Overnight Corneal Reshaping in 2014 and Beyond
A review of what we currently know about corneal reshaping and what the future holds for the modality.
BY MICHAEL J. LIPSON, OD, FAAO
Orthokeratology, or corneal reshaping, has been practiced in some form in the United States since the 1970s. Overnight corneal reshaping (OCR) commenced in the early 1990s and received United States Food and Drug Administration (FDA) approval in 2002. Since that time, we have learned much from clinical experience in addition to laboratory and clinical research about the process.
This article discusses what we currently know about OCR and in what direction the modality may be heading in the future.
Patients Love It
Patients wear OCR lenses only while sleeping, and they are always impressed when they can see well after removing their OCR lenses in the morning. Most myopic patients report that it’s an amazing feeling to perform all of their daily activities without having to use glasses or contact lenses. It’s a completely different routine for patients to apply their lenses before they go to sleep and remove them upon waking; but, many patients have described a new sense of confidence and a feeling of independence because no daytime vision correction is needed.
In addition, previous soft lens wearers report experiencing less dry eye symptoms during the day with no lenses as compared to the dry feelings that they experienced while wearing their soft contact lenses. In a study of patients who wore both OCR and soft contact lenses, 70% preferred OCR (Lipson et al, 2005).
Furthermore, this study and others have reported improved vision-related quality of life (VR-QOL) in patients using OCR compared to those using soft lenses or glasses (Santolaria et al, 2013; Rah et al, 2004; Berntsen et al, 2006; Walline et al, 2007). VR-QOL encompasses quality of vision, vision in various conditions, activity restrictions, self-confidence, worry about vision, vision fluctuations, glare, symptoms of dryness or discomfort, and overall satisfaction with vision. So, these studies indicate that patients corrected with OCR tend to feel more confident about their vision and their ability to perform various activities.
Practitioners Have Been Slow to Adopt It
Even though OCR has been FDA-approved in the United States for almost 12 years, there are still only a small number of eyecare practitioners promoting and prescribing it. Certification is required in the United States to prescribe OCR lenses. Although no accurate data is available, estimates indicate that while 6,000 to 8,000 U.S. practitioners are certified to fit OCR lenses, only about 400 fit one or more patients per week (Sicari et al, 2013).
Some practitioners who are not familiar with GP lenses may shy away from OCR because it involves specially designed GP lenses. In addition, practitioners who are not familiar with changing the cornea in a controlled way may not feel comfortable doing so.
Practitioners can learn more about the OCR process in many ways: articles such as this one; webinars, classes/lectures, and wet laboratories at local and national meetings; specialty workshops; by communicating with consultants from the various manufacturers; or by talking to an experienced practitioner.
How It Works
The corneal changes created by wearing OCR lenses are not mechanical; rather, they are created via fluid forces exerted under the various curves of the posterior lens surface. Several studies have demonstrated that the changes created with OCR are solely epithelial. It is not a structural “bending” of the cornea, but rather a redistribution and relative thinning/thickening of the corneal epithelial cell layer (Hague et al, 2004; Alharbi and Swarbrick, 2003; Tsukiyama et al, 2008). The resulting changes in corneal shape are evident when analyzing pre- and post-treatment corneal topography (Figure 1). The effects of OCR are temporary, but can provide excellent visual acuity for 12 to 48 hours following lens removal. With experience, manipulation of the various curves of the posterior surface allows for a very controlled and predictable change in the corneal topography that results in improved unaided visual acuity (Haque et al, 2004; Swarbrick et al, 1998).
Figure 1. Pre/post OCR: tangential difference map (top), Pre/post OCR right and left eyes, axial display map (bottom).
Additionally, studies have shown that the effects of OCR are temporary and completely reversible (Barr et al, 2004; Soni et al, 2004; Kobayashi et al, 2008). When patients discontinue OCR, their refraction and topography return to baseline. This factor has been viewed as both a limitation and an advantage of OCR. As a limitation, it requires patients to wear lenses on an ongoing basis for as long as they desire to use OCR. But the advantage is that if they ever choose to discontinue the process, they are able to return to their original refractive and topographic condition.
OCR Is Safe and Effective
Safety in contact lens wear of any type is always a concern, especially in children. A retrospective study of 300 children and adults who wore Paragon CRT (Paragon Vision Sciences) lenses over a four-and-a-half year period was conducted at the University of Michigan (Lipson, 2008). During the study period, three minor adverse events occurred that required medical treatment. They involved central epithelial defects resulting from debris trapped under the lens. Each of these cases was treated and showed no loss of best-corrected visual acuity at the follow-up evaluation. One case resulted in a small scar, and each of these patients returned to OCR and continued to wear OCR lenses without further complication.
The potential for complications with OCR lenses does exist, but it is minimal provided that: 1) patients are compliant with lens care, cleaning, and disinfecting procedures, 2) providers and patients are diligent in performing regular follow-up visits, 3) adequate lubricants are used, and 4) lenses are replaced on a regular basis. A collaboration of worldwide experts summarized their findings on corneal reshaping by stating, “Risk of severe complications with corneal reshaping contact lenses is present, but may be no different than with other overnight wear contact lens modalities” (Walline et al, 2005).
A very recently published study on OCR with more than 1,300 patients representing 2,593 patient-years of wear reported only two events of microbial keratitis (MK). This equates to 7.7 MK events per 10,000 years of wear (Bullimore et al, 2013). As a reference, the incidence of MK events with overnight wear of silicone hydrogel lenses has been reported as 25.4 per 10,000 wearers (Stapleton et al, 2008; Dart et al, 2008).
OCR Seems to Slow Myopia Progression
In addition to enjoying clear vision with no correction during waking hours, children using OCR may show significantly slowed myopia progression. Although the perfect study on OCR’s effects on myopia progression has yet to be performed, a number of studies show reduced myopia progression in children wearing OCR lenses compared to those using single vision spectacles, multifocal spectacles, soft lenses, or single vision GP lenses (Cho and Cheung, 2012; Downie and Lowe, 2013; Kakita et al, 2011; Walline et al, 2004; and others. Full list available at www.clspectrum.com/references.asp). These studies, performed for up to five years with children during their growth years, show a 50% to 70% reduction in the rate of myopia increase and a corresponding reduction in the rate of axial length increase. Some subjects involved in these studies showed no progression in myopia or axial length during the study period.
The current theory as to why OCR works so well at slowing myopia progression relates to the way in which it changes the peripheral refraction. When myopic patients are corrected with spectacles or soft lenses, light is focused very precisely at the fovea to provide optimal central visual acuity; however, these patients show that peripherally, away from the fovea, objective refraction exhibits relative hyperopia (light focused behind the retina). In contrast, while OCR patients show good foveal focus, the peripheral refraction exhibits relative myopia (light focused in front of the retina) (Charman et al, 2006; Queiros et al, 2010; Mutti et al, 2011) (Figure 2). This relative peripheral myopia has been shown to stop/slow the stimulation of the eye to increase in axial length.
Figure 2. OCR is believed to help slow myopia progression by creating peripheral myopic defocus.
Myopic patients, especially those who have high myopia (>–6.00D), have a higher incidence of serious eye problems throughout their life including retinal tears, retinal detachments, glaucoma, cataracts, macular degeneration, and other peripheral retinal degenerations. If we are able to reduce the amount of increased axial length during growth years, we should see a reduction in these eye complications later in life.
Fitting and Management
Office policies and procedures require planning and careful thought with regard to managing OCR patients. First, and most important, is staff education and enthusiasm. All office staff should be well-versed in discussing OCR with patients, creating excitement about it, and identifying who may be good potential candidates. It’s ideal to have staff members become OCR users to experience the modality firsthand.
Second, it’s very helpful to create an informed consent, or “fitting agreement,” that spells out the services that you will be providing to patients as well as what is expected of them. This includes items such as risks and benefits, necessity for compliance in wearing and care, follow-up schedule, emergency contact procedures, what is included in the initial costs, ongoing costs, replacement lens costs, and other office policies. Patients are much happier and are more successful long-term when they know what to expect.
The next consideration involves procedures and equipment. Corneal topography is a requirement for OCR. This technology has become a standard of care in most contact lens practices, and it is absolutely essential to use with OCR to establish baseline topographic characteristics and to monitor treatment quality and centration.
Next, you need to establish what OCR lens designs to prescribe. Some designs use a completely empirical fitting philosophy, some use diagnostic/dispensing systems, some use traditional diagnostic lens fitting, and others are based totally on topography. Figure 3 shows the fluorescein pattern of a well-fit OCR lens. The system you use will dictate whether you are able to dispense lenses at the time of initial fitting or whether each lens is custom-ordered to be dispensed at a subsequent visit. Each system has pros and cons that you should discuss in detail with experienced practitioners and/or laboratory consultants to help you decide which is best for your office.
Figure 3. Well-centered fluorescein pattern for OCR.
Regarding patient flow, especially with your first few OCR patients, be sure to schedule additional time for new OCR patients. Some offices have prepared for this by designating certain time slots or days just for new OCR patients.
Finally, remember that OCR is a process, not just a lens. Patients undergoing the process of OCR must be committed to regular wear of lenses (many cases require wear every night), careful hygiene and lens care, and compliance in follow-up care.
OCR Will Become More Popular
The popularity of OCR has been slowly growing among practitioners and patients since it received FDA approval 12 years ago. Its growth has resulted almost entirely from word-of-mouth referrals from enthusiastic patients and from promotion within the offices of practitioners who enjoy prescribing OCR.
In the next few years, I believe that more practitioners will start prescribing OCR for a variety of reasons. First, it’s a new service that practitioners can provide to expand their patient base and to provide an additional stream of income. It’s a very customized and personal type of service that is generally not offered by mass merchandisers and commercial eye care. Second, OCR was previously not taught in optometry school, but it is now being introduced to optometry students. As a result, it may capture even more attention as a “standard” service in practice rather than as a “sub-specialty” service. Historically, the same scenario occurred with general contact lenses in optometry school and in practice. Contact lens services have come a long way in 40 years and are now expected to be offered in most eyecare practices. Third, because of the expertise required of practitioners in combination with the follow-up care required, the higher fees associated with OCR can become a significant profit center for eyecare practices. It is significant to note that fees for OCR are not insurance-dependent.
An additional benefit for your practice is that because OCR patients come in regularly, they become a part of your office family.
Of late, OCR is gaining more attention at educational meetings and has a very vibrant national and international organization. The Orthokeratology Academy of America (OAA), soon to become the American Academy of Orthokeratology and Myopia Control (AAOMC) is the U.S. branch of the International Orthokeratology Academy (IAO).
Finally, increased public awareness of OCR and its myopia control potential will create an increasing demand for the procedure.
The Future of OCR
OCR will continue to improve through new lens design capabilities, new materials, innovative manufacturing, and improved diagnostic technology. New designs may include customized zone sizes, increased diameters, toric and/or aspheric curves, and variable thickness profiles. New materials may feature higher oxygen permeability or greater bacterial and deposit resistance. Manufacturing capabilities may allow for almost unlimited curvature profiles. Diagnostic improvements may come in the form of combining topography and optical coherence tomography technology into one test. In addition, measuring peripheral refraction may become a standard of care relative to designing lenses that produce ideal control of myopia progression.
In a different vein, we may see the development of lubricating and conditioning solutions that make OCR more comfortable for patients and even safer than it already is. Also, OCR, in combination with the use of supplemental pharmaceuticals (oral or topical) or surgical corneal procedures, such as corneal cross-linking, may enhance the potential for higher amounts of refractive change or longer lasting effects of OCR.
In its present form, OCR is a safe and effective alternative to glasses, daytime contact lenses, and laser-assisted in situ keratomileusis (LASIK) to correct refractive error. OCR patients perceive an improved VR-QOL, mainly due to a feeling of independence from the necessity of daytime vision correction options. OCR’s additional feature of myopia control as observed in practice and reported in clinical studies will continue to attract interest among parents of myopic children who are looking for a way to slow or stop the rapid progression of myopia. In addition, myopia control will continue to be a “hot button” issue for health care administrators looking for ways to avoid long-term costs associated with complications of high myopia.
During the process of OCR, children, particularly those involved in sports, can enjoy the ability to function without worrying about their vision correction. Adults undergoing OCR can enjoy fewer dry eye symptoms compared to soft lens wearers in addition to less activity restrictions due to a need for vision correction.