A Mathematical Model for Axial Length Estimation in a Myopic Pediatric Population Based on Easily Obtainable Variables

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

please find enclosed

Comments for author File: Comments.pdf

Author Response

The authors would like to thank the reviewers for their kind words and help in improving this manuscript. Following the suggestions, a comment on myopia monitoring based on periodic assessment of the refractive status has been added to the manuscript. In addition, the use of a subjective refraction method with accommodation control, the fogging technique, has been emphasised. As the reviewer suggests, the main changes incorporated for the improvement of the manuscript have been made primarily in the discussion section. In addition, other minor modifications were performed to enhance the report's readability. The authors hope that this version will be more in line with the reviewers' standards.

Reviewer 2 Report

Comments and Suggestions for Authors

The quality of this manuscript is good, and it is almost ready for publication. The subject is pertinent for publication. The comments to the authors are listed below.

ABSTRACT

Lign 14: Many devices on the market are easy to use, even in the pediatric population. Axial length can be measured routinely in patients five years old and older with the technology available on the market.

INTRODUCTION

Lign 57: Pirenzepine is not a valid clinical option. The authors should remove it from the manuscript.

MATERIAL AND METHODS

For the exclusions criteria, did the authors account for any level of anisometropia, or was every level of myopia difference acceptable? In the present study, both eyes were analyzed, which can impact the modelling of the data since the same height can be applied to two eyes with different spherical equivalents and curvature values. It might have been better to only use the right eye of every patient instead of both of them.

Lign 122: Can the authors explain why they didn’t use only the flat or the steep keratometry value separately instead of using the average of the flat and the steep meridian?

The absence of a significant correlation between the axial length and the age is surprising. The authors explain it in the discussion but should add that age also impacts the height value measured at the initial visit.

In the discussion, the authors should add a caution about deciding to treat or not to treat a patient based on an equation should be used with caution. There is always a significant number of outliers in a daily clinical setting.

Author Response

The quality of this manuscript is good, and it is almost ready for publication. The subject is pertinent for publication. The comments to the authors are listed below.

- Response: The authors would like to thank the reviewers for their suggestions and kind words about the manuscript. The authors believe that the comments have identified important areas that require improvement. Following the reviewers' indications, the manuscript has been edited to improve readability and clarify unclear points, with special attention to the discussion.

 

ABSTRACT

Lign 14: Many devices on the market are easy to use, even in the pediatric population. Axial length can be measured routinely in patients five years old and older with the technology available on the market.

- Response: As the reviewer correctly asserts, there are appropriate devices on the market for use in children up to five years of age. The authors' intention was to highlight that these devices, such as optical biometers, are often expensive. Conversely, there are more affordable options, such as ultrasonic biometers, but they require contact, which may be uncomfortable for children. These clarifications have been added to the Abstract.

 

INTRODUCTION

Lign 57: Pirenzepine is not a valid clinical option. The authors should remove it from the manuscript.

- Response: The authors would like to thank the reviewer for the indication. Pirenzepine has been removed from the text due to its lack of clinical applicability in the current context.

 

MATERIAL AND METHODS

For the exclusions criteria, did the authors account for any level of anisometropia, or was every level of myopia difference acceptable?

- Response: The authors agree with the reviewer on the issue indicated. The proposed model is intended to be representative of a regular clinical sample of myopic children, allowing for the generalization of the results. Including both eyes in the analysis is essential for practical clinical applications, as it reflects real-world variability, even though this may introduce some bias due to shared variables. Excluding certain levels of anisometropia may further induce bias in the applicability or the translational utility of the results. For this reason, the recruitment criteria were mainly focused on excluding the population with pathology. In the sample finally anaylsed, the lowest anisometropia recorded was 0.00 D, and the highest was 2.00 D. This information has been added to the results section to provide clarity. In addition, the possibility of discrepancies between the two eyes of the same subject has been pointed out as a possible limitation of the study in the discussion section.

 

In the present study, both eyes were analyzed, which can impact the modelling of the data since the same height can be applied to two eyes with different spherical equivalents and curvature values. It might have been better to only use the right eye of every patient instead of both of them.

- Response: Thank you for the indication. As the model is designed to be applicable in a real clinical setting, the authors consider the inclusion of inter-eye variability to be relevant. However, the reviewer is right in suggesting that the use of a shared variable (body height) may generate some bias. Despite its clinical interest, the use of both eyes of each individual can be considered a limitation of the present study. Therefore, this has been mentioned in the Discussion.

 

Lign 122: Can the authors explain why they didn’t use only the flat or the steep keratometry value separately instead of using the average of the flat and the steep meridian?

- Response: The authors decided to use mean keratometry for two reason. First, the study desing employed was stablished in accordance with the methodology employed in previous research [1, 2, 3]. Second, mean keratometry is hypothesised to be a more representative value of the overall corneal curvature and may be a more robust predictor. The study employed the spherical equivalents as the reference of the power valieble; to accurately relate this to the biometric characteristics of the eye, it is essential to use the average of the flat and steep meridian values. Using only the flat or steep keratometry value would represent just one component of the overall power, which could introduce errors or biases in the final formula. By averaging both values, a more comprehensive representation of corneal topography is ensured, which is critical for the reliability of the model. Regardless, as highlighted by the reviewer, further research is required to investigate the relationship between corneal physiognomy and ocular length.

1. Queiros, A.; Amorim-de-Sousa, A.; Fernandes, P.; Ribeiro-Queiros, M.S.; Villa-Collar, C.; Gonzalez-Meijome, J.M. Mathematical Estimation of Axial Length Increment in the Control of Myopia Progression. J Clin Med 2022, 11.
2. Morgan, P.B.; McCullough, S.J.; Saunders, K.J. Estimation of ocular axial length from conventional optometric measures. Cont Lens Anterior Eye 2020, 43, 18-20.
3. Lingham, G.; Loughman, J.; Panah, D.S.; Harrington, S.; Saunders, K.J.; Ying, G.S.; Cui, H.; Kobia-Acquah, E.; Flitcroft, D.I. The long and short of it: a comprehensive assessment of axial length estimation in myopic eyes from ocular and demographic variables. Eye (Lond) 2024, 38, 1333-1341.

 

The absence of a significant correlation between the axial length and the age is surprising. The authors explain it in the discussion but should add that age also impacts the height value measured at the initial visit.

- Response: Thank you very much for the indication. The authors agree with the reviewer in pointing out that age and body height are good correlates, so it is even more surprising that only one of these parameters is significant for the model. A comment on this has been added to the discussion section.

 

In the discussion, the authors should add a caution about deciding to treat or not to treat a patient based on an equation should be used with caution. There is always a significant number of outliers in a daily clinical setting.

- Response: Thank you for the suggestion. In the conclusion section, the informative nature of the formula has been emphasised.