ORTHOKERATOLOGY AND THE OPHTHALMIC ASSISTANT Elliott M. Rosengarten, OD

Transcription

1 ORTHOKERATOLOGY AND THE OPHTHALMIC ASSISTANT Elliott M. Rosengarten, OD This article and accompanying quiz are worth.5 JCAHPO Group A continuing education credit. CONTINUING EDUCATION CREDITS ARE SUBJECT TO CHANGE. Internet Articles are reviewed on a regular basis for content and amount of time needed to complete the article and quiz. We advise you to print the article and take the quiz within 30 days. Ample notice is provided when CE credits change - please check the Web site frequently for any updates and/or changes. We will accept articles for full credit within a 30-day time period when CE credits have changed or when an article has been removed from the Web site. INTRODUCTION This article will help the ophthalmic assistant become familiar with Orthokeratology (Ortho-K), a process by which nearsighted and/or astigmatic patients achieve clear vision during their waking hours by wearing contact lenses at night while they sleep. OBJECTIVES 1. Understanding this article will enable the assistant to: 2. Learn how Ortho-K works and its role in eye care 3. Counsel a patient about the benefits and limitations of Ortho-K 4. Teach a patient how to use Ortho-K lenses TEXT Orthokeratology (Ortho-K) is a nonsurgical, nonpermanent contact lens program used to reduce myopia and astigmatism. In essence, Ortho-K allows patients who are as nearsighted as 4D to 5D with up to 1.5D of astigmatism to go through a normal day with clear vision without wearing corrective lenses. A BIT OF HISTORY Ortho-K was discovered in the 1960 s when doctors observed patients who, after removing their hard plastic (PMMA) contact lenses, noticed that their uncorrected distance vision was improved. These contact lenses actually flattened the central

2 curvature of the cornea as well as made the curve more spherical. This reduced the nearsightedness and astigmatism for short periods of time. Rigid gas permeable contact lenses (RGP s) were developed in the early 1970 s. They were initially a combination of the old PMMA plastic and silicone and, unlike PMMA lenses, they let oxygen pass through the material itself. The health benefits of these new materials allowed for longer, more comfortable and safer wear. These new RGP Ortho-K lenses were still made in a similar fashion as standard RGP lenses to correct nearsightedness and astigmatism. HOW GAS PERMEABLE CONTACT LENSES ARE FITTED The curvature of the cornea is measured by a keratometer (cornea meter) or topographer (contour map). Standard RGP lenses are made so the inside or, base curve, of the contact aligns with the flattest curvature measurement of the cornea. There are two other curves closer to the edge of the lens that are flatter than the central base curve. This allows for an even distribution of the corneal tear film under the contact lens. It also provides good centration and movement of the contact lens on the cornea. When these factors occur, the patient has clear and comfortable vision. WHAT S SO DIFFERENT ABOUT TODAY S ORTHO-K LENSES? The first major advancement in Ortho-K occurred in the late 1980 s when an optometrist and a contact lens lab manufacturer created a lens called the Reverse Geometry Lens. Its curves were opposite of traditional lenses. The base curve was much flatter than the central cornea and the first peripheral curve was steeper. This allowed the central corneal tissue to be pushed away from the center of the cornea, providing a ripple effect, like dropping a pebble in the water. The displaced corneal tissue moved into the peripheral curve area of the contact. Reverse Geometry Lenses created a significantly shorter time to achieve good Ortho-K visual results. Instead of taking weeks to months to reduce nearsightedness, it only took days to a few weeks. Ortho-K became Accelerated Ortho-K.

3 With tremendous advancements in technology, significantly more oxygen could pass through the RGP s. The Food and Drug Administration (FDA) approved specific guidelines to allow RGP lenses to be worn for overnight wear in the 1990 s. Researchers found that wearing a Reverse Geometry Lens for a specific number of hours each day reduced nearsightedness. However, the same effect could be achieved by wearing the lenses only while sleeping from six to eight hours per night. Some advantages of wearing RGP s only overnight were that the endpoint of clear vision without glasses could be achieved much sooner than daytime wear and that lens awareness and frequent lubrication were greatly reduced. Reverse Geometry Lenses made from highly oxygen permeable materials made the concept of overnight Accelerated Ortho-K a natural. This has been the method of choice for Ortho-K for several years and the FDA gave its approval for this use of these contact lenses in the spring of ORTHOKERATOLOGY VS. REFRACTIVE SURGERY Patients may choose to undergo Ortho-K for various reasons. It is ideal for children for whom control of myopia progression is desired. Athletes, pilots, police officers and others seek clear vision without daytime correction. For economic reasons, Ortho-K may be preferred as it usually costs about ½ of LASIK. Those who are apprehensive about surgery on their eyes find Ortho-K to be a viable option as many who desire a refractive procedure already wear contact lenses. The visual outcome may be fine tuned with Ortho-K. Less than ideal results such as flare around headlights at night or blurred vision may be improved changing the centration of the lens or one or more of its curves. Finally, Ortho-K is fully reversible. If the patient is unhappy with the visual result, they may reverse it simply by discontinuing overnight wear. Refractive surgery has been available in the United States since the late 1970 s with Radial Keratotomy and has progressed to LASIK. Refractive surgery also involves flattening the central cornea to reduce nearsightedness just like Ortho-K. LASIK can correct up to about 10 diopters of nearsightedness, whereas Ortho-K reduces up to 4-5

4 diopters. As technology has improved, precision and accuracy has also improved. The one factor, though, that cannot be predicted is the healing of the patient s cornea. A 3%-5% complication rate has been reported, with complications ranging from blurred vision to dry eye syndrome to fluctuating vision. LASIK offers a permanent procedure to patients who want to improve their vision. This permanence and the ability to remove much greater degrees of myopia than Ortho-K make LASIK very popular. Neither LASIK nor Ortho-K provides both clear distance and near vision when a patient is presbyopic, unless monovision (one eye for distance and one for near) is used. A 25-year-old woman having refractive surgery doesn t think about a problem that she won t experience for another 20 years. So when she cannot read near print at age 45, she is back in a corrective lens. A presbyopic Ortho-K patient can modify the wearing schedule or the lens design or both in one eye, allowing it to become somewhat nearsighted. If well tolerated by the patient, she would then need no daytime corrective lenses. The bottom line in deciding between Ortho-K and refractive surgery are patient goals, expectations and what is reality. Only a truly informed patient can choose which is best for him or her. THE ORTHO-K PROCESS A comprehensive eye examination is given to determine if a patient is a good candidate for Ortho-K. In addition to the appropriate refractive error of no more than 5 diopters of myopia and 1.5, the exam uncovers any corneal irregularity as well as dry eye, blepharitis or ocular allergy. Any of these problems could jeopardize the efficacy of Ortho-K. Patients wearing soft contact lenses can be evaluated without discontinuing contact lens wear, as corneal thickness isn t a factor as it is in refractive surgery. However, patients wearing RGP lenses must remove them for at least one month prior to the evaluation. If the patient is a good candidate, then a discussion about Ortho-K allows the patient to fully understand the process. Once all questions are answered, the informed consent is discussed and signed. The initial Ortho-K lenses are then ordered. Among the leading contact lens companies specializing in Ortho-K lenses are Contex, Euclid Systems, ABBA and Gelflex Laboratories. The lenses are slightly larger than conventional RGP lenses and are typically fitted about X diopters flatter centrally and 3 diopters steeper in

5 the outer curve. A minimal amount of farsighted power is incorporated in the lenses, allowing clear vision through the lenses if the patient awakens in the middle of the night. The dispensing visit consists of patient instruction of insertion, removal and lens care. The lenses are evaluated on the eyes with the slit lamp. Excellent centration is the most important factor in fitting Ortho-K lenses. The patient is instructed to insert the lenses immediately prior to going to sleep and lubricating drops are instilled. Any lens awareness should be minimal with the closed eyelids. Upon awakening the lens lubricant is used and the lenses are cleaned, rinsed and stored in the lens case (with the exception of the first morning when the lenses are worn into the doctor s office). The following morning, the lenses and the cornea are evaluated with the slit lamp. The lenses should still be centered and should not have tightened. There should be minimal corneal staining. After lens removal, uncorrected visual acuity, topography and refraction are done. Typically, the reduction in nearsightedness is anywhere from one to 2 ½ diopters after just one night of wear. Any remaining refractive error can be corrected using disposable soft contacts. The patient is seen again sometime in the next four to seven days. Instruct the patient to always bring the lenses into the office should it become necessary to evaluate the fit. Follow up visits usually occur every four to seven days until good acuity is achieved without significant refractive error. The visits are then extended to monthly and every three months. Typically, only one or two pairs of lenses are needed to achieve the desired results. The final pair of lenses is used as the retainer pair. The desired results are usually achieved within the first two to four weeks following the dispensing visit. CASE REPORT The following case report illustrates the manner in which Ortho-K can significantly improve a patient s vision in a safe, noninvasive way. E.M. is a nine-year-old male whose parents are moderately nearsighted. He is active in athletics and wants to be free of glasses and contacts during the day.

6 Initial findings: Uncorrected VA OD 20/100 Refraction OD 2.25 DS OS 20/100 OS 2.00 DS Topography OD 44.75/45.12 OS 45.12/45.25

7 Caption: Excellent topographic maps for Ortho-K. First morning following overnight wear: Uncorrected VA OD 20/30- Refraction OD 1.00 DS OS 20/25 OS 0.75DS Topography OD 44.87/45.00 OS 44.87/44.87

8

9 Caption: The Reverse Geometry Lens displaces the central corneal tissue. This tissue migrates into the mid peripheral curve in the contact. The orange ring represents the added tissue in the mid peripheral curve. One week follow up: Uncorrected VA OD 20/20 Refraction OD 0.25 DS OS 20/20 OS 0.25DS Topography OD 43.75/44.37 OS 44.50/44.50 The one month follow up is similar to the one week visit. Seven month follow up: Uncorrected VA OD 20/20 Refraction OD 0.25 DS OS 20/20 OS PLANO Topography OD 44.25/44.37 OS 44.50/45.00

10

11 The orange ring remains the key to a successful Ortho-K patient. SUMMARY Ortho-K is a nonsurgical, nonpermanent method of correcting nearsightedness and astigmatism. Continued development of contact lens materials and manufacturing have made Ortho-K a viable alternative to refractive surgery. The ophthalmic assistant should be familiar with this increasingly popular contact lens modality. AUTHOR Elliott M. Rosengarten, O.D. Private Practice, Louisville, Kentucky. REFERENCES Winkler, Todd D. and Kame, Rodger T., Orthokeratology Handbook, Butterworth- Heinemann, Boston, Waking Up to Modern Ortho-K, Optometric Management, September 1999.

12 Quiz ORTHOKERATOLOGY AND THE OPHTHALMIC ASSISTANT This article and accompanying quiz are worth.5 JCAHPO Group A continuing education credit. 1. Ortho-K removes about what maximum amount of myopia? a. 1-2 D b. 2-3 D c. 3-4 D d. 4-5 D 2. Ortho-K was discovered in the: a s b s c s d s 3. What material was originally used for contact lenses? a. Soft b. PMMA c. Gas Permeable d. polycarbonate 4. Gas Permeable contact lenses were developed in the: a s b s c s d s 5. The best instrument to evaluate the contour of the cornea is a: a. lensometer b. slit lamp c. topographer d. tonometer 6. Regular RGP lenses are fit in alignment with which corneal curve? a. flattest b. steepest c. oblique d. tangent 7. The lens design developed in the 1980 s that revolutionized Ortho-K is called the: a. Backwards Lens b. Toric Lens c. Reverse Geometry Lens d. Spherical Lens

13 8. The FDA approved overnight wear of these lenses in: a b c d Current Ortho-K lenses have which curvature features? a. all curves the same b. flat central curve and steep mid peripheral curve c. different curves 90 degrees apart d. steep central curve and flat mid peripheral curve 10. Patients who could benefit from Ortho-K are: a. children b. athletes c. pilots d. all of the above 11. Accelerated Ortho-K takes how long to achieve the desired VA? a. a few minutes b. a few days to two weeks c. years d. never, because it doesn t work 12. One advantage of LASIK over Ortho-K is: a. it can reduce more myopia b. it is inexpensive c. it is reversible d. it can be done on anyone 13. Which factor is most essential in a successful Ortho-K fit? a. lens diameter b. lens material c. lens material d. lens centration 14. What topography pattern is desired in a good Ortho-K result? a. the same color throughout the map b. a circular band of steepening in the mid periphery c. a band of one color horizontally and another vertically 15. Ortho-K lenses are worn into the office on which visit? a. first morning after overnight wear b. one week visit c. one month visit d. they are never worn into the office

14 ORTHOKERATOLOGY AND THE OPHTHALMIC ASSISTANT COMPLIMENTARY QUIZ ANSWER SHEET This quiz is worth.5 JCAHPO Group A continuing education credits You must complete the enclosed quiz on your own and may not seek assistance from other individuals. You may, however, seek assistance from other individuals for clarification and understanding of the article content. Failure to comply with this policy may result in the revocation of credit. Name ATPO ID # Home Address City / State / Zip Home Phone Address Work Phone Signature ALLOW UP TO TWO (2) WEEKS FOR PROCESSING ATPO Member Complimentary* OR ATPO Member Complimentary Retest* All articles are also available for purchase at Place your answers to each question in the appropriate space adjacent to the question number A total of 75% or more correct is a passing score. ATPO is not responsible for Answer Sheets and Evaluation Forms not received at the ATPO offices. I attest that I have completed this quiz on my own. (SIGNATURE) CONTINUING EDUCATION CREDITS ARE SUBJECT TO CHANGE. Articles are reviewed on a regular basis for content and amount of time needed to complete the article and quiz. We advise you to print the article and take the quiz within 30 days. Ample notice is provided when CE credits change - please check the Web site frequently for any updates and/or changes. We will accept articles for full credit within a 30-day time period when CE credits have changed or when an article has been removed from the Web site. Return completed answer sheet and evaluation to: ATPO 2025 Woodlane Drive St. Paul, MN Fax: (651)

15 CE EVALUATION ORTHOKERATOLOGY & THE OPHTHALMIC ASSISTANT Please read each question carefully. Your feedback is important to us. Thank you! 1. How long have you been employed in the field of ophthalmology? years 2. This written article was designed at a level right for me. (circle one) YES NO 3. Please read the following statements. Then, circle the number corresponding to the degree to which you agree with each statement. Statement a. The material was organized and presented in a clear and efficient way. Strongly Agree Agree Disagree Strongly Disagree Not Applicable b. The information will be useful/relevant to me c. The material was presented at a level appropriate to my background and level d. Overall, I was satisfied with the article What part of the article was most useful to you? 5. What part of the article was least useful to you? 6. What suggestions do you have for improving this article? Thank you for completing this article evaluation! ATPO values your feedback. Please return your evaluation form with the completed quiz. ATPO 2025 Woodlane Drive St. Paul, MN Fax: (651)