Updated: Jun 8, 2021
The prevalance of of myopia has nearly doubled in last 20 years and those who were high myopic in 1970s are now on the cusp of experiencing sight-threatening complications. Studies says that 50% of the world's total population is estimated to be myopic(near sighted) in next 30 years. Children of today are more likely to get affected by myopia induced visual impairment later in life. There are many pillars to control myopia and Orhthokeratology proves to be the most effective pillar.
I had been frequently asked as how doing a corneal reshaping treatment will control myopia progression and visual impairment as cornea(black portion) is in front of the eye while the most of the sight threatening complications due to myopia happens more in posterior part of eye, the retina.
When a child is corrected with traditional methods of refractive correction by single vision spectacle or contact lens, the central rays gets focused on retina and the child is able to see clearly. But we are ignoring the peripheral rays which gets defocused and falls beyond retina (Hyperopic defocus). The peripheral signals from retina dominates than the central reflex in brain forcing eye to grow more towards peripherally focused rays. The axial length of eyes increases as the result of periperal hyperopic defocus.
The complications causing Visual impairment due to myopia are related to increased axial length of eyeball.
The average growth in axial length and increase in power can be elicited from the below table.
Myopic Macular Degeneration and Retinal detachment are the most devastating and have the strongest relationship to myopia and longer axial lengths. Other complications include Primary Open Angle Glaucoma, Cataract and etc,. Each diopter increase in myopia results in 67% increased risk of Myopic Macular Degeneration in later years of the child.
In Orthokeratology, unlike traditional spectacle correction, the image shell is formed inside retina so that the eye is forced not to grow. When elongation is halted, the axial length doesn't increase.
Controlling axial length elongation arrests not only power progression but also prevents eye from Myopic Macular Degeneration, Retinal Detachment, Posterior Staphyloma, and etc which are caused due to stretching of eye ball.
The risk of visual impairment due to the above mentioned causes increases from 3.8 % in eyes with axial length less than 26 mm to 90% in eyes with axial length of 30mm or greater. Thus Corneal Reshaping with Orthokeratology controls myopia progression, axial length growth and its complications effectively.