Purpose : Since peripheral refraction is different in myopes and emmetropes, it has been suggested as a possible precursor for myopia development. While several studies already showed a genetic impact in central myopia, there are no studies on inheritance of peripheral refraction. To better understand this issue, we compared the peripheral refraction profiles between monozygotic (MZ) and dizygotic (DZ) twins.
Methods : 35 MZ twins (age:21.7±2.4 years) and 38 DZ twins (age: 21.3±2.5 years) were included in this study. Central refraction was measured using the Visual Adaptive Optics visual simulator (VAO; Voptica SL, Murcia, Spain). Peripheral refraction was evaluated using an open-view peripheral wave-front sensor (Voptica SL, Murcia, Spain). Three horizontal scans (±35°) were obtained in each eye for central and ±20° vertical fixations. We compared the spherical equivalent (SE) at the line of sight (LOS; 1 data point), central area (Central: ranging from 11° nasal up to 20° temporal; 32 data points), and rest of peripheral areas (Peripheral: included central beyond 20° and both superior & inferior scans; 172 data points). Differences between siblings were obtained from one randomly selected eye.
Results : Similar average LOS, Central and Peripheral SE were found for MZ (–2.0±1.8D, –2.2±1.7D and –2.6±1.4D), and DZ (–2.2±2.2D, –2.3±2.1D and –2.7±1.8D) twin groups. But average difference in SE between DZ siblings were above 0.7 D (p<0.01) at the three considered zones. Intraclass correlations of SE at the LOS, Central and Peripheral areas were higher in MZ (>0.85) than in DZ (<0.7) group.
Conclusions : Despite individual variability and having similar average SE throughout the retina, the MZ siblings showed a more similar overall refraction than DZ couples. Higher correlation between MZ at the three retinal areas considered; indicates the variance in SE was likely driven by a combination of genetic and shared environmental factors.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 – May 3, 2018.