As myopia progresses, it causes significant damage to the eyes and the dimensions of the eye change.
1. The eye is elongated, from a ball-like shape to an egg-like one.
2. The front lens of the eye (Cornea) becomes erect, tapering forward.
3. The front lens of the eye, the cornea, becomes thinner.
4. The thinned cornea wrinkles and astigmatism occurs.
5. The sclera, the white layer outside the eye, becomes thinner, and the strain of the eye causes astigmatism with the pressure of the external muscles of the eye.
6. The retina becomes thinner. As a result, cracks, cracks and holes occur.
7. At the base of the eye, the vascular layer, the choroidea, becomes thinner, and as a result of the deterioration of the vascular system, areas that are not fed are formed.
8. The structure of the vitreous of the middle water of the eye is disturbed, and spots that impair vision occur.
9. The structure of the lens deteriorates, cataract (Curtain) comes 10 years earlier.
10. Eye pressure develops, eye pressure starts 10 years earlier.
EVALUATION OF MEASUREMENTS MADE FOR MYOPIC:
Have your eye measurements done, some issues need to be evaluated: The vast majority of myopia is axial myopia.
Measurements are normal but myopic: The anterior posterior diameter of the eye and the corneal hump are normal, but the eye may be nearsighted. This is in the refractive myopic group. There is excessive refraction and index change in the lens and cornea.
To evaluate anterior posterior diameter elongation:
Age: When evaluating the anterior posterior diameter of the eye, elongation according to age should be considered. 16 mm in baby. The anterior posterior diameter gradually increases.
Elongation: As the number progresses in myopia, the anterior posterior diameter of the eye lengthens and can reach up to 30 mm. 1 mm elongation causes 3 degrees of myopia. As the eye gets longer, the point of view falls in front of the fovea. The longer it gets, the longer this interval gets, and the clarity is lost.
In myopia, the anterior posterior diameter of the eye should be measured absolutely. This determines the ciliary or axial period and guides the ophthalmologist on what to do. As the age progresses, the anterior posterior diameter of the eye progresses between 16-22 mm. The anterior posterior diameter of the eye is determined for each age. 22 mm is the final distance of the anterior posterior diameter of a person aged 24 years and over. It grows to 28-29 mm in myopia.
Compensation mechanism of the eye:As the eye lengthens, protective measures develop to compensate for vision:
*Changes in the structure of the lens inside the eye.
* Strengthening of focus and adaptability.
*Differentiations in the refractive environments of the eye enable to see with less number.
The eye’s anterior posterior diameter is long, the number of glasses is low:Although some eyes are elongated, they see with less number.
* Congenital eye anterior posterior diameter is long. Like big hands. Eye structures adapted to it. Progress should be monitored.
*Although it is elongated, the lens in the eye, which provides focusing, adapts very well and compensates for the defect.
Why is the elongation of the anterior posterior diameter of the eye important?
While the eye is like a ball, it becomes like an egg. At the time of elongation, the cornea becomes erect, thinning, wrinkling (astigmatism). Thinning of the retina in the posterior pole of the eye, separation of cells and tissues from each other causes cracks and tears in the future. This is the main cause of black floaters in the eye. 1 mm elongation causes an increase of 3 diopters in myopia.
Why is it important for the ciliary muscle to function normally?
A strong and normally functioning ciliary muscle allows vision without glasses. Normal vision of a myopic person is provided by making this muscle work.
As the glasses take over the functions: The strength of the ciliary muscle gradually decreases as glasses take over the focusing and adaptation functions. As it decreases, it is tried to be closed by giving more numbers, which means progress in glasses. The ophthalmologist should provide clear vision by giving exercises to strengthen the ciliary muscle instead of increasing the number.
Exceptions: In some eye diseases, myopia develops even though the anterior posterior diameter is within normal values. Here, the lens in the eye swells. ROP is one of them. Myopia develops up to 7-8 numbers. As a result of oxygen or laser application to the eye, the nutrition of the lens is impaired. If there is no myopia in the family and a suitable lifestyle is drawn, myopia stops at this level.
Diabetes, cortisone drugs, stress cause myopia when the anterior posterior diameter is normal.
Corneal examinations:Significant changes in the anterior lens cornea in myopia can be evaluated by corneal topography.
Corneal arch: It is around 7.80 microns. As it gets steeper and conical, it drops to around 720. It goes above 820 as it flattens out.
Forward elongation or flattening of the cornea: While the front lens measurement is around 780-790, it decreases to around 720 as myopia progresses. This refers to the steepening of the cornea. The smaller the number, the steeper it gets. The cornea becoming upright from its normal flat state is another indicator of myopic progression.
Flattening of the cornea means another disease. In axial myopia, the cornea becomes erect. In high and congenital myopia, the cornea is flattened.
*An eye in the 820 arch should be monitored for other diseases.
Corneal thickness: The thickness of the cornea is around 580 microns. As myopia progresses, the cornea also becomes thinner and may decrease below 500 microns. If the cornea is thick (6.0 micron and above), the structure of the cornea will not deteriorate and will not become erect. Elongation occurs at the posterior pole of the sclera, the white part of the eye. If the cornea becomes thin
*Astigmatism occurs and progresses.
*If the cornea becomes thinner, laser application will be adversely affected in the future.
Thinning of corneal thickness.As myopia progresses, the thickness of the front lens of the eye, which is 570-580 microns in thickness, decreases as myopia progresses, and decreases to around 470-480 microns.
Why shouldn’t the cornea be thinned?
* As the cornea thins, a steepening occurs in its curve.
* Thinning of the cornea causes astigmatism. An astigmatized eye cannot see clearly like a normal eye, even if they wear glasses. Creep, elongation and floaters occur in images.
* Thinning of the cornea will make you lose the chance (!) of surgery to get rid of glasses with a laser to be performed in the future.
Retinal-choroidal thickness measurement: Retinal and choroidal thickness should be measured by OCT RNFL examination. This is the key to the treatment of the ophthalmologist for the prevention of retinal deterioration in myopia. Especially the nerve fiber layer of the retina should be evaluated well. Retinal thickness is 280 microns, retinal nerve fiber layer is around 110 microns. As myopia progresses, these thicknesses also get thinner. 200 microns and below are risky in terms of cracking and tearing. Since the choroid is not as flexible as the retina, significant defects occur.
Macular region examination.The fovea is the seeing point of the eye, the elongation in the anterior posterior diameter of the eye impairs its nutrition and causes structural defects in the cells that provide vision.
Condition of choroidea: The choroid becomes thinner as myopia progresses. The choroid is the vascular layer under the retina responsible for nourishing the eye. The elongation in the anterior posterior diameter of the eye also impairs blood circulation. The choroidea should be evaluated with OCT and normal blood flow should be established.
*The choroidea nourishes the retinal tissues. Insufficient nutrition in the vascular system creates damaged and destroyed atrophic areas. These areas see little or no vision.
* Since the flexibility of the choroidea is not as much as the retina, it cannot keep up with the elongation of the anterior posterior diameter of the eye. In places, areas where there is no retinal tissue appear.
Condition of the lens: Changes in the lens inside the eye cause myopia. If myopia occurs when the anterior posterior diameter of the eye and the corneal curve are within normal values
*The ciliary muscle is not functional enough. The decline in function is compensated by the lens. This is the ciliary period of myopia, instead of wearing glasses, the ciliary muscle should be made functional with exercise.
*Swelling in the lens is the cause of myopia. Diabetes, stress, cortisone drug use conditions that cause swelling in the lens should be investigated. Congenital swelling of the lens also creates myopia.
*ROP is an important cause of myopia, the eye number goes up to 7-8.
* Loosening of the fibers around the lens and the separation of some of the fibers cause inability to focus. This situation is tried to be eliminated by increasing the lake number.
Tear measurement: As the tear level decreases, the clarity of vision decreases. The effort to see causes the pressure of the external muscles on the eye, that is, the balloon phenomenon.
Thinning of the sclera: The sclera is the white layer that surrounds the eyeball. In myopia, the sclera becomes thinner. This means that the eyeball is warped, astigmatism occurs, and the anterior-posterior diameter of the eye increases further and myopia increases. In genetically myopic patients, there may be deterioration in the collagen fibers that provide the stiffness and resistance of the sclera. This causes the eyeball as a whole to grow in all directions.
Formation of astigmatism:Thinning of the cornea, distortion of the eyeball, imbalance between the eye muscles cause astigmatism due to wrinkling in the lens and cornea inside the eye.
Warping of the eyeball:The tightness of the eyelid, the pressure of the external eye muscles and the imbalance between these muscles cause a skew in the thinning sclera of the eyeball.
* Strain causes astigmatism.
*The deviation in the visual axis causes the image to fall out of the yellow spot. This causes a decrease in vision.
Changes in the eye due to progression in myopia:
Myopia is farsightedness and can be either refractive or axial type.
refractive type rare. There is a problem in the anterior lens corneal curve, the lens, the index of refractive media (light transmittance).
Axial type myopia: It occurs as a result of elongation in the anterior posterior diameter of the eye in school age. It is the most common type. What is described here relates to axial myopia.