Accuracy of the Holladay 2 intraocular lens formula for pediatric eyes in the absence of preoperative refraction

A Bayesian network meta-analysis on comparisons of intraocular lens power calculation methods for paediatric cataract eyes

The study aimed to compare and rank the accuracy of formulas for calculating intraocular lens (IOL) power in paediatric eyes in a systematic way. A literature search was conducted in Pubmed, Web of Science, Cochrane Library, and EMBASE by December 2021. Combined with traditional and network meta-analysis, we analysed the percentages of paediatric eyes with prediction error (PE) within ±0.50 dioptres (D) and ±1.00 D as the outcome measurements among different formulas. Subgroup analyses stratified by age were also undertaken. Thirteen studies with 1781 eyes comparing 8 calculation formulas were included. For the traditional meta-analysis results, Sanders-Retzlaff-Kraff theoretical (SRK/T) (risk ratios (RR), 1.15; 95% confidence intervals (CI), 1.03-1.30) performed significantly better than the SRKII formula for the percentage of eyes with PE within ±0.50 D. In addition, SRK/T (RR, 1.10; 95% CI, 1.02-1.18) and Holladay 1(RR, 1.15; 95% CI, 1.01-1.30) both performed significantly better than the SRKII formula for the percentage of eyes with PE within ±1.00 D. Considering the ranking based on the surface under the cumulative ranking curve (SUCRA) by Bayesian method, the top four formulas were Barrett Universal II (UII), Haigis, Holladay 1, and SRK/T on the percentage of PE within ±0.50 D, whereas the top four formulas were Barrett UII, Holladay 1, SRK/T, and Hoffer Q formulas on the percentage of PE within ±1.00D. Concerning both outcome measurements of rank probabilities, the top three Barrett UII, SRK/T, and Holladay 1 formulas were considered to provide more accuracy for IOL power calculation in paediatric cataract eyes, and Barrett UII tends to perform better in older children.

The contribution of intraocular lens calculation accuracy to the refractive error predicted at 10 years in the Infant Aphakia Treatment Study

PURPOSE

To determine the relative contribution of intraocular lens (IOL) calculation accuracy and ocular growth variability to the long-term refractive error predicted following pediatric cataract surgery.

METHODS

Pseudophakic eyes of children enrolled in the Infant Aphakia Treatment Study (IATS) were included in this study. Initial absolute prediction error (APE) and 10-year APE were calculated using the initial biometry, IOL parameters, postoperative refractions, and mean rate of refractive growth. The cohort was divided into children with a low-initial APE (≤1.0 D) and a high-initial APE ( >1.0 D). The 10-year APE was compared between the two groups using the Mann-Whitney U test. Linear regression was used to estimate the variability in prediction error explained by the initial IOL calculation accuracy.

RESULTS

Forty-two children with IOL placement in infancy were included. Seventeen eyes had a low initial APE, and 25 eyes had a high initial APE. There was no significant difference in APE 10 years following surgery between individuals with a low initial APE (median, 2.67 D; IQR, 1.61-4.12 D) and a high initial APE (median, 3.45 D; IQR, 1.64-5.10 D) (P = 0.7). Initial prediction error could explain 12% of the variability in the prediction error 10 years following surgery.

CONCLUSIONS

IOL calculation accuracy contributed minimally to the refractive error predicted 10 years after cataract surgery in the setting of high variability in the rate of refractive growth.

Challenges in pediatric cataract surgery: comparison of intraocular lens power calculation formulas using optical biometry

PURPOSE

Comparison of the accuracy of intraocular lens (IOL) power calculation formulas (SRK II, SRK/T, Holladay 1, Hoffer Q and Barrett II Universal, Haigis) in pediatric cataract surgery using optical biometry.

METHOD

This prospective study included seventy eyes of 70 patients between ages of 3-15 who had undergone cataract surgery with IOL implantation. Anterior segment parameters and axial length (AL) were measured with an optical biometer. Barrett II Universal formula results were used to determine the diopter of implanted IOL. Postoperative refraction was taken at first month, and differences from the estimated refractive value [mean absolute predictive error (APE)] were compared between formulas. Formulas were also compared according to AL.

RESULTS

The lowest APE was achieved with Barrett II formula (0.64 ± 0.73D) and the highest with Haigis formula (1.06 ± 0.84D) in the whole study population (p < 0.01). APE values were lowest with Holladay 1 (0.79 ± 0.71D) and highest with Haigis (1.44 ± 0.92D) in patients with an AL ≤ 22 mm; lowest APE was achieved with Barrett II (0.47 ± 0.54D) and highest with Haigis (0.84 ± 0.72D) in patients with an AL > 22 mm.

CONCLUSION

Barrett II formula had the best results in eyes with average AL, and SRK/T and Holladay 1 formulas were better in eyes with shorter AL. Haigis formula statistically had the highest predictive error in all formulas.

Accuracy of Intraocular Lens Power Calculation Formulas in Pediatric Cataract Patients: A Systematic Review and Meta-Analysis

Background: Among the various intraocular lens (IOL) power calculation formulas available in clinical settings, which one can yield more accurate results is still inconclusive. We performed a meta-analysis to compare the accuracy of the IOL power calculation formulas used for pediatric cataract patients.

Methods: Observational cohort studies published through April 2021 were systematically searched in PubMed, Web of Science, and EMBASE databases. For each included study, the mean differences of the mean prediction error and mean absolute prediction error (APE) were analyzed and compared using the random-effects model.

Results: Twelve studies involving 1,647 eyes were enrolled in the meta-analysis, and five formulas were compared: Holladay 1, Holladay 2, Hoffer Q, SRK/T, and SRK II. Holladay 1 exhibited the smallest APE (0.97; 95% confidence interval [CI]: 0.92–1.03). For the patients with an axial length (AL) less than 22 mm, SRK/T showed a significantly smaller APE than SRK II (mean difference [MD]: −0.37; 95% CI: −0.63 to −0.12). For the patients younger than 24 months, SRK/T had a significantly smaller APE than Hoffer Q (MD: −0.28; 95% CI: −0.51 to −0.06). For the patients aged 24–60 months, SRK/T presented a significantly smaller APE than Holladay 2 (MD: −0.60; 95% CI: −0.93 to −0.26).

Conclusion: Due to the rapid growth and high variability of pediatric eyes, the formulas for IOL calculation should be considered according to clinical parameters such as age and AL. The evidence obtained supported the accuracy and reliability of SRK/T under certain conditions.

Systematic Review Registration: PROSPERO, identifier: INPLASY202190077.

Predictive Value of Intraocular Lens Power Calculation Formulae in Children

Purpose

To compare the accuracy of IOL power calculation formulae in a large cohort of children who underwent IOL implantation.

Setting

Cairo University Children Hospital.

Design

Retrospective, case series.

Methods

A retrospective chart review of all children <14 years, who underwent primary or secondary IOL implantation in Cairo University Children Hospital from January 2016 to December 2019, was performed. Absolute prediction error (APE) was calculated for SRKII, SRK/T, Holladay I and Hoffer-Q formulae using the patients' AL, keratometric (K) readings, implanted IOL power and refraction done two months postoperatively.

Results

The study included 308 eyes of 255 patients with a mean age of 4.74 ± 3.19 years at the time of surgery. The mean K-reading was 43.42 ± 3.57 diopters (D) and mean AL was 22.01 ± 1.93 mm. The percentage of eyes with APE within 0.5D was 27.7% (85 eyes), 32.2% (99 eyes), 30.6% (94 eyes) and 25.4% (78 eyes) with SRK II, SRK/T, Holladay I and Hoffer-Q formulae, respectively. APE was significantly lower with the SRK/T formula (P≤0.004) and significantly higher with the Hoffer-Q formula (P≤ 0.002). There was a negative correlation between the age of the patient and the APE of the SRK II formula (P=0.02). Moreover, the SRK/T, Holladay and Hoffer-Q formulae APEs were affected by the average k-readings (P=0.019, 0.005 and 0.035) respectively.

Conclusion

The SRK/T and Holladay I formulae were the most predictable formulae in IOL power calculation in pediatric eyes.

Evaluation and comparison of a novel Scheimpflug-based optical biometer with standard partial coherence interferometry for biometry and intraocular lens power calculation

In the present study, the axial length (AL), corneal curvature, anterior chamber depth (ACD) and white-to-white (WTW) distance were assessed using the Pentacam AXL (Oculus Optikgeraete GmbH), a novel Scheimpflug-based optical biometer with standard partial coherence interferometry (PCI). The Pentacam AXL and PCI biometer (IOLMaster 500; Carl Zeiss AG) were compared in terms of their intraocular lens (IOL) power calculations. The medical records of patients (eyes, n=190) who underwent cataract surgery were retrospectively reviewed. Biometry measurements involved the eyes of patients with cataract and were performed by the same examiner with the Pentacam AXL biometer and the IOLMaster 500 device. Following determination of the AL, mean keratometry (Km), ACD and WTW distance, the IOL power calculation was compared between the two devices using the Sanders, Retzlaff and Kraff theoretical (SRK/T) and Haigis formulas. The AL, Km and WTW values for the Pentacam AXL group were significantly lower compared with those of the IOLMaster 500 group. The difference was -0.02±0.04 mm, -0.20±0.28 D and -0.10±0.20 mm, respectively (P<0.001). The ACD for the Pentacam AXL group was higher compared with that of the IOLMaster 500 group with a difference of 0.02±0.13 mm (P=0.13). The IOL power calculated using the SRK/T and Haigis formulas exhibited significant differences between the two devices (t=11.48 and 10.97, respectively; P<0.001). In conclusion, the AL, ACD, WTW measurement and IOL power indicated optimal agreement and strong correlations between the two devices. However, constant optimization may be necessary for the novel biometer Pentacam AXL.

Accuracy of intraocular lens power calculations in paediatric eyes

IMPORTANCE

There is no clear consensus on which intraocular lens (IOL) power calculation formula provides the best refractive prediction in the paediatric population.

BACKGROUND

To evaluate the predictability of desired postoperative refractive outcomes by using six IOL formulas in paediatric cataract cases.

DESIGN

Retrospective case series.

PARTICIPANTS

A total of 377 eyes in 377 paediatric patients (<13 years of age) who received primary IOL implants in the capsular bag.

METHODS

This study utilized formulas, namely, SRK II, SRK/T, Hoffer Q, Holladay 1, T2 and Super formula. Prediction errors were calculated based on the difference between the postoperative refraction and the refraction predicted by each formula.

MAIN OUTCOME MEASURES

The mean prediction error, mean absolute error, median absolute error, percentages of eyes within the prediction errors of ±0.50 D, ±1.00 D and ± 2.00 D.

RESULTS

The mean axial length was 22.48 ± 1.91 mm (<22.0 mm for 161 eyes). The average age at surgery was 55.21 ± 28.01 months (<24 months for 37 eyes). The mean prediction error was positive (hyperopic error) with all formulas. Compared to the other IOL power formulas, SRK II showed significantly higher absolute errors (P < .001). Hoffer Q and Holladay 1 generated the least absolute error, followed closely by Super formula. Multiple logistic analyses indicated that age at time of surgery was an independent factor significantly contributing to the refractive surprise using all formulas.

CONCLUSIONS AND RELEVANCE

SRK II was the least predictable formula in this study. HofferQ and Holladay 1 yielded the best predictive values.

Retrospective comparative analysis of intraocular lens calculation formulas after hyperopic refractive surgery

Purpose

To compare the intraocular lens calculation formulas and evaluate postoperative refractive results of patients with previous hyperopic corneal refractive surgery.

Design

Retrospective, comparative, observational study.

Setting

Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts, USA.

Methods

Clinical charts and optical biometric data of 39 eyes from 24 consecutive patients diagnosed with previous hyperopic laser vision correction and cataract surgery were reviewed and analyzed. The Intraocular lens (IOL) power calculation using the Holladay 2 formula (Lenstar) and the American Society of Cataract and Refractive Surgery (ASCRS) Post-Refractive IOL Calculator (version 4.9, 2017) were compared to the actual manifest refractive spherical equivalent (MRSE) following cataract surgery. No pre-Lasik / PRK or post-Lasik / PRK information was used in any of the calculations. The IOL prediction error, the mean IOL prediction error, the median absolute refractive prediction error, and the percentages of eyes within ±0.50 diopter (D) and ±1.00 D of the predicted refraction were calculated.

Results

The Holladay 2 formula produced a mean arithmetic IOL prediction error significantly different from zero (P = 0.003). Surprisingly, the mean arithmetic IOL prediction errors generated by Shammas, Haigis-L and Barret True K No History formulas were not significantly different from zero (P = 0.14, P = 0.49, P = 0.81, respectively).There were no significant differences in the median absolute refractive prediction error or percentage of eyes within ± 0.50 D or ± 1.00 D of the predicted refraction between formulas or methods.

Conclusion

In eyes with previous hyperopic LASIK/PRK and no prior data, there were no significant differences in the accuracy of IOL power calculation between the Holladay 2 formula and the ASCRS Post-refractive IOL calculator.

Accuracy of new and standard intraocular lens power calculations formulae in Saudi pediatric patients

PURPOSE

The purpose of this study is to compare the accuracy of new generation formulas to standard formulas for intraocular lens (IOL) power calculations in pediatric patients.

SUBJECTS AND METHODS

This retrospective case series compared the postoperative refractions to the predicted refractions after lensectomy and IOL implantation in pediatric patients. Four new generation formulas (Haigis, Holladay II, Olsen, and Barrett Universal II) were compared to four standard formulas (Holladay I, Hoffer Q, SRK/T, and SRKII) 4. The absolute prediction error (APE) was calculated as the absolute difference between the actual postoperative spherical equivalent and predicted spherical equivalent). The Friedman test was used to evaluate the difference between formulas. P < 0.05 was statistically significant.

RESULTS

The study sample was comprised 44 eyes from 29 patients (20 males and 9 females) with median age at surgery of 2.85 years (2.04-6.14 years). The Holladay I and II, Barrett Universal II, SRK/T, SRKII, Olsen, and Hoffer Q formulas had comparable median APE (MedAPE) of 1.32 D (0.51-2.11 D), 1.34 D (0.82-1.94 D), 1.28 D (0.73-1.85 D), 1.26 D (0.60-2.08 D), 1.16 D (0.54-1.16 D), 1.34 D (0.80-1.98 D), and 1.27 D (0.63-2.08 D), respectively (P = 1.0). The Haigis formula had the statistically highest MedAPE of 2.00 D (1.27-3.04 D) (P < 0.001). More than 70% of eyes were within ±2.0 D for the Holladay I and II, Barrett Universal II, SRK/T, SRKII, Olsen, and Hoffer Q formulas. Fifty percent of eyes were within ±2.0 D for the Haigis formula.

CONCLUSION

New generation IOL formulas do not outperform standard IOL formulas in predicting postoperative refraction for pediatric patients.

Three-dimensional non-parametric method for limbus detection

Purpose

To present a novel non-parametric algorithm for detecting the position of the human eye limbus in three dimensions and a new dynamic method for measuring the full 360° visible iris boundary known as white-to-white distance along the eye horizontal line.

Methods

The study included 88 participants aged 23 to 65 years (37.7±9.7), 47 females and 41 males. Clinical characteristics, height data and the apex coordinates and 1024×1280 pixel digital images of the eyes were taken by an Eye Surface Profiler and processed by custom-built MATLAB codes. A dynamic light intensity frequency based white-to-white detection process and a novel three-dimensional method for limbus detection is presented.

Results

Evidence of significant differences (p<0.001) between nasal-temporal and superior-inferior white-to-white distances in both right and left eyes were found (nasal-temporal direction; 11.74±0.42 mm in right eyes and 11.82±0.47 mm in left eyes & superior-inferior direction; 11.52±0.45 mm in right eyes and 11.55±0.46 mm in left eyes). Average limbus nasal-temporal diameters were 13.64±0.55 mm for right eyes, and 13.74±0.40 mm for left eyes, however the superior-inferior diameters were 13.65±0.54 mm, 13.75±0.38 mm for right and left eyes, respectively. No significant difference in limbus contours has been observed either between the nasal-temporal direction (p = 0.91) and the superior-inferior direction (p = 0.83) or between the right (p = 0.18) and left eyes (p = 0.16). Evidence of tilt towards the nasal-temporal side in the three-dimensional shape of the limbus was found. The right eyes mean limbus contour tilt around the X-axis was -0.3±1.35° however, their mean limbus contour tilt around the Y-axis was 1.76±0.9°. Likewise, the left eyes mean limbus contour tilt around the X-axis was 0.77±1.25° and the mean limbus contour tilt around the Y-axis was -1.54±0.89°.

Conclusions

The white-to-white distance in the human eye is significantly larger in the nasal-temporal direction than in the superior-inferior direction. The human limbus diameter was found not to vary significantly in these directions. The 3D measures show that the limbus contour does not lay in one plane and tends to be higher on the nasal-inferior side of the eye.

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

PURPOSE

To develop and compare the accuracy and reproducibility of the VRF intraocular lens (IOL) power calculation formula with well-known methods.

DESIGN

Development and validation study.

METHODS

This analysis comprised 823 eyes of 823 patients at Kiev Clinical Ophthalmology Hospital Eye Microsurgery Center, Kiev, Ukraine, operated on by 1 surgeon with 3 different types of hydrophobic lenses: IQ SN60WF (494 eyes) and ReSTOR SN6AD1 (169 eyes) (Alcon Labs, Fort Worth, Texas, USA) and AMO Tecnis MF ZMB00 (160 eyes) (J&J Vision, Santa Ana, California, USA). The full data set was divided into 2 subsets, the first to develop the new formula and the second to evaluate their performance with other most commonly used modern methods of IOL power calculation (Haigis, Hoffer Q, Holladay 1, Holladay 2, SRK/T, and T2). The VRF algorithm is empirical; it uses 4 predictors for estimation of postoperative lens position, including axial length, corneal power (K), preoperative anterior chamber depth (corneal epithelium to lens), and horizontal corneal diameter. The results are also stratified into groups of short (≤22 mm), medium (>22 to <24.5 mm), medium-long (≥24.5 to <26 mm), and long (≥26 mm) axial length.

RESULTS

The mean error, median absolute error, and mean absolute error were evaluated for all 7 methods with 1 IOL type. The VRF formula had the lowest median (0.305 diopter [D]) absolute error over the entire axial length range, and was comparable with the formulas for T2 (0.321 D) and Holladay 1 (0.326 D).

CONCLUSION

The new formula was comparable with well-known methods and was better over the entire axial length range.

Current Status of IOL implantation in pediatric eyes: an update

INTRODUCTION

Pediatric cataracts are a huge problem worldwide, and with improving techniques and technology, the surgical treatment and postoperative visual rehabilitation are improving. Despite intraocular lenses(IOLs) being the standard of care for adult cataract surgery, this issue is still somewhat controversial, particularly in young children and infants due to lack of unequivocal evidence. This review therefore summarises the findings from recent studies on the aspect of IOL implantation in pediatric eyes. Areas covered: An extensive literature search was undertaken for published articles on congenital/developmental pediatric cataracts, and IOL implantation, where literature pertinent to traumatic and subluxated cataracts was not included in the review. Pubmed was used for literature search, and keywords entered were : pediatric, cataract surgery, intraocular lens, persistent fetal vasculature, outcomes, complications, visual performance with intraocular lenses. Expert commentary: Recent literature supports IOL implantation in most cases of congenital / developmental pediatric cataracts, and it seems like the way forward. However, the jury is still out on IOL implantation in infants, particularly in bilateral cataracts. Thus, surgeons must be extremely cautious in planning primary IOL implantation in infant eyes, and if they do perform IOL implantation, rigorous followup is mandatory.

Comparison of IOL power calculation formulae for pediatric eyes

PurposeTo evaluate and compare the accuracy of modern intraocular lens (IOL) power calculation formulae in pediatric eyes and compare prediction error (PE) obtained with manufacturer's vs personalized lens constant.Patients and methodsAn observational case study was conducted in 117 eyes (117 patients) undergoing pediatric cataract surgery with IOL implantation. PE was calculated as predicted refraction minus actual postoperative refraction, and absolute PE as absolute difference independent of the sign, (APE)=predicted refraction minus actual postoperative refraction. This was done for each formula using manufacturer's and personalized lens constant. Further, PE and APE were evaluated according to axial length (AL).ResultsMean age of children was 2.97 years. About 66/117 eyes (56.4%) were below 2 years of age. Using Holladay 2, Holladay 1, Hoffer Q, and SRK/T formulae with manufacturer's lens constant, mean PE was 0.36, 0.41, 0.69, and 0.28 diopter (D), respectively. With personalized lens constant, it was 0.16, 0.15, 0.50, and -0.12 D, respectively. Difference in mean PE between the formulae was statistically significant (P<0.0001). SRK/T and Holladay 2 formulae had the least PE, both with manufacturer's and personalized constant. For eyes with AL<20 mm, SRK/T and Holladay 2 formulae gave the least PE. Personalizing the lens constant led to a decrease in mean PE in all formulae, except the Hoffer Q formula. However, personalizing the lens constant did not significantly improve the APE. At least 21% eyes had an APE of >2 D with all formulae, even with personalized lens constants.ConclusionIn pediatric eyes, SRK/T and the Holladay 2 formulae had the least PE. Personalizing the lens formula constant did reduce the PE significantly for all formulae except Hoffer Q. In extremely short eyes (AL<20 mm), SRK/T and Holladay 2 formulae gave the best PE.

Measurement of Axial Length in an Office Setting Versus Under General Anesthesia in Infants and Toddlers: A Comparative Study

PURPOSE

To examine whether axial length measurement in awake infants and toddlers is feasible, and whether there is a difference in axial length measurement between an office setting and under general anesthesia.

METHODS

This prospective comparative case study was conducted at the Goldschleger Eye Institute, Sheba Medical Center, Israel. Using the same instruments, axial length measurements were obtained using a standard applanation technique twice: once in an office setting when the infant/toddler was awake and once under general anesthesia in the operating room. A paired t test was used to test for differences between measurements.

RESULTS

Thirty-three eyes of 19 participants younger than 28 months were examined; 24 (73%) eyes had cataracts and the remainder had clear lenses. One child was excluded from the study due to lack of cooperation during axial length measurement in the office setting and another due to the lengthy gap between measurements. Of the remaining 31 children, the average age was 9 months. Average axial length measurements were shorter by 0.12 mm in the office setting than under general anesthesia (P = .14). No adverse effects were observed after axial length measurements in the office setting.

CONCLUSIONS

Axial length measurement in an office setting is generally reasonable to obtain. The results showed no significant difference in the axial length measured in the two settings.

Multi-component adjustable intraocular lenses: a new concept in pediatric cataract surgery

PURPOSE

The multi-component intraocular lens (IOL) (IVO; SAS, Strasbourg, France) is a novel approach to the treatment of pediatric cataract. Because the refractive requirements for pediatric eyes often change over time, current IOL technology does not easily allow refractive adjustments after the primary surgical intervention. The multi-component IOL concept allows easy, surgical refractive adjustments to the initial surgical implantation at any postoperative time period. Thus, both surgical implantation and enhancement surgery have been successfully accomplished in adult patients.

METHODS

A novel surgical approach to pediatric cataract surgery is described. At the time of the primary surgery, a two component IOL was implanted. At any postoperative time period, the front lens component, located in front of the capsular bag, could be easily surgically exchanged because the dioptric power requirements of the pediatric eye changed over time.

RESULTS

Both primary and enhancement surgeries have been done in adult patients with good results. Implantations have occurred uneventfully in all cases with no intraoperative or postoperative complications. There was no statistically significant difference in the endothelial cell density, anterior chamber depth, and pachymetry readings preoperatively and 2 years postoperatively. There was no interlenticular fibrosis present.

CONCLUSION

The multi-component IOL should provide a unique and greatly needed surgically adjustable approach to the treatment of pediatric cataract.

Accuracy of Holladay 2 formula using IOLMaster parameters in the absence of lens thickness value

BACKGROUND

The accuracy of the Holladay 2 (H2) formula is well-documented. This formula requires seven variables to estimate effective lens position (ELP) for the IOL power calculation. The lens thickness (LT) value is one of the required variables. Interestingly, the IOLMaster, which is one of the most commonly used optical biometers, can provide all the required ocular variables except LT value. It has become a pertinent issue to evaluate the accuracy of theH2 formula when it is used without the LT value. The purpose of this study was to evaluate the results when using the H2 formula, without the LT value, and compare such results to those obtained using the Haigis formula and the Hoffer Q formula.

METHODS

The Institutional review board (IRB) gave their approval for the conduct of this prospective comparative study. One hundred and sixty-three eyes of 143 cataract patients from the Ophthalmology Department, Siriraj Hospital, Thailand were recruited. All eyes were measured using the IOLMaster (Carl Zeiss Meditec, Jena, Germany) for keratometry (K), axial length (AL), anterior chamber depth (ACD), and horizontal white-to-white (WTW) corneal diameter. Then, the LT measurement was obtained by A-scan ultrasonography (Quantel Axis-II, Quantel Medical, USA). Every patient underwent uncomplicated phacoemulsification by a single surgeon (NC) with a single technique using a single IOL model. Post-operative refraction was obtained at 3 months. The mean absolute errors (MAEs), median absolute errors (MedAEs) and percentage of the eyes within ±0.25, ±0.50, and ±1.00 D of predicted refraction was calculated for H2 formula both with and without LT input, Haigis, and Hoffer Q formula. The results were also classified into a group of short AL (<22.0 mm), average AL (22.0 to 24.5 mm) and long AL (>24.5 mm).

RESULTS

There was no statistically significant difference in either MAEs or MedAEs of all formulas in all AL groups including the H2 with and without LT. There was a trend toward lower MAEs and MedAEs for H2 in the long AL group. Percentage of the eyes within ±0.25, ±0.50, and ±1.00 D of predicted refraction were similar in all AL groups.

CONCLUSION

The preliminary results of this study showed that the H2 formula performed well even without the LT value. It was comparable to the Haigis and Hoffer Q formulas.

Visual outcome of cataract in pediatric age group: does etiology have a role

PURPOSE

To compare visual outcome results among traumatic and nontraumatic groups of eyes with cataract in the pediatric age group.

METHOD

This is a retrospective cohort study. This study comprised a consecutive series of pediatric patients under 5 years of age with unilateral congenital, developing, or traumatic cataract who underwent surgery between January 1999 and April 2012 at Drashti Netralaya, Dahod. Records were retrieved from the medical record department. Patients were grouped as traumatic or nontraumatic and their demographics, cataract type, presenting symptoms, surgical intervention, and postoperative visual acuity follow-up refractive changes were recorded and compared.

RESULTS

A total of 128 eyes of 128 children under 5 years of age were included with unilateral cataract. A total of 85 (66.4%) were traumatic and 43 (33.3%) nontraumatic. The age at surgery ranged from 1 to 60 months. Eyes were grouped by etiology: group 1- traumatic 85 (66.4%) eyes that had traumatic cataracts. Group 2 non-traumatic 43 (33.3%) eyes that had congenital, developmental or complicated cataracts. The mean follow-up time was 117 days. Finally, 22 (51.1%) group 1 patients and 40 (47.1%) group 2 patients achieved visual acuity better than 20/200 (p = 0.000).

CONCLUSIONS

Surgical treatment with intraocular lens implantation for children with congenital, developmental, or traumatic cataract is an effective treatment for visual rehabilitation. Visual outcome is significantly better (p = 0.005) in case of nontraumatic cataracts than traumatic cataracts.

Pediatric intraocular lens power calculations

PURPOSE OF REVIEW

To implant an appropriate intraocular lens (IOL) in a child, we must measure the eye well, calculate the IOL power accurately and predict the refractive change of the pseudophakic eye to maturity. The present review will concentrate on recent studies dealing with these issues.

RECENT FINDINGS

Immersion A-scan biometry is superior in measuring the axial length of children. Current IOL power calculation formulas are very accurate in adults, but significantly less accurate in children. Several studies point to the high prediction errors encountered particularly in shorter eyes with all available IOL formulas. Postoperative refraction target remains controversial, but low degrees of overcorrection (i.e. hyperopia) may not adversely affect eventual best-corrected visual acuity.

SUMMARY

Although pediatric IOL power calculations suffer from significant prediction error, these errors can be decreased by careful preoperative measurements. IOL power calculation formulas are most accurate in the older, more 'adult'-sized eye. The smallest eyes have the most prediction error with all available formulas. Individual circumstances and parental concerns must be factored into the choice of a postoperative refractive target.

Reanalysis of refractive growth in pediatric pseudophakia and aphakia

BACKGROUND

The current model of refractive growth in children (RRG2) is calculated as the slope of aphakic refraction at the spectacle plane versus the logarithm of adjusted age. However, this model fails in infants because of the optical effect of vertex distance of a spectacle lens on the effective power at the cornea. In this study, we developed a new model of refractive growth (RRG3) that eliminates the optical effect of vertex distance on the RRG2 model.

METHODS

We calculated RRG3 values for pseudophakic and aphakic eyes previously analyzed for RRG2. Inclusion criteria were age ≤10 years at the time of cataract surgery and follow-up time between measured refractions of at least 3.6 years and at least the age at first refraction plus 0.6 years. For both pseudophakic and aphakic eyes, we compared RRG3 values in children who had cataract surgery before age 6 months with those in children aged 6 months or older.

RESULTS

A total of 78 pseudophakic and 70 aphakic eyes met the inclusion criteria. Ages at surgery ranged from 0.25 to 9 years, with a 9.5-year mean follow-up time. The mean RRG3 value was not significantly different between the surgical age groups for both pseudophakic eyes (P = 0.053) and aphakic eyes (P = 0.59).

CONCLUSIONS

The RRG3 values were not significantly different between the surgical age groups for both pseudophakic and aphakic eyes. Consequently, RRG3 is theoretically applicable even in the small eyes of infants having surgery before 6 months of age.

Update of intraocular lens implantation in children

Cataract is a common problem that affects the vision in children and a major cause of amblyopia in children. However, the management of childhood cataract is tenuous and requires special considerations especially with regard to intraocular lens (IOL) implantation. Age at which an IOL can be implanted is a controversial issue. Implanting an IOL in very young children carries the risk of severe postoperative inflammation and posterior capsule opacification that may need other surgeries and may affect the vision permanently. Accuracy of the calculated IOL power is affected by the short eyes and the steep keratometric values at this age. Furthermore, choosing an appropriate IOL power is not a straight forward decision as future growth of the eye affects the axial length and keratometry readings which may result in an unexpected refractive error as children age. The aim of this review is to cover these issues regarding IOL implantation in children; indications, timing of implantation, types of IOLs, site of implantation and the power calculations.