PONE-D-20-16428

Smartphone Use while Walking Induced Optical and Vergence Aftereffects

PLOS ONE

Dear Dr. Leung,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

Although the work presented is relevant and timely, I agree with both reviewers who consider major revisions to be required prior to publication. Please revise the manuscript with particular attention to the rationale, ensuring this draws on current and appropriate literature in the field. Clarification is also needed to the methodology section, and the interpretation of statistical findings, and thus discussion.

Please submit your revised manuscript by Aug 01 2020 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

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We look forward to receiving your revised manuscript.

Kind regards,

Blanka Golebiowski, PhD BOptom

Academic Editor

PLOS ONE

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Partly

Reviewer #2: Partly

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: I Don't Know

Reviewer #2: I Don't Know

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3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: No

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4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Thank you for asking me to review this concise and easy to read manuscript. I enjoyed reading it.

Title – I don’t think that this reflects the content of the manuscript. The vergence aftereffects were not statistically significant. You haven’t mentioned that your manuscript looks at the difference between walking and sitting while using the phone.

Abstract (conclusion): Final sentence “To ensure pedestrian safety….while walking”. This does not reflect the content of your manuscript, so I think it should be removed.

Introduction, page 3, lines 70-71. “Indeed, research has revealed…..related to visual quality”. These references refer to people with visual impairment, and is a different issue altogether from the content of the rest of the paragraph (and indeed, the manuscript). If you include these references then I think you should explain what visual quality parameters cause the problem and explain how it relates to the content of the manuscript. Otherwise, I think the sentence (and references) should be removed.

Experimental protocols (page 7), 2nd paragraph. “At each visit, the experiment began with…” The word “with” needs to be included.

Experimental protocols (page 7), 2nd paragraph. Three minutes dark adaptation – it’s not clear why did you did this. Was the experiment conducted in the dark? If someone is reading from a display with the luminance at maximum level, then they would not be dark-adapted anyway. Is 3-minutes long enough to dark adapt someone – probably not? Maybe you need to say that participants were seated in a darkened room for 3 minutes – and then explain why.

Results, page 10. “J0” and “J45”. I can guess what you mean by this, but I think it would be better to explain it to the reader rather than assume that they understand.

Discussion, page 14, last sentence of paragraph 1. “The patterns of near heterophoria change were also significantly different….” On the previous page you said that they were not statistically significant but “tended to show more exo-deviation”. I think you should reword this sentence in the discussion because you cannot say that the heterophoria change was significantly different.

Discussion, page 14, paragraph 2, 1st line. “…no matter smartphone usage…”. The sentence doesn’t make sense. Have some words been omitted?

Discussion, page 14, 15, 16. You discuss the change in downward gaze angle can alter the corneal curvature and cause astigmatism, and on page 16 (2nd paragraph) you mention “working distances, gaze direction, walking gait and dynamic visual environment” as possible stressors for the eyes. However, there is no mention of neck and head angle. I know that you didn’t measure this in this study, but it might have affected your results. For example, some people hold their phone below eye level and look downwards (and this could set up the lid-effects and astigmatism). Other people don’t move their eyes downward (i.e. the eyes are in a straight-ahead gaze position) but they bend/extend their head and neck forward to view the phone in their hands. This will have a different effect on the eye/lid dynamics. I think that you should mention this issue in the discussion.

Discussion, page 14, paragraph 2. You have cited other studies that have shown induced astigmatic changes with reading and microscopy. How does the magnitude of the changes you observed compare with the magnitude of changes reported in the other studies?

Reviewer #2: Thank you for the opportunity to review this paper. Although the writing is in standard English, the logic throughout the manuscript is unclear. With the following suggestions, the manuscript may be transformed into a useful addition to the literature.

Abstract:

Authors should consider the repeatability of heterophoria measurements. There are many papers and vergence after effect measurements in determining if the statistically significant finding for the vergence after effect has any real-life or clinical significance.

Introduction:

Argument in paragraph 2 of the introduction that mobility-related accidents are closely to related to visual quality is not well argued. Authors should consider the effects of divided attention and the smartphone will occupy the central visual field so the user is relying on more peripheral vision to navigate the environment. The authors could look to data on simulated and real central and visual impairment to understand the varied effects of location of visual field defects or scotomas have on mobility performance. There is a large literature on this. Visual stress is likely to be the least important factor when it comes to mobility problems and most patients who experience visual stress will avoid the activity unless it is absolutely necessary (e.g. work and study) rather than video streaming, playing games etc. Although the authors have raised issues with smartphone use, the argument is not logical. Visual stress also has more than one meaning in the vision science literature so this term should be defined within the manuscript.

The term “optical and vergence aftereffects” is not commonly used. It might be that the authors are thinking of short-term adaptation of the fusional vergence systems. The authors should review and include some of that literature in here and revise the language used. The authors should also clearly state the hypothesis, expected findings, in lieu of current understanding of fusional vergence adaptation and how it may be affected by posture and whether they are walking or static.

Methods and Rationale for the study design:

The authors need to provide an explanation of the refractive elements of the eye and their relative contribution to final refractive outcome and explain why the focus is only on the corneal refractive component, and then in the discussion explain what this means for interpretation of the study.

The authors need to explain much more clearly, using equations, the relationship between the magnitude of corneal astigmatism as measured using Zernike polynomials and in Dioptres. It is unclear what the clinical significance of the findings are. It is unclear whether Figures 1D and E are the same data depicted in two different units, or if post-condition refraction was conducted. What would the significance of a corneal shift in astigmatism be without an understanding of how the rest of the ocular elements are changed. For example, the act of convergence may potentially change the relative location of the refractive elements within the eye.

Results:

I found the results difficult to follow and could not determine whether Bonferroni correction was applied correctly. The authors should present all results clearly in a table with the multiple comparisons clearly shown. Non-significant findings after Bonferroni correction should be considered non-significant.

Discussion:

This should be revised after considering the additional literature that the authors will have included in the Introduction.

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Reviewer #1: No

Reviewer #2: No

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

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PONE-D-20-16428R1

Changes in corneal astigmatism and near heterophoria after smartphone use while walking and sitting

PLOS ONE

Dear Dr. Leung,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

Please submit your revised manuscript by Dec 07 2020 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

• A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: http://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols

We look forward to receiving your revised manuscript.

Kind regards,

Blanka Golebiowski, PhD BOptom

Academic Editor

PLOS ONE

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

Reviewer #2: (No Response)

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2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: I Don't Know

Reviewer #2: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Well done. You've done a great job revising this manuscript. I especially like the inclusion of Table 2.

Reviewer #2: Thank you for the revision. Only one additional query has come up. When watching the movie on the smart phone, were they watching a movie in a language that required them to read the subtitles? In other words, were the subtitles an essential part of the experimental condition?

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7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Reviewer #2: No

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

Changes in corneal astigmatism and near heterophoria after smartphone use while walking and sitting

PONE-D-20-16428R2

Dear Dr. Leung,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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Kind regards,

Blanka Golebiowski, PhD BOptom

Academic Editor

PLOS ONE

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