Frequency and associated factors of accommodative and non-strabismic binocular vision dysfunctions among clinical adults in Western China: A cross-sectional study.

This study aims to determine the prevalence and identify associated risk factors of accommodative and non-strabismus binocular vision dysfunctions among clinical adults aged 30 to 44 years in Western China. Consecutive eligible outpatients who visited the optometry clinic at the First Affiliated Hospital of Xinjiang Medical University were recruited. Comprehensive assessments of accommodative and binocular vision were conducted, including subjective and objective refractive status examination, Worth 4 dot test, distant and near horizontal eye position (Von Graefe method), positive fusional vergence (distance and near), negative fusional vergence (distance and near), near point of convergence (NPC), accommodative response (BCC, binocular cross-cylinder test), negative relative accommodation (NRA), positive relative accommodation, monocular accommodation amplitude (MAA; negative lenses), monocular accommodative facility (MAF; ±2.00 D flip mirror), and vergence facility (VF; 3ΔBI/12ΔBO). Prior to the start of the above examinations, a questionnaire survey was conducted using the convergence insufficiency symptom survey (CISS) designed by convergence insufficiency treatment trial (CITT). The results indicated that 64.83% of participants exhibited accommodative and non-strabismic binocular vision dysfunctions, of which 42.07% were classified as accommodative dysfunction and 37.25% as binocular anomalies. Among these dysfunctions, accommodative insufficiency was the most prevalent, accounting for 37.25%, followed by convergence insufficiency (CI) at 24.83% and convergence excess at 6.21%. A significant linear correlation was observed between the spherical equivalent (SE) of the right eye and parameters including convergence function, MAA, MAF, and positive fusion images at far range. Additionally, the CISS score was found to be significantly associated with the distance horizontal strabismic, stereopsis, NPC, MAA and MAF. Furthermore, the hours of near vision tasks were correlated with the distant positive and negative fusion ability, NPC and MAA. Multinomial logistic regression was conducted to identify potential risk factors associated with accommodative and non-strabismic binocular vision dysfunction. The results showed that hours of doing near vision tasks ≥ 6 hours and binocular SE difference ≥ 1.5 D were relevant factors for the frequency of accommodative and non-strabismic binocular vision abnormalities. Approximately two-thirds of the optometric clinical population in Western China - including individuals in the pre-presbyopic stage - may be affected by accommodative or non-strabismic binocular vision dysfunctions, potentially linked to prolonged near vision tasks.