Short-Term Axial Length Changes in Myopic Eyes Induced by Defocus Spectacles for Myopia Control

Round 1

Reviewer 1 Report (New Reviewer)

In this manuscript entitled “Short-term Axial Length Changes in Myopic Eyes, Induced by Defocus Spectacles for Myopia Control”, the authors designed a special defocus spectacles having a central zone with clear distance vision and a peripheral zone with +3.50 dioptres add, and tested in a small group of young myopic subjects. The results were not surprisingly consistent with reports in the literature that short-term axial length changes came from the changes in the choroidal thickness, and the peripheral defocus affected the on-axis choroidal thickness.

In the introduction session, multiple places appear the “hyperopic defocus”, authors should double-check should it be “myopic defocus” since I believe researchers in the optical field should test a lens design to slow down myopic eye growth by peripheral myopic defocus, not hyperopic defocus, which would induce myopia development at least in animal studies.

Figure 2, among 17 subjects tested, four of them had different choroidal responses either after the first session of reading or after the second session of reading. It would be more informative if authors can discuss these different cases.

Author Response

In this manuscript entitled “Short-term Axial Length Changes in Myopic Eyes, Induced by Defocus Spectacles for Myopia Control”, the authors designed a special defocus spectacles having a central zone with clear distance vision and a peripheral zone with +3.50 dioptres add, and tested in a small group of young myopic subjects. The results were not surprisingly consistent with reports in the literature that short-term axial length changes came from the changes in the choroidal thickness, and the peripheral defocus affected the on-axis choroidal thickness.

We agree and are grateful for your comments.

In the introduction session, multiple places appear the “hyperopic defocus”, authors should double-check should it be “myopic defocus” since I believe researchers in the optical field should test a lens design to slow down myopic eye growth by peripheral myopic defocus, not hyperopic defocus, which would induce myopia development at least in animal studies.

This is right as you say, we made a mistake in that sense that has been corrected.

Figure 2, among 17 subjects tested, four of them had different choroidal responses either after the first session of reading or after the second session of reading. It would be more informative if authors can discuss these different cases.

Now the legend in Figure 2 shows that four subjects randomly shortened eyes with both experimental paradigms.

Reviewer 2 Report (New Reviewer)

This study looks at a novel lens design and its effect on axial length after reading. They found that normal spectacles lenses caused+8 microns of enlongation while the novel lens design showed significant shortening of axial length. This is interesting because the shortening of axial length occurred on a scale of minutes and not days or weeks.

This is an interesting outcome and the manuscript is probably worth publishing. There are some concerns, however. For some reason, there was verbal consent given and there was no mention of signed informed consent. In the future, I'd recommend written signed consent.

The subject age range was 18 to 25 years old. In most myopia studies we look at school-aged children because this is when myopia begins and when the anti-myopia treatments are applied. Consider completing this study with children.

I think more work needs to be done on the lens design. A 9mm center is very small diameter. It is not surprising that study subjects would have a difficult time walking with the lenses in place. It is possible, even probable, that the center diameter with distance prescription could be made larger and therefore the lenses would be more tolerable. It seems like more work should be completed on this before settling in on this lens design.

We don't use the term "super-diluted." The term "dilute atropine" will suffice.

Author Response

This study looks at a novel lens design and its effect on axial length after reading. They found that normal spectacles lenses caused+8 microns of enlongation while the novel lens design showed significant shortening of axial length. This is interesting because the shortening of axial length occurred on a scale of minutes and not days or weeks.

This is an interesting outcome and the manuscript is probably worth publishing. There are some concerns, however. For some reason, there was verbal consent given and there was no mention of signed informed consent. In the future, I'd recommend written signed consent.

As we comment on Reviewer 3, Ethics approval of a longitudinal trial has been obtained and there is a recommendation for two written informed consents, one for the child in simple language and one for the parents. We are glad that this is so and for the recommendation of the Reviewer.

The subject age range was 18 to 25 years old. In most myopia studies we look at school-aged children because this is when myopia begins and when the anti-myopia treatments are applied. Consider completing this study with children.

The newly approved study will involve children aged 8 to 14 at baseline as you suggest.

I think more work needs to be done on the lens design. A 9mm center is very small diameter. It is not surprising that study subjects would have a difficult time walking with the lenses in place. It is possible, even probable, that the center diameter with distance prescription could be made larger and therefore the lenses would be more tolerable. It seems like more work should be completed on this before settling in on this lens design.

Concerning the issue of the central 9mm zone for distance that should be bigger for easier adaptation, we must bear in mind that HOYA and ESSILOR spectacles have both shown 70% effectivity with such a 9mm distance central zone, and that the studies with orthok have shown that the smaller central distance zone is more effective. Besides, with OCT imaging we have shown that our defocussed images fall at the retinal paramacular zone that is most sensitive to blur and defocus, as we have said under review in OPO (https://ssrn.com/abstract=4325067).

We don't use the term "super-diluted." The term "dilute atropine" will suffice.

Agreed and changed accordingly.

Reviewer 3 Report (New Reviewer)

This paper is clear, well structured  and relevant to the field. Number of cititations is excessive and cited references are recent and relevant. The hypothesis of the paper although relevant is already under reasearch by other authors. Experimental design is appropriate to test the hypothesis although the number of test subjects schould be bigger . Manuscript results are reproducible based on the details given in the methods. Figures and tables are appropriate and properly show data. Conclusions are consistent with arguments. However in my opinion the number of testing subjects schoud be bigger as well as the longer time of testing. So I recommend (encourage) longer trial with bigger  testing subjects numbers.

Author Response

This paper is clear, well structured  and relevant to the field. Number of cititations is not excessive and cited references are recent and relevant. The hypothesis of the paper although relevant is already under reasearch by other authors. Experimental design is appropriate to test the hypothesis although the number of test subjects schould be bigger . Manuscript results are reproducible based on the details given in the methods. Figures and tables are appropriate and properly show data. Conclusions are consistent with arguments. However in my opinion the number of testing subjects schoud be bigger as well as the longer time of testing. So I recommend (encourage) longer trial with bigger  testing subjects numbers.

We are grateful with the reviewers comments in the sense that this study was developed and performed one year ago by now and as we had these encouraging results described by other research groups as well as by us, we tested where the images were falling in the retinal level with our defocus spectacles with OCT imaging discovering that the defocussed blurred area was falling at the highest blur sensitive retina. This paper is posted in SSRN and under review (https://ssrn.com/abstract=4325067), and after one year we finally have Ethics approval for a longitudinal trial for two years testing compliance and effectivity of this design in 50 children aged 8 to 14 years old at baseline. Enrolment has just began. So what reviewer recommends is underway.

Reviewer 4 Report (New Reviewer)

Well done

Author Response

We are grateful for reviewer's encouraging report.

Round 2

Reviewer 3 Report (New Reviewer)

I encourage you to continue your work

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Thank you for the opportunity to review. The work is interesting however I have the following comments.

What is conspicuously missing from the introduction is information on what changes in the length of the eyeball in humans entail. Adding this information will improve citation and interest in the work. Please add.

Information about the normal length of the eyeball (about 23.75 mm) - 10.1111/opo.12728

Information about the elongation of the eyeball and the exact values of this elongation in myopic people

The eyeball length is 24 mm for low myopia (−6 D < refractive error <0 D), high myopia is approximately 30 mm (refractive error < −6 D) - 10.1159/000317072

Correlation between the length of the eyeball and the muscle tensions - 10.1155/2022/6115782

Please rephrase the objective to be clearer and add a research hypothesis.

In methods and materials  - Information on sample size calculations is missing.

Figure 2. - please insert graphics of good quality, not photocopies.

Table 2. - exact ''p'' values should be given.

Please add clearly defined conclusions in a new paragraph.

Citations and bibliographies should be corrected according to the journal's standards.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Dear authors,

The work is particularly interesting,  even if it needs some improvements.

My specific comments are:

- The paper needs a professional English editing.

-In accordance with the authors' guidelines, the abstract should state background instead of purpose.

- I recommend a scan of the image rather than a photo.

-In the text, reference numbers should be placed in square brackets [ ].

- The discussion section needs to be improved with more references from the literature.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

General comments

The work of Iribarren et al. attempts to evaluate the potential efficacy of a novel spectacle lens for myopia control.

The work is based on the hypothesis that changes in choroidal thickness that precede changes in eye length and myopia are measurable not only in school children but also in young adults. In the experiments, 17 subjects aged 18-25 had to read texts with their normal single vision lenses and with a new “defocus spectacle lens”. Eye length was measured accurately after each reading session. The results showed that the axial length of the eye after reading was shorter with the new “defocus lenses” than with the normal lenses.

The authors conclude that the new defocus spectacle lenses could be tested on children for myopia control. 

The introduction clearly describes the current status of myopia research.

The section on materials and methods could be slightly improved by adding information on the design of the new lens (see comment below).

In the results section, the relevant findings are presented. Here I would have liked additional results about the visual acuity through the new lens in different off-centre directions of gaze, however, this is not mandatory. The visual field in figure 2 already says a lot.

In the discussion section, important issues are addressed - for example, the effect that the new lenses are good for reading but not so good for walking on the street.

The relevant literature is cited.

Specific comments

Line 49: I am not aware that the manufacturers of myopia control glasses claim that their glasses stop the progression of myopia. I suggest using a different word instead of “arresting myopia progression”, e.g. "reducing myopia progression".

Lines 96 and 122-126: Some well-known manufacturers have already launched myopia control lenses with a peripheral defocus. These lenses are similar in design to progressive lenses. However, they have the progressive zones only in the horizontal meridian. Therefore, I would like to know more about the design of the new lens. What is similar to the existing designs? What is different? The reference (21) is not accessible to all readers. Please add a short paragraph or illustration showing the main features. Can you say something about the peripheral astigmatism in the transition zone? What is the refractive power of the new lens in the lower part of the lens where the reading addition of a normal progressive lens would be?

References: In the section references, all journal names should be abbreviated according to the publisher's specifications.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf