Myopia is a visual impairment when a man has a good near vision and a bad distant vision. Light rays coming into the eye are focused not on the retina but in front of it. In the result distant objects seem not distinct, diffuse.
Reasons of origin
- Cornea and the lens refract light rays too strongly.
- The eye is too long. Normal eye length of an adult is 23-24 mm but with myopia it reaches 30 mm and more. Lengthening of the eye by 1 mm leads to augmentation of myopia by 3 diopters.
Three levels of myopia are recognized:
- Weak – up to 3 diopters
- Middle – from 3 till 6 diopters
- High – more than 6 diopters
Why myopia develops
There are several reasons that give rise to origination of myopia. Among them:
- Excessive eye work at closer distance from the object (without having rest for the eye and by bad illumination).
- Hereditary predilection that is manifested in peculiarities of eyeball construction and metabolism in it.
- Weakened sclera that cannot offer resistance to excessive growth of the eye.
- Insufficiently developed accommodative muscle of the eye responsible for adjustment of the lens for various distances. Overstrain of the weakened muscle can also lead to myopia.
In case of progressive myopia an operation called scleroplasty is carried out; straps of biologic material are introduced behind the eyeball, they wrap the ball like a bandage and restrain further sprain. Besides scleroplasty stimulates augmentation of quantity of blood vessels that feed back pole of the eye promoting the support of high vision functions.
Scleroplasty may be carried out on the outpatient basis, the duration of operation varies from 5 to 15 minutes.
Progress of myopia may lead to irreversible changes both in central divisions of retina and on the periphery of eye bottom. If peripheral dystrophies of retina that contain a potential risk of retina detachment are discovered, the patients undergo lasercoagulation – prophylactic strengthening of retina in dystrophy zones. A laser ray “welds’ retina to the choroid in weak places and around its ruptures. Operation is made on the outpatient basis and takes 10 – 15 minutes. Lasercoagulation can be done on both eyes simultaneously.