Accuracy of biometry in pediatric cataract extraction with primary intraocular lens implantation

Intraocular Lens Power Calculation Formulas in Children-A Systematic Review

Objectives: The selection of an appropriate formula for intraocular lens power calculation is crucial in phacoemulsification, particularly in pediatric patients. The most commonly used formulas are described and their accuracy evaluated in this study. Methods: This review includes papers evaluating the accuracy of intraocular lens power calculation formulas for children's eyes published from 2019-2024. The articles were identified by a literature search of medical and other databases (Pubmed/MEDLINE, Crossref, Google Scholar) using the combination of the following key words: "IOL power calculation formula", "pediatric cataract", "congenital cataract", "pediatric intraocular lens implantation", "lens power estimation", "IOL power selection", "phacoemulsification", "Hoffer Q", "Holladay 1", "SRK/T", "Barrett Universal II", "Hill-RBF", and "Kane". A total of 14 of the most recent peer-reviewed papers in English with the maximum sample sizes and the greatest number of compared formulas were considered. Results: The outcomes of mean absolute error and percentage of predictions within ±0.5 D and ±1.0 D were used to assess the accuracy of the formulas. In terms of MAE, Hoffer Q yielded the best result most often, just ahead of SRK/T and Barrett Universal II, which, together with Holladay 1, most often yielded the second-best outcomes. Considering patients with PE within ±1.0 D, Barrett Universal II most often gave the best results and Holladay 1 most often gave the second-best. Conclusions: Barrett Universal II seems to be the most accurate formula for intraocular lens calculation for children's eyes. Very good postoperative outcomes can also be achieved using the Holladay 1 formula. However, there is still no agreement in terms of formula choice.

Accuracy of the SRK/T Formula in Pediatric Cataract Surgery

PURPOSE

Determining IOL power is an important step in achieving the desired postoperative refractive target, but this determination remains challenging, as currently the used formulas were developed using IOL power calculations derived from adults.

PATIENTS AND METHODS

This is a retrospective analytical study with the period of June 2018 to May 2019. All of the data were taken from medical records in referral tertiary eye hospital in Indonesia. All type of cataracts underwent uncomplicated surgeries and in-the-bag IOL implantation were included in this study, while aphakia, secondary IOL implantation, primary sulcus implantation, and history of ocular disorders were excluded. The data were analyzed using Wilcoxon sign-rank, paired t, and Kruskal-Wallis tests.

RESULTS

Sixty-seven patients (106 eyes) were found to meet the inclusion criteria, average age was 7.35 ± 4.61 years (1.00 to 17.00 years). Average targeted refraction was 1.69 ± 2.06 D (-0.38-+6.99 D), and spherical equivalent (actual postoperative refraction) was -0.90 ± 1.45 D (-4.38 to +2.75 D). There was statistically significant difference between preoperative targeted refraction and actual postoperative refraction (p < 0.001). Mean absolute prediction error (APE) in general was 1.34 ± 1.18 D, 1.22 ± 0.88 D (in short eyes), 1.52 ± 1.37 D (in moderate eyes), and 0.69 ± 0.52 D (in long eyes) (p = 0.202). Mean APE in age group <7 years old was 1.27 ± 1.18 D and ≥7 years-old was 1.42 ± 1.19 D (p = 0.429).

CONCLUSION

SRK/T formula is fairly accurate in calculating IOL power in pediatric cataract surgery. Mean APE in this study was within the range of accurate mean APE in pediatric patients despite differentiated axial length and age.

Accuracy of Intraocular Lens Power Calculation Formulas in Patients With Multifocal Intraocular Lens Implantation With Optic Capture in Berger Space for Pediatric Cataract

PURPOSE

To assess the accuracy of intraocular lens (IOL) calculation formulas in pediatric patients with multifocal IOL implantation with optic capture in Berger space.

METHODS

This prospective observational study enrolled 68 children (101 eyes), aged 3 to 14 years, who received multifocal IOL (Tecnis ZMB00; Abbott Medical Optics) implantation with optic capture in Berger space from June 2019 to June 2020 in Qingdao Eye Hospital. Ocular biometry was performed using the IOLMaster 700 (Carl Zeiss Meditec). The IOL power and intended postoperative refraction were calculated using the Hoffer Q, Barrett Universal II, Holladay, Holladay2, SRK/T, Haigis, and SRKII formulas. The refractive state of patients, prediction error, and absolute prediction error were evaluated.

RESULTS

The mean absolute error of the formulas was significantly different (0.49 diopters [D], Hoffer Q; 0.52 D, Barrett Universal II; 0.47 D, Holladay; 0.54 D, Holladay2; 0.52 D, SRK/T; 0.67 D, Haigis; 0.99 D, SRKII; P < .001). However, the Hoffer Q, Barrett Universal II, Holladay, Holladay2, and SRK/T formulas had a similar accuracy in predicting refractive error within ±0.50 D (62.4%, 59.4%, 62.4%, 62.4%, and 58.4%). There was a trend toward a greater prediction error in eyes with a shorter axial length (≤ 22 mm) or a steeper cornea (> 43.50 D), for which the Hoffer Q and Holladay2 formulas were more accurate. When the axial length was greater than 22 mm or the corneal curvature was 43.50 D or less, the Holladay, Hoffer Q, and Barrett Universal II formulas were more accurate.

CONCLUSIONS

For patients with pediatric cataract treated with multifocal IOL implantation with optic capture in Berger space, the Hoffer Q, Barrett Universal II, Holladay, Holladay2, and SRK/T formulas performed better than the other formulas. [J Pediatr Ophthalmol Strabismus. 20XX;X(X):XX-XX.].

Intraocular lens power calculation formula in congenital cataracts: Are we using the correct formula for pediatric eyes?

The major challenge these days in pediatric cataract surgery is not the technique of surgery or intraocular lens (IOL) used but the postoperative refractive error. Amblyopia occurring due to postoperative refractive error which the child has; destroys the benefit obtained by a near-perfect and timely surgery. Even if we settle the debate as to what should be the ideal postoperative target refraction, there is a postoperative surprise that is not explained by our conventional insights of an accurate power calculation in children. The role of IOL power calculation formulae in affecting the postoperative refractive error should not be underestimated. Therefore, which age-appropriate formula is to be used for children is unclear. This review is an update on major IOL power calculation formulas used in pediatric eyes. We have tried to define why we should not be using these formulas made for adult eyes and review the literature in this regard.

Long-term outcome of primary intraocular lens implantation in bilateral congenital cataract in infants with a median age of 35 days at surgery: a case series

Objective

To evaluate the long-term visual outcome and safety after bilateral cataract surgery with primary intraocular lens (IOL) implantation in infants with visually significant cataract at birth operated before 12 weeks of age.

Methods and analysis

Medical records of infants with congenital cataract who had bilateral surgery with primary IOL implantation before 12 weeks of age at Oslo University Hospital between 2007 and 2016 were retrospectively reviewed. Fifteen infants (30 eyes) were enrolled for a prospective study examination in 2017. Corrected distance visual acuity (CDVA) and intraocular pressure (IOP) were assessed. Visual axis opacification (VAO) was defined as opacification on the anterior or posterior surface of the IOL, capsular phimosis or fibrinous membrane. Secondary glaucoma was evaluated according to international guidelines.

Results

Median age at the time of primary surgery was 35 days (range, 15 to 70 days). There were no serious intraoperative complications, and all eyes had the IOL implanted in the capsular bag. After a median follow-up of 6.1 years (range, 1.5 to 10.2 years), the CDVA was 0.5 logMAR (range, 1.2 to 0.04). All eyes had surgery for VAO and the median number of surgical procedures was 2.0 (range, 1 to 5). The cumulative incidence of secondary glaucoma was 10% after 5 years of follow-up.

Conclusion

Primary IOL implantation before 12 weeks of age gave a satisfactory visual outcome, and the incidence of secondary glaucoma was similar to that reported after primary IOL implantation in older infants. However, the risk of VAO was high.

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.

Accuracy of a universal theoretical formula for power calculation in pediatric intraocular lens implantation

PURPOSE

To compare the accuracy of Barrett Universal II formula with other formulas (Holladay 2, Hoffer Q, and SRK/T formulas) in the prediction of postoperative refraction for pediatric intraocular lens implantation.

SETTING

Academic medical center/children's hospital, San Francisco, California.

DESIGN

Retrospective case series.

METHODS

Children aged 16 years or younger who underwent cataract extraction and IOL implantation (2012 to 2019) and had refraction assessed at 3 to 16 weeks postoperatively were included. Prediction error (PE) was calculated as postoperative mean spherical equivalent minus the target refraction. Mean, median, and standard deviation was calculated for PE and absolute PE. Performance across covariables (axial length, age, biometry type, keratometry, etc.) was studied, and a multivariate regression analysis was performed using a single prediction model for each formula.

RESULTS

Sixty-four eyes of 64 patients, aged 1.5 to 15.5 years, were included. Barrett Universal II formula had the lowest mean PE (-0.22 diopters [D]), SD (1.18 D), median PE (-0.26 D), and median absolute PE (0.71) compared with those of the other formulas. Holladay 2 formula performed similarly to Barrett Universal II formula, and SRK/T formula had the greatest mean PE (-0.50 D) and SD (1.22 D). Barrett Universal II formula predictions were stable across all variables.

CONCLUSIONS

Barrett Universal II formula demonstrated similar or superior performance when compared with other formulas in this pediatric study. Holladay 2 formula performed similarly to Barrett Universal II formula, and SRK/T formula had the least reliable performance, across several key biometric characteristics. Although PEs can be highly variable in pediatric populations, this study supports Barrett Universal II formula as a reasonable and reliable option for lens power calculation in children, including those with extreme biometric measurements.

Comparison of the Accuracy of IOL Power Calculation Formulas for Pediatric Eyes in Children of Different Ages

Purpose

This study aims to compare the accuracy of five intraocular lens (IOL) power calculation formulas (SRK/T, Hoffer Q, Holladay 1, Haigis, and Holladay 2) for pediatric eyes in children of different ages.

Methods

In this prospective study, patients who received cataract surgery and IOL implantation in the capsular bag were enrolled. We compared the calculation accuracy of 5 formulas at 1 month postoperatively and performed subgroup analysis with the patients divided into three groups according to their ages at the time of surgery as follows: group 1 (age ≤ 2 years, 35 eyes), group 2 (2 years < age < 5 years, 38 eyes), and group 3 (age > 5 years, 29 eyes).

Results

75 patients (102 eyes) were enrolled in this study. The Haigis formula got the smallest PE among all formulas in all three groups. With regard to APE, there were no statistical differences among the formulas except group 2, with the SRK/T formula a little smaller, the Holladay 2 formula a little larger in group 1, and the Haigis formula a little smaller in group 3. In group 2, the Haigis formula had the lowest APE (0.87 ± 0.61 D), while the Holladay 2 formula had the largest (1.71 ± 1.20 D, p < 0.001), followed by the Holladay 1 formula (1.51 ± 1.07 D, p=0.002). On comparing the percentage of APE within 0.5 D and 1.0 D obtained with 5 formulas in each group, there were no statistical differences. The SRK/T formula and the Holladay 1 formula showed the highest percentage (40.00% and 60.00%) in group 1. While the Haigis formula got the highest percentage in less than 0.5 D (34.21%) and less than 1 D (60.53%) in group 2. In group 3, the Holladay 2 formula and the Haigis formula got the highest percentage less than 0.5 D (58.62%) and less than 1 D (79.31%). The multiple linear regression indicated that the age at the time of surgery was a significant factor affecting the accuracy of APE; after removing the age, AL was the only factor that affected the accuracy of APE.

Conclusion

The SRK/T and the Holladay 1 formulas were relatively accurate in patients younger than 2 years old, while the Haigis formula performed better in patients older than 2.

Accuracy of 8 intraocular lens power calculation formulas in pediatric cataract patients

PURPOSE

To compare the accuracy of the eight formulas for intraocular lens (IOL) power calculation in pediatric cataract patients.

METHODS

A retrospective study. A total of 68 eyes (68 patients) that underwent uneventful cataract surgery and posterior chamber IOL implantation in the capsular bag were enrolled. We compared the calculation accuracy of the 8 formulas at 1 month postoperatively and performed subgroup analysis according to age or axial length (AL).

RESULTS

The mean age at surgery was 34.07 ± 24.60 months and mean AL was 21.12 ± 1.42 mm. The mean prediction errors (PE) of eight formulas for all patients were as follows: SRK II (- 0.66), SRK/T (- 0.44), Holladay 1 (- 0.36), Hoffer Q (- 0.09), Olsen (0.71), Barrett (0.37), Holladay 2 (- 0.70), and Haigis (0.50). There was significant difference among the 8 formulas (p < 0.0001), while no significant difference of absolute PE was found among the 8 formulas in all patients (p = 0.053). Moreover, in patients younger than 2 years old or with AL ≤ 21 mm, SRK/T formula was relatively accurate in 34% and 39% of eyes, respectively. While in patients older than 2 or with AL > 21 mm, Barrett and Haigis formulas were better (58% and 47% for Barrett, 52% and 53% for Haigis).

CONCLUSION

Overall, in patients younger than 2 years old or with AL ≤ 21 mm, SRK/T formulas were relatively accurate, while Barrett and Haigis formulas were better in patients older than 2 or with AL > 21 mm.

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.

Predictability of formulae for intraocular lens power calculation according to the age of implantation in paediatric cataract

Aims

To analyse the predictability of diverse intraocular lens (IOL) power calculation formulae in paediatric patients with congenital cataract.

Methods

The medical records of patients who underwent cataract surgery and posterior chamber IOL implantation (in-the-bag) for congenital cataract before 17 years of age were reviewed retrospectively. Target refractions calculated by Sanders-Retzlaff-Kraff (SRK)/II, SRK/T and Hoffer-Q formulae were compared with the actual refraction. Patients were subgroup according to the age at IOL implantation (age group 0–24 months, 25–60 months, 61–120 months, 121–203 months), and we compared mean prediction error (PE) and mean absolute error (AE) for each formula. Corrected AE was obtained by linear regression analysis.

Results

Totally 481 eyes were included in the final analysis. Both SRK/II and SRK/T yielded the lowest mean AE in the age group 0–24 months and SRK/II yielded the lowest mean AE in the age group 25–60 months. For every formula, the mean PE was positive during the first five years of age, which converged to zero according to age as IOL implantation increases. The tendency for immediate postoperative overcorrection in younger patients (<6 years) could be improved by corrected formulae based on the linear regression equation.

Conclusions

Patients with congenital cataract who underwent IOL implantation within 5 years of age showed higher AE than the older ones did. Among the three formulae evaluated, SRK/II consistently provided the best predictive result in these patients. For patients aged >10 years, all three formulae showed favourable predictive abilities.

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.

Visual Outcomes and Complications of Piggyback Intraocular Lens Implantation Compared to Aphakia for Infantile Cataract

Purpose:

To evaluate the long-term visual outcomes and complications of the piggyback intraocular lens (IOL) implantation compared to aphakia for infantile cataract.

Patients and Methods:

In a comparative study from 1998 to 2007, piggyback IOL implantation (piggyback IOL group) was performed for 14 infants (23 eyes) with infantile cataract and 20 infants (32 eyes) who were aphakic (aphakia group) after infantile cataract surgery. Data were collected on logMAR visual acuity, and postoperative complications over a mean follow-up time of 6.2 ± 1.7 years and 5.8 ± 1.7 years.

Results:

The mean age at surgery was 7.5 ± 0.6 months and 6.0 ± 3.3 months for the piggyback and the aphakic group respectively (P > 0.05). At the last follow-up visit, visual acuity was 0.85 ± 0.73 (median = 0.70, interquartile range = 0.3–1.32) in the piggyback IOL group and 0.89 ± 0.56 (median = 0.86, interquartile range = 0.50–1.24) in the aphakic group (P > 0.05). There was a positive relationship between age and visual outcomes in the aphakic group (r = 0.4, P = 0.04) but not in the piggyback IOL group (P = 0.48). There was no significant difference between the mean myopic shift in the piggyback IOL group (∑5.28 ± 1.06 D) and the aphakic group (∑5.10 ± 1.02 D) (P > 0.05). The incidence of reoperation due to complications in piggyback IOL group was higher than aphakic group (%48 vs. %16, respectively, P ≤ 0.01). However, in patients older than 6 months, this risk was not significantly different compared to the aphakic group.

Conclusions:

Although piggyback IOL implantation for infantile cataract is optically acceptable as a treatment option, there is no significant difference in visual outcomes compared to aphakia. The incidence in reoperation due to complications in patients aged 6 months or younger is higher than those treated with aphakia.

Pediatric cataract: challenges and future directions

Cataract is a significant cause of visual disability in the pediatric population worldwide and can significantly impact the neurobiological development of a child. Early diagnosis and prompt surgical intervention is critical to prevent irreversible amblyopia. Thorough ocular evaluation, including the onset, duration, and morphology of a cataract, is essential to determine the timing for surgical intervention. Detailed assessment of the general health of the child, preferably in conjunction with a pediatrician, is helpful to rule out any associated systemic condition. Although pediatric cataracts have a diverse etiology, with the majority being idiopathic, genetic counseling and molecular testing should be undertaken with the help of a genetic counselor and/or geneticist in cases of hereditary cataracts. Advancement in surgical techniques and methods of optical rehabilitation has substantially improved the functional and anatomic outcomes of pediatric cataract surgeries in recent years. However, the phenomenon of refractive growth and the process of emmetropization have continued to puzzle pediatric ophthalmologists and highlight the need for future prospective studies. Posterior capsule opacification and secondary glaucoma are still the major postoperative complications necessitating long-term surveillance in children undergoing cataract surgery early in life. Successful management of pediatric cataracts depends on individualized care and experienced teamwork. We reviewed the etiology, preoperative evaluation including biometry, choice of intraocular lens, surgical techniques, and recent developments in the field of childhood cataract.

Complications in the first 5 years following cataract surgery in infants with and without intraocular lens implantation in the Infant Aphakia Treatment Study

PURPOSE

To compare rates and severity of complications between infants undergoing cataract surgery with and without intraocular lens (IOL) implantation.

DESIGN

Prospective randomized clinical trial.

METHODS

A total of 114 infants were enrolled in the Infant Aphakia Treatment Study, a randomized, multi-center (12) clinical trial comparing the treatment of unilateral aphakia in patients under 7 months of age with a primary IOL implant or contact lens. The rate, character, and severity of intraoperative complications, adverse events, and additional intraocular surgeries during the first 5 postoperative years in the 2 groups were examined.

RESULTS

There were more patients with intraoperative complications (28% vs 11%, P = .031), adverse events (81% vs 56%, P = .008), and more additional intraocular surgeries (72% vs 16%, P < .0001) in the IOL group than in the contact lens group. However, the number of patients with adverse events in the contact lens group increased (15 to 24) in postoperative years 2-5 compared to the first postoperative year, while it decreased (44 to 14) in years 2-5 compared to the first postoperative year in the IOL group. If only one half of the patients in the contact lens (aphakic) group eventually undergo secondary IOL implantation, the number of additional intraocular surgeries in the 2 groups will be approximately equal.

CONCLUSION

The increased rate of complications, adverse events, and additional intraocular surgeries associated with IOL implantation in infants <7 months of age militates toward leaving babies aphakic if it is considered likely that the family will be successful with contact lens correction.

Predictability of intraocular lens power calculation formulae in infantile eyes with unilateral congenital cataract: results from the Infant Aphakia Treatment Study

PURPOSE

To compare accuracy of intraocular lens (IOL) power calculation formulae in infantile eyes with primary IOL implantation.

DESIGN

Comparative case series.

METHODS

The Hoffer Q, Holladay 1, Holladay 2, Sanders-Retzlaff-Kraff (SRK) II, and Sanders-Retzlaff-Kraff theoretic (SRK/T) formulae were used to calculate predicted postoperative refraction for eyes that received primary IOL implantation in the Infant Aphakia Treatment Study. The protocol targeted postoperative hyperopia of +6.0 or +8.0 diopters (D). Eyes were excluded for invalid biometry, lack of refractive data at the specified postoperative visit, diagnosis of glaucoma or suspected glaucoma, or sulcus IOL placement. Actual refraction 1 month after surgery was converted to spherical equivalent and prediction error (predicted refraction - actual refraction) was calculated. Baseline characteristics were analyzed for effect on prediction error for each formula. The main outcome measure was absolute prediction error.

RESULTS

Forty-three eyes were studied; mean axial length was 18.1 ± 1.1 mm (in 23 eyes, it was <18.0 mm). Average age at surgery was 2.5 ± 1.5 months. Holladay 1 showed the lowest median absolute prediction error (1.2 D); a paired comparison of medians showed clinically similar results using the Holladay 1 and SRK/T formulae (median difference, 0.3 D). Comparison of the mean absolute prediction error showed the lowest values using the SRK/T formula (1.4 ± 1.1 D), followed by the Holladay 1 formula (1.7 ± 1.3 D). Calculations with an optimized constant showed the lowest values and no significant difference between the Holladay 1 and SRK/T formulae (median difference, 0.3 D). Eyes with globe AL of less than 18 mm had the largest mean and median prediction error and absolute prediction error, regardless of the formula used.

CONCLUSIONS

The Holladay 1 and SRK/T formulae gave equally good results and had the best predictive value for infant eyes.

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.

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.

Refractive accuracy after intraocular lens implantation in pediatric cataract

AIM

To analyze the factors that influence the prediction error (PE) after intraocular lens (IOL) implantation in pediatric cataract.

METHODS

The medical records of cataract patients of no more than 14 years old who had primary IOL implantation were reviewed from 2006 to 2010. The PE, absolute value of PE (APE), and predictability between in different axial length, mean corneal curvature, corneal astigmatism, and age at the surgery were analyzed.

RESULTS

Seventy-five children (119 eyes) were included, with a mean age of (5.09±2.54) years. At the follow-up of (1.19±0.69) months, the mean postoperative PE was (-0.22±1.12) D, and APE was (0.87±0.73)D. The PE in eyes with an axial length >20mm but ≤22mm were significantly under-corrected than that in eyes with longer axis, and the APE in eyes with an axial length ≤20mm was more obvious compared with the others. The correlations between PE and axial length, as well as corneal astigmatism, and between APE and axial length were significant. The predictability was significantly poorer in the eyes with an axial length ≤20mm than the others.

CONCLUSION

The axial length is closely related with the PE after IOL implantation in pediatric cataract patients, especially when it is ≤20mm, PE is more significant. The formula that is more suitable to very short axial length should be explored.

Accuracy of intraocular lens power calculation formulae in children less than two years

PURPOSE

To assess the accuracy of IOL power calculation formulae in children less than 2 years of age.

DESIGN

Retrospective, comparative study, comprising of 128 eyes of 84 children.

METHODS

We analyzed records of children less than 2 years with congenital cataract who underwent primary IOL implantation. Data were analyzed for prediction error using the 4 commonly used IOL power calculation formulae. We calculated the absolute prediction error with each of the formulae and the formula that gave least variability was determined. The formula that gave the best prediction error was determined.

RESULTS

Mean age at surgery was 11.7 ± 6.2 months. Absolute prediction error was found to be 2.27 ± 1.69 diopters (D) with SRK II, 3.23 ± 2.24 D with SRK T, 3.62 ± 2.42 D with Holladay, and 4.61 ± 3.12 D with Hoffer Q. The number of eyes with absolute prediction error within 0.5 D was 27 (21.1%) with SRK II, 8 (6.3%) with SRK T, 12 (9.4%) with Holladay, and 5 (3.9%) with Hoffer Q. Comparison between different formulae showed that the absolute prediction error with SRK II formula was significantly better than with other formulae (P < .001). Prediction error with SRK II formula was not affected by any factor such as age (P = .31), keratometry (P = .32), and axial length (P = .27) of the patient. Axial length influenced the absolute prediction error with Holladay (P = .05) and Hoffer Q formulae (P = .002). Mean keratometry influenced prediction error (P = .03) with SRK T formula.

CONCLUSION

Although absolute prediction error tends to remain high with all present IOL power calculation formulae, SRK II was the most predictable formula in our series.

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.

Long-term Outcomes of Undercorrection Versus Full Correction After Unilateral Intraocular Lens Implantation in Children

PURPOSE

To evaluate the impact of full correction vs undercorrection on the magnitude of the myopic shift and postoperative visual acuity after unilateral intraocular lens (IOL) implantation in children.

DESIGN

Retrospective case control study.

METHODS

The medical records of 24 children who underwent unilateral cataract surgery and IOL implantation at 2 to <6 years of age were reviewed. The patients were divided into 2 groups based on their 1-month-postoperative refraction: Group 1 (full correction) -1.0 to +1.0 diopter (D) and Group 2 (undercorrection) ≥+2.0 D. The main outcome measures included the change in refractive error per year and visual acuity for the pseudophakic eyes at last follow-up visit. The groups were compared using the independent groups t test and Wilcoxon rank sum test.

RESULTS

The mean age at surgery (Group 1, 4.2±0.9 years, n=12; Group 2, 4.5±1.0 years, n=12; P=.45) and mean follow-up (Group 1, 5.8±3.7 years; Group 2, 6.1±3.5 years; P=.69) were similar for the 2 groups. The change in refractive error (Group 1, -0.4±0.5 D/y; Group 2, -0.3±0.2 D/y; P=.70) and last median logMAR acuity (Group 1, 0.4; Group 2, 0.4; P=.54) were not significantly different between the 2 groups.

CONCLUSIONS

We did not find a significant difference in the myopic shift or the postoperative visual acuity in children aged 2 to <6 years of age following unilateral cataract surgery and IOL implantation if the initial postoperative refractive error was near emmetropia or undercorrected by 2 diopters or more.

Predictability of intraocular lens calculation and early refractive status: the Infant Aphakia Treatment Study

OBJECTIVE

To report the accuracy of intraocular lens (IOL) power calculations and the early refractive status in pseudophakic eyes of infants in the Infant Aphakia Treatment Study.

METHODS

Eyes randomized to receive primary IOL implantation were targeted for a postoperative refraction of +8.0 diopters (D) for infants 28 to 48 days old at surgery and +6.0 D for those 49 days or older to younger than 7 months at surgery using the Holladay 1 formula. Refraction 1 month after surgery was converted to spherical equivalent, and prediction error (PE; defined as the calculated refraction minus the actual refraction) and absolute PE were calculated. Baseline eye and surgery characteristics and A-scan quality were analyzed to compare their effect on PE.

MAIN OUTCOME MEASURES

Prediction error.

RESULTS

Fifty-six eyes underwent primary IOL implantation; 7 were excluded for lack of postoperative refraction (n = 5) or incorrect technique in refraction (n = 1) or biometry (n = 1). Overall mean (SD) absolute PE was 1.8 (1.3) D and mean (SD) PE was +1.0 (2.0) D. Absolute PE was less than 1 D in 41% of eyes but greater than 2 D in 41% of eyes. Mean IOL power implanted was 29.9 D (range, 11.5-40.0 D); most eyes (88%) implanted with an IOL of 30.0 D or greater had less postoperative hyperopia than planned. Multivariate analysis revealed that only short axial length (<18 mm) was significant for higher PE.

CONCLUSIONS

Short axial length correlates with higher PE after IOL placement in infants. Less hyperopia than anticipated occurs with axial lengths of less than 18 mm or high-power IOLs. Application to Clinical Practice Quality A-scans are essential and higher PE is common, with a tendency for less hyperopia than expected.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00212134.

Axial length measurements by contact and immersion techniques in pediatric eyes with cataract

PURPOSE

To compare axial length measurements by contact and immersion techniques in pediatric cataractous eyes.

DESIGN

Prospective, comparative case series.

PARTICIPANTS

In this prospective study, 50 cataractous eyes of 50 children were enrolled. In bilateral cataract, only 1 eye was selected to avoid a correlation effect in statistical analyses.

METHODS

Axial length was measured by both contact and immersion techniques for all eyes, randomized as to which to perform first to avoid measurement bias.

MAIN OUTCOME MEASURES

Axial length measured by contact and immersion techniques and the difference between contact and immersion technique axial length measurements.

RESULTS

Mean age±standard deviation at cataract surgery and at axial length measurement was 3.87±3.72 years. Axial length measurement by contact technique was significantly shorter as compared with immersion technique (21.36±3.04 mm and 21.63±3.09 mm, respectively; P<0.001). Axial length measurements using the contact technique were on an average 0.27 mm shorter than those obtained using the immersion technique. Forty-two eyes (84%) had shorter axial length when measured using the contact technique as compared with the immersion technique. Lens thickness measurement by contact technique was not significantly different from that of immersion technique (3.61±0.74 and 3.60±0.67 mm, respectively; P = 0.673). Anterior chamber depth measurement was significantly more shallow with the contact technique (3.39±0.59 mm and 3.69±0.54 mm, respectively; P<0.001). Intraocular lens power needed for emmetropia was significantly different (28.68 diopters [D] vs. 27.63 D; P<0.001).

CONCLUSIONS

Contact A-scan measurements yielded shorter axial length than immersion A-scan measurements. This difference was mainly the result of the anterior chamber depth rather than the lens thickness value. During intraocular lens (IOL) power calculation, if axial length measured by contact technique is used, it will result in the use of an average 1-D stronger IOL power than is actually required. This can lead to induced myopia in the postoperative refraction.

Comparison of the biometric values obtained by two different A-mode ultrasound devices (Eye Cubed vs. PalmScan): a transversal, descriptive, and comparative study

Background

To assess the reliability of the measurements obtained with the PalmScan™, when compared with another standardized A-mode ultrasound device, and assess the consistency and correlation between the two methods.

Methods

Transversal, descriptive, and comparative study. We recorded the axial length (AL), anterior chamber depth (ACD) and lens thickness (LT) obtained with two A-mode ultrasounds (PalmScan™ A2000 and Eye Cubed™) using an immersion technique. We compared the measurements with a two-sample t-test. Agreement between the two devices was assessed with Bland-Altman plots and 95% limits of agreement.

Results

70 eyes of 70 patients were enrolled in this study. The measurements with the Eye Cubed™ of AL and ACD were shorter than the measurements taken by the PalmScan™. The differences were not statistically significant regarding AL (p < 0.4) but significant regarding ACD (p < 0.001). The highest agreement between the two devices was obtained during LT measurement. The PalmScan™ measurements were shorter, but not statistically significantly (p < 0.2).

Conclusions

The values of AL and LT, obtained with both devices are not identical, but within the limits of agreement. The agreement is not affected by the magnitude of the ocular dimensions (but only between range of 20 mm to 27 mm of AL and 3.5 mm to 5.7 mm of LT). A correction of about 0.5 D could be considered if an intraocular lens is being calculated. However due to the large variability of the results, the authors recommend discretion in using this conversion factor, and to adjust the power of the intraocular lenses based upon the personal experience of the surgeon.

Refractive outcomes with secondary intraocular lens implantation in children

PURPOSE

To determine the accuracy of postoperative predicted refractive outcomes in surgically aphakic pediatric patients undergoing secondary intraocular lens (IOL) implantation. Comparisons were also made with other variables historically considered important in cataract surgery.

METHODS

Retrospective review of 50 eyes from 35 consecutive pediatric patients (< or =18 years of age) undergoing secondary IOL implantation within the ciliary sulcus or posterior capsular bag. All cases were performed by 1 of 2 surgeons and all refractions were performed manually using the retinoscope by an experienced pediatric ophthalmologist.

RESULTS

The mean patient age at the time of the secondary implantation was 6.5 years of age (range, 0.58-15.04). The mean patient age at the time of the primary cataract extraction was 0.78 years (range, 0.08-5.77). For all patients, mean absolute value of prediction error was 1.64 D (SD 1.58 D). There were no significant associations between mean absolute value of prediction error and any of the variables measured including axial length, corneal mean curvature, bag or sulcus implantation, formula used, or age at primary and secondary surgery (p > 0.05).

CONCLUSIONS

The mean absolute value of prediction error observed in this study is consistent with previous pediatric primary and secondary IOL data in that it shows a considerable difference from that expected in adult populations. Our findings support the argument that methods currently employed to calculate IOL power may fail to accurately account for all the variations in the eyes of pediatric patients.