A global approach to describe retinal defocus patterns

Abstract

The popularity of myopia treatments based on the peripheral defocus theory has risen. So far, little evidence has emerged around the questions which of these treatments are effective and why. In order to establish a framework that enables clinicians and researchers to acknowledge the possible interactions of different defocus patterns across the retina, different peripheral refractive errors (PRX) of subjects and different designs of optical treatments were evaluated. Dioptric defocus patterns on the retinal level have been obtained by merging the matrices of dioptric defocus maps of the visual field of different scenarios with individual peripheral refractive errors and different optical designs of multifocal contact lenses. The newly obtained matrices were statistically compared using a non-parametric test with familywise error algorithms and multi-comparison tests. Results show that asymmetric peripheral refractive error profiles (temporal or nasal positively skewed) appear to be less prone to be changed by the defocus imposition of multifocal contact lenses than those presenting symmetric patterns (relative peripheral myopia or hyperopia).

Peripheral Defocus and Myopia Management: A Mini-Review

“…It concluded that asymmetric profiles seemed to be influenced less by defocus multifocal contact lenses than those with symmetric profiles, especially when skewed temporally or nasally [ 40 – 42 ]. This concurs with a study that presented that patients with asymmetric peripheral refraction were less prone to myopia progression, suggesting they may also be less receptive to changes that induce myopia, such as peripheral defocus [ 40 , 41 ].…”

2-D Peripheral image quality metrics with different types of multifocal contact lenses

“…As one theory supports the influence of the peripheral refractive error of the eye, the current study obtained similar results as reported earlier 32,33 . Looking beyond peripheral refraction, a global approach describing the retinal defocus patterns 34 can explain the inter-subject variability regarding the efficacy of myopia interventions 2 . While the question remains, as to how the retina distinguishes lower order as well as higher order aberrations, a more in-depth analysis of the full image quality is required.…”

“…Namely, the positive nasal skew (PNS) and the relative peripheral myopia (RPM) full inferior visual field presented a similar behaviour. Contrarily to the pure defocus analysis 34 , the deterioration of the image quality when contact lenses are worn, does not seem to rely on the skewness of the peripheral refraction. Only PTS (positive temporal skew) appears to overtake the optical treatments and be less receptive to changes produced by multifocal centre-distance lenses.…”

“…Earlier acquired data from thirteen subjects were retrospectively analysed 34 . On average, the subjects had a spherical equivalent error (SE) of −3.25 Dioptres (−0.75 to −6.50 Dioptres) and an axial length of 25.37 mm (22.55 to 26.50 mm).…”

“…The central refractive power was −0.25 dioptres for the distance focus and an additional power of +2.25 and +2.50 dioptres for the near-centre and distance-centre designs respectively. Further information regarding these contact lenses can be found here 34 .…”