Environmental and Genetic Factors Explain Differences in Intraocular Scattering

Abstract

Citation: Benito A, Hervella L, Tabernero J, et al. Environmental and genetic factors explain differences in intraocular scattering. Invest Ophthalmol Vis Sci. 2016;57:163-168. DOI:10.1167/iovs.15-17897 PURPOSE. To study the relative impact of genetic and environmental factors on the variability of intraocular scattering within a classical twin study. METHODS.A total of 64 twin pairs, 32 monozygotic (MZ) (mean age: 54.9 6 6.3 years) and 32 dizygotic (DZ) (mean age: 56.4 6 7.0 years), were measured after a complete ophthalmologic exam had been performed to exclude all ocular pathologies that increase intraocular scatter as cataracts. Intraocular scattering was evaluated by using two different techniques based on a straylight parameter log(S) estimation: a compact optical instrument based in the principle of optical integration and a psychophysical measurement. Intraclass correlation coefficients (ICC) were used as descriptive statistics of twin resemblance, and genetic models were fitted to estimate heritability. RESULTS.No statistically significant difference was found for MZ and DZ groups for age (P ¼ 0.203), best-corrected visual acuity (P ¼ 0.626), cataract gradation (P ¼ 0.701), sex (P ¼ 0.941), optical log(S) (P ¼ 0.386), or psychophysical log(S) (P ¼ 0.568), with only a minor difference in equivalent sphere (P ¼ 0.008). Intraclass correlation coefficients between siblings were similar for scatter parameters: 0.676 in MZ and 0.471 in DZ twins for optical log(S); 0.533 in MZ twins and 0.475 in DZ twins for psychophysical log(S). For equivalent sphere, ICCs were 0.767 in MZ and 0.228 in DZ twins. Conservative estimates of heritability for the measured scattering parameters were 0.39 and 0.20, respectively. CONCLUSIONS.Correlations of intraocular scatter (straylight) parameters in the groups of identical and nonidentical twins were similar. Heritability estimates were of limited magnitude, suggesting that genetic and environmental factors determine the variance of ocular straylight in healthy middle-aged adults.

Micrometric Control of the Optics of the Human Eye: Environment or Genes?

“…Additionally, intraocular scatter, which also has a clear influence in vision, has been recently investigated using a similar twinstudy, showing less genetic effects and more environmental influence in the variance of the phenotype. 38 Those results complement our study, which offers novel information about the normal (nonpathological) level of aberrations.…”

Inheritance of Refractive Error in Millennials

“…We found a high prevalence of low and moderate myopia in a sample of young twins (average year of birth was 1995.8 ± 3.0). A previous similar study was performed in a sample of twins born in the same geographical area, with an average age at the moment of the measurements (2014) of 54.9 ± 6.3 years (average year of birth was 1958.3 ± 6.7) 34,40 . On average, their manifest refraction gave a SE that was emmetropic (0.0 ± 1.4 D) for the MZ twins, and slightly hyperopic (+0.5 ± 1.6 D) for the DZ twins.…”

“…Many studies showed an increasing trend of myopia incidence as www.nature.com/scientificreports www.nature.com/scientificreports/ we are approaching the era of modern industrialization along with increasing education level 3,11,19,20 . The older twin sample 34 had in average a lower education level and possibly less prolonged near task. This may signify the connection of these trends with our obtained results with greater environmental influence on refractive error variance among studied millennials.…”

“…Studies also showed that, regardless of these environmental influences, myopia still maintains a substantial genetic influence with higher odds ratio with parental myopia 32,33 . In this context, previous studies on heritability of refractive error showed a strong genetic impact [34][35][36][37][38][39] . The heritability for myopia has not been examined in a context of an intensified myopigenic environment.…”

The diversity of leaves and asiaticoside content on three accessions of Centella asiatica with the addition of chicken manure fertilizer

“…The differences in morphology are also shown from the results of research by Bernawie (2013), which states that there are differences in the characteristics and size of C. asiatica morphology that grow in different environments. Morphological differences influenced by genetic factors, environmental factors, and the interaction of both (Benito et al 2016).…”