Extended optical treatment versus early patching with an intensive patching regimen in children with amblyopia in Europe (EuPatch): a multicentre, randomised controlled trial

BACKGROUND

Amblyopia, the most common visual impairment of childhood, is a public health concern. An extended period of optical treatment before patching is recommended by the clinical guidelines of several countries. The aim of this study was to compare an intensive patching regimen, with and without extended optical treatment (EOT), in a randomised controlled trial.

METHODS

EuPatch was a randomised controlled trial conducted in 30 hospitals in the UK, Greece, Austria, Germany, and Switzerland. Children aged 3-8 years with newly detected, untreated amblyopia (defined as an interocular difference ≥0·30 logarithm of the minimum angle of resolution [logMAR] best corrected visual acuity [BCVA]) due to anisometropia, strabismus, or both were eligible. Participants were randomly assigned (1:1) via a computer-generated sequence to either the EOT group (18 weeks of glasses use before patching) or to the early patching group (3 weeks of glasses use before patching), stratified for type and severity of amblyopia. All participants were initially prescribed an intensive patching regimen (10 h/day, 6 days per week), supplemented with motivational materials. The patching period was up to 24 weeks. Participants, parents or guardians, assessors, and the trial statistician were not masked to treatment allocation. The primary outcome was successful treatment (ie, ≤0·20 logMAR interocular difference in BCVA) after 12 weeks of patching. Two primary analyses were conducted: the main analysis included all participants, including those who dropped out, but excluded those who did not provide outcome data at week 12 and remained on the study; the other analysis imputed this missing data. All eligible and randomly assigned participants were assessed for adverse events. This study is registered with the International Standard Randomised Controlled Trial Number registry (ISRCTN51712593) and is no longer recruiting.

FINDINGS

Between June 20, 2013, and March 12, 2020, after exclusion of eight participants found ineligible after detailed screening, we randomly assigned 334 participants (170 to the EOT group and 164 to the early patching group), including 188 (56%) boys, 146 (44%) girls, and two (1%) participants whose sex was not recorded. 317 participants (158 in the EOT group and 159 in the early patching group) were analysed for the primary outcome without imputation of missing data (median follow-up time 42 weeks [IQR 42] in the EOT group vs 27 weeks [27] in the early patching group). 24 (14%) of 170 participants in the EOT group and ten (6%) of 164 in the early patching group were excluded or dropped out of the study, mostly due to loss to follow-up and withdrawal of consent; ten (6%) in the EOT group and three (2%) in the early patching group missed the 12 week visit but remained on the study. A higher proportion of participants in the early patching group had successful treatment (107 [67%] of 159) than those in the EOT group (86 [54%] of 158; 13% difference; p=0·019) after 12 weeks of patching. No serious adverse events related to the interventions occurred.

INTERPRETATION

The results from this trial indicate that early patching is more effective than EOT for the treatment of most children with amblyopia. Our findings also provide data for the personalisation of amblyopia treatments.

FUNDING

Action Medical Research, NIHR Clinical Research Network, and Ulverscroft Foundation.

ERG Responses in Albinism, Idiopathic Infantile Nystagmus, and Controls

Purpose

Our primary aim was to compare adult full-field ERG (ffERG) responses in albinism, idiopathic infantile nystagmus (IIN), and controls. A secondary aim was to investigate the effect of within-subject changes in nystagmus eye movements on ffERG responses.

Methods

Dilated Ganzfeld flash ffERG responses were recorded using DTL electrodes under conditions of dark (standard and dim flash) and light adaptation in 68 participants with albinism, 43 with IIN, and 24 controls. For the primary aim, the effect of group and age on ffERG responses was investigated. For the secondary aim, null region characteristics were determined using eye movements recorded prior to ffERG recordings. ffERG responses were recorded near and away from the null regions of 18 participants also measuring the success rate of recordings.

Results

For the primary aim, age-adjusted photopic a- and b-wave amplitudes were consistently smaller in IIN compared with controls (P < 0.0001), with responses in both groups decreasing with age. In contrast, photopic a-wave amplitudes increased with age in albinism (P = 0.0035). For the secondary aim, more intense nystagmus significantly reduced the success rate of measurable responses. Within-subject changes in nystagmus intensity generated small, borderline significant differences in photopic b-wave peak times and a-and b-wave amplitudes under scotopic conditions with standard flash.

Conclusions

Age-adjusted photopic ffERG responses are significantly reduced in IIN adding to the growing body of evidence of retinal abnormalities in IIN. Differences between photopic responses in albinism and controls depend on age. Success at obtaining ffERG responses could be improved by recording responses at the null region.

USE OF HAND-HELD OPTICAL COHERENCE TOMOGRAPHY DURING RETINOPATHY OF PREMATURITY SCREENING DEMONSTRATES AN INCREASED OUTER RETINA FROM EARLY POSTMENSTRUAL AGE IN PRETERM INFANTS WITH RETINOPATHY OF PREMATURITY

PURPOSE

To identify structural markers of active retinopathy of prematurity (ROP) in foveal and parafoveal retinal layers using hand-held optical coherence tomography.

METHODS

Hand-held optical coherence tomography images (n = 278) were acquired from a prospective mixed cross-sectional longitudinal observational study of 87 participants (23-36 weeks gestational age; n = 30 with ROP, n = 57 without ROP) between 31 and 44 weeks postmenstrual age excluding treated ROP and features of cystoid macular edema. Six retinal layer thicknesses from the fovea to the parafovea were analyzed at five locations up to 1,000 µ m, temporally and nasally.

RESULTS

The mean outer retinal thickness during active ROP increased at the fovea and parafovea from postmenstrual age 33 weeks to 39 weeks ( P < 0.001), whereas the parafoveal inner nuclear layer and retinal nerve fiber layer reduced ( P < 0.001). Outer retinal thickness at the fovea from 33 weeks to 39 weeks postmenstrual age was consistently thicker in infants with ROP across all levels of prematurity (gestational age).

CONCLUSION

Increased foveal and parafoveal outer retina measured using hand-held optical coherence tomography shows potential as a marker for ROP screening.

Visual Field Deficits in Albinism in Comparison to Idiopathic Infantile Nystagmus

Purpose

This is the first systematic comparison of visual field (VF) deficits in people with albinism (PwA) and idiopathic infantile nystagmus (PwIIN) using static perimetry. We also compare best-corrected visual acuity (BCVA) and optical coherence tomography measures of the fovea, parafovea, and circumpapillary retinal nerve fiber layer in PwA.

Methods

VF testing was performed on 62 PwA and 36 PwIIN using a Humphrey Field Analyzer (SITA FAST 24-2). Mean detection thresholds for each eye were calculated, along with quadrants and central measures. Retinal layers were manually segmented in the macular region.

Results

Mean detection thresholds were significantly lower than normative values for PwA (-3.10 ± 1.67 dB, P << 0.0001) and PwIIN (-1.70 ± 1.54 dB, P < 0.0001). Mean detection thresholds were significantly lower in PwA compared to PwIIN (P < 0.0001) and significantly worse for left compared to right eyes in PwA (P = 0.0002) but not in PwIIN (P = 0.37). In PwA, the superior nasal VF was significantly worse than other quadrants (P < 0.05). PwIIN appeared to show a mild relative arcuate scotoma. In PwA, central detection thresholds were correlated with foveal changes in the inner and outer retina. VF was strongly correlated to BCVA in both groups.

Conclusions

Clear peripheral and central VF deficits exist in PwA and PwIIN, and static VF results need to be interpreted with caution clinically. Since PwA exhibit considerably lower detection thresholds compared to PwIIN, VF defects are unlikely to be due to nystagmus in PwA. In addition to horizontal VF asymmetry, PwA exhibit both vertical and interocular asymmetries, which needs further exploration.

Phenotypic Features Determining Visual Acuity in Albinism and the Role of Amblyogenic Factors

Albinism is a spectrum disorder causing foveal hypoplasia, nystagmus, and hypopigmentation of the iris and fundus along with other visual deficits, which can all impact vision. Albinism is also associated with amblyogenic factors which could affect monocular visual acuity. The foveal appearance in albinism can range from mild foveal hypoplasia to that which is indistinguishable from the peripheral retina. The appearance can be quickly and easily graded using the Leicester Grading System in the clinic. However, interquartile ranges of 0.3 logMAR for the grades associated with albinism limit the accuracy of the grading system in predicting vision. Here, we discuss the potential role of nystagmus presenting evidence that it may not be a major source of variability in the prediction of visual acuity. We also show that interocular differences in visual acuity are low in albinism despite high levels of amblyogenic factors indicating that active suppression of vision in one eye in albinism is uncommon.

Achromatopsia-Visual Cortex Stability and Plasticity in the Absence of Functional Cones

Purpose

Achromatopsia is a rare inherited disorder rendering retinal cone photoreceptors nonfunctional. As a consequence, the sizable foveal representation in the visual cortex is congenitally deprived of visual input, which prompts a fundamental question: is the cortical representation of the central visual field in patients with achromatopsia remapped to take up processing of paracentral inputs? Such remapping might interfere with gene therapeutic treatments aimed at restoring cone function.

Methods

We conducted a multicenter study to explore the nature and plasticity of vision in the absence of functional cones in a cohort of 17 individuals affected by autosomal recessive achromatopsia and confirmed biallelic disease-causing CNGA3 or CNGB3 mutations. Specifically, we tested the hypothesis of foveal remapping in human achromatopsia. For this purpose, we applied two independent functional magnetic resonance imaging (fMRI)-based mapping approaches, i.e. conventional phase-encoded eccentricity and population receptive field mapping, to separate data sets.

Results

Both fMRI approaches produced the same result in the group comparison of achromatopsia versus healthy controls: sizable remapping of the representation of the central visual field in the primary visual cortex was not apparent.

Conclusions

Remapping of the cortical representation of the central visual field is not a general feature in achromatopsia. It is concluded that plasticity of the human primary visual cortex is less pronounced than previously assumed. A pretherapeutic imaging workup is proposed to optimize interventions.

CHIASM-Net: Artificial Intelligence-Based Direct Identification of Chiasmal Abnormalities in Albinism

Purpose

Albinism is a congenital disorder affecting pigmentation levels, structure, and function of the visual system. The identification of anatomical changes typical for people with albinism (PWA), such as optic chiasm malformations, could become an important component of diagnostics. Here, we tested an application of convolutional neural networks (CNNs) for this purpose.

Methods

We established and evaluated a CNN, referred to as CHIASM-Net, for the detection of chiasmal malformations from anatomic magnetic resonance (MR) images of the brain. CHIASM-Net, composed of encoding and classification modules, was developed using MR images of controls (n = 1708) and PWA (n = 32). Evaluation involved 8-fold cross validation involving accuracy, precision, recall, and F1-score metrics and was performed on a subset of controls and PWA samples excluded from the training. In addition to quantitative metrics, we used Explainable AI (XAI) methods that granted insights into factors driving the predictions of CHIASM-Net.

Results

The results for the scenario indicated an accuracy of 85 ± 14%, precision of 90 ± 14% and recall of 81 ± 18%. XAI methods revealed that the predictions of CHIASM-Net are driven by optic-chiasm white matter and by the optic tracts.

Conclusions

CHIASM-Net was demonstrated to use relevant regions of the optic chiasm for albinism detection from magnetic resonance imaging (MRI) brain anatomies. This indicates the strong potential of CNN-based approaches for visual pathway analysis and ultimately diagnostics.

Severity of cystoid macular oedema in preterm infants observed using hand-held spectral domain optical coherence tomography improves weekly with postmenstrual age

OBJECTIVE

To investigate the relationship between cystoid macular oedema (CMO) measured in preterm infants using hand-held spectral domain optical coherence tomography (HH SD-OCT), with gestational age at birth (GA), birthweight (BW), diagnosis of retinopathy of prematurity (ROP) and the presence or absence of the external limiting membrane (ELM).

METHODS

We conducted a prospective mixed cross-sectional/longitudinal observational study of 112 participants (23 to 36 weeks GA; n = 25 with, and n = 87 without, CMO). Retinal images were acquired using 344 HH SD-OCT (n = 66 with and n = 278 without, CMO) between 31 to 44 weeks postmenstrual age (PMA). CMO type ('fovea' and 'dome') was measured using thickness, width, area and peak.

RESULTS

CMO was observed in 22.9% of preterm infants, and 19.2% of images. The mean values for  thickness, width, area and peak of 'dome' CMO were 128.47 µm (SD +/- 34.23), 3624.45 µm (SD +/- 1323.03), 0.49 mm2 (SD +/- 0.28) and 279.81 µm (SD +/- 13.57) respectively. The mean values for  thickness, width, area and peak of 'fovea' CMO were 64.37 µm (SD +/- 17.11), 2226.28 µm (SD +/- 1123.82), 0.16 mm2 (SD +/- 0.11) and 95.03 µm (SD +/- 26.99) respectively. Thickness, area width and peak were significantly greater for 'dome CMO compared with 'fovea' CMO (P < 0.0001 for thickness, area and peak; P < 0.01 for width). Area and width significantly decreased with PMA for 'dome' and 'fovea' CMO (p = 0.0028; p < 0.001 respectively). No association was found between the presence of ROP and the detection of CMO or detection of CMO with absence of ELM.

CONCLUSIONS

HH -OCT in preterm infants demonstrates that the severity of CMO appearance improves each week for both fovea and dome CMO.

First-in-Human Gene Therapy Trial of AAV8-hCARp.hCNGB3 in Adults and Children With CNGB3-associated Achromatopsia

PURPOSE

To assess the safety and efficacy of AAV8-hCARp.hCNGB3 in participants with CNGB3-associated achromatopsia (ACHM).

DESIGN

Prospective, phase 1/2 (NCT03001310), open-label, nonrandomized clinical trial.

METHODS

The study enrolled 23 adults and children with CNGB3-associated ACHM. In the dose-escalation phase, adult participants were administered 1 of 3 AAV8-hCARp.hCNGB3 dose levels in the worse-seeing eye (up to 0.5 mL). After a maximum tolerated dose was established in adults, an expansion phase was conducted in children ≥3 years old. All participants received topical and oral corticosteroids. Safety and efficacy parameters, including treatment-related adverse events and visual acuity, retinal sensitivity, color vision, and light sensitivity, were assessed for 6 months.

RESULTS

AAV8-hCARp.hCNGB3 (11 adults, 12 children) was safe and generally well tolerated. Intraocular inflammation occurred in 9 of 23 participants and was mainly mild or moderate in severity. Severe cases occurred primarily at the highest dose. Two events were considered serious and dose limiting. All intraocular inflammation resolved following topical and systemic steroids. There was no consistent pattern of change from baseline to week 24 for any efficacy assessment. However, favorable changes were observed for individual participants across several assessments, including color vision (n = 6/23), photoaversion (n = 11/20), and vision-related quality-of-life questionnaires (n = 21/23).

CONCLUSIONS

AAV8-hCARp.hCNGB3 for CNGB3-associated ACHM demonstrated an acceptable safety and tolerability profile. Improvements in several efficacy parameters indicate that AAV8-hCARp.hCNGB3 gene therapy may provide benefit. These findings, with the development of additional sensitive and quantitative end points, support continued investigation.

Clinical features and imaging characteristics in achiasmia

Achiasmia is a rare visual pathway maldevelopment with reduced decussation of the axons in the optic chiasm. Our aim was to investigate clinical characteristics, macular, optic nerve and brain morphology in achiasmia. A prospective, cross-sectional, observational study of 12 participants with achiasmia [8 males and 4 females; 29.6 ± 18.4 years (mean ± standard deviation)] and 24 gender-, age-, ethnicity- and refraction-matched healthy controls was done. Full ophthalmology assessment, eye movement recording, a high-resolution spectral-domain optical coherence tomography of the macular and optic disc, five-channel visual-evoked responses, eye movement recordings and MRI scans of the brain and orbits were acquired. Achiasmia was confirmed in all 12 clinical participants by visual-evoked responses. Visual acuity in this group was 0.63 ± 0.19 and 0.53 ± 0.19 for the right and left eyes, respectively; most participants had mild refractive errors. All participants with achiasmia had see-saw nystagmus and no measurable stereo vision. Strabismus and abnormal head position were noted in 58% of participants. Optical coherence tomography showed optic nerve hypoplasia with associated foveal hypoplasia in four participants. In the remaining achiasmia participants, macular changes with significantly thinner paracentral inner segment (P = 0.002), wider pit (P = 0.04) and visual flattening of the ellipsoid line were found. MRI demonstrated chiasmatic aplasia in 3/12 (25%), chiasmatic hypoplasia in 7/12 (58%) and a subjectively normal chiasm in 2/12 (17%). Septo-optic dysplasia and severe bilateral optic nerve hypoplasia were found in three patients with chiasmic aplasia/hypoplasia on MRI. In this largest series of achiasmia patients to date, we found for the first time that neuronal abnormalities occur already at the retinal level. Foveal changes, optic nerve hypoplasia and the midline brain anomaly suggest that these abnormalities could be part of the same spectrum, with different manifestations of events during foetal development occurring with varying severity.

Abnormal foveal morphology in carriers of oculocutaneous albinism

BACKGROUND/AIMS

To investigate the foveal morphology in carriers of oculocutaneous albinism (OCA) using spectral domain optical coherence tomography (SD-OCT). A cross-sectional, observational study.

METHODS

Handheld SD-OCT (Envisu C2300) was used to acquire horizontal scans through the centre of the fovea in biological parents of patients with OCA (n=28; mean age±SD=40.43±8.07 years) and age-matched and ethnicity-matched controls (n=28; mean age±SD=38.04±10.27 years). Sequence analysis was performed for variants in known genes associated with OCA. Best-corrected visual acuity (BCVA), presence of foveal hypoplasia and grade, foveal, parafoveal and perifoveal thickness measurements of total retinal layers (TRL), inner retinal layers (IRL) and outer retinal layers (ORL) thickness were measured.

RESULTS

Foveal hypoplasia was identified in 32.14% of OCA carriers; grade 1 in all cases. OCA carriers demonstrated significant thicker TRL thickness (median difference: 13.46 µm, p=0.009) and IRL thickness (mean difference: 8.98 µm, p<0.001) at the central fovea compared with controls. BCVA of carriers was between -0.16 and 0.18 logMAR (mean: 0.0 logMAR). No significant differences in BCVA was noted between OCA carriers or controls (p=0.83). In the OCA carriers, we identified previously reported pathogenic variants in TYR, OCA2 and SLC45A2, novel OCA2 variants (n=3) and heterozygosity of the pathogenic TYR haplotype.

CONCLUSION

We have, for the first time, identified foveal abnormalities in OCA carriers. This provides clinical value, particularly in cases where limited phenotype data are available. Our findings raise the possibility that previously reported mild cases of foveal hypoplasia or isolated foveal hypoplasia could correspond to OCA carrier status.

Predicting Acute and Post-Recovery Outcomes in Cerebral Malaria and Other Comas by Optical Coherence Tomography (OCT in CM) - A protocol for an observational cohort study of Malawian children

Cerebral malaria (CM) remains a significant global health challenge with high morbidity and mortality. Malarial retinopathy has been shown to be diagnostically and prognostically significant in the assessment of CM. The major mechanism of death in paediatric CM is brain swelling. Long term morbidity is typically characterised by neurological and neurodevelopmental sequelae. Optical coherence tomography can be used to quantify papilloedema and macular ischaemia, identified as hyperreflectivity. Here we describe a protocol to test the hypotheses that quantification of optic nerve head swelling using optical coherence tomography can identify severe brain swelling in CM, and that quantification of hyperreflectivity in the macula predicts neurodevelopmental outcomes post-recovery. Additionally, our protocol includes the development of a novel, low-cost, handheld optical coherence tomography machine and artificial intelligence tools to assist in image analysis.

Eye movement defects in KO zebrafish reveals SRPK3 as a causative gene for an X-linked intellectual disability

Intellectual disability (ID) is a common neurodevelopmental disorder characterized by significantly impaired intellectual and adaptive functioning. X-linked ID (XLID) disorders, caused by defects in genes on the X chromosome, affect 1.7 out of 1,000 males. Employing exome sequencing, we identified three missense mutations (c.475C>G; p.H159D, c.1373C>A; p.T458N, and c.1585G>A; p.E529K) in the SRPK3 gene in seven XLID patients from three independent families. Clinical features common to the patients are intellectual disability, agenesis of the corpus callosum, abnormal smooth pursuit eye movement, and ataxia. SRPK proteins are known to be involved in mRNA processing and, recently, synaptic vesicle and neurotransmitter release. In order to validate SRPK3 as a novel XLID gene, we established a knockout (KO) model of the SRPK3 orthologue in zebrafish. In day 5 of larval stage, KO zebrafish showed significant defects in spontaneous eye movement and swim bladder inflation. In adult KO zebrafish, we found agenesis of cerebellar structures and impairments in social interaction. These results suggest an important role of SRPK3 in eye movements, which might reflect learning problems, intellectual disability, and other psychiatric disorders.

Retinal Development in Infants and Young Children With Albinism: Evidence for Plasticity in Early Childhood

MEETING PRESENTATION

Presented at the 2016 Association for Research in Vision and Ophthalmology meeting and at the 2015 British Isles Paediatric, Ophthalmology and Strabismus Association meeting.

PURPOSE

To investigate the time course of foveal development after birth in infants with albinism.

DESIGN

Prospective, comparative cohort optical coherence tomography study.

METHODS

Thirty-six children with albinism were recruited. All participants were between 0 and 6 years of age and were seen at Leicester Royal Infirmary. A total of 181 mixed cross-sectional and longitudinal optical coherence tomography examinations were obtained, which were analyzed for differences in retinal development in comparison to 297 cross-sectional control examinations.

RESULTS

Normal retinal development involves migration of the inner retinal layers (IRLs) away from the fovea, migration of the cone photoreceptors into the fovea, and elongation of the outer retinal layers (ORLs) over time. In contrast to controls where IRL migration from the fovea was almost completed at birth, a significant degree of IRL migration was taking place after birth in albinism, before arresting prematurely at 40 months postmenstrual age (PMA). This resulted in a significantly thicker central macular thickness in albinism (Δ = 83.8 ± 6.1, P < .0001 at 69 months PMA). There was evidence of ongoing foveal ORL elongation in albinism, although reduced in amplitude compared with control subjects after 21 months PMA (Δ = -17.3 ± 4.3, P < .0001).

CONCLUSIONS

We have demonstrated evidence of ongoing retinal development in young children with albinism, albeit at a reduced rate and magnitude compared with control subjects. The presence of a period of retinal plasticity in early childhood raises the possibility that treatment modalities, which aim to improve retinal development, could potentially optimize visual function in albinism.

Electrophysiological and fundoscopic detection of intracranial hypertension in craniosynostosis

AIMS

To assess the diagnostic accuracy of fundoscopy and visual evoked potentials (VEPs) in detecting intracranial hypertension (IH) in patients with craniosynostosis undergoing spring-assisted posterior vault expansion (sPVE).

METHODS

Children with craniosynostosis undergoing sPVE and 48-hour intracranial pressure (ICP) monitoring were included in this single-centre, retrospective, diagnostic accuracy study. Data for ICP, fundoscopy and VEPs were analysed. Primary outcome measures were papilloedema on fundoscopy, VEP assessments and IH, defined as mean ICP > 20 mmHg. Diagnostic indices were calculated for fundoscopy and VEPs against IH. Secondary outcome measures included final visual outcomes.

RESULTS

Fundoscopic examinations were available for 35 children and isolated VEPs for 30 children, 22 of whom had at least three serial VEPs. Sensitivity was 32.1% for fundoscopy (95% confidence intervals [CI]: 15.9-52.4) and 58.3% for isolated VEPs (95% CI 36.6-77.9). Specificity for IH was 100% for fundoscopy (95% CI: 59.0-100) and 83.3% for isolated VEPs (95% CI: 35.9-99.6). Where longitudinal deterioration was suspected from some prVEPs but not corroborated by all, sensitivity increased to 70.6% (95% CI: 44.0-89.7), while specificity decreased to 60% (95% CI: 14.7-94.7). Where longitudinal deterioration was clinically significant, sensitivity decreased to 47.1% (23.0-72.2) and specificity increased to 100% (47.8-100). Median final BCVA was 0.24 logMAR (n = 36). UK driving standard BCVA was achieved by 26 patients (72.2%), defined as ≥0.30 logMAR in the better eye.

CONCLUSION

Papilloedema present on fundoscopy reliably indicated IH, but its absence did not exclude IH. VEP testing boosted sensitivity at the expense of specificity, depending on method of analysis.

Longitudinal Evaluation of Changes in Retinal Architecture Using Optical Coherence Tomography in Achromatopsia

Purpose

This prospective study investigates longitudinal changes in retinal structure in patients with achromatopsia (ACHM) using optical coherence tomography (OCT).

Methods

Seventeen patients (five adults, 12 children) with genetically confirmed CNGA3- or CNGB3-associated ACHM underwent ocular examination and OCT over a follow-up period of between 2 and 9.33 years (mean = 5.7 years). Foveal tomograms were qualitatively graded and were segmented for quantitative analysis: central macular thickness (CMt), outer nuclear layer thickness (ONLt), and size of the foveal hyporeflective zone (vertical HRZ thickness: HRZt and horizontal HRZ width: HRZw) were measured. Data were analyzed using linear mixed regression models. Both age and visit were included into the models, to explore the possibility that the rate of disease progression depends on patient age.

Results

Fifteen of 17 patients (88%) showed longitudinal changes in retinal structure over the follow-up period. The most common patterns of progression was development of ellipsoid zone (EZ) disruption and HRZ. There was a significant increase in HRZt (P = 0.01) and HRZw (P = 0.001) between visits and no significant change in CMt and ONLt. Retinal parameters showed no difference in changes by genetic mutation (CNGA3 (n = 11), CNGB3 (n = 6)).

Conclusions

This study demonstrates clear longitudinal changes in foveal structure mainly in children, but also in adults with ACHM, over a long follow-up period. The longitudinal foveal changes suggest that treatment at an earlier age should be favored.

Short-term progression of optic disc and macular changes in optic nerve head drusen

PURPOSE

To quantify in patients with optic nerve head drusen (ONHD)changes after 1-year observation in: (i) optic disc and (ii) macular optical coherence tomography (OCT) parameters and (iii) the effect of age at enrolment in the study.

DESIGN

Prospective, cross-sectional observational study using Spectral Domain-OCT (Copernicus; OPTOPOL Technology S.A., Zawiercie, Poland) imaging was carried out in 35 patients with ONHD (age-42.8 ± 19.9 years; males = 15; females = 20) at baseline and after 12 months follow-up.

RESULTS

Patients with ONHD had significant thinning of the surface nerve fibre layer in the central (p = 0.03), superior (p = 0.05) and inferior (p = 0.04) areas; mean ppRNFL thinning (p = 0.0 4) and ppRNFL thinning in the nasal segment (p = 0.028). Retinal thinning in the central (p = 0.001), inner (p = 0.01) and outer (p = 0.002) temporal, outer superior (p = 0.03) and inferior (p = 0.02) areas; borderline ganglion cell layer thinning (p = 0.051) and outer nuclear layer (p = 0.03) thinning in the central retina and outer segment layer thinning nasally (p = 0.01) between the first and the second visit in macula. Correlation of the difference in optic disc and macular parameters with the age at enrolment did not reveal any significance.

CONCLUSIONS

Statistically detectable thinning of the optic nerve and macula structures occurred already after 12 months. The proximity of optic nerve changes to the vascular arcades can possibly be explained by involvement of retinal vessels in the pathophysiology of ONHD.

Comprehensive variant spectrum of the CNGA3 gene in patients affected by achromatopsia

Achromatopsia (ACHM) is a congenital cone photoreceptor disorder characterized by impaired color discrimination, low visual acuity, photosensitivity, and nystagmus. To date, six genes have been associated with ACHM (CNGA3, CNGB3, GNAT2, PDE6C, PDE6H, and ATF6), the majority of these being implicated in the cone phototransduction cascade. CNGA3 encodes the CNGA3 subunit of the cyclic nucleotide-gated ion channel in cone photoreceptors and is one of the major disease-associated genes for ACHM. Herein, we provide a comprehensive overview of the CNGA3 variant spectrum in a cohort of 1060 genetically confirmed ACHM patients, 385 (36.3%) of these carrying "likely disease-causing" variants in CNGA3. Compiling our own genetic data with those reported in the literature and in public databases, we further extend the CNGA3 variant spectrum to a total of 316 variants, 244 of which we interpreted as "likely disease-causing" according to ACMG/AMP criteria. We report 48 novel "likely disease-causing" variants, 24 of which are missense substitutions underlining the predominant role of this mutation class in the CNGA3 variant spectrum. In addition, we provide extensive in silico analyses and summarize reported functional data of previously analyzed missense, nonsense and splicing variants to further advance the pathogenicity assessment of the identified variants.

Genotypic and Phenotypic Spectrum of Foveal Hypoplasia: A Multicenter Study

PURPOSE

To characterize the genotypic and phenotypic spectrum of foveal hypoplasia (FH).

DESIGN

Multicenter, observational study.

PARTICIPANTS

A total of 907 patients with a confirmed molecular diagnosis of albinism, PAX6, SLC38A8, FRMD7, AHR, or achromatopsia from 12 centers in 9 countries (n = 523) or extracted from publicly available datasets from previously reported literature (n = 384).

METHODS

Individuals with a confirmed molecular diagnosis and availability of foveal OCT scans were identified from 12 centers or from the literature between January 2011 and March 2021. A genetic diagnosis was confirmed by sequence analysis. Grading of FH was derived from OCT scans.

MAIN OUTCOME MEASURES

Grade of FH, presence or absence of photoreceptor specialization (PRS+ vs. PRS-), molecular diagnosis, and visual acuity (VA).

RESULTS

The most common genetic etiology for typical FH in our cohort was albinism (67.5%), followed by PAX6 (21.8%), SLC38A8 (6.8%), and FRMD7 (3.5%) variants. AHR variants were rare (0.4%). Atypical FH was seen in 67.4% of achromatopsia cases. Atypical FH in achromatopsia had significantly worse VA than typical FH (P < 0.0001). There was a significant difference in the spectrum of FH grades based on the molecular diagnosis (chi-square = 60.4, P < 0.0001). All SLC38A8 cases were PRS- (P = 0.003), whereas all FRMD7 cases were PRS+ (P < 0.0001). Analysis of albinism subtypes revealed a significant difference in the grade of FH (chi-square = 31.4, P < 0.0001) and VA (P = 0.0003) between oculocutaneous albinism (OCA) compared with ocular albinism (OA) and Hermansky-Pudlak syndrome (HPS). Ocular albinism and HPS demonstrated higher grades of FH and worse VA than OCA. There was a significant difference (P < 0.0001) in VA between FRMD7 variants compared with other diagnoses associated with FH.

CONCLUSIONS

We characterized the phenotypic and genotypic spectrum of FH. Atypical FH is associated with a worse prognosis than all other forms of FH. In typical FH, our data suggest that arrested retinal development occurs earlier in SLC38A8, OA, HPS, and AHR variants and later in FRMD7 variants. The defined time period of foveal developmental arrest for OCA and PAX6 variants seems to demonstrate more variability. Our findings provide mechanistic insight into disorders associated with FH and have significant prognostic and diagnostic value.

Abnormal Retinal Vessel Architecture in Albinism and Idiopathic Infantile Nystagmus

Purpose

Infantile nystagmus syndrome (INS) causes altered visual development and can be associated with abnormal retinal structure, to which vascular development of the retina is closely related. Abnormal retinal vasculature has previously been noted in albinism but not idiopathic infantile nystagmus. We compared the number and diameter of retinal vessels in participants with albinism (PWA) and idiopathic infantile nystagmus (PWIIN) with controls.

Methods

Fundus photography data from 24 PWA, 10 PWIIN, and 34 controls was analyzed using Automated Retinal Image Analyzer (ARIA) software on a field of analysis centered on the optic disc, the annulus of which extended between 4.2 mm and 8.4 mm in diameter.

Results

Compared with controls, the mean number of arterial branches was reduced by 24% in PWA (15.5 vs. 20.3, P < 0.001), and venous branches were reduced in both PWA (29%; 12.9 vs. 18.2, P < 0.001) and PWIIN (17%; 15.1 vs. 18.2, P = 0.024). PWA demonstrated 7% thinner "primary" (before branching) arteries (mean diameter: 75.39 µm vs. 80.88 µm, P = 0.043), and 13% thicker (after branching) "secondary" veins (66.72 µm vs. 59.01 µm in controls, P = 0.009).

Conclusions

PWA and PWIIN demonstrated reduced retinal vessel counts and arterial diameters compared with controls. These changes in the superficial retinal vascular network may be secondary to underdevelopment of the neuronal network, which guides vascular development and is also known to be disrupted in INS.

Normal and abnormal foveal development

Normal foveal development begins in utero at midgestation with centrifugal displacement of inner retinal layers (IRLs) from the location of the incipient fovea. The outer retinal changes such as increase in cone cell bodies, cone elongation and packing mainly occur after birth and continue until 13 years of age. The maturity of the fovea can be assessed invivo using optical coherence tomography, which in normal development would show a well-developed foveal pit, extrusion of IRLs, thickened outer nuclear layer and long outer segments. Developmental abnormalities of various degrees can result in foveal hypoplasia (FH). This is a characteristic feature for example in albinism, aniridia, prematurity, foveal hypoplasia with optic nerve decussation defects with or without anterior segment dysgenesis without albinism (FHONDA) and optic nerve hypoplasia. In achromatopsia, there is disruption of the outer retinal layers with atypical FH. Similarly, in retinal dystrophies, there is abnormal lamination of the IRLs sometimes with persistent IRLs. Morphology of FH provides clues to diagnoses, and grading correlates to visual acuity. The outer segment thickness is a surrogate marker for cone density and in foveal hypoplasia this correlates strongly with visual acuity. In preverbal children grading FH can help predict future visual acuity.

Structural changes to primary visual cortex in the congenital absence of cone input in achromatopsia

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Anatomy of primary visual cortex (V1) assessed with surface-based morphmetry in those with congenital achromatopsia (ACHM).

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Reduction in cortical surface area in foveal, parafoveal and paracentral representations of V1 in those with ACHM.

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In ACHM a localized thickening in the area of V1 that represents the region of retina occupied solely by cones.

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V1 changes in ACHM may limit its ability to take on normal properties if retinal function were to be restored.

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Early intervention, before the development plastic period is over, may offer better restoration of vision in ACHM.

Autosomal recessive Achromatopsia (ACHM) is a rare inherited disorder associated with dysfunctional cone photoreceptors resulting in a congenital absence of cone input to visual cortex. This might lead to distinct changes in cortical architecture with a negative impact on the success of gene augmentation therapies. To investigate the status of the visual cortex in these patients, we performed a multi-centre study focusing on the cortical structure of regions that normally receive predominantly cone input. Using high-resolution T1-weighted MRI scans and surface-based morphometry, we compared cortical thickness, surface area and grey matter volume in foveal, parafoveal and paracentral representations of primary visual cortex in 15 individuals with ACHM and 42 normally sighted, healthy controls (HC). In ACHM, surface area was reduced in all tested representations, while thickening of the cortex was found highly localized to the most central representation. These results were comparable to more widespread changes in brain structure reported in congenitally blind individuals, suggesting similar developmental processes, i.e., irrespective of the underlying cause and extent of vision loss. The cortical differences we report here could limit the success of treatment of ACHM in adulthood. Interventions earlier in life when cortical structure is not different from normal would likely offer better visual outcomes for those with ACHM.

Recognition of intracranial hypertension using handheld optical coherence tomography in children (RIO Study): a diagnostic accuracy study protocol

INTRODUCTION

Paediatric intracranial hypertension (IH) is a rare but serious condition that can pose deleterious effects on the brain and vision. Estimating intracranial pressure (ICP) in children is difficult. Gold standard direct ICP measurement is invasive and carries risk. It is impractical to routinely perform direct ICP measurements over time for all children at risk of IH. This study proposes to assess the diagnostic accuracy of handheld optical coherence tomography (OCT), a non-invasive ocular imaging method, to detect IH in children.

METHODS AND ANALYSIS

This is a prospective study evaluating the diagnostic accuracy of handheld OCT for IH in at risk children. Inclusion criteria include clinical and/or genetic diagnosis of craniosynostosis, idiopathic intracranial hypertension, space occupying lesion or other conditions association with IH and age 0-18 years old. Exclusion criteria include patients older than 18 years of age and/or absence of condition placing the child at risk of IH. The primary outcome measures are handheld OCT and 48-hour ICP assessments, which will be used for diagnostic accuracy testing (sensitivity, specificity, positive predictive value, negative predictive value and accuracy). Main secondary outcome measures include visual acuity, fundoscopic examination, contrast sensitivity, visual field testing and visual evoked potentials, wherever possible.

ETHICS AND DISSEMINATION

Ethical approval was granted for this study by the East Midlands Nottingham 2 Research Ethics committee (UOL0348/IRAS 105137). Our findings will be disseminated through presentation at relevant meetings, peer-reviewed publication and via the popular media.

TRIAL REGISTRATION NUMBER

ISRCTN52858719.

Structural Differences Across Multiple Visual Cortical Regions in the Absence of Cone Function in Congenital Achromatopsia

Most individuals with congenital achromatopsia (ACHM) carry mutations that affect the retinal phototransduction pathway of cone photoreceptors, fundamental to both high acuity vision and colour perception. As the central fovea is occupied solely by cones, achromats have an absence of retinal input to the visual cortex and a small central area of blindness. Additionally, those with complete ACHM have no colour perception, and colour processing regions of the ventral cortex also lack typical chromatic signals from the cones. This study examined the cortical morphology (grey matter volume, cortical thickness, and cortical surface area) of multiple visual cortical regions in ACHM (n = 15) compared to normally sighted controls (n = 42) to determine the cortical changes that are associated with the retinal characteristics of ACHM. Surface-based morphometry was applied to T1-weighted MRI in atlas-defined early, ventral and dorsal visual regions of interest. Reduced grey matter volume in V1, V2, V3, and V4 was found in ACHM compared to controls, driven by a reduction in cortical surface area as there was no significant reduction in cortical thickness. Cortical surface area (but not thickness) was reduced in a wide range of areas (V1, V2, V3, TO1, V4, and LO1). Reduction in early visual areas with large foveal representations (V1, V2, and V3) suggests that the lack of foveal input to the visual cortex was a major driving factor in morphological changes in ACHM. However, the significant reduction in ventral area V4 coupled with the lack of difference in dorsal areas V3a and V3b suggest that deprivation of chromatic signals to visual cortex in ACHM may also contribute to changes in cortical morphology. This research shows that the congenital lack of cone input to the visual cortex can lead to widespread structural changes across multiple visual areas.

Cerebral malaria: insight into pathology from optical coherence tomography

We aimed to investigate structural retinal changes in malarial retinopathy (MR) using hand-held optical coherence tomography (HH-OCT) to assess its diagnostic potential. Children with MR (n = 43) underwent ophthalmoscopy, fluorescein angiography and HH-OCT during admission, 1-month (n = 31) and 1-year (n = 8) post-discharge. Controls were comatose patients without malaria (n = 6) and age/sex-matched healthy children (n = 43). OCT changes and retinal layer thicknesses were compared. On HH-OCT, hyper-reflective areas (HRAs) were seen in the inner retina of 81% of MR patients, corresponding to ischaemic retinal whitening on fundus photography. Cotton wool spots were present in 37% and abnormal hyper-reflective dots, co-localized to capillary plexus, in 93%. Hyper-reflective vessel walls were present in 84%, and intra-retinal cysts in 9%. Vascular changes and cysts resolved within 48 h. HRAs developed into retinal thinning at 1 month (p = 0.027) which was more pronounced after 1 year (p = 0.009). Ischaemic retinal whitening is located within inner retinal layers, distinguishing it from cotton wool spots. Vascular hyper-reflectivity may represent the sequestration of parasitized erythrocytes in vessels, a key CM feature. The mechanisms of post-ischemic retinal atrophy and cerebral atrophy with cognitive impairment may be similar in CM survivors. HH-OCT has the potential for monitoring patients, treatment response and predicting neurological deficits.

Feasibility and Repeatability of Handheld Optical Coherence Tomography in Children With Craniosynostosis

Purpose

To determine whether handheld optical coherence tomography (OCT) is feasible and repeatable in children with craniosynostosis.

Methods

This was a prospective cross-sectional study. Children with syndromic and non-syndromic craniosynostosis 0 to 18 years of age were recruited between February 13, 2020, and October 1, 2020. Main outcome measures included feasibility (patient recruitment and handheld OCT success rates) and repeatability, which were assessed using intraclass correlation coefficients (ICCs) where repeated images of the optic nerve head (ONH) within the same visit were available. ONH parameters used for repeatability analysis included cup depth, width, and area; disc width; rim height; retinal thickness; retinal nerve fiber layer thickness; and Bruch's membrane opening minimum rim width.

Results

Fifty children were approached, and all 50 (100%) were successfully recruited. Median age was 51.1 months (range, 1.9-156.9; interquartile range, 37.0-74.2), and 33 of the children (66%) were male. At least one ONH image was obtained in 43 children (86%), and bilateral ONH imaging was successful in 38 children (76%). Factors boosting the likelihood of success included good understanding and cooperation of the child and parent/guardian and availability of an assistant. Repeatability analysis was performed in 20 children, demonstrating good repeatability (ICC range, 0.77-0.99; the majority exceeded 0.90). OCT correctly identified two cases of intracranial hypertension, one of which was undetected by prior fundoscopy.

Conclusions

Handheld OCT is feasible and repeatable in children with syndromic and non-syndromic forms of craniosynostosis.

Translational Relevance

Our handheld OCT approach could be used for the clinical surveillance of children with craniosynostosis.

Handheld Optical Coherence Tomography in a Young Infant With Albinism and Fovea Plana

ABSTRACT

We present handheld optical coherence tomography (OCT) diagnosis of Grade 4 foveal hypoplasia (fovea plana) in a 28-day-old infant with albinism. Grade 4 foveal hypoplasia is characterized by the absence of the foveal pit, absence of outer segment lengthening, and absence of outer nuclear layer widening. Binocular visual acuity at 58 months follow-up was 1.2 logarithm of the minimal angle of resolution (logMAR). We describe our handheld OCT acquisition protocol and compare the morphological features with a healthy, age-matched control subject.

Anterior Chamber Measurements in Healthy Children: A Cross-Sectional Study Using Optical Coherence Tomography

Purpose

To establish anterior chamber measurements in children and investigate the influence of demographic factors on anterior chamber development.

Methods

Handheld optical coherence tomography was used to scan the anterior chamber of participants' eyes, without sedation. ImageJ was used to generate quantitative anterior chamber measurements, including central corneal thickness (CCT), anterior chamber width, trabecular meshwork length (TML), Schwalbe's line-angle opening distance (SL-AOD), and trabecular iris surface area (SL-TISA). The average anterior chamber measurements per age group, with 95% prediction intervals, were estimated using fractional polynomial modeling. Mixed regression models were used to evaluate the influence of age, gender, eye, angle, and refractive error variation on anterior chamber measurements.

Results

Scans from 223 healthy children (2 days to 15 years of age) and 59 adults (16 to 47 years of age) were included. The anterior chamber width, TML, Schwalbe's line-angle opening distance, and Schwalbe's line-trabecular iris surface area significantly increased, whereas CCT decreased with aging (all P < 0.001). The anterior chamber has a rapid phase of development during the first 18 months of age and reaches maturity by the age of 5 years. Girls have significantly smaller anterior chambers compared with boys (all P < 0.001). There was no difference between right and left eye development (all P > 0.05). The temporal TML development was significantly greater than the nasal TML (P < 0.05). CCT development was negatively correlated with refractive power.

Conclusions

This novel, non-invasive study describes the postnatal development of anterior chamber in newborn children.

Translational Relevance

Our established quantitative measurements have potential clinical use in understanding anterior segment diseases.

Optic Nerve Head and Retinal Abnormalities Associated with Congenital Fibrosis of the Extraocular Muscles

Congenital fibrosis of the extraocular muscles (CFEOM) is a congenital cranial dysinnervation disorder caused by developmental abnormalities affecting cranial nerves/nuclei innervating the extraocular muscles. Autosomal dominant CFEOM arises from heterozygous missense mutations of KIF21A or TUBB3. Although spatiotemporal expression studies have shown KIF21A and TUBB3 expression in developing retinal ganglion cells, it is unclear whether dysinnervation extends beyond the oculomotor system. We aimed to investigate whether dysinnervation extends to the visual system by performing high-resolution optical coherence tomography (OCT) scans characterizing retinal ganglion cells within the optic nerve head and retina. Sixteen patients with CFEOM were screened for mutations in KIF21A, TUBB3, and TUBB2B. Six patients had apparent optic nerve hypoplasia. OCT showed neuro-retinal rim loss. Disc diameter, rim width, rim area, and peripapillary nerve fiber layer thickness were significantly reduced in CFEOM patients compared to controls (p < 0.005). Situs inversus of retinal vessels was seen in five patients. Our study provides evidence of structural optic nerve and retinal changes in CFEOM. We show for the first time that there are widespread retinal changes beyond the retinal ganglion cells in patients with CFEOM. This study shows that the phenotype in CFEOM extends beyond the motor nerves.

Recurrent Rare Copy Number Variants Increase Risk for Esotropia

Purpose

To determine whether rare copy number variants (CNVs) increase risk for comitant esotropia.

Methods

CNVs were identified in 1614 Caucasian individuals with comitant esotropia and 3922 Caucasian controls from Illumina SNP genotyping using two Hidden Markov model (HMM) algorithms, PennCNV and QuantiSNP, which call CNVs based on logR ratio and B allele frequency. Deletions and duplications greater than 10 kb were included. Common CNVs were excluded. Association testing was performed with 1 million permutations in PLINK. Significant CNVs were confirmed with digital droplet polymerase chain reaction (ddPCR). Whole genome sequencing was performed to determine insertion location and breakpoints.

Results

Esotropia patients have similar rates and proportions of CNVs compared with controls but greater total length and average size of both deletions and duplications. Three recurrent rare duplications significantly (P = 1 × 10⁻⁶) increase the risk of esotropia: chromosome 2p11.2 (hg19, 2:87428677-87965359), spanning one long noncoding RNA (lncRNA) and two microRNAs (OR 14.16; 95% confidence interval [CI] 5.4–38.1); chromosome 4p15.2 (hg19, 4:25554332-25577184), spanning one lncRNA (OR 11.1; 95% CI 4.6–25.2); chromosome 10q11.22 (hg19, 10:47049547-47703870) spanning seven protein-coding genes, one lncRNA, and four pseudogenes (OR 8.96; 95% CI 5.4–14.9). Overall, 114 cases (7%) and only 28 controls (0.7%) had one of the three rare duplications. No case nor control had more than one of these three duplications.

Conclusions

Rare CNVs are a source of genetic variation that contribute to the genetic risk for comitant esotropia, which is likely polygenic. Future research into the functional consequences of these recurrent duplications may shed light on the pathophysiology of esotropia.

SLC38A8 mutations result in arrested retinal development with loss of cone photoreceptor specialization

Foveal hypoplasia, optic nerve decussation defects and anterior segment dysgenesis is an autosomal recessive disorder arising from SLC38A8 mutations. SLC38A8 is a putative glutamine transporter with strong expression within the photoreceptor layer in the retina. Previous studies have been limited due to lack of quantitative data on retinal development and nystagmus characteristics. In this multi-centre study, a custom-targeted next generation sequencing (NGS) gene panel was used to identify SLC38A8 mutations from a cohort of 511 nystagmus patients. We report 16 novel SLC38A8 mutations. The sixth transmembrane domain is most frequently disrupted by missense SLC38A8 mutations. Ninety percent of our cases were initially misdiagnosed as PAX6-related phenotype or ocular albinism prior to NGS. We characterized the retinal development in vivo in patients with SLC38A8 mutations using high-resolution optical coherence tomography. All patients had severe grades of arrested retinal development with lack of a foveal pit and no cone photoreceptor outer segment lengthening. Loss of foveal specialization features such as outer segment lengthening implies reduced foveal cone density, which contributes to reduced visual acuity. Unlike other disorders (such as albinism or PAX6 mutations) which exhibit a spectrum of foveal hypoplasia, SLC38A8 mutations have arrest of retinal development at an earlier stage resulting in a more under-developed retina and severe phenotype.

Management of nystagmus in children: a review of the literature and current practice in UK specialist services

Nystagmus is an eye movement disorder characterised by abnormal, involuntary rhythmic oscillations of one or both eyes, initiated by a slow phase. It is not uncommon in the UK and regularly seen in paediatric ophthalmology and adult general/strabismus clinics. In some cases, it occurs in isolation, and in others, it occurs as part of a multisystem disorder, severe visual impairment or neurological disorder. Similarly, in some cases, visual acuity can be normal and in others can be severely degraded. Furthermore, the impact on vision goes well beyond static acuity alone, is rarely measured and may vary on a minute-to-minute, day-to-day or month-to-month basis. For these reasons, management of children with nystagmus in the UK is varied, and patients report hugely different experiences and investigations. In this review, we hope to shine a light on the current management of children with nystagmus across five specialist centres in the UK in order to present, for the first time, a consensus on investigation and clinical management.

POTENTIAL UTILITY OF FOVEAL MORPHOLOGY IN PRETERM INFANTS MEASURED USING HAND-HELD OPTICAL COHERENCE TOMOGRAPHY IN RETINOPATHY OF PREMATURITY SCREENING

PURPOSE

To investigate dynamic foveal morphology with postmenstrual age, in preterm infants with and without retinopathy of prematurity using hand-held optical coherence tomography, adjusting for gestational age (GA) and birthweight (BW).

METHODS

Prospective mixed cross-sectional/longitudinal observational study of 87 participants (23-36 weeks GA; n = 30 with, n = 57 without retinopathy of prematurity) using hand-held optical coherence tomography images (n = 278) acquired between 31 weeks and 44 weeks postmenstrual age excluding treated retinopathy of prematurity. Measurements included foveal width, area, depth, central foveal thickness, maximum slope, and parafoveal retinal thickness at 1,000 µm nasal and temporal to the central fovea.

RESULTS

Retinopathy of prematurity was significantly correlated with only foveal width in either GA or BW adjusted statistical models. In contrast, severity of prematurity (GA, BW) correlated with foveal area (P < 0.005), depth (P ≤ 0.001), and slope (P < 0.01), although central foveal thickness (P = 0.007) and parafoveal retinal thickness (P < 0.001) correlated with GA, but not with BW.

CONCLUSION

Foveal width is independent of GA and BW with potential in retinopathy of prematurity screening assessment using hand-held optical coherence tomography. Foveal morphology could be graded in prematurity during development, with possible implications for future management of preterm infants.

Reliability and Recommended Settings for Pediatric Circumpapillary Retinal Nerve Fiber Layer Imaging Using Hand-Held Optical Coherence Tomography

Purpose

To investigate feasibility and reliability of 3-dimensional full circumpapillary retinal nerve fiber layer (cpRNFL) analysis in children, with and without glaucoma, without the use of sedation and to recommend a protocol for hand-held optical coherence tomography use.

Methods

A cohort of pediatric glaucoma patients and normal children were imaged with hand-held optical coherence tomography to assess the feasibility of obtaining full cpRNFL. Two consecutive scans were acquired in a smaller sample to investigate test–retest repeatability and interassessor reproducibility. The cpRNFL thickness was assessed in four quadrants, at several visual angles from the optic nerve center.

Results

Scanning was attempted in both eyes of 90 children with pediatric glaucoma and 180 controls to investigate feasibility (mean age, 6.98 ± 4.42 years). Scanning was not possible in 68 eyes of glaucoma children mainly owing to nystagmus, unclear optical media, or high refractive errors. Where three-dimensional imaging was possible, success at obtaining full cpRNFL was 67% in children with glaucoma and 89% for controls. Seventeen children with pediatric glaucoma and 34 controls contributed to reliability analysis (mean age, 6.3 ± 3.63 years). For repeatability intraclass correlation coefficients across quadrants ranged from 0.63 to 0.82 at 4° and improved to 0.88 to 0.94 at 6°. Intraclass correlation coefficients for reproducibility were also highest at 6° (>0.97 across all quadrants).

Conclusions

We demonstrate that acquisition and measurement of cpRNFL thickness values using 3-dimensional hand-held optical coherence tomography volumes in awake children is both feasible and reliable and is optimal at 6° from optic nerve center.

Translational Relevance

Our recommended protocol provides guidance on how pediatric optic nerve pathologies are managed by clinicians.

Homozygous stop mutation in AHR causes autosomal recessive foveal hypoplasia and infantile nystagmus

Herein we present a consanguineous family with three children affected by foveal hypoplasia with infantile nystagmus, following an autosomal recessive mode of inheritance. The patients showed normal electroretinography responses, no signs of albinism, and no anterior segment or brain abnormalities. Upon whole exome sequencing, we identified a homozygous mutation (c.1861C>T;p.Q621*) in the aryl hydrocarbon receptor (AHR) gene that perfectly co-segregated with the disease in the larger family. AHR is a ligand-activated transcription factor that has been intensively studied in xenobiotic-induced toxicity. Further, it has been shown to play a physiological role under normal cellular conditions, such as in immunity, inflammatory response and neurogenesis. Notably, knockout of the Ahr gene in mouse impairs optic nerve myelin sheath formation and results in oculomotor deficits sharing many features with our patients: the eye movement disorder in Ahr-/- mice appears early in development and presents as conjugate horizontal pendular nystagmus. We therefore propose AHR to be a novel disease gene for a new, recessively inherited disorder in humans, characterized by infantile nystagmus and foveal hypoplasia.

Can Structural Grading of Foveal Hypoplasia Predict Future Vision in Infantile Nystagmus?: A Longitudinal Study

PURPOSE

To evaluate structural grading and quantitative segmentation of foveal hypoplasia using handheld OCT, versus preferential looking (PL), as predictors of future vision in preverbal children with infantile nystagmus.

DESIGN

Longitudinal cohort study.

PARTICIPANTS

Forty-two patients with infantile nystagmus (19 with albinism, 17 with idiopathic infantile nystagmus, and 6 with achromatopsia) were examined.

METHODS

Spectral-domain handheld OCT was performed in preverbal children up to 36 months of age. Foveal tomograms were graded using our 6-point grading system for foveal hypoplasia and were segmented for quantitative analysis: photoreceptor length, outer segment (OS) length, and foveal developmental index (FDI; a ratio of inner layers versus total foveal thickness). Patients were followed up until they could perform chart visual acuity (VA) testing. Data were analyzed using linear mixed regression models. Visual acuity predicted by foveal grading was compared with prediction by PL, the current gold standard for visual assessment in infants and young children.

MAIN OUTCOME MEASURES

Grade of foveal hypoplasia, quantitative parameters (photoreceptor length, OS length, FDI), and PL VA were obtained in preverbal children for comparison with future chart VA outcomes.

RESULTS

We imaged 81 eyes from 42 patients with infantile nystagmus of mean age 19.8 months (range, 0.9-33.4 months; standard deviation [SD], 9.4 months) at the first handheld OCT scan. Mean follow-up was 44.1 months (range, 18.4-63.2 months; SD, 12.0 months). Structural grading was the strongest predictor of future VA (grading: r = 0.80, F = 67.49, P < 0.0001) compared with quantitative measures (FDI: r = 0.74, F = 28.81, P < 0.001; OS length: r = 0.65; F = 7.94, P < 0.008; photoreceptor length: r = 0.65; F = 7.94, P < 0.008). Preferential looking was inferior to VA prediction by foveal grading (PL: r = 0.42, F = 3.12, P < 0.03).

CONCLUSIONS

Handheld OCT can predict future VA in infantile nystagmus. Structural grading is a better predictor of future VA than quantitative segmentation and PL testing. Predicting future vision may avert parental anxiety and may optimize childhood development.

Can Structural Grading of Foveal Hypoplasia Predict Future Vision in Infantile Nystagmus?: A Longitudinal Study

Purpose

To evaluate structural grading and quantitative segmentation of foveal hypoplasia using handheld OCT, versus preferential looking (PL), as predictors of future vision in preverbal children with infantile nystagmus.

Design

Longitudinal cohort study.

Participants

Forty-two patients with infantile nystagmus (19 with albinism, 17 with idiopathic infantile nystagmus, and 6 with achromatopsia) were examined.

Methods

Spectral-domain handheld OCT was performed in preverbal children up to 36 months of age. Foveal tomograms were graded using our 6-point grading system for foveal hypoplasia and were segmented for quantitative analysis: photoreceptor length, outer segment (OS) length, and foveal developmental index (FDI; a ratio of inner layers versus total foveal thickness). Patients were followed up until they could perform chart visual acuity (VA) testing. Data were analyzed using linear mixed regression models. Visual acuity predicted by foveal grading was compared with prediction by PL, the current gold standard for visual assessment in infants and young children.

Main Outcome Measures

Grade of foveal hypoplasia, quantitative parameters (photoreceptor length, OS length, FDI), and PL VA were obtained in preverbal children for comparison with future chart VA outcomes.

Results

We imaged 81 eyes from 42 patients with infantile nystagmus of mean age 19.8 months (range, 0.9–33.4 months; standard deviation [SD], 9.4 months) at the first handheld OCT scan. Mean follow-up was 44.1 months (range, 18.4–63.2 months; SD, 12.0 months). Structural grading was the strongest predictor of future VA (grading: r = 0.80, F = 67.49, P < 0.0001) compared with quantitative measures (FDI: r = 0.74, F = 28.81, P < 0.001; OS length: r = 0.65; F = 7.94, P < 0.008; photoreceptor length: r = 0.65; F = 7.94, P < 0.008). Preferential looking was inferior to VA prediction by foveal grading (PL: r = 0.42, F = 3.12, P < 0.03).

Conclusions

Handheld OCT can predict future VA in infantile nystagmus. Structural grading is a better predictor of future VA than quantitative segmentation and PL testing. Predicting future vision may avert parental anxiety and may optimize childhood development.

Assessment of the anterior segment of patients with primary congenital glaucoma using handheld optical coherence tomography

PURPOSE

To investigate the potential of handheld optical coherence tomography (HH-OCT) in assessing the anterior segment of the eye in patients with primary congenital glaucoma.

DESIGN

A prospective, case-controlled observational study.

PARTICIPANTS

Twenty-two patients with primary congenital glaucoma (PCG, 9 females and 13 males; mean age 4.36 ± 3.4 years) and age-, gender- and ethnicity-matched healthy participants.

METHODS

Anterior OCT was performed in all participants using a high-resolution HH SD-OCT device (Envisu 2300, Leica Microsystems, Germany) without anaesthesia or sedation.

RESULTS

Anterior HH-OCT in PCG visualised Haab's striae in 14.3%, uneven internal cornea in 9.5% and epithelial thickening in 11.9% of patients with central corneal thickening (CCT, p < 0.001). CCT was significantly correlated with the intraocular pressure (IOP, p < 0.001). The flat iris with a thin collarette zone was found in 59.5%, anterior iris insertion in 11.90% of eyes affected by PCG. Two independent examiners showed sensitivity and specificity of 87% and 77%, respectively, by instating iris thinning and flattening of the anterior profile.

CONCLUSIONS

Anterior HH-OCT has significant potential to improve diagnosis and management of PCG. Clinically relevant information can be obtained non-invasively and without sedation. High specificity makes anterior HH-OCT an important adjunct for management of PCG. Excellent visualisation of the iris insertion on OCT indicates potential for AS OCT to assist with surgical planning, including decision on the type of surgery and location of the incision.

Congenital monocular elevation deficiency associated with a novel TUBB3 gene variant

Background

The genetic basis of monocular elevation deficiency (MED) is unclear. It has previously been considered to arise due to a supranuclear abnormality.

Methods

Two brothers with MED were referred to Leicester Royal Infirmary, UK from the local opticians. Their father had bilateral ptosis and was unable to elevate both eyes, consistent with the diagnosis of congenital fibrosis of extraocular muscles (CFEOM). Candidate sequencing was performed in all family members.

Results

Both affected siblings (aged 7 and 12 years) were unable to elevate the right eye. Their father had bilateral ptosis, left esotropia and bilateral limitation of elevation. Chin up head posture was present in the older sibling and the father. Bell’s phenomenon and vertical rotational vestibulo-ocular reflex were absent in the right eye for both children. Mild bilateral facial nerve palsy was present in the older sibling and the father. Both siblings had slight difficulty with tandem gait. MRI revealed hypoplastic oculomotor nerve. Left anterior insular focal cortical dysplasia was seen in the older sibling. Sequencing of TUBB3 revealed a novel heterozygous variant (c.1263G>C, p.E421D) segregating with the phenotype. This residue is in the C-terminal H12 α-helix of β-tubulin and is one of three putative kinesin binding sites.

Conclusion

We show that familial MED can arise from a TUBB3 variant and could be considered a limited form of CFEOM. Neurological features such as mild facial palsy and cortical malformations can be present in patients with MED. Thus, in individuals with congenital MED, consideration may be made for TUBB3 mutation screening.

Detection and characterisation of optic nerve and retinal changes in primary congenital glaucoma using hand-held optical coherence tomography

Objective

To investigate (1) the feasibility of scanning the optic nerve (ON) and central retina with hand-held optical coherence tomography (HH-OCT) without sedation or anaesthesia in primary congenital glaucoma (PCG), (2) the characteristics of ON changes in comparison with adult primary open-angle glaucoma (POAG) in comparison with matched controls, (3) the sensitivity and specificity of ON parameters for diagnosis, and (4) changes of foveal morphology.

Methods and analysis

HH-OCT (Envisu 2300; Leica Microsystems) was used to investigate ON and foveal morphology of 20 children with PCG (mean age 4.64±2.79) and 10 adult patients with POAG (mean age 66.8±6.94), and compared with age-matched, gender-matched and ethnicity-matched healthy controls without sedation or anaesthesia.

Results

HH-OCT yielded useful data in 20 out of 24 young children with PCG. Patients with PCG had significantly deeper cup changes than patients with POAG (vs respective age-matched controls, p=0.014). ON changes in PCG are characterised by significant increase in cup depth (165%), increased cup diameter (159%) and reduction in rim area (36.4%) as compared with controls with high sensitivity (81.5, 74.1% and 88.9%, respectively) and specificity (85.0, 80.0% and 75.0%, respectively). Patients with PCG have a significantly smaller width of the macula pit (p<0.001) with non-detectable external limiting membrane.

Conclusion

HH-OCT has the potential to be a useful tool in glaucoma management for young children. We have demonstrated the use of HH-OCT in confirming a diagnosis of glaucoma within the studied cohort and found changes in disc morphology which characterise differently in PCG from POAG.

Reading Individual Words Within Sentences in Infantile Nystagmus

Purpose

Normal readers make immediate and precise adjustments in eye movements during sentence reading in response to individual word features, such as lexical difficulty (e.g., common or uncommon words) or word length. Our purpose was to assess the effect of infantile nystagmus (IN) on these adaptive mechanisms.

Methods

Eye movements were recorded from 29 participants with IN (14 albinism, 12 idiopathic, and 3 congenital stationary night blindness) and 15 controls when reading sentences containing either common/uncommon words or long/short target words. Parameters assessed included: duration of first foveation/fixation, number of first-pass and percentage second-pass foveations/fixations, percentage words skipped, gaze duration, acquisition time (gaze + nongaze duration), landing site locations, clinical and experimental reading speeds.

Results

Participants with IN could not modify first foveation durations in contrast to controls who made longer first fixations on uncommon words (P < 0.001). Participants with IN made more first-pass foveations on uncommon and long words (P < 0.001) to increase gaze durations. However, this also increased nongaze durations (P < 0.001) delaying acquisition times. Participants with IN reread shorter words more often (P < 0.005). Similar to controls, participants with IN landed more first foveations between the start and center of long words. Reading speeds during experiments were lower in IN participants compared to controls (P < 0.01).

Conclusions

People with IN make more first-pass foveations on uncommon and long words influencing reading speeds. This demonstrates that the "slow to see" phenomenon occurs during word reading in IN. These deficits are not captured by clinical reading charts.

Genome-Wide Association Study Identifies a Susceptibility Locus for Comitant Esotropia and Suggests a Parent-of-Origin Effect

Purpose

To identify genetic variants conferring susceptibility to esotropia. Esotropia is the most common form of comitant strabismus, has its highest incidence in European ancestry populations, and is believed to be inherited as a complex trait.

Methods

White European American discovery cohorts with nonaccommodative (826 cases and 2991 controls) or accommodative (224 cases and 749 controls) esotropia were investigated. White European Australian and United Kingdom cohorts with nonaccommodative (689 cases and 1448 controls) or accommodative (66 cases and 264 controls) esotropia were tested for replication. We performed a genome-wide case-control association study using a mixed linear additive model. Meta-analyses of discovery and replication cohorts were then conducted.

Results

A significant association with nonaccommodative esotropia was discovered (odds ratio [OR] = 1.41, P = 2.84 × 10-09) and replicated (OR = 1.23, P = 0.01) at rs2244352 [T] located within intron 1 of the WRB (tryptophan rich basic protein) gene on chromosome 21 (meta-analysis OR = 1.33, P = 9.58 × 10-11). This single nucleotide polymorphism (SNP) is differentially methylated, and there is a statistically significant skew toward paternal inheritance in the discovery cohort. Meta-analysis of the accommodative discovery and replication cohorts identified an association with rs912759 [T] (OR = 0.59, P = 1.89 × 10-08), an intergenic SNP on chromosome 1p31.1.

Conclusions

This is the first genome-wide association study (GWAS) to identify significant associations in esotropia and suggests a parent-of-origin effect. Additional cohorts will permit replication and extension of these findings. Future studies of rs2244352 and WRB should provide insight into pathophysiological mechanisms underlying comitant strabismus.