Inferior Oblique Overaction Research Articles

Effect of bilateral inferior oblique partial myectomy on V pattern exotropia with inferior oblique overaction

PurposeTo compare the effect of bilateral inferior oblique partial myectomy on V-pattern exotropia patients with bilateral symmetric inferior oblique overaction (IOOA) and asymmetric IOOA.MethodsThis was a retrospective study including 53 V-pattern exotropia patients with bilateral IOOA of all grades who underwent bilateral inferior oblique partial myectomy. Success was defined as the elimination of the IOOA and the collapse of the V pattern at the final follow-up. The fovea-disc angle (FDA) and V-pattern exotropia were compared before and after surgery.ResultsThis study included 53 V-pattern exotropia patients, containing 29 patients with symmetric IOOA (Group I) and 24 patients with asymmetric IOOA (Group II). The last follow-up ranged from 3 to 16 months (mean of 5 months). After myectomy, 3 eyes in Group I and 2 eyes in Group II were observed with residual grade 1 IOOA. The surgical success rates of IOOA correction in Group I and Group II were 96% and 95%, respectively. The difference was not statistically significant (P = 0.808). V-pattern exotropia collapsed with residual 2 (min. 0, max. 6) PD for Group I and 2 (min. 0, max. 10) PD for Group II, and there was a statistically significant difference between pre- and postoperative V-pattern exotropia in the two groups (P = 0.000). No inferior oblique (IO) underaction or antielevation syndrome (AES) was found in either group. The average preoperative FDA of the right eye and the left eye was (8.93 ± 4.34)° and (10.86 ± 4.27)° in Group I and (9.08 ± 4.92)° and (11.00 ± 5.69)° in Group II. There was a significant difference in preoperative FDA between the right eye and the left eye in the two groups (Group I p = 0.029; Group II p = 0.038).ConclusionsBilateral inferior oblique partial myectomy can bring “symmetric” effectiveness in the correction of IOOA and FDA. It can potentially be used as a safe and successful treatment for V-pattern exotropia with bilateral IOOA. In addition, the FDA may be a promising index for evaluating fundus extorsion.

Asymmetric Bilateral Inferior Oblique Transposition of a Bilateral Inferior Oblique Overaction Associated with Dissociated Vertical Deviation

Purpose: Inferior oblique overaction with a dissociated vertical deviation occurs secondary to infantile exotropia or esotropia. In terms of correction, asymmetric bilateral inferior oblique transposition has been the treatment of choice, but the surgical amount depended largely on the surgeon’s experience. We report successful bilateral inferior oblique transposition using our own standard methods.Methods: We performed a retrospective medical chart review of patients with bilateral inferior oblique overaction and dissociated vertical deviation who underwent bilateral inferior oblique transposition at the Korea University Medical Center from January 2013 to December 2020. We performed either symmetric or asymmetric transposition; the reattachment sites of the bilateral inferior obliques were determined according to preoperative differences of the inter-eye deviations of dissociated vertical deviation. When the differences were < 5 prism diopters, correction was considered successful. To avoid the development of anti- elevation syndrome, the inferior oblique muscles were re-attached near the equator.Results: Twenty-three patients were analyzed, all of whom underwent bilateral inferior oblique transposition; 12 required additional horizontal muscle surgery. The deviation difference (both eyes) and inferior oblique overaction grade were significantly lower postoperatively. We did not encounter any case of anti-elevation syndrome.Conclusions: The surgical extent of asymmetric bilateral inferior oblique transposition should reflect the difference in dissociated vertical deviation the two eyes.

Transposición del vientre del oblicuo inferior sin desinserción en el tratamiento de la hipertropia en aducción

PurposeTo evaluate the efficacy and safety of inferior oblique muscle transposition and myopexy in patients with mild/moderate inferior oblique muscle overaction, with or without diplopia. MethodWe retrospectively analysed data for the 12 patients who underwent the technique. Data were collected from October 2018 to September 2021. Surgery was performed by suturing the inferior oblique belly to the sclera at 5mm posterior to the temporal end of the inferior rectus. All 12 patients had mild hypertropia (≤6 prism diopters [pd]) in primary position and mild/moderate inferior oblique overaction. Mean preoperative hypertropia was 4.42pd ±1.62. Diplopia was recorded in 10 cases. The diagnoses were fourth nerve paresis (9), unilateral primary inferior oblique overaction (2) and dissociated vertical deviation (1). Torticollis was observed in 7 cases, 2 had subjective torsion and 2 objective torsion. ResultsMean age was 46.86±25.1 years (50%: men). Diplopia resolved in 9 of the 10 cases. The mean final vertical deviation was 1.5±2.93 (P=.001) pd in straight gaze. Of 7 mild overshoot in adduction, it disappeared in 3 and 4 remained the same. Of 5 moderate overshoot in adduction, 2 improved to mild and 3 disappeared. Torticollis was eliminated in 5 patients and improved in another 2. Mean time from surgery was 14.08±8.05 months. There were no overcorrections. ConclusionsInferior oblique muscle transposition with myopexy is a safe and effective procedure in patients with mild-to-moderate inferior oblique muscle overaction and small-angle hypertropia, with or without diplopia.

Differences in gene expression between the primary and secondary inferior oblique overaction.

BackgroundThis study sought to define different adaptive changes in the molecular levels of the overacting inferior oblique muscle in primary and secondary inferior oblique overaction.MethodsThe inferior oblique muscles of patients with congenital superior oblique palsy (SOP) and those of patients with congenital esotropia were collected during surgery. RNA-seq technology was performed to detect the differentially expressed genes (DEGs) between the two groups. A comprehensive analysis of the gene expression profiles was then conducted, including the identification of DEGs, a Gene Ontology (GO) analysis, and a gene set enrichment analysis (GSEA). Finally, a protein-protein interaction (PPI) network was constructed with Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) and Cytoscape software.ResultsWe identified 221 DEGs, of which 104 were significantly upregulated and 117 were downregulated in the SOP group. Additionally, several isoforms of the myosin heavy chain (MyHC) gene were found to be significantly and differentially expressed in the SOP group, including 3 upregulated fast-twitch MyHC isoforms (i.e., MYH1, MYH4, and MYH13) and 1 downregulated slow-twitch MyHC isoform (i.e., MYH3). The GO analysis indicated that the upregulated DEGs were mainly enriched in the muscle system process and muscle contraction. The GSEA analysis revealed that the upregulated pathways of ribosome, proteasome, oxidative phosphorylation, fatty acid metabolism, viral myocarditis, and cardiac muscle contraction were enriched.ConclusionsOur findings provide insights into the different molecular changes of inferior oblique muscle overaction secondary to SOP and suggest the potential pathological mechanisms of inferior oblique overaction (IOOA) in SOP. The results suggest that upregulated fast-twitch MyHC isoforms and downregulated slow-twitch MyHC isoform in SOP may contribute to the increased force of its inferior oblique muscle.

Factors Affecting Stereopsis in Patients with Refractive Accommodative Esotropia

Objective: Aim of this study was to evaluate possible risk factors affecting stereopsis in patients with refractive accommodative esotropia (RAE). Materials and Methods: The retrospective investigation was performed on the records of children with RAE. Two groups were made according to the presence of stereopsis. The presumed onset age of RAE, age at the initial refractive correction, mean best-corrected visual acuity (BCVA), mean angle of deviations in near and distance, presence of strong fixation preference, spherical equivalent (SE), and cylindrical error values, mean interocular differences in BCVA were compared between groups. Besides, mean SE and ocular movement disorders were also evaluated and compared between groups, statistically. Results: The mean age of 66 children was 10,7±2,9 years. The mean follow-up time was 65,3±25,6 months. 38 children had measurable stereoacuity and 28 children who had not and composed groups 1 and 2, respectively. There were statistically significant differences between groups in terms of mean BCVA, the interocular difference in BCVA, mean SE, presence of amblyopia, and the presence of inferior oblique overaction. Conclusion: Presence and depth of amblyopia, lower best-corrected visual acuity, higher spherical equivalent, and concomitant inferior oblique overaction were found to be potential risk factors for the maldevelopment of stereopsis in patients with refractive accommodative esotropia.

Graded recession technique versus myectomy in management of inferior oblique muscle overaction

Aim The aim of this study was to compare two surgical techniques of inferior oblique muscle weakening in the management of inferior oblique overaction whether primary or secondary, that is, inferior oblique myectomy and graded inferior oblique muscle recession. Patients and methods This is a randomized prospective study, performed in Alexandria, Egypt, that included cases of inferior oblique muscle overaction, whether primary or secondary, starting on May 2020. It included 40 patients, divided into two groups: group I included 20 patients who were managed by inferior oblique myectomy, and group II included 20 patients who were managed by graded inferior oblique muscle recession, according to the clinical grading of overaction. Results The results of the two groups were compared, and it was found that the results were comparable as the final outcomes of correction of hypertropia were satisfactory in both groups. Conclusion As the results in both techniques have no significant difference, it is recommended that each surgeon should perform his/her preferred technique.

Clinical features of excyclotorsion in the non-paretic eye of patients with congenital unilateral superior oblique palsy

BackgroundTo investigate preoperative clinical features and postoperative results according to the correspondence between excyclotorsion and the paretic eye in patients with congenital unilateral superior oblique palsy (USOP).MethodsA retrospective review of medical charts was performed. The patients were divided into the accordance (ocular excyclotorsion in the paretic eye) and disaccordance (ocular excyclotorsion in the non-paretic eye) groups. The degree of excyclotorsion (scale, 0–4) was measured. Age, sex, hypertropia at the primary position, fixation preference, inferior oblique overaction, and degree of excyclotorsion were measured.ResultsNinety-eight patients were included in this study. There were 70 (71.4%) and 28 patients (28.6%) in the accordance and disaccordance groups. Sixteen patients (22.9%) in the accordance group and 12 patients (42.9%) in the disaccordance group were aged under 2 years (p = 0.04). A fixation preference of the paretic eye was observed in 2 (2.9%) and 8 (28.6%) patients in the accordance and disaccordance groups (p < 0.01). The postoperative degree of excyclotorsion in the accordance group (0.14 ± 0.39) was lower than that in the disaccordance group (0.28 ± 0.71) (p = 0.01). The residual postoperative excyclotorsion (> 1) were observed in the disaccordance group (14 patients, 50%) and accordance group (16 patients, 22.9%) (p = 0.01).ConclusionPreoperative disaccordance between excyclotorsion and the paretic eye was observed in patients who were under 2 years of age and preferred fixation of the paretic eye. The postoperative degree of excyclotorsion was lower in the accordance group.

Inferior oblique anterior transposition according to a different grading scale for hyperdeviation with inferior oblique overaction

ObjectifDéfinir une échelle de classement de la transposition antérieure de l'oblique inférieur (IOAT, pour inferior oblique anterior transposition) chez des patients présentant une hyperdéviation et une hyperaction de l'oblique inférieur (IOOA, pour inferior oblique overaction), selon des données issues de notre étude rétrospective antérieure. NatureÉtude de cohorte prospective. ParticipantsTrente-huit patients qui ont fait l'objet d'un classement de l'IOAT. MéthodesLes patients ont été répartis en 5 groupes en fonction de l'importance de l'hyperdéviation en position primaire (PPHD, pour primary position hyperdeviation). L'oblique inférieur a été transposé soit à 2 mm postérieur, à 1 mm postérieur, en parallèle, à 1 mm antérieur ou à 2 mm antérieur à l'insertion du droit inférieur, respectivement. La réussite de l'intervention chirurgicale se définissait comme suit : réussite complète (PPHD ≤ 3 dioptries prismatiques [DP]), réussite partielle (PPHD > 3 et ≤ 6 DP) et échec (PPHD > 6 DP). RésultatsLa correction moyenne de l'hyperdéviation par groupe après l'IOAT se chiffrait à 9,50 ± 0,9 DP (fourchette : 8–10 DP), à 12,43 ± 1,5 DP (fourchette : 11–14 DP), à 16,67 ± 1,4 DP (fourchette : 15–18 DP), à 19,57 ± 1,7 DP (fourchette : 16–21 DP) et à 22,57 ± 5,8 DP (fourchette : 14–30 DP), respectivement. L'intervention a été une réussite chez 34 patients (89,5 %), une réussite partielle chez 3 patients (7,9 %) et un échec chez 1 patient (2,6 %). Tous les patients de notre étude présentaient une IOOA unilatérale avant l'intervention; une IOOA est apparue dans l’œil controlatéral de 9 patients (23,7 %) pendant le suivi postopératoire. Une limitation de –2 du regard vers le haut est apparue chez 4 patients (57,1 %) du groupe 5, sans qu'il soit besoin de recourir à la chirurgie. ConclusionsIl est possible d'obtenir un taux élevé de réussite grâce à notre échelle de classement de l'IOAT en présence d'IOOA primaire et secondaire s'accompagnant d'une hyperdéviation en position primaire.

Different Surgical Approaches for treatment of isolated dissociated vertical deviation without inferior oblique overaction.

To report the surgical results on superior rectus recession (SRR) and inferior oblique anterior transposition (IOAT) for cases with isolated bilateral dissociated vertical deviation（DVD）without inferior oblique overaction (IOOA). A retrospective review was conducted for cases with isolated bilateral DVD without IOOA who were surgically treated using either bilateral SRR (SRR group) or IOAT (IOAT group). Pre- and post-operative ocular motility, ocular alignment, amount of DVD and complications were compared between the two groups. Records from 37 cases were reviewed. Preoperative levels of DVD (M ± SD) in the SRR group (N = 18) of 19.88 ± 6.72 prism diopter (PD) in the right eye and 19.54 ± 5.64 PD in the left eye, were reduced to 4.94 ± 7.26 PD and 4.11 ± 3.91 PD respectively after surgery (P＜0.0001 for both). Preoperative levels of DVD (M ± SD) in IOAT group (N = 19) of 15.89 ± 6.35 PD in the right eye and 18.58 ± 9.27 PD in the left eye, were reduced to 3.42 ± 4.49 PD and 3.42 ± 4.88 PD respectively after surgery (P＜0.0001 for both). Inferior oblique (IO) muscle function remained normal after surgery. Overall, outcomes within the SRR group revealed that 10 patients showed a complete resolution of their condition, 6 effective responses and 2 failures. In the IOAT group, 13 patients showed a complete resolution of their condition, 5 effective responses and 1 failure. There were no statistically significant differences between the two groups (Z = 0.48). SRR and IOAT were both effective in treating isolated DVD without IOOA with similar satisfactory results obtained for both procedures.

Conventional surgery versus botulinum toxin injections for partially accommodative esotropia

To compare the effect of botulinum toxin injection (BTX) to bilateral medial rectus recession (BMR) in partially accommodative esotropia (PAET). The medical records of children 1-14 years of age treated for PAET with BMR or BTX between 2010 and 2020 at a single institution were reviewed retrospectively. PAET was defined as residual esotropia of at least 14Δ after 6 weeks of continuous wear of full cycloplegic refraction (> +2.5 D). Success was defined as esotropia of 0Δ-10Δ after a single surgery or ≥1 BTX injections. Of 224 patients, 121 received BTX and 103 underwent BMR. BMR showed a higher success rate than BTX (70.9% vs 53.7% [P = 0.006]). BMR was more successful in males, in patients >5 years of age, and when spherical equivalent was ≤ +5.00 D (79.2%, 74.3%, and 67.5%, resp. [P < 0.05]). Mean follow-up was shorter in the BMR group than in the BTX group (16.7 ± 14.7 vs 31.4 ± 29.5 months [P = 0.0001]). Mean duration of surgery was significantly shorter in the BTX group (5.2 ± 4.3 vs 70.5 ± 31.4 min [P = 0.0001]). Postoperative inferior oblique overaction was more common in the BTX group (7.4%; P = 0.02 [Fisher exact test]), and persistent ptosis was only seen in the BTX group (0.8%); consecutive exotropia was only seen in the BMR group (2%). In our study cohort, BMR had a higher success rate than BTX. Conventional surgery allowed for shorter follow-up and fewer complications than BTX in the treatment of PAET.

Spontaneous Consecutive Exotropia After Conservative Management of Accommodative Esotropia

Spontaneous consecutive exotropia (SCXT) in conservatively managed accommodative esotropia is not widely discussed. The author presents a case series of 4 patients with SCXT describing patient characteristics and possible risk factors. Management modifications based on this series are proposed. Four cases of patients who initially presented with accommodative esotropia and later developed SCXT are presented. The age range at presentation was between 4 months to 3 years, with total follow-up ranging between 8–15 years. All four cases presented with esotropia on or before the age of 3 years, with initial hyperopia ranging between +1.50 to +4.25. The SCXT occurred between ages 2–7 years. Possible risk factors identified include amblyopia, dissociated vertical deviation, rapid control of esodeviation, inferior oblique overaction, and poor follow-up during the course of their strabismus. The author recommends earlier tapering of hyperopia correction following initial control with full cycloplegic refraction. Identified risk factors should alert the specialists to be wary of SCXT.

Analysis of the effect of inferior oblique overaction on the retinal layers and choroidal thicknesses

Analysis of the effect of inferior oblique overaction on the retinal layers and choroidal thicknesses

Changes in Hypertropia in Patients with Asymmetric Inferior Oblique Overaction after Symmetric Inferior Oblique Myectomy

Purpose: This study assessed the effects of bilateral inferior oblique myectomy for hypertropia on the preoperative vertical deviation angle in patients with asymmetric primary inferior oblique overaction (IOOA).Methods: This study included patients who underwent bilateral inferior oblique myectomy and lateral rectus recession due to asymmetric primary IOOA and intermittent exotropia, and were followed up for at least 6 months postoperatively. Pre- and post-operative vertical deviation angles were compared. The correlation between the extent of correction of vertical deviation after surgery and residual hypertropia, according to the preoperative degree of vertical deviation and difference between bilateral IOOA, was evaluated.Results: This study included 178 eyes from 89 patients. The angle of hypertropia in the primary position was reduced from 3.2 ± 2.2 prism diopters (PD) preoperatively to 0.5 ± 2.5 PD postoperatively (Wilcoxon signed-rank test, p &lt; 0.001). No significant correlation was observed between the preoperative interocular difference in IOOA and postoperative extent of correction of the vertical deviation (r = 0.044, p = 0.684), or between the preoperative difference in bilateral IOOA and residual hypertropia (Spearman's rank-order correlation, r = -0.084, p = 0.432). Increased preoperative hypertropia correlated with a greater extent of surgical correction of the vertical deviation (r = 0.733, p &lt; 0.001). Preoperative hypertropia had no significant correlation with residual hypertropia (Spearman's rank-order correlation, r = 0.182, p = 0.087).Conclusions: In symmetric bilateral inferior oblique myectomy with bilateral lateral rectus recession for asymmetric bilateral primary IOOA with V-type intermittent exotropia, a positive correlation between the degree of preoperative vertical deviation and extent of correction of the vertical deviation was observed. Additionally, IOOA and hypertropia were significantly improved postoperatively.

The Role of Hypertropia in the Surgical Management of Bilateral Inferior Oblique Muscle Overaction

ABSTRACT Purpose Inferior oblique muscle overaction (IOOA) is an ocular motility anomaly consisting of overelevation in adduction, often associated with ipsilateral hypertropia. The weakening procedure of IO muscle is the most widely used procedure in IOOA. Usually, surgical planning is based on the degree of overaction of the IO muscle. Materials and Methods We have retrospectively analyzed patients with bilateral IOOA with and without hypertropia in primary position, who underwent a bilateral IO weakening procedure. Both the amount of IOOA and the presence of a hypertropia in primary position were taken into consideration for the surgical plan. Results Nineteen patients met the entry criteria for this study. In 12 patients, a hypertropia in primary position was present at baseline, and it was significantly lower after the asymmetrical IO weakening: 11 had an asymmetric IOOA at baseline, and one had symmetric IOOA. None of the remaining seven patients had a vertical deviation in primary position before surgery, despite having asymmetric IOOA. None of them developed a hypertropia in primary position after symmetric IO weakening. Conclusions Our findings outline the utility of considering both the presence of a vertical deviation in primary position and the magnitude of IOOA in this set of patients. Asymmetric inferior oblique weakening procedure is effective in treating a hypertropia in the primary position and bilateral IOOA.

The Effects of Modified Graded Recession, Anteriorization and Myectomy of Inferior Oblique Muscles on Superior Oblique Muscle Palsy.

Background: The aim was to investigate the effect of inferior oblique (IO) operation (IO myectomy or graded recession and anteriorization) for unilateral and bilateral superior oblique muscle palsy (SOP); Methods: A total of 167 eyes undergoing IO surgery by a single surgeon between 2008 and 2015 were retrospectively reviewed. The method for treating symmetric bilateral SOP was bilateral IO myectomy (n = 102) and the method for treating unilateral SOP or non-symmetric bilateral SOP was IO-graded recession and anteriorization (n = 65). Associated clinical results and other factors were analyzed; Results: Head tilt, vertical deviation, IO overaction, SO underaction degree and ocular torsion angle were all clearly changed, but there was no statistically significance between these two procedures. Mean preoperative torsional angle was 15.3 ± 6.4 degree, which decreased to 5.3 ± 2.7 degree after surgery. Preoperative torsional angle, IOOA and SOUA degree were all significantly affected in postoperative torsional angle (p = 0.025, 0.003 and 0.038). Horizontal rectus muscle and IO muscle operation did not interfere with each other’s results (p = 0.98); Conclusions: Symmetric bilateral SOP could be treated with bilateral IO myectomy and IO-graded recession and anteriorization should be reserved for unilateral SOP or non-symmetric bilateral SOP.

Surgical treatment of consecutive exotropia: Comparison of different surgical methods applied to one eye in one session.

To compare the different surgical methods performed on a single eye in a single session and the factors that affect the success of patients having consecutive exotropia (XT) developed after esotropia surgery. The medical data of the patients who underwent surgery for consecutive XT were reviewed retrospectively. Patients with followed of 6 months or more were divided into four groups; patients with medial rectus (MR) advancement (Group 1 = 10), MR advancement and MR resection (Group 2 = 12), MR advancement and lateral rectus (LR) recession (Group 3 = 13), MR advancement, MR resection, and LR recession (Group 4 = 14). Success results and possible risk factors were investigated. Forty-nine patients with consecutive XT (21 female, 28 male) were enrolled in the study. The mean age of overall patients was 22.97 years at surgery for consecutive XT. The groups did not display significant differences in terms of surgery ages, gender, refraction values, visual acuity, amblyopia, inferior oblique overaction, limitation of adduction, surgical success rates, and follow-up time (p > 0.05). Patients of Group 4 had larger preoperative and postoperative deviation, while Group 1 had smaller (p < 0.05). The surgical success rates of Groups 1, 2, 3, 4 were 90%, 75%, 76.9%, and 50%, respectively (p = 0.192). Statistically, no factor was found to be effective in surgical success rates (p > 0.05). Surgical treatment of consecutive XT is successful in most of the patients with numerous surgical options performed on a single eye in a single session. Patients, particularly with a high amount of deviation should be warned about the possibility of additional surgery.

Congenital ocular counter-roll: a review of cases treated exclusively by ophthalmologists.

To review the demographics, clinical manifestations, and surgical experiences of patients with congenital ocular counter-roll, whose treatments were performed exclusively by ophthalmologists. A retrospective review was conducted consisting of patients who received strabismus surgery between 2017 to 2019. Patients with obvious ocular counter-roll were included. A total of 7008 patients who received strabismus surgery, 28 (12 males, 16 females) were diagnosed as congenital ocular counter-roll, accounting for 0.40%. All patients were initially misdiagnosed: 21 patients were misdiagnosed as superior oblique palsy (SOP), 3 as inferior oblique overaction, 2 as dissociated vertical deviation (DVD), 1 as superior oblique overaction with A-pattern exotropia, and 1 as medial rectus palsy. The mean±SD age was 12.4±9.4y (range 2.5-36y). The most common clinical findings included ocular counter-roll, vertical deviation or vertical deviation combined with outward deviation and head tilt. At follow-up, an excellent surgical result was achieved in 20 patients. Preoperative horizontal deviation of 26±24 prism diopter (PD) and vertical deviation of 18±12 PD were reduced to 0±12 PD (P=0.0001) and 3±4 PD (P=0.001), respectively. Congenital ocular counter-roll is a rare supranuclear vertical strabismus caused by congenital abnormalities involving vestibule-ocular reflex pathways. In addition to ocular counter-roll, the most salient clinical features included, but are not limited to, hyperdeviation, outward deviation, overelevation in adduction and head tilt.

Electron Microscopic and Histopathological Study of the Overacting Inferior Oblique Muscle of the Human Eye

ABSTRACTBackground: Inferior oblique muscle overaction is a common disorder that has a correlation with the anatomical changes of the muscle itself. The changes differ according to the grade of the overaction.Objective: To correlate between the histopathological alternations of the inferior oblique muscle and the different degrees of clinical overaction.Patients and methods: Ten biopsies from inferior oblique muscles were taken during the surgery of strabismus after determining the clinical degree of the overaction. One muscle biopsy was taken during enucleation surgery and considered as a control. All biopsies were examined by light and transmission electron microscopes.Results: By light microscopy, grade II and grade III inferior oblique overaction showed many histopathological findings as muscle fibers degeneration, variable size of muscle fibers, nerve bundles hypertrophy and fibro-fatty infiltrations. Grade III inferior oblique overaction showed fibrosis of perimysium and endomysium, mononuclear infiltration and fatty infiltration. By transmission electron microscopy the muscle fibers showed increased mitochondrial number and mitochondrial variability in shape and size, also showed increased vacuoles and fat droplets.Conclusion: Histopathological alternations in the inferior oblique muscle correlate to the clinical grades of the muscle overaction.

Effect of inferior oblique muscle belly transposition on versions and vertical alignment in primary position.

To evaluate the effect of inferior oblique muscle belly transposition (IOBT) on vertical deviation (VD) in primary position and inferior oblique overaction (IOOA). Twenty-eight patients who underwent unilateral IOBT for mild hypertropia (≤ 10△) due to unilateral IOOA were included. Surgical results regarding the correction of hypertropia, IOOA, and fovea disc angle (FDA) were analyzed and compared between groups A (VD ≤ 5△) and B (5△ < VD ≤ 10△). IOBT showed an overall reduction of 5.86△ (± 2.24△) of primary position VD, a mean correction of 1.00 (± 0.27) of IOOA, and an average change of 1.83° (± 3.02°) of FDA. The surgical success rate of IOBT for VD correction and IOOA elimination in all patients was 68% and 71%, respectively. The correction of VD was correlated with preoperative VD significantly (r = 0.86, p < 0.001). Consistently, IOBT demonstrated comparable efficacy in reduction of VD between group A and group B (p = 0.507). Furthermore, the two groups were comparable in the success rates for correcting VD and IOOA (both p > 0.05). None of the patients developed consecutive hypotropia, postoperative contralateral IOOA, or anti-elevation syndrome postoperatively. IOBT achieved satisfactory outcomes in patients with mild primary position VD (≤ 10△) that is associated with unilateral IOOA, without any risk of overcorrection of VD and contralateral IOOA for a follow-up period of up to 12months. This procedure is considered effective and safe alternative for weakening the IO in patients with appropriate surgical indications.

Inferior Oblique Recession with 5 mm Loop to Correct Vertical Deviation and Inferior Oblique Overaction Secondary to Superior Oblique Palsy

ABSTRACT Purpose: To evaluate the effect of augmented inferior oblique recession (recession +5 mm loop) on the vertical deviation in primary position (PP) and the inferior oblique overaction (IOOA) in patients with unilateral congenital or acquired superior oblique palsy. Patients and methods: The medical records of patients who underwent unilateral inferior oblique recession with 5 mm loop during 2012 and 2019 were retrospectively reviewed. All patients had small to moderate manifest or intermittent hypertropia in PP and overaction of the inferior oblique muscle of +2 or +3 in lateral gaze. Patients who had combined inferior rectus surgery of the contralateral eye or who had previous vertical muscle surgery were excluded. Results: A total of 26 patients were included. Of these, three patients had combined horizontal muscle surgery. In 22 patients, the superior oblique palsy was congenital or longstanding, in 4 it was acquired and stable for more than 9 months. The mean preoperative vertical deviation in PP at distance and near was 14.7Δ and 11.2Δ, respectively. The mean postoperative vertical deviation was 5.7Δ and 4.1Δ after a mean follow-up of 19 months. The IOOA improved in all patients, 16 patients had an improvement of +2 and 10 patients had an improvement of +1. Conclusion: Inferior oblique recession with a 5 mm loop is a simple and quick technique to correct small to moderate hypertropia in primary position and inferior oblique overaction in contralateral gaze in patients with congenital, longstanding or acquired superior oblique palsy without risk of overcorrection.