OrthoK lenses: Possible long-term axial length shortening for myopic patients

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Long-term shortening of the axial length in myopic patients who wear orthokeratology lenses is possible, according to a study led by Yin Hu, MD, and colleagues. The investigative team is from the State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou, China.¹

Myopia is a vision-threatening disease that has become a worldwide public health problem. The key characteristic of myopia is the pathologically rapid elongation of axial length (AL), the authors commented.

“It has been firmly established that accelerated AL growth manifests years before disease onset.^2,3 After myopia has developed, the more rapid than normal AL progression continues⁴ and typically stabilizes at approximately 16 years of age.⁵ In some instances, axial elongation endures into early adulthood, albeit slower than that in children,"⁶ the authors explained.

In myopic patients, excessive elongation of the axial length can lead to irreversible vision loss. A number of treatments have been investigated to prevent the ocular elongation, such as orthokeratology lenses,^7,8 atropine drops,^9,10 bi- and multifocal soft contact lenses^11,12 and spectacles with specific optical designs.^13,14

The authors of the study under discussion set out to determine the percentage, probability and time course of long-term AL shortening in patients wear myopic orthokeratology lenses based.

The authors retrospectively reviewed 142091 medical records of 29825 subjects collected over the course of 10 years in the orthokeratology database of 1 hospital.

The investigators defined long-term AL shortening as a change of -0.1 mm or less in AL at any follow-up evaluation after 1 year.

Analysis of orthokeratology wearers

Ultimately, 10093 subjects (mean initial age, 11.70 years; 58.8% female) who had undergone 80778 visits were included.

Of those patients, 16.47% (n=1,662) had long-term AL shortening (95% confidence interval, 15.75%–17.21%). The age when the subjects started wearing these lenses was the most relevant factor in the shortening of the axial length.

The investigators reported, “The initial age had a significant impact on the incident occurrence (odds ratio, 1.37; 95% confidence interval, 1.34–1.40; P < 0.001). The estimated probability of AL shortening was approximately 2% for subjects with an initial age of 6 years and 50% for those aged 18 years.”

The median magnitude of the maximal AL reduction was 0.19 mm in the 1,662 patients who experienced shortening of the axial length. The authors found that the shortening of the axial length was seen for the most part during the first 2 years of wearing of the lenses.

The authors concluded, “This study reported that 16% of patients who wear myopic orthokeratology lenses experience long-term ocular axial shortening. Age exerts a significant influence on the incident occurrence. The shortening process is dominantly accomplished within the initial 2 years of lens wear and does not vary significantly with subject characteristics.”

The investigators advised that additional should provide detailed ocular biometric changes and potential mechanisms that drive this phenomenon.

References:

1. Hu Y, Ding X, Jiang J, et al. Long-term axial length shortening in myopic orthokeratology: incident probability, time course, and influencing factors. 2023;64:37. doi:https://doi.org/10.1167/iovs.64.15.37

2. Mutti DO, Hayes JR, Mitchell GL, et al. Refractive error, axial length, and relative peripheral refractive error before and after the onset of myopia. Invest Ophthalmol Vis Sci. 2007;48:2510–2519.

3. Xiang F, He M, Morgan IG. Annual changes in refractive errors and ocular components before and after the onset of myopia in Chinese children. Ophthalmology. 2012;119:1478–1484.

4. Jones LA, Mitchell GL, Mutti DO, et al. Comparison of ocular component growth curves among refractive error groups in children. Invest Ophthalmol Vis Sci. 2005;46:2317–2327.

5. Myopia stabilization and associated factors among participants in the Correction of Myopia Evaluation Trial (COMET). Invest Ophthalmol Vis Sci. 2013;54:7871–7884.

6. Lee SS, Lingham G, Sanfilippo PG, et al. Incidence and progression of myopia in early adulthood. JAMA Ophthalmol. 2022;140:162–169.

7. Cho P, Cheung SW. Retardation of myopia in Orthokeratology (ROMIO) study: a 2-year randomized clinical trial. Invest Ophthalmol Vis Sci. 2012;53:7077–7085.

8. Swarbrick HA, Alharbi A, Watt K, Lum E, Kang P. Myopia control during orthokeratology lens wear in children using a novel study design. Ophthalmology. 2015;122:620–630.

9. Chia A, Lu QS, Tan D. Five-year clinical trial on atropine for the treatment of myopia 2: myopia control with atropine 0.01% eyedrops. Ophthalmology. 2016; 123:391–399.

10. Yam JC, Zhang XJ, Zhang Y, et al. Three-year clinical trial of Low-Concentration Atropine for Myopia Progression (LAMP) study: continued versus washout: phase 3 report. Ophthalmology. 2022;129:308–321.

11. Walline JJ, Walker MK, Mutti DO, et al. Effect of high add power, medium add power, or single-vision contact lenses on myopia progression in children: the BLINK randomized clinical trial. JAMA. 2020;324:571–580.

12. Chamberlain P, Bradley A, Arumugam B, et al. Long-term effect of dual-focus contact lenses on myopia progression in children: a 6-year multicenter clinical trial. Optom Vis Sci. 2022;99:204–212.

13. Lam CS, Tang WC, Lee PH, et al. Myopia control effect of defocus incorporated multiple segments (DIMS) spectacle lens in Chinese children: results of a 3-year follow-up study. Br J Ophthalmol. 2022;106:1110–1114.

14. Li X, Huang Y, Yin Z, et al. Myopia control efficacy of spectacle lenses with aspherical lenslets: results of a 3-year follow-up study. Am J Ophthalmol. 2023; 253:168–168.