Time and Factors Affecting the Direction of Re-drift in Essential Infantile Esotropia.

PURPOSE: To investigate the development pattern and related factors of postoperative re-drift in infantile esotropia. METHODS: A total of 112 patients with infantile esotropia who underwent surgery before 3 years of age were included. Surgical outcomes were divided into (1) consecutive exotropia: more than 8 prism diopters (PD) of exodeviation; (2) recurrent esotropia: more than 8 PD of esodeviation; and (3) monofixation syndrome: maintenance of deviations within 8 PD. The occurrence rate, time of onset, and associated factors of the re-drift were evaluated. RESULTS: At a mean follow-up of 9.5 years, consecutive exotropia developed in 37 patients (33.0%) and recurrent esotropia in 43 patients (38.4%). Whereas 76.7% of total recurrent esotropia cases were identified within postoperative 1 year, consecutive exotropia occurred constantly over 10 years postoperatively. The mean time to consecutive exotropia development from surgery was 78.6 months, greater than that of recurrent esotropia development (8.9 months) (P < 0.001). In multinomial logistic regression using monofixation syndrome as the reference category, fixation preference before surgery (odds ratio [OR]: 6.64, 95% confidence interval [CI]: 2.07 to 21.32) and the rate of myopic progression (OR: 15.07 per -1.00 D/year, 95% CI: 1.23 to 184.86) were associated with consecutive exotropia, whereas increase in the angle of esodeviation on postoperative day 1 (OR: 1.15, 95% CI: 1.04 to 1.26) was correlated with recurrent esotropia. CONCLUSIONS: This study demonstrates a difference between the development pattern of exotropic and esotropic drift after infantile esotropia surgery. Detailed preoperative assessment and close postoperative observation of deviations and refractive status will help to determine surgical outcomes of infantile esotropia. [J Pediatr Ophthalmol Strabismus. 2018;55(2):128-134.].

Clinical exhibition of increased accommodative loads for binocular fusion in patients with basic intermittent exotropia.

BACKGROUND: To investigate the accommodative loads change needed to maintain binocular fusion in patients with intermittent exotropia (IXT). METHODS: Seventeen consecutive patients with basic IXT and 15 normal controls were recruited. The WAM-5500 autorefractor (GrandSeiko, Fukuyama, Japan) was used to measure refractive error (D) under binocular and monocular viewing conditions at 6 m, 50 cm, 33 cm and 20 cm. The difference between binocular and monocular refractive error (D) at each distance defined the change in the accommodative load. The changes in accommodative load were compared between IXT patients and normal controls. We also investigated the change in accommodative loads according to the fixing preference in patients with IXT. RESULTS: In IXT patients, the mean angles of deviation were 20.2 ± 7.19 and 21.0 ± 8.02 prism diopters at 6 m and 33 cm, respectively. Under binocular viewing, the changes in accommodative loads of each eye in IXT patients were significantly higher at 50, 33 and 20 cm than those of normal controls (p < 0.05, all). The changes in accommodative loads of fixating and deviating eyes at 6 m were not significantly different between IXT patients and normal controls (p = 0.193, 0.155, respectively). The changes in accommodative loads of the fixating eye at each distance were not significantly different from those of the deviating eye in IXT patients (p > 0.05). CONCLUSION: The changes of accommodative loads at near fixation increased more in IXT patients than they did in normal controls while maintaining binocular fusion.

Effect of watching 3-dimensional television on refractive error in children.

PURPOSE: To investigate the effect of watching 3-dimensional (3D) television (TV) on refractive error in children. METHODS: Sixty healthy volunteers, aged 6 to 12 years, without any ocular abnormalities other than refractive error were recruited for this study. They watched 3D TV for 50 minutes at a viewing distance of 2.8 meters. The image disparity of the 3D contents was from -1 to 1 degree. Refractive errors were measured both before and immediately after watching TV and were rechecked after a 10-minute rest period. The refractive errors before and after watching TV were compared. The amount of refractive change was also compared between myopes and controls. The refractive error of the participants who showed a myopic shift immediately after watching TV were compared across each time point to assure that the myopic shift persisted after a 10-minute rest. RESULTS: The mean age of the participants was 9.23 ± 1.75 years. The baseline manifest refractive error was -1.70 ± 1.79 (-5.50 to +1.25) diopters. The refractive errors immediately after watching and after a 10-minute rest were -1.75 ± 1.85 and -1.69 ± 1.80 diopters, respectively, which were not different from the baseline values. Myopic participants (34 participants), whose spherical equivalent was worse than -0.75 diopters, also did not show any significant refractive change after watching 3D TV. A myopic shift was observed in 31 participants with a mean score of 0.29 ± 0.23 diopters, which resolved after a 10-minute rest. CONCLUSIONS: Watching properly made 3D content on a 3D TV for 50 minutes with a 10-minute intermission at more than 2.8 meters of viewing distance did not affect the refractive error of children.

Changes in refractive error in patients with accommodative esotropia after being weaned from hyperopic correction.

BACKGROUND: To determine the long-term changes in refractive error and ocular alignment in patients with accommodative esotropia (AET) who were able to discontinue wearing hyperopic glasses because of emmetropisation. METHODS: Forty-seven patients with refractive AET who achieved emmetropisation and orthotropia without hyperopic glasses and were followed up for at least 3 years were enrolled. All of the patients had been prescribed the weakest possible glasses for best corrected vision. Refractive error and ocular alignment were analysed after the cessation of hyperopic glasses use. RESULTS: The mean length of follow-up was 5.7±3.21 years after successful weaning from hyperoptic glasses. The mean spherical equivalent (SE) of the refractive error was -1.01±1.53 dioptres (D), and the mean esotropia (ET) was 1.0±8.70 Δ at the final visit. Myopia developed in 55.3% of all patients. The mean myopic progression rate per year was -0.19±0.23 D/year. Forty-one patients (87.2%) showed orthotropia; in addition, three of the patients (6.4%) developed ET, and three (6.4%) developed exotropia (XT). The six patients who had ET or XT all showed myopia. Two of the three patients who developed ET underwent surgery. Both patients initially had a low degree of hyperopia and a high ratio of accommodative convergence to accommodation (AC/A). The initial hyperopia correlated with the SE refractive error at the final follow-up (p<0.001). CONCLUSIONS: When emmetropisation occurs early in patients with AET, it is necessary to note the development of myopia and the deterioration of ocular alignment.

Specific visual symptoms and signs of Meares-Irlen syndrome in Korean.

PURPOSE: To discriminate the visual symptoms and signs of Meares-Irlen syndrome (MIS) and nonspecific dyslexia from other ophthalmologic diseases (NODs). METHODS: Forty-five patients were enrolled. Thirty four of the patients with MIS whose symptoms improved with tinted lenses comprised MIS group. The other 11 patients whose reading difficulty improved with other ocular therapy and did not require tinted lenses comprised NODs group. The main symptoms causing dyslexia and associated ocular diseases were evaluated. RESULTS: The mean age was 17.9 ± 9.5 years in MIS group, and 19.3 ± 11.0 years in NODs group. In MIS group, the most common symptoms while reading were difficulty to move lines (85%), doubling (53%), and difficulty in bright condition (27%). On the other hand, blurring was the most common symptom in NODs group (45%). The associated ocular diseases in the two groups were refractive error (79% and 73%), dry eye (29% and 18%), and exophoria (6% and 27%), respectively. CONCLUSIONS: Doubling, difficulty to move lines, and difficulty in bright condition while reading are main specific symptoms in MIS compared to nonspecific dyslexia from other ophthalmologic disorders.

Stability of Y-splitting procedure combined with hang-back recession of the rectus muscle in rabbit eyes.

BACKGROUND: The Y-splitting procedure has been used both to treat up-shoots and down-shoots in Duane syndrome, and as a substitute for posterior fixation suture. The Y-split is often performed in conjunction with a hang-back recession when a large amount of recession or an adjustable suture is necessary. Herein, we evaluated the stability of Y-splitting hang-back recession in the rectus muscle. METHODS: Under general anesthesia, a 5-mm hang-back recession of the superior rectus muscle (SR) with Y-splitting was performed in ten eyes from ten rabbits (hang-back group). A conventional recession was performed in the SR of the fellow eye (control group). Six weeks after the procedure, the distance between the original insertion and the recessed SR (recession amount) and the width between the nasal and temporal halves of the SR were measured. These values were compared to the measurements taken at the time of surgery. RESULTS: The hang-back group had a significantly larger forward displacement than the control group (P < 0.001 for both the nasal and temporal halves). The width change between the nasal and temporal halves was also significantly larger in the hang-back group (4.94 ± 1.32 mm) than in the control group (1.14 ± 0.60 mm, P < 0.001). Additionally, the Y-configuration appeared to be more collapsed in the hang-back group than in the control group. CONCLUSION: Y-splitting of the rectus muscle may be unstable when it is combined with a hang-back recession. Surgeons should consider this possibility when performing Y-splitting procedures.

Applicability of scanning laser ophthalmoscopy microperimetry on the fixation patterns of monofixation syndrome.

OBJECTIVE: To investigate the monocular fixation pattern and characteristics in patients with monofixation syndrome using scanning laser ophthalmoscopy (SLO) microperimetry (MP). METHODS: Twenty-four patients older than 5 years who had 8 prism diopters (PD) or less of deviation after surgery were analyzed. The A group included 14 patients with infantile esotropia (ET), and 10 patients with acquired ET were assigned to B group. The monocular fixation pattern and characteristics of all patients were investigated using SLO MP. Central or mild eccentric fixation was defined as eyes with more than 50% of the fixation points located within the 2° diameter circle centred on the fovea. RESULTS: Mean ages at the time of surgery were 27 (range, 11-48) months in A group and 75 (range, 27-166) months in B group. Mean ages at the time of MP examination were 117 (range, 64-210) months in A group and 106 (range, 64-167) months in B group. Mean distant and near angles of esodeviation were -1.7 PD (-8 to 8) and -2.7 PD (-8 to 6) in A group and 0.6 PD (-2 to 8) and -0.4 PD (-2 to 0) in B group. Central or mild eccentric fixation was present in 8 patients (57%) and moderate or severe eccentric fixation in 6 patients (43%) in A group. In contrast, all patients in B group had central or mild eccentric fixation (p = 0.022). CONCLUSIONS: Postoperative moderate eccentric or severe eccentric fixations were observed in 43% of patients with infantile ET in either eye; however, all patients with acquired ET showed central or mild eccentric fixation in both eyes.

Risk factors predicting the need for additional surgery in consecutive esotropia.

PURPOSE: To evaluate the risk factors predicting surgical treatment in consecutive esotropia occurring after surgery for intermittent exotropia. METHODS: The clinical records of 52 patients with consecutive esotropia who underwent exotropia surgery were retrospectively reviewed. All patients demonstrated consecutive esotropia with diplopia or suppression for more than 1 month after surgery for exotropia. Patients were divided into two groups (the surgical group and nonsurgical group) depending on whether surgery was required for consecutive esotropia. Surgery for esotropia was performed only in patients with more than 10 prism diopters (PD) esodeviation that persisted for a minimum of 6 months, those who had suppression in 1 eye or diplopia, and those who could not achieve fine stereopsis. The nonsurgical treatment up to 6 months postoperatively was part-time patching and prism therapy in both groups. Patient characteristics were evaluated in the two groups. RESULTS: The surgical group was composed of 17 patients and the nonsurgical group was composed of 35 patients. Age, gender, refractive error, best-corrected visual acuity, and postoperative overcorrection at 1 day were not significantly different in the two groups (P > .05). However, the distance strabismic angle at 1 month postoperatively was 2.5 ± 3.8 PD esodeviation (range: 14 PD esotropia to 4 PD exotropia) in the nonsurgical group and 5.4 ± 5.1 PD esodeviation (range: 20 PD esotropia to orthotropia) in the surgical group; these values were statistically significant (P < .05). CONCLUSIONS: The clinically significant risk factor affecting the surgical decision for consecutive esotropia was a large esotropic angle at 1 month postoperatively in this study.

The advancement of the medial rectus muscle for consecutive exotropia.

OBJECTIVE: To characterize the dose effect of the advancement of the medial rectus muscle (MR) for consecutive exotropia (XT) after corrective surgery for infantile esotropia (ET) and provide a guide for achieving orthotropia. DESIGN: Retrospective cohort study. PARTICIPANTS: Seventy-seven patients with consecutive XT that developed after surgery for infantile ET. METHODS: All patients underwent advancement of the unilateral or bilateral MR and were followed up for at least 1 year. The angle of deviation and stereopsis were retrospectively reviewed from patient records. RESULTS: At the time of surgery for infantile ET, the mean eso-angle was 52.2 ± 13.10 prism diopters (PD; mean age, 28.5 ± 16.97 months). The exo-angle of consecutive XT was 25.6 ± 8.47 PD (mean age at surgery, 132.7 ± 82.32 months). The mean deviation was 1.8 ± 10.40 PD XT at the final follow-up (47.0 ± 43.57 months). The corrective effect of the exo-angle for a 1-mm advancement of the MR was 3.1 PD at 1 year after surgery and 2.9 PD at the last follow-up. There was a significant positive relationship between the preoperative exo-angle and the corrective effect of the 1-mm advancement of the MR at the last follow-up (r = 0.367, p < 0.05). Postoperatively, orthotropia was present in 79.2% of patients, re-exodrift in 16.9%, and ET in 3.9%. Favourable stereopsis was achieved in 73.2%. CONCLUSIONS: MR advancement was effective for treating consecutive XT, followed by recession of the MR for infantile ET, achieving favourable stereopsis. The corrective value was 3 PD per 1-mm advancement of the MR.

Postoperative minimal overcorrection in the surgical management of intermittent exotropia.

PURPOSE: To investigate the effect of initial postoperative minimal overcorrection on the result of the surgical management of intermittent exotropia based on long-term follow-up results. METHODS: 111 patients who underwent surgery for intermittent exotropia and were followed up for at least 5 years after surgery were retrospectively reviewed. The outcome was judged to be successful when there was 10 prism dioptres (PD) or less of exodeviation and less than 5 PD of esodeviation without any reoperation at the final follow-up visit. We evaluated the success, recurrence, overcorrection rate and the duration of diplopia according to their initial deviation. RESULTS: We divided patients into four groups based on their initial deviation: orthophoria or undercorrection (Ortho group, 31 patients), minimally overcorrected at 5 PD or less (MO group, 20 patients), usually overcorrected between 6 PD and 10 PD (UO group, 35 patients), and highly overcorrected at more than 10 PD (HO group, 25 patients). The success rate was 43-60% between the four groups (p=0.52). The recurrence rate was 28-57% (p=0.105), but post hoc analysis showed borderline p values between the Ortho and HO group (p=0.024). No overcorrection was noted in the Ortho and MO groups (p=0.04). The duration of diplopia was 0-2.5 weeks, showing statistically significant difference among groups (p<0.001). CONCLUSIONS: The amount of initial postoperative overcorrection may not predict the long-term success rate. However, the MO group showed a lower recurrence rate than the Ortho group and also showed no overcorrection and a shorter duration of postoperative diplopia than the UO and HO groups.

Change in the location of the equator and recessed muscles in young rabbit eyes.

PURPOSE: To study the changes in the location of the equator and the new insertion of extraocular muscle after recession surgery in a rabbit model. METHOD: An experimental study was performed in ten eyes of five rabbits. Eyes were divided into two groups according to the amount of recession. In right eyes, 5 mm superior recti (SR) muscle recession, approximately 2 mm posterior to the equator, was performed (5 mm recession group), while in the left eyes, 3 mm recession was performed to the location of the equator (3 mm recession group). We measured the distance of the equator from the limbus, as well as the distance between the superior rectus insertion and the equator. The preoperative measurements were compared with the results 2 months after the surgery. The change in location of the superior rectus and the equator was compared between the two eyes. RESULT: The recessed SR muscle did not show any significant change in location in both groups (p = 0.18 and 0.16 respectively). However, the location of the equator of rabbit eye showed movement of about 1 mm posterior to the initial location with the growth of the eyeballs (p = 0.04 and 0.03, respectively). CONCLUSION: The location of the equator moved posteriorly at 2 months postoperatively in young rabbit model while the insertion of the recessed SR did not show any significant movement.

3D asthenopia in horizontal deviation.

PURPOSE: This study was conducted to investigate the asthenopic symptoms in patients with exotropia and esotropia while watching stereoscopic 3D (S3D) television (TV). METHODS: A total 77 subjects who more than 9 years of age were enrolled in this study. We divided them into three groups; Thirty-four patients with exodeviation (Exo group), 11 patients with esodeviation (Eso group) and 32 volunteers with normal binocular vision (control group). The S3D images were shown to all patients with S3D high-definition TV for a period of 20 min. Best corrected visual acuity, refractive errors, angle of strabismus, stereopsis test and history of strabismus surgery, were evaluated. After watching S3D TV for 20 min, a survey of subjective symptoms was conducted with a questionnaire to evaluate the degree of S3D perception and asthenopic symptoms such as headache, dizziness and ocular fatigue while watching 3D TV. RESULTS: The mean amounts of deviation in the Exo group and Eso group were 11.2 PD and 7.73PD, respectively. Mean stereoacuity was 102.7 arc sec in the the Exo group and 1389.1 arc sec in the Eso group. In the control group, it was 41.9 arc sec. Twenty-nine patients in the Exo group showed excellent stereopsis (≤60 arc sec at near), but all 11 subjects of the Eso group showed 140 arc sec or worse and showed more decreased 3D perception than the Exo and the control group (p < 0.001, Kruskal-Wallis test). The Exo group reported more eye fatigue (p < 0.001, Kruskal-Wallis test) than the Eso and the control group. However, the scores of ocular fatigue in the patients who had undergone corrective surgery were less than in the patients who had not in the Exo group (p < 0.001, Kruskal-Wallis test) and the amount of exodeviation was not correlated with the asthenopic symptoms (dizziness, r = 0.034, p = 0.33; headache, r = 0.320, p = 0.119; eye fatigue, r = 0.135, p = 0.519, Spearman rank correlation test, respectively). CONCLUSION: Symptoms of 3D asthenopia were related to the presence of exodeviation but not to esodeviation. This may indicate that S3D symptoms are closely related to the convergence demand.

Postoperative changes in spatial localization following exotropia surgery.

PURPOSE: To measure changes in spatial localization following exotropia surgery using a computer touch-screen method of measurement. METHODS: Enrolled in the study were 60 exotropia patients, all of whom had undergone corrective muscle surgeries under general anesthesia: 37 patients had undergone unilateral lateral rectus or bilateral lateral rectus muscle recession procedures (recession group) and 23 patients had undergone unilateral lateral and medial rectus muscle resection (R&R), or unilateral medial rectus resection only (resection group). We evaluated spatial localization by having patients point to targets on a computer touch-screen before surgery, and 1 day and 1 month after surgery. The pointing error, Δp, is defined as the difference between the actual location of the target and the pointed-to location of the target by unsigned value, was recorded as the mean of five tests. We compared the extent of postoperative changes in Δp between the two groups. RESULTS: The mean Δp before surgery did not differ statistically between the two groups (p = 0.93). One day after surgery, however, the postoperative change in Δp of the resection group compared with that of the recession group (2.0 ± 0.7° and 0.4 ± 0.5°, respectively) was significant (p = 0.01 and p = 0.86 respectively). CONCLUSIONS: The ability for spatial localization is decreased in patients immediately following medial rectus resection, but is regained by 1 month following surgery.

Self-grading effect of inferior oblique recession.

PURPOSE: Inferior oblique (IO) myectomy can result in self-adjustment; the greater the preoperative hyperdeviation, the larger the postoperative correction. This study estimated the effect of IO recession in primary position and in contralateral gaze. METHODS: Records of 43 patients with IO muscle overaction associated with congenital unilateral superior oblique palsy were reviewed retrospectively. Seventeen patients who had a unilateral 10-mm recession (IO attached at 2 mm temporal and 3 mm posterior from the inferior rectus muscle insertion) and 26 patients who had a standard 14-mm recession were evaluated at 3 months postoperatively. The effect of the recession was measured by preoperative hyperdeviation minus postoperative hyperdeviation. RESULTS: The average preoperative hyperdeviation was 13.4 ± 4.83 prism diopters (PD) in primary position and 16.2 ± 6.32 PD in contralateral gaze in the 10-mm group and 8.0 ± 3.48 PD in primary position and 12.76 ± 4.55 PD in contralateral gaze in the 14-mm group. The average deviation at 3 months postoperatively was 2.1 ± 3.03 in primary position and 2.6 ± 3.95 PD in contralateral gaze in the 10-mm group and 0.8 ± 1.21 in primary position and 1.8 ± 1.95 PD in contralateral gaze in the 14-mm group. The range of self-adjusting effect at 3 months postoperatively was 3 to 20 PD in primary position and 5 to 30 PD in contralateral gaze in the 10-mm group and 3 to 15 PD in primary position and 4 to 24 PD in contralateral gaze in the 14-mm group. The self-grading effect was large and displayed no significant differences at 3 months postoperatively in the 10- and 14-mm groups (P = .104 and .560, respectively). CONCLUSION: Both IO recession procedures were largely self-grading and no significant differences were evident at 3 months postoperatively.

Postoperative stabilization of the strabismic angle in intermittent exotropia.

PURPOSE: To analyze the postoperative strabismic angle for five years or more and to investigate when the angle stabilized in intermittent exotropia. METHODS: We retrospectively reviewed the clinical records of 89 patients who had undergone surgery for intermittent exotropia. The postoperative strabismic angles measured were analyzed at one-year intervals up to five years postoperatively. We divided them into two groups according to their age at the time of surgery. Group 1 was less than 5 years of age, while Group 2 participants were 5 years of age or older. RESULTS: For our 89 total patients, average exo-angles were 7.8 ± 7.26, 7.9 ± 7.51, 9.5 ± 7.05, 10.1 ± 6.87, and 9.4 ± 6.90 prism diopters at one, two, three, four, and five years postoperatively, respectively. Average exo-angles between postoperative year one and year three, as well as between postoperative year two and year three, were statistically significant (p = 0.015, 0.022). However, the angles were not statistically significant between postoperative year three and year four or between years three and five, respectively (p = 0.707, p = 0.948). The stabilization characteristics of the angle were somewhat different according to age group. In Group 1, the average exo-angle in postoperative years one and three were statistically significant (p = 0.016), but the angle in the same period was not statistically significant in Group 2 (p = 0.203). CONCLUSIONS: There was no significant interval change after three years postoperatively in intermittent exotropia, but if the patient's age at surgery was 5 years or higher, no significant change of exo-angle was found following postoperative year one in this study.

Three-dimensional display-induced transient myopia and the difference in myopic shift between crossed and uncrossed disparities.

PURPOSE: To investigate whether three-dimensional (3D) images cause nearwork-induced transient myopia (NITM) more than 2D images and whether there is any difference between 3D images with crossed and uncrossed disparities in the development of NITM. METHODS: Twenty-five volunteers, enrolled in this study, watched 2D and 3D movies and read 3D texts with crossed and uncrossed disparities for 2 to 3 hours with spectacle correction. The viewing distance was 50 to 70 cm. The refractive error was measured before and after each visual task. If there was a myopic shift after a task, the refractive error was measured at 3-minute intervals until it was resolved. The changes in the refractive error and the amount of NITM were evaluated and compared. RESULTS: The mean age of volunteers was 27.8 ± 2.87 years, and the mean refractive error before the visual tasks was -4.19 ± 2.87 diopters (D). Thirteen subjects (52%) showed NITM after watching a 2D movie, whereas 20 subjects (80%) had NITM after a 3D movie (P = 0.037). The mean extent of NITM was 0.36 ± 0.27 D after watching a 3D movie and 0.10 ± 0.28 D after a 2D movie (P = 0.002). The 3D text with crossed disparity significantly induced NITM (P < 0.001), but that with uncrossed disparity did not. There was a tendency for the NITM to persist longer after subjects watched a 3D movie than after a 2D movie. CONCLUSIONS: Viewing 3D images with crossed disparity induced a greater degree of NITM than 2D images. These results suggest that the greater NITM induced by 3D images may have a greater effect on the development and progression of permanent myopia.

Contemplation of the surgical normogram of lateral rectus recession for exotropia associated with superior oblique palsy.

PURPOSE: To suggest a surgical normogram for lateral rectus recession in exotropia associated with unilateral or bilateral superior oblique muscle palsy (SOP). METHODS: We retrospectively reviewed the charts of 71 patients with exotropia who were successfully corrected over one year. Each patient had undergone unilateral or bilateral rectus recession associated with uni- or bilateral inferior oblique (IO) 14 mm recession, using a modified surgical normogram for lateral rectus (LR) recession, which resulted in 1 to 2 mm of reduction of LR recession. We divided all patients into 2 groups, the 34 patients who had undergone LR recession with unilateral IO (UIO) recession group and the remaining 37 patients who had undergone LR recession with bilateral IO (BIO) recession group. Lateral incomitancy was defined when the exoangle was reduced by more than 20% compared to the primary gaze angle. The surgical effects (prism diopters [PD]/mm) of LR recession were compared between the two groups using the previous surgical normogram as a reference (Parks' normogram). RESULTS: The mean preoperative exodeviation was 20.4 PD in the UIO group and 26.4 PD in the BIO group. The recession amount of the lateral rectus muscle ranged from 4 to 8.5 mm in the UIO group and 5 to 9 mm in the BIO group. Lateral incomitancy was noted as 36.4% and 70.3% in both groups, respectively (p = 0.02). The effect of LR recession was 3.23 ± 0.84 PD/mm in the UIO group and 2.98 ± 0.62 PD/mm in the BIO group and there was no statistically significant difference between two the groups (p = 0.15). CONCLUSIONS: Reduction of the LR recession by about 1 to 2 mm was successful and safe to prevent overcorrection when using on IO weakening procedure, irrespective of the laterality of SOP.

Inferior oblique transposition onto the equator: the role of the equator in development of contralateral inferior oblique overaction.

PURPOSE: To investigate the role of the location of the equator and orientation of newly attached inferior oblique (IO) muscle in the development of contralateral inferior oblique overaction (IOOA). METHODS: Fourteen patients (14 eyes) with 5 to 12 prism diopters (PD) of hyperdeviation in primary position with unilateral, congenital, superior oblique palsy were included. Seven patients underwent modified IO transposition onto the equator (equator group) and seven patients underwent modified IO 14-mm recession (14-mm group). IOOA in the contralateral eye and the angle of strabismus were assessed at 3 months postoperatively. RESULTS: Mean angles of hyperdeviation in primary gaze and sursoadduction were 0.7 and 2.1 PD in the equator group and 0.6 and 2.4 PD in the 14-mm group, respectively. Six patients (86%) developed anti-elevation syndrome and four patients (57%) showed definite 2+ or higher IOOA in the contralateral eye in the equator group. Three patients (43%) in the 14-mm group also developed contralateral IOOA, although it was 1+ or less. The postoperative difference in contra-lateral IOOA between groups was statistically significant (P = .04). CONCLUSION: This finding suggests that vertical orientation of the IO muscle is another important contributor in the development of contralateral IOOA in addition to the location of the newly attached IO muscle.

Can the preoperative fundus extorsion in infantile esotropia predict the development of postoperative inferior oblique overaction and dissociated vertical deviation?

OBJECTIVE: To evaluate the relationship between fundus extorsion before surgery and the development of inferior oblique overaction (IOOA) and dissociated vertical deviation (DVD) after surgery in patients with infantile esotropia. DESIGN: Retrospective comparative observational study. PARTICIPANTS: Forty patients who had not had preoperative IOOA or DVD, and had undergone surgery for infantile esotropia were included. METHODS: A fundus examination was carried out under general anesthesia before surgery. There were 21 subjects with preoperative fundus extorsion (extorsion group), and 19 subjects without torsion (no torsion group). The development of IOOA and DVD after surgery was evaluated. RESULTS: After surgery, IOOA developed in 14 patients (66.7%) and DVD in 17 patients (80%) in the extorsion group. In contrast, IOOA developed in 2 patients (10.5%) and DVD in 6 patients (31.6%) in the no torsion group (p < 0.001, p = 0.002, respectively). CONCLUSIONS: When patients with infantile esotropia had fundus extorsion assessed on general anesthesia before surgery, IOOA and DVD were more likely to develop after surgery.

Analysis of the effects of medial rectus muscle resection for recurrent exotropia.

PURPOSE: The purpose of this paper is to investigate how much correction is obtained per millimeter of medial rectus (MR) resection for recurrent exotropia after bilateral lateral rectus (BLR) recession, and to determine the difference in the effects between unilateral and bilateral resection, and the influence of previous lateral rectus (LR) recession on the effects of MR resection. METHODS: A total of 59 patients who had undergone MR resection after BLR recession were included in this study. The unilateral group consisted of 38 patients and bilateral group, 21 patients. Thirty patients in the unilateral group were divided into two groups: patients who had undergone previous LR recession of 7 mm or greater (21 patients) and less than 7 mm (9 patients). Main outcome measures were average deviation corrected per millimeter of MR resection at 1 month postoperative. RESULTS: The average effect of MR resection was 4.2 prism diopters (PD, 2.0 to 6.7 PD)/mm. The average effect in the unilateral group was 4.2 PD/mm and 4.1 PD/mm in the bilateral group. There was no significant difference between groups (P = 0.60). The average effect in the recession 7 mm or greater group was 4.0 PD/mm, and the average effect in the recession less than 7 mm group was 4.2 PD/mm (P = 0.698). CONCLUSIONS: The effect of MR resection per millimeter was variable. The laterality and previous amount of LR recession did not influence the effect of MR resection. These variable outcomes dictate that caution be exercised when MR resection is performed for recurrent exotropia.