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PubMed1997

Modifications of and special operating tricks in the classical technique of surgery against strabismus.

Even nowadays the idea of most of the operations against strabismus is based on myectomy and reposition of the rectus muscles. At the Department of Ophthalmology of the University Medical School of Debrecen we use mainly these two methods of operation. At our Department we performed 1605 operations against strabismus during the last 10 years. 1269 of our patients had convergent, 336 had divergent strabismus. The majority of the operations were performed on patients less than 6 years of age, under general anesthesia. The outcome of the operation is successful if it results in a situation, in which torque affecting the eyeball stabilizes it in the normal position. The advantage of the combined surgical procedure is that the former muscular balance remains intact, and by relatively small intervention good results can be achieved. In the rectus muscles of squint patients anatomical and histopathological changes could be found, especially if they did not receive pleoptic treatment preoperatively. Depending on the direction of the strabismus one of the muscles is thicker, while the other is thinner, due to hyper- and hypofunction. Our surgical experience of many years showed that by modifying the classical technique of the operations with some fine technical tricks it was possible to increase the success rate. In our film we presented the right way of incising and handling the subconjunctival connective tissue (Tenon capsule) thus making it possible to lay it back to its original place at the end of the operation. This way the chance of postoperative scarring is reduced. We demonstrated how to test the contractility of the muscles by using muscle-hooks, that replaces the forceps test. In case of myectomy we demonstrated the tricks of how to handle the easiest and the finest way. In case of retroposition we can achieve perfect reconstruction and wound healing by using the shown simple technique. We also take much care of suturing the conjunctiva during operations performed on infants that is important because of their undisciplined behavior.

Anesthesia, General↗

PubMed1997

[Functional recovery in strabismus].

The paper enumerates the objectives of functional recovery in strabismus and the approaches to the achievement of these objectives. The goal in the treatment of the strabismus is obtaining a binocular sight with the remake of the divergence-convergence synergism. A three stage scheme for the treatment is made: 1st stage--the treatment of the amblyopia; 2nd stage--the correction of the strabismus deviation; 3rd stage--the recovery of the binocular sight. The conclusion is that the healing of the strabismus with "restitutio ad integrum" is a distant desire.

Amblyopia↗

PubMed1997

Indications and outcomes of strabismus repair in visually mature patients.

OBJECTIVE: To identify and examine the indications, outcomes and potential risks of strabismus surgery in visually mature patients. DESIGN: Case series. SETTING: University-based referral practice in Edmonton. PATIENTS: A total of 222 patients (115 females and 107 males) aged 9 to 69 (mean 29) years who underwent strabismus surgery for various types of strabismus (as grouped by original diagnosis). All patients were followed for at least 6 weeks postoperatively. OUTCOME MEASURES: Previous surgery and deviation in prism dioptres (delta) (distance and near), sensory status (measured by the Titmus stereotest at near) and the presence of symptoms (diplopia, abnormal head posture or asthenopia), recorded preoperatively, 6 weeks postoperatively and at the last postoperative visit. RESULTS: The patients were followed for an average of 14 months postoperatively. At the last postoperative visit 187 patients (84%) were aligned to within 15 delta of orthotropia. Overall, 116 patients (52%) demonstrated some degree of stereopsis postoperatively, compared with 78 (35%) preoperatively. A total of 116 patients (52%) had symptoms preoperatively, including diplopia, abnormal head posture or asthenopia; 88 (76%) of the 116 had complete resolution of their symptoms. Six patients (4%) without diplopia preoperatively were found to have this symptom postoperatively. CONCLUSIONS: The findings suggest that most visually mature patients under-going strabismus surgery can expect functional benefits, including improvement of alignment, preservation and occasionally restoration of sensory fusion, and elimination of diplopia, abnormal head posture and asthenopia.

Adolescent↗

PubMed1993

Factors influencing response to strabismus surgery.

Based on analyses in a series of 116 patients, we found that the response to strabismus surgery (degrees of change of ocular alignment per millimeter of rectus recession) correlated significantly with the preoperative deviation for esotropic and exotropic patients. The prediction of response to strabismus surgery was not improved significantly with the inclusion of axial length, age, and/or preoperative refractive error beyond the prediction provided with use of only the preoperative deviation, even though we have previously suggested that the response to strabismus surgery should be related to axial length. We believed that larger eyes should have a smaller response for the same number of millimeters of surgery than smaller eyes. We now believe that although the response to strabismus surgery does correlate significantly and inversely with axial length, this correlation may not be clinically important given the much stronger influence of preoperative deviation.

Adolescent↗

PubMed2004

The application of statistical process control to horizontal strabismus surgery.

PURPOSE: Although originally developed to evaluate quality in manufacturing, statistical process control (SPC) techniques may be applicable to other frequently performed standardized processes. SPC analysis has rarely been used in medicine. We employed SPC charts to analyze the outcomes of one- and two-muscle horizontal strabismus surgery for esotropia and exotropia. METHODS: During a 33-month period between October 1, 1998 and July 1, 2001, we evaluated 95 patients undergoing strabismus surgery on either one or two previously unoperated eye muscles in one or both eyes. SPC charts were used to evaluate the success and validity of our surgical guidelines for horizontal recession and resection procedures. Data were divided into 2 groups, patients with esotropia and patients with exotropia, for computerized statistical analysis using QI Analyst (SPSS, Chicago, IL). RESULTS: Our results after horizontal strabismus surgery, both esotropia and exotropia repair, appear to follow the laws of statistical fluctuation or normal random variation. Our dose-response schedule produced a resultant ocular alignment or exit angle that appeared to be in statistical control, ie, variation from orthotropia that can be expected simply from normal random chance error with only a limited number of outliers. CONCLUSION: The resultant ocular alignment or exit angle after one- or two-muscle strabismus surgery may be described by standard models of statistical fluctuation. SPC may be a valuable method to analyze the variability of the results of many ophthalmologic procedures or treatments over time with the ultimate goal of producing better patient outcomes by decreasing variability.

Esotropia↗

PubMed2003

Surgical results of patients with A-pattern horizontal strabismus.

PURPOSE: To investigate the surgical results of patients having horizontal strabismus with A-pattern associated with superior oblique overaction (SOOA). METHODS: Twenty patients with horizontal strabismus (12 exotropia [XT] and 8 esotropia [ET] with no previous strabismus surgery) with SOOA-associated A-pattern were analyzed retrospectively. Motor success was defined as a horizontal deviation of 8 prism diopters (PD) or less, 6 PD or less of vertical deviation in all gazes, and no greater than 8 PD of A-pattern. Stereoacuity was measured using the Titmus test (Stereo Optical, Chicago, IL). RESULTS: Sixty percent of patients had successful results at the final examination. No significant difference was found between the XT and ET patients in preoperative and postoperative horizontal deviations in the primary position, A-pattern collapse, or success rate (P >.05). Four patients had an induced postoperative vertical deviation. Among eight patients without stereoacuity preoperatively, four showed an average of 910 seconds of arc (40 to 3000 seconds of arc) after surgery. CONCLUSION: Simultaneous surgery on the horizontal and SO muscles in patients with horizontal strabismus with SOOA-associated A-pattern can achieve a relatively high surgical success rate and restore binocular function.

Adult↗

PubMed1999

Effect of infantile strabismus on visuomotor development in the squirrel monkey (Saimiri sciureus): optokinetic nystagmus, motion VEP and spatial sweep VEP.

PURPOSE: To determine whether squirrel monkeys made artificially strabismic in infancy had ocular fixation abnormalities, directional asymmetries of horizontal optokinetic nystagmus (OKN) and asymmetries of motion visually evoked potentials (MVEPs) similar to those of humans with infantile strabismus. METHODS: Esotropia was produced in a newborn squirrel monkey by surgical tenotomy of both lateral rectus muscles. The alignment and eye rotations of the monkey were examined longitudinally and VEP testing was performed at the age of one year. Visual acuity was measured using spatial frequency sweep VEPs (SSVEP) in response to grating stimulation. OKN was tested under conditions of monocular viewing using full-visual-field, vertically oriented, moving stripes. MVEPs in response to horizontal motion were recorded with the animal sedated to reduce the possibility of eye movement artifact. RESULTS: The artificially strabismic squirrel monkey displayed a constant, committant esotropic strabismus accompanied by latent nystagmus. Monocular SSVEP acuity was subnormal in one eye, consistent with mild monocular strabismic amblyopia. The monkey demonstrated asymmetric OKN favoring nasally-directed stimulus motion when viewing with either eye. Monocular MVEPs were also characterized by a horizontal asymmetry with a directional bias inverted 180 degrees between the right and the left eyes. The eye movements and MVEP asymmetries were similar to those observed in strabismic macaque monkeys and humans with early-onset strabismus. Neither the OKN asymmetry nor the MVEP asymmetry was evident in a normal squirrel or normal macaque monkey. CONCLUSION: The artificially strabismic squirrel monkey is an appropriate eye movement and VEP model for the study of neural mechanisms in human infantile strabismus.

Animals↗

PubMedDate not supplied

Visual recognition time in strabismus: small-angle versus large-angle deviation.

PURPOSE: To measure the possible differences in monocular detection time of a threshold visual acuity stimulus (recognition time [RT]) between patients with small-angle and large-angle strabismus. METHODS: Ten patients with free alternating esotropia were tested (10 to 18 years old): five with small-angle esotropia (< or = 7 degrees), five with large-angle esotropia (15 degrees to 20 degrees). Six age-matched normal subjects served as controls. The RT of the threshold stimulus was measured in both eyes sequentially for stimuli presented in the center of a computer monitor (RT 1). Moreover, we measured the time necessary for identifying the same threshold visual acuity stimulus generated on the computer screen in the moment in which fixation is taken up by one eye after occlusion of the second eye (RT 2). Using the same setting, RT was also measured monocularly in all strabismic and normal subjects who were originally looking at a luminous fixation point positioned horizontally at 6.5 and 15 degrees from the center of the monitor (RT 3). RESULTS: The multivariate analysis of variance for repeated measures indicated that there was no statistical difference in RT 1 between groups. The mean RT 2 was significantly longer (p<0.001) in large-angle strabismic eyes when compared with that of normal control eyes. The mean RT 2 in small-angle strabismic eyes did not differ significantly from that of normal eyes. Finally, RT 3 (both at 6.5 degrees and 15 degrees of eccentricity) did not show any significant difference in the three different study groups. CONCLUSIONS: The authors hypothesized that alternating strabismus patients may have a significant advantage in maintaining a small-angle deviation, as a large-angle deviation would require longer RT in the moment the deviated eye takes up fixation. It can be speculated that the extension of re-fixation movement, obviously shorter in small-angle strabismus patients, is the main factor responsible for longer RT occurring in large-angle strabismus patients.

Adolescent↗

PubMed2003

Strabismus requires Flamingo and Prickle function to regulate tissue polarity in the Drosophila eye.

Tissue polarity in Drosophila is regulated by a number of genes that are thought to function in a complex, many of which interact genetically and/or physically, co-localize, and require other tissue polarity proteins for their localization. We report the enhancement of the strabismus tissue polarity phenotype by mutations in two other tissue polarity genes, flamingo and prickle. Flamingo is autonomously required for the establishment of ommatidial polarity. Its localization is dynamic throughout ommatidial development and is dependent on Frizzled and Notch. Flamingo and Strabismus co-localize for several rows posterior to the morphogenetic furrow and subsequently diverge. While neither of these proteins is required for the other's localization, Prickle localization is influenced by Strabismus function. Our data suggest that Strabismus, Flamingo and Prickle function together to regulate the establishment of tissue polarity in the Drosophila eye.

Animals↗

PubMed2001

Recently acquired diplopia in adults with long-standing strabismus.

BACKGROUND: The evaluation and management of recent-onset diplopia in an adult with a history of long-standing strabismus can be perplexing and challenging. No guidelines exist, to my knowledge, for the examination of such patients. DESIGN: A retrospective medical record review. SUBJECTS: Patients seen in my practice with a history of recently acquired diplopia and a history of strabismus dating back to childhood. RESULTS: One hundred fifty-two patients who met the enrollment criteria were identified. Using the treatment approach outlined herein, 132 patients were relieved of their symptoms of diplopia. In most cases, the onset of the diplopia could be correlated with a change in the patient's ocular alignment, refractive needs, or refractive management. Returning patients to their motor status before the onset of symptoms or addressing the change in refractive needs or management usually resulted in relief of symptoms. CONCLUSION: In most cases, adult patients with a history of long-standing strabismus and a recent onset of diplopia can be effectively treated.

Adolescent↗

PubMed2005

Visuo-vestibular eye movements: infantile strabismus in 3 dimensions.

Infantile strabismus is accompanied by latent nystagmus, primary inferior oblique muscle overaction, and dissociated vertical divergence. If we examine the evolutionary underpinnings of these ocular rotations, we can construct a unifying mechanism for the sensorimotor abnormalities that arise in humans with infantile strabismus. Latent nystagmus, primary inferior oblique muscle overaction, and dissociated vertical divergence correspond to visual balancing reflexes that are operative in lateral-eyed animals in yaw, pitch, and roll, respectively. In humans with infantile strabismus, these subcortical visual reflexes are reactivated by a physiologic imbalance in binocular visual input, which resets central vestibular tone in 3-dimensional space. These visual reflexes reveal the evolutionary role of the eyes as sensory balance organs that can directly modulate central vestibular tone. Latent nystagmus, primary oblique muscle overaction, and dissociated vertical divergence should be reclassified as visuo-vestibular eye movements.

Animals↗

PubMed1981

Suspected malignant hyperthermia in a strabismus patient. A case report.

Malignant hyperthermia is an autosomal dominant disorder with variable expressivity that is caused by a membrane defect in the sarcolemma of myofibrils. A patient with strabismus (esotropia) had tachycardia and masseter muscle rigidity on exposure to succinylcholine chloride and halothane, but because of rapid recognition of the condition and discontinuation of the procedure, the potentially lethal complications of malignant hyperthermia did not develop. A serum creatine phosphokinase level showed a substantial increase above normal. Two weeks later, the patient underwent successful correction of the strabismus under general anesthesia, using morphine sulfate and thiopental sodium without complication. This condition is of interest to ophthalmologists because it occurs with increasing frequency in patients with strabismus and ptosis, and it may be triggered by certain local anesthetic agents often used by ophthalmologists.

Adolescent↗

PubMed1988

Effects of convergent strabismus on spatio-temporal response properties of neurons in cat area 18.

Single-cell recording experiments were carried out to determine whether rearing kittens with surgically induced convergent strabismus (esotropia) alters the development of receptive field (RF) properties of neurons in area 18. In agreement with previous work on kittens with divergent strabismus (exotropia), there was a marked loss of binocularly driven cells in area 18 of esotropic cats. In contrast to the striate cortex of strabismic cats, the spatial properties of area 18 neurons, including receptive-field size and spatial frequency tuning, did not differ from those in normal controls. On the other hand, we found that contrast thresholds, measured at an optimal spatial frequency, were significantly elevated, and that the contrast gain in many cells was reduced in strabismic cats. These deficits were observed in both eyes, though the cells dominated by the deviating eye had a lower response amplitude at all contrasts. Furthermore, temporal frequency tuning curves were abnormal in strabismic cats in that the optimal frequencies and temporal resolutions were shifted to lower values. These effects were also bilateral. Velocity tuning, measured with a high-contrast bar stimulus, revealed that area 18 neurons in strabismic cats were unable to respond to very high velocities compared to normals. This reduced response was more severe when measured with the deviating eye in spite of the bilateral nature of the deficit. Finally, latencies to electrical stimulation of the optic chiasm or the optic radiation were significantly longer in strabismic cats. The magnitude of these effects was virtually the same for both eyes. From these observations, we conclude that the temporal properties of area 18 neurons, particularly the cells abilities to follow fast temporal modulations, are affected by raising kittens with surgically induced convergent strabismus.

Animals↗

PubMed1988

Long-term results after strabismus surgery.

The results of surgery after 4 years' or more postoperative follow-up have been evaluated in a total of 1031 cases (575 esotropia, 456 exotropia). There is a difference in the angle of strabismus 1 month after surgery and 4 years after surgery. Based on these findings, the results of strabismus surgery must be evaluated after a sufficient amount of time has passed. The angle of strabismus to be aimed at, to provide best binocular vision and patient satisfaction, should be in the range of -2 +7 degree for esotropia and +2 -10 degree for exotropia, regardless of the patient's age at surgery.

Age Factors↗

PubMed1988

Rectus muscle position in V-pattern strabismus. A study with coronal computed tomography scanning.

Coronal computerized tomographic (CT) scans were obtained on ten children with previously unoperated V-pattern strabismus and ten control patients to determine the relationship of rectus muscles to the globe. All patients with V-pattern had sufficient overaction of the inferior oblique muscles to warrant bilateral surgical weakening. Control patients had no strabismus or isolated horizontal deviations without A- or V-patterns. Using a horizontal reference line constructed along the anterior cranial fossa, the mean horizontal rectus-muscle axes were found to approximate the expected value of 180 degrees closely. The vertical rectus muscle axes were excyclotorted in both groups. However, there was no significant difference in the mean superior temporal quadrant angles formed by the intersection of the horizontal and vertical rectus muscle axes. Analysis of covariance with age as the covariant demonstrated a significant relationship (P less than 0.01) between age and the superior temporal quadrant angle measured in each eye. Our data suggest that apparent rectus muscle malposition identified by CT scanning is a function of age and cannot be implicated as an important cause of V-pattern strabismus.

Age Factors↗

PubMed1996

Recurrent intrascleral cyst after strabismus surgery.

BACKGROUND: Intrascleral epithelial inclusion cysts have been described after ocular trauma, scleral buckling and strabismus surgery. They are usually small, asymptomatic and located anteriorly. CASE REPORT: The clinical history of a 9-year-old girl who developed a huge epi- and retrobulbar intrascleral cyst in both the upper and the lower nasal quadrants after multiple strabismus operations is described. RESULTS: Surgical resection of the cyst wall was twice unsuccessful. Drainage of the cyst, followed by the injection of tetracycline (30 mg/ml) in the cyst site, led to complete recovery. CONCLUSION: Recurrent posteriorly located intrascleral cyst can occur after strabismus surgery. Therapy consisting of drainage combined with intrascleral administration of tetracycline solution (30 mg/ml) to induce sclerodesis appeared to be effective during a 2-year follow-up period.

Anti-Bacterial Agents↗

PubMed1991

Serum gastrin and blood glucose levels during halothane-nitrous oxide anaesthesia and strabismus surgery in children.

The purpose of this study was to determine whether serum gastrin levels are increased by reflexogenic stimuli applied to the extrinsic muscles of the eye. Serum gastrin and blood glucose concentrations were measured in ten normal children aged between 5 and 12 yr during general anaesthesia with halothane and nitrous oxide and during strabismus surgery. Fasting basal concentrations of gastrin (33.6 +/- 14.8 pg.ml-1) and of glucose (4.43 +/- 0.72 mmol.L-1) were in the normal range of values for children. Intravenous atropine (0.01 mg.kg-1), general anaesthesia with halothane in nitrous oxide and oxygen by mask for three minutes, tracheal intubation, extraocular muscle stimulation and surgical stress did not cause any variation in the mean serum gastrin concentration. On the contrary, tracheal intubation and surgical stress increased blood glucose concentrations (P less than 0.05). There was no difference in the serum gastrin levels after extraocular muscle stimulation between children with positive or negative oculocardiac reflexes (44.5 +/- 16.7 pg.ml-1 vs 38 +/- 14.7 pg.ml-1, respectively). The incidence of vomiting predischarge was 60 per cent. Serum gastrin levels did not differ between children who vomited and children who did not (44.3 +/- 18.5 pg.ml-1 vs 47.1 +/- 16.9 pg.ml-1, respectively). Vomiting after strabismus surgery cannot be attributed to high gastrin serum levels. Consequently, it is unlikely that vomiting after strabismus surgery is linked to an "oculogastric reflex" with the vagus nerve as the efferent pathway.

Anesthesia, Inhalation↗

PubMed1997

Low incidence of the oculocardiac reflex and postoperative nausea and vomiting in adults undergoing strabismus surgery.

PURPOSE: To investigate the incidence of the oculocardiac reflex (OCR), and of postoperative nausea and vomiting (PONV) in adults undergoing strabismus surgery. METHODS: Adults (18-86 yr) undergoing inpatient strabismus surgery received 10 micrograms.kg-1 atropine and 10 micrograms.kg-1 altentanil iv and were randomly allocated to: (A) 5 mg.kg-1 thiopentone iv, isoflurane/N2O maintenance; (B) 3 mg.kg-1 propofol iv, propofol/N2O maintenance (10-14 mg.kg-1.hr-1); 3 mg.kg-1 propofol iv, propofol/air/O2 maintenance (10-14 mg.kg-1.hr-1). Analyses were with the number-needed-to-treat/harm. RESULTS: In 97 adults the absolute risk of OCR (13-20%) and PONV (21-31% after 24 hr) was low, with no differences between groups. Number-needed-to-treat to prevent PONV with propofol with or without N2O compared with thiopentone-isoflurane was 7 to 11. Number-needed-to-harm for one OCR with propofol compared with thiopentone-isoflurane was 17. CONCLUSION: Adults undergoing strabismus surgery with prophylactic atropine had a low risk of OCR and PONV, independent of the anaesthetic technique used.

Adolescent↗