Levator muscle resection for simple congenital ptosis: its impact on preoperative levator function and dose-response ratio.

OBJECTIVE: The primary aim of this study is to calculate the dose-response ratio in patients with different levels of levator function following levator resection in simple congenital ptosis. The secondary outcome is to evaluate the success rate and effect of levator resection on postoperative levator function. METHODS: In a retrospective study, the medical records of patients were reviewed for age, gender, laterality, preoperative and postoperative measurements (palpebral fissure height, marginal reflex distance 1, and levator function), magnitude of levator resection, follow-up time, and postoperative complications. RESULTS: Of 154 patients with a mean age of 17.12 ± 11.14 years, 54 patients had excellent levator function, 41 had good function, and 59 had fair function. Following surgery, the mean levator function increased from 8.81 ± 3.40 mm to 11.29 ± 3.25 mm. The magnitude of increase in the 3 groups of excellent, good, and fair was 3.18 ± 2.63, 2.53 ± 2.24 and 1.92 ± 1.80 mm, respectively. The rate of success was 81.8% with no statistically significant difference in the 3 groups. In a multivariate logistic regression, older age, local anaesthesia, and milder ptosis were predictors of success. A table of dose-response ratios was calculated that determined the amounts of levator muscle resection for 1 mm of marginal reflex distance 1 and levator function increase. CONCLUSIONS: Levator resection has high success rate in patients with simple congenital ptosis. The function of levator muscle improved significantly following surgery, and the rate of improvement was higher in patients with better preoperative levator function.

The impact of simulated hemianopia on visual search for faces, words, and cars.

Tests of visual search can index the effects of perceptual load and compare the processing efficiency for different object types, particularly when one examines the set-size effect, the increase in search time for each additional stimulus in an array. Previous studies have shown that the set-size effect is increased by manoeuvres that impede object processing, and in patients with object processing impairments. In this study, we examine how the low-level visual impairment of hemianopia affects visual search for complex objects, using a virtual paradigm. Forty-two healthy subjects performed visual search for faces, words, or cars with full-viewing as well as gaze-contingent simulations of complete left or right hemianopia. Simulated hemianopia lowered accuracy and discriminative power and increased response times and set-size effects, similarly for faces, words and cars. A comparison of set-size effects between target absent and target present trials did not show a difference between full-view and simulated hemianopic conditions, and a model of decision-making suggested that simulated hemianopia reduced the rate of accumulation of perceptual data, but did not change decision thresholds. We conclude that simulated hemianopia reduces the efficiency of visual search for complex objects, and that such impairment should be considered when interpreting results from high-level object processing deficits.

Outcomes of Bilateral Lateral Rectus Resection in Residual Esotropia following Bilateral Medial Rectus Recession.

Purpose: To evaluate the success rate, dose-response ratio, and predictive factors of success in patients with residual esotropia (≥25 prism diopter [pd]) following bilateral medial rectus (BMR) recession who underwent bilateral lateral rectus (BLR) resection. Methods: In a retrospective study, medical records were reviewed for 47 patients with equal or more than 25 pd residual esotropia following 6 mm BMR recession. Sex, age at second surgery, the interval between first and second surgery in months, visual acuity, refraction, presence of amblyopia, presence of dissociated vertical deviation or inferior oblique overaction/superior oblique overaction, preoperative and postoperative angle of deviation, amount of BLR resection, and months of follow-up were evaluated. Surgical success was defined as postoperative deviation within 8 pd of orthophoria. Results: The mean age of patients at reoperation was 48.59 ± 21.46 months. The mean near and far residual esotropia before BLR resection was 34.57 ± 11.02 and 33.83 ± 10.99 pd, respectively, reduced to 8.12 ± 1.43 pd in near and 6.32 ± 2.1 pd in far postoperatively. The mean BLR resection dosage was 5.53 ± 1.22 mm and each millimeter of BLR resection (1 mm for each eye) corrected an average of 7.95 pd of deviation in near and 7.40 pd in far. The success rate was 74.5%. After analysis using multivariate logistic regression, there were no factors associated with success. Conclusions: Bilateral rectus resection in patients with a previous BMR recession has acceptable outcomes. The recommended surgical table can be used as a guide by strabismus surgeons in patients with residual esotropia.

Outcomes and Dose-Response Ratio of Surgery on Three Muscles in Large-Angle Exotropia.

PURPOSE: To evaluate the efficacy of three-muscle surgery for the treatment of large-angle exotropia with particular attention to the success rate and mean dose-response ratio. METHODS: In a retrospective study, medical records were reviewed for 48 patients with exodeviation between 50 and 80 prism diopter (PD) who underwent bilateral lateral rectus recession as well as one medial rectus resection. Sex, age at surgery, presence of amblyopia, amount of preoperative and postoperative deviation, total amount of recessed and resected muscles, dose-response ratio, and associated vertical deviations were analyzed. RESULTS: The mean age of patients at surgery was 25.4 ± 14.3 years old (range, 1-55). The mean preoperative deviation was measured 62.8 ± 7.5 PD (range, 50-80 PD). The mean amount of total recession and resection was 23 ± 1.3 mm. After a mean follow-up of 15 ± 25 months (range, 3-144), 85.4% of patients were within 10 PD of orthophoria. The mean postoperative deviation decreased to 3.8 ± 7.5 PD (range, 0-30 PD). A mean dose-response ratio of 2.5 ± 0.3 PD/mm (range, 0.9-3.1 PD/mm) was found. Of all patients, 14.6% demonstrated undercorrection. CONCLUSION: Simultaneous surgery on three muscles is an effective method in resolving large-angle exotropia and results in excellent outcomes with low risk of undercorrection.

Outcomes of symmetric bilateral medial rectus recession in large-angle esotropic Duane syndrome.

PURPOSE: To evaluate the efficacy of symmetric bilateral medial rectus recession in large-angle esotropic Duane retraction syndrome (DRS) with moderate to severe globe retraction. METHODS: In a retrospective study, medical reports of 30 patients with esotropia of equal or more than 20 prism diopters (pd) and moderate to serve globe retraction due to unilateral DRS who underwent symmetric bilateral medial rectus recession were reviewed. Age, gender, laterality, amblyopia, length of follow-up, pre- and postoperative measurements of primary position deviation, ocular ductions and severity of globe retraction and abnormal head posture were evaluated. A successful result was defined as decreasing esotropia to equal or less than 8 pd or equal or less than 8 pd of consecutive exotropia. RESULTS: The mean age of patients at surgery was 13.7 ± 8.5 years old (range: 3-38). The mean preoperative esotropia measured 28.9 ± 9.1 pd in distance and 25.7 ± 7.2 pd in near, which decreased to 4.9 ± 6.1 pd in distance and 3.9 ± 8.8 pd in near postoperatively. The mean bilateral medial rectus recession was 4.9 ± 0.9 mm (range: 3-6 mm). The mean abnormal head posture improved from 19.1 ± 6.9 degrees (range: 10-30 degrees) to 3.3 ± 4.7 degrees (range: 0-15 degrees) postoperatively. At the last follow-up visit, 23 patients (76.7%) had a successful outcome. CONCLUSIONS: In the large-angle esotropic DRS patients with moderate to severe globe retraction, symmetric bilateral medial rectus recession, can be conducted to successfully resolve primary position deviation and abnormal head posture.

Efficacy of isolated inferior oblique anteriorization on large-angle hypertropia associated with unilateral superior oblique palsy.

PURPOSE: To evaluate the results of inferior oblique anteriorization for the treatment of large-angle hypertropia secondary to superior oblique palsy and to determine predictors of success and the occurrence of antielevation syndrome. METHODS: In this prospective study, 25 patients with unilateral congenital and acquired superior oblique palsy who had a primary position hypertropia of at least 25Δ underwent inferior oblique anteriorization in the paretic eye. Postoperative changes in vertical deviation of primary position and contralateral gaze, abnormal head posture, extorsion, associated horizontal deviation, inferior oblique overaction, superior oblique underaction, and elevation in abduction were examined. Surgical success was defined as residual hypertropia in primary position of ≤4Δ at final examination. RESULTS: The mean age of patients at surgery was 19.8 ± 11.9 years (range, 4-49). The mean preoperative deviation in the primary position was 27.6Δ ± 3.2Δ; in contralateral gaze, 35.0Δ ± 3.8Δ; these measurements decreased postoperatively to 4.7Δ ± 5.6Δ and 7.0Δ ± 5.5Δ, respectively, after a median follow-up of 8 months. The success rate was 72%, with no difference between patients with a preoperative deviation of 25Δ-29Δ and those with deviation of 30Δ-35Δ. In a multivariate logistic regression, preoperative extorsion was negatively related to success (OR = 8.01; P = 0.03). At the final follow-up, 4 patients (16%) showed antielevation syndrome and were clinically asymptomatic. CONCLUSIONS: In unilateral superior oblique palsy, one-muscle surgery, including inferior oblique anteriorization, can be conducted to resolve large-angle hypertropia of >25Δ. Excyotorsion is a risk factor that increases the likelihood of failure.

Three horizontal muscle surgery for large-angle esotropia: success rate and dose-effect ratio.

AIM: To evaluate the moderate-term success and calculate the mean dose-effect ratio in large-angle esotropic patients who underwent three muscle surgery. METHODS: In a retrospective study, we reviewed the medical records of 37 patients with large-angle esotropia who underwent bilateral medial rectus recession and one lateral rectus resection. Sex, age at surgery time, amount of recessed or resected muscles in millimeter (mm), pre- and postoperative alignment in prism diopter (D), dose/response ratio, and presence of amblyopia and other associated vertical deviations were recorded. RESULTS: The mean age of subjects at surgery was 12.2±12.3y (range: 1-57). The mean preoperative deviation of 70.4±8.1 D (range: 60-85 D) decreased to a mean of 5.4±8.1 D (range: 0-30 D) postoperatively (P<0.005). Successful alignment was achieved in 30 of 37 patients (81%) at a mean follow-up of 15.7±20.1mo (range: 3-90). The mean amount of recession and resection was 17.59±1.29 mm, and a mean dose-response ratio of 3.79±81 (range: 2.83-4.66) was determined. CONCLUSION: Three-muscle surgery for large-angle esotropia results in good moderate-term outcomes without high rates of overcorrection or undercorrection.

Surgical treatment of Duane retraction syndrome.

PURPOSE: Surgical treatment in Duane retraction syndrome (DRS) can be very challenging even for the strabismus specialists because of a wide spectrum of diversity in clinical manifestations. The purpose of this article is to review these different surgical treatments. METHODS: A comprehensive search was performed using PubMed database with the different keywords of "Duane retraction syndrome" and "surgery". Articles were selected from original English papers published since 2000. The full text of the selected articles was reviewed, and some articles were added based upon the references of the initial articles. We also provided selected case examples about some of these procedures. RESULTS: 125 articles were found in the initial search of which 37 articles were mostly related to the topic of this review. The number finally increased to 59 articles after considering the relative references of the initial articles. Different surgical methods performed on horizontal and vertical rectus muscles (recession, resection, transposition, Y splitting, periosteal fixation and posterior fixation suture) are reviewed. Careful selection of the surgical technique is important to achieve optimal results. CONCLUSION: With accurate diagnosis of patients with DRS and proper surgical management, several adverse situations associated with this syndrome (amblyopia, abnormal head posture, upshoot, downshoot, and muscle underaction) can be prevented.