Cataract in the Adult Eye Preferred Practice Pattern

Purpose To assess the accuracy of 7 intraocular lens (IOL) power formulas (Barrett Universal II, Haigis, Hoffer Q, Holladay 1, Holladay 2, SRK/T, and T2) using IOLMaster biometry and optimized lens constants. Setting Public hospital ophthalmology department. Design Retrospective case series. Methods Data from patients having uneventful cataract surgery with Acrysof IQ SN60WF IOL implantation over 5 years were obtained from the biometry and patient charts. Optimized lens constants were calculated for each formula and used to determine the predicted refractive outcome for each patient. This was compared with the actual refractive outcome to give the prediction error. Eyes were separated into subgroups based on axial length (AL) as follows: short (≤22.0 mm), medium (>22.0 to Results The study included 3241 patients. The Barrett Universal II formula had the lowest mean absolute prediction error over the entire AL range ( P P P P Conclusion In eyes with an AL longer than 22.0 mm, the Barrett Universal II formula was a more accurate predictor of actual postoperative refraction than the other formulas. Financial Disclosure None of the authors has a financial or proprietary interest in any material or method mentioned.

Intraocular lens power formula accuracy: Comparison of 7 formulas.

PURPOSE
To evaluate the accuracy of central corneal power measurements by Scheimpflug imaging (Pentacam) for eyes that had corneal refractive surgery.


METHODS
This study comprised two groups: a pilot group of 100 eyes with prior hyperopic or myopic LASIK that did not have cataract surgery, and a test group of 41 eyes with prior radial keratotomy (RK) and cataract surgery. In the pilot group, Pentacam images and refraction were taken preoperatively and 3 months after LASIK. The historical method was used to compute the theoretical postoperative keratometry (K) -reading and then compared to the measured equivalent K-reading (EKR) from the Pentacam. The EKR is the same value measured by standard keratometry or topography on the front surface, adjusted for the effect of the back surface power difference from normal. In the test group of RK eyes, the postoperative refraction and EKR were measured 3 months after cataract surgery. The Holladay IOL Consultant Program was used to back-calculate the theoretical K-reading. The EKR measurements were then compared to the back-calculated corneal power.


RESULTS
The optimal zone sample size was determined to be 4.5 mm for the pilot group. The mean prediction error for this group was -0.06+/-0.56 diopters (D) (range: -1.63 to +/-1.34 D). Using the 4.5-mm zone determined in the pilot group, the EKR value for the test group of 41 RK eyes had a mean prediction error of -0.04+/-0.94 D (range: -1.84 to +/-2.27 D).


CONCLUSIONS
When historical refractive data are not available, Scheimpflug imaging with the Pentacam provides an alternative method of measuring the central corneal power in eyes that previously received corneal refractive surgery.

Corneal Power Measurements Using Scheimpflug Imaging in Eyes With PriorCorneal Refractive Surgery

Multifocal and Extended Depth-of-Focus Intraocular Lenses in 2020.

Refractive Errors & Refractive Surgery Preferred Practice Pattern®.

Purpose To compare the accuracy of different methods that consider posterior corneal curvature in toric intraocular lens (IOL) calculations. Setting Ein-Tal Eye Center, Tel-Aviv, Israel. Design Retrospective comparative case series. Methods Consecutive cases of toric IOL implantation and preoperative measurements by optical biometry with optical low-coherence reflectometry (OLCR) (Lenstar LS 900) and a Scheimpflug camera (Pentacam) were retrospectively reviewed. Five methods of toric IOL calculation were compared as follows: (1) anterior corneal astigmatism using OLCR, (2) application of the Baylor nomogram, (3) posterior tomography combined with anterior corneal measurements using vector summation, (4) the Scheimpflug camera's true net power, and (5) total corneal refractive power. Toric IOL astigmatic power and axis, aiming for the lowest residual astigmatism, were selected according to these methods. Simulated residual refraction was calculated for each method based on manifest refraction and measured IOL alignment more than 3 weeks after surgery. Results The study included 115 eyes of 92 patients. The median simulated residual astigmatism was lower when based on vector summation of anterior and posterior astigmatisms than with calculations based on anterior corneal measurements only, application of the Baylor nomogram, true net power, and total corneal refractive power readings (0.49 diopters [D] versus 0.70 D, 0.60 D, 0.64 D, and 0.76 D, respectively) (P  Conclusions Residual astigmatism after toric IOL implantation can be reduced by appropriate consideration of the posterior corneal astigmatism. Using methods that take into account the effect of the posterior cornea in toric IOL calculations is suggested. Financial Disclosures Drs. Assia and Kleinmann are consultants to Hanita Lenses, Israel. Dr. Abulafia received a speaker's fee from Haag-Streit AG. No other author has a financial or proprietary interest in any material or method mentioned.

Effect of posterior corneal astigmatism on power calculation and alignment of toric intraocular lenses: Comparison of methodologies

Purpose To assess visual outcomes and patient satisfaction for trifocal and extended depth of focus (EDOF) intraocular lenses (IOLs) compared to monofocal IOLs with and without monovision. Methods Consecutive patients underwent bilateral cataract extraction surgery and implantation of either monofocal IOLs, monofocal IOLs using monovision, EDOF IOLs, or trifocal IOLs. Patients with preoperative biometric data, postoperative refraction, and visual acuity who completed a questionnaire regarding satisfaction and side effects were included. Visual outcome, spectacle independence, patient satisfaction, and subjective photic phenomena were assessed. Results Each group comprised 50 patients (100 eyes). The mean postoperative uncorrected distance, intermediate, and near visual acuities (logMAR) were: 0.17 ± 0.14 (Snellen 20/30), not applicable, and not applicable for monofocal; 0.08 ± 0.12 (Snellen 20/24), not applicable, and 0.07 ± 0.12 (Snellen 20/23) for monovision; 0.03 ± 0.08 (Snellen 20/21), 0.08 ± 0.12 (Snellen 20/24), and 0.23 ± 0.17 (Snellen 20/34) for EDOF; 0.07 ± 0.09 (Snellen 20/23), 0.08 ± 0.11 (Snellen 20/24), and 0.02 ± 0.06 (Snellen 20/21) for trifocal. Spectacle independence was reported by 36%, 70%, 74%, and 92% of patients, respectively. Postoperative halos and/or glare were experienced by 2%, 6%, 14%, and 38%, respectively, of which 2%, 0%, 6%, and 10%, respectively, were functionally disturbing. A total of 64%, 72%, 78%, and 76%, respectively, would choose the same IOL again. Conclusions Patient satisfaction rates were high in all groups. Trifocal IOLs were more effective in improving unaided whole range of vision, but were associated with a higher rate of photic phenomena. The EDOF IOL and monovision provided partial spectacle independence with less photic phenomena. [J Refract Surg. 2019;35(7):434-440.].

Visual Outcomes and Patient Satisfaction for Trifocal, Extended Depth of Focus and Monofocal Intraocular Lenses.

Background

To evaluate the accuracy of predicted refraction using multifocal intraocular lenses (IOLs) with power calculation based on two biometric devices and multiple IOL power calculation formulas.



Design

A retrospective study conducted in a private practice ophthalmology clinic.



Participants

Seventy-three eyes of 48 patients were evaluated.



Methods

Consecutive cases of eyes that had undergone successful cataract surgery with an implantation of a multifocal IOL (SN6AD1, Alcon Laboratories, Inc., Fort Worth, TX, USA) by a single surgeon were enrolled. Patients were meticulously screened for suitability for a multifocal IOL implantation according to our clinic guidelines. Two biometric measurement devices (IOLMaster-500 [Carl Zeiss Meditec AG, Jena, Germany] and Lenstar-LS900 [Haag-Streit AG, Koeniz, Switzerland]) were used under strict validation criteria to evaluate the predicted refraction errors for the Holladay 1, SRK/T, Hoffer Q, Haigis, Holladay 2, Barrett Universal II and Olsen formulas.



Main Outcome Measures

Predicted refractive sphere equivalent (RSE) errors.



Results

The measurements obtained from the two biometric devices were highly correlated. The standard deviation of the error in predicted RSE and the median absolute error were similar for the IOLMaster and the Lenstar devices using all formulas, ranging from 0.27 dioptres (D) to 0.31D and from 0.15D to 0.21D, respectively. A high percentage of eyes had an error in predicted RSE within ±0.5D from target refraction, ranging from 86.3% to 93.2%.



Conclusions

High accuracy can be achieved in multifocal IOL power calculations by appropriate patient selection, precise biometry and appropriate IOL calculation formulas.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/ceo.12478

Accuracy of predicted refraction with multifocal intraocular lenses using two biometry measurement devices and multiple intraocular lens power calculation formulas

Purpose To compare the accuracy of intraocular lens power prediction for eyes with average keratometry (K) readings greater than 46.00 diopters (D) and lower than 42.00 D. Setting Ein-Tal Eye Center, Tel-Aviv, Israel. Design Retrospective case series. Methods Eyes having cataract extraction surgery with steep and flat preoperative corneal curvatures determined with the Lenstar-LS900 device were enrolled. Refractive prediction errors for the Barrett Universal II, Haigis, Hill-RBF, Hoffer-Q, Holladay 1, Holladay 2, Olsen, and SRK/T formulas were compared. Optimized K values for the SRK/T formula were back-calculated for each group. Validation was performed using an additional dataset. Results The study comprised 171 eyes (79, K reading >46.00 D; 92, K reading Conclusions Power calculation for eyes with flat corneas and steep corneas requires the use of specific formulas for accurate postoperative results. An adjustment method of the SRK/T formula is proposed.

Intraocular lens power calculation for eyes with high and low average keratometry readings: Comparison between various formulas.

To compare ocular measurements of three optical biometry devices and their application in intraocular lens (IOL) power calculations. One hundred and forty eyes which had undergone cataract extraction surgery with preoperative biometry with OA­-2000, IOLMaster-500, and Lenstar-LS900 were enrolled. Biometry measurements of the three devices were compared. The deviation of the postoperative refraction from the preoperative refractive target was calculated with different formulas (Barrett Universal II, Hoffer Q, Holladay I, and SRK/T). Errors in the predicted astigmatism using the Barrett toric calculator were calculated for the toric IOLs. Additional 6465 eyes in which the IOLMaster-500 failed to measure axial length (AL) were reviewed. The percentage of successful measurements using the OA-2000 in those eyes was calculated. High agreement was found between the three devices for AL, anterior chamber depth, and average keratometry measurements (interclass correlation confidents: 1.000, 0.970, and 0.998, respectively, P < 0.001). The mean absolute prediction errors were similar using all formulas, ranging from 0.25 to 0.29 D, with no statistical significant difference between the three devices per each formula. The OA-2000 yielded a lower against-the-rule (ATR) centroid error in the predicted astigmatism than the IOLMaster-500 and Lenstar-LS900 (0.06 D ± 0.59 at 13.4° vs. 0.20 D ± 0.61 at 14.8° and 0.16 D ± 0.55 at 21.4°, respectively, P < 0.001, X-axis). Among 301 cases with unsuccessful AL readings using the IOLMaster-500, the OA-2000 had 284 (94.35%) successful measurements. The OA-2000 measurements showed good agreement with those of the IOLMaster-500 and Lenstar-LS900. Our results may suggest a potential advantage of the OA-2000 device in toric IOLs calculations and AL measurement success rate.

/pdf/accuracy-of-intraocular-lens-power-calculation-using-three-1e2w0rdw8u.pdf

Olga Reitblat

Papers

Effect of posterior corneal astigmatism on power calculation and alignment of toric intraocular lenses: Comparison of methodologies

Visual Outcomes and Patient Satisfaction for Trifocal, Extended Depth of Focus and Monofocal Intraocular Lenses.

Accuracy of predicted refraction with multifocal intraocular lenses using two biometry measurement devices and multiple intraocular lens power calculation formulas

Intraocular lens power calculation for eyes with high and low average keratometry readings: Comparison between various formulas.

Accuracy of intraocular lens power calculation using three optical biometry measurement devices: the OA-2000, Lenstar-LS900 and IOLMaster-500.