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Year : 2022  |  Volume : 10  |  Issue : 1  |  Page : 27-32

Profile of orthoptic clinic patients at a tertiary care Government Medical University in North India: A 6-year review

Department of Ophthalmology, King George's Medical University, Lucknow, Uttar Pradesh, India

Date of Submission25-Aug-2021
Date of Decision24-Nov-2021
Date of Acceptance02-Dec-2021
Date of Web Publication3-Feb-2022

Correspondence Address:
Siddharth Agrawal
Department of Ophthalmology, King George's Medical University, Lucknow - 226 003, Uttar Pradesh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jcor.jcor_123_21

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Aim: This study aims to study clinicodemographic profile of patients presenting to orthoptic clinic over the previous 6 years. Methods: Records of all new patients registered at the orthoptic clinic over 6 years' (January 1, 2014, to December 31 2019) were retrieved. Details of patient demographics, clinical presentation and management were studied in this hospital-based descriptive observational study after obtaining institutional ethical clearance. Records that were incomplete and those of patients with a history of strabismus surgery at presentation were excluded from analysis. Exact binomial confidence intervals (CIs) were calculated for the estimates of proportion. The results were reported as percentage (95% CIs). Descriptive statistics were used for subtypes of strabismus and amblyopia. Results: Out of 1548 patients, 896 were male (57.88%) and 652 (42.12%) were female. Mean age at presentation was 18.53 ± 10.41 years. Comitant strabismus was seen in 1083 (69.96%) and incomitant in 203 (13.11%). Among comitant deviations exotropia (XT) was commonest (n = 511, 47.18%), 6th nerve palsy (34%) was the most common cause among incomitant deviations, Duane retraction syndrome (DRS) constituted 24% of restrictive strabismus and amblyopia was present in 16.71% (n = 331) of patients. The left eye (LE) was more frequently involved in unilateral amblyopia (P < 0.0001). Conclusions: In our study, male to female ratio was 1.37. XT, 6th Nerve palsy, and DRS were the commonest types of comitant, paralytic and restrictive deviations respectively. Prevalence and severity of different types of amblyopia have also been described.

Keywords: Amblyopia, clinical profile of strabismus, comitant strabismus, incomitant strabismus

How to cite this article:
Chahal V, Singh V, Singh J, Kaur G, Srivastava RM, Agrawal S. Profile of orthoptic clinic patients at a tertiary care Government Medical University in North India: A 6-year review. J Clin Ophthalmol Res 2022;10:27-32

How to cite this URL:
Chahal V, Singh V, Singh J, Kaur G, Srivastava RM, Agrawal S. Profile of orthoptic clinic patients at a tertiary care Government Medical University in North India: A 6-year review. J Clin Ophthalmol Res [serial online] 2022 [cited 2023 Jun 8];10:27-32. Available from: https://www.jcor.in/text.asp?2022/10/1/27/337187

Strabismus is one of the most busy subspecialty in ophthalmology and the unpredictable outcome of the treatment coupled with the patients' expectations make it highly challenging. The abnormal ocular alignment may be the cause or effect of an impaired sensory system and it not only limits functionality but also puts a social stigma on an affected individual creating performance stress.[1],[2] Early diagnosis and timely treatment of conditions affecting the sensory or motor system of ocular alignment is of utmost importance in children. An orthoptic clinic is the place where patients with motor or sensory abnormality of the eyes are examined and advised.

The orthoptic clinic of our medical university serves as a referral center for various other departments and hospitals for patients seeking care for ocular deviations and associated complaints including amblyopia. Understanding the profile of patients attended at the clinic would indicate the demographics, disease burden and help in suggesting lacunae in the management of same. It is well reported that the prevalence of strabismus, its various subtypes, and amblyopia varies in different populations, however to the best of our knowledge (PubMed search on July 5, 2020) a single Indian study has tried to estimate the disease burden over a 1 year period.[3] We have retrieved and retrospectively analyzed 6-year records of the clinic in this study.

  Methods Top

Records of all new patients registered at the orthoptic clinic over a 6-year period (January 01, 2014 to December 31, 2019) were retrieved and details of patient demographics, clinical presentation, and management were studied in this hospital-based descriptive observational study after obtaining institutional ethical clearance. Records that were incomplete and those of patients with a history of strabismus surgery at presentation were excluded from the analysis.

Exact binomial confidence intervals (CIs) were calculated for the estimates of proportion. The results were reported as percentage (95% CIs). Descriptive statistics were used for subtypes of strabismus and amblyopia. MedCalc Statistical software version 19.4.1 was used for analysis.

  Results Top

A total of 1691 new patients were registered at orthoptic clinic over the 6-year period. New patients registered in the Ophthalmology outpatient department (OPD) during the same period were 160,466. So, about 1% of all OPD patients were registered at the clinic. One hundred and forty-three (8%) records were excluded from analysis and the clinic-demographic profile of the remaining 1548 patients was studied.

Male (n = 896, 57.88%) to female (n = 652, 42.12%) ratio was 1.37 (P < 0.01). Mean age at the time of presentation in total population was 18.53 ± 10.41 years. Comitant strabismus was seen in 1083 (69.96% [95% CI, 68.89–71.11]) patients followed by incomitant in 203 (13.11% [95% CI, 11.99–14.21]) patients (P < 0.0001). 145 (9.36% [95% CI, 8.25–10.47]) patients had no deviation and were either incorrect referrals or sent for amblyopia management. Out of 1548 patients 474 (30.62% [95% CI, 25.25–35.99]) patients were advised surgical management.

In the comitant group (1083 patients), exotropia (XT) was the predominant deviation in 511 (47.18%) followed by esotropia (ET) in 493 (45.52%) (P = 0.42). 203 (13.1%) patients had incomitant deviation of which 59 had congenital/infantile (29.06%) onset and 144 (70.94%) had delayed onset. Among incomitant strabismus, 128 (63.05%) had paralytic strabismus of which 69 (53.90%) had 6th nerve palsy, 40 (31.25%) had 3rd nerve palsy and 19 (9.36%) had 4th nerve palsy. 75 (36.95%) of patients had restrictive strabismus. Duane retraction syndrome (DRS) (n = 18), Brown syndrome (n = 6), trauma (n = 21), and thyroid ophthalmopathy (n = 11) were the common causes of restrictive deviations [Table 1].
Table 1: Clinicodemographic profile of patients

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[Table 2] summarizes the details of patients with comitant deviations. Out of 511 XT, 273 (53.42%) were of basic, 49 (9.59%) were of divergence excess, 24 (4.70%) were of convergence insufficiency and 106 (20.74%) were of simulated divergence excess subtypes, respectively. Among all XT, 311 (60.86%) were intermittent. Among ET, 191 (38.74%) had infantile ET, followed by accommodative ET in 146 (29.61%). ET more frequently had infantile-onset compared to XT (41% vs. 7% [P = 0.0001]) and also presented early (10.76 ± 8.65 years vs. 14.12 ± 11.48 years [P < 0.0001]). Fifteen patients had primary vertical deviation and 64 had it in association with horizontal deviations.
Table 2: Details of comitant deviations

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[Table 3] details patients with amblyopia which was present in 331 (16.71%) patients. Majority of the amblyopes were unilateral (n = 253, 76.43%) with involvement of the left eye (LE) (P < 0.0001). Most frequently encountered subtype was strabismic amblyopia (n = 202, 61.02%) followed by refractive (n = 78, 23.56%), stimulus deprivation (n = 37, 11.17%) and mixed mechanism (n = 14, 4.23%). ET (n = 98, 48.51%) was the most common subtype among strabismic amblyopes, hypermetropia was the most frequent associated refractive error (n = 134, 40.48%) (P = 0.01) and stimulus deprivation had the densest amblyopia (Mean LogMAR of the worse eye ± SD was 1.07 ± 0.77). The severity of amblyopia was statistically comparable between ET versus XT (P = 0.285) and anisometropia versus ammetropia (P = 0.530).
Table 3: Details of patients with amblyopia

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  Discussion Top

This is the first tertiary care hospital-based Indian study covering 6-year clinicodemographic profile of orthoptic clinic patients including subtypes of strabismus and amblyopia. Another study reports cases seen over 1 year and does not report subtypes of esotropia, XT, restrictive or paralytic deviations.[3] It also doesn't mention the severity of amblyopia in different subgroups, an issue that we have addressed.[3] The frequency of these subtypes varies in different reports and the present study provides their details in north India.[4],[5],[6],[7]

The male to female ratio and the increased frequency of comitant deviations in this report is similar to other studies[3],[8] Higher percentage of male patients in studies from India, unlike those from developed nations is probably due to unfortunate trend of greater concern for male children in our society.[3],[9] We have reported an almost equal incidence of ET and XT (P = 0.4221) in comitant group unlike reports from the temperate regions which report a higher incidence of ET and those from tropical areas which have more of XT.[3],[4],[5] This is probably because our region experiences summer (up to 45°C) and winters (up to 1.5°C) for an equal duration. Similar results were found in Baltimore Pediatric Eye Disease Study which showed a near equal incidence of ET and XT.[4] It is noteworthy that although on different latitude (39° N for Baltimore and 26° N for Lucknow) the region has subtropical weather, very similar to what we experience in our region.[10] Hence, not only distance from equator as has been earlier suggested but also the climate, sunlight, and obviously the ethnicity of the population have a role in the frequency of subtypes.[7],[11]

Among ET, essential infantile ET was the most common subtype followed by accommodative ET as has also been reported earlier.[12],[13] Accommodative ET was seen less frequently by us compared to others probably because most cases of refractive accommodative ET were treated at secondary level and those not corrected by glasses referred to tertiary center.[14] Among XT, basic and divergence excess were the most frequent subtypes similar to earlier reports.[15],[16] 60% of XT were intermittent, suggesting timely presentation of these patients. About 6% of all horizontal comitant deviations had associated vertical component. This is similar to the occurrence of A-V patterns reported in a study from the same region.[3]

Among paralytic deviations, sixth nerve palsy (n = 69, 33.99%) was the most frequent and fourth nerve the least (n = 19, 9.36%) unlike the report by Holmes JM probably because the latter report is limited only pediatric age group.[17] About one-fourth of all patients with incomitant deviations had their disease onset in infancy. The mean age of the patients also demonstrated that children and young adults are affected primarily as has been reported elsewhere.[18]

About 30% of all the patients and 39% of those with comitant deviations were advised surgery. Others either did not require surgery or were not expected to benefit from it (e.g., complete third nerve palsy). As in the previous reports, surgical rate is influenced by the heterogeneity of the study population, patients willing to accept small deviations, and availability of options like botulinum toxin.[19] This observation that 70% were managed nonsurgically suggests the future possibility of them being managed at a secondary level hospital.

About 21% of all patients and 15% of those with strabismus had amblyopia similar to the findings of other studies.[3],[20] Strabismic amblyopia was the most frequent and it was commoner and more profound in ET (P = 0.0007). ET is more frequently associated as it has an earlier onset and stable deviation, unlike XT which presents later and is intermittent initially.[20] Anisometropic amblyopia was next in frequency and was profound in anisohypermetropia. Amblyopia was less severe in ammetropia compared to anisometropia and can be explained by the concept differentiation of binocularly innervated lateral geniculate nucleus in favor of normal eye in anisometropia.[21] Hypermetropia was more frequently associated with amblyopia as myopes usually enjoy clear near vision. As expected densest amblyopia was seen in stimulus deprivation as also observed earlier.[9] Amblyopia seen more frequently in the LE (P < 0.0001) can be explained by ocular dominance of the RE, as has been reported in earlier studies.[22],[23] More frequent occurrence of amblyogenic factors in the LE could also be responsible for this observation.

Patients with anisometropic amblyopia are frequently unaware of it until adulthood when it is detected during a routine eye examination.[3] Amblyopia has been estimated to be responsible for 12.3% of severe visual impairment in India.[24],[25],[27] Severity and delayed presentation of amblyopia is a cause for concern. Increased awareness and earlier screening may help in timely management.

Limitations of our study are that it is retrospective and the possibility that our study population may not be representative of the community as we are a tertiary care referral center where usually the challenging cases are referred from other hospitals. Moreover, many amblyopes like those after pediatric cataract surgery are managed in our OPD itself. However, the subtypes that we have discussed are expected to be represented amongst the strabismus population. The mean age may not represent the usual age of presentation of the disease in paralytic deviations as they are known to have a bimodal distribution. We have tried to overcome this limitation by mentioning separately the number of infantile and later onset cases. We have also not reported the amount of deviation as we have noticed that the deviation is often variable, does not alter the diagnosis and except when very small does not change the management. Improvement with treatment has also not been discussed as it has too many variables considering the diversity of patients being managed. This study has provided clinical and demographic data related to strabismus and amblyopia for reference. The findings of lesser frequency of accommodative ET, 60% intermittency in XT, and only 15% prevalence of amblyopia in strabismus, indicate betterment of primary and secondary level healthcare in India.[3],[21] However, 70% not needing surgery and delayed presentation of patients suggests that there still remains scope for significant improvements.

  Conclusions Top

In our study, male to female ratio was 1.37, and the mean age of presentation of patients was about 18 years. Comitant strabismus was commoner than incomitant. The frequency of comitant ET and XT was almost equal. Sixth nerve palsy was the most common cause of incomitant strabismus. Amblyopia was more frequent and severe with comitant ET. LE and anisohypermetropia were more often associated with amblyopia. Densest amblyopia was seen with stimulus deprivation.

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There are no conflicts of interest.

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  [Table 1], [Table 2], [Table 3]


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