Diffusion Optics Technology (DOT): A Myopia Control Spectacle Lens Based on Contrast Theory

Abstract

Diffusion optics Technology (DOT) myopia control spectacle lenses are based on contrast theory. This innovative theory represents a radical departure from the classical concept of visual deprivation myopia. However, traditional theories have evolved, arriving at remarkably similar solutions for myopia control as the DOT lenses. Nonetheless, contrast theory still represents a departure from mainstream theories. Here, in an effort to resolve discrepancies, we review the science behind contrast theory and compare it to more conventional blur and defocus theories. Finally, we consider the implications of the different theories for the rational design of myopia control solutions.

Figure 1.

Each data point represents corneal curvature and axial length measurements from an emmetrope measured using a Zeiss IOLMaster (Zeiss, Oberkochen, Germany). There is enormous variability in the eye's optical power, primarily because of differences in corneal curvature. Eyes with more curved corneas have shorter focal lengths. There is a strong inverse correlation (R² = 0.7331) between the axial length and corneal curvature as a result of the eye using feedback from the qualities of the images on the retina to control axial growth. These subjects were drawn from a study done in our laboratory in which 373 participants 17 years and over (mean age = 36.3 ± 14.9 years, 45% female, 55% male) were recruited by advertisement through the Optometry and Ophthalmology practices at the Eye Institute of the Medical College of Wisconsin. All research on human subjects followed the tenets of the Declaration of Helsinki and was approved by the IRB at the Medical College of Wisconsin. Respondents with a history of ocular disease, except for refractive error, were excluded from the study. Subjects were divided into four categories: hyperopes (positive SER), emmetropes (no refractive error), low-to-moderate myopes (negative SER < −6 D), and pathological myopes (SER ≥ −6D). Only the emmetrope data is shown.

Figure 2.

Every L and M cone photoreceptor in the human eye across the entire retina has one ON and one OFF midget bipolar cell. Midget bipolar cells have spatially opponent, center-surround receptive fields, making them contrast detectors. A single cone makes up the center of the receptive field, and its neighbors make up the inhibitory surround mediated by horizontal cells. Normally, when both the center and surround are covered by uniform illumination, the mutually inhibitory center and surround cancel, and there is no response. (A) However, when more light from the retinal image falls on the center cone than the surround. The ON bipolar cell is activated–signaling light against a dark background contrast. For example, it could be signaling part of a white letter against a dark background. (B) When more light from the retinal image falls on the surrounding cones than the center cone, the OFF bipolar cell is activated, signaling dark against a light background contrast. For example, it could be signaling part of a black letter against a white background. (C) If the central cone expresses a normal gene but a submosaic of cones in the surround express the mutation which makes them inefficient at absorbing light, under uniform illumination with no contrast, the cone will absorb more photons than the average of its neighbors and the ON midget bipolar cells will respond, signaling high contrast even in the absence of a high-contrast stimulus. (D) Alternatively, If the central cone of a bipolar cell receptive field expresses the mutant gene and is inefficient at absorbing light under uniform illumination with no contrast, it will absorb fewer photons than the average of its neighbors, which are a mixture of normal and mutant cones, and the OFF midget bipolar cells will respond signaling high contrast even in the absence of contrast in the stimulus.