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PubMed1988

Measurements of active and passive force of horizontal muscles in strabismus.

A precision device was developed for quantitative measurement of the active and passive forces of the horizontal muscles in several different types of strabismus. The device consists of a tension gauge for measuring isometric muscle tension (active force) and passive length-tension (passive force), and a circular-motion guide mechanism. In normal subjects, the active force showed nearly linear changes with the eye position, as was reported in past studies. A similar relationship between the active force and the eye position was observed also in strabismus patients in our study. Normal subjects showed a stronger force in the medial than the lateral rectus muscle. Among strabismus patients, those with normal retinal correspondence (NRC)-intermittent exotropia showed a force closest to that of the normal controls. However, the force of the lateral rectus muscle was significantly greater in those with constant exotropia than in the normal controls. The active force of the medial rectus muscle was significantly smaller in those with dual retinal correspondence (DRC)-intermittent exotropia and constant exotropia. Conversely, the active force of the medial rectus muscle was significantly greater in those with esotropia, compared with the normal group. As for the passive force, there was no significant difference between the temporal passive force and the nasal passive force in the normal and esotropic groups, but the temporal passive force was significantly greater in the esotropic group. The magnitude of the force was greater in both directions when traction was applied against the muscle having the stronger active force. These results suggest that the lateral rectus muscle force is relatively stronger in patients with DRC-intermittent exotropia due to a weakness of the medial rectus muscle force, and that the absolute strength of the lateral rectus muscle force is increased in patients with constant exotropia, but in NRC-intermittent exotropia the muscle forces are almost normal. Those with esotropia are considered to have an absolute increase in the medial rectus muscle force.

Adolescent↗

PubMed1987

[Critical study of sectorial occlusion in the treatment of strabismus in children].

Sector occlusion, already described in 1953, has been used regularly since Berrondo's first publication on the subject in 1967 by a great number of ophthalmologists and orthoptists for convergent concomitant and sometimes divergent strabismus treatment. Sectors limit the field of fixation of each eye, in order to modify the optomotor reflex to restore and maintain the sensory and motor alternation. The mostly used sector designs are the symmetrical or asymmetrical binasal ones. The way of action of middle, narrow or broad, straight or oblique, or eventually "V" shaped binasal sectors can easily be analysed; their application does'nt present any particular difficulties; their reproduction is easy. Such is not the case of the so called "buridanization", location/observation and other numerous sophisticated shapes suggested by Berrondo. Sector-occlusion indications, advantages and disadvantages, limits and counter-indications are related in details. There is no doubt that binasal sectors represent a major acquisition for concomitant strabismus visual reeducation; they are irreplaceable in the treatment of congenital strabismus.

Amblyopia↗

PubMed1985

Congenital, latent and manifest latent nystagmus--similarities, differences and relation to strabismus.

Patients with congenital types of nystagmus, including congenital nystagmus (CN), latent/manifest latent nystagmus (LMLN) and combinations of the two, can be identified by waveform analysis and classified into three unambiguous groups. This categorization by waveform is supported by different clinical signs, including the relationship to strabismus. Strabismus is essential for LMLN but incidental to CN; most CN patients do not have strabismus. Seventy-seven percent of CN patients have a convergence null, 57% a gaze angle null and nearly half have both; only 14% have neither. Also supporting this patient grouping by waveform is the high incidence of patients in each of the two major groups (ie, they had either only CN waveforms or only the LMLN waveform). Comparing the incidence of each CN waveform, or combinations of waveforms, in families with that in the general CN population, reveals that heredity plays a role in determining waveform; heredity also affects other characteristics, such as gaze angle or convergence nulls. The nystagmus blockage syndrome has at least two mechanisms and the patients, therefore, can belong to either of two groups. Spasmus nutans is hypothesized to be an oscillation of the vergence system and therefore, unrelated to CN or LMLN.

Child, Preschool↗

PubMed1983

Strabismus after retinal detachment surgery.

In conclusion, we can summarize our experience as follows: Exoplants oriented radially and wherever placed can be productive of important degrees of astigmatism and diplopia. In our experience, they are often associated with torsional diplopia; Surgery under the rectus muscles may be responsible for adhesions and limitations of excursion of the globe; Anteriorly placed exoplants, especially those placed under the rectus muscles and particularly temporally or below, are apt to erode the overlying muscle sheath and tendon; a muscle so eroded may sometimes be found reattached to the globe just posterior to the exoplant; Repeated surgical intervention, perhaps in association with careless or inaccurate closure of the periocular tissues, Tenon's fascia and conjunctiva, may be important factors in the production of strabismus; Factors which have not been responsible for strabismus as far as we can tell are encircling elements without exoplants and intraoperative detachment and reattachment of the extraocular muscles. I know of no instance where these alone have been productive of an important postoperative strabismus.

Adult↗

PubMed1983

Saccadic velocity measurements in strabismus.

Traditional evaluation of strabismus has included cover test measurements, evaluation of the range of ocular rotations, and an array of subjective sensory tests. These studies could not always differentiate paresis of an extraocular muscle from restrictions and from various neuro-ophthalmic motility disorders. The measurement of horizontal and vertical saccadic movements can provide an objective test of rectus muscle function. Using EOG, saccades can be recorded easily, inexpensively, and repeatably at any age. In ocular muscle paresis or paralysis, saccadic speed is reduced mildly to markedly and can be used to monitor recovery. Assessment of saccadic velocity does not appear useful in evaluating superior oblique palsy, although it is valuable in sixth nerve palsy, Duane's syndrome, and third nerve palsy. When restrictions are the major cause of limited rotation, as in thyroid ophthalmopathy and orbital floor fracture, saccadic speed is unaffected. The induction of OKN or vestibular nystagmus is helpful in the study of children too young to perform voluntary saccadic movements. In patients with limitation of elevation or depression, this technique can separate innervational from mechanical causes of diminished rotation. The specific saccadic velocity pattern in myasthenia gravis, progressive external ophthalmoplegia, internuclear ophthalmoplegia, and Möbius' syndrome is helpful in differentiating these disorders from other neuroophthalmic motility problems. Transposition surgery of the rectus muscle is effective because of an increase in force, seen as an improvement in saccadic velocity and resulting from the change of insertion of the muscles. Saccadic velocities can also be of assistance in diagnosing a lost or disinserted muscle following surgery for strabismus. Although analysis of saccadic velocity is not required for the proper evaluation of all problems in strabismus and motility, it can be of inestimable value in the diagnosis of many complex and confusing disorders. Together with forced duction testing, a clinical profile can be obtained concerning muscle force and muscle and orbital restrictions, which are required information for appropriate surgical planning.

Abducens Nerve↗

PubMed1981

Botulinum toxin injection of eye muscles to correct strabismus.

One hundred thirty-two doses of botulinum A toxin were injected into 42 humans. The effect on horizontal strabismus was uniformly beneficial, and effect lasting up to 411 days since the last injection was documented. The effect in vertical strabismus and lid retraction was beneficial, but less strongly so. No systemic effect or local complications were encountered except for effect on adjacent muscles. The drug appears to be a safe and useful therapy for strabismus.

Absorption↗

PubMed1982

[Physiological or sensorial approach to the early treatment of strabismus (author's transl)].

Results obtained in 142 cases out of a total of 1.460 patients with non-accommodative strabismus treated and follow-up for 15 years are analyzed. Basic treatment was sensorial, started at a very early stage, supplemented by surgical correction of the mechanical defect. Complete recovery was obtained in 76 p.cent of cases, good vision with a very small angle (2-4 dpt.) microtropia in 17 p.cent, and a residual angle of 8-15 dpt. ni 7 p.cent. Similar results were obtained in small angle and congenital strabismus cases: following orthoptic therapy alone in 25.7 p. cent of patients, and after a single operation in 69.2 p.cent. No case of secondary divergence occurred and results remained stable during the 15 year period due to the fusion lock. It is the only treatment of surgical undercorrections and of the rare recurrences, and probably a causal treatment of spasms. Results suggest that sensorial physiological treatment should be basic treatment; A.R.C. should become as obsolete as excentric fixation amblyopia; this treatment emphasizes the crucial role of the orthoptist who really cures the strabismus. It is the "historical transition" of Jampolsky.

Adolescent↗

PubMedDate not supplied

[Results of strabismus surgery in adolescents and adults: cosmetic or functional recovery?].

PURPOSE: To answer the question, whether it is possible to achieve a functional improvement after strabismus surgery in adults. METHODS: The study comprised 71 patients, aged 13-53, in whom after strabismus surgery, deviation was reduced to +/- 4 degrees. The degree of binocular vision was examined with weak and strong dissociating tests. RESULTS: Complete binocular vision was achieved in 25% of cases, partial with peripheral fusion in 51%. The degree of binocular vision depended on the following factors: type of squint and time of its development, degree of amblyopia, refraction and presence of binocular vision before the surgery. In some cases binocular vision occurred immediately after surgery, in others in a long follow-up. Stabilization of surgical effect was observed in the cases with peripheral fusion. CONCLUSION: Strabismus surgery in adults could be a chance for functional recovery and not only for aesthetic improvement.

Adolescent↗

PubMed1995

[Cyclic strabismus. Presentation of two new cases and critical review of the literature].

Description of cyclic strabismus has been restricted for a long time to circadian esotropia. In this mysterious phenomenon, the eyes are crossed every other day with no binocular vision, but remain perfectly normal during the straight days. The usual characteristics are those of a non-accommodative and non-paretic strabismus, with onset in early childhood. There is no response to conservative treatment, and the cycles become irregular with time until the deviation becomes constant, with an excellent functional result after surgery in every case. Recently, other papers comprising data irrelevant to the classic picture suggest that cyclic strabismus includes, in fact, several different entities. The only common point is the existence of ocular motility disorders that recur more or less regularly, and whose pathologic substrate is primarily heterogeneous, whether it is thought as a mere hypothesis or a likely mechanism. Two new cases of circadian esotropia are presented together with a review of the literature relating to the criteria of the syndrome.

Biological Clocks↗

PubMed1994

Natural strabismus in monkeys: accommodative errors assessed by photorefraction and their relationship to convergence errors.

PURPOSE: To examine accommodation and accommodative convergence relationships in naturally strabismic monkeys. METHODS: Photorefraction was used to measure accommodative responses of each eye under monocular and binocular viewing conditions. These accommodative results were then compared to assessments of vergence state made under monocular viewing conditions using methods previously described. RESULTS: Accommodation was always accurate under monocular viewing conditions, with the exception of the inability of one myopic eye to focus distant targets. The accommodative response in the two eyes was always consensual. In animals with an anisometropia, the fixating eye was focused accurately on the target, and the fellow eye was in error by an amount predicted by the magnitude of the anisometropia. Some animals alternated fixation, and, under these conditions, control of accommodation and fixation switched in tandem. Accommodative convergence ratios (AC:A) were abnormally low in animals with strabismus syndromes, similar to human essential infantile esotropia, and were excessively high in animals with syndromes, similar to human early onset accommodative esotropia. CONCLUSIONS: There was no evidence that the strabismus seen in any of the monkeys was related to errors in accommodation. However, the crosslink gain between accommodation and vergence was abnormal in some of the animals. These abnormalities have the effect of driving vergence toward a misalignment that can only be overcome by other factors, such as fusional vergence. Thus, the authors speculate that these abnormalities in synkinesis between accommodation and convergence were present during early postnatal development when fusional vergence is weak, and that they acted as predisposing factors for the development of strabismus.

Accommodation, Ocular↗

PubMed1993

Treatment of thyroid ocular myopathy with adjustable and nonadjustable suture strabismus surgery.

Our results pooled with those of others demonstrate a statistically significant improvement in outcome when adjustable sutures are implemented in the treatment of thyroid ocular myopathy. To our knowledge, this degree of significance has not been reported previously. We believe the value of adjustable suture strabismus surgery lies mainly in the prevention of large undercorrections and overcorrections. However, one cannot guarantee fusion or long-term alignment stability, especially without prism use. A randomized, prospective, controlled study to compare the nonadjustable and adjustable techniques for the treatment of thyroid ocular myopathy has yet to be performed. The success of any type of strabismus surgery relies on many factors. Future endeavors should implement the quantified adjustable suture technique to better define how preoperative conditions influence the response to strabismus surgery in Graves' patients.

Adult↗

PubMed1993

[Emesis and the oculocardiac reflex. Drug prophylaxis with droperidol and atropine in children undergoing strabismus surgery].

Although droperidol is often used to prevent emesis, vomiting is still common in children undergoing strabismus surgery. METHODS. One hundred children aged 3 to 12 years admitted for strabismus surgery were enrolled in a randomised, double-blind study to investigate the influence of the timing of the administration of droperidol (75 micrograms/kg i.v.) and the effect of atropine (10 micrograms/kg i.v.) on postoperative vomiting and the occurrence of the oculocardiac reflex (OCR). Each child was prospectively assigned to one of the following groups: Group A: atropine and droperidol before the beginning of surgery (n = 25); Group B: atropine before the beginning, droperidol after completion of surgery (n = 25); Group C: no atropine, droperidol before the beginning of surgery (n = 25); Group D: no atropine, droperidol after completion of surgery (n = 25). After oral premedication with 0.4 mg/kg midazolam, anaesthesia was induced via a face mask by inhalation of halothane, nitrous oxide, and oxygen and 1 mg/kg succinylcholine was given to facilitate tracheal intubation. Gastric contents were aspirated by a gastric tube at the end of the operation. Vomiting and retching were recorded for 24 h; recovery from anaesthesia was assessed by a modified Steward score. RESULTS. The four groups were comparable regarding age, sex, body weight, duration of anaesthesia, and number of repaired eye muscles. Patients receiving droperidol before and after the end of surgery had a similar incidence of vomiting (groups A and C 60% vs. groups B and D 50%). There was no significant difference in the number of patients vomiting between groups A and B (58%) and groups C and D (52%). The incidence of the OCR was lower in the patients premedicated with atropine (18% vs. 60%, P < 0.01). There was no statistical relationship between the occurrence of the OCR and post-operative emesis. Younger children (3 to 6 years) vomited more often than older ones (7 to 12 years). The incidence of the OCR was higher in patients with more than two eye muscles repaired than in others. Recovery scores were slightly lower in patients with droperidol after completion of surgery; postoperative recovery times did not differ significantly between the study groups. CONCLUSIONS. The timing of the administration of droperidol (75 micrograms/kg) had no influence on postoperative vomiting. The application of atropine (10 micrograms/kg) prior to surgery did not influence vomiting after strabismus surgery. Atropine (10 micrograms/kg) reduced the incidence of the OCR significantly. There was no statistical relationship between the occurrence of the OCR and postoperative vomiting.

Atropine↗

PubMedDate not supplied

A comparison of the success rates of resident and attending strabismus surgery: discussion.

Residency training involves surgery by resident surgeons at various levels of experience and proficiency, supervised by an experienced attending physician. We reviewed the results of strabismus surgery performed at four institutions with two residency training programs. Five hundred twenty-two cases with follow up greater than 6 weeks were evaluated. These cases included 315 attending procedures and 207 resident procedures under direct attending supervision. Success was defined as a strabismic deviation of 8 prism diopters or less. Average postoperative follow up was 57 weeks and did not differ between groups. There was no statistical difference between the resident success rate of 58% (121/207) and the attending success rate of 69% (217/315) after adjusting for population differences. The average final deviation of the patients postoperatively was 7 delta for the attending group and 10 delta for the resident group. Amblyopia was significantly more frequent in the resident cases (P < .001). Adjustable sutures were used significantly more often in attending cases (P < .0001). This study supports the premise that resident strabismus surgery is as successful as attending surgery. (Abstract reproduced from Wisnicki HJ, Repka MX, Raab E, et al. A comparison of the success rates of resident and attending strabismus surgery.

Follow-Up Studies↗

PubMed1977

[A comparative study of the difference in the evolution of refraction in the two eyes in patients with convergent strabismus (author's transl)].

In 329 cases of concomitant convergent strabismus, the alterations of refraction in the two eyes were compared over periods ranging from 10 to 30 years. In the group with unilateral strabismus (245 cases), a significant difference between the two eyes was observed. The change of refraction, if any, in the non-fixing eye (emmetropization or myopization) clearly lagged behind that in the fixing eye. This difference was particularly pronounced in the cases showing myopization. In the group with equivalent function of both eyes--alternating strabismus and cases with complete normalization, including functional normalization--a total of 84 cases, any emmetropization or myopization was found to run practically parallel in the two eyes. This shows that it is true of refraction, also that the genetically determined evolutive pattern may be modified by a functional abnormality.

Aging↗

PubMed1996

[Binocular vision after strabismus surgery in adulthood].

The authors tested preoperatively and postoperatively for binocularity in a series of 29 adults who underwent surgery for long-standing concomitant strabismus. The authors used Bagolini lenses, troposcope and Worth's lights as the tests for binocularity. The patients in whom the postoperative deviation was greater than 10 prism diopters from orthotropia were excluded. Binocularity was not find at any patient before surgery. The authors made a finding of binocularity after strabismus surgery in 14% of patients, in spite of satisfactory parallel ocular alignment in 52% of patients. The results of development of binocularity after strabismus surgery in adults were not as good in this series as the other authors found.

Adolescent↗

PubMed1996

[Treatment of infantile strabismus with eye movement disorders].

PURPOSE: Possibilities of application of localization method in the treatment of infantile strabismus in a very early period are presented. MATERIAL AND METHODS: The authors applied treatment with hypercorrective and compensating prisms in 17 children with infantile strabismus. The age of the children ranged from 0.5 to 5 years, mean age-1 year. All children were found to have no motility or limited motility of eyes toward the temples. Initially, the children's eyes were alternately occluded in prisms whose strength prevalently was 30-40 pr dptr before each eye, with base toward the temple. After 1-3 months motility of the eyes appeared. Next, glasses compensating the squint angle were worn, without covering the eyes, starting with 1/2 hour 3 times a day and gradually prolonging the wearing time. Hypercorrective prisms were further used with alternate occlusion of the eyes. RESULTS: In all children partial or complete correction of motility was achieved. Further treatment of strabismus followed the rules of the localization method.

Child, Preschool↗

PubMed1997

Postoperative drifts after adjustable-suture strabismus surgery.

OBJECTIVE: To determine the drift patterns and success rates of adjustable-suture horizontal strabismus surgery when patients are aligned to predetermined target angles. DESIGN: Case series. SETTING: University-affiliated tertiary care hospital in Toronto; clinic and office care. PATIENTS: A total of 109 patients aged 15 to 72 years who underwent adjustablesuture strabismus surgery (primary procedure or reoperation) for esotropia or exotropia performed by one surgeon between 1990 and 1994 who were followed for at least 6 months. Their final postoperative angles were in the target ranges of under 4 prism dioptres (PD) for esotropia surgery and 3 PD to 7 PD of esotropia for exotropia surgery. OUTCOME MEASURES: Primary-position alignment before surgery, immediately after surgery or after adjustment of sutures, if needed (final alignment), and at 1 to 2 weeks, 6 to 8 weeks and 6 to 8 months after surgery; size and direction of drift from final alignment after surgery at 6 to 8 months; and rate at 6 to 8 months of reduction of strabismus angle to less than 10 PD. RESULTS: Of the 109 patients 44 had esotropia (17 primary repair [group 1] and 27 reoperation [group 2]) and 65 had exotropia (29 primary repair [group 3] and 36 reoperation [group 4]). Overall, 48 patients (44.0%) required postoperative suture adjustment. The mean drifts from the final postoperative alignments were 1 PD for groups 1 and 2, 7 PD for group 3 and 3 PD for group 4, all in the exotropic direction. The corresponding surgical success rates were 82.4%, 92.6%, 93.1% and 94.4%. Over 6 to 8 months both esotropia groups had approximately equal tendencies to drift in either direction. Both exotropia groups showed almost equal tendencies to drift in either direction away from the mean exotropic shift for the group. CONCLUSIONS: Because of our target alignments, our success rates at 6 to 8 months were high, for both primary surgery and reoperation. In all four patient groups the drift tendencies were symmetric about the mean.

Adolescent↗

PubMed1997

[The recovery of visual performance in strabismus with eccentric fixation].

The purpose of this work is to realise a general view about the diagnosis, therapeutic methods and the results obtained in eccentric fixation strabismus. We realised a six years retrospective study on 144 eccentric strabismus, watching dynamic the evolution by testing: the orthophoric status, visual acuity, binocular vision and the type of fixation. Medium follow un time was of 19.6 months. In the end of the treatment we notice: visual acuity between 0.1-0.5 in 14% cases; central fixation in 52 children (36%); first degree of binocular vision in 15 children (10.4%) and second degree in 5 cases (3.47%). This study showed that the early installation of eccentric fixation strabismus was in 53% cases before reaching one year old and in 90% before two years old. The functional results was negative influenced by the delay in presentation (42% come after 2 years) and the difficulties in family cooperation (46.5% were followed up lesenban 6 months).

Adolescent↗