Development and Clinical Accuracy of a New Intraocular Lens Power Formula (VRF) Compared to Other Formulas

Voytsekhivskyy, Oleksiy

doi:10.1016/j.ajo.2017.10.020

Cited by 39 publications

(27 citation statements)

References 22 publications

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“…It has been shown to be more accurate than the SRK/T.  VRF formula: this vergence formula, developed by Oleksiy Voytsekhivskyy, MD, is one of the few published ones (25). The IOL position is predicted from AL, K, ACD and CD.…”

Section: New Formulasmentioning

confidence: 99%

Recent developments in intraocular lens power calculation methods—update 2020

2020

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For many decades only a few formulas have been available to calculate the intraocular lens (IOL) power for patients undergoing cataract surgery: the Haigis, Hoffer Q, Holladay 1 and 2 and SRK/ T. In recent years, several new formulas for IOL power calculation have been introduced with the aim of improving the accuracy of refraction prediction in eyes undergoing cataract surgery. These include the Barrett Universal II, the Emmetropia Verifying Optical (EVO), the Kane, the Naeser 2, the Olsen, the Panacea, the Pearl DGS, the Radial Basis Function (RBF), the T2 and the VRF formulas. Although most of them are unpublished so that their structure is unknown, we give an overview of each formula and report the results of the studies that have compared them. Their performance in short and long eyes is provided and a special focus is given on the issue of segmented axial length, which is a promising method to obtain more accurate outcomes in short and long eyes. Here, the group refractive index originally developed for the IOLMaster may not represent the best method to convert the optical path length into a physical distance.The issue of posterior and total corneal astigmatism (TCA) is discussed in relation to toric IOLs; the latest formulas for toric IOLs and their results are also reported.

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Section: New Formulasmentioning

confidence: 99%

Recent developments in intraocular lens power calculation methods—update 2020

2020

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“…As an additional feature, a recently published VRF formula was used for all our IOL power calculations. This formula has been validated for an extensive range of axial lengths, and it is available as part of the ViOL Commander Software version 2.0.0.0 [ 38 ]. The most appropriate and suitable formula was chosen by the examiner depending on the parameters of the eye and personal experience.…”

Section: Methodsmentioning

confidence: 99%

The Impact of Changes in Corneal Back Surface Astigmatism on the Residual Astigmatic Refractive Error following Routine Uncomplicated Phacoemulsification

Tutchenko

Patel

Voytsekhivskyy

et al. 2020

Journal of Ophthalmology

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Purpose. To determine the significance of any association between intersessional changes in ocular residual astigmatism (RA) and astigmatism at corneal front (FSA) and back (BSA) surfaces following uneventful routine phacoemulsification. Methods. Astigmatism was evaluated by autorefractometry and subjective refraction and at both the corneal surfaces with Orbscan II™ (Bausch & Lomb) over central 3 mm and 5 mm optical zones at 1, 2, and 3 months after routine phacoemulsification in 103 patients implanted with monofocal nontoric intraocular lenses (IOLs, one eye/patient). Data were subjected to vector analysis to determine the actual change (Δ) in astigmatism (power and axis) for the refractive and Orbscan II findings. Results. The number of cases that attended where ΔRA was ≥0.50 DC between 1 and 2 months was 52 by autorefractometry and 36 by subjective refraction and between 2 and 3 months was 24 by autorefractometry and 19 by subjective refraction. Vector analysis revealed significant correlations between ΔFSA and ΔRA for data obtained by autorefractometry but not by subjective refraction. At all times, ΔBSA was greater than ΔFSA (p<0.01). Key findings for ΔBSA values over the central 3 mm zone were between (A) the sine of the axis of ΔRA (y) and sine of the axis of ΔBSA (x) for the data obtained by autorefractometry (between 1 and 2 months, y = 0.749 − 0.303x, r = 0.299, n = 52, p=0.031) and subjective refraction (between 2 and 3 months, y = 0.6614 − 0.4755x, r = 0.474, n = 19, p=0.040) and (B) ΔRA (y) and ΔBSA (x) powers between 2 and 3 months postoperatively for the data obtained by autorefractometry (ΔRA = 0.118 ΔBSA + 0.681 r = 0.467, n = 24, p=0.021) and subjective refraction (ΔRA = 0.072 ΔBSA + 0.545 r = 0.510, n = 19, p=0.026). Conclusion. Changes in the ocular residual refractive astigmatic error after implanting a monofocal nontoric IOL are associated with changes in astigmatism at the back surface of the cornea within the central optical zone.

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“…Formulas are classified based on the method used to determine IOL power and by the number of biometric variables used for calculation 9 . According to the method used, they are divided into two groups: using the principle of paraxial approximation or Gaussian optics and using the pathway of light in the optical system of the eye, also called geometric optics or ray optics 10 . Vergence-based IOL calculation formulas have traditionally been classified by generation from the first generation up to the fourth generation.…”

Section: Introductionmentioning

confidence: 99%

Refractive error with the Barrett True-K No History versus Panacea formula in cataract operated patients with a history of radial keratotomy

Mena-Linares¹,

Ponce-Martínez²,

Messina-Baas³

et al. 2021

HGMX

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Introduction:The challenge of calculating intraocular lens (IOL) power after refractive surgery such as radial keratotomy (RK) remains unresolved after two decades. At present, there is an increase in patients with this history. Objectives: The objectives of the study were to determine the difference in refractive error after surgery between the Barrett True-K No History and Panacea formulas, for the calculation of IOL in cataract operated patients with a history of RK. Materials and methods: An observational, analytical, cross-sectional, and retrospective study was conducted. The power of the IOL was calculated, with the Barrett True-K No History and Panacea formulas, and the IOLMaster 500 biometer. Two groups were studied. The predicted spherical equivalent was adjusted to obtain the power of the final implanted lens. The result of the predicted spherical equivalent was subtracted from the actual spherical equivalent, thus the refractive error was obtained for each formula. Student's t-test was used for independent groups. Results: The error with the Barrett True-K No History formula was −0.16 ± 1.12, whereas the error with the Panacea formula was −0.93 ± 1.22. p = 0.346. Conclusion: There was no statistically significant difference when comparing these two formulas, which showed that Panacea is as effective as Barrett True-K No History in cataract-operated patients with a history of RK.

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Development and Clinical Accuracy of a New Intraocular Lens Power Formula (VRF) Compared to Other Formulas

Cited by 39 publications

References 22 publications

Recent developments in intraocular lens power calculation methods—update 2020

Recent developments in intraocular lens power calculation methods—update 2020

The Impact of Changes in Corneal Back Surface Astigmatism on the Residual Astigmatic Refractive Error following Routine Uncomplicated Phacoemulsification

Refractive error with the Barrett True-K No History versus Panacea formula in cataract operated patients with a history of radial keratotomy

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