Rosália M. S. Antunes-Foschini

Effects of Recession versus Tenotomy Surgery without Recession in Adult Rabbit Extraocular Muscle

PURPOSE Surgical recession of an extraocular muscle (EOM) posterior to its original insertion is a common form of strabismus surgery, weakening the rotational force exerted by the muscle on the globe and improving eye alignment. The purpose of this study was to assess myosin heavy chain (MyHC) isoform expression and satellite cell activity as defined by Pax7 expression in recessed EOMs of adult rabbits compared with that in muscles tenotomized but not recessed and with that in normal control muscles. METHODS The scleral insertion of the superior rectus muscle was detached and sutured either 7 mm posterior to its original insertion site (recession surgery) or at the same site (tenotomy). One day before euthanization, the rabbits received bromodeoxyuridine (BrdU) injections. After 7 and 14 days, selected EOMs from both orbits were examined for changes in fast, slow, neonatal, and developmental MyHC isoform expression, Pax7 expression, and BrdU incorporation. RESULTS Recession and tenotomy surgery resulted in similar changes in the surgical EOMs. These included a decreased proportion of fast MyHC myofibers, an increased proportion of slow MyHC myofibers, and increased BrdU-positive satellite cells. Similar changes were seen in the non-operated contralateral superior rectus muscles. The ipsilateral inferior rectus showed reciprocal changes to the surgical superior rectus muscles. CONCLUSIONS The EOMs are extremely adaptive to changes induced by recession and tenotomy surgery, responding with modulations in fiber remodeling and myosin expression. These adaptive responses could be manipulated to improve surgical success rates.

Activated Satellite Cells in Medial Rectus Muscles of Patients with Strabismus

PURPOSE The goal of this study was to determine whether the medial rectus muscles of patients with a history of medial rectus underaction or overaction show alterations in the process of satellite cell activation when compared with normal age-matched control muscles. METHODS Medial rectus muscles were obtained with consent from adult patients undergoing surgical resection due to medial rectus underaction or overaction and were prepared for histologic examination by fixation and paraffin embedding. Control muscles were obtained from cornea donor eyes of adults who had no history of strabismus or neuromuscular disease. Cross sections were obtained and stained immunohistochemically for the presence of activated satellite cells, as identified by MyoD immunoreactivity, and the presence of the total satellite cell population, as identified by Pax7 immunoreactivity. The percentages of MyoD- and Pax7-positive satellite cells per 100 myofibers in cross section were calculated. RESULTS As predicted from results in the literature, MyoD-positive satellite cells, indicative of activation, were present in both the control and resected muscles. In the underacting medial rectus muscles, the percentages of MyoD- and Pax7-positive satellite cells, based on the number of myofibers, were approximately twofold higher than the percentages in the control muscles. In the overacting medial rectus muscles, the percentage of MyoD-positive satellite cells was twofold less than in the control muscles, whereas the percentage of Pax7-positive satellite cells significantly increased compared with that in the control specimens. CONCLUSIONS The presence of an increased number of activated satellite cells in the resected underacting medial rectus muscles and the decreased numbers of activated satellite cells in the overacting muscles was unexpected. The upregulation in the number of MyoD-positive satellite cells in underacting muscles suggests that there is potential for successful upregulation of size in these muscles, as the cellular machinery for muscle repair and regeneration, the satellite cells, is retained and active in patients with medial rectus underaction. The decreased number of activated satellite cells in overacting MR muscle suggests that factors as yet unknown in these overacting muscles are able to affect the number of satellite cells and/or their responsiveness compared with normal age-matched control muscles. These hypotheses are currently being tested.

Extraocular Muscles in Patients With Infantile Nystagmus: Adaptations at the Effector Level

OBJECTIVE To test the hypothesis that the extraocular muscles (EOMs) of patients with infantile nystagmus have muscular and innervational adaptations that may have a role in the involuntary oscillations of the eyes. METHODS Specimens of EOMs from 10 patients with infantile nystagmus and postmortem specimens from 10 control subjects were prepared for histologic examination. The following variables were quantified: mean myofiber cross-sectional area, myofiber central nucleation, myelinated nerve density, nerve fiber density, and neuromuscular junction density. RESULTS In contrast to control EOMs, infantile nystagmus EOMs had significantly more centrally nucleated myofibers, consistent with cycles of degeneration and regeneration. The EOMs of patients with nystagmus also had a greater degree of heterogeneity in myofiber size than did those of controls, with no difference in mean myofiber cross-sectional area. Mean myelinated nerve density, nerve fiber density, and neuromuscular junction density were also significantly decreased in infantile nystagmus EOMs. CONCLUSIONS The EOMs of patients with infantile nystagmus displayed a distinct hypoinnervated phenotype. This represents the first quantification of changes in central nucleation and myofiber size heterogeneity, as well as decreased myelinated nerve, nerve fiber, and neuromuscular junction density. These results suggest that deficits in motor innervation are a potential basis for the primary loss of motor control. CLINICAL RELEVANCE Improved understanding of the etiology of nystagmus may direct future diagnostic and treatment strategies.

Fratura isolada de parede medial da órbita associada à redução importante de movimentação ocular: relato de caso

A 25-year-old man presented with diplopia in all fields of gaze, associated with painful ductions of the right eye, after suffering a blunt trauma in the region of the right orbit. Computadorized tomography (CT) showed a right medial isolated blowout orbital fracture. Surgical correction eliminated his complaint of diplopia and improved his binocular field of vision.

Síndrome de Opitz: relato de caso

Objetive: Description of a clinical case of a child presenting Opitz syndrome, strabismus and other oculomotor disturbances. Case report: A 3-year-old child, with penoscrotal hypos-padia, bifid scrotum, micrognathy, high palate, proeminent forehead, low nasal bridge, hypertelorism, epicanthus, low-set ears, clinodactyly, bifid spine, delayed motor develop-ment and anteriorly placed anus as manifestations of the Opitz syndrome (OMIM *145410). He presented also an alternating esotropia with crossed fixation (Ciancias syndrome), associated with manifestations of a bilateral Duanes syndrome and a vertical deviation (L/R), possibly due to dissociated actions between the RSR and the palpebral muscles of the right eye. The child died after a surgery for an anorectal reconstruction. Discussion: Although presenting ocular manifestations, there are no papers referring to the Opitz syndrome in ophthalmological publications. Those which mention strabismus have no proper descriptions of the ocular motility conditions. The present case showed important oculomotor dissociations, but their causes could not be clarified, due to the premature death of the child.

Oculomotor Status, Binocular Vision, and Stereoacuity in a Series of Keratoconus Subjects

Purpose A group of keratoconus subjects (KG) and a control group (CG) were evaluated for sensory and motor status. We tried to clarify the factors (best-corrected visual acuity [BCVA]), heterophorias, fusional amplitude, anisometropia, astigmatism) that may be associated with a binocular disturbance. Methods BCVA (logMAR) was measured. Binocular vision was checked using cover tests, striate Maddox, and a 6Δ base-down prism (simultaneous perception), a prism bar (fusion and fusional convergence break point), and Titmus Fly Test (stereopsis). Results Fifty-four subjects of the KG, 27 men (median 16 years), and 29 of the CG, 15 men (median 20 years), were evaluated. In the KG, 8 (15%) subjects had strabismus. Those whose BCVA in the worse eye was logMAR ≥0.7 had a significantly higher frequency of strabismus and absence of simultaneous perception. Spherical equivalent anisometropia ≥ 1.0 diopter (D) was significantly different in both groups as was the frequency of gross stereopsis. In comparing fine and gross stereopsis in both the KG and the CG, there was a significant difference in the frontal astigmatism between eyes in the KG (P = 0.03) and CG (P = 0.01). Conclusions In our study, the KG presented a higher frequency of strabismus and impaired binocular vision. Frontal astigmatism was different between groups with gross and fine stereopsis, in both the CG and KG. Future studies are needed to elucidate or reinforce the factors associated with the loss of binocularity in keratoconus. Testing for stereopsis may be helpful to consider in the treatment guidelines for keratoconus.

Eccentric fixation patterns, clinical findings, and reading speed in patients with bilateral toxoplasmic macular retinochoroiditis

PURPOSE To study visual acuity, refractive errors, eccentric fixation, and reading performance in patients with toxoplasmic macular retinochoroiditis. METHODS Twenty-three participants with bilateral toxoplasmic macular retinochoroiditis and 4 with toxoplasmic macular retinocho-roiditis in their unique eye were evaluated. Participants reported their eye dominance, confirmed by the Portus and Miles test. Best corrected visual acuity, spherical equivalent refraction, magnification need, and reading speed were measured. Microperimetry (MAIA, Centervue - Padova, Italy) recorded the preferred retinal locus and fixation stability by means of the bivariate contour ellipse area. Fourteen eyes from 14 normally sighted subjects served as controls. RESULTS Mean ± SD best corrected visual acuity was better in the dominant eye than in the nondominant eye: 0.9 ± 0.2 (logMAR 0.5 to 1.4) vs. 1.2 ± 0.3 (logMAR 0.6 to 1.7) (p<0.0001, paired t-test). Spherical equivalent myopia of -4.00 or higher was present in 42% of the eyes. Microperimetry was performed in 42 eyes. Eccentric fixation was observed in all examined eyes. In 14 eyes (33%), the preferred retinal locus was placed (in the retina) superior temporal to the macular lesion, in 10 (24%) superior nasal, in 6 (14%) inferior temporal, and in 12 (28%) inferior nasal. There was no significant difference in the distribution of the preferred retinal locus position between dominant and nondominant eyes (p=0.85, Pearson test). There was no correlation between reading speed and the distance between the preferred retinal locus and the estimated original foveal position (r=-0.09; p=0.73), the bivariate contour ellipse area (r=-0.19; p=0.44), or best corrected visual acuity (r=0.024; p=0.92). CONCLUSIONS Myopia is more prevalent in patients with toxoplasmic macular retinochoroiditis. Reading speed is not dependent on preferred retinal locus position, stability, or visual acuity. Nevertheless, documentation of fixation provides new data on the impact of visual impairment in these patients and may be useful for rehabilitation efforts.

The power of a shared decision-making approach in the field of ophthalmology: will what is written in the medical and lay press work for my patient?

In March 1996, several new eye drops entered the market. During his fellowship, one of the authors of this editorial had just finished preparing a prescription for a patient. He listed six medications, with the precise dosage for each, and envisioned the patient safely making it through to follow-up four months later. He was very proud of having matched a clinical diagnosis to the patient’s presenting complaint, understood its mechanisms, and recommended treatment with efficacy supported by the medical literature. Before his final talk with the patient, he stopped to confirm his plan with his supervisor. The simple question from this senior doctor was never forgotten: How will this patient, whose corrected vision is counting fingers, who lives by herself and who has several other limitations and prescriptions, be able to follow your recommendations? The young doctor returned to the patient with a simpler prescription, more modest goals, and a more frequent follow-up schedule. He has been trying to not forget that lesson since then. The lesson relates nowadays to a movement in medicine called “shared decision-making,” which is defined as an approach for treatment or screening that is decided with the patient after an informed discussion with the doctor who communicates the harms and benefits of a course of action and takes the patient’s preferences into consideration. Studies call this movement “a public imperative.” Including the patient in the decision-making process aims to promote a more open, respectful, and transparent medical practice. In addition, it is hoped that it will reduce the influence of the marketing of medical procedures and treatments by advertising that is taking the place of evidence-based decisions, a recent topic of interest in both the medical and the lay press. Including the patient’s views in the medical decision is not new, although it is probably now being applied to more informed, demanding, and empowered patients. In 1992, Emanuel and Emanuel classified the doctor-patient relationship as paternalistic, informative, interpretive, and deliberative, a spectrum in which the last two types are closer to the shared decision-making approach. Several examples were given where the treatment was tailored according to the patient’s decision, cultural and economic background, professional activity, and historical context. In the field of ophthalmology, there are a number of opportunities for including patients in the shared decision-making process. Patients want to be involved, and we must be ready. This is particularly important in light of frequently asked questions: “When should I go for cataract surgery?” “Are contact lenses possible at my age?” “Is that type of anesthesia or re-operation the best option?” “Is this frequency of visits or exams really necessary or safe?” These are just a few examples of the questions we encounter in everyday practice. Indeed, this is particularly important nowadays as patients have easy access to a lot more information, which can be either good or bad. Recent reports in the literature have revealed that the shared decision-making approach improves the doctor-patient relationship and compliance, reduces medical malpractice litigation, and potentially saves money for both patients and health care providers. This last observation is based on the idea that the shared decision-making approach works well in contrast to the so-called defensive medicine model, where more diagnostic tests and treatments are ordered without discussion with the patient to provide legal protection for the doctor. On the other hand, this model has been questioned in the literature as possibly being more expensive and time-consuming, but also because it may induce patient insecurity. The latter concern is that patients may simply be left on their own to decide on a treatment or procedure. Other excuses or barriers to applying shared-decision have been noted. “I already do it.” “My patients do not understand enough or do not want to share the decision.” “I cannot use this approach in vulnerable patients.” These and other myths about shared-decision making have been addressed by Légaré and Thompson-Leduc.

Variações no posicionamento dos eixos visuais em pacientes submetidos a cirurgias de estrabismo

PURPOSE: To determine the drift variations of the postoperative alignment in patients who underwent strabismus surgery and to identify possible risk factors associated with such occurrence. PATIENTS AND METHODS: We reviewed the variations in postoperative alignment drift of 819 patients who underwent rectus muscle surgery from January, 1995 to December, 2005 at the Hospital de Clinicas da Faculdade de Medicina de Ribeirao Preto, Universidade de Sao Paulo. The patients were divided into four groups according to the type of deviation (alternating esotropia, monocular esotropia, alternating exotropia and monocular exotropia). Changes in eye positioning were quantified in each group. RESULTS: The prevalence of variations in the postoperative angle (considering variations more than 10 ∆) among the total of studied patients was 33.5% (274 patients). In those patients, a higher frequency was found in the exotropic direction (178 patients or 65.0%) than in the esotropic direction (96 patients or 35,0%), and this difference was statistically significant (chi-square test; p<0.001). CONCLUSIONS: Eye positioning instability can occur over time in patients who underwent strabismus surgery. This incident reinforces the need for the development of alternative therapies in order to provide greater stability to the oculomotor system in the follow-up of strabismus surgery.

Bilateral Brown's syndrome in a mother and her son: case report.

This case report describes clinical data from mother and son with bilateral Browns syndrome and highlights possible genetically determined predispositions.