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. 2023 Aug 24;18(8):e0289033. doi: 10.1371/journal.pone.0289033

Effect of optional biometric parameters in the Kane formula on intraocular lens power calculation

Xiao-Yu Li 1,2, Xuan Liao 1,*, Jia Lin 1, Chang-Jun Lan 3, Qing-Qing Tan 1
Editor: Manuel Garza León4
PMCID: PMC10449110  PMID: 37616217

Abstract

Purpose

To investigate the effect of the optional biometric parameters lens thickness (LT) and center corneal thickness (CCT) in the Kane formula on intraocular lens (IOL) power calculation.

Methods

A cross-sectional study included consecutive cataract patients who received uncomplicated cataract surgery with IOL implantation from May to September 2022 were enrolled. The ocular biometric parameters were obtained using IOLMaster 700 and then inputted into online Kane formula calculator. The IOL power was calculated for targeting emmetropia and compared between groups: not omitting (NO) group, omitting LT and CCT (OLC) group, omitting LT (OL) group and omitting CCT (OC) group. Further, according to the axial length (AL), anterior chamber depth (ACD), and mean keratometry (Km), the eyes were divided into three subgroups, respectively.

Results

1005 eyes of 1005 consecutive patients were included. There was no significant difference in IOL power between NO group and OC group (P = 0.064), and the median absolute difference (MedAD) was 0.05D. The IOL power in NO group showed significant differences from OLC group and OL group respectively (P < 0.001), and both MedAD values were 0.18D. Among AL subgroups, MedAD ranged from 0.06D to 0.35D in short eyes. Among ACD subgroups, the above values ranged from 0.06D to 0.23D in shallow ACD subgroup. Among Km subgroups, these values ranged from 0.05D to 0.31D in steep Km subgroup.

Conclusion

The optional biometric parameter CCT has no effect on the calculation results of the Kane formula, whereas the parameter LT has a great influence on the Kane formula results for the IOL power calculation in cataract patients with short AL, shallow ACD and steep Km.

Introduction

The prediction accuracy of intraocular lens (IOL) refractive power has become the key to achieving good postoperative vision [1]. This also prompted the IOL power calculation formulas to update constantly, from the historical or refraction-based formulas, empirical formulas and vergence formulas, to the current artificial intelligence based formulas and ray tracing calculation formulas [2].

A large number of clinical studies have found that the Kane formula, a new generation of IOL calculation formula, was proved to be the most accurate formula in cataract patients with different axial length (AL) spectra [3–5]. Kane formula calculates IOL refractive power using biological sex (BS) and ocular biometric parameters, included AL, anterior chamber depth (ACD), keratometry readings (K), lens thickness (LT) and center corneal thickness (CCT). Although adding LT and CCT improves the prediction, they are set as optional variables. This allows the formula to be used in cases where LT and CCT measurements are not performed due to equipment limitations, thus broadening the application range of the formula.

There is still a lack of studies on the role of the optional biometric parameters in the Kane formula for IOL power calculation. This study aims to compare the IOL power calculation by selecting all biometric parameters or omitting optional biometric parameters in the Kane formula, so as to explore the influence of optional biometric parameters of the Kane formula on the IOL power calculation.

Materials and methods

Patients and groupings

A cross-sectional study included consecutive cataract patients who received uncomplicated cataract surgery with IOL implantation in the Affiliated Hospital of North Sichuan Medical College from May to September 2022. This study followed the Declaration of Helsinki and was approved by the Ethics Committee of the Affiliated Hospital of North Sichuan Medical College (2021ER151-1). The informed consents were signed. This study has been registered in the Chinese Clinical Trial Registry (ChiCTR2200059168).

Inclusion criteria were as follows: (1) patients with age-related cataract or high myopes with cataract, and Emery nuclear grade II ~ IV; (2) preoperative corneal astigmatism less than 2.0D; (3) uncomplicated cataract surgery and IOL implantation were performed; (4) complete preoperative data; (5) implantation of ZCB00 IOL (Advanced Medical Optics, USA). The exclusion criteria were: (1) patients who could not be measured by IOLMaster 700 (Carl Zeiss Meditec, Jena, Germany); (2) patients with any corneal diseases, such as keratoconus, pterygium, or corneal scarring of any etiology; (3) patients with fundus lesions; (4) patients with a history of ocular surgery or ocular trauma. If patients had underwent bilateral surgeries, only one eye included was chosen randomly.

Groups according to the biometric parameters were involved in the Kane formula: (1) not omitting (NO) group; (2) omitting LT and CCT (OLC) group; (3) omitting LT (OL) group; (4) omitting CCT (OC) group. Patients were subgrouped according to the preoperative biometric parameters measured by IOLMatser 700. According to Kane [6] AL classification method, eyes were divided into: short AL subgroup (AL ≤ 22.00mm), normal AL subgroup (22.00mm<AL<26.00mm), and long AL subgroup (AL ≥ 26.00mm). According to Hipolito [7] ACD classification method, eyes were divided into: shallow ACD subgroup (ACD ≤ 3.00mm), normal ACD subgroup (3.00mm < ACD < 3.50mm), and deep ACD subgroup (ACD ≥ 3.50mm). According to Kim [8] Km classification method, eyes were divided into: flat Km subgroup (Km ≤ 42.00D), normal Km subgroup (42.00D < Km < 46.00D), and steep Km subgroup (Km ≥ 46.00mm).

Examinations and surgical procedures

All patients underwent routine ophthalmic examination before surgery, including slit-lamp, best corrected visual acuity, intraocular pressure, corneal endothelium, B scan and fundus examination. A professional was assigned to measure ocular biometric parameters including AL, keratometry (K1 and K2), mean keratometry (Km), ACD, LT and CCT using a swept-source optical coherence tomography (SS-OCT) biometer IOLMaster 700 (software version 1.88). All scans were carried out through the macular fovea under fixation station, and measurements with exclamation marks or asterisks were eliminated. The patients were operated by a single senior surgeon. The uncomplicated phacoemulsification and IOL implantation were performed under topical anesthesia. Through a 2.4 mm temporal clear corneal incision, a 5.5 ~ 6.0 mm continuous curvilinear capsulorhexis was made followed by phacoemulsification, and an IOL was then implanted into the capsular bag.

The ocular biometric parameters were inputted into the online Kane formula calculator (https://www.iolformula.com/). Using the optimized A-constant for the Kane formula of 119.36 and targeting emmetropia, the IOL power were calculated and compared between different combinations of mandatory or alternative biometric parameters (LT and CCT). Calculation difference (CD) is the calculation result of IOL power in NO group minus the result in OLC group (or OC group or OL group). The percentage of eyes within ±0.25D of CD (POCD±0.25D) were calculated for each group. Absolute calculation difference (AD) is the absolute value of the difference of calculation result of IOL power in NO group minus the result in OLC group (or OC group or OL group), and the median absolute calculation difference (MedAD) is the median of them. The smaller the CD (or AD or MedAD) is, the larger value of POCD±0.25D will be, indicating that the optional biometric parameters have less influence on the accuracy of IOL power calculation.

Statistical analysis

SPSS 26.0 software was used for statistical analysis. Kolmogorov-Smirnov test was used to test the normality of the data. The data conforming to the normal distribution were represented by mean ± standard deviation (SD), while the skewed data were represented by median and quartile [M (Q1, Q3)]. Wilcoxon rank-sum test was used to compare the IOL power calculation results among groups. Kruskal-Wallis H test was performed to compare the values of AD among subgroups. Pearson’s Chi‑square test or Fisher’s exact test was used to compare the values of POCD±0.25D among subgroups. The difference was considered statistically significant if P value was less than 0.05. The sample size required for this study was calculated using PASS 15.0 software, with significance level of 0.05 and a power of 90%. According to the software calculation results, the total sample size of 532 eyes would be required. The total sample size of this study was 1005 cases, so it had a certain reference value for statistical treatment.

Results

A total of 1005 eyes (504 right and 501 left eyes) of 1005 consecutive patients (602 females and 403 males) were recruited and biometric parameters were presented in Table 1. The mean age of the patients was 65.36±11.10 years (ranged 30–91 years), the mean AL was 24.55±3.17 mm (ranged 20.09–35.00 mm), the mean Km was 44.14±1.51D (ranged 37.72–49.16 D), and the mean ACD was 3.03±0.50 mm (ranged 1.52–4.47 mm). The eyes were divided as follow: AL subgroups, including short (n = 228), normal (n = 527) and long (n = 250); ACD subgroups, including shallow (n = 473), normal (n = 339) and deep (n = 193); and Km subgroups, including flat (n = 72), normal (n = 821) and steep (n = 112).

Table 1. Ocular biometry data.

Mean ± SD Range
Age (years) 65.36±11.10 30.00–91.00
AL (mm) 24.55±3.17 20.09–35.00
K1 (D) 43.73±1.51 37.22–48.68
K2 (D) 44.54±1.54 38.22–49.67
Km (D) 44.14±1.51 37.72–49.16
ACD (mm) 3.03±0.50 1.52–4.47
LT (mm) 4.41±0.46 2.50–5.83
CCT (mm) 539.16±33.65 420.00–650.00
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AL, axial length; K1, flat keratometry; K2, steep keratometry; Km, mean keratometry; ACD, anterior chamber depth; LT, lens thickness; CCT, center corneal thickness.

The results of IOL power calculation in the NO group were compared with those in OLC group, OC group and OL group, as shown in Table 2 and Fig 1. There were no significant differences in IOL power between NO group and OC group (P = 0.064), and the value of MedAD was 0.05D. However, the IOL power of NO group was significantly different from OLC group and OL group respectively (P<0.001), and both MedAD values were 0.18D.

Table 2. AD values of OLC, OC and OL group compared to NO group.

Group Parameters Used AD [M (Q1, Q3)] (D) Z P
OLC BS、AL、K、ACD 0.18(0.08, 0.32) -15.443 < 0.001
OC BS、AL、K、ACD、LT 0.05(0.02, 0.08) -1.852 0.064
OL BS、AL、K、ACD、CCT 0.18(0.08, 0.32) -15.443 < 0.001
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BS, biological sex; AL, axial length; K, keratometry; ACD, anterior chamber depth; LT, lens thickness; CCT, center corneal thickness.

Fig 1. Box-plot of AD values of OLC group, OC group and OL group.

Fig 1

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The AD values based on AL subgroups were shown in Fig 2A and Table 3. The results showed that AD values of OLC group and OL group in patients with short eyes were highest, in which the MedAD values were both 0.35D. However, the AD values of the long eyes were lowest, and the MedAD values were 0.08D. There were no significant differences in the AD values of OC group among the AL subgroups (P = 0.119). The AD values of ACD subgroups were shown in Fig 2B and Table 4. The optional biometric parameters had the greatest influence on IOL power calculation in shallow ACD (MedAD ranged from 0.06D to 0.23D), while the optional biometric parameters had the least influence on deep ACD (MedAD ranged from 0.04D to 0.10D). The AD values of Km subgroups were shown in Fig 2C and Table 5. The results indicated that AD values of OLC group and OL group in the steep Km subgroup were highest, in which the MedAD values were both 0.31D, and the lowest MedAD values were 0.05D in flat Km subgroup. The differences of AD values in OC group among Km subgroups did not reach statistical significance (P = 0.518).

Fig 2. Box-plot of AD values in different optional parameter groups.

Fig 2

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(A, AL subgroups; B, ACD subgroups; C, Km subgroups).

Table 3. AD values and POCD±0.25D values in AL subgroups.

Short AL
(n = 228)		 Normal AL
(n = 527)		 Long AL
(n = 250)
AD [M (Q1, Q3)] (D) H P
OLC 0.35(0.19, 0.48) 0.18(0.09, 0.30) 0.08(0.04, 0.18) 197.883 a < 0.001
OC 0.06(0.03, 0.08) 0.05(0.03, 0.08) 0.04(0.02, 0.07) 4.262 a 0.119
OL 0.35(0.19, 0.48) 0.18(0.09, 0.30) 0.08(0.04, 0.18) 197.883 a < 0.001
POCD±0.25D χ 2 P
OLC 34.65% 67.17% 86.80% 144.980 b < 0.001
OC 97.37% 99.43% 100.00% 8.353 c 0.007
OL 34.65% 67.17% 86.80% 144.980 b < 0.001
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a Kruskal-Wallis H test

b Pearson’s Chi‑square test

c Fisher’s exact test.

Table 4. AD values and POCD±0.25D values in ACD subgroups.

Shallow ACD
(n = 473)		 Normal ACD
(n = 339)		 Deep ACD
(n = 193)
AD [M (Q1, Q3)] (D) H P
OLC 0.23(0.13, 0.39) 0.15(0.07, 0.28) 0.10(0.05, 0.21) 82.971 a < 0.001
OC 0.06(0.03, 0.09) 0.05(0.02, 0.07) 0.04(0.02, 0.06) 13.508 a < 0.001
OL 0.23(0.13, 0.39) 0.15(0.07, 0.28) 0.10(0.05, 0.21) 82.971 a < 0.001
POCD±0.25D χ 2 P
OLC 53.28% 70.80% 81.87% 57.422 b < 0.001
OC 98.31% 99.71% 100.00% 5.323 c 0.067
OL 53.28% 70.80% 81.87% 57.422 b < 0.001
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a Kruskal-Wallis H test

b Pearson’s Chi‑square test

c Fisher’s exact test.

Table 5. AD values and POCD±0.25D values in Km subgroups.

Flat Km
(n = 72)		 Normal Km (n = 821) Steep Km (n = 112)
AD [M (Q1, Q3)] (D) H P
OLC 0.13(0.07, 0.22) 0.18(0.08, 0.30) 0.31(0.14, 0.46) 28.261 a < 0.001
OC 0.05(0.02, 0.09) 0.05(0.02, 0.08) 0.05(0.02, 0.07) 1.317 a 0.518
OL 0.13(0.07, 0.22) 0.18(0.08, 0.30) 0.31(0.14, 0.46) 28.261 a < 0.001
POCD±0.25D χ 2 P
OLC 80.56% 66.14% 43.75% 30.183 b < 0.001
OC 98.61% 99.15% 99.11% 0.898 c 0.640
OL 80.56% 66.14% 43.75% 30.183 b < 0.001
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a Kruskal-Wallis H test

b Pearson’s Chi‑square test

c Fisher’s exact test.

In addition, the POCD±0.25D values among different subgroups were shown in Fig 3 and Tables 3–5. For AL, the POCD±0.25D values of the short-eye subgroup were lowest, in which the value was 97.37% in OC group, and 34.65% in both OLC and OL groups. However, the POCD±0.25D values of the long eyes were highest, which was 100% in OC group, and 86.80% in both OLC group and OL group. For ACD, the POCD±0.25D values of the shallow ACD subgroup were lowest, which were 53.28% in both OLC and OL group; The POCD±0.25D values of the deep ACD were highest, which were 81.87% in both OLC and OL group. For Km, the POCD±0.25D values of the steep ACD subgroup were lowest, which were 43.75% in both OLC and OL group; The POCD±0.25D values of the flat Km were highest, which were 80.56% in OLC group and OL group. Moreover, no significant differences were found in the POCD±0.25D values of OC group among the subgroups which were divided by ACD and Km (P = 0.067, 0.640, respectively).

Fig 3. Histogram of POCD±0.25D values in different optional parameter groups.

Fig 3

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(A, AL subgroups; B, ACD subgroups; C, Km subgroups).

Discussion

With the advances of IOL calculation formulas, the prediction accuracy hasgreatly improved. According to the number of preoperative biometric parameters, early IOL calculation formulas can be divided into 2-variable formulas (Hoffer Q [9], SRK/T [10] and Holladay 1 [11]) and 3-variable formulas (Haigis [12]). The 2-variable formula predicted the effective lens position (ELP) according to AL and K, while the 3-variable formula considered the effects of AL and preoperative ACD on ELP. The advent of optical coherence biometers provided the opportunity to measure ocular biometric parameters more precisely. The 5-variable formula (Barrett Universal II), 6-variable formula (Kane), and 7-variable formula (Holladay 2) have also appeared successively [13]. However, LT, CCT and white to white (WTW) are usually used as optional biometric parameters in the calculation formulas. Theoretically, more biometric parameters involved in the calculation of IOL power can provide more accurate results, and its calculation result will vary with the different biometric parameters involved. To our knowledge, this study is the first to evaluate the effect of optional biometric parameters in the Kane formula on IOL power calculation in different selections of AL, ACD and Km.

Kane formula is based on theoretical optics combines regression research with artificial intelligence technology, and uses efficient cloud-based algorithm to obtain calculation results with high accuracy [14]. The mandatory biometric parameters BS, AL, ACD, K and optional biometric parameters LT and CCT can be used to calculate the IOL refractive power. Although authors of the Kane formula suggested the convenience of using optional biometric parameters LT and CCT, the strategy of mandatory biometric parameters was widely used due to its high accuracy. Connell et al. [15] included 846 cataract patients implanted with SN60WF, and compared the accuracy of Kane, Hill-RBF, Olsen, BU II, Haigis, SRK/T, Hoffer Q, Holladay 1 and Holladay 2 formulas. The results showed that Kane formula had the highest accuracy among all patients when mandatory biometric parameters (BS, AL, ACD and K) were entered. However, when biometric instruments or ocular conditions were limited in clinical practice, only partial optional biometric parameters can be measured, which affects the calculation of IOL power.

Therefore, by comparing the IOL power results of the Kane formula when all biometric parameters were included with the results when biometric parameters were changed, this study found that there was no significant difference between NO group and OC group (P = 0.064), and MedAD value was 0.05D. The IOL power in NO group had significant differences with OLC group and OL group respectively (P<0.001), and the both MedAD values were 0.18D. Given this, LT plays an important role in the IOL power calculation of the Kane formula. It is speculated that the reason may be that the Kane formula takes into account the influence of ACD on postoperative ELP, and it is logical to assume that LT has a certain effect on ACD. Due to LT thickens with age, LT is usually negatively correlated with ACD, and the combination of LT and ACD can improve the prediction of postoperative ELP [16]. It is worth noting that the OLC group and the OL group have the same IOL power calculation results, that is, adding optional biometric parameter CCT alone has no effect on the calculation results of the Kane formula. Thus, it is necessary to calculate the IOL power combined with LT. Moreover, due to the artificial intelligence algorithm of the Kane formula itself, regression analysis of 30,000 eyes in the database may result in CCT as a predictor of insignificant importance.

In addition, this study further subgrouped subjects according to AL, ACD and Km, and explored the influence of optional biometric parameters of the Kane formula on IOL power calculation in each subgroup. The analysis showed that short AL, shallow ACD and steep Km had significant effects on the results of the Kane formula. Given that in these cases patients need high power IOL implantation, any little parameter change may have a great impact on the outcomes, and therefore the optional biometric parameters are particularly important for the calculation in the Kane formula. Moreover, these abnormal biometric parameters often have a great impact on the IOL power calculation and the prediction error occurs, so all biometric parameters should be considered to help improve the prediction accuracy of the Kane formula. Previous studies have also investigated the influence of optional biometric parameters of some formulas on IOL power calculation. Vega [17] continuously enrolled 501 cataract patients to evaluate the effect of optional biometric parameters of BU II formula on IOL power calculation. Their results showed that in short AL subgroup, there were significant clinical differences in the results of IOL power calculation between using partial biometric parameters and using all biometric parameters in BU II formula, while in normal AL subgroup and long AL subgroup, optional biometric parameters had little influence on IOL power calculation. Srivannaboon et al. [18] analyzed the influence of LT in Holladay 2 formula on the accuracy of IOL power calculation in 143 cataract patients, and found that there was no statistical difference in IOL power calculation results of Holladay 2 formula with and without LT in all AL subgroups. However, only 15 short eyes were included in the above study, and AL was measured by optical biometrics but LT was measured by ultrasound biometrics. Studies have found that the LT measured by optical biometrics and ultrasonic biometrics was not interchangeable, and the difference in measurement might affect the research results [19]. Thus, the results need to be further determined. In addition, Taroni et al. [20] conducted a study of 169 cataract patients and found that the use of the optional biometric parameter LT in Kane, BU II, EVO and RBF formula did not improve the accuracy of the calculation formula. However, a relatively small number of short eyes were included in his study, and no subgroup analysis was conducted for the short AL group.

There are still some limitations in this study: the sample size of the flat Km subgroup (n = 72) and the steep Km subgroup (n = 112) may still be insufficient to show statistical effects. Due to methodological limitations of this study, postoperative follow-up and refractive status data were not available. Therefore, further clinical studies are needed to evaluate the contribution of optional biometric parameters to the accuracy of the Kane formula.

In summary, the optional biometric parameter CCT has no effect on the calculation results of the Kane formula, whereas the optional biometric parameter LT has a great influence on cataract patients with short AL, shallow ACD and steep Km. Under these conditions, it is recommended that LT should be employed when using the Kane formula for IOL power calculation.

Supporting information

S1 Data

(XLSX)

Click here for additional data file. (203.7KB, xlsx)

Data Availability

All relevant data are within the paper and its Supporting Information files.

Funding Statement

Supported by the Project of the Strategic Cooperation of City and College (No. 22SXFWDF0003).The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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Decision Letter 0

Manuel Garza León

28 Apr 2023

PONE-D-23-03187Effect of optional biometric parameters in the Kane formula on intraocular lens power calculationPLOS ONE

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Reviewer #1: With the advances of IOL calculation formulas, the prediction accuracy has been greatly improved.Patients are also more demanding with refractive results.The cloud-based algorithm of Kane formula is perfect to make statistical more accurate calculations and enhance results .The more reliable data we can introduce , in any formula, not only Kane , the accurate the refractive results we will achieve .This is well known since Haigis Formulas , the first in the world to consider ACD and LENS thickness.CCT stills look at a parameter with no influence at all in any formula. The subgroup analisis that the authors have done in this paper is really clear and well developed.It finally shows what we all know about short eyes with small ACD and stepped K. The analysis showed that short AL, shallowACD and steep Km had significant effects on the results of the Kane formula and will do in any formula.The ELP looks better predictable in Kane formula but stills a great black hole in our practice . The only weakness of the article is the lack of follow up data and refractive status .

Reviewer #2: The study is very interesting and has a good sample size to corroborate its results. The results are valuable and important for clinical practice.

The necessary changes I consider are the following:

Review writing and spelling. Some commas are missing.

It does not state the number of patients in the subgroups. It would be worth creating a table that shows the values of each variable in each group with their distribution.

I suggest making a statistical comparison between the subgroups.

The study shows that the CCT has no effect on the iol calculation, but in the conclusions, it states that both optional parameters have an influence on the Kane formula. This conclusion is opposite to its results.

**********

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Reviewer #1: Yes: Maria Julia Zunino

Reviewer #2: No

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PLoS One. 2023 Aug 24;18(8):e0289033. doi: 10.1371/journal.pone.0289033.r002

Author response to Decision Letter 0

12 Jun 2023

Dear editor and reviewers,

Thanks for your efforts in reviewing our manuscript titled “Effect of optional biometric parameters in the Kane formula on intraocular lens power calculation” (ID: PONE-D-23-03187R1), and for providing many helpful comments and suggestions, which will all prove invaluable in the revision and improvement of our manuscript, as well as in guiding our research in the future.

We have studied your letter and the reviewers' comments point by point and revised the manuscript accordingly. The responses to the reviewer's comments are presented following. All authors have approved the response letter and the revised version of the manuscript.

Thank you again for your valuable comments and suggestions. We look forward to hearing from you soon in due course.

Yours sincerely,

Xuan Liao

Email: aleexand@163.com

Reviewer #1: With the advances of IOL calculation formulas, the prediction accuracy has been greatly improved. Patients are also more demanding with refractive results. The cloud-based algorithm of Kane formula is perfect to make statistical more accurate calculations and enhance results. The more reliable data we can introduce, in any formula, not only Kane , the accurate the refractive results we will achieve .This is well known since Haigis Formulas , the first in the world to consider ACD and LENS thickness. CCT stills look at a parameter with no influence at all in any formula. The subgroup analisis that the authors have done in this paper is really clear and well developed. It finally shows what we all know about short eyes with small ACD and stepped K. The analysis showed that short AL, shallow ACD and steep Km had significant effects on the results of the Kane formula and will do in any formula. The ELP looks better predictable in Kane formula but stills a great black hole in our practice. The only weakness of the article is the lack of follow up data and refractive status.

Response: Many thanks for your recognition and valuable advice. However, the present study aimed to compare the IOL power calculation results of Kane formula with all biometric parameters selected or optional biometric parameters omitted, to explore the influence of optional biometric parameters LT and CCT in the Kane formula on IOL power calculation. Due to methodological limitations of this study, postoperative follow-up and refractive status data were not available, so we unable to assess how the changes in IOL power calculation influenced the accuracy of the Kane formula.

Although investigating the accuracy of Kane's formula was beyond the scope of our study, there is no denying the importance of the reviewer's opinion that further clinical studies are needed to assess the contribution of optional biometric parameters to the accuracy of Kane's formula. This has been mentioned in the manuscript as a limitation of the present study.

Reviewer #2: The study is very interesting and has a good sample size to corroborate its results. The results are valuable and important for clinical practice. The necessary changes I consider are the following: 1. Review writing and spelling. Some commas are missing. 2. It does not state the number of patients in the subgroups. It would be worth creating a table that shows the values of each variable in each group with their distribution.

3. I suggest making a statistical comparison between the subgroups.

4. The study shows that the CCT has no effect on the iol calculation, but in the conclusions, it states that both optional parameters have an influence on the Kane formula. This conclusion is opposite to its results.

Responses:

1. Thanks for your suggestion and we have carefully reviewed the writing and spelling and added the missing commas in the revised manuscript.

2. We appreciate you pointing out this issue in our manuscript and have modified the manuscript accordingly. We have created tables to show the number of patients in the subgroups and the values of each variable in each group with their distribution. Please see tables 3-5.

3. We have made the changes to the manuscript to address this comment. We have conducted statistical comparison on these subgroups and created tables to display the results. Please see tables 3-5 and the results section of the manuscript. Many thanks.

4. Thank you for your careful checking. We have modified the conclusions to make them consistent with the results.

Attachment

Submitted filename: Response to Reviewers.docx

Click here for additional data file. (16.2KB, docx)

Decision Letter 1

Manuel Garza León

10 Jul 2023

Effect of optional biometric parameters in the Kane formula on intraocular lens power calculation

PONE-D-23-03187R1

Dear Dr. Liao,

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,

Manuel Garza León

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

Acceptance letter

Manuel Garza León

15 Aug 2023

PONE-D-23-03187R1

Effect of optional biometric parameters in the Kane formula on intraocular lens power calculation

Dear Dr. Liao:

I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department.

If your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. 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.

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on behalf of

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Academic Editor

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