Calculation of Toric Intraocular Lens Power with the Barrett Calculator and Data from Three Keratometers

Aim. To investigate the interdevice agreement for differences in toric power calculated using data on anterior corneal astigmatism obtained with corneal topography/ray-tracing aberrometry (iTrace), partial coherence interferometry (IOLMaster 500), and Scheimpflug imaging (Pentacam). Methods. The analysis included 101 eyes (101 subjects) with regular astigmatism. The main outcome measures were corneal cylinder power, axis of astigmatism, and keratometry values. Toricity and toric IOL power were calculated using the online Barrett toric calculator. Interdevice agreement for measurement and calculation was assessed using a paired sample t-test and a nonparametric test. Results. Significant interdevice differences were noted in the magnitude of astigmatism and flat, steep, and mean keratometry values between iTrace and IOLMaster (all P < 0.01 ); in flat, steep, and mean keratometry values (all P < 0.001 ) but not in the magnitude of astigmatism ( P = 0.325 ) between iTrace and Pentacam; and in the magnitude of astigmatism and steep and mean keratometry values (all P < 0.01 ) but not in flat keratometry values ( P = 0.310 ) between IOLMaster and Pentacam. The toric IOL power calculated using data from the three devices showed the following trend: iTrace > IOLMaster (0.49 ± 0.36, P < 0.001 ) and Pentacam (0.39 ± 0.42, P < 0.001 ) and Pentacam was <IOLMaster (−0.10 ± 0.39, P = 0.009 ). There were differences in toricity calculated using data from the three devices ( P = 0.004 ). Conclusions. Differences in toric IOL power and toricity calculated using anterior keratometry data from iTrace, IOLMaster 500, and Pentacam should be noted in clinical practice.

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Resulting choice of toric intraocular lens using three devices and online Barrett calculator

10.21203/rs.3.rs-34869/v1 ◽

2020 ◽

Author(s):

jing dong ◽

yaqin zhang ◽

xiaogang wang

Keyword(s):

Intraocular Lens ◽

Nonparametric Test ◽

Partial Coherence ◽

Power Calculation ◽

Toric Iol ◽

Partial Coherence Interferometry ◽

Iol Power Calculation ◽

Scheimpflug Imaging ◽

Iol Power ◽

Clinic Practice

Abstract PURPOSE: To investigate interdevice agreement among toric power calculation difference based on corneal topography/ray-tracing aberrometry (iTrace), partial coherence interferometry (IOLMaster 500), and Scheimpflug imaging (Pentacam) for the measurement of anterior corneal astigmatism. METHODS: The analysis included 101 eyes with regular astigmatism of 101 subjects. The main outcome measures were corneal cylinder power, axis of astigmatism, keratometry values. The toric power and intraocular lens (IOL) power was calculated using online Barrett toric calculator. Interdevice measurement and calculation agreement was assessed using paired sample t-test, and nonparametric test. RESULTS: Significant interdevice difference existed for astigmatism magnitude, flat keratometry, steep keratometry and mean keratometry between iTrace and IOLMaster (all P < 0.01). Significant interdevice difference existed for flat keratometry, steep keratometry and mean keratometry (all P < 0.001) but not astigmatism magnitude (P = 0.325) between iTrace and Pentacam. Significant interdevice difference existed for astigmatism magnitude, steep keratometry and mean keratometry (all P < 0.01) but not flat keratometry (P = 0.310) between IOLMaster and Pentacam. For toric IOL power calculation, iTrace calculation was statistically higher than IOLMaster (0.49±0.36, P <0.001) and Pentacam (0.39±0.42, P <0.001). Moreover, Pentacam IOL power calculation was statistically lower than IOLMaster (-0.10±0.39, P =0.009). Toricity calculation difference was also existed among the three groups (P = 0.004).CONCLUSIONS: The toric IOL power and toricity calculation difference based on iTrace, IOLMaster 500, and Pentacam anterior keratometry data should be noticed in clinic practice.

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Comparison of accuracy of Partial Coherence Interferometry based Zeiss IOL Master 500 and Immersion Ultrasound [Ocuscan RXP] for intraocular lens power calculation

Asian Journal of Ophthalmology ◽

10.35119/asjoo.v14i4.154 ◽

2016 ◽

Vol 14 (4) ◽

Author(s):

Vijaya Pai ◽

Divya Shastri ◽

Asha Kamath

Keyword(s):

Intraocular Lens ◽

Refractive Error ◽

Partial Coherence ◽

Power Calculation ◽

Partial Coherence Interferometry ◽

Iol Power Calculation ◽

Intraocular Lens Power ◽

Iol Power ◽

Group B ◽

Lens Power

Aim: To compare accuracy of intraocular lens power (IOL) calculation using Partial coherence Interferometry based Carl Zeiss IOL master 500 and Immersion ultrasound (Alcon Ocuscan RXP). Methods: A prospective randomized study of patients who underwent clear corneal phacoemulsification with foldable (IOL) by a single surgeon, during the period September 2010 to 2012. Group A included those patients in whom IOL power calculation using Immersion ultrasound (Ocuscan RXP) was used. Group B included those patients in whom IOL power calculation using Partial coherence Interferometry based Zeiss IOL master was used. SRK T formula was used to calculate the IOL power in both the groups. Postoperative final refraction was done at 6 weeks. Unaided visual acuity and best corrected visual acuity was assessed. Postoperative refractive error was compared with predicted refractive error with each biometry method. Statistical analysis was done using SPSS 16.5. Continuous variables expressed as mean (standard deviation). P < 0.05 was considered significant.Results: There were 50 patients in Group A, 44 patients in Group B. Axial length of the patients varied from 22-26mm in both the groups. The postoperative refraction using Ocuscan, 88% had refractive error ≤± 0.5 D, 94% had ≤±1.00D, and 100% had ≤±2.0D of emmetropia. Using Zeiss IOL Master 72.7% had ≤± 0.5 D, 100% had ≤±1.00D of refractive error. Difference in absolute postoperative refractive error using Ocuscan vs. IOL Master was not statistically significant. Conclusion: In our study both ultrasound Ocuscan and IOL master were accurate in calculating intraocular lens power and achieving postoperative refraction closer to emmetropia.

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