Effect on refractive outcomes after cataract surgery of intraocular lens constant personalization using the Haigis formula

Comparison of the Optimized Intraocular Lens Constants Calculated by Automated and Manifest Refraction for Korean

Purpose: To derive the optimized intraocular lens (IOL) constants from automated and manifest refraction after cataract surgery in Korean patients, and to evaluate whether there is a difference in optimized IOL constants according to the refraction method.Methods: This retrospective multicenter cohort study enrolled 4,103 eyes of 4,103 patients who underwent phacoemulsification and in-the-bag IOL implantation at 18 institutes. Optimized IOL constants for the SRK/T, Holladay, Hoffer Q, and Haigis formulas were calculated via autorefraction or manifest refraction of samples using the same biometry and IOL. The IOL constants derived from autorefraction and manifest refraction were compared.Results: Of the 4,103 eyes, the majority (62.9%) were measured with an IOLMaster 500 followed by an IOLMaster 700 (15.2%). A total of 33 types of IOLs were used, and the Tecnis ZCB00 was the most frequently used (53.0%). There was no statistically significant difference in IOL constants derived from autorefraction and manifest refraction when IOL constants were optimized with a large number of study subjects. On the other hand, optimized IOL constants derived from autorefraction were significantly smaller than those from manifest refraction when the number of subjects was small.Conclusions: It became possible to use the IOL constants optimized from Koreans to calculate the IOL power. However, if the IOL constant is optimized using autorefraction in a small sample group, the IOL constant tends to be small, which may lead to refractive error after surgery.

Intraocular lens bicylindric power calculation method: Using both flat and steep K readings to improve intraocular lens power prediction

PURPOSE

To compare and analyze the accuracy of the refractive outcomes obtained in intraocular lens power calculation using the classical calculation method with mean keratometry (K) and the calculation method with both K meridians presented in this article.

METHODS

A total of 62 eyes of 62 subjects who were undergoing cataract surgery were included in this study. Optical biometry was performed using mean K and Haigis formula for classical intraocular lens calculation methods to achieve intraocular lens power; 4 weeks after surgery, prior to medical discharge, subjective refraction was made. Alternatively, intraocular lens power was calculated with bicylindric method using both keratometry readings, obtaining spherocylindrical refractive expected outcomes. Finally, results obtained with intraocular lens calculation methods, bicylindric method, and Haigis formula were compared.

RESULTS

Spherical equivalent calculated by classical intraocular lens calculation methods using Haigis formula (H-SE) was -0.027 ± 0.115 D and using bicylindric method (B-SE) was -0.080 ± 0.222 D. Achieved spherical equivalent obtained 4 weeks after surgery (A-SE) was -0.144 ± 0.268 D. Difference between H-SE and A-SE was -0.117 D (p = 0.002). Difference between B-SE and A-SE was not significant (-0.054 D, p = 0.109). Analysis in refraction groups showed a positive correlation between A-SE confronted to B-SE and H-SE (r = 0.313; p = 0.013 and r = 0.562; p < 0.001, respectively). This indicated a reliability in ametropic group prediction of 0.767 in H-SE and 0.843 in B-SE.

CONCLUSION

Intraocular lens calculation with bicylindric method could be more accurate and had more reliability than classical intraocular lens calculation method. Bicylindric method adds astigmatism control and provides a reliable expected spherocylindrical refraction.

Clinical comparison of a new swept-source optical coherence tomography-based optical biometer and a time-domain optical coherence tomography-based optical biometer

PURPOSE

To evaluate the repeatability and reproducibility of a newer swept-source optical biometer and to compare it with a standard partial coherence interferometry (PCI) biometer.

SETTING

Siriraj Hospital, Mahidol University, Bangkok, Thailand.

DESIGN

Prospective comparative study.

METHODS

One hundred eyes from 100 cataract patients were enrolled in this study. Each patient was measured with 2 optical biometers, a newer swept-source optical biometer (IOLMaster 700) and a standard partial coherence interferometry biometer (IOLMaster 500) by 2 independent operators. The keratometry, axial length (AL), anterior chamber depth, white-to-white corneal diameter, and intraocular lens (IOL) power, calculated by the SRK/T and the Haigis formulas for each device, were recorded. Intraoperator repeatability and interoperator reproducibility of both devices were analyzed using intraclass correlation coefficients (ICCs). Agreement of ocular biometry and IOL power between the 2 devices was evaluated using the Bland-Altman method.

RESULTS

The repeatability and reproducibility of the swept-source and standard biometers were high for all ocular biometry parameters (ICC, 0.93-1.00). The agreement between the 2 biometers was also high (ICC, 0.92-1.00). The IOL powers obtained from both devices were not distinct. Because of the density of the cataracts, the AL in 5 eyes could be measured only by the swept-source biometer.

CONCLUSIONS

Repeatability and reproducibility of a swept-source optical biometer was excellent and agreement with a standard biometer was very high. Better lens penetration ability and AL measurements were obtained with the swept-source biometer than with the standard biometer.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Influence of corneal asphericity on the refractive outcome of intraocular lens implantation in cataract surgery

PURPOSE

To evaluate the possible influence of anterior corneal surface asphericity on the refractive outcomes in eyes having intraocular lens (IOL) implantation after cataract surgery.

SETTING

Fondazione G.B. Bietti IRCCS, Rome, Italy.

DESIGN

Retrospective comparative case series.

METHODS

Intraocular lens power was calculated using the Haigis, Hoffer Q, Holladay 1, and SRK/T formulas. Asphericity (Q-value) was measured at 8.0 mm with a Placido-disk corneal topographer (Keratron), a rotating Scheimpflug camera (Pentacam), and a rotating Scheimpflug camera combined with Placido-disk corneal topography (Sirius). The relationship between the error in refraction prediction (ie, difference between expected refraction and refraction measured 1 month after surgery) and the Q-value was assessed by linear regression.

RESULTS

The same IOL model (Acrysof SA60AT) was implanted in 115 eyes of 115 consecutive patients. Regression analysis showed a statistically significant relationship between the error in refraction prediction and the Q-value with all formulas and all devices. In all cases, a more negative Q-value (prolate cornea) was associated with a myopic outcome, whereas a more positive Q-value (oblate cornea) was associated with a hyperopic outcome. The highest coefficient of determination was detected between the Hoffer Q formula and the Placido-disk corneal topographer (R(2) = 0.2630), for which the error in refraction prediction (y) was related to the Q-value (x) according to the formula y = -0.2641 + 1.4589 × x.

CONCLUSION

Corneal asphericity influences the refractive outcomes of IOL implantation and should be taken into consideration when using third-generation IOL power formulas.

FINANCIAL DISCLOSURE

Dr. Hoffer receives book royalties from Slack, Inc., Thorofare, New Jersey, and formula royalties from all manufacturers using the Hoffer Q formula. No other author has a financial or proprietary interest in any material or method mentioned.

Gender differences in refractive prediction in refractive lens exchange surgery

PURPOSE

To compare the refractive outcomes after refractive lens exchange (RLE) surgery with regards to gender and intraocular lens (IOL) power calculation formula.

METHODS

A cohort of consecutive patients operated with bilateral same-day RLE surgery at a private eye clinic (n = 512) was studied. Target refraction was emmetropia in all cases and Haigis formula was used for all IOL power calculations. One month after surgery, subjective refraction was assessed and the absolute refractive prediction error (RPEAbs), as well as the refractive prediction error with correct signs (RPESign), was calculated, as were the refractive outcomes with the SRK/T formula.

RESULTS

For the whole cohort, the Haigis formula rendered a significantly smaller RPEAbs than the SRK/T formula (0.16 ± 0.26 D vs 0.32 ± 0.30 D; p&lt;0.001). No gender difference in RPEAbs was seen. A slight myopic error was seen with the SRK/T formula in women, and a slight hyperopic error in men (-0.06 ± 0.47 D vs + 0.16 ± 0.39 D; p&lt;0.001). No similar gender difference was seen with the Haigis formula (+0.05 ± 0.29 D vs +0.05 ± 0.31 D; p = NS). Axial length, anterior chamber depth, and corneal steepness differed significantly between the sexes.

CONCLUSIONS

The Haigis formula generally performed better in this RLE cohort. The SRK/T formula generates a small myopic error in women and a hyperopic error in men, associated with flatter corneas, longer axial lengths, and deeper anterior chambers in the latter.

Optical biometry intraocular lens power calculation using different formulas in patients with different axial lengths

AIM

: To investigate the predictability of intraocular lens (IOL) power calculation using the IOLMaster and different IOL power calculation formulas in eyes with various axial length (AL).

METHODS

: Patients were included who underwent uneventful phacoemulsification with IOL implantation in the Department of Ophthalmology, Far Eastern Memorial Hospital, Taipei, Taiwan, China from February 2007 to January 2009. Preoperative AL and keratometric values (Ks) were measured by IOLMaster optical biometry. Patients were divided into 3 groups based on AL less than 22mm (Group 1), 22-26mm (Group 2), and more than 26mm (Group 3). The power of the implanted IOL was used to calculate the predicted postoperative spherical equivalence (SE) by various formulas: the Haigis, Hoffer Q, Holladay 1, and SRK/T. The predictive accuracy of each formula was analyzed by comparing the difference between the actual and predicted postoperative SE (MedAE, median absolute error). All the patients had follow-up periods exceeding 3 months.

RESULTS

: Totally, there were 200 eyes (33 eyes in Group 1, 92 eyes in Group 2, 75 eyes in Group 3). In all patients, the Haigis had the significantly lower MedAE generated by the other formulas (P<0.05). In Group 1 to 3, the MedAE calculated by the Haigis was either significantly lower or comparable to those calculated by the other formulas.

CONCLUSION

: Compared with other formulas using IOLMaster biometric data, the Haigis formula yields superior refractive results in eyes with various AL.

Optimization of intraocular lens constant improves refractive outcomes in combined endothelial keratoplasty and cataract surgery

PURPOSE

To evaluate the accuracy of intraocular lens (IOL) power calculations with A-constant optimization in Descemet's stripping automated endothelial keratoplasty (DSAEK) combined with cataract extraction and intraocular lens implantation (DSAEK triple procedure).

DESIGN

Retrospective case series.

PARTICIPANTS

Thirty eyes of 22 patients with Fuchs' endothelial dystrophy who underwent the DSAEK triple procedure performed by a single surgeon.

METHODS

Prediction errors were calculated retrospectively for consecutive DSAEK triple procedures. These prediction errors then were used to determine an IOL constant for this cohort of patients. The new optimized IOL constant subsequently was compared with the manufacturer's IOL constant, allowing evaluation and quantification of refractive benefits of optimization.

MAIN OUTCOMES MEASURES

The error in diopters (D) of the predicted refraction with the manufacturer's and optimized IOL constants.

RESULTS

Optimization of the A constant decreased the mean absolute error (MAE) from 1.09 ± 0.63 D (range, 0.12-2.41 D) to 0.61 ± 0.4 D (range, 0-1.58 D; P = 0.004). Comparing the intended and final postoperative refractions calculated with the original manufacturer's constant and the optimized constant, 20% versus 43% of all eyes were in the less than 0.5-D range and 50% versus 83% of all eyes were in the less than 1.0-D range of the target refraction. Furthermore, optimization decreased the number of eyes that were more than 1.0 D from the target refraction from 50% to 17%.

CONCLUSIONS

Optimization of the IOL constant showed significantly improved accuracy of predicted postoperative refraction compared with the manufacturer's IOL constant, which may help improve the postoperative refractive outcomes in patients undergoing the DSAEK triple procedure.

Comparison of postoperative refractive outcomes: IOLMaster® versus immersion ultrasound

BACKGROUND AND OBJECTIVE

To compare the postoperative refractive outcomes between IOLMaster biometry (Carl Zeiss Meditec, Inc., Dublin, CA) and immersion ultrasound biometry for axial length measurements.

PATIENTS AND METHODS

Refractive outcomes in 354 eyes were compared using the IOLMaster and the immersion ultrasound biometry. Predicted refraction was determined using manual keratometry and the SRK-T formula with personalized A-constant.

RESULTS

The axial lengths measured using the IOLMaster and immersion ultrasound were 24.49 ± 2.11 and 24.46 ± 2.11 mm, respectively, and the difference was significant (P < .05). The mean errors were 0.000 ± 0.578 D with the IOLMaster, and 0.000 ± 0.599 D with the immersion ultrasound, but the difference was not significant. The mean absolute error was smaller with the IOLMaster than with immersion ultrasound (0.463 ± 0.341 vs 0.479 ± 0.359 D), but the difference was not significant.

CONCLUSION

IOLMaster biometry yields highly accurate results in cataract surgery. However, if the IOLMaster is unavailable, immersion ultrasound biometry with personalized intraocular lens constants is an acceptable alternative.

Accuracy of intraocular lens power calculations in eyes with axial length <22.00 mm

BACKGROUND

To assess the accuracy of Haigis, Holladay 1, Hoffer Q and SRK/T formulae in eyes with axial length of <22.00 mm.

DESIGN

Retrospective comparative analysis.

PARTICIPANTS

163 eyes of 97 patients undergoing phacoemulsification and intraocular lens (IOL) implantation.

METHODS

Ocular biometry was performed using IOLMaster laser interferometry. Predicted refractive outcomes before and after lens constant adjustment were compared to actual refractive outcomes.

MAIN OUTCOME MEASURES

Mean prediction (ME) and mean absolute errors (MAE) with standard deviations (±SD).

RESULTS

Mean preoperative spherical equivalent was +5.44D ± 1.97D. Mean axial length was 21.20 mm ± 0.60 mm. Using standard IOL constants the MAE for Hoffer Q (0.62D, ±0.52D) and Holladay 1 (0.66D ± 0.52D) were significantly lower than SRK/T (MAE 0.91D ± 0.64D; P = <0.0005 and P = 0.001 respectively), but not Haigis (MAE 0.82D ± 0.83D, P = 0.071 and 0.22 respectively). MAEs for all formulae were significantly reduced by IOL constant adjustment (all P = <0.001). Following this there was no statistically significant difference in MAEs between formulae (range 0.50-0.57D, P = 0.57). Increasing MAE was significantly associated with reducing axial length and increasing IOL power for all formulae. For bilateral cases, prediction errors between eyes were significantly correlated across all formulae (all P = <0.0001) and explained 32-42% of the variance in prediction error between eyes.

CONCLUSIONS

Prediction of postoperative refraction in patients with short axial lengths is challenging and at the limit of current, popular IOL formulae. There is now a clear need for prospective studies to assess latest generation IOL formulae such as Holladay 2 or Olsen in small eyes.

Comparison of intraocular lens power prediction using immersion ultrasound and optical biometry with and without formula optimization

PURPOSE

Comparison of postoperative refraction results using ultrasound biometry with closed immersion shell and optical biometry.

PATIENTS AND METHOD

Three hundred and sixty-four eyes of 306 patients (age: 70.6 ± 12.8 years) underwent cataract surgery where intraocular lenses calculated by SRK/T formula were implanted. In 159 cases immersion ultrasonic biometry, in 205 eyes optical biometry was used. Differences between predicted and actual postoperative refractions were calculated both prior to and after optimization with the SRK/T formula, after which we analysed the similar data in the case of Holladay, Haigis, and Hoffer-Q formulas. Mean absolute error (MAE) and the percentage rate of patients within ±0.5 and ±1.0 D difference in the predicted error were calculated with these four formulas.

RESULTS

MAE was 0.5-0.7 D in cases of both methods with SRK/T, Holladay, and Hoffer-Q formula, but higher with Haigis formula. With no optimization, 60-65 % of the patients were under 0.5 D error in the immersion group (except for Haigis formula). Using the optical method, this value was slightly higher (62-67 %), however, in this case, Haigis formula also did not perform so well (45 %). Refraction results significantly improved with Holladay, Hoffer-Q, and Haigis formulas in both groups. The rate of patients under 0.5 D error increased to 65 % by the immersion technique, and up to 80 % by the optical one.

CONCLUSIONS

According to our results, optical biometry offers only slightly better outcomes compared to those of immersion shell with no optimized formulas. However, in case of new generation formulas with both methods, the optimization of IOL-constants give significantly better results.

Clinically relevant biometry

PURPOSE OF REVIEW

Obtaining precise postoperative target refraction is of utmost importance in today's modern cataract and refractive surgery. Given the growing number of patients undergoing premium intraocular lens (IOL) implantations, patient expectation continues to rise. In order to meet heightened patient expectations, it is crucial to pay utmost attention to patient selection, accurate keratometry and biometry readings, as well as to the application of correct IOL power formula with optimized lens constants. This article reviews recent advances in the field of clinical biometry and IOL power calculations.

RECENT FINDINGS

Recently developed low-coherence reflectometry optical biometry is comparable to older ultrasonic biometric and keratometric techniques. In addition, the new IOLMaster software upgrade has improved reproducibility and enhanced signal acquisition. Further, the modern lens power formulas currently determine the effective lens position and the shape of the intraocular lens power prediction curve more accurately.

SUMMARY

In order to reach target refraction, precise biometric measurements are imperative. Understanding the strengths and limitations of the currently available biometry devices allows prevention of high variability and inaccuracy, ultimately determining the refractive outcomes.

Accuracy of intraocular lens power calculation formulas in primary angle closure glaucoma

Purpose

To compare the accuracy of intraocular lens (IOL) power calculation formulas in eyes with primary angle closure glaucoma (ACG).

Methods

This retrospective study compared the refractive outcomes of 63 eyes with primary ACG with the results of 93 eyes with normal open angles undergoing uneventful cataract surgery. Anterior segment biometry including anterior chamber depth, axial length, and anterior chamber depth to axial length ratio were compared by the IOL Master. Third generation formulas (Hoffer Q and SRK/T) and a fourth generation formula (Haigis) were used to predict IOL powers in both groups. The predictive accuracy of the formulas was analyzed by comparison of the mean error and the mean absolute error (MAE).

Results

In ACG patients, anterior chamber depth and the anterior chamber depth to axial length ratio were smaller than normal controls (all p < 0.05). The MAEs from the ACG group were larger than that from the control group in the Haigis formula. The mean absolute error from the Haigis formula was the largest and the mean absolute error from the Hoffer Q formula was the smallest.

Conclusions

IOL power prediction may be inaccurate in ACG patients. The Haigis formula produced more inaccurate results in ACG patients, and it is more appropriate to use the Hoffer Q formula to predict IOL powers in eyes with primary ACG.