Orthokeratology (Shift Lenses)
Ortho-K lenses, also called Shift Lenses, are an amazing bit of optometry technology. In fact, they are one of the most comfortable and unobtrusive contact lens solutions available—because you don’t wear them during the day! They do their work while you sleep, shape-shifting your cornea to correct your vision.
Shift your perspective to perfect vision with these fantastic lenses! You can fill out the contact form below to find out whether Ortho-K/Shift lenses are right for you.
For further information, visit shiftlenses.co.nz
There is a good chance that you will still be able to succeed with Shift lenses Ortho-K. Many contact lens wearers discontinue wear because of dryness or discomfort. These are usually not an issue with Shift lenses Ortho-K because the lenses are only worn while you sleep. Also, because your eyes are not wearing lenses while awake, they receive more oxygen to help maintain optimum eye health.
Shift lenses are a type of orthokeratology lens. These are designed specifically for you by your Optometrist and provide a clear range of vision for a wide variety of patients.
The safety and effectiveness of modern Ortho-K has been demonstrated by independent studies at University Research Departments in Australia and around the World. As with all contact lenses, good hygiene and regular check-ups are important.
Between 1997 and 2007 there were 123 reported cases globally of microbial keratitis associated with orthokeratology use (1). In 2007 the Singapore National Eye Centre presented a five patient case series suggesting an association of pseudomonas aeruginosa infection with overnight orthokeratology lens use(2). In 2008 the American Academy of Ophthalmology reviewed seventy-five articles investigating the safety of orthokeratology and concluded that ‘‘future research should be directed at assessing the rate of infectious keratitis among overnight orthokeratology users and whether the rate varies by age”(3). In 2010 a Canadian study presented three cases of keratitis related to overnight orthokeratology lens use(4). Choo et al studied pseudomonas and infection rates on cat epithelia and compared alignment fit and orthokeratology lenses. In order to elicit a infectious response with overnight orthokeratology lens wear the lenses had to be soaked in pseudomonas and a corneal abrasion present, whereas lenses soaked and worn in the absence of corneal trauma, showed no significant increase in risk(5). Bullimore et al concluded that the overall estimated incidence of microbial keratitis is 7.7 per 10,000 years of wear (95% CI = 0.9 to 27.8) whilst the estimated incidence of microbial keratitis is nearly twice as high (13.9 per 10,000 patient-years 95% CI = 1.7 to 50.4) in children. This contrasts to adults, where the estimated incidence of microbial keratitis is 0 per 10,000 patient-years (95% CI = 0 to 31.7) The fact that the CIs for the rates estimated overlap should not be interpreted as evidence of no difference.(6). Key factors in complications include poor patient knowledge of cleaning systems and hygiene.
It has been suggested that corneal iron lines may be caused by hyperopic orthokeratology corrections over +3.50, with the current proposed mechanism being microepithelial trauma or irregular folding of the epithelium from irregular pooling of tear film beneath the contact lenses(7). Other case series of iron line formation have concluded that this is a benign finding with no long term effect on visual acuity and physiology(8,9). The research is yet to report on their resolution following cessation of orthokeratology lens wear.
- Koffler BH, Sears JJ. Myopia Control in Children through Refractive Therapy Gas Permeable Contact Lenses: Is it for Real? American Journal of Ophthalmology. 2013 Nov 30;156(6):1076–10e1
- Chee EWL, Li L, Tan D. Orthokeratology-related infectious keratitis: a case series. Eye & Contact Lens: Science & Clinical Practice. 2007 Sep;33(5):261–3.
- Van Meter WS, Musch DC, Jacobs DS, Kaufman SC, Reinhart WJ, Udell IJ. Safety of Overnight Orthokeratology for Myopia. Ophthalmology. 2008 Dec;115(12):2301–1.
- Yepes N. Infectious Keratitis After Overnight Orthokeratology in Canada. 2010 Oct 19;:1–4.
- Choo JD, Holden BA, Papas EB, Willcox MDP. Adhesion of Pseudomonas aeruginosa to orthokeratology and alignment lenses. Optom Vis Sci. 2009 Feb;86(2):93–7.
- Bullimore MA, Sinnott LT, Jones-Jordan LA. The risk of microbial keratitis with overnight corneal reshaping lenses. Optom Vis Sci. 2013 Sep;90(9):937–44.
- Kirkwood BJ, Rees IH. Central corneal iron line arising from hyperopic orthokeratology. Clin Exp Optom. 2011 Jul;94(4):376–9.
- Rah MJ, Barr JT, Bailey MD. Corneal pigmentation in overnight orthokeratology: a case series. Optometry. 2002 Jul;73(7):425–34.
- Liang JY-B, Chou P-I, Wu R, Lee Y-M. Corneal iron ring associated with orthokeratology. Journal of Cataract & Refractive Surgery. 2003 Mar;29(3):624–6.
Until relatively recently there has been no scientifically proven way of reducing the progression (worsening) of myopia (short-sightedness). It has been long understood that genetics and environment play a role, but the mechanism of myopia progression has now had some clarification in research conducted internationally. It has been shown that where the light focuses in the periphery (side) of the retina has a strong influence on the progression of myopia. Studies show that Ortho-k is the best option for myopia control treatment with 50% or greater potential for reduction. For more on myopia control click here. If you are a parent of a short sighted child then make sure you take the self test today to assess your childs risk.
When wearing spectacles or traditional contact lenses, the image is clear on the central part of the retina and blurry in the outer parts (or periphery) of the retina. After Ortho-K or corneal moulding, the image is now clear in the periphery of the retina. Creating this situation for a short sighted patient has shown to be a “dimmer” switch for myopia progression. In other words Ortho-k creates a condition that can reduce the progression of myopia.
George Jessen first announced the concept of “Orthofocus” in 1964. Many manufacturers have coined terms for it such as CRT (Corneal Refractive Therapy), VST (Vision Shaping Therapy), Dreamlens, OK, Emerald, GOV and Orthokeratology. Since then technology has moved this procedure into the 21st century more so in the last 15 years, and this is mainly due to manufacture technique, research into safety and infection rates, and standards of practice in both Australia and New Zealand set about by the Orthokeratology Society for Oceania, this is an concept which is relatively new to New Zealand in many respects but old to the world.
Ortho-K works by gently remolding the front surface / window of the eye called the cornea. It does this by using the tears underneath a specially designed mold or lens. The lens itself creates an shape like a dental retainer and it is the sucking forces of the tears which actually do all of the work. The lens itself does not physically press on the eye in any way.