The current data on various aspects of Brown syndrome are limited and sporadic. This review provides a coherent and comprehensive review of basic features, etiology, classification, differential diagnosis, and different management strategies of patients with Brown syndrome. In this topical review, PubMed, Scopus, and Google Scholar search engines were searched for papers, published between 1950 and January 2023 based on the keywords of this article. The related articles were collected, summarized, categorized, assessed, concluded, and presented. Brown syndrome is identified by restricted passive and active elevation of the eye in adduction. The condition is divided into congenital and acquired causes. The clinical features result from a restricted motion of the superior oblique tendon sheath through the trochlea while trying to look up in adduction. The newest explanation of the underlying pathophysiology has been explained as the presence of a fibrotic strand in the superior oblique muscle tendon with variable insertion sites which creates various elevation deficits seen in Brown syndrome. The most common clinical features include the presence of an abnormal head posture, V-pattern strabismus, and hypotropia in the primary position. Management of Brown syndrome includes watchful observation, surgical, and non-surgical procedures. Some cases might resolve spontaneously without any intervention; however, some acquired cases might require systemic and/or intra-trochlear steroid administration to treat the underlying causes. Surgical procedures such as superior oblique tenectomy and using a silicon tendon expander are indicated in the presence of hypotropia and significant abnormal head posture in the primary position.

Surgical innovations in strabismus provide opportunities to improve visual function, eye alignment, and cosmesis in rare pediatric ophthalmological conditions. Monocular elevation deficiency is a rare and multifactorial disease in which the affected eye is equally limited in terms of elevation during adduction and abduction. We aimed to present a novel procedure for the treatment of acquired monocular elevation deficiency using the paretic superior rectus muscle as a globe suspender to resolve hypotropia. We report the case of an eight-year-old girl with left eyelid ptosis and hypotropia two months after draining a left orbital abscess. Left inferior rectus muscle recession was performed at five years, with residual left hypotropia. Ophthalmological examination revealed a best-corrected visual acuity of 20/20 OD and 20/100 OS. Severe left eyelid ptosis and poor levator function were also observed. Extraocular motility showed left hypotropia of 40 prism diopters with the left superior rectus muscle under action (-4) in the adduction and abduction positions. A force duction test negative for restrictions on the inferior rectus muscle was performed intraoperatively. To reduce the risks of the Knapp procedure, the left superior rectus muscle was split into medial and temporal halves. Double-armed sutures were secured in half, and the halves were detached from the sclera. The medial and temporal halves were reattached anteriorly to the medial and lateral rectus insertions, respectively. Eight weeks after surgery, the patient had nine prism diopters of hypotropia in the primary gaze. Ten weeks after surgery, there was no change in visual acuity. In the cover test, the patient exhibited residual left hypotropia of nine prism diopters with a restriction (-4) of elevation in adduction and abduction. The parents were pleased with the satisfactory cosmetic outcomes, and postoperative clinical photographs of the patient showed improved hypotropia and persistent minimal elevation of the left eye during adduction and abduction. Superior rectus muscle splitting and vertical transposition to the medial and lateral rectus could be safer and simpler alternatives to the Knapp procedure and may offer a lower risk of anterior segment ischemia. Further studies are required to confirm these findings.

UNASSIGNED: Understanding the refractive profile, amblyopia prevalence, binocular status, and head position in patients with Brown syndrome help clinicians become more familiar with this syndrome.
UNASSIGNED: Brown syndrome is identified as an active and passive restricted elevation of the eye in adduction. There is little information on clinical features, including refractive status, amblyopia, abnormal head posture (AHP), and types of deviation in these patients.
UNASSIGNED: This study retrospectively evaluated records of 100 Brown syndrome patients from 2015 to 2022 at Farabi Eye Hospital, Iran.
UNASSIGNED: The mean age was 6.99 ± 6.33 years, including 48 (48%) males. A congenital source was found in 74 (74%) and 96 (96%) patients had unilateral involvement. The mean CDVA for the affected and non-affected eyes were 0.05 ± 0.11 and 0.03 ± 0.06 logMAR, respectively (P = 0.31). In unilateral cases, hyperopia, myopia, and emmetropia were observed in 55 (57.29%), 2 (2.08%), and 39 (40.63%) affected eyes, respectively. The most common type of deviation was pure hypotropia, which was found in 53 (53%) cases, followed by \'combined exotropia and hypotropia\' observed in 26 (26%) patients. The mean angle of hypotropia and horizontal deviation in the primary position at distance was 12.10 ± 8.50 and 8 ± 13.20 prism dioptre, respectively. A V-pattern was found in 76 (76%) patients. Amblyopia was observed in 13 (21.67%) of 60 cooperative patients, and AHP was noticed in 66 (66%) patients, in which \"combined chin up and contralateral face turn\" was the most common type.
UNASSIGNED: About 75% of cases were congenital, 50% had pure hypotropia, 75% showed V-pattern, 20% had amblyopia, and AHP was observed in 67% of patients. The remarkable prevalence of amblyopia alongside the high occurrence of AHP should alert clinicians to carefully assess patients with Brown syndrome for sensory fusion and amblyopia.

OBJECTIVE: To report the case of a congenital restrictive strabismus with a contralateral enlargement of extraocular muscles.
METHODS: The clinical presentation, findings, and postoperative outcomes of a 4 years old boy referred to evaluation for presenting a left eye deviation since birth are detailed.
CONCLUSIONS: A unilateral congenital restrictive strabismus (congenital hypotropia and esotropia) can be the cause of contralateral secondary enlarged extraocular muscle and It must be included in the differential diagnosis.

OBJECTIVE: To evaluate the outcome of fenestration of the vertical rectus muscles in correcting vertical deviations.
METHODS: A retrospective chart review was conducted on patients who underwent fenestration surgery on the superior rectus (SR) or inferior rectus (IR) muscles. Ductions, versions, angle of deviations before and after surgery, and surgical details were analyzed. Success was defined as vertical alignment within 4 PD of orthophoria.
RESULTS: Nineteen patients were identified. The mean age of the patients was 19.3 ± 13.1 (range; 4 to 48) years. The mean follow-up was 6.5 ± 2.7 (range, 3 to 12) months. Eleven patients presented with dissociated vertical deviation (DVD), 2 patients with sensory hypertropia, and 6 patients with sensory hypotropia. Fourteen patients had concomitant horizontal muscle surgery. The mean change of the angle of deviation was 13 ± 3 (range, 8 to 20) PD after SR fenestration. and 12 ± 2 (range; 10 to 15) PD after IR fenestration. There was a significant improvement in the post operative angle of deviation in both groups (P value <0.001). Success was achieved in 10 (77%) of patients who underwent SR fenestration and in all patients underwent ir fenestration. Only one patient in the IR group developed a 1-mm lower lid retraction.
CONCLUSIONS: Fenestration of the vertical rectus muscles is an effective and safe method for correcting vertical deviations. We recommend increasing the amount of fenstration in DVD to further improve the outcome.

Monocular elevation deficiency (MED) is characterized by unilateral limitation of supraductions, similar in adduction and abduction, in addition to hypotropia and ptosis. We describe a case of a 62-year-old woman with long-standing left ptosis who was initially operated with a frontal suspension technique. On subsequent examinations, a MED of that eye was found. The passive duction test was positive, so the inferior rectus was recessed. In addition, a modified Nishida technique was performed, consisting of the scleral anchorage of the superior edges of the rectus, medial and lateral, 12mm from the corneal limbus in the superonasal and superotemporal quadrants, respectively. Postoperatively, the left eye presented a minimal hypotropia of 3 PD. This modified technnique used here on the horizontal rectus muscles, turned out to be effective and safe for the correction of MED.

Monocular elevation deficiency (MED) is characterized by unilateral limitation of supraductions, similar in adduction and abduction, in addition to hypotropia and ptosis. We describe a case of a 62-year-old woman with long-standing left ptosis who was initially operated with a frontal suspension technique. On subsequent examinations, a MED of that eye was found. The passive duction test was positive, so the inferior rectus was recessed. In addition, a modified Nishida technique was performed, consisting of the scleral anchorage of the superior edges of the rectus, medial and lateral, 12mm from the corneal limbus in the superonasal and superotemporal quadrants, respectively. Postoperatively, the left eye presented a minimal hypotropia of 3 PD. This modified technnique used here on the horizontal rectus muscles, turned out to be effective and safe for the correction of MED.

UNASSIGNED: To study the effect of vertically transposing both horizontal eye muscles of one eye in the same direction on vertical strabismus.
UNASSIGNED: Retrospective analysis of 33 patients in whom vertical transposition of the medial and lateral rectus muscles was combined with a recession/resection or recession/plication procedure. Preoperative ocular alignment was compared with that 1 day and 3 months postoperatively.
UNASSIGNED: Mean preoperative vertical deviation was 7.8 ± 4.3 (median 7.5, range 3-25) prism diopters (PD) at distance and 7.8 ± 4.1 (7, 0-18) PD at near. Vertical transposition of the horizontal rectus muscles averaged 5.6 ± 1.6 mm and reduced the vertical deviation to 3.4 ± 4.2 PD (2, 0-16) at distance and 2.9 ± 3.7 PD (2, 0-14) at near. Mean effect on the vertical deviation was 0.9 ± 0.7 (0.8, -0.8 to 2.13) PD/mm at distance and 0.9 ± 0.9 (0.83, -1 to 3) PD/mm at near, it was similar in patients operated on for esotropia and for exotropia. The surgical effect on the horizontal deviation was 2.1 ± 1.1 PD/mm (distance) and 2.6 ± 1 PD/mm (near). Both the vertical and horizontal surgical dose correlated with the effect in a linear way, but the variability was greater for the vertical transposition.
UNASSIGNED: Vertical transposition of the horizontal rectus muscles in the same direction allows for correction of vertical strabismus. This procedure may be performed during primarily horizontal strabismus surgery, without operating on an additional extraocular muscle. The transposition distance correlates with the surgical effect but predictability of the effect is limited.

Monocular elevation deficiency is characterized by the inability to elevate one eye in abduction, adduction, and primary gaze. To date, various operations, including Knapp\'s procedure, have been used in the management of hypotropia associated with this condition. However, single muscle transposition has only recently been described as a feasible alternative, offering a number of advantages over other techniques. In particular, it reduces the risk of anterior segment ischemia and allows for an inferior rectus recession to occur simultaneously as is often required, thus avoiding the need for staged operations. It also facilitates a wider range of management options to correct for associated horizontal deviation. We present a case detailing the use of single muscle transposition in the management of monocular elevation deficiency and in doing so confirm the utility of this novel technique.

OBJECTIVE: To assess the efficacy of \"Yokoyama Procedure,\" on non-highly myopic patients with acquired esotropia and hypotropia.
METHODS: The study involved 10 eyes of 5 patients with eso-hypotropia. Inclusion criteria were acquired esotropic-hypotropic strabismus with lateral rectus inferior displacement and superior rectus nasal displacement confirmed by magnetic resonance imaging, refractive errors between ±6 D, and axial length < 27 mm. Range of full duction movements and maximum angles of abduction-sursumduction was measured in each eye before and after surgery. All patients underwent T1- and T2-weighted magnetic resonance imaging. The surgery was aimed at creating a junction between the muscle bellies of the superior and lateral rectus muscles. This junction was made approximately 14 mm behind the insertions using a non-absorbable mersilene 5/0 suture (Yokoyama procedure).
RESULTS: Mean patient age was 64.8 ± 4.8 years. The mean globe axial length was 25.4 ± 0.76 mm and a mean corresponding spherical equivalent refraction of -3.7 ± 1.7 D was observed. Eight eyes on 10 had mild limitation in abduction, while the remaining 2 had no limitation. Three out of 10 eyes showed a moderate limited sursumduction, 5 eyes were categorized as mild, and the remaining 2 had no limitation. No evident post-operative limitation was present in any eye, in both abduction and sursumduction (p < 0.01). Pre-operative esotropia and hypotropia were, respectively, 32 ± 11 prismatic diopters and 25 ± 5 prismatic diopters, and they were significantly reduced after surgery as 9 ± 1.7 prismatic diopters and 6 ±1 prismatic diopters (p = 0.043), respectively.
CONCLUSIONS: Yokoyama procedure is an effective, fast, reversible procedure to face eso-hypotropic acquired strabismus, even in patients with a clear magnetic resonance imaging displacement of superior and lateral rectus muscles, and absence of globe dislocation and of elevated myopia.