Increased hyperopia with ageing based on cycloplegic refractions in adults: the Tehran Eye Study

Abstract

Although an age-cohort effect cannot be ruled out, these results provide the first population-based evidence of increasing hyperopia with age using cycloplegic refraction. The results obtained suggest that the contribution of decreasing accommodation to observed hyperopic shifts in distance refraction in longitudinal studies is small, raising the question of the underlying causes of the hyperopic shift in refraction with age.

High Prevalence of Myopia in an Adult Population, Shahroud, Iran

“…This finding was reported in the Tehran Eye Study and discussed by Hemenger et al as well and may be attributed to structural changes of the crystalline lens that occur with aging. 46,47 At higher levels of education, we found an increase in myopia and decrease in hyperopia. According to studies in China, 30 Singapore, 8 and Japan, 22 myopia increased with education, but the reverse was reported in studies in Bangladesh 4 and Myanmar.…”

Lens Power in a Population-Based Cross-Sectional Sample of Adults Aged 40 to 64 Years in the Shahroud Eye Study

“…10 This loss slows markedly and progressively to reach a minimal but nevertheless significant rate of loss after the age of 10 to 12, [11][12][13] and this loss in lens power appears to continue after this age for most of adult life. 14 Over this period, while the lens slowly loses power, the lens thickens and its curvatures steepen, which should lead to increased power-a phenomenon that has come to be known as the lens paradox. 15 The observed loss of lens power appears to be due to changes in the gradient index of the lens, 16 which emphasizes that lens thickness does not provide a surrogate measure of lens power.…”

“…[20][21][22] Early in development, loss of lens power appears to limit the effects of axial growth by balancing the myopic shifts associated with axial elongation against the hyperopic shifts Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc. www.iovs.org j ISSN: 1552-5783 associated with loss of lens power; but later in adult life, when axial elongation is minimal or has stopped, the slow loss of lens power appears to lead to hyperopic shifts in refraction. 14,23 The Shahroud Eye Cohort Study is a large, population-based study of adults aged 40 to 64 years at baseline (2009)(2010) in Shahroud, a provincial city with a population of over 100,000 in northeastern Iran. It has several strengths, including a large sample size (over 5000); a participation rate of 82.2%; the systematic use of cycloplegia, which is important for the accurate estimation of spherical equivalent refraction and the subsequent calculation of lens power; systematic collection of sociodemographic information; and planned follow-up after 5 years.…”

Crystalline Lens Power and Refractive Error

“…In adulthood, a hyperopic shift in the ocular refractive error occurs, probably due to a reduction in crystalline lens refractive power. 6 Later in life, when cataract develops, a myopic shift in ocular refractive error is found, potentially due to an increase in the crystalline lens refractive power. Although these changes in crystalline lens power throughout life have an impact on the refractive status of the eye, they have not been thoroughly studied yet, because of the difficulty in measuring the crystalline lens refractive power.…”