Refractive and Vision Status in Down Syndrome: A Comparative Study

Prevalence and Etiology of Strabismus in Down Syndrome: A Systematic Review and Meta-Analysis with a Focus on Ethnic Differences in the Esotropia/Exotropia Ratio

PURPOSE

We sought to determine the prevalence of strabismus and the esotropia/exotropia ratio in Down syndrome. Wide ranges of an increased strabismus prevalence have been reported and it is unclear by how much esotropia exceeds exotropia in people with Down syndrome.

METHODS

We compiled in a systematic review and meta-analysis results of over 100 studies that report the strabismus prevalence and ratio of esotropia/exotropia in cohorts of Down syndrome. We calculated the pooled global prevalence and established the geographical distribution of the strabismus prevalence and the esotropia/exotropia ratio.

RESULTS

The ethnically-adjusted global prevalence of strabismus in Down syndrome is 30.2%. In subjects 15 years and older, the global prevalence is 53.2%, and the lifetime prevalence is 51.0%. In populations which normally have more esotropia than exotropia (e.g. Caucasians), Down syndrome subjects have a further increased bias towards esotropia. In populations which normally have more exotropia (e.g. West Africans, Asians and Hispanics), Down syndrome subjects have a significantly lower esotropia/exotropia ratio (3.21) than reported in Caucasians with Down syndrome (9.98).

CONCLUSION

Worldwide, about 1.81 million people with Down syndrome have strabismus: 1.42 million of them have esotropia, and 0.37 million have exotropia. Differences in the esotropia/exotropia ratio between ethnicities point to the orbital anatomy as a major contributing factor to the etiology of strabismus in Down syndrome. The narrow-set eyes (reduced orbital width) in Down syndrome favor esotropia over exotropia, especially in Caucasians, thus explaining why Down syndrome patients from different ethnicities have different prevalences of esotropia and exotropia.

The Ocular Manifestations of Individuals With Down Syndrome: A Systematic Review and Meta-Analysis

Background: Down syndrome (DS) is the most common genetic cause of intellectual disability. Ocular manifestations occur frequently in people with DS (pwDS) but to date, there is no systematic review or meta-analysis of these conditions across the lifespan. Methods: PubMed, Medline, Embase, Web of Science and Scopus were searched for observational studies reporting ocular manifestations in pwDS, without limiting publication date. The proportion of pwDS with specific ocular manifestations were meta-analysed to obtain a pooled incidence using a random effects model. Sources of heterogeneity were assessed using a meta-regression analysis. For manifestations reported, but without sufficient prevalence data available, a narrative approach was adopted. Results: The search identified 1208 papers. Reviewers independently screened the abstracts, and 54 studies were found to fit the criteria. The age range of the individuals was birth to 88.7 years. Ocular manifestations from highest to lowest prevalence included refractive errors (69.97%, 95% CI 59.95%-79.13%), strabismus (31.41%, 95% CI 24.66%-38.57%), lens opacities (13.79%, 95% CI 8.61%-19.86%), nystagmus (12.72%, 95% CI 9.02%-16.92%) and keratoconus (9.34%, 95% CI 2.47%-19.26%). Alterations of lens and corneal morphology, posterior segment anomalies (including glaucoma) and Brushfield spots were also identified. Conclusions: The ocular manifestations of pwDS are common but varied. Age and/or ethnicity may influence the prevalence of certain ocular manifestations. The level of intellectual disability may also affect the prevalence of ocular manifestations as the prevalence of ocular disorders is known to increase with the severity of intellectual disability in pwDS.

Corneal Collagen Cross-linking for Keratoconus in Pediatric and Developmentally Delayed Patients

PURPOSE

Corneal cross-linking (CXL) is the standard of care in patients with keratoconus but presents unique challenges in children and developmentally delayed patients. We present our clinical decision-making algorithm, CXL surgical technique, and outcomes in these groups.

METHODS

A retrospective chart review was undertaken at a tertiary referral center of all patients who underwent CXL for keratoconus at University of Pittsburgh Medical Center (UPMC) Children's Hospital of Pittsburgh between October 1, 2017, and April 1, 2021. Demographic information along with preoperative, intraoperative, and postoperative ophthalmic examination findings were collected. The main outcome measures were indications of CXL, postoperative complications, and visual acuity (VA).

RESULTS

Forty-eight eyes of 34 patients [21 patients (30 eyes) with developmental delay (DD) and 13 patients (18 eyes) with no DD (NDD)] underwent epithelium-off, standard CXL. General anesthesia was used for CXL in all patients except for 3 with NDD. A temporary central tarsorrhaphy was performed in all patients with DD and 7 patients with NDD. The remaining got a bandage contact lens. There were no immediate postoperative complications. A trend toward improvement in VA was noted postoperatively. The mean logMAR VA (with habitual correction) was 0.67 preoperatively and 0.57 postoperatively ( P = 0.3) in DD and 0.52 and 0.36, respectively ( P = 0.13), in NDD.

CONCLUSIONS

This retrospective review presents a technique for assessment and treatment of keratoconus in children and those with DD. Our technique ensures timely diagnosis and provides a safe method for CXL in these groups. Temporary central tarsorrhaphy is a well-tolerated option to reduce postoperative pain.

Prevalence and etiology of strabismus in Down syndrome: A systematic review and meta-analysis with a focus on ethnic differences in the esotropia/exotropia ratio

Purpose

We sought to determine the prevalence of strabismus and the esotropia/exotropia ratio in Down syndrome. Wide ranges of an increased strabismus prevalence have been reported and it is unclear by how much esotropia exceeds exotropia in people with Down syndrome.

Methods

We compiled in a systematic review and meta-analysis the results of over 100 studies that report the strabismus prevalence and ratio of esotropia/exotropia in cohorts of Down syndrome. We calculated the pooled global prevalence and established the geographical distribution of the strabismus prevalence and the esotropia/exotropia ratio.

Results

The ethnically-adjusted global prevalence of strabismus in Down syndrome is 30.2%. In subjects 15 years and older, the global prevalence is 53.2%, and the lifetime prevalence is 51.0%. In populations which normally have more esotropia than exotropia (e.g., Caucasians), Down syndrome subjects have a further increased bias towards esotropia. In populations which normally have more exotropia (e.g., West Africans, Asians and Hispanics), Down syndrome subjects have a significantly lower esotropia/exotropia ratio (3.21) than reported in Caucasians with Down syndrome (9.98).

Conclusion

Worldwide, about 1.81 million people with Down syndrome have strabismus: 1.42 million of them have esotropia, and 0.37 million have exotropia. Differences in the esotropia/exotropia ratio between ethnicities point to the orbital anatomy as a major contributing factor to the etiology of strabismus in Down syndrome. The narrow-set eyes (reduced orbital width) in Down syndrome favor esotropia over exotropia, especially in Caucasians, thus explaining why Down syndrome patients from different ethnicities have different prevalences of esotropia and exotropia.

Retinoscopes: Past and present

BACKGROUND

Retinoscopy is arguably the most important method in the eye clinic for diagnosing and managing refractive errors. Advantages of retinoscopy include its non-invasive nature, ability to assess patients of all ages, and usefulness in patients with limited cooperation or communication skills.

AIM

To discuss the history of retinoscopes and examine current literature on the subject.

METHODS

A search was conducted on the PubMed and with the reference citation analysis (https://www.referencecitationanalysis.com) database using the term "Retinoscopy," with a range restricted to the last 10 years (2013-2023). The search string algorithm was: "Retinoscopy" (MeSH Terms) OR "Retinoscopy" (All Fields) OR "Retinoscopes" (All Fields) AND [(All Fields) AND 2013: 2023 (pdat)].

RESULTS

This systematic review included a total of 286 records. Publications reviewed iterations of the retinoscope into autorefractors, infrared photo retinoscope, television retinoscopy, and the Wifi enabled digital retinoscope.

CONCLUSION

The retinoscope has evolved significantly since its discovery, with a significant improvement in its diagnostic capabilities. While it has advantages such as non-invasiveness and broad applicability, limitations exist, and the need for skilled interpretation remains. With ongoing research, including the integration of artificial intelligence, retinoscopy is expected to continue advancing and playing a vital role in eye care.

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.

Cognitive outcome measures for tracking Alzheimer's disease in Down syndrome

Down syndrome (DS) is now viewed as a genetic type of Alzheimer's disease (AD), given the near-universal presence of AD pathology in middle adulthood and the elevated risk for developing clinical AD in DS. As the field of DS prepares for AD clinical intervention trials, there is a strong need to identify cognitive measures that are specific and sensitive to the transition from being cognitively stable to the prodromal (e.g., Mild Cognitive Impairment-Down syndrome) and clinical AD (e.g., Dementia) stages of the disease in DS. It is also important to determine cognitive measures that map onto biomarkers of early AD pathology during the transition from the preclinical to the prodromal stage of the disease, as this transition period is likely to be targeted and tracked in AD clinical trials. The present chapter discusses the current state of research on cognitive measures that could be used to screen/select study participants and as potential outcome measures in future AD clinical trials with adults with DS. In this chapter, we also identify key challenges that need to be overcome and questions that need to be addressed by the DS field as it prepares for AD clinical trials in the coming years.

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).