The clinical evaluation of infantile nystagmus: What to do first and why

ACR Appropriateness Criteria® Orbital Imaging and Vision Loss-Child

Orbital disorders in children consist of varied pathologies affecting the orbits, orbital contents, visual pathway, and innervation of the extraocular or intraocular muscles. The underlying etiology of these disorders may be traumatic or nontraumatic. Presumed location of the lesion along with the additional findings, such as eye pain, swelling, exophthalmos/enophthalmos, erythema, conjunctival vascular dilatation, intraocular pressure, etc, help in determining if imaging is needed, modality of choice, and extent of coverage (orbits and/or head). Occasionally, clinical signs and symptoms may be nonspecific, and, in these cases, diagnostic imaging studies play a key role in depicting the nature and extent of the injury or disease. In this document, various clinical scenarios are discussed by which a child may present with an orbital or vision abnormality. Imaging studies that might be most appropriate (based on the best available evidence or expert consensus) in these clinical scenarios are also discussed. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Managing the apparently blind child presenting in the first year of life: A review

Severe vision impairment and blindness in childhood have a significant health burden on the child, family and society. This review article seeks to provide a structured framework for managing the apparently blind child presenting in the first year of life, starting from a comprehensive history and examination. Different investigation modalities and the increasingly important role of genetics will also be described, in addition to common causes of severe vision impairment. Crucially, a systematic approach to the blind infant is key to correct diagnoses and timely management. Incorrect diagnoses can be costly to all involved, however it is important to note that diagnoses can change with ongoing follow-up and investigations. Furthermore, the modern age of ophthalmology requires a multi-disciplinary approach and close collaboration with specialists including paediatricians, neurologists and geneticists, in addition to rehabilitation and low vision services, to ensure the best care for these vulnerable infants.

Modernizing the evaluation of infantile nystagmus: the role of handheld optical coherence tomography

BACKGROUND

Infantile nystagmus syndrome can be associated with an afferent problem (anterior or posterior segment) or constitute an isolated idiopathic disorder. With a normal ophthalmic examination, current guidelines recommend electroretinography (ERG) rather than magnetic resonance (MRI) for preliminary workup. Given the limited use of optical coherence tomography (OCT) in preverbal children, the purpose of this study was to evaluate the role of handheld OCT (HH-OCT) in the initial diagnostic evaluation of infantile nystagmus.

METHODS

In this cross-sectional case series, the medical records of all children with infantile nystagmus and HH-OCT imaging at the Duke Eye Center from August 2016 to July 2021 were retrospectively reviewed. Children with anterior segment disorders or obvious retina/optic nerve structural pathology, bilateral ophthalmoplegia, or Down syndrome were excluded. Two masked pediatric ophthalmologists graded HH-OCT images for optic nerve head and macular abnormalities. A neuro-ophthalmologist reviewed clinical findings of each patient's presenting visit and recommended appropriate testing (MRI vs ERG), initially without, and again with HH-OCT image review.

RESULTS

A total of 39 cases were included, with mean presenting age of 1.3 years. Final diagnoses included retinal or foveal abnormalities (7), optic nerve pathology (13), idiopathic (10), or unknown (9). HH-OCT findings included optic nerve hypoplasia (1), optic nerve elevation (3), persistence of the inner layers at the fovea (9), thin ganglion cell layer (8), ellipsoid zone abnormality (3), and thin choroid (1). HH-OCT findings altered initial clinical-only management in 16 cases (41%), including avoiding MRI (5) and ERG (10) testing.

CONCLUSIONS

Our results suggest that HH-OCT has the potential to augment and streamline the evaluation of infantile nystagmus.

Nystagmus in the B6(CG)Tyr(c-2J)/J Albino Mouse: A Functional and RNA-Seq Analysis

Purpose

Infantile nystagmus syndrome (INS) is a gaze-holding disorder characterized by conjugate, uncontrolled eye oscillations that can result in significant visual acuity loss. INS is often associated with albinism, but the mechanism is unclear. Albino mice have nystagmus; however, a pigmented mouse with a tyr mutation making it phenotypically albino, the B6(CG)-Tyr(c-2J)/J (B6 albino), had not been tested. We tested optokinetic response (OKR) in B6 albino and control mice. RNA-Seq was performed on extraocular muscles (EOM), tibialis anterior (TA) muscle, abducens (CN6), and oculomotor (CN3) neurons to uncover molecular differences that may contribute to nystagmus.

Methods

OKR was measured using an ISCAN system. RNA was isolated from four tissues to identify differentially expressed genes and validated with qPCR and immunohistochemistry. Ingenuity pathway analyses identified top biological pathways.

Results

All B6 albino mice tested had nystagmus. Differential RNA expression analysis showed 383 genes differentially expressed in EOM, 70 in CN3, 20 in CN6, and 639 in the TA. Two genes were differentially expressed in all four tissues: wdfy1 and nnt. Differences were validated by qPCR and immunostaining.

Conclusions

The tyr mutation in B6 albino mice, genotypically pigmented and phenotypically albino, is sufficient to result in spontaneous nystagmus. The two genes with decreased expression in the B6 albino tissues examined, wdfy1 and nnt, have been implicated in mitochondrial dysfunction and stem cell maintenance in other systems. Their function in extraocular muscle is unknown. These studies suggest that this mouse model of nystagmus may allow molecular identification of candidate nystagmus-related genes.

CACNA1F-related synaptic dysfunction: challenges diagnosing congenital stationary night blindness presenting without night blindness

OBJECTIVE

To describe pediatric patients with CACNA1F-associated incomplete X-linked congenital stationary night blindness presenting without nyctalopia, and review the causes leading to diagnosis delay.

DESIGN

Retrospective cohort.

METHODS

This was set in a single institution between 2004 and 2019. There were12 patients. The intervention or observation procedures used were clinical course, visual acuity, refractive error, images, electrophysiology, genetic testing, pedigree. The main outcome measures were cohort description and causes of diagnosis delay.

RESULTS

For these 12 cases, the referring diagnosis was congenital nystagmus (7), reduced best-corrected visual acuity (BCVA, 4), and progressive myopia (1). Nyctalopia was not a presenting symptom and developed in 4 patients during follow-up. Seven patients presented with nystagmus. All patients developed early-onset myopia. Myopia progressed more rapidly before age 6 than after (average 1.14 D vs 0.25 D) (p = 0.0033). The average final BCVA was 20/50 (20/30-20/150). Vision at presentation was correlated with final visual acuity (r2 = 0.87, p = 5.4E-06). The first cycloplegic refraction was correlated to the final refractive error (r2 = 0.49, p = 0.009). Patients with nystagmus had worse BCVA on average. Full-field electroretinogram was abnormal and diagnostic in all cases, as confirmed by genetic testing. The average time to diagnosis was 4.2 years, and the average age at diagnosis was 7.9 years. The delay in diagnosis was due to the absence of nyctalopia, not performing an electroretinogram and/or an alternative diagnosis.

CONCLUSIONS

In children, CACNA1F-associated synaptic dysfunction does not usually present with night blindness. It should be suspected in male patients with early-onset myopia, especially with a history of nystagmus.

Human equivalent doses of L-DOPA rescues retinal morphology and visual function in a murine model of albinism

L-DOPA is deficient in the developing albino eye, resulting in abnormalities of retinal development and visual impairment. Ongoing retinal development after birth has also been demonstrated in the developing albino eye offering a potential therapeutic window in humans. To study whether human equivalent doses of L-DOPA/Carbidopa administered during the crucial postnatal period of neuroplasticity can rescue visual function, OCA C57BL/6 J-c2J OCA1 mice were treated with a 28-day course of oral L-DOPA/Carbidopa at 3 different doses from 15 to 43 days postnatal age (PNA) and for 3 different lengths of treatment, to identify optimum dosage and treatment length. Visual electrophysiology, acuity, and retinal morphology were measured at 4, 5, 6, 12 and 16 weeks PNA and compared to untreated C57BL/6 J (WT) and OCA1 mice. Quantification of PEDF, βIII-tubulin and syntaxin-3 expression was also performed. Our data showed impaired retinal morphology, decreased retinal function and lower visual acuity in untreated OCA1 mice compared to WT mice. These changes were diminished or eliminated when treated with higher doses of L-DOPA/Carbidopa. Our results demonstrate that oral L-DOPA/Carbidopa supplementation at human equivalent doses during the postnatal critical period of retinal neuroplasticity can rescue visual retinal morphology and retinal function, via PEDF upregulation and modulation of retinal synaptogenesis, providing a further step towards developing an effective treatment for albinism patients.

Genetic testing for infantile nystagmus syndrome with or without associated findings

PURPOSE

To review the published literature assessing the clinical utility of genetic testing in individuals with infantile nystagmus syndrome (INS), defined as binocular conjugate nystagmus and onset prior to 6 months of age, with or without associated findings.

METHODS

A literature search was last conducted in October 2022. The results were limited to articles published in English. The search yielded 517 abstracts, of which 72 papers were reviewed in full text. Of these papers, 4 met the criteria for inclusion and were graded by a study methodologist.

RESULTS

The 4 studies that met inclusion criteria used next-generation sequencing with gene panels ranging from 31 to 336 genes. The overall molecular diagnostic rate ranged from 35% to 60% in the included studies, although the yield was higher when genetic testing was guided by clinical phenotyping (approximately 80%) and in the subsets of patients with a family history (up to 88%). As many as 30% of patients tested had a reclassification of the diagnosis based on the genetic testing results.

CONCLUSIONS

Genetic testing has the potential to provide a definitive diagnosis and identify treatable conditions in patients presenting with INS, especially when considered in conjunction with clinical phenotyping and family history.

The long-term outcomes of the Anderson-Kestenbaum procedure

Introduction

Nystagmus is an involuntary, conjugated, rhythmic movement of the eye that can be idiopathic or secondary to ocular or neurologic pathologies. Patients with nystagmus often have a position of gaze in which their symptoms are dampened or absent, referred to as the "null zone." The Anderson-Kestenbaum procedure is a bilateral recess-resect procedure of the four horizontal rectus muscles which aims to bring the null position into the primary gaze. This study aims to further elucidate long-term outcomes and factors associated with optimal postoperative outcomes.

Methods

Patients with a diagnosis of nystagmus and a surgical code for strabismus between June 1990 and August 2017 were considered for inclusion in the study. Patients were included if they had undergone the Anderson-Kestenbaum procedure and had follow-up lasting at least 24 months post-operatively. Data collected included demographic information, characteristics of the nystagmus, underlying etiology of nystagmus, and pre-and post-operative measurements.

Results

25 patients were included. At their last recorded follow-up, 44% of patients achieved an optimal surgical outcome -an abnormal head position of 10 degrees or less. 88% of patients showed an overall improvement in their head posture at the last follow-up. The absence of an abnormal head position at the visit closest to 24 months post-operatively was found to be significantly associated with the lack of a significant head position at the last follow-up visit. Optimal surgical outcomes were not significantly associated with the underlying diagnosis, the direction of the abnormal head position, or the type of nystagmus.

Discussion

The relatively long follow-up of this cohort allows this study to further elucidate the long-term outcomes of the Anderson-Kestenbaum procedure. Overall, our results suggest that although improvement in head position post-operatively is likely, it is still expected that many patients will have a residual abnormal head position after the procedure. The results of this study are helpful in counseling patients, especially knowing that if they do not have a significant head position at 24 months follow-up, they are unlikely to develop one. However, due to the small sample size, larger cohorts and more standardized follow-up may provide further insight into the procedure's outcomes.

[Human genetic diagnostics in hereditary eye diseases : What does the ophthalmologist need to know]

Hereditary eye disorders can affect all ocular structures and can be accompanied by structural malformations (e.g. coloboma) or functional disorders (e.g. retinal dystrophy). Ocular phenotypes can also be the presenting symptom of many complex syndromic disorders. The majority of hereditary eye disorders are extremely heterogeneous but can be routinely diagnosed by modern high-throughput sequencing technologies. Molecular testing is highly important not only in in the evaluation of differential diagnoses but is also of increasing relevance due to individual treatment options.

Abnormal Eye Movements in a Young Girl

A 5-year-old girl was referred for nystagmus with a history of esophageal atresia, small bowel obstruction, mild cognitive impairment, low tone, and increased reflexes. Alternating vertical and torsional nystagmus was noted. What would you do next?

Infantile nystagmus without overt eye abnormality: Early features and neuro-ophthalmological diagnosis

AIM

To analyse the neuro-ophthalmological data of children referred for further work-up of infantile nystagmus where ophthalmological evaluation had not achieved a diagnosis.

METHOD

We retrospectively reviewed medical records of patients presenting with infantile nystagmus at our institution between 2007 and 2019. Inclusion criteria were onset before 6 months of age, availability of complete ophthalmic examination, visual electrophysiological tests, and neurological examination. Children with a previous definite ophthalmological diagnosis at onset and those with uncertain nystagmus onset age were not recruited.

RESULTS

Out of 142 infants (mean age at nystagmus onset 3.6 mo, SD 1.7, range 0-6 mo; 56 females, 86 males), 23% had neurological nystagmus, 7% mixed neurological and sensory nystagmus, 48% sensory defect, and 22% idiopathic infantile nystagmus. The neurological diagnoses were inborn errors of metabolism, white matter genetic disorders, and brain malformations. The prevalent diagnosis in the sensory defect subgroup was retinal dystrophy.

INTERPRETATION

Infantile nystagmus without diagnostic ocular findings may be due to neurological, retinal, and optic nerve disorders or be a benign idiopathic condition. In infants with and without neurological abnormalities, the search for a sensory defect should include visual electrophysiology performed early in the diagnostic pathway.

WHAT THIS PAPER ADDS

Infantile nystagmus without diagnostic ophthalmological signs has an underlying neurological cause in 30% of cases. Neurological diagnoses include congenital brain malformations, and metabolic and genetic disorders. Sensory defects are part of systemic neurological disorders in 23% of infants. Electrophysiology is useful when ophthalmological examination is uninformative.

A clinical and electrophysiological case study of a child with a novel frame shift mutation in the CACNA1F and missense variation of RIMS1 genes

PURPOSE

The purpose of this paper is to present a case study illustrating the importance of electrophysiological investigation in the diagnosis and serial monitoring of isolated congenital nystagmus.

RESULTS

Serial electophysiological monitoring was undertaken in the male proband over a 9-year period commencing with initial assessment at 12 weeks of age: Skin electroretinograms (sERGs) were initially absent but subsequently revealed low-amplitude responses, electronegative morphologies and notched flicker responses suggestive of incomplete congenital stationary night blindness (CSNB2), but with an absent dark-adapted rod-specific response, while flash visual evoked potentials (fVEPs) demonstrated persistent crossed asymmetry, typical of albinoid misrouting of the optic nerves. Molecular investigation confirmed a novel hemizygous frame shift mutation in the CACNA1F gene, considered to be pathogenic and causative of X-linked CSNB2; additionally, a novel heterozygous missense variation in one copy of the RIMS1 gene was identified, pathogenic mutations of which underpin late-onset autosomal dominant cone-rod dystrophy (type 7). Segregation studies confirmed maternal inheritance of both mutations in the clinically asymptomatic mother in whom depressed rod-specific responses were confirmed on sERG. The child's visual acuity has remained stable as have the sERGs which have been verified by recordings using scleral electrodes.

CONCLUSIONS

The importance of recording ERGs as part of evaluating infants who present with nystagmus, even with a normal fundus appearance, is supported. Further, sERGs were able to distinguish an apparent variant of CSNB2 and could give consistent results over many years. FVEP results add to the evidence that albinoid misrouting of the optic nerves may occur in cases of CSNB2. ERGs and fVEPs can provide valuable information in discriminating the relative diagnostic importance of multiple genetic abnormalities.

Cross-sectional observational analysis of the genetic referral practices across pediatric ophthalmology outpatient departments in an urban setting

Purpose

To analyze the genetic referral practices of pediatric ophthalmologists in an urban setting.

Methods

(1) The first limb of the study: cross-sectional, observational study among children visiting the outpatient department of pediatric ophthalmology across five centers in Mumbai. All pediatric patients were screened separately by pediatric ophthalmologists and a clinical geneticist for their ophthalmic and systemic complaints. Children were marked for referral to genetics (RTG) by both the specialists based on identification of distinctive features (red flag) and were requested to meet a local geneticist. (2a) Twenty-three months later, patients who had been marked for RTG were contacted telephonically to follow-up if they had met the geneticist. (2b) Additionally, the last 20 proformas from each center were checked retrospectively to note the RTG marked by the ophthalmologist alone.

Results

(1) In the first aspect of the study, 126 patients (male: female = 1.2:1) were included. Forty-nine (38.3%) patients were referred for genetic evaluation, of which three (6.1%), 31 (63.26%), and 15 (30.6%) cases were referred by the ophthalmologist alone, geneticist alone, and by both the specialists, respectively. Glaucoma (100%), nystagmus (86%), and leukocoria (83%) were the most prominent ocular diagnoses in cases referred for genetic evaluation. Facial dysmorphism (55.1%) and neurodevelopmental delays (51%) were among the most common systemic red flags found in patients referred to genetics. (2a) Twenty-three months later, on contacting the 49 patients marked for RTG, only one family had met the geneticist. (2b) Retrospective evaluation of 100 proformas: only three patients were marked for RTG by ophthalmologist alone.

Conclusion

This study found that the genetic referrals by pediatric ophthalmologist were far lesser than those by geneticist. The study highlights an area of knowledge gap among pediatric ophthalmologists, prompting a need for heightened awareness in this area.

Nystagmus in Down Syndrome – a Retrospective Notes Review

Introduction:

Nystagmus has been reported in up to 30% of people with Down Syndrome (DS), and yet is still not well understood. Our study aims to characterise the clinical features of patients with DS and nystagmus.

Methods:

A retrospective medical-records review was conducted of all patients with a diagnosis of DS and nystagmus seen at Moorfields Eye Hospital over a ten-year period.

Results:

Fifty-one subjects were identified, with complete data in 48. The mean age at presentation was 5.1 years (range 0–26 years). The mean binocular LogMAR visual acuity was 0.55(95%CI 0.53–0.57), mean refractive error was –1.8 Dioptre Sphere, DS (95% CI – 5.251.63) with –1.2 Dioptre Cylinder, DC (95% CI – 1.6–0.7). Ocular misalignment was found in 50% of patients. A diagnosis of Fusion Maldevelopment Nystagmus Syndrome (FMNS) was made in 6.3%, Infantile Nystagmus Syndrome (INS) in 8.4% and ABducting nystagmus/Inter-Nuclear Ophthalmoplegia (INO) in 2.1%. The descriptive term ‘Manifest Horizontal Nystagmus’(MNH) was used in the majority, highlighting the difficulties in clinically differentiating the subtypes of nystagmus in DS. Eleven patients had associated cataract. Additional diagnoses unrelated to DS were made in 10.4%.

Conclusions:

The most frequent type of nystagmus in our cohort was ‘presumed’ INS. This study highlights the importance of differentiating between FMNS and INS (with a latent component), so that further investigations can be performed as appropriate. Almost 25% had associated cataract, and a further 10% other diagnoses un-associated to DS. Despite INS being known to be associated with DS, further investigations may be required in a small subset with true INS after careful clinical assessment and use of eye movement recordings (where available).

Ocular manifestations in patients with inborn errors of intracellular cobalamin metabolism: a systematic review

Inherited disorders of cobalamin (cbl) metabolism (cblA-J) result in accumulation of methylmalonic acid (MMA) and/or homocystinuria (HCU). Clinical presentation includes ophthalmological manifestations related to retina, optic nerve and posterior visual alterations, mainly reported in cblC and sporadically in other cbl inborn errors.We searched MEDLINE EMBASE and Cochrane Library, and analyzed articles reporting ocular manifestations in cbl inborn errors. Out of 166 studies a total of 52 studies reporting 163 cbl and 24 mut cases were included. Ocular manifestations were found in all cbl defects except for cblB and cblD-MMA; cblC was the most frequent disorder affecting 137 (84.0%) patients. The c.271dupA was the most common pathogenic variant, accounting for 70/105 (66.7%) cases. One hundred and thirty-seven out of 154 (88.9%) patients presented with early-onset disease (0-12 months). Nystagmus and strabismus were observed in all groups with the exception of MMA patients while maculopathy and peripheral retinal degeneration were almost exclusively found in MMA-HCU patients. Optic nerve damage ranging from mild temporal disc pallor to complete atrophy was prevalent in MMA-HCU.and MMA groups. Nystagmus was frequent in early-onset patients. Retinal and macular degeneration worsened despite early treatment and stabilized systemic function in these patients. The functional prognosis remains poor with final visual acuity < 20/200 in 55.6% (25/45) of cases. In conclusion, the spectrum of eye disease in Cbl patients depends on metabolic severity and age of onset. The development of visual manifestations over time despite early metabolic treatment point out the need for specific innovative therapies.

Development of Nystagmus With the Absence of MYOD Expression in the Extraocular Muscles

Purpose

Myoblast determination protein 1 (MYOD) is a critical myogenic regulatory factor in muscle development, differentiation, myofiber repair, and regeneration. As the extraocular muscles significantly remodel their myofibers throughout life compared with limb skeletal muscles, we hypothesized that the absence of MYOD would result in their abnormal structure and function. To assess structural and functional changes in the extraocular muscles in MyoD-/- mice, fiber size and number and optokinetic nystagmus reflex (OKN) responses were examined.

Methods

OKN was measured in MyoD-/- mice and littermate wild-type controls at 3, 6, and 12 months. The extraocular muscles were examined histologically for changes in mean myofiber cross-sectional area, total myofiber number, and nuclei immunostained for PAX7 and PITX2, markers of myogenic precursor cells.

Results

The MyoD-/- mice developed nystagmus, with both jerk and pendular waveforms, in the absence and in the presence of moving visual stimulation. At 12 months, there were significant losses in mean myofiber cross-sectional area and in total number of orbital layer fibers in all rectus muscles, as well as in global layer fibers in the superior and inferior rectus muscles. Haploinsufficient mice showed abnormal OKN responses. PITX2-positive cell entry into myofibers of the MyoD-/- mice was significantly reduced.

Conclusions

This study is the first demonstration of the development of nystagmus in the constitutive absence of expression of the muscle-specific transcription factor MYOD. We hypothesize that myofiber loss over time may alter anterograde and/or retrograde communication between the motor nerves and extraocular muscles that are critical for maintaining normalcy of extraocular muscle function.

Diagnostic yield of targeted next-generation sequencing in infantile nystagmus syndrome

Background: Infantile nystagmus syndrome (INS) is a genetically heterogeneous disorder. Identifying genetic causes of INS would help clinicians to facilitate clinical diagnosis and provide appropriate treatment. The aim of this study was to determine the diagnostic utility of targeted next-generation sequencing (NGS) for INS.Materials and methods: We recruited 37 patients who were referred to the Neuro-ophthalmology clinics for evaluations of INS. NGS was performed using a targeted panel that included 98 candidate genes associated with INS. We identified pathogenic variants according to guidelines of the American College of Medical Genetics and Genomics. We also calculated the sensitivity and specificity of each clinical sign to assess the diagnostic yield of our gene panel.Results: After variant filtering, annotation, and interpretation, the potential pathogenic variants were detected in 13 of the 37 patients, achieving a molecular diagnostic rate of 35%. The identified genes were PAX6 (n = 4), FRMD7 (n = 4), GPR143 (n = 2), CACNA1F (n = 1), CNGA3 (n = 1) and GUCY2D (n = 1). In approximately 30% (n = 4) of the patients, the initial clinical diagnosis was revised after a molecular diagnosis was performed. The presence of a family history had the highest predictive power for a molecular diagnosis (sensitivity = 61.5%, specificity = 91.7%), and the sensitivity increased when the family history was considered together with one of two clinical signs such as pendular nystagmus waveforms or anterior segment dysgenesis.Conclusions: Our study shows that targeted NGS can be useful to determine a molecular diagnosis for patients with INS. Targeted NGS also helps to confirm a clinical diagnosis in atypical phenotypes or unresolved cases.

TUBB3 M323V Syndrome Presents with Infantile Nystagmus

Variants in the TUBB3 gene, one of the tubulin-encoding genes, are known to cause congenital fibrosis of the extraocular muscles type 3 and/or malformations of cortical development. Herein, we report a case of a 6-month-old infant with c.967A>G:p.(M323V) variant in the TUBB3 gene, who had only infantile nystagmus without other ophthalmological abnormalities. Subsequent brain magnetic resonance imaging (MRI) revealed cortical dysplasia. Neurological examinations did not reveal gross or fine motor delay, which are inconsistent with the clinical characteristics of patients with the M323V syndrome reported so far. A protein modeling showed that the M323V mutation in the TUBB3 gene interferes with αβ heterodimer formation with the TUBA1A gene. This report emphasizes the importance of considering TUBB3 and TUBA1A tubulinopathy in infantile nystagmus. A brain MRI should also be considered for these patients, although in the absence of other neurologic signs or symptoms.

Genetic causes of nystagmus, foveal hypoplasia and subnormal visual acuity- other than albinism

Background: To describe genetic molecular findings in individuals with congenital nystagmus, foveal hypoplasia, and subnormal vision, with normal ocular pigmentation (absence of diffuse transillumination or transparent retinal pigment typical for albinism).Methods: This is a retrospective, multicenter study of ophthalmic, systemic, and genetic features, as collected from medical records of patients diagnosed with infantile nystagmus and foveal hypoplasia. Ophthalmic findings include best-corrected visual acuity (BCVA), biomicroscopic examination, cycloplegic refraction, retinal examination, macular optical coherence tomography, and electroretinography. Genetic information was retrieved from the participating genetic clinics and included ethnicity and molecular diagnosis.Results: Thirty-one individuals met the inclusion criteria and had a secure molecular diagnosis. Mutations in two genes predominated, constituting 77.4% of all the represented genes: SLC38A8 (45.1%) and PAX6 (32.3%). Seventy-eight percent of the subjects who had a measurable BCVA had moderate and severe visual impairment (range 20/80 to 20/270). Most patients with a mutation in SLC38A8 had mild to moderate astigmatism, while most patients with PAX6 mutation had moderate and severe myopia. Patients in the PAX6 group had variable degrees of anterior segment manifestations.Conclusion: In our cohort, the main causative genes for congenital nystagmus and foveal hypoplasia in normally pigmented eyes were SLC38A8 and PAX6. A mild phenotype in PAX6 mutations may be an under-diagnosed cause of nystagmus and foveal hypoplasia. Reaching an accurate genetic diagnosis is essential for both the patients and their family members. This enables predicting disease prognosis, tailoring correct follow-up, and providing genetic counseling and family planning to affected families.

Post audio-visual biofeedback training visual functions and quality of life in paediatric idiopathic infantile nystagmus: A pilot study

Purpose:

Biofeedback training (BT) was adapted to idiopathic infantile nystagmus syndrome (IINS) cases to enhance visual functions and quality of life (QoL).

Methods:

10 patients (age 9 ± 3.2 years) treated with the audio-visual BT module of the MAIA microperimeter (Centervue, Padova, Italy) were assessed in two baseline visits and 1week post-BT (BT 80 min in total). The outcomes were distance and near binocular best corrected visual acuity (BBCVA), fixation stability, reading speed, contrast sensitivity, stereopsis and Children’s Visual Function Questionnaire. One-way repeated measured ANOVA and paired t-tests were used.

Results:

Distance BBCVA improved from 0.46 ± 0.21 and 0.43 ± 0.18 pre-BT to 0.33 ± 0.2 logMAR post-BT (F (2,27) = 13.75, p = 0.0002). Post-BT was better than baseline (p = 0.0001) and pre-BT (p = 0.001). Near BBCVA improved from 0.23 ± 0.09 and 0.21 ± 0.14 pre-BT to 0.04 ± 0.08 post-BT (F (2,27) = 22.12, p = 0.000014), post-BT was better than baseline (p = 0.0001) and pre-BT (p = 0.0006). Stereopsis improved from 283 ± 338″ to 39 ± 32.2″ (p = 0.04), contrast sensitivity from 0.26 ± 0.17 to 0.08 ± 0.12 log units (p = 0.01), and reading speed improved from 74.7 ± 51.2 wpm to 104.7 ± 53.6 wpm (p = 0.0006). Fixation stability improved from 33.6 ± 28.1 to 14.3 ± 10.1 sq. QoL increased from 23.8 ± 2.2 to 26.3 ± 2.3 units (p = 0.001).

Conclusion:

BT benefited all visual functions and QoL in this pilot study, heralding a new possibility for Low Vision Rehabilitation in IINS.

Congenital ocular malformations in dogs and cats: 123 cases

OBJECTIVE

Provide epidemiological data regarding the prevalence of congenital ocular malformations in dogs and cats.

ANIMALS STUDIED

A population of 32 974 dogs and 13 977 cats that presented for consultation at the veterinary teaching hospital.

PROCEDURES

Medical records from 2011 to 2018 were reviewed. A retrospective and prospective epidemiological clinical study addressing congenital ocular malformations was conducted. Signalment, medical history, reason for presentation, clinical findings, vision impairment, and treatment options were analyzed.

RESULTS

From the total of cases analyzed, 103 dogs (0.3%) and 20 cats (0.1%) met the inclusion criteria. The majority of dogs were mixed breed, the most common breed being the French Bulldog, while the majority of cats were European domestic shorthair. The median age of diagnosis was 12 months for dogs and 6 months for cats. Sex predisposition was not found. The most frequently identified abnormalities were as follows: congenital cataract (dogs: 31.1%; cats: 30.0%), microphthalmia (dogs: 35.0%, cats: 25.0%), and persistent pupillary membrane (dogs: 27.2%, cats: 40.0%). Some of the concurrently observed malformations were significantly associated. A statistically significant association was found between ocular dermoids and the French Bulldog breed (P < .001).

CONCLUSIONS

Even though congenital ocular malformations are uncommon, knowledge about their prevalence is important, since they can cause vision impairment or even blindness. Moreover, some human ocular disease phenotypes are similar to the ones presented by dogs and cats, so they can be used as models to investigate pathophysiology and therapeutic approaches.

Ocular evaluation and genetic test for an early Alström Syndrome diagnosis

Purpose

We present 3 cases of Alström syndrome (ALMS) that highlight the importance of the ophthalmic exam, as well as the diagnostic challenges and management considerations of this ultra-rare disease.

Observations

The first case is of a 2-year-old boy with history of spasmus nutans who presented with head bobbing and nystagmus. The second patient is a 5-year-old boy with history of infantile dilated cardiomyopathy status post heart transplant, Burkitt lymphoma status post chemotherapy, obesity, global developmental delay, and high hyperopia previously thought to have cortical visual impairment secondary to heart surgery/possible ischemic event. This patient presented with nystagmus, photophobia, and reduced vision. The third case involves a 8-year-old boy with history of obesity, bilateral optic nerve atrophy, hyperopic astigmatism, exotropia, and nystagmus. Upon presentation to the consulting pediatric ophthalmologist, none of the patients had yet been diagnosed with ALMS. All 3 cases were subsequently found to have an electroretinogram (ERG) that exhibited severe global depression and to carry ALMS1 pathogenic variants.

Conclusions and Importance

ALMS is an autosomal recessive disease caused by ALMS1 variations, characterized by cone-rod dystrophy, obesity, progressive sensorineural hearing loss, cardiomyopathy, insulin resistance, and multiorgan dysfunction. Retinal dystrophy diagnosis is critical given clinical criteria and detection rates of genetic testing. Early diagnosis is extremely important because progression to flat ERG leads to the inability to differentiate between rod-cone or cone-rod involvement, either of which have their own differential diagnoses. In our series, the ophthalmic exam and abnormal ERG prompted further genetic testing and the subsequent diagnosis of ALMS. Multidisciplinary care ensures the best possible outcome with the ophthalmologist playing a key role.

Prevalence and causes of infantile nystagmus in a large population-based Danish cohort

PURPOSE

The aim of this study was to provide a population-based estimate on the prevalence of infantile nystagmus and to describe the causes in the Capital Region of Denmark.

METHODS

Review of medical records of children with infantile nystagmus born in the period 1 January 2010 through 31 December 2017 and living in the Capital Region of Denmark. We used birth registry data from Statistics Denmark and the National Danish Birth Registry to calculate the prevalence of nystagmus in children born at term and prematurely.

RESULTS

A total of 103 patients (52 males/51 females) with infantile nystagmus were included. The overall prevalence of infantile nystagmus was 6.1 per 10 000 live births. It was higher in premature children (28.4/10 000 live births) than children born at term (4.4/10 000), p < 0.0001, and highest in children born extremely preterm, (97.3/10 000). The most common cause of infantile nystagmus was ocular disease (44%) followed by idiopathic nystagmus (32%), neurological disorders and genetic syndromes (20%) and prematurity without retinopathy of prematurity as the only cause (4%).

CONCLUSIONS

In this study, we provide the prevalence of infantile nystagmus based on national medical records in which all residents are accounted for. Our findings show a prevalence of 6.1 per 10 000 live births but six times higher among children born preterm than born at term. Ocular disease was the leading cause of infantile nystagmus with albinism and ocular malformations as the most frequent. In 1/3 of patients, no cause could be identified.

Congenital Nystagmus and Its Congeners

In recent years, we have made enormous strides in elucidating the phenomenology of congenital nystagmus. The purpose of this review is to briefly summarize our current understanding of congenital nystagmus in terms of its clinical symptomatology, pathophysiology, differential diagnosis, and ancillary testing, and clinical management. Finally, this discussion provides the reader with an armamentarium of clinical pearls to facilitate diagnosis of the numerous sensory visual disorders that can underlie congenital nystagmus.

Nystagmus and optical coherence tomography findings in CNGB3-associated achromatopsia

PURPOSE

To describe the nystagmus characteristics of subjects with molecularly confirmed CNGB3-associated achromatopsia and report the spectral domain optical coherence tomography (SD-OCT) findings in these individuals.

METHODS

Adults and children with CNGB3-achromatopsia underwent visual acuity testing, ocular motility assessments, video nystagmography, and SD-OCT imaging. Qualitative assessment of foveal structure was performed by grading SD-OCT images into one of five categories.

RESULTS

A total of 18 subjects (11 adults) were included. The majority demonstrated a phoria, with manifest strabismus present in only 3 subjects. The predominant nystagmus waveform within the cohort was pure pendular. Nine individuals demonstrated a mixture of waveforms. Nystagmus frequencies were 4-8 cycles/second, with no notable differences in eye movements between adults and children. SD-OCT imaging revealed a continuous ellipsoid zone (EZ) at the fovea in 2 subjects (grade 1) and EZ disruption (grade 2) in the remaining 16. Retinal structure characteristics were symmetrical in both eyes in each subject.

CONCLUSIONS

In our study cohort, nystagmus in CNGB3-associated achromatopsia had distinctive features, and the majority of subjects had retinal abnormalities at the fovea on SD-OCT. Early use of SD-OCT in the clinical work-up may eliminate the need for more invasive investigations, such as neuro-imaging.

Survey of practice patterns for the management of ophthalmic genetic disorders among AAPOS members: report by the AAPOS Genetic Eye Disease Task Force

To better understand AAPOS member pediatric ophthalmologists' knowledge and needs regarding genetic eye disorders, the AAPOS Genetic Eye Disease Task Force developed a 16-question survey that was circulated to national and international AAPOS members. Responses to questions on practice patterns, baseline knowledge, and educational interests regarding patients with suspected ophthalmic genetic disorders were collected. A majority of respondents (93%) evaluate patients with suspected genetic disorders. Knowledge gaps were present in heritability of certain conditions, genetic testing strategies, and referral to clinical trials. Most respondents expressed interest in further education in these areas. A model for care is proposed as a first step in the education process.

High-dose Anderson operation for nystagmus-related anomalous head turn

PURPOSE

To evaluate the effectiveness of a high-dose Anderson procedure (AP) to correct infantile nystagmus-related anomalous head turn (HT).

METHODS

Twenty-nine consecutive orthotropes with infantile nystagmus with and without associated sensory defect received high-dose AP. HT was measured while the patient tried to read letters at best-corrected visual acuity (BCVA) level at 5 m and 0.3 m. BCVA, binocular vision (BV), and alignment (prism and cover test) were measured. High-dose AP with recessions of 9-16 mm was performed. All measures were taken before and 3-6 and ≥ 8 months post surgery. Success was defined by postoperative HT ≤ 10°/HT ≤ 15°.

RESULTS

Medians and ranges (minimum-maximum) were:. Age at surgery was 7 years (4-44). HT at 5 m and HT at 0.3 m were 35° (20-40) and 20° (0-35), respectively. After 4 months (3-6), HT was 10° (- 3-20) and 5° (- 5-20); success rates were 74%/96% and 83%/96%. After 15 months (8-45), HT was 12° (0-20) and 6° (0-15); success rates were 46%/75% and 92%/100%; residual HT > 15° occurred in 5/9 cases with recessions < 13 mm and 1/15 cases with recessions ≥ 13 mm. With recessions ≥ 13 mm, 60% (95% confidence intervals (C.I.), 33-83%) achieved HT ≤ 10° and 93% (95% C.I. 66-99%) achieved HT ≤ 15°. Overcorrection did not occur. Anomalous head posture components in vertical and frontal planes did not improve. Residual motility was 30° (10-45). The mean BCVA improved by only 0.037 logMAR (p = 0.06). BV and ocular alignment were constant, except in 2 patients whose exophoria decompensated.

CONCLUSIONS

Kestenbaum surgery is a common procedure to correct infantile nystagmus-related HT. Anderson surgery is confined to bilateral yoke muscle recession; hence, less invasive but nevertheless comparably effective, high dosage is provided.

Comparison of Optic Canal Diameter in Children With Malignant Infantile Osteopetrosis and Normal Children and the Effects of Hematopoietic Stem Cell Transplantation on the Optic Canal Diameter

PURPOSE

To investigate the difference in the optic canal diameter between children with autosomal recessive malignant infantile osteopetrosis and normal children, and to assess the influence of hematopoietic stem cell transplantation on the optic canal diameter.

METHODS

Twenty pediatric patients with malignant infantile osteopetrosis and 22 normal control children were included in this study. Eleven patients with malignant infantile osteopetrosis underwent hematopoietic stem cell transplantation. The measurements included optical canal diameter and flash visual evoked potential. Comparisons of these measurements between patients with malignant infantile osteopetrosis and normal controls as well as before and after hematopoietic stem cell transplantation were performed. The correlation between age and optic canal diameter was analyzed using Pearson correlation analysis.

RESULTS

The mean optic canal diameter before hematopoietic stem cell transplantation was 1.65 ± 0.54 mm in patients with malignant infantile osteopetrosis and 3.38 ± 0.60 mm in the control group (P < .001). The mean optic canal diameter after hematopoietic stem cell transplantation was 2.72 ± 0.66 mm, which was significantly different from the pre-transplantation measurement (P < .001). The P2 latency for the flash visual evoked potential after hematopoietic stem cell transplantation (152.3 ± 36.4 ms) was significantly less than that before transplantation (165.5 ± 27.7 ms; P = .051). Pearson correlation analysis revealed a significant correlation between age and optic canal diameter (r = 0.722, P < .001).

CONCLUSIONS

The optic canal was narrower in pediatric patients with malignant infantile osteopetrosis than in age-matched normal controls. This condition can be relieved through hematopoietic stem cell transplantation and the impaired conductibility of the optic nerve can be improved in some cases. [J Pediatr Ophthalmol Strabismus. 2019;56(1):35-42.].

[Etiological assessment of a nystagmus in childhood]

Apart from the latent nystagmus, which arises as a consequence of failure to develop binocular vision, every case of childhood nystagmus needs an etiological assessment. Knowledge of the pathogenesis of the various types of nystagmus guides this assessment, particularly considering the morphological characteristics of the nystagmus. The clinical ophthalmologic examination is complemented by OCT and electrophysiologic testing (ERG, VEP). If this testing is normal, an MRI and genetic assessment are required.

Dealing with Nystagmus

Nystagmus has a profound impact on patients visual function and social life. Infantile nystagmus (IN) is much more common than neurological nystagmus, and establishing the correct diagnosis is key in guiding the appropriate treatment paradigm. This paper attempts to demonstrate a stepwise approach in investigation and clinical evaluation, that is (often) sufficient in differentiating IN from nystagmus of neurological origin, and to uncover underlying sensory etiologies of IN. Targeted and rational uses of paraclinical exams are emphasized when they deemed necessary to complement the clinical assessment. The author's preferred surgical and non-surgical strategies to optimize vision, and improve the head posture and strabismus that can accompany nystagmus, are discussed (although without the goal of writing a complete revision on the topic).

Presentation of TRPM1-Associated Congenital Stationary Night Blindness in Children

IMPORTANCE

Congenital stationary night blindness (CSNB) implies a stable condition, with the major symptom being nyctalopia present at birth. Pediatric clinical presentation and the course of different genetic subtypes of CSNB have not, to our knowledge, been well described in the era of molecular genetic diagnosis.

OBJECTIVE

To describe the presentation and longitudinal clinical characteristics of pediatric patients with molecularly confirmed TRPM1-associated complete CSNB (cCSNB).

DESIGN, SETTING, PARTICIPANTS

This study was conducted at the University of Iowa from January 1, 1990, to July 1, 2015, and was a retrospective, longitudinal case series of 7 children (5 [71.4%] female) with TRPM1-associated cCSNB followed up for a mean (SD) of 11.1 (2.8) years.

MAIN OUTCOMES AND MEASURES

History, ophthalmologic examination findings, full-field electroretinogram (ffERG) results, full-field stimulus threshold testing results, Goldmann visual field results, optical coherence tomography results, and molecular genetic results were evaluated. Presenting symptoms and signs, the correlation of refractive error with electroretinography, and clinical evolution were analyzed.

RESULTS

Seven patients (5 [71.4%] female) presented early in childhood with strabismus (n = 6 [86%]), myopia (n = 5 [71%]), and/or nystagmus (n = 3 [43%]). The mean (SD) age at presentation was 8 (4) months and for receiving a diagnosis by ffERG was 7.3 years, with molecular diagnosis at 9.7 years. The mean (SD) length of follow-up was 11 (2.8) years. The best-corrected visual acuity at the most recent visit averaged 20/30 in the better-seeing eye (range, 20/20-20/60). The mean (SD) initial refraction was -2.80 (4.42) diopters (D) and the mean refraction at the most recent visit was -8.75 (3.53) D (range, -4.00 to -13.75 D), with the greatest rate of myopic shift before age 5 years. Full-field electroretinogram results were electronegative, consistent with cCSNB, without a significant change in amplitude over time. No patient or parent noted night blindness at presentation; however, subjective nyctalopia was eventually reported in 5 of 7 patients (71%). The full-field stimulus threshold testing results were moderately subnormal (-29.7 [3.8] dB; normal -59.8 [4.0] dB). Goldmann visual field results were significant for full I-4e, but constricted I-2e isopter. Eight different mutations or rare variants in TRPM1 predicted to be pathogenic were detected, with 3 novel variants.

CONCLUSIONS AND RELEVANCE

Children with TRPM1-associated cCSNB presented before school age with progressive myopia as well as strabismus and nystagmus (but not nyctalopia), with stable, electronegative ffERG results, mildly subnormal full-field stimulus threshold testing results, and a constricted I2e isopter on perimetry. These findings suggest that ffERG and cCSNB genetic testing should be considered for children who present with early-onset myopia, especially in the presence of strabismus and/or nystagmus, and that TRPM1-associated cCSNB is a channelopathy that may present without complaints of night blindness in childhood.