The prevalence of myopia in children and juveniles has increased significantly in Korea and worldwide; in particular, the rates of myopia and high myopia in East Asia have grown rapidly. Myopia is easily corrected with spectacles or contact lenses. However, as children grow and mature, myopia can progress irreversibly and lead to vision-threatening complications. Thus, the prevention of myopia progression is an essential treatment goal. Many treatment strategies are being employed, including atropine eyedrops, specialized glasses, and orthokeratology (Ortho-K) lenses. Ortho-K is an effective treatment in managing myopia progression by lowering the rate of increase in refractive error and axial length. In this article, we review Ortho-K as a treatment for myopia progression, its history, mechanism, treatment regimen, and safety profile.

PURPOSE: We explored changes in photoreceptor function and histology in an iodoacetic acid (IAA)-induced model of feline retinal degeneration. METHODS: From January to October 2014, we studied 11 adult felines (22 eyes) over 2 years of age divided into two groups (two in a control and nine in an IAA group). The mean body weights of these two groups were 1.75 ± 0.35 and 1.61 ± 0.19 kg, and the male:female sex ratios 1:1 and 2:7, respectively. Electroretinograms (ERGs) were obtained before injection and at 1–4 week post-injection (20 mg/kg IAA). Standard paraffin retinal sections were stained with hematoxylin/eosin and other sections subjected to immunohistochemistry. We histologically evaluated the outer nuclear layer, and photoreceptor cone and rod cells. RESULTS: In ERGs of the IAA group, both the rod and cone mean b wave amplitudes decreased significantly from week 1 to week 4 after injection (27.43, 29.41, 64.17, and 56.03; and 61.04, 51.25, 131.36, and 136.68 µV, respectively) compared to baseline (322.48 and 610.00 µV respectively) (p < 0.01). Optical microscopy revealed a significant decrease in the cell count of the outer nuclear retinal layer (16.83 ± 0.89 in the control and 11.98 ± 3.55 in the IAA groups, p < 0.01). Fluorescence microscopy revealed a significant reduction in the mean area per unit length of the rod cell layer (35,225.67 ± 2,477.02 and 14,903.62 ± 2,319.65 in the control and IAA groups, p < 0.01), but not in the cone cell count (26.16 ± 1.34 and 23.98 ± 6.16 in the control and IAA groups, p = 0.075). CONCLUSIONS ERGs revealed that functional b wave amplitudes fell after IAA-induce retinal degeneration in felines; histology showed that this was accompanied by reductions in the numbers of outer nuclear layers and rod cells. IAA induces photoreceptor degeneration in felines; further study is necessary.