Abstract
Mechanical tissue stresses are important contributors to the increased risk of sight-threatening pathology in larger, more myopic eyes. The contribution of altered ocular vasculature to the development of this pathology is less well defined. The current study investigated the impact of eye size on the superficial vasculature of the macula. Subjects (n = 104) aged 18–50, with no history of ocular or vascular disease, or myopia control, were recruited from university staff and student populations in Australia and Hong Kong. Refractive error, ocular size, retinal morphology and vascular morphology were quantified through open field autorefraction, ocular biometry and ocular coherence tomography angiography. Morphology of the superficial retinal capillary plexus was assessed over a 3 × 3 mm fovea-centred area. Perfusion area and vessel length densities were analysed relative to axial eye length and retinal thickness. A significant inverse association was found between axial length and vascular density measures (perfusion area density r2 = 0.186, p < 0.001; and vessel length density r2 = 0.102, p = 0.001). Perfusion area and vessel length densities were reduced by 5.8% (p = 0.001) in the longest, relative to the shortest, eyes. The aggregated ganglion cell layer inner plexiform layer thickness was also inversely associated with eye size (r2 = 0.083, p = 0.003), and reduced, by 8.1% (p < 0.001), in the longest eyes. An inverse association of eye size and superficial retinal vasculature density, that is not simply explained by retinal expansion or image magnification factors, was confirmed. These data support the hypothesis that ongoing metabolic challenges may underlie the development of myopia-related and -associated pathology in larger eyes.
Highlights
Myopia was present in 28.3% of the population in 2010 and this is expected to rise to 52% by 2050 [1]
Perfusion area density was defined as the percentage of total area of perfused vasculature per unit area in a region of measurement, whereas vessel length density was defined in mm−1 as the total length of perfused vasculature per unit area in the region of measurement
The instrument used employed an axial length of 23.80 mm as the reference; no correction was made to measurements based on axial length as: (1) the 3 × 3 mm field employed is small enough to be relatively robust to magnification variations with eye size; and (2) the image magnification effect in larger eyes results in an increase in vascular density; the deficits we report here are, if anything, an underestimation of the true deficits in larger eyes [10]
Summary
Myopia was present in 28.3% of the population in 2010 and this is expected to rise to 52% by 2050 [1] This rapid increase in global myopia prevalence, coupled with the increasing availability of clinical interventions and protocols to slow the progression of myopia [2], warrants a greater understanding of both the earliest signs of myopia development and the pathophysiologic consequences of the condition. Such an understanding will help clinicians better identify those that may benefit from myopia control interventions, and combat the visual impairment associated with increasing degrees of myopia [1,3,4]. Retinal detachment and myopic maculopathy are just some of the pathological conditions that are known to result [6,7]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
