Insight into myopia and myopia pathology
The condition known as myopia, or short-sightedness, causes your vision to become blurry at a distance, while being clearer at close range.
Most people with myopia have healthy eyes and can easily correct their vision with glasses or contact lenses. It is a very common focusing problem, and people with myopia are the most likely to correct it with glasses or contact lenses.
There is a difference between pathological myopia and simple short sightedness. Myopia caused by pathological conditions is extremely short-sighted, resulting in degenerative changes to the back of your eye. Myopia resulting from pathology can cause significant reductions in sight that cannot be corrected by glasses or contact lenses.
What is myopia?
A clear vision requires accurate focused light entering the eye on the retina. This is accomplished by the cornea focusing the light entering your eye, followed by the lens finely focusing it. As light enters your eye, this focusing system should ensure that as it reaches your retina, it is sharply focused, which will result in everything being in sharp focus without any blur.
The vision of a person suffering from a “refractive” or focusing error is blurry if light is not properly focused onto the retina of the eye.
Those who suffer from myopia experience blurry vision as light entering the eye comes to a focus point before reaching the retina. This can be caused by lengthening of the eyeball or steepening of the cornea.
For people with myopia, a prescription should be obtained for glasses or contact lenses with a minus lens power to correct their vision. This lens reduces light’s excessive bending by the eye, focusing it directly onto the retina, resulting in clear, crisp vision.
How is myopia graded?
The focus power of your eye is measured in diopters by Optometrists, which is a technical term that indicates the strength of the lens you will need to correct your vision and provide you with clear vision.
If you have myopia, your prescription will be written with a minus power; for example, if your prescription is -3.50 diopters (D), indicating that your lens corrects for myopia. The minus sign indicates that your lens is correcting for myopia. If you have a high number, you are considered shortsighted.
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The term “mild myopia” includes powers up to -3.00 diopters (D).
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Myopia of moderate severity, with a power of -3.00D to -6.00D.
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In general, high myopia is defined as a power greater than -6.00D.
In most cases, people with myopia less than -6.00D are not afflicted with any further health problems. This is sometimes referred to as simple myopia, which means that your eyes are healthy and that a corrective eyeglasses or contact lens can easily correct the blurriness caused by your myopia.
High myopia
Irrespective of your myopia level, you may be at greater risk of developing the following eye conditions if your myopia is higher than -6.00D:
In spite of this, not all people who have myopia above -6.00D will develop other eye conditions, and for the majority of people, their vision will be intact.
The pathology of myopia
The condition of pathological or degenerative myopia is marked by very high myopia and the retina of the eye is also affected by degenerative changes.
What are the effects of pathological myopia on the retina?
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The retinal atrophy is the condition in which the retina becomes very thin and ceases to function.
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The lattice degeneration is the thinning of the retina at the far edges of the eye.
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Bruch’s membrane cracks – breaks in the membrane that connects the retina with its underlying blood supply (the choroid).
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(Myopic choroidal neovascularization) – The presence of new leaky vessels under the retina (the choroid layer), through lacquer cracks or in areas of retinal atrophy may result in the formation of new blood vessels.
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In myopic maculopathy, degenerative changes can occur at the center of the retina, the macula. Myopic maculopathy can seriously affect your vision in the central region of the retina.
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In the case of myopic choroidal neovascularization, the macula can be scarred, which can lead to blank areas or missing patches of vision in the center of your field of vision, known as Foster Fuchs spots.
Is there a treatment for pathological myopia?
Depending on the type of degenerative change that has developed, you may require different types of treatment. Unfortunately, all the changes that occur in pathological myopia, including retinal atrophy and lacquer cracks, cannot be treated.
With anti-vascular endothelial growth factor (anti-VEGF) treatment, you may be able to treat the development of new blood vessels at your macula. By inhibiting the growth of new, leaky blood vessels and oedema (swelling) caused by these vessels, anti-VEGF medications work. As a result of this treatment, scarring and damage to the retina can be reduced, reducing the risk of further deterioration of vision.
Do I have any options for preventing pathological myopia?
The complications of high or pathological myopia cannot be prevented by any treatment available if you have high myopia already. As a result, it is not possible to control how your eye grows. As of yet, no evidence suggests that diet, vitamins, or supplements have any effect on your chance of developing pathological myopia or making it worse.
You will be monitored regularly by your optometrist or ophthalmologist (hospital eye doctor) to make sure your eyes are healthy. Currently, treatment aims to improve your vision and to treat any complications that may arise. In the event of any changes to your vision or any new symptoms, it is essential to schedule an appointment with your optometrist or ophthalmologist as soon as possible.
What can I do to improve my vision?
There are no complications associated with myopia in most people and they are only required to wear glasses or contact lenses to enhance their vision. A NHS complex lens voucher can be used towards the purchase of glasses or contact lenses if your prescription exceeds -10.00D. Depending on your prescription, your optician will be able to inform you of the value and eligibility of this voucher.
If your retina is damaged, then you may need more than glasses to correct your vision if you have myopia. If your level of myopia is high, you are at a higher risk of developing eye conditions associated with myopia and pathological myopia.
Making the most of your vision with low vision assessments
An assessment of your low vision may explore how to maximize your vision. Your GP, optometrist or ophthalmologist can refer you to your local low vision service for an assessment. This may involve making things larger, using brighter lighting, or using colour to make things easier to see.
Sensitivity to light
Photophobia is a common symptom of pathological myopia in which a person finds themselves sensitive to light, or may be unable to adjust to changes in light levels. In order to reduce the discomfort and glare you may experience in everyday life, you may wish to use sunglasses, tinted lenses and sunshields.
When driving
In the event that you have pathological myopia or an eye condition caused by high myopia, you may experience vision problems that cannot be corrected by spectacles or contact lenses. It is mandatory that you inform the Driver and Vehicle Licensing Authority (DVLA) if both of your eyes are impacted by the changes. You may be permitted to continue driving if the DVLA has approved your sight. In order to determine whether your vision meets the DVLA standard or if you need to notify the DVLA of your sight problems, you should consult your optometrist or ophthalmologist.
