Myopia has been predicted to affect approximately 50% of the world's population based on trending myopia prevalence figures. Critical to minimizing the associated adverse visual consequences of complicating ocular pathologies are interventions to prevent or delay the onset of myopia, slow its progression, and to address the problem of mechanical instability of highly myopic eyes. Although treatment approaches are growing in number, evidence of treatment efficacy is variable. This article reviews research behind such interventions under four categories: optical, pharmacological, environmental (behavioral), and surgical. In summarizing the evidence of efficacy, results from randomized controlled trials have been given most weight, although such data are very limited for some treatments. The overall conclusion of this review is that there are multiple avenues for intervention worthy of exploration in all categories, although in the case of optical, pharmacological, and behavioral interventions for preventing or slowing progression of myopia, treatment efficacy at an individual level appears quite variable, with no one treatment being 100% effective in all patients. Further research is critical to understanding the factors underlying such variability and underlying mechanisms, to guide recommendations for combined treatments. There is also room for research into novel treatment options.
15 September 2019 in Annual Review of Vision Science
Refractive errors are the product of a mismatch between the axial length of the eye and its optical power, creating blurred vision. Uncorrected refractive errors are the second leading cause of worldwide blindness. One refractive error currently attracting significant scientific interest is myopia, mostly owing to the recent rise in its prevalence worldwide and associated ocular disease burden. This increase in myopia prevalence has also been rapid, suggesting environmental influences in addition to any genetic influences on eye growth. This review defines refractive errors, describes their prevalence, and presents evidence for the influence of genetic and environmental factors related to refractive error development.
The purpose of this study was to evaluate some of the methods used to calculate objective refractions from wavefront aberrations, to determine their applicability for accommodation research. A wavefront analyzer was used to measure the ocular aberrations of 13 emmetropes and 17 myopes at distance, and 4 near target vergences: 2, 3, 4, and 5 D. The accommodative response was calculated using the following techniques: least squares fitting (Zernike defocus), paraxial curvature matching (Seidel defocus), and 5 optical quality metrics (PFWc, PFSc, PFCc, NS, and VSMTF). We also evaluated a task-specific method of determining optimum focus that used a through-focus procedure to select the image that best optimized both contrast amplitude and gradient (CAG). Neither Zernike nor Seidel defocus appears to be the best method for determining the accommodative response from wavefront aberrations. When the eye has negative spherical aberration, Zernike defocus tends to underestimate, whereas Seidel defocus tends to overestimate the accommodative response. A better approach is to first determine the best image plane using a suitable optical quality metric and then calculate the accommodative error relative to this plane. Of the metrics evaluated, both NS and VSMTF were reasonable choices, with the CAG algorithm being a less preferred alternate.
In the following point‐counterpoint article, internationally‐acclaimed myopia researchers were challenged to defend the two opposing sides of the topic defined by the title; their contributions, which appear in the order, Point followed by Counterpoint, were peer‐reviewed by both the editorial team and an external reviewer. Independently of the invited authors, the named member of the editorial team provided an Introduction and Summary, both of which were reviewed by the other members of the editorial team. By their nature, views expressed in each section of the Point‐Counterpoint article are those of the author concerned and may not reflect the views of all of the authors.
2 April 2024 in Ophthalmic and Physiological Optics