Monday, October 28, 2013

Orthokeratology (Ortho-K) - A New Advent


What is orthokeratology?

Source: www.commons.wikimedia.org
Orthokeratology or ortho-K is a new advent in the field of ophthalmology and optometry. It refers to a non-surgical and reversible ophthalmological procedure where specially designed gas permeable contact lenses are used to reshape the anterior surface of the cornea in a gradual and gentle way. It is a kind of vision therapy where cornea is molded according to the type of refractive errors which are myopia (near sightedness; the patient can see clear near objects but not the far ones with accommodation of eyes at rest), hypermetropia or Hyperopia (far sightedness; the patient can see clearly far objects but not the near ones with accommodation at rest), astigmatism (inability of eye to make a sharp focused image of a point object onto the retina, a blurred image is formed) and presbyopia (inability of eyes to focus near object with advancing age).
Ortho-K lenses are worn during sleeping hours only. In other words, these are overnight wear lenses and not to be worn on waking hours. They are removed on waking up and the reshaped surface of the cornea allows clear vision for waking hours without wearing spectacles or contact lenses. 
Orthokeratology is recommended for both children and adults with refractive errors ranging from -1.00 to -10.00 dioptres of myopia and from +1.00 to +5.00 dioptres of hypemetropia as well as for low degrees of astigmatisms. In some countries hyperopic Ortho-K contact lenses are not available but low degrees of astigmatism and myopias are corrected as given in the ranges in this paragraph.
It is a non-invasive and reversible as compared to LASIK eye surgery which is invasive and can permanently change the shape of cornea. So, people who avoid undergoing eye surgery for their refractive errors can get benefited from Orthokeratology.

Who are the best candidates for ortho-K therapy?

  • Children are the best candidates for Ortho-K treatment as their myopia progression control is good with Ortho-K. Researchers in Hong Kong and the US have conducted clinical studies which revealed that children who wear Ortho-K lenses had 50% less progression in myopia than children who wear spectacles and contact lenses.
  • Sportsmen
  • Dry eye complain with contacts
  • People who are allergic to contact lenses
  • Dusty or hot environment which is not suitable for contact lenses
  • Cosmetic purposes for getting rid of spectacles
  • Contact dermatitis with spectacle material

How orthokeratology works? 

During sleep Ortho-K lens reshapes the cornea inserting fluid forces (i.e. hydrostatic pressure) to conform the cornea to the lens’ reverse geometry design. It produces a flatter central cornea and steepens the peripheral cornea correcting myopia.
For hypemetropia and presbyopia the cornea is conformed to the contacts lens’ double reverse geometry design steepening the central cornea and flattening the peripheral cornea, correcting hypermetropia and presbyopia.

Duration of ortho-K therapy 

It varies from patient to patient and client to client and compliance of wearing the Ortho-K lens. Patients can get required results in a fortnight wear, but normally follow up visits are needed by patients till 4-6 months from the 1st day wear of Ortho-K lens. In other words, you can get rid of eyeglasses by ortho-k technique.

Expectations from the therapy

  • Orthokeratology only treats refractive errors but does not cure them.
  • The results may be reversed if patient does not wear the specified lens in continuous period of 3 days.
  • If there is any unexpected result, client must visit the practitioner although it is not scheduled.
  • Vision may be fluctuating during the treatment and after refractive error is reduced by Ortho-K lenses, in the later case, it may be the result of not placing the lens correctly as required in case of myopia, hypermetropia and astigmatism

Contraindications of Ortho-K lenses

  • Acute and subacute inflammations or infections of the anterior or posterior segment of the eye.
  • Any ocular or adnexal abnormality which may affect the eyes
  • Severe insufficiency of tears - dry eyes, Sjorgen’s syndrome
  • Corneal hypoesthesia
  • Any systemic disease that exacerbates on wearing the lenses.
  • Allergic conjunctivitis
  • Keratitis - bacterial, fungal or viral.
  • Hypersensitivity by lens solution

Orthokeratology cost 

Orthokeratology cost in Pakistan is near abput 60,000 PKRs for low myopia for both eyes. Thus, it is cost effective as compared to LASIK eye surgery which, on average, costs 7000-80000 PKRs. 
In USA, average cost of Ortho-K is 1300$-1500$ for both eyes for low myopia and for single eye it is 1000$. Average cost for high myopia in USA is 1500$-2000$ for both eyes and1200$-1500$ for single eye.

By:
Nishat Akram
(Doctor of optometry- Optometrist)


Keywords: Orthokeratology, Ortho- K, Contact lenses, Vision, Eyeglasses, Lasik eye surgery, Myopia, Hypermetropia, Astigmatism, Orthokeratology cost

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