Harley E. A. Bicas

Células satélites musculares

The article describes myogenic satellite cells, their markers, quantification and distribution, growth factors and hormones involved in their regulation, interaction with macrophages and monocytes, functional answers to physiologic stimuli/disease states, genetic models of myopathies and muscular regeneration, ectopic muscle formation, muscle formation and precursor cell, satellite cell origin, peripheral cells, extraocular muscles and satellite cells.

Acuidade visual: medidas e notaçöes

Evaluations of the visual function are very intricate since they depend on afferent, efferent and cognitive mechanisms, besides external factors of the examined subject, such as the type of the stimulus and of its presentation. Testing the visual acuity is discussed in its formal aspects related to definitions, quantifications (criteria for the measurements of an angle, size of optotypes), notations (decimal or fractionary), scales (representing angular, linear or logarithmic relationships) and units in which the values are expressed (reciprocal of minutes of arc, pure number, spacial frequency, decibels, octaves). As a consequence, numerical references about visual acuity and respective operations (e.g., calculations of average values, determinations of variations, relationships between them) may lead to very different interpretations of a study, sometimes even opposite, according to the criteria which are used.

Comparison of corneal changes after phacoemulsification using BSS Plus versus Lactated Ringer's irrigating solution: a prospective randomised trial

Background/aims To compare two intraocular irrigating solutions, Balanced Salt Solution Plus (BSS Plus) versus Lactated Ringers (Ringer), for the preservation of corneal integrity after phacoemulsification. Methods 110 patients undergoing phacoemulsification were randomised to either BSS Plus (n=55) or Ringer (n=55) as the irrigating solution. Patients were examined at baseline and at 1, 8, 15, 30 and 60 days postoperatively. Evaluations included specular microscopy to evaluate endothelial cell density (ECD) and endothelial cell size variability (CV), and corneal pachymetry for central corneal thickness (CCT) measurement. Results Groups were well balanced regarding baseline ECD, CV and CCT (p>0.05). There was no statistically significant difference between ECD reduction in group BSS Plus 13.1±2.0% and Ringer 9.2±1.9% (p<0.05) at day 60 or in any study visit. There was no statistically significant difference between CV increase in group BSS Plus 23.0±3.0% and Ringer 20.2±4.0% (p<0.05) at day 60 or in any study visit. CCT was significantly increased (p<0.05) at 1, 8, 15 and 30 days postoperatively, returning to baseline at 60 days in both groups. There was no significant difference in CCT increase in both groups at any visit. Interestingly, there were statistically significant correlations between ECD loss and phacoemulsification time (p<0.0001) and ECD loss and irrigation solution volume (p<0.0001) in the Ringer group, but not in the BSS Plus group. Conclusions Ringers solution was similar to BSS Plus for corneal preservation in atraumatic cataract surgery. However, our study demonstrates that there is a trend towards lower postoperative endothelial cell density for surgeries with longer phacoemulsification time and higher irrigation volumes if Ringer is used. Trial registration number NCT00801358.

Fisiologia da visão binocular

The binocular vision of human beings is given by the almost complete superimposition of the monocular visual fields, which allows a finer perceptual discrimination of the egocentric localization of objects in space (stereopsis) but only within a very narrow band (the horopter). Before and beyond it, diplopia and confusion are present, so that a physiologic (cortical) suppression is necessary to avoid them to become conscious. The geometry of the horopter and its physiologic implications (Hillebrands deviation, Kundts partition, Panums area, stereoscopic vision) are analyzed, as well as some clinical aspects of the normal binocular vision (simultaneous perception, fusion, stereoscopic vision) and of adaptations to abnormal states (pathologic suppression, amblyopia, abnormal retinal correspondence).

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.

Toxina botulínica no tratamento de estrabismo horizontal em crianças com paralisia cerebral

To evaluate the efficacy of botulinum toxin injection in the treatment of horizontal strabismus in children with cerebral palsy. METHODS: A group of 24 patients, age 6 - 156 months, with cerebral palsy and horizontal strabismus (17 esotropias ranging from 25 to 45 PD and 7 exotropias ranging from 20 to 45 PD) were treated with botulinum toxin (34 medial rectus and 14 lateral rectus muscles). The children underwent full ophthalmic examination. The injection treatment was performed after sedation using Mendoncas forceps. The follow-up was done after 7 days, 15 days and monthly. Deviation less or equal of 10 PD after 6 months of follow-up was considered successful. However, if patients did not achieve this result a second application could be performed. RESULTS: In the group of esotropia (n=17) 47.1% had successful results with only one application after two years of follow-up. All of these patients had previous deviation less than or equal to 35 PD. In the exotropia group a single injection was not sufficient to achieve successful result. The side effects included: subconjutival hemorrhage in 4 (16.7%) patients, transient vertical deviation in 4 (16.7%) and transient ptosis in 22 (91.7%). CONCLUSION: The use of botulinum toxin was a good alternative in the treatment of children with cerebral palsy and esotropia.

Cirurgias de músculos retos horizontais: análise de planejamentos e resultados

Purpose: Retrospective study of surgical results of the correction of horizontal strabismus in a University Hospital. Methods: In selected cases of comitant eso- and exotropias, without signs of oculomotor paralyses or restricted ocular rotations, surgeries of: recessions of both medial recti (group A), or both lateral recti (group C) were performed, recession-resection for esotropias (group B) or for exotropias (group D), with or without transpositions of the respective muscular insertions. Results: The number of esotropias was greater than that of exotropias (nA = 66; nB = 28; nC = 27; nD = 22) as well as surgeries in which transpositions were done (96) surpassed surgeries without transpositions (47). The distributions of the preoperative angles (m = 42.49D, s= 11.68D for esotropias; m= 35.38D, s= 9.93D for exotropias) and of the respective obtained corrections (m = 38.95D, s = 13.57D for esotropias; m = 31.64D, s = 14.58D for exotropias) were practically equivalent. In addition, high correlations were observed between the pre-op angles and the amount of the respective operations. However, the correlations between the pre-op angles and the proportional results of the surgeries (given in D/mm) were always low. The amount of corrections when residual angles of ±5D, ±10D and ±15D were considered reached respectively 31.9%, 62.8% and 80.8% for esotropias, and 40.8%, 55.1% and 73.5% for exotropias. Conclusions: Although the surgical plans and the respective operations give satisfactory results in a general analysis, the individual outcomes are highly unpredictable.

Oculomotricidade e seus fundamentos

The paper starts from a schematic circuit establishing a relationship of the sensorial (visual, binocular) with the oculomotor systems, whose defects of their afferent or efferent pathways, or of their interactions, explain the emergence of strabismus with its consequences. The foundations and referentials of ocular movements are then examined: the concepts of axes and planes, of the centers of mass and of rotation, of monocular displacements of translation and rotation, of binocular version and vergence displacements. The functions of centers of command for voluntary or reflex ocular movements are also presented, as well as the innervation of extrinsic ocular muscles. In a second part (physiology of the extrinsic ocular muscles), activities of contraction or relaxation and the importance of Sherringtons law are commented. The concepts of primary position of gaze and of the referentials for rotations are retaken leading to the diversity of the several systems of measurements. There follows analysis of the rotational actions of the ocular muscles, based on the so-called planes of muscular actions and on the anatomic distribution of the muscles, leading to the results in primary position of gaze and others. The effects of fascias and intermuscular membranes are also commented. Conclusively the modern concept of the muscular actions is presented (simultaneous actions of all muscles in each ocular position). Based on the conditions of Herings law the concept of positions for the diagnosis of the oculomotor disfunctions, which differs from the classical one is developed: the muscles are considered in pairs, according to their predominant actions ___ horizontal (horizontal recti), vertical (vertical recti) ou torsional (oblique muscles). For each corresponding pair, the actions in diametrally opposite conditions of ocular fixation and gaze position are compared. For example, supradextroversion, with fixation of the right eye and infralevoversion with fixation of the left eye in order to compare the actions of the right superior rectus and of the left inferior rectus, respectively. The influence of the head tilt upon such actions is also analyzed. The paper also studies the synkinetic relationship between accommodation and convergence, proximal convergence, and the units of those functions.

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.

A major problem in strabismus and its possible solution

PURPOSE One of the challenges in strabismus is to guarantee stability of the surgical corrections. Re-surgeries are often required even after careful diagnosis, planning, and execution. Several factors contribute to this undesired outcome and the existing management strategies are ineffective. The present alternative is to compensate for their consequences. Ocular rotations are evoked by muscular contractions and relaxations (active forces). During eye movement, periocular tissues are stretched, storing part of the kinetic energy, which may be posteriorly recovered (passive forces), whereas the remaining part of the energy is lost via friction and inelastic deformations (dissipative forces). A method for measuring the forces that cause post-surgery eye drift has not been reported. However, this may be indirectly determined as a function of the respective mechanical variables. The estimated ratio between the kinetic energies of a post-surgery eye drift and a normal pursuit eye movement is ~10(-15). Theoretically, it can be expected that the addition of continuously acting forces of such magnitudes to the oculomotor system might prevent the undesired post-surgery eye movement. METHODS Several methods for increasing the restraining, dissipative forces to ocular rotations may be conceived. One method is to increase the friction to ocular movements, as for instance, by periocular injection of viscous substances. Another possibility is to use the forces of a magnetic field, which may stabilize the eye in a desired position without avoiding the rotations caused by greater muscular forces acting on it. It has been demonstrated that these forces neutralize the nystagmic movements, whose intensities of mechanical variables are much higher than those of a post-surgery eye drift. Some models of application of this technique are then discussed. Small magnets fixed to the orbit and metallic ferromagnetic elements fixed to the sclera to cover a suitable extension appears to be the best method for providing starting and sliding friction to the oculomotor system. RESULTS Weak magnetic fields do not cause ocular ill effects. Additionally, the magnetic field may be confined to the elements of the circuit and may not leak. However, the magnetic materials may interfere with magnetic resonance image (MRI) examinations.