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Night Lenses

(nighttime MCT contact lens)
Frequently Asked Questions

Orthok / nighttime contact lens FAQs
Night lenses / Orthokeratology

1. Is there a difference between fitting orthokeratology lenses and regular contact lenses?

Fitting orthokeratology lenses requires a more precise testing process. Optometrists use corneal topography to map and create a 3D model of the eye's corneal shape to ensure the selection of the most suitable lens. During the trial fitting, the optometrist, parents, and wearer all assess and observe how well the lenses are being tolerated. Optometrists will also use a biomicroscope to record the fit between the orthokeratology lenses and the cornea to tailor the best lens.

Night lenses / Orthokeratology
Night lenses / Orthokeratology
Night lenses / Orthokeratology

Precision Optics Corneal Topographer

•  32 Rings 
•  102,000 Analysed Points
•  9600 Measurement Points 
•  Composite Mapping Coverage 0.25mm to 14mm
•  Extrapolated Data Out to 17mm
•  Power Range 10 - 100 Diopters

Night lenses / Orthokeratology

In the past, some people mistakenly thought that orthokeratology lenses reduced myopia by applying pressure through the lens's center. However, this is not the case. Ideally fitted orthokeratology lenses do not touch the central part of the cornea but use capillary action to move the myopia optics from the center to the periphery. As long as the fitting is accurate and the lens is properly cared for, using orthokeratology lenses will not pose a risk of damage to the cornea.

Night lenses / Orthokeratology
sMap3D orthok

3. How long can orthokeratology lenses last?


Orthokeratology lenses need to be replaced approximately every 12 months. Prolonged use of lenses can cause deformation, wear and tear, and scratches, which can affect their effectiveness.

4. Will the orthokeratology lenses fitting be affected by eye growth?


As time passes, the shape of the cornea will change, so wearing orthokeratology lenses requires regular eye exams. If the lens is no longer suitable, it needs to be replaced. Our correction service is charged annually, and if the lens needs to be replaced due to changes in the eye's prescription or corneal shape, there is no additional cost. This allows you to enjoy the correction service with peace of mind.

5. How long should orthokeratology lenses be worn at night? Do they need to be worn every day?


Orthokeratology lenses should be worn for 7-9 hours per night. They can be worn every night, but optometrists may arrange rest for one to two nights per week based on individual circumstances.

6. Orthokeratology lenses are theoretically safe, why have some cases occurred in the past where eyes were injured due to using the lenses?


Those cases were mainly due to not regularly checking the eyes, not using lenses as instructed by optometrists, using old lenses for a long time, and unnoticed lens defects. To protect your eyes, do not buy and use orthokeratology lenses on your own and use them under the supervision of an optometrist.

7. How long does it take to correct all myopia after using orthokeratology lenses?


Wearing orthokeratology lenses to sleep for one night already has a significant effect. Users with lower myopia degrees may only need 2-4 days to correct all myopia, while those with higher myopia may require 7-10 days or more to achieve the optimal effect.

high myopia Night lenses / Orthokeratology

8. Will myopia increase after using orthokeratology lenses?


Clinical studies have shown that wearing orthokeratology lenses at night, combined with sufficient outdoor activities during the day, can effectively slow down the progression of myopia. However, if there is a lack of outdoor activities during the day, myopia can still worsen even when wearing orthokeratology lenses, but it will be much slower than the group that does not use orthokeratology lenses.

9. Do I need to wear framed glasses during the day after using orthokeratology lenses?


In general, it is not necessary to wear glasses during the day after using orthokeratology lenses. However, if the astigmatism or myopia of vision is too high (such as over -6.00D), it may be necessary to use a pair of glasses with lower prescription to assist during the day. Studies have shown that even if some wearers still need to wear glasses with lower degrees during the day, it will not affect the effectiveness of myopia control.

10. What should I do if eyes feel uncomfortable after wearing orthokeratology lenses?


If your eyes feel uncomfortable after wearing the lenses, stop using them and return to our center to have your eyes and lenses checked. If the center is closed, give us a call and speak to one of our optometrists for advice.

11. Will myopia disappear after using orthokeratology lenses for a period of time?


The main purpose of orthokeratology lenses is to control myopia progression. When using the lenses, the myopia during the day will be reduced. Once you stop using the lenses, your original myopia will gradually rebound. Although there are individual cases where myopia has reduced after using orthokeratology lenses, the general outcome is that myopia remains at the original myopia or only slightly worsens.


12. What is the best age to start using orthokeratology lenses? What is the minimum age to use orthokeratology lenses?

Children aged seven and above as well as adults can generally use orthokeratology lenses, but it also depends on the wearer's ability to take care of the lenses.

13. Can orthokeratology lenses be used if someone has dry eyes?


In Western countries, orthokeratology lenses may be employed as an alternative to laser vision correction in cases where dry eye issues make the latter unsuitable. Our optometrist will assess your eye condition to determine the suitability of orthokeratology lenses for your needs.

14. What level of myopia is suitable for using orthokeratology lenses?


There is no limit to the level of myopia that can be corrected with orthokeratology lenses. However, if the astigmatism or myopia is too high (such as over -6.00 diopters), glasses may be needed during the day. Research has shown that even if myopia is not completely corrected, wearing glasses during the day will not affect the effectiveness of myopia control.

ultra high myopia OK lenses (ortho-k)
Our optometrists


More services

Eye Exam

Our Centre provides eye test for Adults and children from two and half years old. The eye test covers refractive errors, visual functions and eye health assessment.

​Progressive spectacle lenses + Multifocal contact lenses

We are well experienced  in progressive spectacle lenses and multifocal contact lenses fitting for management of presbyopia.

Myopia control & Orthokeratology


our centre also provide myopic control and orthokeratology service to kids and teenagers on indication.

Specialty contact lens services

In our center, we fit specialty contact lenses, such as rigid gas permeable (RGP) lenses, hybrid lenses and scleral lenses.

​Health Care Voucher

Our optometrists are appointed Health Care Service Providers of Health Care Voucher Scheme. Eligible Elderly may use Health Care Voucher for payment of eye examination and eyeglasses fee. For more information, you may contact us by telephone number 21530008 for eye examination booking.

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