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

Anterior Chamber Depth and Lens Thickness Measurements in Pediatric Eyes: Ultrasound Biomicroscopy Versus Immersion A-Scan Ultrasonography

OBJECTIVE

To compare anterior chamber depth (ACD) and lens thickness (LT) measurements by ultrasound biomicroscopy (UBM), A-scan cross vector (CV) overlay with UBM, and immersion A-scan technique in pediatric eyes.

METHODS

This prospective comparative cohort study comprised 43 eyes of 25 pediatric participants (mean age: 2.3±2.2 y). UBM and immersion A-scan biometry were performed prior to dilation and intraocular surgery. ACD and LT were measured by UBM image analysis, A-scan CV UBM overlay, and immersion A-scan technique.

RESULTS

ACD and LT measurements obtained using immersion A-scan were significantly greater than with UBM image analysis with mean differences of 0.52 mm and 0.62 mm, respectively (p < 0.001). Immersion A-scan and UBM measurements were moderately correlated (r = 0.70 and 0.64, p < 0.001). ACD and LT measurements obtained using CV overlay were not significantly different than UBM measurements and the values were strongly positively correlated (r = 0.95 and 0.93, p < 0.001).

CONCLUSION

Immersion A-scan may overestimate ACD and LT compared to UBM in pediatric patients due to oblique placement of the A-scan probe relative to the optical axis. Supplemental use of UBM and/or CV overlay is indicated to improve measurement accuracy in pediatric patients who cannot reliably fixate due to the ability to confirm proper alignment of the probe with the pupil by visualizing the anterior segment.

A Morphometric Study of the Pars Plana of the Ciliary Body in Human Cadaver Eyes

This study aimed to determine the pars plana length in postmortem human eyes using advanced morphometric techniques and correlate demographics to ocular metrics such as age, sex, ethnicity, and axial length. Between February and July 2005, we conducted a cross-sectional observational study on 46 human cadaver eyes deemed unsuitable for transplant by the SBO Eye Bank. The morphometric analysis was performed on projected images using a surgical microscope and a video-microscopy system with a 20.5:1 correction factor. The pars plana length was measured three times per quadrant, with the final value being the mean of these measurements. Of the 46 eyes collected, 9 were unsuitable for the study due to technical constraints in conducting intraocular measurements. Overall, the average axial length was 25.20 mm. The average pars plana length was 3.8 mm in all quadrants, with no measurements below 2.8 mm or above 4.9 mm. There were no statistically significant variations across quadrants or with age, sex, axial length, or laterality. Accurately defining the pars plana dimensions is crucial for safely accessing the posterior segment of the eye and minimizing complications during intraocular procedures, such as intravitreal injections and vitreoretinal surgeries.

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.

Long-term Results of Congenital Cataract Surgery with Primary Intraocular Lens Implantation: A Case-Control Study of Three Age Groups

Purpose

To analyze the results of ocular refraction at the age of 7 years in children after congenital cataract surgery with intraocular lens (IOL) implantation.

Methods

A study of ocular biometric data of 143 eyes who underwent lens aspiration with IOL implantation in unilateral (23 eyes) and bilateral (60 eyes) congenital cataracts was performed. All children were divided into groups according to the age categories at the time of surgery: Group A (0-12 months) - 43 eyes; Group B (12-36 months) - 45 eyes; and Group C (older than 36 months) - 55 eyes. An empirical reduction of the implanted IOL power was performed: an undercorrection of 20% in children aged 0 to 36 months and 10% less in children aged 36 to 60 months.

Results

By age 7 years, the mean elongation ± standard deviation (SD) in Group A was 3.93 ± 1.64 mm, 2.13 ± 0.94 mm in Group B, and 0.95 ± 0.76 mm in Group C (18.7%, 9.5%, and 4.1% of the baseline axial length, respectively). There was no significant difference in axial elongation between unilateral and bilateral congenital cataracts (P = 0.32). The mean absolute refraction error (MAE) at last examination was 3.99 ± 2.12 diopter (D), 2.46 ± 1.48 D, and 1.59 ± 1.31 D in Groups A, B, and C, respectively. In infants younger than 7 months of age, by age 7 years, the mean elongation ± SD was 3.27 ± 2.86 mm (25.5%) and MAE was 3.44 ± 2.1 D. The prevalence of preoperative corneal astigmatism of 1.0 D or more was 48.95%, 2.0 D or more was 27.27%, and 3.0 D or more was 5.6%. There was no significant difference in preoperative corneal astigmatism between unilateral (1.62 ± 0.77 D) and bilateral (1.78 ± 0.90 D) congenital cataracts (P = 0.56, 95% confidence interval = -0.50-0.28). Best-corrected visual acuity (BCVA) more than 20/40 was in 53.49%, 55.55%, and 74.54% in Groups A, B, and C, respectively.

Conclusions

Although IOL power was calculated in accordance with children's age, at the age of 7 years, there was a different degree of ametropia because of the biometric changes of the growing eye, and a higher rate of ametropia was observed more in the younger age group than in the elder age groups.

Deviations From Age-Adjusted Normative Biometry Measures in Children Undergoing Cataract Surgery: Implications for Postoperative Target Refraction and IOL Power Selection

PURPOSE

To evaluate whether pediatric eyes that deviate from age-adjusted normative biometry parameters predict variation in myopic shift after cataract surgery.

METHODS

This is a single institution longitudinal cohort study combining prospectively collected biometry data from normal eyes of children <10 years old with biometry data from eyes undergoing cataract surgery. Refractive data from patients with a minimum of 5 visits over ≥5 years of follow-up were used to calculate myopic shift and rate of refractive growth. Cataractous eyes that deviated from the middle quartiles of the age-adjusted normative values for axial length and keratometry were studied for variation in myopic shift and rate of refractive growth to 5 years and last follow-up visit. Multivariable analysis was performed to determine the association between myopic shift and rate of refractive growth and factors of age, sex, laterality, keratometry, axial length, intraocular lens power, and follow-up length.

RESULTS

Normative values were derived from 100 eyes; there were 162 eyes in the cataract group with a median follow-up of 9.6 years (interquartile range: 7.3-12.2 years). The mean myopic shift ranged from 5.5 D (interquartile range: 6.3-3.5 D) for 0- to 2-year-olds to 1.0 D (interquartile range: 1.5-0.6 D) for 8- to 10-year-olds. Multivariable analysis showed that more myopic shift was associated with younger age (P < .001), lower keratometry (P = .01), and male gender (P = .027); greater rate of refractive growth was only associated with lower keratometry measures (P = .001).

CONCLUSIONS

Age-based tables for intraocular lens power selection are useful, and modest adjustments can be considered for eyes with lower keratometry values than expected for age.

The accuracy of intraocular lens calculation varies by age in the Infant Aphakia Treatment Study

Refraction predictions from intraocular lens (IOL) calculation formulae are inaccurate in children. We sought to quantify the relationship between age and prediction error using a model derived from the biometry measurements of children enrolled in the Infant Aphakia Treatment Study (IATS) when they were ≤7 months of age. We calculated theoretical predicted refractions in diopters (D) using axial length, average keratometry, and IOL powers at each measurement time point using the Holladay 1 formula. We compared the predicted refraction to the actual refraction and calculated the absolute prediction error (APE). We found that the median APE was 1.60 D (IQR, 0.73-3.11 D) at a mean age (corrected for estimated gestational age) of 0.20 ± 0.14 years and decreased to 1.11 D (IQR, 0.42-2.20 D) at 10.60 ± 0.27 years. We analyzed the association of age with APE using linear mixed-effects models adjusting for axial length, average keratometry, and IOL power and found that as age doubled, APE decreased by 0.25 D (95% CI, 0.09-0.40 D). The accuracy of IOL calculations increases with age, independent of biometry measurements and IOL power.

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.].

Axial Length Changes Following Surgical Intervention in Children With Primary Congenital Glaucoma

Background

Primary congenital glaucoma (PCG) is a challenging condition to diagnose, treat and effectively monitor. Serial assessment of intraocular pressure (IOP), optic disc cupping, refraction, and axial length (AxL) after surgery are useful to assess disease control. This study aimed to evaluate AxL changes in relation to IOP changes following glaucoma surgery in children with PCG.

Methods

We retrospectively studied AxL changes in children with PCG undergoing surgery. Eyes of children aged ≤ 4 years that did not have prior ocular surgery and that underwent at least one glaucoma surgery during the course of follow-up between June 2014 and July 2018, were included. The effect of change in IOP on change in AxL was estimated using linear mixed effects models.

Results

A total of 105 eyes (of 72 children) with PCG underwent glaucoma surgery representing 26.4% (105/397) eyes. The mean ± SD age of children at baseline was 3.53 ± 4.04 months. At baseline, the mean IOP and AxL were 26.63 ± 9.57 mmHg and 21.67 ± 1.82 mm, respectively. During the course of follow-up post-surgery, the IOP decreased by a mean of 7.25 ± 12.08 mmHg while the AxL increased by a mean of 0.70 ± 1.40 mm. A multivariable mixed effects linear regression revealed that change in AxL was significantly associated with change in IOP (p=0.030) and time since first surgery (p<0.001). A substantial reduction in IOP (≥35 mmHg) was needed at 3 months post-surgery, for AxL to regress.

Conclusion

In children with PCG who undergo glaucoma surgery, change in IOP significantly influences change in AxL. For AxL to regress, a substantial reduction in IOP is needed post-surgery.

Efficacy of Swept-source Optical Coherence Tomography in Axial Length Measurement for Advanced Cataract Patients

SIGNIFICANCE

A major limitation of standard time-domain optical coherence tomography-based biometers (TD-OCT) is an inability to measure the axial length (AL) in advanced cataract. A new device that uses swept-source optical coherence tomography (SS-OCT) allows better light penetration. Hence, a considerable number of cataract patients who failed AL measurement by TD-OCT can be recovered by SS-OCT.

PURPOSE

The purposes of this study were to evaluate the efficacy of an SS-OCT for AL measurement in advanced cataract patients and to identify characteristics of lens opacity that impede the AL measurement.

METHODS

Advanced cataract patients who were unable to obtain AL measurement using a standard TD-OCT-based optical biometer (IOLMaster500; Carl Zeiss Meditec, Jena, Germany) were recruited in this study. The AL was remeasured using SS-OCT (IOLMaster700), followed by measurement with immersion ultrasonography (IU). The percentage of patients who achieved AL measurement by SS-OCT was recorded. The AL obtained from SS-OCT was then verified by comparing with the AL derived from IU. The cataract type of each patient was classified according to standard Lens Opacity Classification III score. The association between characteristics of cataract and successful AL measurement by SS-OCT was analyzed.

RESULTS

Sixty-four eyes that failed AL measurement from TD-OCT were included. Fifty-six eyes (87.5%) were able to be measured by SS-OCT (95% confidence interval, 77.23 to 93.53%). The AL obtained by SS-OCT showed very high agreement with those derived from IU (intraclass correlation coefficient, 0.99). There was no statistically significant correlation between characteristics of lens opacity and the capability of SS-OCT for AL measurement (P > .05). However, there was a trend toward an inability to measure the AL in cataracts with a high grade of lens opacity.

CONCLUSIONS

The efficacy of SS-OCT-based optical biometer was excellent. Of the patients with advanced cataract who failed the AL measurement by TD-OCT, 87.5% could be recovered by SS-OCT. However, there was no specific type of lens opacity associated with a failure of AL measurement using SS-OCT.

Topical Review: Causes of Refractive Error After Silicone-oil Removal Combined with Cataract Surgery

SIGNIFICANCE

This review summarizes the main factors of refractive error after silicone oil removal combined with cataract surgery.The post-operative refractive results of silicone oil removal combined with cataract surgery are closely related to the patient's future vision quality. This report summarizes the factors that influence the difference between the actual post-operative refractive power and the pre-operatively predicted refractive power after silicone oil removal combined with cataract surgery, including axial length, anterior chamber depth, silicone oil, commonly used tools for measuring intraocular lens power, and intraocular lens power calculation formulas, among others. The aim of the report is to assist clinical and scientific research on the elimination of refractive error after silicone oil removal combined with cataract surgery.

Comparison of Aphakic Refraction and Biometry-Based Formulae for Secondary In-The-Bag and Sulcus-Implanted Intraocular Lens Power Estimation in Children

PURPOSE

The aim of the study was to compare the accuracy of refractive outcomes in children undergoing secondary in-the-bag or cilliary sulcus intraocular lens (IOL) implantation, using aphakic refraction (AR)-based formulae (Hug and Khan) and biometry-based formulae (Holladay 1, Hoffer Q, SRK/T, and SRK II).

METHODS

In this retrospective study, a total of 65 eyes of 44 patients who underwent secondary in-the-bag or cilliary sulcus IOL implantation were included and divided into 2 groups: 39 eyes of the in-the-bag IOL group and the other 26 eyes of the sulcus-implanted IOL group. Holladay 1, Hoffer Q, SRK/T, and SRK II formulae were employed depending on the biometric data, while Hug and Khan formulae were used based on preoperative AR. The prediction error (PE) and the absolute value of predicted error (APE) were compared between the 2 groups and formulae.

RESULTS

In the in-the-bag IOL group, nonsignificant differences of APE were found among the 6 formulae, while the Holladay 1, Hoffer Q, SRK/T, and SRK II all demonstrated a significant hyperopic shift of median PE value compared to the Hug formula (p < 0.05, all), and Holladay 1 and SRK II also showed a significant hyperopic shift of PE compared to the Khan formula (p < 0.05, both). Higher percentages of eyes with PE <1 D were found using Hoffer Q and SRK/T. In the sulcus-implanted group, the Holladay 1, Hoffer Q, and SRK/T had a significantly smaller median value of APE than the Hug and Khan formulae (p < 0.05, all), and the SRK II had a significantly smaller median value of APE than the Hug formula (p < 0.05), while Holladay 1 had the lowest value of APE. Higher percentages of eyes within PE <1 D were found using Holladay 1, Hoffer Q, and SRK/T, while the highest one was SRK/T. Significantly larger hyperopic shifts of median PE value using all the 6 formulae were found in eyes with sulcus-implanted IOL than eyes with in-the-bag implanted IOL (p < 0.05, all). In the eyes of with in-the-bag implanted IOL, the Hug and Khan formulae had significantly smaller APE values when compared with the eyes with sulcus-implanted IOL (p < 0.05, both).

CONCLUSIONS

Whether IOL was in the bag or implanted in the sulcus, almost all the formulae showed hyperopic shift, SRK/T showed the best accuracy. Biometry-based formulae were superior to AR-based formulae in accuracy of IOL power calculation, especially when IOL was implanted in the sulcus. In-the-bag IOL implantation should always be with higher priorities, especially when using AR-based formulae in IOL power calculation.

Predicting future axial length in patients with paediatric cataract and primary intraocular lens implantation

OBJECTIVE

Creating a model to predict Axial Length (AL) growth in paediatric cataract and evaluating influence factors.

MATERIAL AND METHODS

Eyes with AL measured at surgery and at least one measurement after a 6-month period, from children with unilateral or bilateral cataract and primary IOL implantation, were evaluated. A "rate of axial length growth" (RALG) was calculated for every single eye using these AL measurements and log₁₀ age. One average RALG was calculated for All Eyes and for the groups of Bilateral and Unilateral, Gender, Age at the Surgery, different Visual Acuity, Bilateral Excluded and Not-excluded eye, and Affected and Not-affected eye in unilateral, for comparisons.

RESULTS

Average age at surgery from 76 children was 2.83 ± 2.74 (0.11-12.21) years with follow up of 2.84 ± 1.84 (0.52-8.17) years, 29 (37.66%) had unilateral cataract. A total of 357 AL measurements were used, average of 4.70 ± 2.13 (2-10) measurements per eye. The average RALG for all eyes was 4.51 ± 3.06. There were no RALG significant differences comparing Unilateral and Bilateral eyes (p = 0.51), Male and Female (p = 0.26), Age at Surgery <0.5 and >0.5 years old (p = 0.21), both eyes in Bilateral cases (p = 0.70) and Unilateral Affected and Not-affected eyes (p = 0.18). The equation Al = initial AL + slope ×  Log₁₀ ((age + 0.6)⁄(initial age + 0.6)) estimates ALs in different ages.

CONCLUSIONS

A model to predict AL growth in paediatric cataract was developed. Different studied factors did not significantly influence AL growth.

Effect of Age at Primary Intraocular Lens Implantation on Refractive Growth in Young Children

PURPOSE

To evaluate the effect of age at primary intraocular lens (IOL) implantation on rate of refractive growth (RRG3) during childhood.

METHODS

A retrospective chart review was performed for children undergoing primary IOL implantation during cataract surgery. RRG3 was calculated for one eye from each patient using the first postoperative refraction, last refraction that remained stable (< 1.00 diopters [D] change/2 years), and the corresponding ages. RRG3 values for pseudophakic patients operated on from ages 0 to 5 months were compared with values for patients operated on at ages 6 to 23 months and 24 to 72 months. Patients with refractive errors that stabilized were grouped by age at surgery to compare age at refractive plateau.

RESULTS

Of 296 eyes identified from 219 patients, 46 eyes met the inclusion criteria. There was a statistically significant difference in RRG3 among age groups. The mean RRG3 value was -19.82 ± 5.23 D for the 0 to 5 months group, -22.32 ± 7.45 D for the 6 to 23 months group (0 to 5 months vs 6 to 23 months, P = .43), and -9.64 ± 11.95 D for the 24 to 72 months group (0 to 5 months vs 24 to 72 months, P = .01).

CONCLUSIONS

Age at primary IOL implantation affects the RRG3, especially for children 0 to 23 months old at surgery. Surgeons performing primary IOL implantation in infants may want to use age-adjusted assumptions, because faster refractive growth rates can be expected in young children. [J Pediatr Ophthalmol Strabismus. 2020;57(4):264-270.].

IMI - Clinical Myopia Control Trials and Instrumentation Report

The evidence-basis based on existing myopia control trials along with the supporting academic literature were reviewed; this informed recommendations on the outcomes suggested from clinical trials aimed at slowing myopia progression to show the effectiveness of treatments and the impact on patients. These outcomes were classified as primary (refractive error and/or axial length), secondary (patient reported outcomes and treatment compliance), and exploratory (peripheral refraction, accommodative changes, ocular alignment, pupil size, outdoor activity/lighting levels, anterior and posterior segment imaging, and tissue biomechanics). The currently available instrumentation, which the literature has shown to best achieve the primary and secondary outcomes, was reviewed and critiqued. Issues relating to study design and patient selection were also identified. These findings and consensus from the International Myopia Institute members led to final recommendations to inform future instrumentation development and to guide clinical trial protocols.

Comparison of immersion ultrasound and low coherence reflectometry for ocular biometry in cataract patients

AIM

To compare the results of axial length (AL) biometry in cataract eyes by three methods: immersion B-ultrasound (IB) biometry, immersion A-ultrasound (IA) biometry and optical low coherence reflectometry.

METHODS

In this prospective observational study of eyes with cataract AL measurements were performed using immersion ultrasound and optical low coherence reflectometry device. The results were evaluated using Bland-Altman analyses. The differences between both methods were assessed using the paired t-test, and its correlation was evaluated by Pearson coefficient.

RESULTS

Eighty eyes of 80 patients (39 men and 41 women) for cataract surgery were included in the study. The values of AL could be got from all 80 eyes by IB and IA, the difference of AL measurements between IA and IB was of no statistical significance (P=0.97); the mean difference in AL measurements was -0.031 mm (P=0.26; 95%CI, -0.09 to 0.02); linear regression showed an excellent correlation (r=0.98, P<0.0001). Forty-five of eighty eyes with results of AL measurements, which can be obtained by three methods; the difference of AL measurements was of no statistical significance (IA vs IB, P=0.18; IA vs Lenstar, P=0.51; IB vs Lenstar, P=0.07); linear regression showed an excellent correlation (IA vs IB, r=0.99; IA vs Lenstar, r=0.96; IB vs Lenstar, r=0.96); Bland-Altman analysis also showed good agreement between the two methods [IA vs IB, 95% limits of agreement (LoA), -0.36 to 0.28 mm; IA vs Lenstar, 95% LoA, -0.65 to 0.69 mm; IB vs Lenstar, 95% LoA, -0.55 to 0.68 mm].

CONCLUSION

Measurements with the optical low coherence reflectometry correlated well with IB and IA. In the eyes with serious refractive medium opacity, the measurements of AL could not be achieved or existed deviations when using optical low coherence reflectometry device. Under such circumstances, we should choose IA or IB as the optimization method to obtain measurements, in order to get much more accurate results.

Precision of a new ocular biometer in children and comparison with IOLMaster

To assess the repeatability and reproducibility of AL-Scan in agreement with those by the IOLMaster in healthy children, two skilled operators measured ocular parameters in 58 children. The parameters included keratometry (K) values, anterior chamber depth (ACD), axial length (AL), central corneal thickness (CCT), pupil diameter (PD), and corneal diameter (CD). The cohort comprised of 32 boys and 26 girls. The AL-Scan measurements showed high repeatability, as the test-retest repeatability (TRT) values of AL, CCT, ACD, Kf, Ks, Km, CD, and PD were 0.09 mm, 5.1 μm, 0.04 mm, 0.28 D, 0.24 D, 0.21 D, 0.39 mm, and 0.22 mm, respectively. The within-subject coefficient of variation (CoV) was low (<0.35%) and the intraclass correlation coefficients (ICC) of all parameters were >0.85. The interobserver reproducibility was excellent with low values of TRT and ICC > 0.95. The CoV of AL, CCT, ACD, and K was <0.22%. The 95% limits of agreement between the AL-Scan and the IOLMaster were narrow for all parameters except for CD. The repeatability and reproducibility of the new biometer, Al-Scan, was excellent for all parameters and can be routinely used in children to measure the biometric values.

Analysis of Factors Associated with the Ocular Features of Congenital Cataract Children in the Shanghai Pediatric Cataract Study

Purpose

To investigate the ocular features of children with congenital cataract in a tertiary referral eye center in East China.

Methods

We retrospectively reviewed the clinical data of congenital cataract children who underwent cataract surgery between April 2009 and April 2014 at the Eye and ENT Hospital of Fudan University and identified factors associated with the axial length (AXL) and corneal curvature (K value).

Results

We included 493 children, 210 with unilateral and 283 with bilateral cataract. The mean AXL was 22.03 ± 1.97 mm and the mean K value was 43.61 ± 1.86 D. Age showed a linear correlation with AXL in unilateral cataract eyes and a logarithmic correlation with AXL in bilateral cataract eyes (both P < 0.001). AXL was longer and the K value was smaller (both P < 0.01) in boys than in girls after adjusting for age and cataract laterality. AXL was longer in unilateral cataract eyes than in bilateral cataract eyes after adjusting for age and gender (P = 0.004). In children with unilateral cataract, AXL was significantly longer in the affected eye than in the contralateral eye (P < 0.001).

Conclusion

Age, gender, and cataract laterality together contribute to the development of ocular features of congenital cataract children, especially for AXL.

In Vivo Positional Analysis of Implantable Collamer Lens Using Ultrasound Biomicroscopy

Purpose. To evaluate the anterior segment, the anatomical position of the implantable collamer lenses (ICL), and its relationship to adjacent ocular structures using Ultrasound Biomicroscopy (UBM). Methods. In a prospective study, 142 myopic eyes of 93 patients implanted with Visian ICL were subjected to UBM examination between March 2010 and January 2015. The relative position of ICL to the adjacent structure and the overall iris configuration were evaluated. The machine calibers were used to measure the minimum central distance between the ICL and anterior lens capsule (vault) and the vertical central distance between the corneal endothelium and the ICL (E-ICL). Results. The mean ICL vault was 376 ± 105 μm. The mean E-ICL was 2826 ± 331 μm. Contact between ICL and the posterior epithelium of the iris was present in all eyes. The overall iris configuration was flat in 89 eyes. Central anterior convexity was present in 41 eyes and mild peripheral iris bombe in 12 eyes. The haptics could be imaged in the ciliary sulcus in 112 eyes and at least one haptic resting on the lens periphery and zonules in 30 eyes. Conclusion. UBM can provide valuable anatomical information that allows detailed postoperative in vivo assessment of ICL.

Paediatric intraocular lens implants: accuracy of lens power calculations

PurposeThis study aims to evaluate the accuracy of lens prediction formulae on a paediatric population.MethodsA retrospective case-note review was undertaken of patients under 8 years old who underwent cataract surgery with primary lens implantation in a regional referral centre for paediatric ophthalmology, excluding those whose procedure was secondary to trauma. Biometric and refractive data were analysed for 43 eyes, including prediction errors (PE). Statistical measures used included mean absolute error (MAE), median absolute error (MedAE), Student's t-test and Lin's correlation coefficient.ResultsThe mean PE using the SRK-II formula was +0.96 D (range -2.47D to +2.41 D, SD 1.33 D, MAE 1.38 D, MedAE 1.55, n=15). The mean PE was smaller using SRK/T (-0.18 D, range -3.25 D to +3.95 D, SD 1.70 D, MAE 1.30 D, MedAE 1.24, n=27). We performed an analysis of the biometry data using four different formula (Hoffer Q, Holladay 1, SRK-II and SRK/T). Hoffer Q showed a smaller MedAE than other formulae but also a myopic bias.ConclusionOur clinical data suggest SRK/T was more accurate in predicting post-operative refraction in this cohort of paediatric patients undergoing cataract surgery. Hoffer Q may have improved accuracy further.

Distribution of Axial Length before Cataract Surgery in Chinese Pediatric Patients

Axial length (AL) is a significant indicator of eyeball development, but reports on the overall status of axial development in congenital cataract (CC) patients and its relationship with patient demographics, such as age, sex, and laterality, are rare. We prospectively investigated the AL of 1,586 patients ≤18 years old and undergoing cataract surgery in China from January 2005 to December 2014. Of these 3,172 eyes, a logarithmic correlation between AL and age in CC patients was calculated, and an age of approximately 2 years was found to be a turning point in the growth rate of AL. A considerable variation was observed in CC patients of the same age. Furthermore, 2–6 years old boys had longer AL than girls. The AL of affected eye in unilateral patients was longer than that of the contralateral eye in 2–6 years age group and longer than that of eye in bilateral CC patients in all age groups. These findings indicate that the development of the length of eyeballs in CC patients is influenced by multiple factors in addition to age. A full understanding of the distribution of AL may provide a useful reference for judging the timing of surgery in CC patients.

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.

Axial length measurement techniques in pediatric eyes with cataract

Globe axial length (AL) in children is commonly measured using either contact or immersion technique. Office measurement of AL can be difficult in young children and infants and must often be done under anesthesia in an eye that is unable to cooperate with precise fixation and centration. Contact A-scan measurements yield shorter AL, on average, than immersion A-scan measurements in pediatric eyes. This difference is mainly the result of the anterior chamber depth rather than the lens thickness value. During intraocular lens power calculation, if globe axial length is measured by the contact technique, 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. In our studied patients, there was a significant difference in prediction error between contact A-scan biometry and immersion A-scan biometry. The immersion A-scan technique is recommended for pediatric IOL power calculation. We also provide a review of biometry in pediatric eyes. The overall mean AL of pediatric cataractous eyes is significantly different than the mean AL of non cataractous eyes. More importantly, the standard deviation is higher in eyes with cataract than in those without. Three phases of eye growth in children have been documented: A rapid, postnatal phase from birth to 6 months of age, followed by a slower, infantile phase from 6 to 18 months of age, and finally a slow, juvenile phase from 18 months forward. In our study, girls had shorter ALs than boys and African-American subjects had longer ALs than Caucasians. Eyes with unilateral cataract had shorter ALs than eyes with bilateral cataract during the earlier years, but had longer ALs during later childhood.

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.

Refractive outcomes and prediction error following secondary intraocular lens implantation in children: a decade-long analysis

AIM

To evaluate the refractive outcomes, prediction error (PE) and factors affecting PE in children with aphakia following congenital cataract surgery undergoing secondary intraocular lens (IOL) implantation.

METHODS

We analysed the records of children less than 16 years old who underwent secondary IOL implantation for aphakia following congenital cataract surgery. PE and absolute PE for each case calculated 3 months following secondary IOL implantation were analysed. Multiple regression analysis was performed to determine the relationship between age at secondary IOL implantation, axial length, keratometry readings and PE.

RESULTS

174 eyes of 104 children were analysed. Mean age at surgery was 6.08±3.75 years. The mean PE was 1.65±2.46 dioptres (D) (range -3.25 to 7.5 D) and mean absolute PE was 2.15±1.68 D (range 0-7.5 D) at 3 months. There was a statistically significant difference in absolute PE between eyes in which IOL calculation was performed using IOL master (1.80±1.40 D) versus IOL calculation under general anaesthesia with contact method (2.43±1.83 D), p=0.01. Multiple regression analysis revealed an inverse relationship between age at secondary IOL implantation and mean absolute PE (p=0.01).

CONCLUSIONS

IOL power calculation with SRK II formula with sulcus placement of IOL gives favourable refractive outcomes. Though age-based refraction is targeted, a significant PE may be expected.

Axial elongation following cataract surgery during the first year of life in the infant Aphakia Treatment Study

PURPOSE

To compare ocular axial elongation in infants after unilateral cataract surgery corrected with a contact lens (CL) or primary intraocular lens (IOL) implantation.

METHODS

Baseline axial length (AL) was measured at the time of cataract surgery (1-6 months) and at age 1 year. AL at baseline and age 1 year and the change in length/mo were analyzed in relation to treatment modality, cataractous versus fellow eye, and age at surgery using linear mixed models.

RESULTS

Mean baseline AL did not differ between the CL and IOL groups for either cataractous or fellow eyes. Eyes with cataracts were shorter than fellow eyes by an average of 0.6 mm (95% confidence interval [CI], 0.4-0.8 mm; P < 0.0001). For the operated eyes, the mean change in AL/mo was smaller in the CL group (0.17 mm/mo) than in the IOL group (0.24 mm/mo) (P = 0.0006) and was independent of age at surgery (P = 0.19). In contrast, the change in AL/mo for fellow eyes decreased with older age at surgery (P < 0.0001). At age 1 year, operated eyes treated with a CL were 0.6 mm shorter on average than operated eyes treated with an IOL (P = 0.009).

CONCLUSIONS

At baseline, eyes with cataracts were shorter than fellow eyes. The change in AL/mo was smaller in operated eyes treated with a CL than in operated eyes treated with an IOL, but was not significantly related to age at surgery. (ClinicalTrials.gov number, NCT00212134.).

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.

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.

Modern cataract surgery: unfinished business and unanswered questions

We summarize information, based on clinicopathologic studies over the past decade, on various cataract intraocular lens (IOL) procedures and modern "specialized" IOLs, that will help surgeons continuously improve long-term results for cataract patients. Although most operations do initially provide excellent refractive correction and visual rehabilitation, late complications occur. These sometimes are missed because they are outside of the routine period of follow-up care. We have tried to determine if the various techniques and IOLs truly deliver the long-term results that we desire. Most safety and efficacy information is derived from the manufacturer and is passed through the U.S. Food and Drug Administration (FDA). This is often based on limited, relatively short-term observations made by the manufacturer. After a lens receives FDA approval, there are few means to assess the outcome of each procedure and lens years later. We rarely hear of a 10- or 20-year follow-up study. We have found that one of the best means to assess long-term results is pathologic analyses. We discuss recently studied aspects of pathologic reactions, such as posterior capsule opacification, intracapsular fibrosis, glistenings, intralenticular opacification, and other issues with the various IOL platforms; we then present a clinicopathological overview of tissues and IOLs from our database. These include hydrophobic and hydrophilic acrylic designs, plate lenses, and a dual optic lens.