The relationship between binocular vision symptoms and near point of convergence.

Aim and Background: Due to the relatively high prevalence of binocular vision anomalies, a regular examination including tests for assessment and determination of these anomalies is necessary. The aim of this study was to assess the relationship between near point of convergence (NPC) and near binocular vision symptoms and finding of an NPC cutoff point for symptoms in university students. Materials and Methods: In this cross-sectional study, 124 students of different majors of Zahedan University of Medical Sciences were randomly selected. If they met the inclusion criteria, they were divided into two groups (symptomatic and asymptomatic) according to the convergence insufficiency symptom survey questionnaire. For NPC measurement, a small isolated letter E of approximately 20/30 size on a metal rod was used. After data collection, data were analyzed in SPSS.17 software (SPSS for Windows, SPSS Inc., Chicago, IL) using descriptive and analytical statistics, including Mann–Whitney U test and receiver operating characteristic (ROC) curve. Results: The mean NPC findings in the symptomatic and asymptomatic groups were 11.7 ± 5.0 and 8.4 ± 3.4 cm, respectively, with a significant difference between the two groups (P < 0.001). The ROC curve suggests an NPC cutoff point of 9.5 cm for the presence of symptoms with the testing procedures used in this study. Conclusion: The determination of NPC is helpful in the differentiation of symptomatic from asymptomatic subjects.

Body mass index and binocular vision skills

Body Mass Index [BMI] is of increasing interest to eye care practitioners. Associations have recently been proven between high BMI and several diseases affecting the eyes, including AMD, intracranial hypertension, optic disc cupping, and glaucoma. The symptoms of dizziness and vertigo have also been associated with high BMI. However, to these authors' knowledge, there has been no study performed comparing BMI to binocular function. In this analytical-descriptive study, 119 randomly selected young subjects had their BMI measured, along with refractive error, dissociated phoria, near point of convergence, vergence ranges and facility, and stereopsis. In most situations, the subjects classified as normal and overweight, based on their BMI had better performance than those classified as underweight or obese. The worst binocular performance was found in underweight subjects. The one-way ANOVA showed only statistically significant differences between mean of near point of convergence and vergence facility, in different states of BMI. Unlike most ocular diseases that are adversely affected by higher BMI values, most binocular vision skills are adversely affected by lower BMI values. The possible reasons for this are discussed