|Year : 2013 | Volume
| Issue : 1 | Page : 24-28
Surgical outcomes following ocular re-alignment in various types of squints
Vidya Hegde1, Anupama Bappal1, Neelam Puthran2
1 Department of Ophthalmology, Yenepoya Medical College, Deralakatte, Mangalore, India
2 Department of Ophthalmology, Bharatiya Vidyapeet Medical College, Pune, India
|Date of Web Publication||21-Jun-2013|
Department of Ophthalmology Yenepoya Medical College, Deralakatte Mangalore - 575 018
Source of Support: None, Conflict of Interest: None
Background: Strabismus is one of the causes for visual impairment in childhood. It affects the development of binocular single vision. Therefore, early detection and timely management of strabismus is important. Aim: This study was aimed to describe types of strabismus patients presenting to a tertiary care center and the various management modalities including the surgical outcomes of ocular re-alignment Materials and Methods: Retrospective chart analysis of all patients with strabismus in any age group over a period of 5 years. Patients with cerebral palsy were excluded from this study. Surgical outcomes were graded as good if the eyes were orthophoric post-operatively, satisfactory if there was a residual squint of less than 10 degrees, and it was considered to be a poor outcome if the patients were left with more than 10 degrees of residual squint. Results: Chart analysis of 53 cases with strabismus comprising of 33 males and 20 females was done. The mean age of patients was 25 years. Thirty-two (60%) cases had exotropia, and 14 (26%) had esotropia. Three cases were of congenital superior oblique palsy, and one case was of lateral rectus palsy. Duane syndrome type I was seen in four cases. Of the 38 (72%) patients who were advised surgical correction, only 20 individuals underwent surgery. Reasons for refusal of surgery varied from fear factor to financial constraints and a disregard for cosmesis. Surgeries had been performed on both children (7) as well as adults (13). Seventy-five percent of the operated patients had exotropia. Eighteen patients underwent single-staged surgery. Bilateral recessions were the most common type of surgery noted in this study. Fifty percent of them remained orthophoric up to one year of post-operative follow up. Conclusion: Exotropia was the most common type of strabismus observed in this study. Successful ocular re-alignment was seen in majority of the patients following a single-stage procedure. Greater effort needs to be made to educate the public on need for early diagnosis and management.
Keywords: Ocular re-alignment, surgical outcome, types of strabismus
|How to cite this article:|
Hegde V, Bappal A, Puthran N. Surgical outcomes following ocular re-alignment in various types of squints. Arch Med Health Sci 2013;1:24-8
| Introduction|| |
Strabismus and amblyopia are the commonest ophthalmic problems affecting young children. The prevalence of strabismus worldwide is reported to vary from 1.3% to 5.7% of all children,  although a study from southern India has shown a lower prevalence of 0.7%.  The presence of strabismus adversely affects the development of binocular single vision. Its early detection is, therefore, important for both, the restoration of normal ocular alignment and the establishment of binocular single vision  preferably at early age.
Management of strabismus includes correction of refractive errors, management of any co-existing amblyopia, and surgery of one or more extra ocular muscles to re-align the eyes. The benefits of surgical correction include elimination of diplopia, restoration of binocular single vision, and improvement of cosmesis and psychosocial status. It has long been thought that if strabismus correction is delayed into adulthood, improvement in visual function does not occur despite proper re-alignment of the eyes. However, some reports in the past two decades have indicated the possibility of good surgical outcomes, and significant improvements of central and peripheral binocular visual function even in adult patients. ,, The present study is a historical review to determine the types of strabismus, the various management modalities offered to both children and adults, as well as the outcomes of surgical re-alignment of the eyes.
| Materials and Methods|| |
A retrospective chart analysis of all patients with strabismus managed at a tertiary eye care center from January 2005 to December 2009 was performed. The cases were identified using the International Classification of Diseases (ICD-9-CM Code 378) coding system, and case documents were retrieved from the hospital medical records department after obtaining ethical clearance from institutional ethics committee.
All patients with strabismus in any age group, whose documents were available for review, were included. Cases of cerebral palsy with strabismus were excluded from the study. A total of 53 case records were reviewed.
The following data were recorded: Age of onset of strabismus, type of strabismus, range of ocular motility, best corrected visual acuity (BCVA), and Worth four dot test. The amount of deviation, as assessed by prism bar cover test for distance and near, as well as Krimsky test, was noted. The forced duction and force generation tests were done in the outpatient department except in children, which were done in the operation theater. The type of management, whether surgical or non-surgical, was also noted. In those patients who underwent surgery, the type of surgery, whether single-staged or multi-staged procedures, number of muscles operated upon, duration of post-operative follow up, and the postoperative motor alignment were recorded. Significant anterior segment and ophthalmoscopic examination findings, if any, were also noted. The reason for refusal of surgery is also noted. Surgeries were performed by four different surgeons.
| Results|| |
Of the 53 charts studied, 33 (62 %) were of male patients and 20 (38%) were of females. The age group ranged from 11 months to 77 years with a mean being 25 years [Table 1]. The period of follow up ranged from 6 weeks to 1 year. The pattern distributions of strabismus are shown in [Table 2]. There were 4 cases of paralytic strabismus, of which 3 were due to congenital superior oblique palsy and 1 was an acute onset of lateral rectus palsy.
With regard to age of onset of strabismus, 14 (26%) patients had strabismus at birth. Squints had been noticed in childhood in 19 (36%) patients, although no mention was made about whether it was in early or late childhood. The earliest onsets recorded were at 3 months of age in one patient and at 2 years age in another. There were no significant precipitating events in any of the childhood onset squints. In the remaining 18 (34%) cases, the onset of strabismus was not precisely known. Diplopia was the presenting complaint in one patient who had adulthood onset of uniocular lateral rectus palsy.
A total of 13 patients (25%) were emmetropes. Best Corrected Visual Acuity (BCVA) of 6/6 was present in 45 of 106 eyes (42%) while 10 eyes (9%) had BCVA of =/< 3/60 [Table 3]. The different types of refractive errors observed are as shown in the [Table 4]. Four patients were prescribed glasses to correct refractive error associated with squint. In addition, there was one case of accommodative esotropia who was also managed with spectacles alone. In this study, 7 (13%) of the strabismic patients had anisometropia. Contact lenses were prescribed for 4 of them and spectacles for 3. Amblyopia was present in 9 cases (17%), of which 2 cases were of strabismic amblyopia and 7 of anisometropic amblyopia. Three patients between 8 and 12 years of age had been managed with occlusion therapy for amblyopia.
Ocular motility abnormalities were seen in 4 cases of Duane's syndrome type I, 1 case of lateral rectus palsy and in 3 cases of superior oblique palsy. Inferior oblique over action was seen in 6 patients, one of whom had associated Dissociated Vertical Deviation (DVD), while one patient had DVD alone. V phenomenon was observed in 2 cases, and A phenomenon in 1 patient.
Of the 38 (72%) patients who were advised surgical correction, only 20 individuals consented to undergo surgery. The youngest patient who underwent surgical correction was 6 year old and the oldest was 57 years (Mean of 23.6 years). A majority (75%) of the 20 patients in this series underwent surgery for exodeviations. Of these, 11 patients had basic exotropia and one each had pseudo divergence excess and intermittent exotropia. Only 2 cases required multi-staged surgeries. The remaining 18 patients underwent single-stage surgery. Bilateral recessions were done in 7 patients, while 6 patients underwent single eye recess / resect procedures. Solitary inferior oblique anterior transposition was done in 2 patients. Surgical outcomes were graded as good if the eyes were orthophoric post-operatively, satisfactory if there was a residual squint of less than 10 degrees, and it was considered to be a poor outcome if the patients were left with more than 10 degrees of residual squint. Post-operative ocular alignment with orthophoria was attained in 10 individuals [Table 5]. Good surgical outcome was seen in 47% of patients with exotropia and 67% of patients with esotropia. All these patients were followed up post-operatively for a year.
Eighteen patients refused any surgical intervention despite counseling, while surgery was not advised in 10 cases (19%) due to the presence of conditions such as Duane's retraction syndrome with orthophoria (4), microphthalmos (1), strabismus due to pathological changes in the fundus with poor vision (3), and paralytic strabismus of acute onset (1). Diplopia, resulting from the acute onset of lateral rectus palsy, was managed conservatively with patching of the deviating eye. One patient, a case of congenital superior oblique palsy, was lost for follow up.
| Discussion|| |
There is a wide variation in the pattern distribution of strabismus in different parts of the world. Generally, esotropia is the most common type of strabismus seen, especially in younger age groups, , although exotropia has been reported to be commoner in non-white populations. , In a study on the prevalence of visual impairment in school children in southern India, it was found that there was a greater preponderance of exotropia (70%) as compared to esotropia (30%).  Studies by Rachael and Jenkins have shown that intensity and duration of exposure to sunlight may play a role in pattern distribution of strabismus along with racial factors.  Thus, higher the intensity of light, higher the frequency of exotropia. In our study, which involved a population belonged to a coastal region of southern India where the sunlight is harsh, a similar prevalence of exotropia (60%) has been noted.
Regarding vertical squints, Tollefson and co-workers reported the overall cumulative incidence of childhood hypertropia to be 0.26% with a significant decrease in incidence with increasing age.  Kornder et al, reported prevalence of hypertropia to be 0.09% among 1074 children from 6 to 30 months of age.  Friedman et al, found hypertropia to occur in only 0.06%.  In our study, 6% of patients were diagnosed as hypertropes. However, this higher number may be due to the small sample size.
The gender distribution regarding strabismus patients has been shown to have a female preponderance, according to various studies done in Africa. , However, the majority of patients with strabismus in our study were males (62%). This is in consonance with the findings of Azonobi et al, from their study in Nigeria.  We have observed that most cases of strabismus were noted in childhood and only one of the two cases of paralytic squint had an acute onset in adulthood.
A little over half (53%) of the patients with squints in the present series underwent surgery. Most of them were exotropes. Fifty percent of the patients had a good surgical outcome and remained orthophoric till one year of post-operative follow up. Satisfactory outcomes were achieved in 7 cases, while 3 cases had poor surgical outcomes.
In our series, it was observed that the vast majority (85%) of cases (17 of the 20 operated cases) were of large angle squints, i.e. deviations greater than 40 prism diopters. The largest deviation dealt with surgically was 80 prism diopters. A good surgical outcome had been obtained in 8 of these large angle squints. Scott et al, have recommended that for larger angles of deviation, the surgical objective should be a small residual deviation rather than orthophoria. 
Bilateral recessions were the most common type of surgery noted in this study. Sixty-five percent patients had undergone surgery involving two horizontal rectus muscles, and in 10% of patients, surgery was confined to only a single muscle, i.e. the inferior oblique. Surgeries had been performed on both children (7) as well as on adults (13). The presence of strabismus adversely affects many aspects of patients' lives including finding a partner, job prospects, and interaction with peers. They have a lack of confidence and low self-esteem. The benefits of correcting strabismus in adults include improvement in psychosocial functioning and better opportunity for employment and economic success.  Of the 38 patients, who were advised surgical correction of their squints, 18 had refused any intervention for strabismus. Fear of surgery and financial constraints are often the reason for refusal of surgery. In India, it is a common experience that persons with squints often consider surgical correction only in an effort to improve their marriage prospects. Otherwise, there appears to be a tendency to disregard cosmesis, especially if the squint has not proved to be a hindrance to marriage. This has been reiterated in a study about Perceptions of Eye Diseases and Eye Care Needs of Children among Parents in Rural South India. 
Various factors which influence the surgical outcome of primary exotropia include age at onset, age at time of surgery, interval between presentation and surgery, and the pre-operative angle of deviation. ,,,, Better surgical response is observed with younger patients, poorer visual acuity, less myopic refraction, and less anisometropia. , Scott et al, found the response to surgery to be negatively correlated to age at time of surgery and positively correlated to the pre-operative angle of deviation.  In our study, good surgical outcome was seen in 10 young patients and 2 of them were amblyopes.
The Keelung Ann-Lo Community ocular survey, 1993-1995 in Taiwan, has shown that many parents are not aware of the need for timely treatment of strabismus,  suggesting that childhood strabismus is often neglected by the public at large. This highlights the need for a greater emphasis on health education at the community level. The present series showed the distribution of strabismus in wider age group. About 53% had presented to an ophthalmologist after the age of 20 years. Sixty-five percent of people who underwent surgical correction were of more than 20 years of age.
Limitations of this study include :- 1) A small sample size. It is likely that in the rural population served by our institution, many individuals with squints do not seek ophthalmic consultation as it is not considered to be a priority health matter. 2) This study has not addressed the issue of functional gain, and only anatomical improvements have been evaluated. 3) Variations in the surgical outcome may be attributable, in part, to the fact that different surgeons had performed the surgeries.
| Conclusion|| |
This retrospective study is unique as it gives a panoramic view of various patterns of strabismus and its management, across all age groups of patients presenting at tertiary medical college hospital. Our study confirms the finding that outward deviations are commoner in the tropics and successful ocular re-alignment can be achieved in most cases with single-stage surgery. Good surgical and functional outcome is reported in pediatric as well as adult patients. However, patients' perception and willingness for surgery play a significant role in them opting for surgery. Hence, effort has to be directed towards educating the community and patient counseling to motivate the patient to undergo early strabismus treatment.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]