 area of group 2. At the postoperative third month, there was no change in any group. Conclusions: Strabismus surgery causes a decrease in choroidal thickness in the early postoperative period.