Muscle path length in horizontal strabismus.

BACKGROUND: Sarcomere adaptation has been proposed as a mechanism for the adjustment of rectus muscle length in regulating binocular alignment. The purpose of this study was to investigate whether horizontal rectus muscle paths have abnormal lengths in subjects with intermittent or alternating strabismus. METHODS: High-resolution, surface coil magnetic resonance imaging was obtained in 2 mm thick axial planes in strabismic patients who had not undergone prior surgery and normal control subjects. The lengths of horizontal rectus muscle paths were measured digitally in central gaze for the fixating eye only and compared. RESULTS: A total of 12 strabismic subjects and 13 controls were included: 8 subjects had esotropia averaging 30(Δ), and 4 had exotropia averaging 47(Δ). The sample had 80% power to detect muscle path length changes of at least the typical surgical doses appropriate to strabismus surgery for correction of the mean deviations in each group, had such changes existed. Mean (± standard deviation) medial rectus path length was 35.0 ± 4.1 mm in controls, not significantly different from 36.3 ± 1.7 mm in exotropia (P = 0.56) or 35.8 ± 2.9 mm in esotropia (P = 0.62). Mean lateral rectus path length in controls was 35.7 ± 4.0 mm, not significantly different from the values of 39.6 ± 3.8 mm in exotropia (P = 0.09) and 37.8 ± 3.3 (P = 0.19) mm in esotropia. CONCLUSIONS: Horizontal rectus muscle path lengths are not significantly abnormal in commonly encountered intermittent or alternating esotropia and exotropia.

Risk factors influencing the outcome of strabismus surgery following retinal detachment surgery with scleral buckle.

PURPOSE: To determine factors associated with surgical success in patients undergoing strabismus surgery after retinal detachment repair with scleral buckle. METHODS: The medical records of consecutive patients who underwent strabismus surgery after repair of retinal detachment with scleral buckle were retrospectively reviewed. A successful "motor" outcome was defined as horizontal deviation <10(Δ) and vertical deviation <4(Δ) in the primary position; successful "sensory" outcome was no diplopia in the primary position. Various factors such as removing the scleral buckle at the time of strabismus surgery, the macula structural status, size of the preoperative deviation, presence of restriction to passive movement, and whether the eye with the scleral buckle was the operated eye were compared among groups based on motor success. RESULTS: A total of 25 patients were included. The overall motor success rate was 72% after 1.8 ± 0.9 operations, with 62% of patients diplopia free in the primary position. Horizontal deviation <10(Δ) (P = 0.005) and minimal restriction on forced duction test were associated with motor success after the first surgery (P = 0.05). Partial or entire scleral buckle removal (n = 15) and fellow-eye surgery were not significantly correlated with motor success in our cohort. There were no retinal redetachments after scleral buckle removal. CONCLUSIONS: A small preoperative horizontal deviation, and minimally restricted ocular rotations were associated with better results. Removing the scleral buckle did not improve results.

Avastin treatment reduces retinal neovascularization in a mouse model of retinopathy of prematurity.

PURPOSE: This study was designed to evaluate the effect of one intraperitoneal (IP) injection of bevacizumab (Avastin) on the severity of oxygen-induced retinopathy (OIR) in a mouse model. MATERIALS AND METHODS: Twenty-eight eyes of 14 mice with OIR were studied. There were nine mice in the bevacizumab-treated group (study group) and five mice in the saline-treated group (controls). The mouse OIR model consisted of a 5-day exposure to 75% oxygen. On postnatal day 12 (P12), Avastin 2.5 mg/kg was administered IP to the study group and 2.5 mg/kg normal saline was administered IP to the controls. All 14 mice underwent fluorescein angiography of the retinal vasculature on P17 and the following parameters were scored (Modified Retinopathy Scoring System, MRSS): blood vessel growth, formation of blood vessel tufts, extraretinal neovascularization, degree of central constriction, and tortuosity of vessels. In addition, the neovascular vessels were quantified on the hematoxylin and eosin (H&S)-stained paraffin sections of the eyes in a masked fashion. RESULTS: The MRSS score in the Avastin-treated mice was significantly lower than that of the saline-treated mice (3.06 ± 1.63 versus 7.1 ± 2.01, respectively, p = 0.0021). The neovascularization count was also significantly lower in the study group (3.44 ± 1.81 versus 9.34 ± 3.23 for the controls, p = 0.0013). CONCLUSIONS: IP Avastin treatment reduced the extent of oxygen-induced retinopathy in a mouse model of retinopathy of prematurity.

The effect of thalidomide on neovascularization in a mouse model of retinopathy of prematurity.

PURPOSE: Abnormal angiogenesis is the hallmark feature of retinopathy of prematurity (ROP), and contributes to the severe visual loss that accompanies this disease. Thalidomide is a well-known anti-angiogenic drug. We tested the assumption that injection of intraperitoneal thalidomide could reduce the severity of oxygen-induced retinopathy (OIR) in a mouse model. METHODS: Forty-three baby wild type mice were used in this study. The mouse model of oxygen-induced retinopathy consisted of a 5-day exposure to 75% oxygen from postnatal day 7 to 12 (P12) followed by 5 days in room air (relative hypoxia). Control mice were those with normally developing retinal vasculature exposed to room air from birth until postnatal day 17 (P17). Thalidomide (200 mg/Kg) was administered daily intraperitoneally to control and ROP mice in two protocols: (1) from P12 to P16, and (2) from P11 to P15 . Fluorescein-conjugated dextran angiography of retinal vasculature was performed on P17, and retinal whole mounts were prepared to score features of retinopathy. The parameters that were scored in a masked fashion included blood vessel growth, blood vessel tufts formation, extra retinal neovascularization, degree of central constriction, and tortuosity of vessels. These parameters constitute the Modified Retinopathy Scoring System (MRSS). In addition, quantification of the number of blood vessel tufts was performed in a masked fashion with hematoxylin & eosin (H&S) staining of paraffin-embedded eye sections. RESULTS: The retinopathy score by MRSS in the thalidomide treated mice was similar to that of untreated mice that were exposed to oxygen (9.3 +/- 1.9 vs 10.15 +/- 1.6; p = 0.21). The neovascularization count was also similar between the two groups (10.4 +/- 5.6 vs 9.6 +/- 4.8; p = 0.56). In the control group left in the room air, the retinopathy score was 0.19 +/- 0.37 (p = 0) and the neovascularization count was also very low (2.92 +/- 2.14; p = 0). CONCLUSIONS: Although thalidomide might have a proven anti-angiogenic and anti-inflammatory effect, our model did not show a significant effect on the retinopathy. The reason might be an ineffective level of the drug in the retina due to ineffective metabolism of the drug, or due to blockage of the drug by the blood-retina barrier, or the involvement of other factors besides those influenced by thalidomide in the process.

COL11A2 mutation associated with autosomal recessive Weissenbacher-Zweymuller syndrome: molecular and clinical overlap with otospondylomegaepiphyseal dysplasia (OSMED).

Autosomal recessive Weissenbacher-Zweymuller syndrome (WZS) is a skeletal dysplasia characterized by rhizomelic dwarfism and severe hearing loss. Mutations in the COL11A2 gene have been implicated in causing the autosomal dominant form of this syndrome as well as non-ocular Stickler syndrome and the autosomal recessive syndrome otospondylomegaepiphyseal dysplasia (OSMED). In a consanguineous Bedouin tribe living in Southern Israel, five individuals affected by autosomal recessive WZS were available for genetic analysis. Homozygosity of a mutation in the COL11A2 gene was found in all affected individuals. This finding lends molecular support to the clinical notion that autosomal recessive WZS and OSMED are a single entity.