8/19/2023 0 Comments Normal pupil size mm![]() ![]() 12 This may be due to the impact the atropine has on dilating the pupils, enhancing the effect of the orthokeratology. A meta-analysis from 2020 looked at clinical records of 341 children and found 0.09mm less axial elongation, over a year, in children on dual treatment when compared to orthokeratology alone. The pupils may hold the key to why a combination therapy of atropine and orthokeratology work better together than either treatment used separately. Pupil size was measured, but any interaction between pupil size and myopia control was either not present or not reported in this research abstract. The latest data on treatment zone size in ortho-k has found that children wearing a 5mm BOZD lens exhibited only 0.15mm axial growth over two years, compared to 0.35mm in a 6mm BOZD group. One previous study demonstrated that children with a larger pupil sizes have better myopia control in ortho-k, 10 with a review suggesting those with larger pupils had 50% less axial length growth. Children with pupils that were larger than the topographical treatment zone had slower axial length growth than those whose pupil size fell within the treatment zone. As the pupil diameter increases, the increased retinal area exposed to myopic defocus may enhance the defocus effect of the ortho-k treatment.Ī 2021 study reported retrospective observations from an orthokeratology clinic, where the back optic zone diameter (BOZD) of the ortho-k lens was altered specific to each patient, to alter the topographical treatment zone size. While it's complex to equate a position on the cornea, though the pupil, to a position on the retina, 9 there does appear to be an emerging relationship between pupil size and myopia control in ortho-k. 7 The latest research indicates that the near-periphery (less than 20 degrees) is likely most relevant. 7 Limited research has been undertaken, though, on how much of the retina should be in myopic defocus, how far peripherally (or how close to the fovea) is important, or the pattern in which the defocus can occur. We know that the principles behind the myopia control effect of orthokeratology and multifocal contact lenses rely on image defocus - specifically, creating competing zones of retinal focus alongside myopic defocus to slow eye growth. However over one-third of participants were issued photochromic glasses, which were offered to parents concerned about side effects or pupil dilation - the authors note that these may have been taken up for protection against potential instead of realized side effects. Only 2% of the LAMP participants needed progressive addition spectacles and 5% reported photophobia, that didn’t require intervention. Some 60-70% of the children treated with 0.1% or 0.5% requested progressive addition spectacles, compared to 6% in the 0.01% group.īy comparison, the LAMP Study showed less than 1mm increase in pupil size for all concentrations, being 0.05%, 0.025% and 0.01%. All children in that study were offered photochromatic spectacle lenses - either single vision or progressive addition depending on near vision symptoms. The pupil size exceeded 7.5mm, on average, for both photopic and mesopic conditions with 0.5% atropine, was around 7mm for 0.1% and 5 to 5.5mm for 0.01%. The ATOM-2 Study, which compared 0.5%, 0.1% and 0.01% concentrations, 5 found an increase of around 3mm in pupil size for the stronger concentrations but only 1mm for 0.01%. There is a concentration-dependent response seen with atropine and myopia control efficacy, and the same is true for the side effect of pupil dilation. Studies are either very small, 2 have found no difference between myopic and control groups 3 or have contradictory findings on whether emmetropes have the larger pupils or not. While the IMI acknowledged a potential relationship between depth of focus, accommodative lag, retinal image blur and higher order aberrations in progressing myopes, they reported inconclusive data from published studies. 2 The IMI paper published in 2021 on Accommodation and Binocular Vision in Myopia Development and Progression concluded that the role of pupils in the development and progression of myopia is unclear. ![]() 1 Another small study in 2009 concluded there was no relationship linking pupils, myopia and accommodation. There is, however, still a lot to learn.Ī 2020 study on university students in Nigeria found that there was a statistically significant relationship between pupil size and myopia however they only reviewed 100 myopes aged 18-25 years. It seems reasonable to conclude that as the pupil controls the light input to the retina, and we now understand the strong link between focus, light and myopia risks, that the pupil might potentially hold the answers to many of our myopia mysteries. Pupils may be connected to myopia management more than we realize. ![]()
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