Familial aggregation of hyperopia in an elderly population of siblings in Salisbury, Maryland

Abstract

Purpose-To determine whether hyperopia aggregates in families in an older mixed-race population.Design-Cross-sectional familial aggregation study using sibships.Methods-We recruited 759 subjects (mean age, 73.4 years) in 241 families through the population-based Salisbury Eye Evaluation study. Subjects underwent noncycloplegic refraction if best-corrected visual acuity (BCVA) was ≤20/40, had lensometry to measure their currently worn spectacles if BCVA was >20/40 with spectacles, or were considered to be plano (refraction of zero) if the BCVA was >20/40 without spectacles. Preoperative refraction from medical records was used for bilaterally pseudophakic subjects.Results-Utilizing hyperopia cutoffs from 1.00 to 2.50 diopters, age-, race-, and gender-adjusted odds ratios for hyperopia with an affected sibling ranged from 2.72 (95% confidence interval [CI], 1.84-4.01) to 4.87 (95% CI, 2.54-9.30). The odds of hyperopia increased with age until 75 years, after which they remained relatively constant. Black men were significantly less likely to be hyperopic than white men, white women, or black women.Conclusions-Hyperopia appears to be under strong genetic control in this older population.Hyeropia, or farsightedness, describes the refractive state where the focal point of light entering the eye is behind the retina, due to a short axial length relative to the eye's optical system. Hyperopia of >3.0 diopters (D) is estimated to affect 11.8 million persons over the age of 40 years in the United States, or 9.9% of the U.S. population. 1 Though the process of accommodation allows a number of these individuals to see normally without refractive correction, many others require spectacle, contact lens, or surgical correction, with the attendant risk of bacterial keratitis 2 or infection due to surgical correction of refractive error. [3][4][5] Additionally, children with high levels of hyperopia are at risk for accommodative esotropia, a condition that, if untreated, may result in amblyopia, impaired stereoscopic vision, and a significant reduction in vision-related functional status. 6 Although the number of children with accommodative esotropia is not well known, strabismus has been estimated to affect between 0.5% and 4% of children. [7][8][9][10] Esodeviations comprise >50% of this, 11 with refractive accommodative esotropia clearly playing a significant role. Evidence exists suggesting that hyperopia may be under strong genetic control. 14,15 Twin studies in England have suggested that hyperopia, treated as a binary trait, has a heritability of 89%, virtually the same as myopia. 14 Biometric traits such as axial length and radius of corneal curvature, which determine hyperopia, also demonstrated heritability in the 80% to 90% range in the British twin study. However, genetic studies of hyperopia have been far fewer than for myopia. A small number of genetic conditions have been identified that are characterized by hyperopia in conjunction with ocular 16 or systemic 17 abnormalities. To the best of our knowledge...

Age-related changes in the human visual system and prevalence of refractive conditions in patients attending an eye clinic

“…In the present study, there was a trend toward adults older than 40 years being less myopic than younger adults and adolescents. In older groups, there was also a trend toward a decrease in myopia, which agrees with results of Wojciechowski et al, 29 who found a higher prevalence of hyperopia in adults until 75 years of age. The hyperopic shift from the 30s, with a maximum mean hyperopic value in the elderly, also agrees with previous 2000 results of Montés-Micó and Ferrer-Blasco 18 for a much larger population in the same region of Spain.…”

Nature and nurture: the complex genetics of myopia and refractive error

“…More extreme refractive errors show even greater familial aggregation than do milder forms (107, 109). Moreover, children of myopic parents tend to have longer eyes (110) and are more likely to develop myopia during childhood or adolescence (111–113).…”

Gene profiling in experimental models of eye growth: Clues to myopia pathogenesis

“…So far, it is unclear whether myopia develops from adaptive physiologic responses to visual demands of modern societies or instead develops from physiologically inappropriate processes that may override, rather than exploit, normal regulatory mechanisms (Stone, 2008). Genetic factors have been implicated in the etiology of both myopia and hyperopia (Wojciechowski, Cogdon, Bowie, Munoz, Gilbert & West, 2005). Twin and family studies have long suggested a genetic component in myopia and several chromosomal loci have been linked with human myopia, including high myopia (Hornbeak & Young, 2009, Young, Metlapally & Shay, 2007).…”