Disparity between central and peripheral refraction inheritance in twins

Dibyendu Pusti,Antonio Benito,Juan R Ordoñana,Juan J Madrid-Valero,Pablo Artal

doi:10.1038/s41598-021-90838-8

Abstract

The last decades have witnessed a sudden increase in myopia incidence among youngsters that have been related to modern lifestyle along with the use of emerging technologies affecting visual exposure. Increasing exposures to known risk factors for myopia, such as time spent indoors, close-distance work, or low-light conditions are thought to be responsible for this public health issue. In most cases, development of myopia is secondary to a vitreous chamber enlargement, although the related mechanisms and the potential interaction between central and peripheral retinal area remain unclear. For a better understanding, we performed a classical twin study where objective refractive error along 70° of horizontal retinal arc was measured in 100 twin pairs of university students, 78% of which showed manifest myopia. We found the variance of shared environmental origin (range 0.34 to 0.67) explained most of the objective refractive error variance within central 42° of the retina (22° temporal to 19° nasal), whereas additive genetic variance (range 0.34 to 0.76) was predominant in the peripheral retinal areas measured. In this sample of millennial university students, with a large prevalence of myopia, environmental exposures were mostly responsible for inter-individual variation in the retinal horizontal area surrounding the macula, while their relative weight on phenotypic variance was gradually descending, and replaced by the variance of genetic origin, towards the retinal periphery.

Highlights

Of these studies were conducted either across a general population including all age groups or an old population
With the comprehensive Structural Equation Modelling (SEM) analyses, we found the highest total phenotypic variance concentrated around the central retina, which gradually decreased towards the periphery
The decreasing total phenotypic variance towards both sides of the peripheral retina coincided with increasing additive genetic variance (Fig. 2, left) accompanied by a gradual decrease in shared environmental variance (Fig. 2, center)

Summary

Introduction

Of these studies were conducted either across a general population including all age groups or an old population. This study included a wide age span, ranging from children to young adults (8–20 years), with very different levels of physical development and visual need or exposure, and it was limited in that they only studied PR at a single peripheral angle (40° from the fovea); neither did it provide information about the refractive error at the line of sight (central measurements) This approach, using a single point estimate, may not be useful for identifying trends or change patterns, it could miss relevant shifts in refraction across the retina, and it could be more susceptible to possible measurement errors than multi-point approaches, resulting, in general, in a less sensitive measure. The point-by-point refraction data gave us the power to obtain a detailed estimation of the genetic and environmental influences on PR across a large retinal area to offer information about the impact of environmental exposures on the mechanisms of eye development

Methods

Results

Conclusion