Myopia

Myopia is a common refractive defect in which patients cannot see objects in focus in the distance but can see well up close. In this case the eye is too long or the cornea/crystaline combination is too curved. The light rays are thus focused in front of the retina, resulting in a blurring of what is further away. The vision of objects closer to the eye is sharp.

It is an often familiar defect and tends to increase with growth, stabilising in early adulthood most of the time. It will therefore be higher the earlier it manifests itself.

According to the Myopia Institute, myopia has been increasing due to the conditions of modern life, for example the overuse of mobile phones and other devices, and it is estimated that in the future about 50% of the population will be myopic, compared to 30% today. It may thus become the most frequent cause of reversible blindness worldwide due to the complications inherent to the pathology (retinal detachment, glaucoma e cataract).

Patients cannot distinguish distant objects that are very blurred, they close their eyes to see better, they have headaches due to the effort, they see even worse at night.

Children tend to approach screens and books and remain oblivious to what is going on in the distance. Although nowadays everyone gets close to their mobile phones and remains oblivious to what is going on around them, it is still a signal to heed.

The greater the myopia in a child the greater it will be when they reach adulthood.

Adults with myopia have a higher frequency of retinal detachment. The greater the myopia the higher the percentage. In the case of malignant myopia this possibility is high.

Malignant myopia is a disease. The eye is very large, sometimes has deformation of the posterior wall (staphyloma) and are generally eyes with myopia between 20 and 30 dioptres which have retinal changes due to stretching of the retina because of its size. These alterations often lead to the appearance of tears and consequently to retinal detachment.

High myopes are also more likely to develop cataracts. Current data shows that myopes who have undergone cataract surgery have a 2.5% incidence of retinal detachment in the years following surgery, as they more often have changes in the retinal periphery that predispose them to such pathology. This compares with 0.5% of those operated on without any refractive error.

Another complication that is more frequent in myopic patients is the appearance of glaucomaglaucoma, especially from the fourth decade of life onwards.

Early diagnosis is really important because the development of vision is directly related to that of the child and its brain. By the age of four the eye-brain relationship is practically finalised. This factor is important because in cases where myopia is unilateral or much greater in one eye than the other the eye is subject to amblyopia (low vision eye) which is difficult to treat from this age.

It is not always easy to diagnose a myopic person. If a child is short-sighted they can see well enough for everyday life as they can see well at close range, the distance is blurred, but this is normal for them as they don't know what it is like to see well, so they don't complain and can go unnoticed until they reach school age. When they arrive in class and can't see the blackboard, they discover their problem. This situation is less frequent nowadays. Paediatricians and parents are more alert to the signs and to pre-school screening, especially when there are cases in the family.

Embryologically the eyes derive from the brain and are basically an extension of it. It is the brain that sees and interprets the signals sent by the eye as an image.

Hence the importance of early diagnosis, because the brain, used to receiving a blurred image, then has difficulty discerning a sharp image with the appropriate optical correction.

The diagnosis, once the deficiency is suspected, is made by the ophthalmologist by means of observation with measurement of the visual acuity and refraction.

Treatment often boils down to a prescription for spectacles in the first approach. Later on contact lenses may be prescribed. These have the advantage, apart from aesthetics, of giving the patient a more natural vision in terms of field of vision and size of objects. Myopic spectacle lenses greatly reduce the size of what we see around us. Myopic people wearing contact lenses for the first time often find it difficult to adapt to their new way of seeing. The opposite is even more evident and difficult to bear. The habitual contact lens wearer, when faced with the need to wear glasses, even temporarily, will see the world around him as very small and will find it very difficult, initially, even to move around.

Myopia is the most frequent reason for a refractive surgery consultation, because LASIK. Once the decision has been made, the ophthalmologist will have to make sure if you are a good candidate, or rather if the candidate's eyes are fit for surgery.

There are several factors to consider:

First of all age. A patient under 18 years of age will not yet have stabilised myopia and even older patients may not be. So the ideal is that the clinical history shows that there is already a stabilisation for at least two years. Otherwise we will operate on the patient who will be at any degree of myopia. If the myopia is not stabilised, myopia may appear again over time, although it may be smaller than in the beginning. The clinical history should also reveal any systemic diseases that may jeopardise the surgery, such as collagen diseases (Lupus, scleroderma and others), which can cause structural disorders of the cornea.

Secondly, the evaluation of the degree of myopia and the study of the cornea with regard to the existence of astigmatism, thickness and regularity of the surface, aberrations and the detection of ocular dryness (or dry eye) A corneal topography has a very important role here because it allows us to evaluate all the parameters mentioned, except dry eye.

Dry eye is evaluated by means of the Schirmmer test (evaluates the amount of tears in a 5min period). It is a very simple test performed in the office. On the other hand, at the CPO Clinic it is possible to do a test to evaluate the presence of dry eye and tear quality called Tear Check.

If there is no contraindication the patient is then referred for surgery by LASIK. The main issue for the decision has to do with the corneal thickness.

As corneal tissue must be removed to shape the cornea with the excimer laser, the relationship between the degree of myopia (plus any astigmatism concomitant) is fundamental. It is not possible to go beyond certain thickness limits, otherwise you may have problems that are difficult to solve later on (corneal ectasia). In some cases we can use another technique with excimer laser or PRK, which allows us to save a little more corneal tissue.

If we have exhausted the possibilities of laser surgery, we can resort to phakic lens surgery, the surgery with the primary indication for the highest myopia, above 6 diopters.

When the patient is myopic around the age of 50, the best option is to replace the lens with an EDOF intraocular lens (Extended Focus Lens), which has excellent visual results at any distance, with the help of minimal monovision, that is, we leave the non-dominant eye with a slight myopia that favours close vision.