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Myopia, also referred to as short-sightedness, happens to be a visual dysfunction that prohibits the ability to see objects at a distance clearly or without the aid of glasses. Myopia usually appears early, mostly affecting school-going children. As per a study by the All India Institute of Medical Sciences (AIIMS), 1 out of 6 children between the ages of 5-15 years are suffering from myopia in India. Different studies have shown that people with nearsightedness, where the onset of the disease has occurred before the age of 20, are at an increased risk of developing cataract formation.
While the exact cause is not clear, it is believed that as the axial eyeball length (the length of the eye from the front to back) increases in myopic eyes, it may prevent nutrients from reaching the backside of the lenses.
This causes people to lose their clarity and the formation of cataract begins. While surgery is one of the most effective ways to deal with cataracts, highly myopic eyes pose additional risks and challenges.
People who suffer from high myopia are at an increased risk with regard to cataract surgery as:
Removing cataracts surgically becomes increasingly complex, complicated and risky when the person has high myopia. As the eyeball is overstretched, it becomes all the more difficult to precisely calculate what should be the power of the replacement lens. This may lead to less reliable results and even lessen the procedure success rate. Other than that, a number of eye conditions may also occur during the surgery.
Highly myopic people also have a much higher risk of retinal detachment during cataract surgery and after, due to the shape of the eyes. It can also significantly increase the risk of vision loss if proper precautions are not taken.
Given the increased risk of complications in high myopia patients, surgeons need to carefully weigh the benefits and risks of performing an operation. As compared to emmetropic eyes (with no refractive error), myopic eyes have a greater risk of retinal complications, like retinal detachment. Therefore, it becomes imperative for the surgeon to look for any sort of retina breaks, weakness of eyes or holes.
Other than that, people with high myopia may also suffer from epiretinal membranes (a fibro-cellular tissue that forms on the inner part of the retina), macular degeneration or other major changes. All these can limit the vision achieved through surgery and may influence postoperative complications like cystoid macular edema (a painless disorder that affects the central macula or retina).
Apart from the usual cataract evaluation, it is essential to take care to assess the retinal status accurately and measure the eye’s axial length. A high nearsightedness can also have a posterior staphyloma (a condition that is commonly observed in highly myopic patients with long axial lengths), which can lead to an erroneously long axial length after it is measured with the standard A-scan ultrasound. This can cause a mistake in lens calculations as well lead to the development of other eye issues that can ultimately affect the patient experience. Therefore, it is always best to use an optical method for measurement as it tends to be more accurate.
While cataract surgery is an effective way to get rid of cataracts, for patients with high myopia, careful precautions, as well as sufficient follow-ups, are of great importance because of the higher chances of developing intraoperative and postoperative complications.