Evaluation of three biometric devices: ocular parameters and calculated intraocular lens power | Scientific Reports - Nature.com

Cataract surgery, successful which the opaque crystalline lens is replaced with an artificial intraocular lens (IOL), is 1 of the astir communal and palmy aesculapian procedures performed worldwide^1,2. Ocular biometric parameters are measured earlier country successful bid to cipher the optimal IOL for the idiosyncratic patient. The axial magnitude (AL) of the eye, anterior enclosure extent (ACD) and corneal curvature (K) measurements powerfully interaction the calculated IOL³. Accurate pre-operative biometric measurements are considered 1 of the astir important factors for palmy surgical result⁴, particularly with the improvement of toric and multifocal IOLs which necessitate the utmost surgical precision. As caller oregon updated biometric devices are brought into objective practice, it is important to thoroughly recognize their capabilities, statement with existing devices, and interaction connected IOL selection.

Swept-source optical coherence tomography (SS-OCT) is simply a non-invasive imaging modality that scans biologic structures astatine precocious resolution, velocity and sensitivity. The output measurement of scans enables three-dimensional investigation of the fixed structure⁵. Anterior conception OCT (ASOCT) scans the cornea, sclera and lens, thereby providing captious accusation for IOL enactment successful cataract surgeries. The Eyestar 900 (Haag Streit Diagnostics, Koeniz, Switzerland) and Anterion (Heidelberg Engineering, Heidelberg, Germany) are 2 precocious developed biometers based connected the SS-ASOCT technology. In contrast, the Pentacam corneal tomographer (Oculus Inc., Wetzlar, Germany) measures the K values utilizing a rotating Sheimpflug camera that acquires cross-sectional scans of the cornea⁶. In the clinic, erstwhile biometric devices neglect to nutrient K-readings owed to highly irregular corneas, corneal topography values are obtained and utilized to cipher the suggested IOL. While respective studies evaluating the ocular measurements person already shown bully repeatability and statement betwixt established biometers^7,8, differences successful circumstantial parameters specified arsenic anterior enclosure extent (ACD) and corneal curvatures (K) person been reported comparative to SS-ASOCT devices specified arsenic the IOLMaster 700 and corneal tomographers specified arsenic the Pentacam^9,10,11. Additionally, determination is constricted information successful the lit arsenic to whether these differences person immoderate objective impact, i.e., whether they impact the last enactment of IOL^12,13. The intent of this survey was truthful to comparison the ocular parameters measured by these 2 caller biometers to those measured by the IOLMaster 700 (Carl Zeiss Meditec, Jena, Germany), the archetypal SS-OCT-based biometric instrumentality and 1 of the astir commonly utilized devices for pre-cataract country measurements¹⁴. To further analyse the accuracy of SS-OCT corneal measurements, these values were besides compared to those obtained by the Pentacam (Oculus, Wetzlar, Germany) topographer. The last lens power calculations based connected the measurements of each biometric instrumentality were compared to analyse the objective impact.

This retrospective survey followed the tenants of the Helsinki declaration and was approved by the organization Helsinki Committee of Hadassah Medical Center (study fig HMO-0459-18). The committee exempts retrospective probe from informed consent by the participants. Data was collected from the Ophthalmology Department database and anonymized earlier analysis. Before biometric measurements, each subordinate underwent ophthalmic introspection including best-corrected ocular acuity (BCVA) with and without pinhole and afloat slit-lamp evaluation.

Ocular measurements

Identical ocular parameters were measured utilizing 3 antithetic ocular biometry devices: the The Eyestar 900 (Haag Streit Diagnostics, Koeniz, Switzerland), the Anterion (Heidelberg Engineering, Heidelberg, Germany) and the IOLMaster 700 (Carl Zeiss Meditec, Jena, Germany). The parameters compared were axial magnitude (AL), anterior enclosure extent (ACD), anterior corneal values (steep- and flat-K), cylinder (cyl) and axis. Additionally, K values were compared to those obtained by the Pentacam corneal tomographer (Oculus Inc., Wetzlar, Germany). Measurements successful each 4 devices were performed by optometrists with some the participants’ eyes unfastened during each measurement. In cases wherever much than 1 measurement was performed for a azygous subordinate utilizing the aforesaid instrument, lone the astir caller implicit measurement was included successful the last analysis.

The parameters included successful this survey person the top interaction connected IOL calculation. Therefore, successful bid to measure whether immoderate discrepancies betwixt the antithetic devices would effect successful differences successful the recommended IOL, the mean values of each parameter for each biometry instrumentality were entered successful the Barrett Universal II Formula¹⁵, Barrett Toric Calculator¹⁶ and Kane Formula ¹⁷ and the last IOLs were compared. Monofocal IOL formulas were utilized for eyes with little than 1.00 diopter (D) cylinder, and toric IOL formulas were utilized for eyes with ≥ 1.00D cylinder. Since corneal topographers are commonly utilized successful cases wherever biometers neglect to supply the K-values, specified arsenic precise steep oregon distorted corneas, IOL calculations were repeated with the Pentacam K-values substituting the antithetic biometers’ K-values successful bid to measure the interaction connected the last powerfulness of the suggested IOL.

Participants

All participants included successful this survey were cataract country candidates who presented astatine the session for modular biometric measurements earlier surgery. Excluded were participants nether property 40, with missing survey parameters, and/or whose ocular measurements had a modular deviation greater than 0.05 (mm oregon D). Participants were measured utilizing the Eyestar 900 and IOLMaster 700 (Group A) oregon the Anterion and IOLMaster 700 (Group B). A subset of each radical had corneal values measured besides with the Pentacam. Participants were besides stratified by magnitude of cylinder, with a cut-off level of 1.00D.

Sample size

Assuming mean implicit quality betwixt devices of 0.024 mm for AL with SD of 0.05 mm to the top quality successful mean measurements¹⁸, the minimal paired illustration size that is required is 73 eyes for each radical to execute a powerfulness of 80% and a level of value of 5%, 2 sided, utilizing the statulator illustration size calculator.

Statistical analysis

The normality of the information was confirmed utilizing the Shapiro–Wilk test. AL, ACD, flat- and steep-K, cylinder and axis were compared utilizing paired illustration t-test oregon Friedman test, according to the illustration size. Cohen's d was performed connected values that were importantly antithetic successful pairwise investigation successful bid to analyse effect size and objective significance. Correlation betwixt parameters measured by antithetic devices was evaluated with Pearson's coefficient. Mean values of AL, ACD and K’s of each instrumentality were utilized to cipher the recommended IOL by the Barrett Universal II Formula, Barrett Toric and the Kane calculators. IOL powerfulness was calculated utilizing the mean parameters of each biomter and stratified by instrumentality and magnitude of cylinder. Bland and Altman investigation was utilized to place systematic statement betwixt the measurements by the antithetic devices and to place outliers. Linear regression was utilized to measure the value of statement level betwixt biometry devices. The investigation was performed utilizing SPSS bundle (IBM SPSS Statistics, Version 27.0, Chicago. Armonk, NY: IBM Corp).

Ethical considerations

The organization Helsinki committee exempts retrospective probe from informed consent by the participants.

Patient characteristics

Records of 238 eyes (119 participants) were extracted from the Eyestar 900 and Anterion devices. This information was filtered for the existent survey based connected property and information completeness, resulting successful the exclusion of 42 eyes (17.6%). Ultimately, a full of 196 eyes (98 participants, 47.9% female, mean property 68.8 ± 9.7 years, scope 42–88 years) were included successful this study. Participants were divided to 2 groups: Group A consisted of 157 eyes (79 participants, 80.6%) measured with the Eyestar and IOLMaster, with 48 eyes (24.4%) besides measured by Pentacam. Group B consisted of 38 eyes (19 participants, 19.3%) measured with the Anterion and IOLMaster, with 22 eyes (11.2%) besides measured by Pentacam. Table 1 describes the demographic characteristics of the survey population.

Biometry results

In Group A determination was nary quality successful mean AL values erstwhile comparing the IOLMaster (24.22 ± 2.0 mm) to the Eyestar 900 (24.2 ± 2.04 mm; P = 0.79; Cohen’s d 0.009). Mean ACD was besides akin (3.34 ± 0.56 mm vs. 3.36 ± 0.56 mm, respectively; P = 0.09; Cohen’s d 0.03). No differences were recovered successful mean level and steep K values oregon successful cylinder axis (Table 2). A sub-group of 48 eyes successful Group A were besides measured utilizing the Pentacam. In this comparison, a quality was recovered successful mean steep K measurements betwixt the IOLMaster (45.02 ± 1.84D), the Eyestar (44.99 ± 1.85D) and the Pentacam (44.88 ± 1.76D) (P = 0.01). No differences were recovered successful mean level K values oregon successful cylinder axis (Table 2).

In Group B, mean AL values were antithetic erstwhile comparing the IOLMaster to the Anterion (23.68 ± 1.27 mm vs. 23.57 ± 1.27 mm, respectively; P = 0.006; Cohen’s d 0.08). Mean ACD was besides antithetic (3.27 ± 0.73 mm vs. 3.38 ± 0.78 mm; P = 0.04; Cohen’s d 0.14). No differences were recovered successful mean level and steep K values oregon successful cylinder axis (Table 3). A sub-group of 22 eyes successful Group B were besides measured utilizing the Pentacam. No important differences were recovered successful immoderate corneal parameter betwixt the IOMaster, Anterion and Pentacam (Table 3).

Analysis of correlations and agreements crossed devices

When investigating the correlations betwixt the antithetic devices, beardown correlations were recovered betwixt each 4 devices successful AL, ACD, level and steep K values and cylinder, ranging from R = 0.72 to 0.99. (Table 4) Comparison of cylinder axes betwixt the antithetic devices yielded weaker correlations, ranging from R = 0.32 to 0.95 (Table 4).

Bland and Altman investigation was performed successful bid to measure the statement betwixt the biometry devices. A preliminary investigation demonstrated nary quality betwixt the IOLMaster and Eyestar and truthful AL, ACD, and level and steep K values were each included successful the statement analysis. However, a quality betwixt the IOLMaster and Anterion successful mean AL and ACD values (P = 0.006, P = 0.04; respectively) was observed. Because these parameters did not amusement a utile level of agreement, determination were not included successful the Bland and Altman analysis.

When analyzing the linear regression enactment of the Bland and Altman scatter plot, IOLMaster and Eyestar values demonstrated nary quality of proportional bias of scatter dots supra and beneath the mean quality enactment for AL and level and steep K values (P = 0.54, P = 0.69, P = 0.21, respectively). These devices differed successful ACD values (P < 0.001), with a higher magnitude of ACD observations supra the mean quality line. IOLmaster and Anterion level and steep K plots were arsenic distributed supra and beneath the mean quality enactment (P = 0.23, P = 0.18, respectively) (Fig. 1).

Figure 1

Bland and Altman statement investigation of IOLMaster700, Eyestar900 and Anterion. Bland and Altman investigation of axial length, anterior enclosure extent and level and steep K successful the IOLMaster vs. the Eyestar (a–d), and level and steep K successful the IOLMaster vs. the Anterion (e,f). Axial magnitude and anterior enclosure extent are measured successful millimeters, and level and steep K successful diopters. (a ) No important quality betwixt IOLMaster and Eyestar scatter dots successful axial magnitude measurements, P = 0.54. (b) Significant quality betwixt IOLMaster and Eyestar scatter dots successful anterior enclosure extent measurements, P < 0.001. (c) No important quality betwixt IOLMaster and Eyestar scatter dots successful level K measurements, P = 0.69. (d) No important quality betwixt IOLMaster and Eyestar scatter dots successful steep K measurements, P = 0.21. (e) No important quality betwixt IOLMaster and Anterion scatter dots successful level K measurements, P = 0.23. (f) No important quality betwixt IOLMaster and Eyestar scatter dots successful steep K measurements, P = 0.18. D Diopters, ACD anterior enclosure depth, AL Axial length.

Effect of biometry measurements connected IOL powerfulness calculation

In bid to analyse whether the insignificant differences observed betwixt the devices impacted the suggested IOL power, the mean output values of each instrumentality (Tables 2 and 3) were inserted to the Barrett Universal II Formula, Barrett and Kane toric online calculators. Parameters were accordant betwixt calculators: Bausch & Lomb MX60 and MX60T lenses, A-Constant 119.15, surgical induced astigmatism (SIA) 0, people refraction plano, and incision determination astatine 100° for close oculus of each IOL calculation.

When comparing the IOLMaster and Eyestar (Group A) utilizing the Barrett toric calculator, the calculated IOLs were 18.50/2.00D and 19.00/2.00D, respectively. Using the Kane toric calculator, some IOLs were 19.00/2.25D. In Group B, examination of the IOLMaster and Anterion with the Barrett toric calculator yielded calculated IOLs of 19.50/2.75D and 20.00/2.75D, respectively, and with the Kane toric calculator 20.00/2.25D and 20.50/2.25D, respectively. It tin beryllium seen that the powerfulness of the suggested IOL based connected the Barrett toric calculator was 0.50D little successful the IOLMaster comparative to the Eyestar, but nary quality was recovered utilizing the Kane toric calculator. This aforesaid 0.50D quality was again recovered with some calculators erstwhile comparing the IOLMaster and Anterion. (Table 5) IOL calculation was past repeated with Pentacam K-values inserted successful spot of the K-values of each device. This resulted successful a accordant summation of 0.75D successful the cylinder powerfulness successful each biometers with some formulas (Table 5).

Table 6 describes the calculation of suggested IOL powerfulness stratified by magnitude of cylinder. The cut-off was 1.00D cylinder; eyes with < 1.00D were classified arsenic ‘low’ cylinder and monofocal IOL formulas were utilized to cipher the suggested IOL. Eyes with ≥ 1.00D cylinder were classified arsenic ‘moderate-high’ cylinder and toric IOL formulas were used. In the Group A debased cylinder eyes, it was recovered that each suggested monofocal IOLs were identical crossed some biometers and formulas. However, successful the moderate-high cylinder eyes, the aforesaid inclination observed successful the non-stratified calculation was again apparent, with the IOLMaster yielding a 0.50D little powerfulness successful the suggested IOL. In the Group B debased cylinder eyes, the suggested powerfulness was 0.50–1.00D little with the IOLMaster than the Anterion. In the moderate-high cylinder eyes, the suggested IOL powerfulness was 0.50D little with the IOLMaster than the Anterion erstwhile applying the Barrett toric calculator.

The superior purpose of this survey was to comparison ocular parameters measured by 3 caller biometers and measure the effects of immoderate quality connected the calculated IOL powerfulness for implantation successful cataract surgery. The biometers’ K-values were besides compared to K-values measured by a Scheimpflug-based corneal topographer.

When comparing AL and ACD measurements, a statistically important quality was recovered betwixt IOLMaster and Anterion but not betwixt the IOLMaster and Eyestar. However, Cohen’s d investigation demonstrated that these differences were not clinically significant, and each values were highly correlated. These results are successful enactment with caller findings by Fişuş and collaborators, which revealed discrepancies betwixt measurements of the Anterion and IOLMaster⁹. Similarly, Tañá-Rivero et et al. besides reported shorter ACD measurements with the IOLMaster comparative to the Anterion¹⁰. Like successful the existent study, the differences successful measurements were recovered to beryllium statistically important but were insignificant capable to astir apt beryllium clinically insignificant.

In summation to comparing betwixt the antithetic biometry devices, this survey besides compared K-readings of the 3 biometers to those of the Pentacam corneal topographer. There is objective value successful knowing the correlation betwixt the 2 modalities, due to the fact that biometers tin beryllium constricted successful their quality to nutrient K-readings successful cases of highly irregular corneas. In specified cases, these values are often extracted from a corneal topographer oregon keratometer. No differences were recovered successful the existent survey betwixt immoderate of the biometers successful level and steep K values oregon axes, yet erstwhile comparing these values to the Pentacam measurements, a statistically important quality was observed betwixt the IOLMaster, Eyestar and Pentacam successful steep K values. Interestingly, the level and steep K values were powerfully correlated betwixt each devices portion axis values demonstrated debased to mean correlations. Fişuş et al. did study important differences successful level and steep K values⁹, but this whitethorn beryllium owed to differences successful illustration size. This is supported by the results presented by Tañá-Rivero et al., which did not find important differences successful K-values and were based connected a illustration size akin to that of the existent study¹⁰. The substance of K axes has not yet been sufficiently studied and indispensable beryllium further investigated, arsenic close axis measurements are captious for palmy toric lens implantation.

In bid to found interchangeability of the devices, Bland and Altman investigation was performed. Our results indicated bully statement betwixt each 3 biometers connected astir parameters, with a insignificant offset successful ACD measurements betwixt the IOLMaster and the Eyestar. Although Fişuş et al. advised against utilizing the Anterion and IOLMaster interchangeably⁹, the deficiency of clinically important differences betwixt the devices leads america to suggest that these 2 devices tin beryllium utilized interchangeably, betwixt themselves arsenic good arsenic with the Eyestar.

An further facet of the superior purpose was to measure the objective interaction of the differences betwixt the devices. This was achieved by calculation of the suggested IOL powerfulness based connected the mean values of each device, and re-calculating with the substitution of Pentacam K-readings. Applying 2 commonly utilized IOL calculators to the full survey group, i.e., with nary stratification by cylinder amount, the IOLMaster tended to output a suggested IOL with 0.50D little powerfulness comparative to the Eyestar and Anterion. Tañá-Sanz et al. and Shetty et al. reported differences successful the calculated IOL betwixt the IOLMaster and Anterion which were statistically important but clinically insignificant^12,13. As the post-cataract country refractive targets suggested by the Royal College of Ophthalmology are wrong ± 1.00D for 85% of patients and wrong ± 0.50D for 55% of patients¹⁹, a quality of 0.50D tin beryllium viewed arsenic clinically insignificant. When Pentacam K-values were inserted into the IOL calculation, the cylinder powerfulness was consistently 0.75D higher crossed each biometric devices. As mentioned previously, successful a akin examination Tañá-Rivero et et al. did not find important differences successful the K-values, nevertheless this survey did not measure the effect connected the selected IOL¹⁰. In a systematic review, Kane and Chang¹⁸ besides recovered insignificant differences successful measured values and calculated IOL. However, they stress that portion devices whitethorn not disagree statistically successful the wide mean, they cannot beryllium considered interchangeable owed to the differences that tin hap successful the aforesaid oculus betwixt devices. Additionally, portion this reappraisal concludes that differences betwixt devices seldom impact the suggested IOL, determination is astir nary information connected the Eyestar and Anterion devices that were assessed successful the existent study.

Further calculations were performed connected sub-groups stratified by magnitude of cylinder. These analyses revealed differences betwixt devices of up to 1.00D successful the suggested IOL among the debased cylinder eyes. While inactive technically acceptable according to the Royal College of Ophthalmology guidelines¹⁹, successful an epoch wherever cataract surgeries tin beryllium considered refractive surgeries alternatively than conscionable rehabilitative procedures, it is captious to instrumentality enactment of these differences and execute further studies to validate this preliminary data.

This survey had respective limitations, chiefly owed to the retrospective survey plan which powerfully influenced the information disposable for investigation and caused constricted and unequal illustration sizes betwixt groups. Additionally, due to the fact that the survey was not built prospectively, galore viable measurements could not beryllium included successful the survey since the patients had lone undergone measurements by 1 biometric device. The Pentacam sub-groups and stratification by cylinder magnitude further constricted the illustration size, and truthful this information should beryllium viewed arsenic a preliminary ground for further research. It is worthy noting that the IOLMaster and Pentacam were accordant successful their biases comparative to different devices successful the suggested IOL power, contempt the constricted illustration group. The main spot of this study, however, is the examination of 3 biometry devices, 2 of which are rather caller with constricted information successful the literature. Moreover, the examination of corneal measurements betwixt SS-OCT devices and a Scheimpflug-based instrumentality further validates some technologies and besides provides a prime appraisal of these devices arsenic good arsenic objective impact.

In conclusion, each 3 biometers compared successful this survey demonstrated beardown statement successful their idiosyncratic parameters, with corneal measurements correlating good to the Pentacam. However, it is important to enactment that the Eyestar was much akin to the IOLMaster successful some AL and ACD, which are captious features successful IOL calculation. Additionally, the devices differed successful the suggested IOL, peculiarly erstwhile looking astatine calculations based connected K-values taken from a corneal topographer, and erstwhile the survey radical was divided to debased and moderate-high cylinder sub-groups. While these differences whitethorn not technically beryllium considered clinically significant, they are worthy information arsenic the satellite progresses towards minimal residual post-operative refraction. Further probe is required successful bid to measure the objective interaction connected post-cataract country patients.

References

Authors and Affiliations

1. Department of Ophthalmology, Hadassah Hebrew University Medical Center, Jerusalem, Israel

   Rivkah Lender, Devora Mirsky, Riki Greenberger, Zipora Boim, Lee Ben-Yaakov, Chaya Kashtan, Ibrahim Naffar, Shira Shine, Itay Chowers & Hadas Ben-Eli

2. Department of Optometry and Vision Science, Hadassah Academic College, Jerusalem, Israel

   Hadas Ben-Eli

Contributions

R.L. and H.B. wrote the main manuscript text. H.B. performed the statistical investigation and R.L. prepared the figures and tables. R.G., Z.B., L.B., I.N. and S.S. operated the instruments and performed the measurements. D.M. and C.K. collected the information and performed information entry. I.C. provided the plan of the survey and reviewed the manuscript.

Corresponding author

Correspondence to Hadas Ben-Eli.

Competing interests

The authors state nary competing interests.

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