What is myopia. Causes and methods of slowing it down.
Myopia is a refractive error, which is manifested by the inability to clearly distinguish the objects located at a distance, while nearby objects are clearly visible. Myopia occurs frequently around the age of 6-8 years, by excessive and progressive elongation of the anteroposterior axis of the eye, the image of objects focusing in front of the retina. The incidence of myopia in the world has increased significantly in recent years. This growth is influenced by both genetic and environmental factors. Genetic research has identified more than 20 genes responsible for myopia, supporting evidence which show an increased risk of becoming myopic by 2-8 times if one or both parents are myopic.
The short time spent by the child outdoors (less than 2 hours/day), the long time spent in front of the screens (phone, tablet, computer, TV) and the incorrect position when writing/reading have a significant impact on the evolution of myopia. In addition, the age of myopia onset has decreased significantly.
Efforts to reduce the progression of myopia in childhood are motivated by the increased incidence of high myopia and its associated risks: retinal detachment, cataracts, glaucoma.
Fortunately, there are ways to slow down the progression, these being:
- atropine in the form of drops
- multifocal contact lenses
- rigid contact lenses -ORTHOKERATOLOGY
They can decrease the progression of myopia by up to 40-60%.
The choice of method is made taking into account several factors, the most important being: the age of the child degree of myopia and pupil size.
Atropine
In the child aged between 6-9 years, atropine administered 1 drop/day in the evening is the easiest and at the same time effective prevention method. The solution used has a very low concentration of only 0.01%, unlike the one used for over 100 years in the treatment of amblyopia (lazy eye), which is of 1%. The mode of action and the place where atropine acts to slow myopia are not yet fully elucidated. Some hypotheses claim that it binds to certain receptors influencing scleral remodelling.
Studies have shown a higher efficiency of the 0.01% concentration as compared to 0.1% or 0.5%; in case of these higher concentrations a rebound phenomenon (return of progression to the previous rhythm) after discontinuation of treatment was found. In addition, the side effects observed at concentrations of 0.1% and 0.5% (pupillary dilation, photophobia, loss of crystalline accommodation and impaired vision) were not noticed in case of the 0.01% concentration.
In atropine 0.01%, pupillary dilation is below 0.7 mm and close vision is not affected, thus being much better tolerated and having therapeutic effects similar to or even superior to higher concentrations. In conclusion, 0.01% atropine is a method that is both inexpensive and proven by multiple studies to be safe and very effective in controlling myopia. Oftapro Clinic is the first clinic in Romania in which this method of control is accessible to patients since 2015.
Contact lenses
Soft, multifocal contact lenses are worn during the day and can cause a slowdown in the progression of myopia by about 40-50%, by changing the peripheral refraction of the eye (peripheral defocus). These are specially designed contact lenses with a distance dioptre located in the centre of the lens and a lower dioptre at the periphery with 1.5-2.5 dioptres. Children who wear these lenses no longer need glasses during the day, but must follow the rules of wearing and maintenance specific to contact lenses. The age at which these lenses can be prescribed to children is over 8-9 years.
Orthokeratology (Night Lens) can achieve, according to studies, a slowdown in the progression of myopia of about 50-60%.
During sleep, wearing a specially shaped gas-permeable night contact lens (RGP) achieves a temporary gentle remodelling of the cornea. Thus, after removing it on waking, the vision remains clear throughout the day and it is no longer necessary to wear glasses or other contact lenses during the day. These lenses should be worn for at least 6-8 hours a night. The effect is totally reversible after 48-72 hours after stopping wearing them, but it is necessary to apply it every night in order to keep the benefits obtained.
They are especially indicated for children over 8-9 years old, with dioptres up to – 7 D, with an astigmatism under 3 D, motivated to follow the schedule and wearing rules.
In general, wearing contact lenses is associated with a slightly higher risk of conjunctivitis or corneal erosions, therefore it is important to follow all hygiene measures and instructions received from your doctor.
Age should not be seen as a rigid criterion, more important being the child’s attitude and the degree of parental involvement. Children can become contact lens wearers when they are sufficiently motivated, responsible and able to strictly adhere to hygiene. Another very important aspect is the support from the parents.
The ophthalmologist must take the initiative and propose contact lenses for children. Due to the lack of information, many parents believe that their little ones can only wear lenses from the age of adolescence. Often, children are very excited about this opportunity. They are able to care for the lenses and benefit a lot from wearing them, which makes them excellent candidates for contact lenses.