Orthokeratology in Moderate Myopia: A Study of Predictability and Safety
Purpose: Literature is relatively silent on safety profile and predictability of orthokeratology lenses in terms of myopia correction and prevention of further progression, especially in semi-tropical countries; this study was designed to fill this gap.
Methods: This prospective, intervention case series enrolled 30 eyes of 30 patients with myopia up to –5.5 diopters (D). Patients were randomized into two groups of 15 each; the study group was prescribed overnight orthokeratology (OK) lenses, while the control group used daily wear conventional soft contact lenses. Follow-up examinations were performed after 1 h and 6 h, and then at 1, 7, 15, 30 days, and 4 months post lens wear. Uncorrected visual acuity (UCVA), contrast sensitivity, keratometry, central corneal thickness (CCT), and tear film break up time (TBUT) were evaluated at each follow-up examination.
Results: All patients attained a visual acuity of 0.00 Logarithm of the Minimum Angle of Resolution (logMAR) after one week of lens use, which was maintained throughout the study period. While patients allotted to the study group had a gain of 8.1 Snellen lines (UCVA), those in the control group gained 8.9 lines (BCVA) at the end of follow-up period. In the OK group, cornea showed a flattening of 0.8 D (mean keratometry) after single overnight usage of OK lens and overall flattening of 1.2 D compared to baseline, at the end of four months. The change in contrast sensitivity, corneal endothelial specular count, axial length and tear film status was not significant in either group.
Conclusion: Orthokeratology is an effective and safe modality to correct moderate myopia in motivated young adults. No side effects were encountered after a short-term follow-up in participants who resided in semi-tropical environments.
Contact Lens, Overnight Wear, Orthokeratology, Moderate Myopia, Semi-tropical Environments
1. Kerns RL Research in orthokeratology. Part I: Introduction and background. J Am Optom Assoc 1976;47:1047–1051.
2. Wesley N, Jessen G. Advanced techniques in contact lens fitting. 2nd ed. Chicago, IL: Contact Lens Publishing Company; 1960:1–67.
3. Jessen G. Orthofocus techniques. Conctacta 1962;6:200– 204.
4. Kerns RL. Research in orthokeratology. Part VIII. Results, conclusions and discussion of techniques. J Am Optom Assoc 1978;49:308–314.
5. Coon LJ. Orthokeratology. Part II: evaluating the Tabb method. J Am Optom Assoc 1984;55:409–418.
6. Polse KA, Brand RJ, Schwalbe JS, Vastine DW, Keener RJ. The Berkeley orthokeratology study, part II: efficacy and duration. Am J Optom Physiol Optics 1983;60:187–198.
7. Wlodyga RJ, Bryla C. Corneal molding: the easy way. Contact Lens Spectrum 1989;4:58–65.
8. Grant SC, May CH. Orthokeratology: a therapeutic approach contact lens procedures. Contacto 1970;14:3.
9. Swarbrick HA, Wong G, O’Leary DJ. Corneal response to orthokeratology. Optom Vis Sci 1998;75(11): 791-9.
10. Yoon YM, Kim MK, Lee JL. Change of corneal parameters after removing reverse geometry lens in moderate degree myopia. J Korean Ophthalmol Soc 2005;46:1478–1485.
11. Kerns RL. Research in orthokeratology. Part III: results and observations. J Am Optom Assoc 1976;47:1505–1515.
12. Cariello AJ, Passos RM, Yu MC, Hofling-Lima AL. Microbial keratitis at a referral center in Brazil. Int Ophthalmol 2011;31:197–204.
13. Dos Santos DL, Kwitko S, Marinho DR, Araújo BS, Locatelli CI, Rott MB. Acanthamoeba keratitis in Porto Alegre (southern Brazil): 28 cases and risk factors. Parasitol Res 2018;117:747–750.
14. Mountford J, Pesudovs K. An analysis of the astigmatic changes induced by accelerated orthokeratology. Clin Exp Optom 2000;85:284–293.
15. Swarbrick HA. A possible aetiology for RGP lens binding (adherence). Int Contact/Lens Clinic 1998;15:13–19.
16. Lee YC, Wang JH, Chiu CJ. Effect of orthokeratology on myopia progression: twelve-year results of a retrospective cohort study. BMC Ophthalmol 2017;17:243.
17. Cho P, Cheung SW, Edwards M. Practice of orthokeratology by a group of contact lens practitioners in Hong Kong, Part 2. Clin Exp Optom 2002;86:42–46.
18. Swarbrick HA, Alharbi A. The effects of overnight orthokeratology lens wear on corneal thickness. Invest Ophthalmol Vis Sci 2003;44:2518–2523.
19. Soni P, Nguyen T. Corneal parameter, anterior corneal curvature, posterior corneal curvature or corneal thickness, acute changes with reverse geometry orthokeratology lenses. J Ocul Pharmacol Ther 2002;46:221–224.
20. Luo M, Ma S, Liang N. Clinical efficacy of toric orthokeratology in myopic adolescent with moderate to high astigmatism. Eye Sci 2014;29:209–213.
21. Lui WO, Edwards MH. Orthokeratology in low myopia. Part 2: corneal topographic changes and safety over 100 days. Cont Lens Anterior Eye 2000;23:90–99.
22. Santolaria-Sanz E, Cerviño A, González-Méijome JM. Corneal aberrations, contrast sensitivity, and light distortion in orthokeratology patients: 1-year results. J Ophthalmol 2016;2016:8453462.
23. Tang W. The relationship between corneal topography and visual performance. J Am Optom Assoc 1999;24:312–318.
24. Sun Y, Wang L, Gao J, Yang M, Zhao Q. Influence of overnight orthokeratology on corneal surface shape and optical quality. J Ophthalmol 2017;2017:3279821.
25. Kam KW, Yung W, Li GKH, Chen LJ, Young AL. Infectious keratitis and orthokeratology lens use: a systematic review. Infection 2017;45:727–735.
26. Swarbrick H. Overnight orthokeratology and the risk of microbial keratitis. Eye Contact Lens 2005;31:201–208.
27. Watt K, Swarbrick H. Trends in microbial keratitis associated with orthokeratology. Eye Contact Lens 2007;33:373–377.
28. Tian M, Ma P, Mu G. Prospective cohort comparison of visual acuity and contrast sensitivity between femto laser in situ keratomileusis and orthokeratology for low-tomoderate myopia. Eye Contact Lens 2018;44:S194–S198.