Adaptive Optics Methods to Rat Eye Properties: Impact of Pupil Diameter on Wavefront Detection

Round 1

Reviewer 1 Report

The manuscript offers a complete investigation into the impact of pupil diameter on wavefront sensing accuracy in the rat eye—an area of significant importance for advancing adaptive optics ophthalmoscopy. The approach of combining the rat eye model simulations with experimental validations is commendable and provides a solid foundation for the conclusions drawn. However, there are some issues as follow.

1. The section 1 provides a strong rationale for the study and effectively situates it within relevant literature. However, it would benefit from a more thorough discussion of previous approaches to rat eye wavefront sensing and the limitations these have encountered.

2. The parameters of the rat eye model are briefly mentioned; however, a more detailed explanation of the selection of these specific parameters and their relevance to the study's objectives would greatly enhance reproducibility and reader understanding, such as the refractive index distribution and the rationale behind the chosen values.

3.The quality of some of the figures (e.g., FM3 is mislabeled in Fig. 2) could be improved to enhance readability.

4.There are some spelling errors in the paper, such as Fig.5(a)

5. The findings on the optimal half-filled pupil diameter for wavefront sensing in the rat eye are intriguing and merit a more detailed discussion, particularly in relation to the trade-offs involved.

6. The inverse relationship between pupil diameter and depth of focus is mentioned, but the discussion lacks a detailed exploration of how this affects wavefront sensing beyond the mention of backscattered light and artificial sensing spots. The implications of this relationship for practical wavefront sensing applications in rats could be further elaborated..

The quality of english language is fine ,but there are some mistype errors in the manuscripte should be correct.

Author Response

Thank you very much for taking the time to review this manuscript. Please find the detailed responses in the attachment. The corresponding revisions/corrections highlighted/in track changes in the response and re-submitted files.

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Reviewer 2 Report

Ophthalmoscopy equipped with adaptive optics is a viable approach for high resolution retinal imaging, which critically depends on accurate wavefront sensing. Kong et al conducted simulation and optical measurements to study the effect of pupil size on wavefront sensing in rats. The simulation modeled the rat eye as a GRIN lens and concluded that the system reached diffraction limit when the pupil is 0.8mm in diameter. However, in experimental measurement, limited improvement was observed for pupil diameter below 1.8 mm (half of the diameter of a dilated pupil). The authors concluded that half-filled pupil would provide better imaging quality.

Here are some comments for consideration:

1.      The main question I have is why the measured results are different from simulation. I don’t think this is adequately addressed in the manuscript. Is the rat eye model inaccurate or is there potentially systematics in the experimental setup. The data shown in the manuscript is insufficient to even speculate on this question. In the discussion section, the authors mentioned several possible reasons such as multi-layer scattering, etc, line 280-285, without giving any detailed explanation or quantification how these effects would produce the results seen in the experiments. It probably requires much more work to satisfactorily answer this question and I do not expect the authors to do so in revision. However, I’d like the authors to point out the potential shortcomings, if any, in their simulation or experiment in the abstract.

2.      There is no supplementary material or Data availability statement. I strongly encourage making published data available. If not, it’s impossible to reproduce any claim made in the manuscript and in return, the authors will be responsible to provide more evidence for their claims. For instance, the authors stated that, on line 145, they had minimized systematic aberration with a non-planar design. I’d suggestion adding details of this design to supplementary materials.

3.      There were 4 rats in the experiments. Please state clearly if and how the results are average over these rats. How different are their diopters measured with the tunable lens? Does results from all individual rat support the same conclusion?

4.      The statement on line 238-239 is not entirely clear to me. A summary plot would be helpful to support this statement.

5.      This is a suggestion: there is nothing wrong with starting with a table, though I found it much more inviting to have a schematic illustrating the system in question. In this case, a simple drawing illustrating the structure of the eye would be very helpful. Table 1 can be better formatted and made more compact.

Author Response

Thank you very much for taking the time to review this manuscript. Please find the detailed responses in the attachment, the corresponding revisions/corrections highlighted/in track changes in the response and re-submitted files.

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Reviewer 3 Report

In the manuscript entitled "Impact of Pupil Diameter on Wavefront Detection in Rat Eye", W. King et al. have investigated the impact of pupil diameter on wavefront estimation in the rat eye in order to achieve a high-quality wavefront sensing light spot  and accurate rat ocular aberration estimation.

First of all, reduce the length of the abstract: indicate briefly the motivation of the reported study, and the best obtained results.

Please, remove the red type in the all manuscript text.

Please, improve the manuscript layout.

Please, indicate how the parameters reported in Table 1 have been obtained.

Please, improve the quality of the schemes in Figure 2, indicating the lengths, the corners in the schemes, and in the table the units.

Please, indicate how the images and the data in the plots of Figures 3 have been obtained, reporting also the used instruments.

I can accept this manuscript with minor revision.

Author Response

Thank you very much for taking the time to review this manuscript. Please find the detailed responses in the attachment, the corresponding revisions/corrections highlighted/in track changes in the response and re-submitted files.

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Reviewer 4 Report

The article by Wen Kong etal is devoted to study of rat eye properties by methods of adaptive optics. In particular, the authors pursue an aim to solve the problem of achieving a high-quality wavefront sensing light spot and accurate wavefront estimation of the rat eye. The authors have presented the experimental results of estimating the rat’s ocular wavefront aberrations with Shark-Hartman Wave-front Sensor. In particular, it is shown that the quality of the sensing light spot improves significantly when the pupil diameter decreases from 3.6 mm to 1.8 mm. According to the authors dara, “the full width at half maximum of the sensing light spots decreases from 77.36 ± 8.95 μm to 26.78 ± 3.25 μm, and the calculated Strehl ratio increases from 0.007 to 0.396”. The main conclusion is that using a half-filled pupil for rat wavefront detection may be a more favorable choice. It provides obtaining high-resolution retinal images in the rat eye with using adaptive optics methods. 

Conclusion: The paper is very interesting and adds to results that are already published. The scientific and methodical merits of the paper are quite high. The paper can be recommended for publication in “Photonics” (MDPI) provided the authors have complied with the points listed below:

a) All presentation is made by the authors quite correctly, and do not cause any serious remarks. There are only several editorial corrections to be clarified in order to meet the possible questions of the readers:i

i). the authors should slightly clarify the title of the article in order to meet the Photonics journal imidge , for example, "Adaptive optics methods to rat eye properties study: Impact of Pupil Diameter on Wavefront Detection” (of course, at the discretion of the authors); Please explain the abbreviations in the subsection title (eg 4.3);

ii) It is well-known that the role of the wavefront sensor in the adaptive optics system is to measure deviations of the shape of the wavefront under study from the reference shape. There are three basic sensor configurations: Shack-Hartmann, shear interferometers, and curvature sensors. Each has its own advantages in noise level, accuracy, sensitivity and ease of operation with software and deformable mirrors. Although it is generally accepted that among all those listed above, the most common type is the Shack-Hartmann sensor. The latter has been used by authors. Obviously, it would be desirable to note this fact in the introduction; 

iii). When presenting and explaining the results of numerical stimulation, it would be interesting for the reader to understand the dependence of the Strehl coefficient on the number of iterations for the modified mean square method; Did the authors use an additional alternative for testing, say, a stochastic parallel gradient algorithm, etc. 

iv). Please, check that all symbols in formulas as well as abbreviatures are defined and explained; Some abbreviatures are defined a few times; e.g., modulation transfer functions (MTF), page 5, line 183; page 7, lines:255-259…

b) In order to meet the possible questions of the readers it would be appropriate to add some additional References on the known textbooks, monographies and review papers, e.g. (of course, at the discretion of the authors):

- Vorontsov M.A. and Smalgauzen V.I. Principles of adaptive optics (Nauka, Moscow, 1985);

-Glushkov A.V. and Khetselius O. Y., Biomedical Optics and Engineering (OSENU, Odessa, 2013);

- Bille J.F. (ed.) High resolution imaging in microscopy and ophthalmology: new frontiers in

biomedical optics (Cham, Springer, 2019) ;

- Lixin Liu, Zhaoqing Wu, Meijie Qi,Yanru Li, Meiling Zhang, Dingying Liao and Peng Gao, Application of Adaptive Optics in Ophthalmology. Photonics. 9(5), 288 (2022)

https://doi.org/10.3390/photonics9050288  

- Bird M. F., Kisilak M. L. and Campbell M. C. W.,

Optical Quality of the Rat Eye.Investigative Ophthalmology & Visual Science. 48(13), 2759 (2007); 

- Akyol, E., Hagag, A.M., Sivaprasad, S. et al. Adaptive optics: principles and applications in ophthalmology. Eye 35, 244–264 (2021). https://doi.org/10.1038/s41433-020-01286-z

Thanks in advance to the authors for all revisions

Author Response

Thank you very much for taking the time to review this manuscript. Please find the detailed responses in the attachment, the corresponding revisions/corrections highlighted/in track changes in the response and re-submitted files.

Author Response File: Author Response.docx