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Frequently Asked Questions

Is everyone a candidate for Ortho-K?

No! While Orthokeratology can help most individuals (including those with [[astigmatism]] and moderately high [[myopia]]) improve their vision, the procedure is often most effective for those prescriptions falling within a specific range.
Additional factors include individual corneal shape factors as well as an ability to wear [[contact lenses]]. A thorough consultation and examination using advanced computerised diagnostic instrumentation can easily determine if [[Orthokeratology]] is right for you.

Who is not a candidate for Ortho-k?

While ortho-k can be performed on practically anyone of any age who can insert a contact lens and follow lens care directions, it is generally not recommended for people with prescriptions above –10.00D of myopia, above +5.00D of Hyperopia or above -1.50D of with the rule astigmatism.
People with pupils that are larger than normal (>6mm in normal light) and those having irregular corneal astigmatism or any corneal disorder such as Keratoconus, are also generally eliminated as candidates.

How safe is Ortho-k?

Ortho-k is very safe when appropriately fitted and managed properly. Many people have been able to eliminate their dependence upon their glasses and standard [[contact lenses]] with no adverse effects or eye damage. 
Unlike surgical procedures like radial keratotomy (RK), photorefractive keratectomy (PRK), laser assisted in-situ keratomileusis ([[LASIK]]) and laser assisted sub-epithelial keratectomy (LASEK), the corneal tissue is not incised or vaporised by a laser which reduces the risk of permanent damage to the [[cornea]]. As with all contact lenses, proper lens care and handling must be performed to maintain eye health. The availability of state-of-the-art, high gas permeable materials and excellent lens care systems ensure excellent oxygen to the tissues of the eye further reducing the risk of eye infections.

Is Ortho-k permanent?

After treatment, maximum results are achieved and retainer Orrth-K lenses are worn to stabilise and maintain the new corneal shape. Failure to wear the retainer lens on an ongoing basis will result in a return to the pre-existing prescription. Retainer lenses will likely be prescribed for nightwear.

Can Ortho-k help children and teenagers?

Absolutely, orthokeratology is an ideal correction method for children and young adults.

Young boy studing with many booksMany children as they grow older will experience progressive myopia (nearsightedness) especialy children whose parents are myopic and children who spend most of their time indoors (reading, watching television and playing computer games) appear to be more at risk at developing Myopia . Myopia as a condition is becoming an epidemic and in countries like the United States the prevalence of myopia have show a dramatic increase in the last 30 years 1 and in some parts of Asia as much as 80% of the girls in high school are myopic2.

Research3 is showing that that there are methods to slow or prevent the progression of myopia (myopia control), but the actions work best when the child is younger. The Longitudinal Orthokeratology Research in Children (LORIC) study, published in 2005, tested if the wear of orthokeratology lenses could slow myopia progression, even if they couldn't permanently reverse the myopia already in place. The authors of the two-year pilot study concluded that corneal reshaping (orthokeratology) can have both a corrective and a control effect in childhood nearsightedness.

Myopic changes are generally permanent and can not be reversed with treatment. Treatment with orthokeratology should therefore be designed to prevent the development and progression and to do that requires eye examinations to start at a young age, approximately five years old for yearly exams.

Orthokeratology is not only a viable correction method for children but has the added advantage of slowing down or halting the progressive increase of myopia found in young children



1. Increased Prevalence of Myopia in the United States Between 1971-1972 and 1999-2004

2. Prevalence of myopia in local and international schools in Hong Kong

3. Myopia: its prevalence, origins and control

What are the risks of wearing the lenses overnight?

Studies have shown that wearing Rigid Gas Permeable (RGP) [[contact lenses]] overnight is safer than wearing conventional soft lenses continuously. The complications of wearing contact lenses include abrasions, corneal in-growth of vessels and ulcers.
The risks associated with wearing contact lenses overnight are slightly higher than wearing contact lenses only while awake and less than when wearing contact lenses continuously (day and night). Also, contact lenses cannot become “lost” behind the eye (this is anatomically impossible) and it is also rare for Ortho-k lenses to become decentred on the eye.

How long does it take for the process to stabilise and provide functional vision for the whole day?

It generally requires four to seven consecutive nights of wearing the Ortho-K lenses to achieve the desired result. It may take somewhat longer for those with [[hyperopia]] and higher degrees of [[myopia]].

Are Ortho-k lenses uncomfortable to wear overnight?

When initially inserting the orthokeratology lenses you will notice a feeling similar to a foreign body sensation in the eyes. The sensation is due to the eyelids moving over the edge of the lens when blinking. Fortunatly the eye adapts to this sensation over time.
Overnight wearing of the orthokeratology lenses is surprisingly comfortable. Most patients are unaware of their presence within a few minutes after inserting the lens due to orthokeratology lenses being worn during sleeping hours when no eyelid blinking is present.

Will I still have to wear glasses or contacts?

Once the desired correction level is obtained the final Ortho-K lenses act as retainer lenses to maintain that level. Regular glasses and [[contact lenses]] are not needed as the Ortho-k procedure provides clear, comfortable distance vision for the whole day.
However as with [[LASIK]] surgery, if you are [[presbyopic]], you will still require reading glasses to view near objects. During the initial treatment period, if unaided vision does not last a full day, you will be provided with soft disposable [[contact lenses]] to maintain normal distance vision until the procedure is completed.

Once the treatment phase is completed, how frequently will I need to wear the overnight retainer lenses?

Most people will need to wear the Ortho-K lenses six to seven consecutive nights per week to enjoy good, unaided vision for all of their waking hours. Patients with lesser degrees of [[myopia]] and [[hyperopia]] may find that wearing them every other night is satisfactory. However, this will have to be determined on an individual basis.

How much myopia can a person realistically expect to be able to reduce using Orthokeratology?

Internationally most [[Orthokeratology]] systems can correct up to -5.00D of [[myopia]]. Orthokeratology practitioners using the GOV Ortho-K system can comfortably achieve myopia corrections of up to -8.50D and regularly reduce as much as -10.00D of myopia. Lower amounts of myopia are normally easier and faster to reduce whereas the higher prescriptions take more skill and time to accomplish.

How about Ortho-k for astigmatism?

The amount of astigmatic reduction achievable with [[Orthokeratology]] will depend of the amount and the type of [[astigmatism]] present on the [[cornea]]. Normally -1.50D of ‘with the rule’ corneal astigmatism and -0.75D of ‘against the rule’ corneal astigmatism are considered the upper limits for astigmatic correction.

If you decide to return to wearing glasses, can vision be restored to its pre-treatment level?

The [[Orthokeratology]] procedure is completely reversible. After treatment is halted your eye's prescription will return to its pre-treatment amount of [[myopia]] or [[hyperopia]] in about 2 weeks. In order to provide good vision during this transition period, you will be refitted with gas-permeable- or disposable soft [[contact lenses]] while the corneas recover their pre-treatment shape.

If the patient becomes less nearsighted in later years, how will that be handled?

With Ortho-K, unlike laser refractive surgery that cannot be reversed, corneas can usually be remodelled to accommodate the change in prescription by changing the design of the retaining Orthokeratology lenses.