PONE-D-19-31270

Willingness to Pay for Cataract Surgery and Associated Factors among Cataract Patients in Outreach Site, North West Ethiopia

PLOS ONE

Dear Mr. Amare,

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.

We would appreciate receiving your revised manuscript by Jun 27 2020 11:59PM. When you are 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.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter.

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

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). This letter should be uploaded as separate file and labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. This file should be uploaded as separate file and labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. This file should be uploaded as separate file and labeled 'Manuscript'.

Please note while forming your response, if your article is accepted, you may have the opportunity to make the peer review history publicly available. The record will include editor decision letters (with reviews) and your responses to reviewer comments. If eligible, we will contact you to opt in or out.

We look forward to receiving your revised manuscript.

Kind regards,

Janhavi Ajit Vaingankar

Academic Editor

PLOS ONE

Journal Requirements:

When submitting your revision, we need you to address these additional requirements.

1. Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. The PLOS ONE style templates can be found at https://journals.plos.org/plosone/s/file?id=wjVg/PLOSOne_formatting_sample_main_body.pdf and https://journals.plos.org/plosone/s/file?id=ba62/PLOSOne_formatting_sample_title_authors_affiliations.pdf

2. Please address the following:

- Please include additional information regarding the survey or questionnaire used in the study and ensure that you have provided sufficient details that others could replicate the analyses. For instance, if you developed a questionnaire as part of this study and it is not under a copyright more restrictive than CC-BY, please include a copy, in both the original language and English, as Supporting Information.

- Please ensure you have thoroughly discussed any potential limitations of this study within the Discussion section.

- Please refrain from reporting p values as 0.000, either report the exact value or use the format p<0.0001.

Thank you for your attention to these queries.

3.  We suggest you thoroughly copyedit your manuscript for language usage, spelling, and grammar. If you do not know anyone who can help you do this, you may wish to consider employing a professional scientific editing service.  

Whilst you may use any professional scientific editing service of your choice, PLOS has partnered with both American Journal Experts (AJE) and Editage to provide discounted services to PLOS authors. Both organizations have experience helping authors meet PLOS guidelines and can provide language editing, translation, manuscript formatting, and figure formatting to ensure your manuscript meets our submission guidelines. To take advantage of our partnership with AJE, visit the AJE website (http://learn.aje.com/plos/) for a 15% discount off AJE services. To take advantage of our partnership with Editage, visit the Editage website (www.editage.com) and enter referral code PLOSEDIT for a 15% discount off Editage services.  If the PLOS editorial team finds any language issues in text that either AJE or Editage has edited, the service provider will re-edit the text for free.

Upon resubmission, please provide the following:

• The name of the colleague or the details of the professional service that edited your manuscript
• A copy of your manuscript showing your changes by either highlighting them or using track changes (uploaded as a *supporting information* file)
• A clean copy of the edited manuscript (uploaded as the new *manuscript* file)

4. We note that you have indicated that data from this study are available upon request. PLOS only allows data to be available upon request if there are legal or ethical restrictions on sharing data publicly. For information on unacceptable data access restrictions, please see http://journals.plos.org/plosone/s/data-availability#loc-unacceptable-data-access-restrictions.

In your revised cover letter, please address the following prompts:

a) If there are ethical or legal restrictions on sharing a de-identified data set, please explain them in detail (e.g., data contain potentially identifying or sensitive patient information) and who has imposed them (e.g., an ethics committee). Please also provide contact information for a data access committee, ethics committee, or other institutional body to which data requests may be sent.

b) If there are no restrictions, please upload the minimal anonymized data set necessary to replicate your study findings as either Supporting Information files or to a stable, public repository and provide us with the relevant URLs, DOIs, or accession numbers. Please see http://www.bmj.com/content/340/bmj.c181.long for guidelines on how to de-identify and prepare clinical data for publication. For a list of acceptable repositories, please see http://journals.plos.org/plosone/s/data-availability#loc-recommended-repositories.

We will update your Data Availability statement on your behalf to reflect the information you provide.

Additional Editor Comments (if provided):

[Note: HTML markup is below. Please do not edit.]

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: Yes

Reviewer #2: Partly

Reviewer #3: Partly

**********

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

Reviewer #1: N/A

Reviewer #2: I Don't Know

Reviewer #3: I Don't Know

**********

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: Yes

Reviewer #3: No

**********

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: No

Reviewer #2: No

Reviewer #3: No

**********

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: Access to healthcare is a fundamental human right. Understanding the willingness to pay for cataract surgery and the associated factors are crucial in designing self-sustaining and efficient eyecare programs. I applaud the authors for contributing to the body of evidence.

However, as there was no line number given in the manuscript, sticky-notes were used (by the reviewer) to provide specific comments on the manuscript. It is highly recommended to use line numbers in the next versions. The sticky notes contain comments targeted to specific sentences or wordings; whereas the suggestions shared here are more general in nature. Authors are suggested to first go through the general-comments and then check the sticky-note-comments.

Suggestions for improvement are as follows:

1. The manuscript (including the abstract) demands massive improvement in writing. Moreover, there are typos and grammatical errors that need to be corrected.

2. WTP are health-state dependent, hence, it depends on the context and techniques applied (e.g. double bounded dichotomous choices) to elicit WTP. Sharing the tool (as supplementary documents) might be a good to option to let the reader understand the WTP estimation techniques applied in this study.

3. Generally outreach-sites are socio-demographically different from the general population. A comparison of socio-demographic characteristics between the sample and general population of North-West-Ethiopia or Ethiopia might provide a better understanding of the sample as-well-as understanding the differences in WTP in general context.

4. The ‘Introduction’ mentions about the mean costs of cataract surgery in Europe and USA. The cost of the surgery varies across the globe. As the study estimates the WTP for cataract surgery in Ethiopia, it would be wise to also state literatures that estimate WTP of other African and Asian countries (similar economies).

5. The ‘Introduction’ ends with a non-justifiable argument (Please check the sticky-note-comment). The manuscript states about the context-dependent WTP, however, it does not state any literature on context or health-state dependencies of estimated WTP. Also, please provide a detailed description of the context (i.e. WTP elicitation approach) in the method section.

6. There are various surgical techniques of cataract surgery (e.g. Small incision cataract surgery, phacoemulsification). For which technique of surgery respondents elicited their WTP for? Did they have full information or any prior knowledge on the surgical procedure(s)?

7. The ‘Study design and setting’ section should focus on the eyecare provided by the hospital. Please provide a summary of the eyecare facilities available in North West Ethiopia. It will help the reader to understand the representativeness of the setting (i.e. hospital) from which respondents were selected.

8. The ‘Study population and sampling technique’ section needs to improve its clarity in describing the sampling technique used for the study. Simple random sampling technique requires selecting subjects from a predetermined sampling frame. If the list of 1336 cataract patients was used as the sampling frame, then at least two things needs to be clarified:

(a) The sampling frame was prepared based on the patients visited the facility from June 10, 2018 to June 17, 2018; were the subjects chosen on a daily basis or based on an aggregated list.

(b) As the program provides free of cost cataract surgery, the subjects interviewed in this study should already have a preconceived estimation about the cost of the treatment; this has a definite impact on the elicited WTP (e.g. only 55 percent respondents elicited a non-zero WTP).

9. The description of bidding procedure given in page 5 needs clarity. How was initial bid (i.e. 1000 ETB) was chosen? A schematic representation of the DBDC experiment would help reader to visualize the context better. Please check the following reference:

[Islam M.N., Engles T., Hossain S., Sarker M., Rabbani A. “Willingness-to-pay for cataract surgeries among patients visiting eye-care facilities in Dhaka.” Applied Health Economics and Health Policy 17, no. 4 (2019): 545-554. DOI: 10.1007/s40258-019-00478-3]

10. About 45 percent respondents were not willing to pay a positive price for the service, how were these responses handled in the analysis? In addition, if some people were not willing to pay, were these people statistically different from those that were willing to pay?

11. The DBDC experiment ends with an interval of WTP. Did you check the interval regression techniques to estimate the associated factors? (If yes) Were the results different with an interval regression model?

12. The average WTP can be estimated using a constant only interval regression model. Although, 45 percent respondents did not elicit a positive WTP, their true WTP might be greater than zero but less than the last bid (750 ETB). In that case counting them as zero (as done in this manuscript) might not be pragmatic. Please check the following reference:

[Islam, M.N., Rabbani, A. & Sarker, M. “Health shock and preference instability: assessing health-state dependency of willingness-to-pay for corrective eyeglasses.” Health Economics Review 9, no. 1 (2019): 32. DOI:10.1186/s13561-019-0249-3]

13. The robustness of the Tobit models can be checked estimating coefficients of both censored and truncated samples as-well-as estimating the OLS coefficients. Please report the results (as supplementary documents). This practice will help the readers understand the robustness of the results obtained by the study.

14. The ‘Participant’s health-related characteristics’ section requires to provide sufficient details of the variables (what and how the measurements were taken; e.g. Systemic illness).

15. The discussion and conclusion need to be improved.

Reviewer #2: Dear Editor,

Thank you for inviting me to review this interesting article on willingness to pay for cataract surgery. The authors have attempted to tackle a very pertinent issue in appropriate pricing of cataract surgery. However, there are some concerns.

The overall standard of academic English is low and one has to struggle to read between the lines to understand the otherwise important information being conveyed. May I suggest the authors seek professional assistance is preparing the grammatical content of the manuscript.

Many of the references are out of date. There are more recent references on the prevalence and causes of blindness, globally.

In the Methods section, the authors state that all patients admitted for cataract surgery at Tebbe Gion Hospital formed the study population, then mentions that the patients were screened for cataract. What was the purpose of the screening?

When was this study conducted?

Several unfamiliar analytical terms are mentioned.

Double Bounded Dichotomous Choice Variant of the Contingent Valuation (CV)

Principal Component Analysis (PCA)

Homoscedasticity of error terms through Breush-pagan for Heterosekedasticity test

The authors should briefly explain what they are and put a reference as this is a broad remit medical journal.

The authors mention visual ability score; an unusual term to assess visual acuity. Standard visual acuity measures are available e.g. Snellens notation or the logMAR.

In summary, I believe the authors have an important message to convey, but this is obfuscated in poor grammar and complex analytical terminology.

Reviewer #3: I found it quite difficult to understand the text because the English is not written in standard syntax and grammar. I strongly suggest that the authors engage the service of a professional English editing service prior to re-review of the manuscript. In addition, the methods and statistics require some more explanation for clarity and ease of understanding by the reader.

**********

6. 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: Yes: Muhammed Nazmul Islam

Reviewer #2: Yes: Dr Ada E Aghaji

Reviewer #3: 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 to be viewed.]

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 us at figures@plos.org. Please note that Supporting Information files do not need this step.

Attachments

Attachment

Submitted filename: Comments_PONE-D-19-31270_reviewer.docx

Attachment

Submitted filename: PONE-D-19-31270_reviewer.pdf

PONE-D-19-31270R1

Willingness to Pay for Cataract Surgery and Associated Factors among Cataract Patients in Outreach Site, North West Ethiopia

PLOS ONE

Dear Dr. Amare,

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.

In revising your manuscript, please consider all the comments from the reviewers carefully and elaborate on how these were addressed individually in your response to reviewers. In general, reviewers see value in your work. However, they have highlighted a number of residual and additional concerns on your manuscript. There are also several errors in the quality of grammar and writing. I urge you to consult a native English speaker or professional services to improve on the content. Your manuscript can be considered for further review only if you are willing to address these in your next revision.

Please submit your revised manuscript by Oct 05 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,

Janhavi Ajit Vaingankar

Academic Editor

PLOS ONE

[Note: HTML markup is below. Please do not edit.]

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: (No Response)

Reviewer #2: (No Response)

Reviewer #3: (No Response)

**********

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: Partly

Reviewer #3: Partly

**********

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

Reviewer #1: Yes

Reviewer #2: I Don't Know

Reviewer #3: I Don't Know

**********

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: No

Reviewer #2: Yes

Reviewer #3: 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: No

Reviewer #2: No

Reviewer #3: No

**********

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: [PONE-D-19-31270R1]

Title: Willingness to pay for cataract surgery and associated factors among cataract patients in outreach site, North West Ethiopia

I thank the editor for the opportunity to review the manuscript once again. I also appreciate the authors’ for the efforts given to revise the manuscript according to the suggestions shared. However, there are a few important issues that require additional revisions or clarifications. The suggestions are as follows:

In reply to the authors’ response to the Reviewer #1-Comment #1:

The schematic description can provide a summarized picture of the bidding, however, it will not help the reader to replicate the experiment precisely in a similar manner. Including the tool as a supplementary document will provide the chance to the reader to understand what information was given to the respondents before and while eliciting WTP. Also, it would help the reader to design a similar questionnaire/tool for their experiments.

In reply to the authors’ response to the Reviewer #1-Comment #5:

In the previous review, the author was suggested to shed some light on the health-state dependency of the WTP and discuss how that would affect the results of their study. Looking at the available literature in this context would have been an appreciable initiative. However, the current version of the manuscript neither properly discussed nor provided any reference on their statements made in this context. There are researches that provide theoretical background as-well-as empirical evidences that WTP is health-state dependent. I would request the author to re-address comment #5.

In reply to the authors’ response to the Reviewer #1-Comment #9:

The schematic description of the DBDC experiment (shown on page 9) does not contain the percentage of respondents on each of the decision nodes and the interval they ended up before answering the maximum WTP and the average maximum WTP for different paths taken. It would provide the reader with a summary of the bidding experiment and would help understand whether the prices used for the experiment were reasonable or there were too many censored observations at any particular price points. I would strongly recommend the authors consider adding the information on the diagram shown on page 9.

Moreover, the statement made in lines 147-148 of page 8 needs a proper reference. Can you please add any literature that provides a background of this 35 percent out of pocket health expenditure as a proportion of the total healthcare spending of Ethiopia?

In reply to the authors’ response to the Reviewer #1-Comment #12:

The authors mentioned that 45 percent of the respondents who did not elicit any positive WTP were excluded from the further bidding experiments. There are three issues that need to be addressed:

1. The current schematic description (shown on page 9) does not include the initial question regarding the positive WTP. Please revise it accordingly.

2. If 45 percent of the respondents are not willing to pay any positive price, then, are there any systematic differences in their sociodemographic and/or health-related characteristics? Please provide both pooled and separated descriptive statistics in Table 1 and 2. Also, test the statistical significance of the differences by conducting either bivariate analyses or test a multivariable selection model for the two groups (i.e. =1 if positive WTP, 0 otherwise).

3. As these 45 percent of the respondents did not participate in the second phase of the bidding game, the Tobit model should also be estimated for both pooled and samples with only positive WTP. The authors have already estimated the models while addressing Comment #13. However, authors may consider showing and discussing them with the main results instead of just keeping in the appendix.

General suggestions:

The regression table shared as the supplementary document does not contain all the necessary information required to assess the robustness of the results. Please provide at least the standard errors and indications of statistical significance for all the models estimated.

There are a few minor grammatical errors and typos that require correction (e.g. see lines 21-23 on page 2). There are a few technical errors too that demand authors’ attention (e.g. lines 28-29 on page 2; simple random sampling).

If possible, please use an equation writing tool (such as equation writer in MS Word) and convert the lines 230-231 into an equation.

The data needs additional clarifications and missing the original variables. Standard practice should be to share the cleaned data according to the questionnaire/tools shared. Moreover, the MWTP data contains decimal characters; are these original MWTP or convert figures?

Reviewer #2: This is a very important topic and the authors should be congratulated on carrying out this research. However, there are several concerns that have not been addressed.

Technical Issues

1. Many of the references are out of date. There is more recent data on the prevalence and causes of global blindness and visual impairment. Flaxman et al 2017, Bourne et al 2017

2. Several statements in the introduction are non- factual.

E.g. Cataract accounts for a third of all global blindness, not 51% as you stated.

Universal Eye Health from the World Health Organization's (WHO) Global Action Plan for eye health was launched in 2013, yet you provide references from 2001 and 2011.

3.. Visual acuity as classified by the WHO International classification of disease is the most common descriptor for assessing vision. You insist on using visual ability. The references you quote for visual ability are silent on this terminology.16, 18, 20-22, 24-27

Grammatical issues.

4. Incorrect grammar and syntax through out the article.

Reviewer #3: I appreciate the fact that the authors have made concerted efforts to improve the quality of the manuscript. However, I still had considerable difficulty with understanding the text and deciphering the message that the authors want to communicate to the reader. I do understand that English is not the first language of the authors but in order to ensure effective communication, the manuscript must be intelligible. Therefore, I wish to repeat my suggestion that the authors engage the service of a professional English editing service before re-review of the manuscript.

**********

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: Yes: Ada Aghaji

Reviewer #3: 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.

Attachments

Attachment

Submitted filename: Comments2_PONE-D-19-31270R1_Reviewer1.docx

PONE-D-19-31270R2

Willingness to Pay for Cataract Surgery and Associated Factors among Cataract Patients in Outreach Site, North West Ethiopia

PLOS ONE

Dear Dr. Amare,

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 26 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,

Janhavi Ajit Vaingankar

Academic Editor

PLOS ONE

[Note: HTML markup is below. Please do not edit.]

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: (No Response)

Reviewer #2: (No Response)

**********

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: Partly

Reviewer #2: No

**********

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

Reviewer #1: Yes

Reviewer #2: I Don't Know

**********

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: No

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: No

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: I thank the editor for the opportunity to review the manuscript for the third time. I also appreciate the authors’ for the efforts given to revise the manuscript according to the suggestions shared. However, there are a few inconsistencies that need to be corrected. My comments are as follows:

1. Please mention the dates of data collection also in the main body.

2. The exchange rate used for the survey is the one of 2018. However, the world bank data the manuscript refers to in line no. 149 on page 8 is of the year 2009 (see reference no. 43). Moreover, the manuscript mentions that the out of pocket health expenditure is 35 percent of the total health expenditure in Ethiopia. Whereas, the report it refers to in reference no. 43 shows that it is 37 percent for Ethiopia. Authors should be very transparent and careful about the methodologies used and the methodologies described in the manuscript.

3. Line no. 152-154 mentions that the respondents were asked – “Are you willing to pay some positive price for cataract surgery?”, however, the questionnaire attached as a supplementary file states that, “by considering the above scenario, if the service is vailing for you, are you willing to pay something for this service”. Although, the sentences provide the same understanding of the question, there should not be any inconsistencies between what is written in the manuscript and what was actually asked. If the author wants to describe this as part of the methodology they applied; then, the exact question need not to be mentioned. This could be written differently, such as, “After briefing the case scenario, all the participants were asked whether they are willing to pay any positive price for the proposed cataract surgery”.

4. The intervals are not correctly specified in the schematic diagram. If anyone is not willing to pay 500 ETB, then the interval they fall into is 0 to <500 ETB. They intervals should be fixed by the experiment-design, not the average maximum WTP.

5. The dataset still does not contain the bidding experiment data. Sharing partial dataset will not help serving the right purpose of data-sharing.

Reviewer #2: The authors have addressed some of my comments. The main concern I had and still have is about the visual ability measurement. This is not a regular term and the authors have not defined it or explained how it was assessed. The crux of the paper is the relationship between visual ability and WTP, so this is a major flaw which the authors have not addressed. Visual acuity is usually used for WTP research. The references provided about visual ability refer to visual acuity.

**********

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.

Attachments

Attachment

Submitted filename: Comments3_PONE-D-19-31270R2_Reviewer1.docx

PONE-D-19-31270R3

Willingness to Pay for Cataract Surgery and Associated Factors among Cataract Patients in Outreach Site, North West Ethiopia

PLOS ONE

Dear Dr. Amare,

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 Feb 20 2021 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,

Janhavi Ajit Vaingankar

Academic Editor

PLOS ONE

[Note: HTML markup is below. Please do not edit.]

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)

**********

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: Partly

**********

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

Reviewer #1: Yes

Reviewer #2: I Don't Know

**********

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: No

**********

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: Thank you for considering the suggestions and making all the efforts in revising accordingly. I also thank the editor for sharing such an interesting work. Best wishes.

Reviewer #2: Some of my previous comments have been addressed. However, there are still a few concerns.

1. The quality of the grammar and syntax is not of academic standard and may require the services of a professional to bring it up to the required standard.

2. The authors have explained their methods for calculating visual ability. However, they should include references for the calculation and examples of where this has been used in ophthalmic literature. Visual ability is not a term commonly used in ophthalmic literature and the thesis of this manuscript is the relationship between visual ability and willingness to pay.

3. There are a few statements that are not factually correct. The opening sentence states that cataract is the second commonest cause of blindness worldwide; Cataract is the commonest cause of blindness globally. Refractive error is the commonest cause of visual impairment globally.

4. Cataract surgical coverage and Cataract Surgical rate are two different indicators for assessing the quantity of cataract surgery.

5. In sum therefore, I believe that this article has some merit, but a lot of work still needs to be done.

**********

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: Yes: Ada Aghaji

[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.

Willingness to Pay for Cataract Surgery and Associated Factors among Cataract Patients in Outreach Site, North West Ethiopia

PONE-D-19-31270R4

Dear Dr. Amare,

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.

An invoice for payment will follow shortly after the formal acceptance. To ensure an efficient process, please log into Editorial Manager at http://www.editorialmanager.com/pone/, click the 'Update My Information' link at the top of the page, and double check that your user information is up-to-date. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org.

If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

Kind regards,

Janhavi Ajit Vaingankar

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

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

**********

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

**********

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

Reviewer #1: 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

**********

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

**********

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: Thank you for considering the suggestions and making all the efforts in revising accordingly. I also thank the editor for sharing such an interesting work. Best wishes.

**********

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