In part one of “Can We Cure Nearsightedness” we discussed myopia, its incidence and the expected increase over the next 30 years. Currently there are a number of clinical approaches to preventing or slowing the progression of nearsightedness. These approaches include spending more time outdoors, reducing the focusing demand on the eyes by holding reading or gaming materials at a specific distance, or by frequently looking in the distance to relax the eyes. To make sure the eyes are relaxed while performing near work, reading or computer glasses are also an option. New to the market this year, MiSight, a specialized soft contact lens not only corrects distance vision, but it also reduces the stimulus causing the progression of myopia. Orthokeratology, which has been around for years, uses a specially designed gas permeable contact lens patients sleep in the lens to reshape the steep curvature of the eye resulting in reduced nearsightedness. There is also a pharmaceutical option. Low-dose Atropine drops can be used on a daily basis to slow myopia progression. These options may be used alone however, for the best outcome are used in combination
Two of the simplest ways to reduce the progression of myopia with the least amount of effort would be to have your children spend more time outdoors and/or control their accommodation. Accommodation is the ability of the eye to change its focus from distance to near objects (and vice versa). This process is achieved by the lens of the eye changing its shape and the eyes converging together as a person looks up close. The closer the reading material is to the face the more accommodation and convergence is required.
With respect to spending more time outdoors studies revealed that for each additional hour per week that children spent outdoors, their risk of being nearsighted dropped by two percent. Nearsighted children in this study spent on average 3.7 fewer hours per week outdoors than those who either had normal vision or were farsighted. The study also investigated whether children who logged more outdoor time also spent less time performing near work, such as playing computer games or studying, but no relationship was found.
Another study showed that the rate of eye growth in children (axial length) varied in relation to exposure to daylight. As described in last week’s article, the longer the eye or axial length the more likely the person is nearsighted. In the study, children’s eyes grew normally during the long days of summer, but grew fast during the short days of winter. The benefit of spending more time outside appears to be related to exposure time to daylight, but the exact reason is unclear. It was clear though, that the children who spent more recess time outdoors were less likely to become nearsighted.
Reducing the amount a child has to focus or accommodate during near work has long been theorized to slow myopia progression. Although the clinical value of this is limited, it does have some effect. This can be accomplished by having the child keep his or her reading distance at what is termed the Harmon distance. The Harmon distance is the distance from the eyes to the patient’s elbow while the fist is on the chin. In addition practicing the 20/20/20 rule further relaxes the accommodative system for brief periods. Children are educated to look 20 feet away, every 20 minutes, for 20 seconds.
Counselling children and teenagers to perform these habits are limited in success. Therefore, prescribing reading or computer glasses for the same effect of reducing accommodation can be beneficial. There are many designs of reading or computer glasses; single vision, bifocals, blended bifocals and progressives. Non-glare and blue light blocking lenses add additional comfort for these lens designs.
These are just some of the clinical approaches to reducing myopia progression. Over the next two weeks, we will discuss MiSight soft contact lens, orthokeratology and low-dose Atropine. If you missed Part I of Can we Cure Nearsightedness we invite you to visit our website to view it at www.cockrelleyecare.com. If you have questions about our articles please contact our office in Stillwater at 405-372-1715 or message us on Facebook at Cockrell Eye Care Center!