Journal of Ophthalmic and Vision Research

Published date: Jul 18 2019

Journal Title: Journal of Ophthalmic and Vision Research

Issue title: July–September 2019, Volume 14, Issue 3

Pages: 306 - 314

DOI: 10.18502/jovr.v14i3.4787

Hassan HashemiNoor Research Center for Ophthalmic Epidemiology, Noor Eye Hospital, Tehran, Iran; Noor Ophthalmology Research Center, Noor Eye Hospital, Tehran, Iran

Mojgan PakbinNoor Research Center for Ophthalmic Epidemiology, Noor Eye Hospital, Tehran, Iran; Research and Technology Deputy, Tehran University of Medical Sciences, Tehran, Iran

Babak AliDepartment of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran

Abbasali YektaYektaa@mums.ac.irDepartment of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran

Hadi OstadimoghaddamRefractive Errors Research Center, Mashhad University of Medical Sciences, Mashhad, Iran

Amir AsharlousNoor Research Center for Ophthalmic Epidemiology, Noor Eye Hospital, Tehran, Iran

Mohammadreza AghamirsalimEye Research Center, Tehran University of Medical Sciences, Tehran, Iran

Mehdi KhabazkhoobDepartment of Medical Surgical Nursing, School of Nursing and Midwifery, Shahid Beheshti University of Medical Sciences, Tehran, Iran

Purpose: To determine the distribution of the near point of convergence (NPC) and near point of accommodation (NPA) in a young student population in Iran.

Methods: The subjects were selected using a cluster sampling method. All students underwent optometry tests, including visual acuity measurement, refraction, and cover test, as well as ophthalmic examinations. The NPC and NPA were measured using an accommodative target (near Snellen chart).

Results: Of 1,595 students, the data of 1,357 were analyzed. The mean NPC and NPA in the total sample were 7.25 cm (95% confidence interval [CI], 7.02 to 7.48) and 9.99 cm (95% CI, 9.69 to 10.29), respectively. Older age was associated with an increase in the NPC, which increased from 6.98 cm in 18–20 years olds to 9.51 cm in those over 30 years. The NPA was significantly associated with age and refractive errors in the multiple linear regression model, increasing from 9.92 cm in 18–20 years olds to 11.44 cm in those over 30 years (P = 0.003). Hyperopic eyes had lower NPA than myopic and emmetropic eyes (P = 0.001). In younger age groups, the mean accommodation amplitude was lower than the mean Hofstetter value. Moreover, with age, especially after 30 years, the mean values surpassed those determined using the Hofstetter formula.

Conclusion: The NPC values in this study were lower than those previously reported for identical age groups. The Hofstetter formula is not always an accurate predictor of the accommodation amplitude in the Iranian adult population.

Keywords: Cross-sectional Study; Distribution; Near Point of Accommodation; Near Point of Convergence

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