Intermuscular Membranes Research Articles

Efficacy of modified Park’s technique in the treatment of children with strabismus

Purpose: To investigate the efficacy of modified Park’s technique in children with strabismus.
 Methods: A total of 120 patients were recruited in the Department of Ophthalmology, Anhui Provincial Children's Hospital, Anhui, China between January 2019 and December 2021. The patients were divided into study and control groups comprising 60 patients each. Control group underwent rectus muscle adjustment suture using standard incision, while study group received modified Park’s technique, which involved intermuscular membrane incision and conjunctiva two-layer suture method. Various parameters such as perioperative indicators, tear film function, and patient satisfaction were assessed.
 Results: The study group had significantly lower intraoperative blood loss, duration of surgery and length of hospital stay (p < 0.01). Also, it showed significantly higher Schirmer’s time, tear film break-up time (TFBUT) time and significantly lower corneal staining score (p < 0.01). Satisfaction level was significantly higher in the study group compared to control group (p < 0.05). So also was clinical efficacy (91.67 %) compared to control group (83.33 %). Furthermore, study group exhibited significantly lower incidence of complications (5) compared to control group (11; p < 0.05).
 Conclusion: Enhanced Park’s technique improves perioperative indicators, tear film function, and satisfaction level; it also produces high efficacy and lower incidence of complications. This suggests that it might be a viable substitute for conventional treatment of children with exotropia. However, long-term follow-up data will be required to establish the superiority of this treatment strategy.

Effect of Limited Tenon Capsule and Intermuscular Membranes Dissection on the Outcome of Surgery in Patients with Horizontal Strabismus

ABSTRACTPurpose: The aim of the study was to evaluate the effect of limited dissection of Tenon capsule on the outcome of strabismus surgery.Methods: Patients between the ages of 2 and 50 years with pure horizontal strabismus were enrolled in a prospective study. Patients were divided into two groups: case and control as a non-randomized study. The method of operation was similar in both groups except for the amount of sheath Tenon dissection. In the control group the intermuscular connections and Tenon capsule were cut as much as possible. In the study group, Tenon capsule, 3-4 mm posterior to the location of the sutures over the muscle (recessed or resected), were cut and intermuscular connections remained intact.Results: The study enrolled 54 patients with 27 patients in each group. In both groups, after operation, regardless of the type of surgery, the angle of strabismus was reduced (P< 0.05). For patients who had undergone bimedial recession, the angle of strabismus was corrected to 2.6 ± 0.4 prism diopters per mm (PD/mm) of muscle recession in the case group, and 2.2 ± 0.9 in the control group (P=0.2). For patients who had undergone monocular recession and resection (R&R) for esotropia, the angle of strabismus was corrected 3.4 ± 0.3 PD/mm of muscle recession or resection in the case group, and 3.2 ± 0.2 in the control group (P=0.05). For patients who had undergone bilateral recession, the angle of strabismus was corrected 2.3 ± 0.2 PD/mm of muscle recession in the case group, and 2.2±0.2 in the control group (P=0.03). For patients who had undergone R&R for exotropia, the angle of strabismus was corrected 3.1 ± 0.5 PD/mm of muscle recession or resection in the case group, and 2.7 ± 0.3 in the control group (P=0.02).Conclusion: Connective tissue ensheathments, whether disturbed or removed, do not ultimately affect the success of the strabismus surgery.

Regional Anesthesia and Eye Surgery

Regional Anesthesia and Eye Surgery

Oculomotricidade e seus fundamentos

Partindo-se de um circuito esquemático relacionando os sistemas sensorial (visual binocular) e oculomotor, cujos defeitos em vias aferentes ou eferentes, ou de suas interações, explicam o aparecimento dos estrabismos e suas conseqüências, são examinados os fundamentos e referenciais da movimentação ocular. Apresentam-se os conceitos de eixos e planos, centro de massa e de rotação, definem-se os movimentos monoculares de translação e de rotação e os binoculares de versões e vergências. É também referida a função dos centros de comando para movimentos voluntários e reflexos, a dos núcleos oculomotores e a respectiva inervação aos músculos oculares externos. Numa segunda parte (fisiologia da musculatura ocular extrínseca) são comentadas as atividades de contração e relaxamento e a importância da lei de Sherrington. Voltando-se ao conceito de posição primária do olhar e dos referenciais das rotações, menciona-se a diversidade de vários sistemas de medidas. Em seguida, são analisadas as ações musculares rotacionais com bases no plano de ação muscular e na distribuição anatômica dos músculos, levando a resultados em posição primária do olhar e nas outras. Os efeitos de fáscias e membranas intermusculares são também comentados, terminando-se com a concepção moderna sobre as ações musculares (ação simultânea de todos os músculos em quaisquer das posições oculares). Com os condicionantes da lei de Hering, desenvolve-se o conceito de posições diagnósticas (das disfunções oculomotoras), diferentemente do clássico: os músculos são considerados em pares, de acordo às suas ações predominantes ___ horizontais (retos horizontais), verticais (retos verticais) ou torcionais (oblíquos). Em cada qual devem ser comparadas as ações em condições diametralmente opostas de fixação ocular e posições do olhar (por exemplo, supradextroversão na fixação com o olho direito e infralevoversão na fixação com o olho esquerdo, para comparação de ações dos músculos retos superior direito e inferior esquerdo, respectivamente). Também é analisada a influência das inclinações de cabeça sobre essas ações. O artigo termina examinando a relação sincinética entre a acomodação e convergência, a convergência proximal e as unidades dessas funções.

Partial and total tenotomy of superior oblique muscle

The results of 33 superior oblique (SO) posterior and total tenotomy procedures were reviewed in 30 years of 17 patients. Two patients required secondary surgery, and the chosen procedure was tenotomy of SO muscle at the nasal side of the superior rectus muscle, whereas the initial tenotomy of SO muscle could be graded based on the dissection of intermuscular membrane plus the tenotomy site.

Nuclear magnetic resonance tomography diagnosis of eye motility disorder in high-grade myopia for planning an eye muscle operation

This study was conducted to elucidate the etiology of the acquired, restrictive motility disorder in patients with severe myopia by magnetic resonance imaging (MRI) and intraoperative situs and to verify existing theories about strabismus to develop appropriate methods of eye muscle surgery. Thirty-five patients with unilateral or bilateral high-degree myopia and strabismus, i.e., axial length of the globe averaged 29.4 mm. Multiple coronal, transversal and parasagittal MRI planes were obtained using a Siemens Magnetom (SP 63) 1.5 Tesla MRI scanner (TR = 550 ms, TE = 15 ms; field of view = 21 x 21 cm; pixel matrix = 256 x 512; 3 acquisitions; slice thickness 2 mm; distance factor 0.25). In addition, in a dynamic MRI the patient had to fixate with the less restricted eye for 50 s in different gaze positions. All data were validated by measurements during strabismus surgery. Twenty normal orbits were studied in control MRI scans. The major MRI finding was dislocation of the lateral rectus in the anterior and midorbital region at an average of 3.4 mm into the temporocaudal quadrant in 13 cases with the typical eso- and hypotropia. This dislocation will reduce the abducting torque of the lateral rectus and create depressing and extorting torques. Two-anatomical explanations are possible: (1) increasing stretch of the lateral rectus because of temporocranial distension of the globe and inability of intermuscular membranes and pulleys to stabilize the path of the lateral rectus; (2) dehiscence of the lateral levator aponeurosis. The restrictive motility disorder was never caused by contact between the enlarged globe and the bones of the orbital apices. Until now, an abnormal path of recti EOMs has been known only in Duane's syndrome. Prior to strabismus surgery in patients with high-degree myopia, an orbital MRI scan may be useful. If misalignment of the lateral rectus is detected, the most important aim of eye muscle surgery is to normalize the pathological path of the lateral rectus. MRI morphometry in severe myopia may give additional information on the anatomy of the orbit and biomechanical mechanisms of strabismus. Our findings demonstrate the necessity of fixation-controlled MRI scans.

Effect of Severing the Check Ligaments and Intermuscular Membranes on Medial Rectus Recessions in Infantile Esotropia

The effect of severing the check ligaments and intermuscular membranes on the dose-response curve for medial rectus recessions in patients with infantile esotropia has not been previously studied by randomized assignment techniques using contemporary control and experimental groups and masked precautions. A prospective study of 101 patients was performed over an 8-year period. Patients were randomly assigned to either augmented or nonaugmented groups. In the former group, the medial check ligaments and intermuscular membranes were severed; in the latter group, no surgery was performed on the medial check ligaments or intermuscular membranes. Patients were postoperatively evaluated by an observer masked to group assignment. No difference in response to surgery was observed between the two groups at the time of evaluation, which took place, on average, 6 to 7 months after surgery. Severing the check ligaments and intermuscular membranes on patients with infantile esotropia undergoing medial rectus recessions does not appear to affect the dose-response curve.

Role of Tenon??s Capsule in Postoperative Restrictions

Management of all restricted strabismus cases is difficult and frequently will require two or more procedures. The prevention of these restrictions at the time of primary surgery is far more important. All tissue should be handled as gently as possible, with smooth or fine-tip forceps, avoiding large fixation devices. Sharp dissection is essential - tissue should not be torn but cut carefully and sharply with scissors under direct visualization. The conjunctival and Tenon's capsule incisions should not be made directly over the muscle; this will result in scarring of the muscle to Tenon's capsule or of Tenon's capsule to the muscle insertion stump, promoting restriction. The muscle should be isolated under direct visualization or inspected carefully after isolation, with great care taken not to incorporate any unnecessary Tenon's capsule in the muscle and to avoid the inferior oblique msucle on lateral rectus muscle surgery. A blind, deep sweep is completely contraindicated. The intermuscular membranes, check ligaments, and muscle foot plates must be completely severed, under direct visualization, well beyond the resection site in the course of a resection,and 5 to 8 mm. behind the insertion in the course of a recession. Complete hemostasis during the procedure and at its completion is essential; 2.5 percent phenylephrine and minimal cautery will help achieve this. Since cautery will result in a scar of Tenon's capsule to that area of the sclera, it should be used as little as possible. Phenylephrine 2.5 percent has been used safely with halothane anesthesia in many patients without significant arrhythmias. The secondary treatment of restriction is very difficult, whereas their prevention requires only good surgical technique and careful attention to detail.

Human eye movements following horizontal rectus muscle disinsertion.

Patient with long-standing exotropia had strabismus surgery performed using only topical anesthesia. During the surgical procedure, horizontal saccades were measured by electro-oculography. It was found that horizontal saccades were slowed from 240°/sec, preoperatively to 100°/sec following muscle disinsertion. Further saccadic slowing was noted when the disinserted muscle was held taut and was prevented from contracting. This decrease is attributed to limitation of the effective action of the disinserted muscle through posterior attachments to intermuscular membrane and fascia bulbi. Findings following disinsertion may resemble the ocular rotations and saccades noted after release of a suture in early postoperative period after strabismus surgery. Saccadic velocity measurements may be clinically useful in the diagnosis of this problem.

Fascia in relation to extraocular muscle surgery.

Fascial expansions to the lids and orbital wall do not arise directly from the rectus muscles as check ligaments. Instead, this fascia merges in the fornices with Tenon's capsule and subconjunctiva forming a tissue ring which encircles the globe. Incisions anterior to this fornix ring permit recession and resection under Tenon's capsule without disturbing fascial interrelations. Incisions into the fornices cause adnexal deformities. Tenon's capsule is easily elevated from the muscle sheaths which are separate structures continuous with anterior episcleral and intermuscular membranes. Integrity of the sheaths should be preserved. They are the primary source of fibroblasts for reattachment of tendons to the sclera. Fibroplasia from sheath defects causes adhesions.

Sensory block of the upper eyelid.

A SENSORY block of the upper eyelid can be achieved without loss of extraocular muscle function or distortion of lid tissues with a single, small, properly placed injection. This technique simultaneously blocks the frontal and lacrimal nerves at their point of divergence posteriorly in the orbit. It has been used in a variety of lid procedures, but finds its greatest value in ptosis surgery where retention of ocular motility permits ideal placement of the lid margin. Method Any of the usual anesthetic solutions may be used, preferably without the addition of hyaluronidase since this may permit some penetration of the anesthetic solution through the intermuscular membrane into the deeper orbital tissues. A 4-cm needle, about size 23 or 22, is introduced precisely at the midpoint of the upper lid just below the bony orbital margin. At this location, the needle is some distance lateral to the frontal nerve, reducing the