Understanding In Vivo Chromatic Aberrations in Pseudophakic Eyes Using on Bench and Computational Approaches

Round 1

Reviewer 1 Report

Vinas et al. compared various methods for LCA quantification in IOLs and compared them with patient-preformed measurements. The study provides important insight into the link between in vitro and in vivo LCA levels, which still requires more extensive research. Although the manuscript is well written and the data are adequately presented, some changes are necessary before this paper is considered for publication.

108-111: Please elaborate on the “fill in” approach and how it was “strategically used”. Could also a reference be added?

Figures are small, and of poor quality, so they’re not well readable even after zooming in. Could the authors improve this aspect?

At this point, it’s not clear to the reader what fig. 1b depicts. It looks like the 546nm curves from fig. 3 were put together. However, presenting them at this stage without an accurate description of where these results come from is somewhat confusing. Additionally, the legend is already given in the figure, so reiterating it in the caption seems redundant.   

214: Which model was used for the computational simulations? The authors referenced two papers, but it’s not clear which one was applied. If the two were combined, please specify what parameters were selected?

214: What was the LCA contribution of the computational model eye?

214-216: The authors assessed the “through-focus optical quality” of their four IOL models. Unfortunately, how it was done in the case of diffractive lenses wasn’t described. It’s surprising given the well-known limitations of ray-tracing software when it comes to simulating the behavior of diffractive optical elements. Thorough explanations of the methods should substantially expand this part.  

242-243: Please elaborate on this. How was it calibrated? What was the correction value found?

249-253: Here again, the authors mention a procedure to account for setup’s LCA. So, one may wonder whether a different approach was used in lines 242-3.

251-252: If I understand it correctly, only two multifocal IOLs were studied, and both had +20D. So, was the shift “plotted as a function of the nominal IOL power” only for two points?

Tab.1: M can stand for both multifocal and monofocal. Please write in full “multifocal” or and this to your abbreviations under the table

283-306: Is there a figure missing? The description indicates the reader should look for “L9” or “L16”, but they can nowhere be found. A couple of aberrations, such as AOTF and DM, were introduced (and aren’t used in the text later), which may also refer to a schematic setup drawing.

332-349: Some of this information is already presented in earlier manuscript parts. Consider shortening to avoid duplicating your descriptions.

Fig. 3: These data come from Zemax simulations, so the term “implantation” is rather confusing in this context.

393: Wasn’t far LCA lower in the monofocal IOLs? The text suggests the opposite.

394-396: This sentence isn’t very precise; please rephrase.

396-398: If the diffractive design is identical, a more negative LCA results from lower material dispersion of the hydrophilic multifocal lens.

Fig. 5-8: What statistic was used to assess “intersubject variability”?

Fig. 7 and 8: It’s not clear how the statistical difference between the subjective and computational (Zemax) results was calculated, given only a single value available for the latter approach. Please provide more details.  

510-512: It’s not clearly written. Please rephrase. 

Minor issues

4: “1,7.,”

23: “consisted on” > of

26: MTF should be spelled out in the abstract    

27: The decimal separator must be changed throughout the manuscript (including the figures)      

128: “fociin” ?

141: “raw” ?

160: “full” > fully

166: “the high order aberrations” > higher-order aberrations

180: “Poday” is it correct?

369-371: “Mono-Phobic” or “MIOL-Philic” ??

493: “it use is” > “its use is”

513: “through-focusthrough-focus” ?

568 “IOLS” > IOLs

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

The authors ought to consider the following:

1. The abstract has acronyms that are not defined. Abstracts are stand-alone items.
2. Why describe materials as either hydrophobic or hydrophilic when the crucial optical factors that delineate materials, in the context of this paper, are refractive indices & Abbe numbers?
3. Introduction is too long (4 pages), unfocused, meandering and at times difficult to interpret. For example, I have no idea what the authors are trying to tell me in the single sentence included lines 68-70. Authors should focus summarize and remove the superfluous.   
4. Title is misleading. Only 5 phakic eyes, from individuals less than half the age of the pseudophakes, were included. Why were age and gender matched cases not included?
5. Authors use data that has already been published. Do they have copyright clearance to include these data in this paper? Did the owners of the original data provide written consent for their usage?  
6. Investigators found some significant differences/similarities between theoretical computations, in vitro bench tests and in vivo tests on postsurgical cases. They should concentrate on a) likely reasons accounting for the differences b) what could, or should, be adjusted to reach closer agreement between the 3 and c) the repeatability of the in vivo data. 
7. Results, Discussion & Conclusion sections are too long. These sections should focus on the new and unexpected, and spare the interested reader from obvious statements such as ‘Different methods allow evaluating the theoretical optical quality with these designs, such as on bench measurements (real IOL in a cuvette) and computer eye model simulations (eye + IOL) using optical quality metrics.’
8. Authors wrote ‘Longitudinal chromatic aberration with multifocal diffractive designs can be generally explained using computational ray tracing and on bench measurements.’ This is not an earth-shattering discovery when you consider how much IOL companies design their products.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

This version is more coherent and easier to follow. However, I suggest the authors consider the following.

1) My initial 2^nd comment:

The authors agree with my comment but continue to describe materials as either hydrophobic or hydrophilic. The excuse being: for easier identification and commercial branding. The extent of hydrophilicity/hydrophobicity is irrelevant within the context of this study.  To remain objective and wholly scientific within the construct of the study: The materials should be identified by codes or optical characteristics in the run up to the discussion, not the hydrophilicity or hydrophobicity.

2) My initial 4^th comment:

Title has changed from ‘Chromatic aberration in phakic and pseudophakic eyes’ to ‘Explaining in vivo chromatic aberrations in pseudophakic eyes using on bench and computational approaches’

The authors say..’The goal of this study is to understand the chromatic through-focus performance of the diffractive designs of the evaluated IOLs, rather than a population study of chromatic aberration’

But that does not fit with the new title of the paper. The authors are attempting to understand an issue, but the title implies they wish to explain an issue to an audience that is not totally conversant with the said issue. The new title is an inaccurate description of content, or the content does not logically follow on from the new title. Are the authors trying to understand or explain?

3. Considering the current zeitgeist, is it necessary to include the word ‘native’ in line 42?

Author Response

Reviewer #2

This version is more coherent and easier to follow.

We are glad that the reviewer finds this version more coherent and easier to follow. We thank the reviewer for his/her additional comments; we have implemented them and we hope that the manuscript is ready for publication.

Specific comments

However, I suggest the authors consider the following.

1) My initial 2^nd comment: The authors agree with my comment but continue to describe materials as either hydrophobic or hydrophilic. The excuse being: for easier identification and commercial branding. The extent of hydrophilicity/hydrophobicity is irrelevant within the context of this study.  To remain objective and wholly scientific within the construct of the study: The materials should be identified by codes or optical characteristics in the run up to the discussion, not the hydrophilicity or hydrophobicity.

We considered the reviewer’s point and entertained various possibilities, none of which was deemed fully satisfactory. We opted by leaving the denomination hydrophilic / hydrophobic as this had been used in previous papers and therefore more relatable to published data. Besides, the differences in water uptake between materials largely determine the refractive index and Abbe number, key parameter in the LCA

2) My initial 4^th comment:

Title has changed from ‘Chromatic aberration in phakic and pseudophakic eyes’ to ‘Explaining in vivo chromatic aberrations in pseudophakic eyes using on bench and computational approaches’. The authors say..’The goal of this study is to understand the chromatic through-focus performance of the diffractive designs of the evaluated IOLs, rather than a population study of chromatic aberration’. But that does not fit with the new title of the paper. The authors are attempting to understand an issue, but the title implies they wish to explain an issue to an audience that is not totally conversant with the said issue. The new title is an inaccurate description of content, or the content does not logically follow on from the new title. Are the authors trying to understand or explain?

Following the reviewer’s comment we have Explaining by Understanding in the tittle.

3. Considering the current zeitgeist, is it necessary to include the word ‘native’ in line 42?

Following the reviewer’s comment we have replaced native by natural

Author Response File: Author Response.pdf