What Is Orthokeratology?

The specially designed high-oxygen hard lens is used to flatten the center of the cornea through mechanical compression, the massage effect of lens movement, and the hydraulic effect of tear fluid to temporarily reduce the degree of myopia.

Orthokeratology

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The specially designed high-oxygen hard lens is used to flatten the center of the cornea through mechanical compression, the massage effect of lens movement, and the hydraulic effect of tear fluid to temporarily reduce the degree of myopia.

Western Medicine Name

The technical problems or guidance of the fitting staff are insufficient, or due to their own misunderstanding of lens care and use, they cannot regularly undergo regular review, and the use of lenses is not under effective monitoring. If the grasp of any link is not strict, there may be various complications related to orthokeratology. These complications mostly occur on the surface of the eye. ^[1]

If the corneal oxygen demand drops below a critical level, corneal glucose metabolism will switch to an anaerobic glycolytic pathway. Glucose breaks down into pyruvate and then forms lactic acid. Lactic acid cannot diffuse out of the cornea quickly. Therefore, as a result of aerobic metabolism, lactic acid accumulates in the cornea, the cornea becomes acidified, and the corneal stroma PH value decreases. In addition, the closure of the eyelids causes the accumulation of CO2 and the increase of PCO2, which causes tears and corneal stroma acidification, and reduces the osmotic pressure of tears. ^[2]

Slit lamp inspection.

People who meet the orthokeratology: generally over 7 years old, have a certain ability to take care of themselves, have parental supervision; corneal curvature ranges from 41.00D to 45.50D is better, too large and too small to correct; myopia degree is -0.75 ~ -6.00 Around D, the astigmatism is lower than -1.750D, and is astigmatic astigmatism. The effect of anti-astigmatic astigmatism is generally poor; patients below -4.00D are particularly recommended. Patients with low myopia who need good naked eye vision. Understand the mechanism of orthokeratology, its potential complications, and the limitations of correction; clear motivation and very good compliance; no corneal abnormalities, such as inflammation, degeneration, and other diseases of the eye; teenagers who have continued myopia child.

People who are not suitable for orthokeratology:

1. There is a certain misunderstanding on the understanding of orthopedic treatment, such as patients who think that this method can cure myopia unrealistically;

2. The expected value is too high, which is not consistent with the actual effect of the orthokeratology lens;

3. Eye diseases, such as patients with diseases on the surface of the eye, degeneration of epithelial cell matrix membrane, degeneration of endothelial cells, patients with recurrent epithelial cell spotting and severe dry eyes, infections, and inflammatory eye diseases

4, the refractive error is greater than -6.00D, astigmatism is contrary to the norm, astigmatism greater than -2.00 is not suitable for night wear;

5. Patients with significant intraocular astigmatism, and those with a refractive-to-refractive ball-to-cylinder ratio less than 2 need to be carefully considered;

6. Patients with large pupils, especially those with larger pupils at night;

7, young, poor self-care ability, poor personal hygiene habits;

8. Those who cannot complete the follow-up operation, those with poor wearing and follow-up compliance;

9. IOP is outside the normal range. ^[4]

Through timely treatment, there can be no serious eye consequences, but the combination of multiple complications exists. The light will affect the normal wearing of the patient, interfere with the study and life of the wearer, and the serious will cause serious irreversible eyes. Lesions that require long-term treatment. ^[1]

In the application of corneal shaping technology, the quality of lenses, the quality of fitting and the correctness of use by patients are inseparable safety chains. Any problem in any of these links will cause safety problems. ^[5]

Corneal epithelial damage, microscopic bubbles and corneal dimples, sterile corneal infiltration, foreign body invasion under the Ortho-K CL microscope, lens abnormalities, conjunctival inflammatory reactions, and allergic reactions. ^[1]

It has been reported in the early 1960s that wearing contact lenses, especially hard lenses, will cause the curvature of the cornea to change, resulting in astigmatism of 2.50-6.0D; the first generation of orthokeratology is based on the above clinical phenomena, Neilsen A hard lens that is 0.20 mm flatter than the flattest line of the cornea is used, so that the center of the lens is in contact with the cornea, which exerts a pressing force on the cornea and flattens the cornea. At that time, PMMA lenses were mostly used. Due to the poor oxygen permeability of such lenses, Can not be worn for a long time, the effect is not significant. In the early 1990s, a breakthrough in the material of contact lenses, the emergence of breathable rigid contact lenses, not only has good optical correction characteristics, but also has high oxygen permeability, DK / L value can exceed 100, can make The lenses can be worn for a long time without affecting the normal physiological functions of the cornea. At the beginning of 1997, the third generation of orthokeratology lenses appeared. Its main design is that the base curve of the orthokeratology lens is 4-6D flat than the central corneal curvature, and the lateral center arc is steeper than the base arc, which can have a difference of 4-16D, so only 1-2 pairs of lenses can quickly reduce 3-5D myopia. ^[6]

During 1998-2001, many wearers of orthokeratology had many complications, and the wearing unit was caught in medical disputes ^[7] . Several Singapore children were infected with Pseudomonas in 2006 ^[8] .