Congenital anomalies of the optic disc: insights from optical coherence tomography imaging

Characteristic deviations of the optic disc and macula in optic nerve hypoplasia based on OCT

PURPOSE

The purpose of this study was to evaluate the optic disc and macula in a large cohort of patients with different severity of optic nerve hypoplasia (ONH) using high-resolution spectral domain optical coherence tomography (SD-OCT).

METHODS

In total, 36 patients (52 ONH eyes and 17 fellow eyes in unilateral cases) and 45 healthy right eyes from 45 controls were evaluated. All patients underwent an examination to confirm the diagnosis. SD-OCT images of the disc and macula were obtained and analysed both quantitatively and qualitatively.

RESULTS

OCT in ONH eyes demonstrated a shorter disc diameter (1061 ± 375 μm vs. 1751 ± 221 μm, p < 0.001), shallower mean cup depth (427 ± 171 μm vs. 551 ± 152 μm, p = 0.01), thinner ganglion cell complex (GCC) perifoveally (47.3 ± 13.0 μm, 60.8 ± 6.0 μm, p < 0.001) and reduced foveal depth (61 ± 36 μm, 119 ± 19 μm, p < 0.001) compared to control eyes. Qualitative analysis showed that 1/3rd of ONH eyes lacked signs of an optic cup, and 2/3rd had reduced or no sign of a foveal pit. Fellow eyes had shorter disc diameter (1446 ± 404 μm vs. 1751 ± 221 μm, p = 0.004) and reduced foveal depth (93 ± 27 μm vs. 119 ± 19 μm, p < 0.001) but similar GCC thickness (60.8 ± 7.1 μm vs. 60.8 ± 6.0 μm, p = 0.738) compared to controls. Disc diameter showed the best correlation with visual acuity in ONH eyes (ρ = 0.517, p < 0.001).

CONCLUSION

ONH eyes have reduced GCC thickness and reduced or no foveal pit. Fellow eyes in presumed unilateral cases have a smaller disc diameter and reduced foveal depth compared to controls, suggesting the possibility of subclinical/mild disease. However, GCC thickness was normal. The correlation between structure and visual function is not always straightforward.

Congenital Optic Disc Anomalies: Insights from Multimodal Imaging

In this comprehensive review, we delve into the significance of multimodal imaging in diagnosing and managing complications of congenital optic disc anomalies. While the fundus examination is the gold standard tool in the diagnosis of these pathologies, spectral domain (SD) optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA) could shed light on the pathogenesis and treatment. Moreover, this review seeks to offer a comprehensive insight into the multimodal approach of these rare congenital pathologies. In conclusion, congenital anomalies of the optic nerve represent a major challenge for ophthalmologists. Further research could be useful to clarify the pathophysiology of these diseases and define a correct and more specific treatment approach.

Optic disc and retinal vascular features in first 6 years of Chinese children

Purpose

Retinal microvasculature plays an important role in children's fundus lesions and even in their later life. However, little was known on the features of normal retina in early life. The purpose of this study was to explore the normal retinal features in the first 6 years of life and provide information for future research.

Methods

Children, aged from birth to 6 years old and diagnosed with various unilateral ocular diseases were included. Venous phase fundus fluorescein angiography images with the optic disc at the center were collected. Based on the ResUNet convolutional neural network, optic disc and retinal vascular features in the posterior retina were computed automatically.

Results

A total of 146 normal eyes of 146 children were included. Among different age groups, no changes were shown in the optic disc diameter (y = -0.00002x + 1.362, R² = 0.025, p = 0.058). Retinal vessel density and fractal dimension are linearly and strongly correlated (r = 0.979, p < 0.001). Older children had smaller value of fractal dimension (y = -0.000026x + 1.549, R²= 0.075, p = 0.001) and narrower vascular caliber if they were less than 3 years old (y = -0.008x + 84.861, R²= 0.205, p < 0.001). No differences were in the density (y = -0.000007x + 0.134, R²= 0.023, p = 0.067) and the curvature of retinal vessels (lnC = -0.00001x - 4.657, R²= 0.001, p = 0.667).

Conclusions

Age and gender did not impact the optic disc diameter, vessel density, and vessel curvature significantly in this group of children. Trends of decreased vessel caliber in the first 3 years of life and decreased vessel complexity with age were observed. The structural characteristics provide information for future research to better understand the developmental origin of the healthy and diseased retina.

Optical Coherence Tomography Can Predict Visual Acuity in Children with Optic Nerve Hypoplasia

PURPOSE

Optic nerve hypoplasia (ONH) is a common cause of visual impairment in children. Clinical complexity can cause diagnostic delay and difficulties predicting visual outcome. We evaluated whether optical coherence tomography (OCT) can improve the diagnosis and prediction of vision.

METHODS

Thirty-seven eyes with ONH from 12 girls and 8 boys, median age 10.5 years (range 2.8-18.9 years), were included in this cross-sectional cohort study. The majority, 17/20, had bilateral ONH. Ophthalmological assessments included best corrected visual acuity (BCVA), fundus photography, measurement of the peripapillary retinal nerve fibre layer (pRNFL), macular ganglion cell complex (GCC), Bruch's membrane opening (BMO) and visual fields. We compared OCT parameters with comparison data collected on 140 healthy individuals 5 to 25 years old. Pearson's correlation coefficient was used to determine the correlation of OCT parameters and BCVA.

RESULTS

OCT demonstrated thinner mean pRNFL (p < 0.001) and mean GCC compared to the reference material (p < 0.001). BCVA displayed a strong or moderate correlation to pRNFL and to all sectors of the GCC except the inferotemporal. BCVA correlated strongly to Bruch's membrane opening (BMO) (0.71, p < 0.001), and moderately to the Zeki ratio (-0.52, p < 0.001). Multivariate analyses showed that BMO explained 48% of the variance in BCVA. Visual fields correlated strongly to pRNFL and GCC thickness. GCC thinning corresponded to visual field defects presence and location.

CONCLUSION

OCT can facilitate the diagnosis of ONH. Parameters such as pRNFL, GCC and BMO can be predictors of visual acuity whereas GCC and pRNFL thinning can indicate location and severity of visual field defects.

Pathophysiological Heterogeneity of the BBSOA Neurodevelopmental Syndrome

The formation and maturation of the human brain is regulated by highly coordinated developmental events, such as neural cell proliferation, migration and differentiation. Any impairment of these interconnected multi-factorial processes can affect brain structure and function and lead to distinctive neurodevelopmental disorders. Here, we review the pathophysiology of the Bosch–Boonstra–Schaaf Optic Atrophy Syndrome (BBSOAS; OMIM 615722; ORPHA 401777), a recently described monogenic neurodevelopmental syndrome caused by the haploinsufficiency of NR2F1 gene, a key transcriptional regulator of brain development. Although intellectual disability, developmental delay and visual impairment are arguably the most common symptoms affecting BBSOAS patients, multiple additional features are often reported, including epilepsy, autistic traits and hypotonia. The presence of specific symptoms and their variable level of severity might depend on still poorly characterized genotype–phenotype correlations. We begin with an overview of the several mutations of NR2F1 identified to date, then further focuses on the main pathological features of BBSOAS patients, providing evidence—whenever possible—for the existing genotype–phenotype correlations. On the clinical side, we lay out an up-to-date list of clinical examinations and therapeutic interventions recommended for children with BBSOAS. On the experimental side, we describe state-of-the-art in vivo and in vitro studies aiming at deciphering the role of mouse Nr2f1, in physiological conditions and in pathological contexts, underlying the BBSOAS features. Furthermore, by modeling distinct NR2F1 genetic alterations in terms of dimer formation and nuclear receptor binding efficiencies, we attempt to estimate the total amounts of functional NR2F1 acting in developing brain cells in normal and pathological conditions. Finally, using the NR2F1 gene and BBSOAS as a paradigm of monogenic rare neurodevelopmental disorder, we aim to set the path for future explorations of causative links between impaired brain development and the appearance of symptoms in human neurological syndromes.

Case Report: Bilateral Cecocentral Visual Field Defect Secondary to Congenital Optic Disc Pit

SIGNIFICANCE

Congenital optic disc pits are known to cause complications, commonly maculopathy due to retinoschisis and/or neurosensory retinal detachment. Retinal nerve fiber layer defects with associated visual field defects without maculopathy are another complication and can result in decreased visual function but have rarely been reported in the literature, especially bilaterally.

PURPOSE

This case report describes a patient with bilateral cecocentral visual field defects due to congenital optic nerve pits without associated maculopathy.

CASE REPORT

A 42-year-old Black man presented with blur symptoms at near uncorrected. Of note, there was no history of substance abuse or nutritional deficiencies. Best-corrected acuities were 20/20 in the right eye and 20/30 in the left eye. Clinical examination revealed bilateral focal grayish depression of the temporal optic nerve cup with associated papillomacular retinal nerve fiber layer defects. Optical coherence tomography (OCT) imaging revealed bilateral focal excavation of the temporal cup, temporal thinning of the retinal nerve fiber layer, and correlated binasal thinning of the ganglion cell complex, in the absence of retinoschisis or neurosensory detachment. Threshold visual field testing revealed stable bilateral cecocentral visual field defects. A diagnosis of bilateral cecocentral visual field defect secondary to congenital optic disc pits was made based on the patient's history and clinical examination.

CONCLUSIONS

A cecocentral visual field defect, unrelated to maculopathy, is a less common complication of congential optic disc pits that can cause decreased visual function. This case report provides evidence of this bilateral ocular condition and reviews the reported clinical, OCT, and threshold visual field manifestations of the disease. Specifically, spectral-domain OCT ganglion cell analysis seems useful in localizing the visual field defect.

Tilted disc syndrome (TDS): New hypotheses for posterior segment complications and their implications in other retinal diseases

Tilted disc syndrome (TDS) is considered a congenital anomaly due to a delayed closure of the embryonic fissure. It is characterized by an oblique orientation of the axis of the optic disc, associated with other posterior pole anomalies such as inferior crescent, situs inversus and inferior staphyloma. The aim of this review was to summarize the data supporting the current hypotheses for the pathogenesis of TDS, and its anatomical and functional clinical consequences. Recent imaging techniques, such as magnetic resonance imaging, wide-field fundus imaging, and 2- and 3-D optical coherence tomography have provided a new perspective on TDS and its complications. Different abnormalities have previously been reported, both in the anterior and posterior segments. The focus was on vision-threatening chorioretinal changes or complications, including choroidal neovascularization and serous retinal detachments and their therapeutic options. Based on clinical observations, assumptions were proposed to understand the occurrence of complications such as chorioretinal degenerative changes, choroidal neovascularization and polypoidal choroidal vasculopathy, macular serous retinal detachment, myopic foveoschisis and chorioretinal folds. These hypotheses could be referred to as the curvature "breaking point" hypothesis, the uneven growth "tractional" hypothesis, the "container-content" imbalance hypothesis, and the "choroidal funnel" hypothesis. Because these complications could also occur in other contexts, understanding the pathogenesis of TDS complications could help to understand their pathophysiology.

Morning glory disc anomaly-associated maculopathy: multimodal imaging

Morning glory disc anomaly (MGDA) is most commonly found in white females in childhood with reduced vision. One in two cases have been reported to develop maculopathy or posterior pole retinal detachment as they grow older. The pathophysiology of MGDA-associated maculopathy is not well understood.We describe a 31-year-old black woman, who presented with gradual reduction of vision in the right eye due to MGDA-associated maculopathy. We identified morphological characteristics of the optic disc and macula with multicolour and optical coherence tomography imaging.We speculate that the centripetal inner retina traction and cerebrospinal fluid pressure fluctuation play an important role in inner retinal fluid accumulation in the pathology of retinoschisis in MGDA. Further studies will shed some light of a potential cause-and-effect relationship between MGDA and retinoschisis.

Multimodal Imaging of Large Optic Disc Coloboma: A Report of Three Cases

Optic disc coloboma (ODC) is a rare congenital anomaly of the optic nerve. Optical coherence tomography (OCT) helps to monitor the complications when there is associated retinoschisis, retinal detachment, or peripapillary neovascularization, while being minimally invasive. OCT angiography could help to better understand this entity from a vascular perspective. We report multimodal imaging of 3 children with large ODC associated with cat eye syndrome, CHARGE syndrome (coloboma, heart defects, atresia choanae, growth retardation, genital abnormalities, and ear abnormalities), and branchio-oculo-facial syndrome.

A SIX6 Nonsense Variant in Golden Retrievers with Congenital Eye Malformations

Causative genetic variants for more than 30 heritable eye disorders in dogs have been reported. For other clinically described eye disorders, the genetic cause is still unclear. We investigated four Golden Retriever litters segregating for highly variable congenital eye malformations. Several affected puppies had unilateral or bilateral retina dysplasia and/or optic nerve hypoplasia. The four litters shared the same father or grandfather suggesting a heritable condition with an autosomal dominant mode of inheritance. The genome of one affected dog was sequenced and compared to 601 control genomes. A heterozygous private nonsense variant, c.487C>T, was found in the SIX6 gene. This variant is predicted to truncate about a third of the open reading frame, p.(Gln163*). We genotyped all available family members and 464 unrelated Golden Retrievers. All three available cases were heterozygous. Five additional close relatives including the common sire were also heterozygous, but did not show any obvious eye phenotypes. The variant was absent from the 464 unrelated Golden Retrievers and 17 non-affected siblings of the cases. The SIX6 protein is a homeobox transcription factor with a known role in eye development. In humans and other species, SIX6 loss of function variants were reported to cause congenital eye malformations. This strongly suggests that the c.487C>T variant detected contributed to the observed eye malformations. We hypothesize that the residual amount of functional SIX6 protein likely to be expressed in heterozygous dogs is sufficient to explain the observed incomplete penetrance and the varying severity of the eye defects in the affected dogs.

Estimation of angle kappa and pupil barycentre configuration in myopic tilted disc syndrome

BACKGROUND

To evaluate the angle kappa and pupil barycentre configuration in patients with myopic tilted disc syndrome (TDS).

METHODS

Thirty-five eyes of 35 patients with TDS were included in the study. Thirty-five eyes of 35 age- and sex-matched healthy subjects were enrolled in the control group. All measurements were performed with the Lenstar LS 900. Angle kappa was calculated according to Pythagorean theorem using the x and y co-ordinates of the pupil centre. Pupil dx and pupil dy values (pupil dx: x co-ordinate of pupil centre relative to corneal apex, pupil dy: y co-ordinate of pupil centre relative to corneal apex) were used to evaluate the pupil barycentre configuration. Central corneal thickness, white to white (cornea diameter), pupil diameter, anterior chamber depth, lens thickness, and axial length were also measured.

RESULTS

The calculated mean angle kappa distance was 0.27 ± 0.15 mm in the TDS group and 0.29 ± 0.23 mm in the control group (p = 0.42). The mean pupil dx was -0.01 ± 0.24 mm in the TDS group and -0.17 ± 0.14 mm in the control group (p = 0.006). The mean pupil dy was -0.02 ± 0.13 mm in the TDS group and -0.05 ± 0.22 mm in the control group (p = 0.65).

CONCLUSIONS

The pupil barycentre in TDS cases was statistically significantly closer to the corneal vertex on the horizontal plane compared to the control group. However, there was no statistically significant differences in terms of angle kappa and pupil dy values between the groups. According to our results, refractive surgery can be performed safely with respect to complications related to decentration of ablation zone and decentration of multifocal intraocular lenses in these groups of patients.

Optical coherence tomography: A guide to interpretation of common macular diseases

Optical coherence tomography is a quick, non invasive and reproducible imaging tool for macular lesions and has become an essential part of retina practice. This review address the common protocols for imaging the macula, basics of image interpretation, features of common macular disorders with clues to differentiate mimickers and an introduction to choroidal imaging. It includes case examples and also a practical algorithm for interpretation.