WHY DOES IT MATTER?
Pathological Myopia
Degenerative myopia (aka. pathological myopia) is a condition that usually is present at birth or first develops in children under the age of 13.
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The condition is caused by the gradual lengthening of the eyeball and results in a high amount of myopia by late teens to early twenties.
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As patients with myopic degeneration get older, the condition worsens.
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50% are considered legally blind by the time patients are in their 60's.
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The eyeball continues to elongate, the sclera and retina thin due to the stretched walls of the eye.
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A simplfied way to visualize this is to imagine blowing up a balloon, as more air is put in the balloon and it continues to stretch it becomes more likely to pop
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This puts the patient at risk for retinal holes, tears and detachment (assessed with dilated eye exam).
Risks Associated with
High Myopia
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Stretching
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Most, but not all of the problems seem to occur due to this stretching process as the eyeball elongates. The sclera (the white of the eye), the choroid (the layer of blood vessels supplying nutrients to the eye), the retina and the connective tissue between the retina and the vitreous are all stretched and weakened.
Stretching of the retina increases the risk of retinal detachment, lattice degeneration, retinal holes, thinning and damage to the various layers of the retina: photoreceptors, Bruch's membrane, choroid layer, etc.​
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Staphyloma
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​At the macula the stretched choroid layer develops characteristics of macular degeneration with scarring occurring at the macula. The elongation causes a staphyloma behind the macula pushing the macula out of alignment and causing a profound myopic condition.
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Intraocular pressure
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To complicate things further, due to the changing shape of the eye, the drainage process through the trabecular meshwork (where the aqueous fluid drains) can also contribute to the elongation of the eyeball shape (the intraocular pressure may remain still within the"normal" range).
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Cornea
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In addition, the cornea becomes thicker and more rigid. This creates multiple additional problems. First, the thicker cornea makes it more difficult for an eye doctor to detect development of glaucoma. Second, the cornea itself plays a role in focusing. In fact the correct alignment of fibers within the cornea contribute 65% to 75% of the focusing ability of the eye.
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Retina
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the retina can thin and increase the risk of a retina tear, break or detachment​
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Vitreous
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​The vitreous gel may thin and liquefy increasing the risk of vitreous detachment.
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