Three years experience of myopia control with contact lenses in Berne

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Background

Since 2000 the global prevalence of myopia is raising [1]. Today, myopia and associated conditions are considered to belong to the six leading causes of vison loss worldwide [2]. Atropine, pirenzepine and specialty contact lenses are recommended today to delay myopia progression [3]. Contact lenses with especially designed optical effect were studied regarding effectivity and saftey [4,5]. Since 2014 specifically selected contact lens designs are in practice use in Berne in an ophthalmological-optometrical cooperation.

Material and Methods

Since May 2014, suitable children and youths with a spherical equivalent (SE) refractive error of at least -1.0 diopters (D) and myopic progression, and their parents were fully informed about specifically selected contact lenses as an alternative to spectacles. All patients received a comprehensive eye examination inlcuding cycloplegic refraction and optical biometry (Zeiss IOLMaster 500). Siloxan co-polymer ortho-keratology contact lenses (ortho-k) were applied overnight. Bifocal soft silicone-hydrogel contact lenses (bifoc-soft) with a recommended add power of +2.5 D for the peripheral optical zone were used during the day. Effectivity and safety of these contact lens types was studied retrospectively. Except for myopic refractive error, only healthy eyes were included in the analysis. A group of age and ethnicity correlated children wearing ordinary single vision spectacles (glasses) served as control group. The annual change of SE refraction and axial length was calculated for the bifoc-soft contact lens and the spectacles groups, the annual change of axial length for the ortho-k group. Wilcoxon rank-sum tests were performed and results were considered statistically significant if the p-values were <0.05.

 

Authors

Alexander Meyenberg (MD)

Michael Bärtschi (PhD)

Marc Fankhauser (BSc)

eyeness

Financial interests: Consultant: Being a consultant of a company or compending company with business interests in the topic

Grants: None

Material and Methods

Since May 2014, suitable children and youths with a spherical equivalent (SE) refractive error of at least -1.0 diopters (D) and myopic progression, and their parents were fully informed about specifically selected contact lenses as an alternative to spectacles. All patients received a comprehensive eye examination inlcuding cycloplegic refraction and optical biometry (Zeiss IOLMaster 500). Siloxan co-polymer ortho-keratology contact lenses (ortho-k) were applied overnight. Bifocal soft silicone-hydrogel contact lenses (bifoc-soft) with a recommended add power of +2.5 D for the peripheral optical zone were used during the day. Effectivity and safety of these contact lens types was studied retrospectively. Except for myopic refractive error, only healthy eyes were included in the analysis. A group of age and ethnicity correlated children wearing ordinary single vision spectacles (glasses) served as control group. The annual change of SE refraction and axial length was calculated for the bifoc-soft contact lens and the spectacles groups, the annual change of axial length for the ortho-k group. Wilcoxon rank-sum tests were performed and results were considered statistically significant if the p-values were <0.05.

Results

138 eyes of 71 patients between the age of 7 and 18 years, mean 12.9 ± SD 2.1 years, were included, 12 patients (7 females, 5 males) choosing otho-k contact lenses, 14 patients (9 females, 5 males) bifoc-soft contact lenses, 45 patients (17 females, 28 males) spectacles. Full data sets including valid optical biometry measures were availabe for 24 eyes of the ortho-k group, 27 eyes of the bifoc-soft group, 87 eyes of the glasses group, respectively. Follow-up was 139 to 883 days, mean 520.8 ± SD 203.4 days. Contact lens fitting was successful in 92% of cases, all without complications during the follow-up period.

Table 1.

 

Ortho-k

Bifoc-soft

Glasses

Eyes / patients (n)

14 / 7

13 / 7

27 / 14

Females / males (n)

4 / 3

4 / 3

5 / 9

Age mean ± SD (years)

12.3 ± 2.4

12.2 ± 1.9

12.1 ± 1.5

Moderate or high myopic parents (%)

57

86

71

Follow-up mean ± SD (days)

604.5 ± 180.0

744.5 ± 82.6

595.7 ± 154.9

SE refractive error at first visit, mean ± SD (D)

-2.841 ± 1.510

-4.212 ± 1.720

-2.949 ±1.333

Annual change of SE refraction error, mean ± SD (D)

non available

-0.333 ± 0.257

-0.301 ± 0.255

Axial length at first visit, mean ± SD (mm)

24.566 ± 0.997

25.369 ± 0.965

24.381 ± 1.014

Annual change of axial length, mean ± SD (mm)

0.059 ± 0.072

0.175 ± 0.081

0.131 ± 0.094

Table 1 presents the patient demographics and annual changes in refraction and axial length of the age and caucasian ethnicity correlated groups. Eyes of the bifoc-soft group had longer axial length und higher SE refractive error at first visit, compared to the ortho-k and glasses groups. The annual change of SE refraction error was not significantly different between the bifoc-soft group and the glasses group (p=0.729). Only ortho-k contact lens wearers showed significantly lower annual axial length elongation, compared to the glasses control group (- 55%, p=0.038).

Discussion

More parents did choose glasses than contact lenses for their children and youths during our observation period. Males represented the larger proportion in the glasses group, females represented the larger proportion in the contact lens groups. Socioeconomic factors and gender differences were beyond the scope of our study. Cheung et al. [6] examined Hong Kong parents' knowledge on myopia control strategies available. He reported that ortho-k contact lenses were the most commonly known myopia control strategy and that safety in contact lens wear was a major concerne among Hong Kong parents.

In our study, contact lens fitting was successful in 92% of cases and no contact lens complications were observed. Bullimore [5] reviewed studies representing 1800 patient years of contact lens wear in 7- to 19-year-olds. He found that the incidence of corneal infiltrative events in children is similar to or even lower than in adults.

In contrast to other studies in this area [3,4,7], we found no reduction of myopa progression with bifocal soft contact lenses in our Bernese population. We assume that a higher variability in the bifocal contact lens products and the add powers used may have contributed to these differences. In very good accordance with other studies [3,4,7], Ortho-k contact lenses showed a 55 % inhibition of axial length elongation in our Bernese children and youths. We are aware of the small study sample as a limitation of our study.

Conclusions

Ortho-k and bifocal silicone-hydrogel contact lenses showed a high level of safety for children and youths. Ortho-k contact lenses are a promising strategy to reduce myopia progression.

References

1.Holden, B.A., et al., Global Prevalence of Myopia and High Myopia and Temporal Trends from 2000 through 2050. Ophthalmology, 2016. 123(5): p. 1036-42.

2.Saw, S.M., A synopsis of the prevalence rates and enviromental risk factors for myopia. Clin Exp Optom 2003. 86: p. 289-94.

3.Huang, J., et al., Efficacy Comparison of 16 Interventions for Myopia Control in Children: A Network Meta-analysis. Ophthalmology, 2016. 123(4): p. 697-708.

4.Turnbull, P.R., et al., Contact Lens Methods for Clinical Myopia Control. Optom Vis Sci, 2016. 93(9): p. 1120-6.

5.Bullimore, M.A., The Safety of Soft Contact Lenses in Children. Optom Vis Sci, 2017.94(6): p. 638-46.

6.Cheung S.W., et al., Parents' knowledge and perspective of optical methods for myopia control in children. Optom Vis Sci, 2014. 91(6): p. 634-41.

7.Smith M.J., et al., Controlling myopia progression in children and adolescents. Adolesc Health Med Ther, 2015. 13(6): p. 133-40.

 

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