Influence of ocular biometric factors on the defocus curve in an enlarged depth-of-focus intraocular lens

BACKGROUND

To assess the influence of biometric measurements on the defocus curve after the implantation of enlarged depth-of-focus (EDoF) intraocular lens (IOL).

METHODS

Patients who underwent cataract surgery with bilateral implantation of Tecnis Symfony IOL were enrolled. Preoperatively, axial length (AL), corneal keratometry (K), pupil size and corneal aberrations were measured. 1 month after surgery, distance, intermediate, and near visual acuities (VA) were recorded. At 3 months, monocular and binocular corrected contrast sensitivities under photopic and mesopic lighting conditions were measured with CSV-1000E test. At 6-months, the defocus curve between -5.00 to + 3.00 diopters (D) was assessed in steps of 0.50 D, and NEI-RQL-42 questionnaire was administered.

RESULTS

One hundred thirty one eyes of 66 patients were included. Binocular logMAR VA better than 0.1 for intermediate vision was obtained in 90% of patients, whereas only 17.7% obtained that result in near vision. The rate of satisfaction was high (96%) and most of them (85.5%) had no or little difficulties in near vision. The mean amplitude of the defocus curve was 2.35D ± 0.73D, and smaller AL, smaller pupils, younger age, and male sex were associated with wider range of clear vision.

CONCLUSIONS

Tecnis Symfony IOL enables functional vision at all distances, but demographic variables and preoperative biometric measurements like AL and pupil size influence the postoperative amplitude of the defocus curve. These parameters could be used to predict the performance of EDoF IOLs.

Bias of near-infrared light in evaluation of patients implanted with multifocal intraocular lenses

PURPOSE

To compare visual quality between subjective tests and optical devices using near-infrared (NIR) light in patients implanted with monofocal, multifocal and enlarged depth-of-focus (EDoF) intraocular lenses (IOLs).

METHODS

Cross-sectional study enrolling patients aged between 55 and 75 (axial length between 22 and 25 mm) bilaterally implanted with Tecnis IOLs (Johnson & Johnson) four months previously: 40 patients (80 eyes) with monofocal ZCB00, 41 patients (82 eyes) with bifocal diffractive ZMB00 and 48 patients (96 eyes) with EDoF Symfony. They were examined using subjective and objective tests. The subjective tests comprised visual acuity (VA) with ETDRS charts, contrast sensitivity (CS) with Pelli-Robson and CSV-1000E tests, and clear vision range (CVR). The objective tests using NIR light were performed with the KR-1 W wavefront analyzer and the OQAS.

RESULTS

In the subjective tests, the monofocal group achieved the best outcomes in some of the VA and CS sections, while the bifocal group obtained the worst outcomes in some of the CS sections. In the objective tests, the bifocal group achieved the best results for VA and CS. Discrepancies between pseudoaccommodation range and CVR were found in the bifocal and EDoF groups.

CONCLUSIONS

Assessment of visual quality using NIR light implies greater bias for diffractive lenses than for EDoF lenses. This bias may be even greater with devices using longer light wavelengths or Hartmann-Shack technology. The difference in wavelength between NIR and visible light leads to dimming of near-vision focus and magnification of distance focus.

Optical aberrations in three different intraocular lens designs of a same platform

PURPOSE:

To compare internal optical aberrations between three different intraocular lenses (IOL) of the same Tecnis platform: monofocal ZCB00, multifocal ZMB00, and enlarged depth-of-focus (EDoF) Symfony ZXR00.

METHODS:

We included in this study 236 eyes of 118 patients who had been bilaterally implanted either with the monofocal, the multifocal, or the EDoF IOL. They were examined with the K1-RW wavefront analyzer (Topcon Medical Systems) 2 months after surgery. Patients with any ocular pathology were excluded from the study. Only high-order aberrations (HOA) of the third and fourth orders of the Zernike polynomials were considered.

RESULTS:

Forty-three patients (86 eyes) were implanted with the monofocal IOL, 45 patients (90 eyes) with the ZMB00 IOL, and 30 patients (60 eyes) with the EDoF Symfony IOL. Mean age was 62.42 ± 7.38, 63.60 ± 6.01, and 64.74 ± 5.84 years, respectively. Mean axial length was 23.37 ± 1.00, 23.49 ± 1.00, and 23.54 ± 0.73 mm, respectively. For a 6-mm pupil, internal total HOA in the monofocal group was 1.01 ± 1.75 μm; in the bifocal group was 1.35 ± 2.12 μm; and in the Symfony group was 0.72 ± 0.63 μm. No optical aberration differences were found among the three groups (P > 0.05).

CONCLUSION:

There are no differences regarding internal optical aberrations between these three IOLs when analyzing them with optical aberrometry. Patients’ pupil size should be considered for the selection of the most appropriate IOL to be implanted, because despite a same optical platform, every IOL implies a different increase of HOA with larger pupil sizes.

Equivalence of two optical quality metrics to predict the visual acuity of multifocal pseudophakic patients

This article studies the relationship between two metrics, the area under the modulation transfer function (MTFa) and the energy efficiency (EE), and their ability to predict the visual quality of patients implanted with multifocal intraocular lenses (IOLs). The optical quality of IOLs is assessed in vitro using two metrics, the MTFa and EE. We measured them for three different multifocal IOLs with parabolic phase profile using image formation, through-focus (TF) scanning, three R, G, B wavelengths, and two pupils. We analyzed the correlation between MTFa and EE. In parallel, clinical defocus curves of visual acuity (VA) were measured and averaged from sets of patients implanted with the same IOLs. An excellent linear correlation was found between the MTFa and EE for the considered IOLs, wavelengths and pupils (R² > 0.9). We computed the polychromatic TF-MTFa, TF-EE, and derived mathematical relationships between each metrics and clinical average VA. MTFa and EE proved to be equivalent metrics to characterize the optical quality of the studied multifocal IOLs and also in terms of clinical VA predictability.

Development of a system based on artificial intelligence to identify visual problems in children: study protocol of the TrackAI project

INTRODUCTION

Around 70% to 80% of the 19 million visually disabled children in the world are due to a preventable or curable disease, if detected early enough. Vision screening in childhood is an evidence-based and cost-effective way to detect visual disorders. However, current screening programmes face several limitations: training required to perform them efficiently, lack of accurate screening tools and poor collaboration from young children.Some of these limitations can be overcome by new digital tools. Implementing a system based on artificial intelligence systems avoid the challenge of interpreting visual outcomes.The objective of the TrackAI Project is to develop a system to identify children with visual disorders. The system will have two main components: a novel visual test implemented in a digital device, DIVE (Device for an Integral Visual Examination); and artificial intelligence algorithms that will run on a smartphone to analyse automatically the visual data gathered by DIVE.

METHODS AND ANALYSIS

This is a multicentre study, with at least five centres located in five geographically diverse study sites participating in the recruitment, covering Europe, USA and Asia.The study will include children aged between 6 months and 14 years, both with normal or abnormal visual development.The project will be divided in two consecutive phases: design and training of an artificial intelligence (AI) algorithm to identify visual problems, and system development and validation. The study protocol will consist of a comprehensive ophthalmological examination, performed by an experienced paediatric ophthalmologist, and an exam of the visual function using a DIVE.For the first part of the study, diagnostic labels will be given to each DIVE exam to train the neural network. For the validation, diagnosis provided by ophthalmologists will be compared with AI system outcomes.

ETHICS AND DISSEMINATION

The study will be conducted in accordance with the principles of Good Clinical Practice. This protocol was approved by the Clinical Research Ethics Committee of Aragón, CEICA, on January 2019 (Code PI18/346).Results will be published in peer-reviewed journals and disseminated in scientific meetings.

TRIAL REGISTRATION NUMBER

ISRCTN17316993.

Correlation between polychromatic image quality metrics to predict visual acuity in pseudophakic patients

The optical quality of three multifocal intraocular lenses (MIOLs) was measured in vitro using the area under the modulation transfer function (MTFa) and energy efficiency (EE). We evaluated those metrics through-focus (TF) by axially scanning the image space with three wavelengths (R, G, B). High linear correlation between MTFa and EE was found for all cases. Correlations between optical in vitro results (polychromatic TF-MTFa and TF-EE) and clinical visual acuity (VA) defocus curves for the three MIOLs allowed us to derive mathematical expressions. Both metrics proved to be equivalent to predict postoperative VA.

Effects of prenatal exposure to alcohol, tobacco and other drugs of abuse on retinal development

PURPOSE

To assess structural changes in the retina using optical coherence tomography (OCT) in children prenatally exposed to toxic substances.

METHODS

The study included a total of 49 infants, aged between 5 and 18years, exposed to toxic substances during pregnancy. Among the exposed children, 25 were exposed to tobacco, 20 were exposed to alcohol, and 4 children were exposed to other drugs of abuse. All children underwent a complete ophthalmology examination, including an OCT. The results were compared against a control group composed of 25 infants, age matched with controlled pregnancy, and not exposed to toxic substances.

RESULTS

Children prenatally exposed to toxic substances showed significantly thinner average retinal nerve fibre layer (RNFL) compared with control children (81.5 vs. 99.7μm; P<.005), as well as RNFL thinning in its four quadrants (superior RNFL: 97.5 vs. 127.5μm; P<.005; nasal RNFL: 61.5 vs. 72.3μm; P<.005; inferior RNFL: 99.8 vs. 128.6μm; P<.005, temporal RNFL: 58.3 vs. 68.2μm; P<.005). Exposed children also exhibited a thinner ganglion cell layer (72.9 vs. 85.9; P<.005). Greater RNFL thinning was observed in children exposed to drugs of abuse (RNFL thinner average=72), followed by children exposed to alcohol (RNFL thinner average=72.9), and finally the least affected were those children exposed to tobacco during pregnancy (RNFL=94.6).

CONCLUSION

Toxic substances during pregnancy interfere in retinal development. These results strengthen the evidence about the avoidance of any toxic substance during pregnancy.

Visual acuity of pseudophakic patients predicted from in-vitro measurements of intraocular lenses with different design

The optical quality of a set of IOLs (modeling set: one monofocal and two bifocals) was assessed through focus by the area under the modulation transfer function (MTFa) metric and related to the visual acuity (VA) defocus curves of pseudophakic patients implanted with said IOLs. A non-linear relationship between the MTFa and clinical VA was obtained with an asymptotic limit found to be the best VA achievable by the patients. Two mathematical fitting functions between clinical VA and MTFa were derived with high correlation coefficients (R²≥0.85). They were applied to the MTFa obtained from a different set of IOLs with advanced designs (trial set: one extended range of vision -ERV-, one trifocal ERV and one trifocal apodized) to predict VA versus defocus of patients implanted with these IOLs. Differences between the calculated VA and the clinical VA for both fitting models were within the standard deviation of the clinical measurements in the range of -3.00 D to 0.00 D defocus, thus proving the suitability of the MTFa metric to predict clinical VA performance of new IOL designs.

Influence of cardiovascular condition on retinal and retinal nerve fiber layer measurements

OBJECTIVE

To assess changes in the retinal nerve fiber layer (RNFL) and macula in subjects with cardiovascular risk factors or subclinical ischemia.

DESIGN

Prospective and observational study.

METHODS

A total of 152 healthy men underwent cardiovascular examination, including quantification of subclinical atheroma plaques by artery ultrasound scans, blood analysis, and a complete ophthalmic evaluation, including spectral-domain optical coherence tomography. The variables registered in cardiovascular examination were quantification of classic major risk factors, subclinical atheroma plaques by artery ultrasound scans, and analytical records. The ophthalmic evaluation registered RNFL and macular thickness.

RESULTS

Mean subject age was 51.27±3.71 years. The 40 subjects without classic cardiovascular risk factors did not show differences in RNFL and macular thicknesses compared with the 112 subjects with at least one risk factor (except in sector 9 that showed higher thicknesses in subjects with ≥1 risk factor). Comparison between the group of subjects with and without atheroma plaques revealed no differences in RNFL and macular thicknesses. The sub-analysis of subjects with subclinical atheroma plaques in the common carotid artery revealed a significant reduction in central macular thickness in the left eye compared with the right eye (p = 0.016), RNFL in the superior quadrant (p = 0.007), and the 11 o'clock sector (p = 0.020). Comparison between smokers and nonsmokers revealed that smokers had significant thinning of the central macular thickness (p = 0.034), the nasal RNFL quadrant (p = 0.006), and the 3 and 5 o'clock sectors (p = 0.016 and 0.009).

CONCLUSIONS

Classic cardiovascular risk factors do not cause RNFL or macular thickness reduction, but tobacco smoking habit reduces nasal RNFL thickness. Subclinical atherosclerosis in the common carotid artery associates a reduction in central macular and nasal RNFL quadrant thicknesses in the left eye compared with the right eye.

Face recognition impairment in small for gestational age and preterm children

BACKGROUND

Infants born prematurely or with low birth weight are at increased risk of visual perceptual impairment. Face recognition is a high-order visual ability important for social development, which has been rarely assessed in premature or low birth weight children.

AIMS

To evaluate the influence of prematurity and low birth weight on face recognition skills.

METHODS

Seventy-seven children were evaluated as part of a prospective cohort study. They were divided into premature and term birth cohorts. Children with a birth weight below the 10th centile were considered small for gestational age. All children underwent a full ophthalmologic assessment and evaluation of face recognition skills using the Facial Memory subtest from the Test of Memory and Learning.

RESULTS

Premature infants scored worse on immediate face recognition compared to term infants. However, after adjusting for birth weight, prematurity was not associated with worse outcomes. Independent of gestational age, outcomes of low birth weight children were worse than those of appropriate birth weight children, for immediate face recognition (odds ratio [OR], 5.14; 95% confidence interval [CI], 1.32-21.74) and for face memory (OR, 4.48; 95% CI, 1.14-16.95).

CONCLUSIONS

Being born small for gestational age is associated with suboptimal face recognition skills, even in children without major neurodevelopmental problems.

Effect of prematurity and low birth weight in visual abilities and school performance

BACKGROUND

Prematurity and low birth weight are known risk factors for cognitive and developmental impairments, and school failure. Visual perceptual and visual motor skills seem to be among the most affected cognitive domains in these children.

AIMS

To assess the influence of prematurity and low birth weight in visual cognitive skills and school performance.

METHODS

We performed a prospective cohort study, which included 80 boys and girls in an age range from 5 to 13. Subjects were grouped by gestational age at birth (preterm, <37 weeks; term, 37-42 weeks) and birth weight (small for gestational age (SGA), <10th centile; appropriate weight for gestational age (AGA), ≥10th centile). Each child underwent full ophthalmologic assessment and standardized testing of visual cognitive abilities (Test of Visual Perceptual Skills and Test of Visual Analysis Skills). Parents completed a questionnaire on school performance in children.

RESULTS

Figure-ground skill and visual motor integration were significantly decreased in the preterm birth group, compared with term control subjects (figure-ground: 45.7 vs 66.5, p=0.012; visual motor integration, TVAS: (9.9 vs 11.8, p=0.018), while outcomes of visual memory (29.0 vs 47.7, p=0.012), form constancy (33.3 vs 52.8, p=0.019), figure-ground (37.4 vs 65.6, p=0.001), and visual closure (43.7 vs 62.6 p=0.016) testing were lower in the SGA (vs AGA) group. Visual cognitive difficulties corresponded with worse performance in mathematics (r=0.414, p=0.004) and reading (r=0.343, p=0.018).

CONCLUSION

Specific patterns of visual perceptual and visual motor deficits are displayed by children born preterm or SGA, which hinder mathematics and reading performance.

Microstructural changes in the retina related to prematurity

PURPOSE

To assess retinal morphology changes in patients born at different stages of prematurity, accounting for the presence or absence of retinopathy of prematurity (ROP) and comorbidity, using spectral-domain optical coherence tomography (SD OCT).

DESIGN

Retrospective cohort study.

METHODS

Preterm and term infants underwent an ophthalmologic assessment (best-corrected visual acuity, stereoacuity, cycloplegic refraction and funduscopy). Retinal layers were imaged, segmented, and measured by SD-OCT. In total 114 full term controls and 60 preterm children, classified as late preterm (32-36 weeks gestational age), early preterm (<32 weeks of gestational age) without ROP, and early preterm with previously treated ROP, were included in the study.

RESULTS

No retinal structure differences were observed in preterm infants with no treated ROP compared to term infants. Early preterm infants with previous treated ROP had decreased retinal nerve fiber layer (RNFL) thickness in the superior and nasal quadrants, increased RNFL in the temporal quadrant, and a thinner ganglion cell and inner plexiform layer complex (GCL-IPL). Low birthweight percentile was associated with increased foveal thickness and ganglion cell damage (RNFL and GCL-IPL) independent of gestational age. Among all the coexisting events, inflammation and hypoxia were correlated with more severe detrimental effects.

CONCLUSIONS

In the absence of treated ROP, prematurity was not associated with disturbed retinal structure. Severe ROP and low birthweight were related to neuronal and axonal damage in the inner retinal layers. Detailed comorbidity should be reviewed when evaluating preterm infants.

Retinal asymmetry in children measured with optical coherence tomography

PURPOSE

To determinate the physiological asymmetry of retinal measurements in the pediatric population with Fourier-domain optical coherence tomography (Cirrus HD-OCT).

DESIGN

Prospective cross-sectional study.

METHODS

Three hundred and fifty-seven healthy children were recruited. All subjects underwent a comprehensive ophthalmologic examination and an evaluation of the retinal nerve fiber layer (RNFL), optic nerve head, and macula with Cirrus OCT. Differences between right and left eyes were calculated and values were compared by means of a paired t test. Normal ranges of interocular differences were established as the 2.5th and the 97.5th percentiles. The correlations between right and left eyes were assessed by the intraclass correlation coefficients.

RESULTS

Mean best-corrected visual acuity (logMAR) was -0.01. Differences in the average RNFL between right and left eyes were not statistically significant. The RNFL in the right eyes was thicker in the temporal and nasal quadrants, whereas the left eyes showed thicker RNFL in the superior quadrant. The interocular difference tolerance limits for average RNFL and macular thicknesses were 13.00 μm and 23.20 μm, respectively. There was a strong correlation for all the parameters between the right and the left eyes.

CONCLUSIONS

The asymmetry of retinal parameters might be more valuable than the absolute values in assessing certain early diseases. The interocular differences in average RNFL and macular thickness of normal individuals should not exceed 13 μm and 23 μm, respectively, if measured with Cirrus HD-OCT.

Reproducibility of optical coherence tomography measurements in children

PURPOSE

To determine the interobserver and intraobserver reproducibility of a Fourier-domain optical coherence tomography device (Cirrus HD OCT; Carl Zeiss Meditec, Dublin, California, USA) in normal pediatric eyes.

DESIGN

Prospective cross-sectional study.

METHODS

One hundred healthy children were recruited prospectively and consecutively. Only 1 randomly chosen eye per subject was included in the study. The eye underwent 3 scans centered on the optic disc and another 3 scans centered on the macula that were acquired by a single operator. A fourth examination was performed by a second operator. Interobserver and intraobserver reproducibility were described by intraclass correlation coefficients (ICCs) and coefficients of variation (COVs).

RESULTS

The mean age was 9.15 years (range, 6.22 to 11.31 years; standard deviation, 1.05 years). Mean retinal nerve fiber layer thickness was 99.53 μm (standard deviation, 10.10 μm), and mean macular thickness was 282.91 μm (standard deviation, 11.83 μm). All the parameters evaluated were highly reproducible. Intraobserver COVs of the retinal nerve fiber layer measurements ranged from 2.24% to 5.52%, and the COV of macular thickness was 0.97%. The intraclass correlation coefficient was greater than 0.8 for all the parameters. The interobserver COV ranged from 2.23% to 5.18%, and the COV of macular thickness was 0.82%. In all the evaluated parameters, the intraclass correlation coefficient was more than 0.75. Repeatability was slightly better in children older than 10 years than in children younger than 9 years.

CONCLUSIONS

Retinal nerve fiber layer and macular measurements obtained by Fourier-domain optical coherence tomography showed good repeatability for healthy eyes in the pediatric population. Cirrus HD OCT examinations of the retina are reliable in children.