Clinical characteristics and surgical outcomes of isolated inferior rectus palsy

Aim As isolated inferior rectus muscle (IRM) palsy represents a rare clinical entity, very limited information is available on this condition. The aim of this report was to elucidate the etiology, clinical characteristics and surgical outcomes of isolated IRM palsy. Methods Isolated IRM palsy cases who underwent surgical treatments at the Zhongshan Ophthalmic Center, Sun Yat-sen University, China over the period from January 2008 to June 2019 were reviewed retrospectively. Data evaluated from these cases included their etiology, ocular alignment, ocular motility, surgical procedures and surgical outcomes. Results A total of 61 patients (40 males, 21 females) were included in this review. Their mean ± SD age was 27.21 ± 16.03 years (range: 2 to 73 years). In these cases, 32 (52.5%) involved traumatic injury, 28 (45.9%) congenital hypoplasia or absence of inferior rectus and 1 (1.6%) with thyroid ophthalmopathy. The right eye was affected in 33 patients (54.1%), the left in 24 patients (39.3%), and both eyes in 4 patients (6.6%). The main clinical presentations consisted of hypertropia of the affected eye, motility limitation in abduction and depression and incyclotropia. After treatment consisting of various surgical approaches, including muscle repair or resection of the affected inferior rectus, recession of ipsilateral superior rectus, elongation of contralateral superior oblique and partial transposition of the horizontal rectus, the isolated IRM palsy was rectified in 49 patients (80.4%) with one surgery, while 11 cases (18.0%) required two surgeries and 1 case (1.6%) needed three surgeries. Finally, 52 patients (85.2%) showed a complete recovery, 6 (9.9%) improved and 3 (4.9%) experienced a surgical failure. Conclusion The main etiologies of isolated IRM palsy involved traumatic injury and developmental events. Overall, surgical outcomes of the various approaches employed were quite effective.

Quantitative evaluation of activity of thyroid-associated Ophthalmopathy using short-tau inversion recovery (STIR) sequence

Objective Quantitatively staging TAO using MRI remains limited. Our study aims to identify the cut-off signal intensity value for staging TAO using STIR sequence scan. Methods Between June 2018 and July 2020, a number of 51 patients with TAO (102 eyes) and 19 volunteer controls (38 eyes) were recruited. The clinical and biochemical parameters were measured in each patient. Disease activity was diagnosed based on the Clinical Activity Score (CAS). The signal intensities of extraocular muscles were scanned using short-tau inversion recovery (STIR) sequences from MRI. Results Compared to the inactive TAO patients and the controls, the signal intensity ratios (SIRs) of the superior rectus, inferior rectus, medial rectus, lateral rectus on STIR images were significantly increased in the active TAO patients. After adjustment for age and smokers, the SIRs of four extraocular muscles showed strong associations with CAS. By receiver operator characteristic (ROC) curve analysis, all four muscle SIRs demonstrated good efficiency for predicting disease activity [area under curve (AUC) 0.75–0.83, all P < 0.01]. The identified cut-off SIR values were further validated in a new group of TAO patients (30 eyes) enrolled between September 2020 and January 2021. The cut-off SIR value of > 2.9 in the inferior rectus showed optimal diagnostic value for staging the active TAO. Conclusions the signal intensity of extraocular muscles on STIR sequence was a good predictor for TAO activity. A cut-off SIR value of > 2.9 in the inferior rectus could be applied to evaluate the active stage of TAO.

Comparative Study of Outcomes by Surgical Procedures and Monocular Elevation Deficiency Syndrome in Indian Population

Introduction:Monocular elevation deficiency syndrome (MEDS) is a monocular elevation deficiency in abduction and adduction characterised by the hypofunction of superior rectus (SR) and inferior oblique muscles. Only a limited number of studies are published on the management of this problem. Herein, the indications and types of surgery for monocular elevation deficiency syndrome are reported.Methods: In this retrospective cohort study, all MEDS patients reported during 2010 to 2020 were retrieved from Electronic Medical Records after approval from the Hospital Ethical Committees. The data were exported in a pre-tested online format. The demographic and clinical information and data of surgeries, including strabismus and ptosis, were reported. The follow-up data were collected in a specific format. Strabismus was managed using Knapp procedure, Inferior Rectus recession and a combination of both approaches. Ptosis was corrected by Levator Palpebral Superioris (LPS) resection and brow suspension. The data were analysed using SPSS 22 based on descriptive analysis and cross-tabulation.Results: The cohort consists of 62 cases (females 26, males 36) of patients with mean age 17.00±12.31 years 40/62 cases comprised the paediatric age group. Knapp was carried out in 39, IR recession was carried out in 35, and combined Knapp+IR recession was performed in 17 cases based on FDT and FGT data. The comparative study found significant difference amongst these techniques (P=0.04). Ptosis correction was carried out by LPS resection in 21 and brow suspension in 23 cases depending on LPS function. This comparative study did not find any significant difference in the results (P=0.234).Conclusion: MEDS is a rare disease with various clinical features. The surgical management of strabismus may have more success for the combined technique than for those applied alone.

STRABISMUS MANAGEMENT AFTER ORBITAL BLOWOUT FRACTURE

Orbital floor fractures (OBF) account for 40% of mid-facial injuries and are therefore the most common of all trauma injuries in this region. The post-treatment complication that often follows orbital floor repair is residual diplopia or 1 persistent diplopia and is seen in 86% of the OBF cases. The causes for persistent diplopia can be varied and is often related to the degree of inflammation, trauma to 2 musculature, fat or nerves and surgical timing. Some of the common causes of the same are - malpositioning of the globe, fibrosis of the inferior fibro fatty muscular complex following trauma, direct damage to an extraocular muscle (commonly inferior rectus muscle), local injury to a motor nerve, ischemia (or compartment syndrome), iatrogenic damage during reconstructive surgery or entrapment under improperly placed alloplastic material. Our case report mentions a rare case of persistent vertical diplopia even after successful repair of orbital blowout fracture. A 15-year-old male patient following a road traffic accident presented with persistent headache and vertical diplopia. The patient was evaluated by a oral maxillofacial surgeon and a presumptive diagnosis of a case of large orbital floor fracture with entrapment of inferior rectus muscle was made which was confirmed on CT Scan. He was managed surgically by reduction of the fracture and fixation with a titanium mesh. 2 weeks post-surgery he reported to the squint clinic with complaints of persistent double vision. On comprehensive ocular examination, it was found that patient had vertical diplopia with limitation of infraduction in the left eye with negative FDT, on re-evaluation of MRI scans with 1 mm cuts, a partial left inferior rectus tear was seen and documented as the cause of persistent diplopia. Patient was treated conservatively by prescribing prismatic glasses with fusional exercises. After 6 months of follow up, the patient was relieved of diplopia in primary position but there was a residual hypotropia in downgaze for which he was prescribed prisms only for downgaze.

Correlation between Thyroid-stimulating Antibody Level Change and Extraocular Muscle Thickness Change in Thyroid Eye Disease

Purpose: To investigate the changes in extraocular muscle thicknesses by variations in the thyroid stimulating antibody (TSAb) level in patients with thyroid eye disease (TED).Methods: A total of 67 TED patients were enrolled. They were divided into two groups: an experimental group with clinically significant elevated TSAb levels (≥140 IU/L) and a control group (TSAb <140 IU/L). All of the lateral, medial, superior, and inferior rectus muscle thicknesses were measured with the aid of anterior segment optical coherence tomography (OCT). The average thicknesses for both eyes were recorded for each patient based on the values measured at the ends of the muscles (which become vertically thinner from the points of tendon attachment). We measured changes in TSAb levels and extraocular muscle thicknesses after two follow-up periods and sought correlations among these parameters.Results: At the initial visits, the inferior rectus muscle thickness was positively correlated with the TSAb level in the experimental group (p = 0.045, r = 0.478). None of the medial, superior, or lateral rectus muscle thicknesses were so correlated. On follow-up, the variation in TSAb level correlated negatively with changes in lateral rectus muscle thickness (p = 0.038, r = -0.357). The superior rectus muscle thickness tended to be negatively correlated with the TSAb level, but statistical significance was not attained (p = 0.146, r = -0.669). The thicknesses of the inferior and superior rectus muscles did not change over time.Conclusions: In TED patients, TSAb variations seem to reflect the extent of periorbital tissue edema, thus correlating negatively with especially lateral rectus muscle thickness changes.

Absent Bell’s phenomenon in patients with thyroid eye disease

Background To investigate the incidence of absent Bell’s phenomenon (BP) and the relationship between absent BP and inferior rectus muscle hypertrophy and other clinical features in patients with thyroid eye disease (TED). Methods A total of 104 patients who were first diagnosed with TED between January and December 2014 were included. Inferior rectus muscle area and associations with clinical features of TED and thyroid function test including thyroid specific antibodies were compared between patients with TED with and without BP. The volume of the inferior rectus muscle was calculated by adding up all the cross-sectional areas measured on sagittal CT images. Results Among the 104 patients, 14 had absent BP (13.5%), 12 with bilateral and two with unilateral. There was no significant difference in thyroid function test, presence of TSIs, exophthalmos, or volume of inferior rectus muscle measured in CT scans (P > 0.05). Incidence of diplopia, elevation limitation, and upper eyelid retraction were risk factors of absent BP in TED patients (by logistic regression analysis, P < 0.05). Conclusions Inferior rectus muscle hypertrophy was not the cause of absent BP in TED patients. Fibrosis and tightening of the inferior rectus muscle, lower eyelid, and surrounding orbital tissues, rather than inferior rectus muscle hypertrophy, might be related to absent BP in TED patients.

Comparative Study of Outcomes by Surgical Procedures and Monocular Elevation Deficiency Syndrome in Indian Population

Introduction: Monocular elevation deficiency syndrome (MEDS) is a monocular elevation deficiency in abduction and adduction characterised by the hypofunction of superior rectus (SR) and inferior oblique muscles. Only a limited number of studies are published on the management of this problem. Herein, the indications and types of surgery for monocular elevation deficiency syndrome are reported.Methods: In this retrospective cohort study, all MEDS patients reported during 2010 to 2020 were retrieved from Electronic Medical Records after approval from the Hospital Ethical Committees. The data were exported in a pre-tested online format. The demographic and clinical information and data of surgeries, including strabismus and ptosis, were reported. The follow-up data were collected in a specific format. Strabismus was managed using Knapp procedure, Inferior Rectus recession and a combination of both approaches. Ptosis was corrected by Levator Palpebral Superioris (LPS) resection and brow suspension. The data were analysed using SPSS 22 based on descriptive analysis and cross-tabulation.Results: The cohort consists of 62 cases (females 26, males 36) of patients with mean age 17.00±12.31 years 40/62 cases comprised the paediatric age group. Knapp was carried out in 39, IR recession was carried out in 35, and combined Knapp+IR recession was performed in 17 cases based on FDT and FGT data. The comparative study found significant difference amongst these techniques (P=0.04). Ptosis correction was carried out by LPS resection in 21 and brow suspension in 23 cases depending on LPS function. This comparative study did not find any significant difference in the results (P=0.234).Conclusion: MEDS is a rare disease with various clinical features. The surgical management of strabismus may have more success for the combined technique than for those applied alone.

Simulation of complex strabismus surgical procedures on goat eyes

Purpose: To describe the possibility of complex strabismus surgical simulation on goat eyes. Methods: The goat eyes were procured from local slaughterhouse with retained extra ocular muscle tissues. The obtained eyes were inspected for globe integrity, muscle quality, muscle length, and the surrounding teno-conjunctival layers. The included eyes were then segregated for surgical simulation based on their insertion and orientation (as oblique or recti), and they were mounted on a mannequin head, with a fixation suture at free end to simulate the resting tension. Additionally, as per necessary, extra muscles were also transplanted along desired sites to simulate human extra ocular muscle anatomy. Results: The inferior oblique, superior oblique, and all other four recti were successfully simulated in varying proportions in more than 50 eyes. Primarily, by simulating the lateral rectus, inferior rectus, and the inferior oblique muscle, staged weakening procedures of inferior oblique were successfully practiced (Fink’s recession, Park’s recession, Elliot and Nankin procedure, total anterior positioning, and antero-nasal trans-position or Stager’s procedure). Similarly, by simulating superior rectus, inferior rectus, lateral rectus, and the medial rectus muscles, half width transposition, full width transposition, and other complex procedures were practiced (Knapp’s procedure, augmented Knapp’s, Nishida’s procedure, Faden operation, and Y splitting procedure). Furthermore, by simulating superior oblique and the superior rectus muscles, superior oblique tuck, posterior tenectomy, loop tenotomy, and Harada Ito procedures were successfully practiced. Conclusions: On goat eyes, the complex strabismus surgical procedures can be successfully simulated and practiced after re-organizing the existing muscles in different patterns.

A rare case of early massive monomuscular fibrosis causing severe unilateral euthyroid Graves’ ophthalmopathy in a smoker patient with dyslipidemia

BackgroundGraves’ ophtahlmopathy (GO) is an autoimmune manifestation of orbit affecting about 25% of patients with Graves’ disease (GD). Autoreactive T cells involved in thyroid autoimmunity can recognize the thyroid stimulating receptor (TSHr) expressed in orbit tissues of GO patients. Clinical manifestations of GO are rather different depending of the presence of some risks factors as smoke, hyperthyroidism duration, age, biological activity of anti TSHr antibodies (TSH-R-Ab) and metabolic diseases.Case presentation:here we present a rare case of euthyroid single muscular GO in a 50 years old patient, he was smoker and had dyslipidemia from several years. The patient experienced a very rapid and severe depression of ocular motility of the right eye that causes an uncorrectable and constant diplopia severely affecting his quality of life. He was euthyroid and TSH-R-Ab plasmatic levels were only slightly elevated. Intravenous corticosteroids pulse therapy was partially effective and two rounds of wall orbital surgical decompression was necessary. A massive mono-muscular fibrosis was evidenced by biopsy of right inferior rectus muscle.Conclusionssevere unilateral, mono-muscular GO in a euthyroid Graves’ patient was found to be sustained by rapid and massive fibrosis of the inferior rectus muscle of right orbit, the clarification of pathogenetic mechanisms of these GO clinical forms requires further studies.