Editing Down syndrome (section)

==== Ocular findings ====
[[Brushfield spots]] (small white or grayish/brown spots on the periphery of the [[Iris (anatomy)|iris]]), upward slanting [[palpebral fissure]]s (the opening between the upper and lower lids) and [[Epicanthic folds|epicanthal folds]] (folds of skin between the upper eyelid and the nose) are clinical signs at birth suggesting the diagnosis of Down syndrome<ref name="Wei20102">{{cite journal |vauthors=Weijerman ME, de Winter JP |date=December 2010 |title=Clinical practice. The care of children with Down syndrome |journal=European Journal of Pediatrics |volume=169 |issue=12 |pages=1445–1452 |doi=10.1007/s00431-010-1253-0 |pmc=2962780 |pmid=20632187}}</ref><ref name=":02">{{Cite web |title=Trisomy 21/Down Syndrome - EyeWiki |url=https://eyewiki.org/Trisomy_21/Down_Syndrome#Diagnosis |access-date=2024-05-07 |website=eyewiki.org |language=en}}</ref> especially in the [[Western world|Western World]].<ref name=":02"/>  None of these requires treatment.{{Citation needed|date=May 2024}}

Visually significant congenital [[cataract]]s (clouding of the [[Lens (vertebrate anatomy)|lens]] of the eye) occur more frequently with Down syndrome.<ref name=":02"/> [[Infant|Neonates]] with Down syndrome should be screened for cataract because early recognition and referral reduce the risk of vision loss from [[amblyopia]].<ref name=":13">{{Cite journal |last1=Bull |first1=Marilyn J. |last2=Trotter |first2=Tracy |last3=Santoro |first3=Stephanie L. |last4=Christensen |first4=Celanie |last5=Grout |first5=Randall W. |last6=THE COUNCIL ON GENETICS |date=2022-05-01 |title=Health Supervision for Children and Adolescents With Down Syndrome |url=https://publications.aap.org/pediatrics/article/149/5/e2022057010/186778/Health-Supervision-for-Children-and-Adolescents |journal=Pediatrics |language=en |volume=149 |issue=5 |doi=10.1542/peds.2022-057010 |pmid=35490285 |issn=0031-4005}}</ref>  Dot-like opacities in the cortex of the [[Lens (anatomy)|lens]] (cerulean cataract) are present in up to 50% of people with Down syndrome, but may be followed without treatment if they are not visually significant.<ref name=":02"/>

[[Strabismus]], [[nystagmus]] and [[nasolacrimal duct obstruction]] occur more frequently in children with Down syndrome.<ref name=":02"/>  Screening for these diagnoses should begin within six months of birth.<ref name=":02"/><ref name=":13" />  Strabismus is more often acquired than [[congenital]].<ref name=":02"/>  Early diagnosis and treatment of strabismus reduces the risk of vision loss from amblyopia.<ref name=":63">{{Cite web |title=Strabismus and Amblyopia {{!}} Boston Children's Hospital |url=https://www.childrenshospital.org/conditions/strabismus-and-amblyopia#:~:text=Early%20diagnosis%20is%20essential%20in,the%20eyes%20are%20not%20aligned. |access-date=2024-05-08 |website=www.childrenshospital.org}}</ref>  In Down syndrome, the presence of epicanthal folds may give the false impression of [[strabismus]], referred to as [[pseudostrabismus]]. Nasolacrimal duct obstruction, which causes tearing ([[Epiphora (medicine)|epiphora]]), is more frequently bilateral and multifactorial than in children without Down syndrome.<ref name=":02"/>

[[Refractive error]] is more common with Down syndrome, though the rate may not differ until after twelve months of age compared to children without Down syndrome.<ref name=":02"/> Early screening is recommended to identify and treat significant refractive error with glasses or contact lenses. Poor [[Accommodation reflex|accommodation]] (ability to focus on close objects) is associated with Down syndrome, which may mean bifocals are indicated.<ref name=":02"/>

In [[keratoconus]], the [[cornea]] progressively thins and bulges into a cone shape,<ref name=":23">{{Cite web |title=Keratoconus - Symptoms and causes |url=https://www.mayoclinic.org/diseases-conditions/keratoconus/symptoms-causes/syc-20351352 |access-date=2024-05-08 |website=Mayo Clinic |language=en}}</ref> causing visual blurring or distortion. Keratoconus first presents in the teen years and progresses into the thirties.<ref name=":23" /><ref name=":33">{{Cite web |date=2021-08-08 |title=Keratoconus |url=https://www.hopkinsmedicine.org/health/conditions-and-diseases/keratoconus |access-date=2024-05-08 |website=www.hopkinsmedicine.org |language=en}}</ref> Down syndrome is a strong risk factor for developing keratoconus, and onset may be occur at a younger age than in those without Down syndrome.<ref name=":02"/>  Eye rubbing is also a risk factor for developing keratoconus.<ref name=":33" />  It is speculated that chronic eye irritation from [[blepharitis]] may increase eye rubbing in Down syndrome,<ref name=":02"/> contributing to the increased prevalence of keratoconus.

An association between [[glaucoma]] and Down syndrome is often cited.<ref name="Wei20102"/>  Glaucoma in children with Down syndrome is uncommon, with a prevalence of less than 1%.<ref name="Wei20102"/><ref name=":02"/>  It is currently unclear if the prevalence of glaucoma in those with Down syndrome differs from that in the absence of Down syndrome.<ref name=":02"/>

Estimates of [[prevalence]] of ocular findings in Down Syndrome vary widely depending on the study.<ref name=":02"/>  Some prevalence estimates follow. Vision problems have been observed in 38–80% of cases.<ref name="Wei20102"/> [[Brushfield spots]] are present in 38–85% of individuals.<ref name="Wei20102" />  Between 20 and 50% have [[strabismus]].<ref name="Wei20102" /> [[Cataract]]s occur in 15%,<ref name="Nelson20112">{{cite book |title=Nelson textbook of pediatrics |vauthors=Kliegma RM |publisher=Saunders |year=2011 |isbn=978-1-4377-0755-7 |edition=19th |location=Philadelphia |pages=Chapter 76.2 |chapter=Down Syndrome and Other Abnormalities of Chromosome Number}}</ref> and may be present at birth.<ref name="Wei20102" /> [[Keratoconus]] may occur in as many as 21–30%.<ref name=":02" />