Ophthalmic manifestations in children and young adults with Down syndrome and congenital heart defects

Ophthalmologic and neuro-ophthalmologic findings in children with Down syndrome

Down syndrome, also known as Trisomy 21, is a genetic disorder associated with mild-to-moderate intellectual disability, delays in growth, and characteristic facial features. A wide range of ocular complications are seen in children with Down syndrome, including strabismus, nystagmus, refractive errors, congenital cataracts, the presence of keratoconus, and decreased visual acuity. Early ophthalmic examination is needed for early diagnosis and treatment in patients. This narrative review examines ocular manifestations in children with Down syndrome and the importance of prompt ophthalmic interventions for treatment.

The Ophthalmic Manifestations of Down Syndrome

Down Syndrome is one of the most common chromosomal conditions in the world, affecting an estimated 1:400-1:500 births. It is a multisystem genetic disorder but has a wide range of ophthalmic findings. These include strabismus, amblyopia, accommodation defects, refractive error, eyelid abnormalities, nasolacrimal duct obstruction, nystagmus, keratoconus, cataracts, retinal abnormalities, optic nerve abnormalities, and glaucoma. These ophthalmic conditions are more prevalent in children with Down Syndrome than the general pediatric population, and without exception, early identification with thoughtful screening in this patient population can drastically improve prognosis and/or quality of life.

Conventional surgery versus botulinum toxin injection for the management of esotropia in children with Down syndrome

PURPOSE

To compare the success rates of strabismus surgery and botulinum toxin injection (BTX) in treating esotropia in patients with Down syndrome (DS).

METHODS

This multicenter retrospective cohort study included all consecutive patients having DS with esotropia between 2014 and 2021 at King Abdullah Specialist Children Hospital, King Abdullah International Medical Research Center, and King Khaled Eye Specialist Hospital, Saudi Arabia. We divided the patients into two groups according to interventions. Success was defined as angle of deviation of <10^Δ at final visit.

RESULTS

A total of 53 patients were included: 23 in the surgery group and 30 in the BTX group. There were no significant differences between groups with regard to age, sex, diagnosis, spherical equivalent, and preoperative deviation angle. Before the intervention, the median angle of deviation was 30.0^Δ (IQR, 30^Δ-45^Δ) in the surgery group and 37.5^Δ (IQR, 28.8^Δ-50.0^Δ) in the BTX group (P = 0.802). Postoperatively, the median (IQR) deviation angle was 0.0^Δ (0.0^Δ-16.0^Δ) in the surgery group and 22.5^Δ (6.75^Δ-30.0^Δ) in the BTX group (P = 0.006). The success rate in the surgery and BTX groups was 65% and 30%, respectively (P = 0.011). Two patients developed dissociated vertical deviation in the surgery group. One patient presented consecutive exotropia and one inferior oblique overaction in the BTX group.

CONCLUSIONS

In this study, conventional surgery showed a higher success rate than BTX in the management of esotropia.

Status of Visual Impairment among Children with Special Needs in Rural China

INTRODUCTION

Previous studies have reported a high prevalence of visual defects in children with special needs. However, routine ocular examinations for these children in rural areas of China are lacking. This study aimed to evaluate the status of visual impairment (VI) in children at special education schools in rural China.

METHODS

A total of 316 students from two special schools in Zunyi city, Guizhou province, were enrolled. Full ophthalmic examinations were performed, and gene-sequencing services were offered to potential patients.

RESULTS

The mean age of the 316 participants was 12.27 ± 3.49 years and 75 showed abnormal ophthalmic manifestations on slit-lamp examination. Visual acuity (VA) was assessed in 232 eyes, and the mean VA (logarithm of the minimum angle of resolution, logMAR) was 0.27 ± 0.34. Whole-exome sequencing identified 19 mutations in these children, which might explain their visual complaints. Children with Down syndrome had a significantly higher prevalence of ocular disorders than those without.

CONCLUSION

VI is common among children at special education schools in rural areas; however, routine screening and effective interventions have not been consistently implemented. Efforts should be made to address this issue in these already disadvantaged children.

Systemic and Ophthalmic Manifestations in Different Types of Refractive Errors in Patients with Down Syndrome

Background and Objective: This study aims to investigate the prevalence of systemic and ophthalmic manifestations in different refractive groups in children and young adults with Down syndrome (DS). Materials and Methods: The study was a population-based, cross-sectional study that included 141 Caucasian children and young adults with DS. They were classified into the following three groups: myopia DS group (37 subjects, mean age 15.8 years), emmetropia DS group (41 subjects, mean age 11.7 years) and hyperopia DS group (63 subjects, mean age 10.9 years). The participants underwent inspection, slit-lamp examination, cycloplegic refraction, ocular alignment and ocular motility examination. Ten systemic manifestations were analyzed. Results: There was no difference in the prevalence of any systemic manifestations between the groups. Considering the ophthalmic manifestations, there was statistical difference in the distribution of proportions among the three groups for nystagmus (p = 0.011), iris-stromal atrophy (p = 0.048) and strabismus (p = 0.031). The prevalence of strabismus in our DS myopia group was 35.1%, and in DS hyperopia group 38.1%. Conclusions: The results of our study suggest that DS children and young adults with any refractive error do not have a higher chance of additional systemic manifestations. Myopia in DS was associated with a higher prevalence of nystagmus and iris stromal atrophy, whereas astigmatism was found to be more frequent in hyperopia.

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.

Neuro-Ophthalmological Manifestations in Children with Down Syndrome: Current Perspectives

Down syndrome, caused by an extra copy of all or part of chromosome 21, is the most prevalent intellectual disability of genetic origin. Among numerous comorbidities which are part of the phenotype of individuals with Down syndrome, ocular problems appear to be highly prevalent. Neuro-ophthalmological manifestations, such as ocular alignment and motility disturbances, amblyopia, hypoaccommodation or optic nerve abnormalities, and other organic ocular anomalies frequently reported in Down syndrome, may lead to an overall decrease in visual acuity. Although numerous studies have reported ocular anomalies related to Down syndrome, it remains challenging to determine the impact of each anomaly upon the decreased visual acuity, as most such individuals have more than one ocular problem. Even in children with Down syndrome and no apparent ocular defect, visual acuity has been found to be reduced compared with typically developing children. Pediatric ophthalmological examination is a critical component of a multidisciplinary approach to prevent and treat ocular complications and improve the visual outcome in children with Down syndrome. This narrative review aims to provide a better understanding of the neuro-ophthalmological manifestations and discuss the current ophthalmological management in children with Down syndrome.

Double-bellied medial rectus muscle in a patient with Down syndrome and congenital esotropia

A 13-year-old male with Down syndrome, pseudophakic secondary to congenital cataract presented with esotropia. During bilateral medial rectus recession, a unilateral two-bellied right medial rectus was identified and recessed successfully with complete resolution of the deviation. Clinicians facing a two-bellied medial rectus can consider continuing with their surgical plan.

Strabismus Surgery for Esotropia, Down Syndrome and Developmental Delay; Is an Altered Surgical Dose Required? A Literature Review

Background and Purpose:

There is a high rate of strabismus, in particular esotropia, in children with Down syndrome or developmental delay, which frequently requires surgical correction. A paper in 1994 advocated that the surgical dose be adjusted due to an altered response in these children. The aim of this literature review is to evaluate the available evidence to establish whether an altered surgical approach is required in either population.

Methods:

A literature review was conducted using PubMed and Web of Knowledge. Only English language papers were eligible for inclusion. The papers were collated in chronological order for analysis, and their references searched for further relevant papers. Forward citation searches were also undertaken.

Results:

A 2 × 2 comparison is made between publications on Down syndrome (in isolation) and developmental delay populations (including Down syndrome) with adjusted versus non-adjusted surgery. Published surgical success rates on esotropia from unaltered surgical doses range from 62.0%–85.7% (four papers) in the Down syndrome cohort, with none of the adjusted surgeries having a successful outcome. Surgical success rates from adjusted surgical doses in developmental delay cohort range from 37.5%–86.0% (seven papers), with one unadjusted surgical success rate of 76.0%. The results across the studies are summarised in a table and discussed.

Conclusions:

An exaggerated surgical effect in individuals with developmental delay has been reported, and this population may benefit from a reduced surgical dose. Published research does not support giving a reduced surgical dose in individuals with Down syndrome, but more research needs to be done to make a definitive conclusion.

Ocular alignment, media, and eyelid disorders in Down syndrome

Background: Determining the age and gender distribution of ocular disorders in Down syndrome patients aged 10 to 30 years.Methods: In this study, 226 of 250 invited patients through special needs schools, the National Down Syndrome Society, and relevant nonprofit organizations were included. In Noor Eye Hospital, the patients underwent a complete eye examination by a general ophthalmologist and suspect cases were reexamined by a sub-specialist. Examinations included ocular alignment, conjunctiva, eyelid, lacrimal system, cornea, iris, and lens assessment.Results: Mean age of participants was 16.05 ± 4.82 years and 53.0% were male. The most common ocular abnormalities were blepharitis (81.9%, 95% CI:78.0 to 85.3), lens opacity (37.8%, 95% CI:33.3 to 42.3), strabismus (23.4%, 95% CI:19.5 to 27.4; 21.2% esotropia, 0.9% exotropia, and 1.8% dissociated vertical deviation), floppy eyelid (19.9%, 95% CI:16.3 to 23.9), posterior embryotoxon (17.7%, 95% CI:14.2 to 21.2) and nystagmus (11.7%, 95% CI:8.9 to 15.0). Based on independent sample t test, the prevalence of nystagmus (P = .041) and congenital lens opacity  (P<0.001) significantly increased with age. There was no significant inter-gender difference in the prevalence of any of the studied disorders by chi-square test.Conclusion: In young patients with Down syndrome, the prevalence of ocular pathologies appears to be high and increase with aging. It can be resulted from the cumulative prevalence of undiagnosed or untreated cases. Findings of the study can be a reliable reference for health policy in terms of screening for eye disease and addressing eye care needs.