TNOA Journal of Ophthalmic Science and Research

: 2017  |  Volume : 55  |  Issue : 3  |  Page : 182--186

Clinical profile of nonstrabismic binocular vision anomalies in patients with asthenopia in North-East India

Damaris Magdalene, Pritam Dutta, Mitalee Choudhury, Saurabh Deshmukh, Krati Gupta 
 Department of Pediatric Ophthalmology and Strabismus Services, Sri Sankaradeva Nethralaya, Guwahati, Assam, India

Correspondence Address:
Dr. Saurabh Deshmukh
Sri Sankaradeva Nethralaya, 96, Basistha Road, Beltola, Guwahati - 781 028, Assam


Aim: To report the clinical profile of non-strabismic binocular vision anomalies (NSBVA) in patients with asthenopia in North-East India. Materials and methods: A hospital based study was conducted on 131 patients from age group 10-40 years attending the vision therapy clinic. Patients were divided into the age groups 10-20 years, 21-30 years and 31-40 years. A detailed orthoptic evaluation was carried out including sensory and motor testing and a diagnosis was made comparing various orthoptic parameters of the particular patients. Results: Of the 131 patients, 81 were female and 50 were male. The number of patients was 62 in the 10-20 years age group, 49 in 21-30 years age group and 20 in 31-40 years age group. The prevalence of NSBVA in age group 10-20 years was 69.35%, 21-30 years was 67.35% and 31-40 years was 50.00%. It was observed that the most common NSBVA was convergence insufficiency across all age groups followed by accommodative insufficiency and convergence excess. Conclusion: Early detection of NSBVA is important because these deviations may decompensate without treatment and become strabismic resulting in loss of stereopsis and development of suppression. Early detection and treatment provides best opportunity for academic success in school going age groups.

How to cite this article:
Magdalene D, Dutta P, Choudhury M, Deshmukh S, Gupta K. Clinical profile of nonstrabismic binocular vision anomalies in patients with asthenopia in North-East India.TNOA J Ophthalmic Sci Res 2017;55:182-186

How to cite this URL:
Magdalene D, Dutta P, Choudhury M, Deshmukh S, Gupta K. Clinical profile of nonstrabismic binocular vision anomalies in patients with asthenopia in North-East India. TNOA J Ophthalmic Sci Res [serial online] 2017 [cited 2020 May 31 ];55:182-186
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Full Text


Accommodative and binocular vision disorders are the second most common visual disorders in the clinical pediatric population only next to the refractive anomalies.[1] These dysfunctions are clubbed under a broad heading of “nonstrabismic binocular vision anomalies” (NSBVA). NSBVA mostly affects the binocularity, clarity and impair the comfort, visual performance, and efficiency of patients particularly with difficulty in near vision.[2]

The fundamental part of a child's education involves learning through reading. Reading involves both accommodative and vergence mechanism and an imbalance between the sensory-motor integrative functions results in nonstrabismic accommodative and/or binocular vision anomalies. Therefore, any abnormality in the visual system will affect children's cognitive development and educational progress. NSBVA mostly affects school-age children and especially high school learners who have an increased demand for the use of accommodative and vergence system. Symptoms of eye strain, eye ache, fatigue, and discomfort are further aggravated by prolonged near tasks thereby affecting the overall quality of life.[3]

With an increase in the use of computer and cell phones, the near and intermediate visual tasks have increased dramatically, and so a large percentage of individuals are found to have binocular vision problems and ocular discomfort.[3]

Therefore, the present study aims to find the prevalence of NSBVA with asthenopia in various age groups of patients attending vision therapy clinic at a tertiary eye care center and to find out the clinical diagnosis using various orthoptic parameters. Moreover, no such study has been conducted in the North-East Indian population to address these conditions and this study shall help better prepare health-care service providers to understand the needs of their patients.

 Materials and Methods

A prospective, hospital-based, interventional study was conducted at a tertiary eye care center on 131 patients from January 2017 to July 2017 after approval by Institutional Review Board. All consenting patients between the age group 10–40 years, presenting with complaints of asthenopia were included in the study. Patient with binocular vision anomalies secondary to strabismus, amblyopia, anisometropia (more than 2.00 Diopters), ocular pathology, ocular surgery, and neurological deficits was excluded from the study. A written consent form was obtained from each patient before the enrolment in the study.

The patients first presented to the general ophthalmology department and a complete ophthalmic evaluation of the patient including visual acuity, refraction, slit lamp examination, detailed assessment of anterior and posterior segment was done and if the asthenopic symptoms were present, patients were called for postmydriatic test and orthoptic evaluation after 3 days. In orthoptic clinic, the onset, duration and progress of presenting complaints was recorded. History of difficulty in vision for distance and near, eye strain, pain, discomfort, intermittent blurring for distance and near, diplopia, asthenopia, and headache was recorded. Stereopsis was checked using Titmus fly test. With patient's required glass prescription in place, an appropriate Monocular Estimate Method card was selected and with the help of retinoscope a sweep was made and the amount of “with” or “against” motion for each meridian was estimated and interposed with lenses. Then, Maddox rod was placed in front of the right eye with the striations oriented horizontally and a penlight torch was held at 3 m, and the patient was asked whether the red line is to the right or left of the spotlight and accordingly prisms were placed. After complete measurement of phoria, accommodative convergence/accommodation ratio was calculated using heterophoria method. For measuring near the point of convergence (NPC) and near point of accommodation (NPA) the royal air force rule was used. For negative relative accommodation plus lenses and for positive relative accommodation minus lenses were added until the patient reported first sustained blur. Fusional vergence measurement was done with the help of prism bar and accommodative target for distance and near. Base-out prism used for assessment of positive fusional vergence (PFV) and Base-in prism for negative fusional vergence (NFV). Prism bar was placed in front of one eye and power was gradually increased till the target became a blur (Blur), double (Break), and then the power of prism was decreased till the patient reported the target single again (Recovery). All three values were noted down distance and near. Accommodative facility measurement was done using ± 1.00DS, ± 1.50DS, and ± 2.00 DS Flippers. The patient was asked to call out the word after each flip and continue this for 1 min and cycles per minute were calculated by the number of flips.

All data were entered into a Microsoft Excel database (Microsoft, version 2015). Analyses were conducted, followed by frequencies, percentage, and correlation using SPSS (version 21.0 for Windows; SPSS Inc., Chicago, IL, USA).

The findings of each patient were analyzed, and the diagnosis was made on the basis of flowchart given below [Figure 1].[4]{Figure 1}


A total of 131 patients were evaluated after selection on the basis of selection criteria. The mean age was 21.71 ± 7.85 years. The number of patients was 62 in the 10–20 years of age group, 49 in 21–30 years of age group, and 20 in 31–40 years of age group.

Of the 131 patients, 81 were female and 50 were male. There were 69.35% female patients and 30.65% male patients in 10–20-year group, 53.06% female patients and 46.94% male patients in 21–30-year group and 60% female patients and 40% male patients in 31–40-year group of patients.

The prevalence of NSBVA in the age group 10–20 years was 69.35%, 21–30 years was 67.35%, and 31–40 years was 50.00% [Table 1].{Table 1}

It was observed that the most common NSBVA was convergence insufficiency (CI) across all age groups followed by accommodative insufficiency (AI) and convergence excess (CE). In 10–20 years of age group, the most common NSBVA was CI followed by accommodative infacility (A. Inf). Similarly, in 21–30 years of age group, the most prevalent NSBVA was CI followed by AI and in 31–40 years of age group, it was CI followed by CE [Table 2].{Table 2}


This is the first prospective hospital-based study using a complete binocular vision and orthoptic evaluation to find out the prevalence of nonstrabismic binocular vision disorder with asthenopia in patients of pediatric and nonpediatric age groups presenting to a tertiary eye care center in North-East India.

Age and sex distribution

The age group included in this study ranges from 10 to 40 years. In the present study, the percentage of females was higher than that of males. Out of 131 patients, there were 61.83% (n = 81) female and 38.17% (n = 50) male patients. A similar study conducted by Rao [5] reported male ratio to be higher than the females, where out of 182 patients, 64 were female and 118 were male. The study population was subdivided into three age groups, i.e., 10–20 years, 21–30 years, and 31–40 years owing to different forms of working pattern in these age groups. In the age group 10–20 years, out of 62 patients 69.35% (n = 43) were female and 30.65% (n = 19) were male. In the age group 21–30 years, of 49 patients, 53.06% (n = 26) were female and 46.94% (n = 23) were male. Similarly, in the age group 31–40 years, of 20 patients, 60% (n = 12) were female and 40% (n = 8) were male. There are only a few other studies which determined the sex distribution among NSBVA. Most of the previous studies were conducted in pediatric age group and only one study shows the similarity in age groups enrolled.[5],[6],[7],[8],[9],[10]. Besides this, the differentiation of the patients according to their age is important when considering prevalence values. It must be taken into account that responses of young children to several tests may not be as reliable as those of the adults.

Prevalence of nonstrabismic binocular vision anomalies

A number of accommodative and vergence anomalies are confronted in clinical care, and a number of classification systems are available to help categorize these disorders. The most common is Duane's [11] classification which was later extended to NSBVA by Tait.[12] Moreover, a normative data analysis of the NSBVA was made by Scheimann and Wick [4] in 1944 which had an advantage of flexibility and ease of use compared to the complexity and rigidity associated with graphical and analytical analyses. In our study, 67.35% (n = 87) of the patients had NSBVA, 22.45% (n = 28) were emmetropes and 10.20% (n = 16) had refractive errors only. The previous study conducted by Rao [5] also found 142 out of 182 patients to have NSBVA.

The prevalence of CI in 10–20 years of age group was 37.10%, in 21–30 years of age group was 38.77%, and in 31–40 years of age group was 20.00%. Hence, CI was found to be the most common NSBVA in all age groups which is in line with the results of the study conducted by Rouse et al.[13] Similarly, Letourneau and Ducic [14] and Hoseini-Yazdi et al.[15] found the prevalence to be 8.3% and 19.3%, respectively. Although the numbers vary considerably between studies, it is important to note that CI accounts for a significant percentage of NSBVA in pediatric population. However, in this study, CI was found to be highly prevalent in nonpediatric age group too.

AI was also found to have the highest prevalence in some studies. García et al.[16] in their study aimed at evaluating the relative accommodations in general binocular dysfunctions and found that 45% of the population studied had accommodative dysfunction. Paniccia [7] conducted a study in Puerto Rico, using a random selection of 593 existing health records of patients between the ages of 5–20 years and found the prevalence of AI (39%) to be more than rest of the nonstrabismic binocular vision disorders. In contrast to the previous studies, the AI percentage in our study was 8.06% in 10–20 years of age group, 10.20% in 21–30 years of age group and 10.00% in 31–40 years of age group, which is comparatively less.

Moreover, in this study, the prevalence of CE was found to be 15% in 31–40 years of age group. Lara et al.[17] who found CE (4.5%) to be more prevalent than CI (0.8%) in a nonpediatric population. Hokoda [18] found a prevalence rate of 5.9% CE in a population of symptomatic individuals seeking vision care. Similarly, Scheiman et al.[1] found a higher prevalence of CE (8.2%) than CI.

Furthermore, the results of this study show a prevalence of 37.10% CI and 8.06% (n = 4) AI in 10–20 years of age group. These outcomes are important as numerous studies have correlated AI and CI as factors affecting the academic performance of school-age children.[8],[19]

In contrast to the study conducted by Paniccia [7] and Lara et al.[17] [Table 3]. Our study shows differences in the prevalence rate of the dysfunctions. This may be due to different diagnostic criteria used in different studies or may be due to the difference in the targets used. Some authors diagnosed CI simply on the basis of low NPC values with accommodative target while some used different orthoptic parameters correlating with convergence to attain the final diagnosis. The higher prevalence rate in 10–20 years of age group in our study may be due to the symptoms which tend to occur when persons use their eyes in a two-dimensional reading environment for extended periods of time which tend to increase during teenage years and continue to increase during their early twenties.{Table 3}

Limitations of our study are small sample size and shorter duration of the study. The efficacy and outcomes of vision therapy in NSBVA patient could not be demonstrated because of the short duration of the study.


To conclude, efforts should be made for early detection of NSBVA as some of these deviations may decompensate without treatment and become strabismic resulting in loss of stereopsis and development of suppression. Early detection and treatment provide the best opportunity for academic success in school going age group.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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