There’s definitely a connection between two of the most common visual impairments, nearsightedness (myopia), which currently affects around 3 billion people globally (and projected to reach 5billion by 2050, and cataracts which already form in the eyes of 90 percent of elderly citizens, as well as in some young children, says Australian master of optometry and fellow of the International Academy of Orthokeratology and Myopia Control (FIAOMC), Gary Rodney.
He says that while it is hard to determine exactly how far that connection goes, indications are that both myopia and cataracts do indeed affect each other in terms of levels of severity. And both may individually be the cause of the other one’s development in certain situations. But, like the never fully answered question about which one comes first, the chicken or the egg, there is no definitive answer to this mystery either.
How Myopia Can Affect Cataract Development
Rodney said that in most cases, when people start to see their vision cloud over and become blurred as they develop cataracts on one or both eyes, it is because of a protein build up on the lens or lenses, a process which is seen as a natural part of aging. However, high myopia has been shown to often have a hand in when and if this happens. Statistically, having high myopia can double the risk of these fuzzy invaders blurring the lenses, and it can also lead to cataracts starting earlier in life.
Types of Cataracts
There are three types of cataracts, the nuclear cataract which develops in the center of the eye; the cortical cataract which is wedge-shaped, starts at the edges of the lens and progresses towards the centre; and the posterior capsular cataract that forms behind the lens and blocks light from reaching the retina.
It is also possible for babies to be born with congenital cataracts or for them to form in the first year of life, a situation which parallels a similar pattern to that of myopia development in some cases.
A Misleading “Holiday” from Reading Glasses
According to Rodney, those with high myopia are more prone to developing nuclear cataracts. And, strange as it may seem, the development of the cataract, either in the same place or behind the lens, itself has a tendency to cause a refractive change towards myopia, called a myopic shift.
This actually improves the close-up vision of some of the elderly, giving them hope by removing their need for reading glasses – for a while. Sadly, this so-called Second Sight is more of a brief reprieve rather than a long-term fix and doesn’t usually last very long, Rodney says.
Research shows that the myopic shift happens in both nuclear cataracts (low to mild grade) as well as with posterior subcapsular ones of a mild to advanced grade, and can achieve an average improvement of best corrected visual acuity (BCVA) of 20/43 to 20/32, as well as showing a noticeable shift towards myopia which also increased with the cataract’s stage of development.
Currently, promising research is being done into eye-drops that contain a natural compound called lanosterol, which researchers suggest may dissolve cataracts. This natural compound already exists in the eye lens and is responsible for keeping the lens transparent.
At present surgery is the standard procedure used to remove and replace the damaged lens. However, there again, high myopia can interfere, causing complications in surgery such as retinal detachment or possibly causing a variable postoperative refractive error which removes the ability to see a few inches away. A second operation may be needed to correct this.
For more information visit the Smart Vision website: Optometrists Sydney: Optometry Services For Children and Adults | Smart Vision; for specific information about Myopia treatment and prevention visit Myopia Prevention: Solutions, Control And Treatment In Sydney; and for detailed information about Myopia Treatment visit Orthokeratology In Sydney: The Non Surgical Alternative.
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