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PubMed2000

[The characteristics and curative effects of strabismus following retinal detachment surgery].

OBJECTIVE: To describe the clinical characteristics and evaluate the surgical results in strabismus eyes which all had undergone retinal detachment surgery. METHODS: This study covered 24 strabismus cases (28 eyes) following retinal detachment operations. For these, examinations involving prism with alternative cover test or Krimsky test, eyeball movement, and diplopia analysis were performed. Strabotomy was carried out combined with or without scleral buckling removal or secondary intraocular lens implantation. The post-operative follow-up period ranged from 1 month to 24 months. RESULTS: (1) The main clinical feature in 16 strabismus cases (19 eyes) having managed by rhegmatogenous retinal detachment surgery was that the character of strabismus was related to the location of scleral explants. (2) Diplopia completely disappeared in 40.9% and partly disappeared in 54.5% of the cases. Strabismus was completely corrected in 63.6% of 27 eyes and partly corrected in 31.8% of them. CONCLUSIONS: (1) The strabismus following retinal detachment surgery is a restrictive strabismus, the clinical characteristics of which are different from that of palsy strabismus. (2) Strabotomy is effective in the treatment of restrictive strabismus.

Adolescent↗

PubMed2002

Effects of the duration of early strabismus on the binocular responses of neurons in the monkey visual cortex (V1).

PURPOSE: To determine how the duration of early strabismus influences the severity of loss of disparity sensitivity in V1 neurons and the effects of extensive poststrabismus visual experience on the maintenance of functional binocular connections. METHODS: Concomitant strabismus was optically simulated in 10 rhesus monkeys using a prism-rearing procedure. The onset of strabismus was kept constant at 4 weeks of age and the duration was maintained for 2, 4, or 8 weeks. In one group of monkeys (infants), the neurophysiological experiments were conducted immediately after the period of rearing with prisms. In another group (adults), after the termination of the prism-rearing regimen at either 8 or 12 weeks of age, the monkeys were kept in a normal housing environment until maturity and behavioral testing was conducted before the recording experiments to determine the animal's monocular and binocular visual capacities. To assess the effects of the period of early strabismus on binocular interactions in V1, extracellular single-unit recording methods were used in anesthetized and paralyzed monkeys, and dichoptic sine-wave gratings were used as stimuli. RESULTS: In all strabismic monkeys, the sensitivity of V1 units to interocular spatial phase disparity (disparity sensitivity) was significantly reduced, and the prevalence of binocular suppression was higher than that found in age-matched control animals. Although 8 weeks of strabismus resulted in a slightly larger loss of disparity sensitivity, the overall effects of the duration of strabismus were surprisingly small in infant strabismic monkeys. After poststrabismus visual experience, a small but significantly higher degree of disparity sensitivity was noted in V1 if prism-rearing was terminated after 4 weeks of strabismus (i.e., at 8 weeks of age), but not after 8 weeks of strabismus (i.e., at 12 weeks of age). CONCLUSIONS: A brief period (2 weeks) of misalignment after the emergence of stereopsis is sufficient to drastically reduce the functional binocular connections in V1, and longer periods of strabismus result in little additional loss in disparity sensitivity. Clinically, these results suggest that taking corrective measures for infantile esotropes before the known onset age for stereopsis may be important for maintaining better binocular sensory function and better interocular alignment at later stages of development.

Aging↗

PubMed2003

Strabismus in infants of opiate-dependent mothers.

AIM: At a follow-up clinic for infants of opiate-dependent mothers it was noted that more infants than expected developed strabismus. This study aimed to assess the prevalence of strabismus and the need for active strabismus surveillance in this population. METHODS: Consecutive infants of opiate-dependent mothers born over an 18 mo period were recalled for ophthalmological assessment by an ophthalmologist and orthoptist. Those unable to attend were surveyed by telephone using a questionnaire. RESULTS: 49 (69%) of the 71 eligible infants were recalled at a mean age of 21 mo (range 6-39); 29 had a full ophthalmological examination and the remaining 20 completed the questionnaire only. Seven (14%) of the 49 recalled infants had strabismus on examination; 4 needed glasses or patching. A further seven (14%) had a history of intermittent strabismus but declined formal examination. Another child had significant hypermetropia without strabismus. The mean age at which strabismus was observed was 8.3 mo (range birth to 19 mo). The presence of strabismus was not significantly influenced by conditions at birth, maternal drug doses, family history or need for or duration of abstinence treatment. CONCLUSION: The rate of strabismus in infants of opiate-dependent mothers was at least 10 times that in the general population. As attendance at follow-up is often poor, paediatricians should be aware of the association to encourage opportunistic assessment and ophthalmological surveillance of this population.

Australia↗

PubMed2006

Chiari 1 malformation presenting as strabismus.

INTRODUCTION: Strabismus has been previously reported as a rare presenting feature of the Type 1 Chiari malformation. CASE REPORTS: We report a case series of twelve patients with Chiari 1 malformations with either strabismus or diplopia as part of their initial presentation. Ten patients had diplopia at the time of presentation, while 2 young children (ages 2 and 6) presented with esotropia without complaints of diplopia. Of the 10 patients with diplopia, 7 were constantly or frequently tropic while 3 had symptomatic phorias. One or more unusual features of the strabismus led to further investigations and the diagnosis of Chiari in these patients. The most common oculomotor disturbance was a comitant esotropia. Most patients were managed with prism glasses. One patient had strabismus surgery as primary treatment with early orthotropia. Three patients underwent neurosurgical decompression, with minimal improvement of their strabismus; one of these underwent subsequent successful strabismus surgery. CONCLUSIONS: Chiari 1 malformation may present with strabismus or diplopia as the major finding. Associated neurological features may be nonspecific (e.g., headache), subtle (e.g., gaze-evoked nystagmus), or delayed. Although neurosurgery may be required in some cases, primary strabismus management (surgical or prismatic correction) can be successful, particularly when strabismus is the lone (or sole specific) finding.

Adolescent↗

PubMedDate not supplied

[Metabolic changes in brain cortex related with the strabismus treatment. Preliminary results with SPECT].

OBJECTIVE: Our aim was to demonstrate metabolic changes occurring in brain cortex during strabismus treatment. MATERIAL AND METHODS: Single photon emission computed tomography (SPECT) of brain was made in patient with strabismus. The study only included congenital esotropia and excluded patients with other anomalies. Strabismus treatment was carried out with botulinum toxin or surgery. Brain SPECT was done prior to and after treatment. Changes were analyzed and related with strabismus response. RESULTS: We studied three children with congenital and variable esotropia for a total of three cases. In Case 1, basal SPECT showed hypoperfusion in left frontal lobe (7.38). Response to botulinum toxin was good for correcting strabismus and obtaining binocularity from third month. Control SPECT showed correction of perfusion of frontal lobe (-1.19). With Case 2, we observed hypoactivity in left parietal area (8.59); after botulinum treatment, strabismus was corrected and binocularity was demonstrated, while control SPECT showed increase of hypoactivity levels (5.95). Finally, in Case 3, strabismus was corrected at surgery with binocularity. Basal SPECT demonstrated very important hypoactivity in right hemisphere, especially in areas 3, 4, and 5 areas (-0.7, -3.71, and -11.09, respectively); in addition, positive changes after treatment were demonstrated (9.78, 6.44, and 3.22, respectively). CONCLUSIONS: Metabolic changes in brain cortex took place in congenital esotropia with SPECT. In all cases, brain SPECT could demonstrate changes after treatment with improvement of different areas, and good response of motor and sensorial state. This apparently is the first report concerning metabolic changes of brain cortex related with strabismus under treatment, and demonstrates the importance of brain cortex in genesis, evolution, and stability of visual functions and with regard to the failure of these in patients with strabismus.

Anti-Dyskinesia Agents↗

PubMed1995

Strabismus in very low birth weight and/or very preterm children: discrepancy between age of onset and start of treatment.

Very low birth weight (VLBW; less than 1500 g) and/or very preterm children are at risk for strabismus. However, the age of onset of strabismus is still unknown. The present study reports on the frequency of strabismus in 450 5-year-old children born with a birth weight of less than 1500 g and/or with a gestational age below 32 weeks. The age at which strabismus was initially diagnosed was determined retrospectively. At 5 years of age 65 of the at-risk children (14.4%) presented with strabismus. Fifteen of them (3%) had at that age not been referred to or treated by an ophthalmologist. At 3 years of age only 28 strabismic children were being treated; 7 at-risk children (2%) had been treated for strabismus before the end of the 1st year. These results were compared to those from a second study in which eye alignment was longitudinally examined in 194 VLBW children from 6 weeks until 12 months of (corrected) age and additionally in 65 of these children at the age of 2.5 years. At a first glance, the frequency of strabismus in the longitudinal study seemed rather stable during the first 2.5 years of life, with values varying between 14% and 18%. However, only a small percentage of misalignments which were noted at 6 weeks of age persisted until 2.5 years. On the other hand, if children had a misalignment at 9 months, strabismus was still present when they were reexamined at 1 and at 2.5 years of age.(ABSTRACT TRUNCATED AT 250 WORDS)

Age of Onset↗

PubMed2004

Strabismus surgery for adults: a report by the American Academy of Ophthalmology.

OBJECTIVE: To describe the effectiveness and safety of surgical treatment of adult patients with strabismus, and to review the reported functional benefits and complications of strabismus surgery for adults. METHODS: A literature search was conducted in September 2001. It was repeated and updated in April 2003, with retrieval of relevant citations. Panel members reviewed the articles and rated them according to their relevance to the topic and methodology. RESULTS: The literature search identified 49 reports that describe the surgical treatment of strabismus in adult patients and meet predetermined review criteria. Of these reports, 2 were of randomized controlled trials, and 1 addressed the primary objective of this review. In this randomized study of adults with strabismus, direct comparison of surgical correction with botulinum toxin A chemodenervation indicated that surgical treatment was superior to botulinum toxin A in realigning the eyes (76.9% vs. 29.4%, P = 0.027). Several large case series of adults with strabismus (level III evidence) with successful surgical realignment rates of 68% to 85% have been reported. Functional benefits of surgical treatment are reported in many patients. These include elimination of diplopia, development of binocular fusion, expansion of binocular visual fields, and improvement of head position. Surgical complications, including new, postoperative diplopia (1%-14%) or scleral perforation (0.8%-1.8%), occur in a minority of patients. Unplanned reoperations (subsequent strabismus procedures that were not anticipated as part of a staged treatment) were needed in up to 21% of patients in large case series of comitant strabismus, and in up to 50% of patients with thyroid ophthalmopathy. CONCLUSIONS: Despite the paucity of level I evidence from randomized controlled trials, the existing literature suggests that surgical treatment of adults with strabismus is safe and effective in improving ocular alignment. In many cases it improves visual function, based largely on level III evidence. Risks include unplanned reoperation, postoperative diplopia, and scleral perforation. Additional level I studies of surgical treatment of adult patients would help to document the effectiveness and substantiate the safety of this treatment.

Adult↗

PubMed2005

Latency of saccades, vergence, and combined movements in children with early onset convergent or divergent strabismus.

The goal of this study was to examine latency of horizontal eye movements in the natural space (saccades, vergence, and combined saccade-vergence movements) in children with early onset convergent or divergent strabismus. Ten children were tested (8-11 years old): three with divergent strabismus, seven with convergent strabismus. A paradigm was used to elicit pure lateral saccades at far and near distance, pure vergence (convergence and divergence) and saccades combined with vergence movements. Horizontal eye movements from both eyes were recorded simultaneously by a photoelectric device (Oculometer, Dr. Bouis). The latency of saccades (at far and near distance), of vergence (convergence and divergence), and of combined movements greatly varies among subjects and has tendency to be longer than that observed in normal children of matched age, however, these differences reach significance in only a few cases. Children with divergent strabismus and residual gross binocular vision show abnormally longer vergence latencies than children with convergent strabismus without binocular vision. The initiation of combined movements does not show a dominant pattern, such as preceding vergence, as is found in normal children. Finally, strabismus surgery has no major effect on latencies. We conclude that there is no overall deficiency in latencies of eye movements in 3D space in children with early onset strabismus. Most likely, monocular visual input can be efficient as normal binocular vision for vergence movements. In a few subjects with divergent strabismus and fragile, intermittent binocular vision, latencies can be abnormally long, just because of the fragile binocular input and/or attention effort needs to use it. The absence of a pattern of initiation similar to normal children could be due to attention and fixation capabilities.

Case-Control Studies↗

PubMed1999

Monocular horizontal OKN in observers with early- and late-onset strabismus.

Several reports on monocular optokinetic nystagmus (OKN) in observers with strabismus have found that asymmetry of OKN tends to occur in both eyes of observers with an early onset of strabismus but only in the deviating eye of those with a later onset of strabismus. Our objective was to quantify and compare the magnitude of the OKN asymmetry in each eye as a function of observer's age at onset of strabismus. We studied monocular OKN in ten observers with early-onset (up to 24 months of age), seven observers with late-onset (after 24 months of age) unilateral strabismus, and 12 normally sighted control observers. In the deviating eye, observers with early-onset strabismus showed large OKN asymmetries in favour of nasalward motion while observers with late-onset strabismus showed smaller OKN asymmetries in that eye. The majority of early- and late-onset observers showed near normal OKN in the non-deviating eye although the early-onset observers showed bilateral asymmetries more often. These findings may be due to both age at onset of strabismus and chronological age and are discussed in terms of the issue of plasticity or recovery of function.

Adolescent↗

PubMed1997

Strabismus surgery among aged medicare beneficiaries.

OBJECTIVES: The purpose of this study was to investigate the incidence of strabismus surgery among aged patients in the United States. METHODS: The Medicare Part B claims experience (physician professional fee billing) for 1995 was reviewed for the number of times each strabismus surgical procedure recognized in Physicians' Current Procedural Terminology (CPT) was performed. To determine the indications for the procedures that were performed, a 5% sample of claims was reviewed for the pertinent International Classification of Diseases, Ninth Revision, Clinical Modification, diagnostic codes. RESULTS: There were 27 million aged Medicare beneficiaries eligible for Part B benefits in 1995 in a fee-for-service setting. During that year physicians reported 9497 strabismus physician services. These represented 6585 separate procedures (CPT codes 67311 to 67343) and 277 botulinum toxin (Botox) injections for strabismus (CPT 67345) performed during 1995. Sixty-nine percent of the surgical procedures were for horizontal correction and 28% were for vertical correction. Adjustable sutures were used for only 1240 cases (1 9%). The add-on procedural code for reoperation surgery or surgery in the presence of restriction of the extraocular muscles was used in just 930 cases (14%). The most common diagnosis for horizontal surgery was exotropia. Paralytic strabismus and thyroid disease were identified for 17% of cases. Three percent of the diagnoses were inappropriate for the procedures performed and may have been reported in error. CONCLUSIONS: These data confirm a very low incidence of strabismus surgical procedures (2/10,000) and injections (1/100,000) among aged Medicare beneficiaries. The strabismus surgery was most often performed to repair a horizontal deviation. The adjustable suture technique was used infrequently. These data may be extrapolated into the future to aid in determining the strabismus services that will be needed early in the next century.

Aged↗

PubMed2002

Strabismus surgery for large-angle cyclotorsion after macular translocation surgery.

PURPOSE: We report the results of a new strabismus surgical procedure to address the large-angle cyclotorsion induced by macular translocation surgery for severe age-related macular degeneration. METHODS: The strabismus surgery described is a modification of earlier-described surgery(1) and was performed for symptomatic incyclotorsion measuring 20 degrees or more (by Maddox rod testing) after macular translocation. Surgery included superior oblique tenotomy and inferior oblique advancement, with transposition of the lateral and medial recti to the insertions of the superior and inferior recti, respectively, in the affected eyes. Minimum follow-up time was 6 weeks. RESULTS: Fifteen patients (15 eyes) had macular translocation surgery with incyclotorsion of 20 degrees or more. Mean incyclotorsion after macular translocation (36.1 +/- 9.4 degrees; range, 20-55) was reduced to 1.5 +/- 6.4 degrees after strabismus surgery (P <.0001), with 2 overcorrections and no surgical complications. Mean follow-up time was 24.8 +/- 13.4 weeks. All patients showed a hypertropia of the fellow eye. The mean pre-op hypertropia of 22 +/- 8 PD was reduced to 3 +/- 9 PD after strabismus surgery (P <.0001). The mean exotropia was minimally altered by strabismus surgery (21 +/- 10 PD pre vs 17 +/- 8 PD postop). All patients were symptomatic prior to strabismus surgery: 4 of 15 patients with "tilt" (objects appearing subjectively rotated with respect to their true orientation); 2 of 15 patients with diplopia; and 9 of 15 patients with both. Postoperatively, 7 patients had residual milder symptoms: tilt, 2 patients; diplopia, 3 patients; and both, 2 patients. Two patients required additional muscle surgery (on the fellow eye) for persistent symptoms. No patient showed binocular function (stereopsis or motor fusion) after macular translocation, either before or following strabismus surgery for cyclotorsion. CONCLUSION: The strabismus surgery described is effective at reducing the large degree of cyclotorsion (>or= 20 degrees) often resulting from macular translocation surgery, but does not allow reestablishment of binocular function.

Aged↗

PubMed2003

Strabismus following endoscopic orbital decompression for thyroid eye disease.

Endoscopic orbital decompression may be used to treat disfiguring proptosis or sight threatening optic nerve compression in patients with thyroid eye disease. Strabismus is common in thyroid eye disease and frequently follows decompression surgery. We retrospectively reviewed patients undergoing endoscopic decompression for thyroid eye disease, by a single surgeon, from 1994 to 2000. Twenty-three patients (21 female, 2 male) were identified with a mean age of 47.5 years. At presentation, 21 patients had proptosis, 8 optic nerve compression (2 without proptosis) and 11 strabismus (9 complained of diplopia) with a mean BSV score of 24.5 before decompression. Forty orbits were decompressed with a mean decrease in proptosis of 3.3 mm. Following decompression, the mean BSV score was 25, and 17 patients had manifest strabismus in primary gaze (3 at near only) of whom 10 had pre-existing strabismus. Five patients had new diplopia (22%). Eleven patients ultimately required strabismus surgery of whom 8 had manifest strabismus before decompression. Following strabismus surgery, the mean BSV score was 37. The final BSV score for those not requiring strabismus surgery was 29. Mean follow-up was 28 months. Endoscopic orbital decompression can effectively treat disfiguring proptosis. Diplopia is a common complication, but pre-existing diplopia may improve.

Adult↗

PubMed2005

The prevalence of strabismus and amblyopia in Japanese elementary school children.

BACKGROUND: The purpose of this study is to elucidate the prevalence of strabismus and amblyopia in a large population of Japanese elementary school children, from Grade 1 to Grade 6, ages ranging from 6 to 12 years. The School Health Law requires that all pupils in Grade 1 to Grade 6 be examined for vision and eye problems. Visual acuity testing is done by school teachers and eye disease screening by school ophthalmologists. Pupils with suspected ocular diseases are further examined by extramural ophthalmologists and the results reported back to the schools. The schools then summarize and send uncorrected visual acuity and ocular disease incidence, together with other health statistics, to the municipal education committees. The data are forwarded to the Prefecture Governments and finally submitted to the Education Ministry of the Central Government. Both the Prefecture Governments and the Education Ministry publicize the school health statistics on their websites. The prevalence of strabismus and amblyopia remains unknown from these data because both diagnoses are included under the heading, eye diseases. METHODS: Questionnaires asking about the numbers of children with different types of strabismus and amblyopia were sent to all elementary schools in Okayama Prefecture and the results were summarized. RESULTS: The number of children covered by the return of questionnaires was 86,531 (76.4%) of 113,254 total pupils in Grade 1 to Grade 6 in Okayama Prefecture in the year 2003. The total numbers of children with strabismus and amblyopia were 1,112 (1.28%) and 125 (0.14%), respectively. The numbers of children with any type of exotropia and any type of esotropia were 602 (0.69%) and 245 (0.28%), respectively. The major types of strabismus and amblyopia were intermittent exotropia in 109 children (0.12%), accommodative esotropia in 19 children (0.02%), anisometropic amblyopia in 23 children (0.03%), and ametropic amblyopia in 12 children (0.01%). The number of children with strabismus of unknown type was 245 (0.28%) while the number of children with amblyopia of unknown type was 81 (0.09%). CONCLUSIONS: The prevalence rates of strabismus and amblyopia in this population of Japanese elementary school children were lower than those reported in Western countries. The exotropia/esotropia ratio were increased in comparison with past studies in Japan. The school eye doctors need to be more diligent in identifying and diagnosing various types of strabismus and amblyopia in order to contribute to the school vision screening program already in place in Japan

Amblyopia↗

PubMed2006

Use of botulinum toxin in strabismus.

PURPOSE OF REVIEW: The history, pharmacology, indications, complications, and success rates of botulinum administration are discussed in this review as they relate to strabismus and associated conditions. RECENT FINDINGS: Botulinum has been used to treat strabismus and a variety of other ocular conditions for over three decades. Alan Scott initially investigated extraocular muscle paralysis by botulinum injection in 1973, and in the ensuing years botulinum has been evaluated as a treatment for horizontal and vertical strabismus, nystagmus, dissociated vertical deviation, sensory strabismus, ophthalmoplegia, and paradoxical diplopia. SUMMARY: Botulinum administration is a strabismus treatment option that may be considered for some strabismus patients; in select cases botulinum is a reasonable and preferable alternative to surgery. Current clinical recommendations regarding botulinum should be considered in the context of the existing comparative studies that are summarized in this review. Since there are very limited data directly comparing the success rates of botulinum with standard strabismus surgery, additional, well designed prospective studies are needed. Data from such studies would enable recommendations for strabismus management to be formulated using an evidence-based approach.

Botulinum Toxins, Type A↗

PubMed1980

Experimental strabismus in the kitten.

1. We have examined the relative roles of visual and nonvisual input to striate cortex cells in causing the breakdown of binocularity produced by brief periods of visual-axis misalignment in kittens. 2. In the first study, the binocularity of single neurons recorded from the striate cortex was assessed in kittens reared with either surgical or optical strabismus. Surgical strabismus was induced by performing a unilateral medial rectus tenotomy, and optical strabismus by means of goggles that held prisms of equal power before the two eyes with their bases oriented in opposite directions. The loss of functional binocular connections was of comparable severity in these two groups of kittens. Control kittens, reared wearing goggles containing prisms whose bases were oriented in the same direction, showed normal levels of binocularity. 3. In the second experiment, normal kittens were given a surgical strabismus at around 1 mo of age and kept in total darkness for 2 days, 2 wk, or 4 wk. Cortical binocularity was normal in these kittens. 4. Finally, a group of kittens was reared in the illuminated colony with a symmetric surgical strabismus (bilateral medial rectus tenotomy). These kittens suffered a severe loss in cortical binocularity that was comparable to that seen in control kittens reared with asymmetric (unilateral) strabismus. 5. We conclude that altered visual input caused by misregister of the images falling in the two eyes is necessary and almost certainly sufficient to cause breakdown of cortical binocularity in kittens exposed to brief periods of divergent strabismus and that, when strabismus is induced surgically, this loss of binocularity is not dependent on the symmetry of the surgical manipulation; we thus find no evidence for a special role of afferents from the extraocular muscles in producing this effect.

Animals↗

PubMed2005

[Strabismus surgical treatment: technical-economic evaluation].

PURPOSE: To evaluate, from the economic and technical point of view, the surgical treatment of strabismus. METHODS: A retrospective survey of available consecutive medical charts from the Altino Ventura Foundation-Recife/PE, Brazil was performed. Data on 100 patients who underwent strabismus surgery (from January of 2001 to February of 2003) and 100 patients who underwent cataract surgery (January of 2003) were analyzed. The times to performed these surgical procedures were observed. The times to accomplish strabismus surgeries were compared to those of cataract surgeries. In addition the variability of time among different strabismus surgeries was also observed. RESULTS: Surgical mean time for strabismus correction was longer than that for cataract surgery (77.3+/-27.6 min versus 58.3+/-12.7 min; p<0.0001). A significant variability in time to accomplish strabismus surgeries was also observed. In the case of intervention in up to two muscles, mean time was less than in the case of intervention in more than two muscles (66.0+/-16.6 min versus 97.5+/-31.7 min; p<0.0001). CONCLUSION: Longer surgical time of strabismus surgeries as compared to cataract surgeries gives support to the idea that the medical remuneration for strabismus surgery should be, at least, equivalent to that of cataract surgery. In addition, the fact of surgical mean time being so variable, suggests that this procedure should have a different remuneration.

Adolescent↗

PubMed2003

[Clinical analysis of the diplopia and strabismus after ophthalmic surgeries].

OBJECTIVE: To explore the mechanism and therapy of strabismus secondary to ophthalmic surgeries. METHODS: 79 cases of postoperative secondary strabismus were examined for eye position, eyeball movement, diplopia and ocular muscle traction test. Strabotomies were performed in some of the cases. Their involved extrocular muscle conditions were examined during the surgery. RESULTS: The cases of strabismus in the series were secondary to surgery of retinal detachment (38.0%), cataract extraction (31.7%), orbital surgery (13.9%), and other ophthalmic surgeries such as glaucoma, pterygium and blephatoptosis. Some cases secondary to surgery of retinal detachment and cataract extraction didn't recover in more than 6 months after surgery. The traction tests of involved muscles in some cases were positive. Fibrosis of the involved ocular muscles and adhesion of involved ocular muscles to conjunctiva, sclera and explants were found during strabotomies. Strabismus secondary to orbital surgery mainly showed impeding movement of eyeball. Strabismus secondary to pterygium mainly related to injury of the medial rectus operations. Strabismus secondary to glaucoma surgery recovered spontaneously in 2 - 14 days after operations. CONCLUSIONS: Intraocular or external ophthalmic surgeries can cause secondary strabismus. The mechanism is primarily due to direct injury of the extraocular muscles, impeding movement and mechanical compression to the eyeball. Surgeons should pay more attention for those side effects, and take effective therapy to prevent and treat iatrogenic strabismus.

Adolescent↗

PubMed1979

Saccadic intrusions in strabismus.

Fixational eye movements were studied to determine the presence of and to quantify saccadic intrusions under monocular and binocular viewing conditions in subjects with intermittent strabismus, amblyopia without stabismus, or constant strabismus amblyopia. Saccadic intrusions were present under most test conditions in intermittent strabismus, were rarely observed in amblyopia without strabismus, and were prominent during monocular fixation with the amblyopic eye in constant strabismus anblyopia. This suggests that the presence of saccadic intrusions was related to strabismus and not amblyopia. There was no relationship between saccadic intrusion amplitude and visual acuity. Two possible mechanisms for producing intrusions are abnormally rapid regional visual adaptation and strabismus-induced fixation degradation.

Adolescent↗