About 60% of patients with Down syndrome have ophthalmic manifestations. Ocular findings in patients with trisomy 21 include a wide range of visual acuities due to refractive errors and amblyopia, strabismus, nystagmus, lid anomalies and infections, amblyopia, corneal ectasias, Brushfield spots, presenile cataracts, glaucoma, and retinovascular anomalies. [1, 2] Patients with Down syndrome may develop amblyopia due to strabismus, refractive errors, or media opacities associated to corneal hydrops or cataracts. [3, 4, 5, 6, 7, 8]
A pediatric ophthalmologist should evaluate patients with Down syndrome in the first 6 months of life and annually thereafter if no eye pathology is present.
See also the following:
A clinical history is usually obtained from a third party. Determine the patient's age, and obtain a chief complaint. In addition, in history of present illness (HPI) include the parental age at conception, previous eyeglasses prescriptions, occlusion therapy for amblyopia, onset of strabismus and/or nystagmus, previous external infections and treatment modalities, tearing, and photophobia. Also inquire about previous strabismus and/or cataract surgery.
Review cardiovascular systems, and obtain a history of any previous cardiovascular surgery, including complications associated to general anesthesia. Furthermore, review the patient's pulmonary, gastrointestinal, endocrine, hematologic, and neurologic systems.
Visual acuity assessment
Visual acuity is evaluated in patients with Down syndrome according to the patient's intelligence and responsiveness. [9, 10] In the nonverbal patient, vision is evaluated in terms of quality (good, fair, or poor), location (central vs eccentric), and duration (maintained vs sporadic). In a verbal patient, visual acuity may be assessed using optotypes (eg, Allen or Tellen cards, tumbling E or Snellen charts).
Poor visual acuity and amblyopia in patients with Down syndrome may be due to degradation in optical quality and neurologic deficits.
Observe the patient's visual behavior, eye movements, fixation, alignment, and head posturing. Evaluate the eyes for involuntary movements (ie, nystagmus).
Presence of a head tilt or face turn usually indicates the presence of nystagmus with a null point or an incomitant strabismus with compensatory head positioning. Up to 20% of patients with Down syndrome have strabismus.
Goals of a strabismus examination are as follows:
Evaluation of the type of strabismus
Measurement of the deviation; methods for measuring ocular deviation include light reflex tests and cover tests. Light reflex tests are easier than but not as precise as cover tests.
Evaluation of ductions and versions
Evaluation of face turns or head tilt
Evaluation of restriction and paresis
Lid anomalies assessment
Congenital lid anomalies in patients with Down syndrome include prominent epicanthal folds, upward slanting of the palpebral fissures, and congenital ectropion (rare). Patients frequently have lid infections, including blepharitis, blepharoconjunctivitis, chalazion, and hordeola. Because of recurrent external infections, inspect the lids for collarettes, foamy secretions, Meibomian plugging, marginal erythema, and scurf. Furthermore, patients with Down syndrome may have nasolacrimal duct obstruction. 
Anterior segment assessment
Evaluate corneas carefully for keratoconus, keratoglobus, or corneal hydrops. Scissoring of the retinoscopic reflex is an early finding in patients with keratoconus. Placido disks, keratometers, or topographies can be used to evaluate cooperative patients with Down syndrome who have keratoconus. Rizzuti and Munson signs appear later.
Iris' Brushfield spots may occur in up to 90% of patients with trisomy 21. Brushfield spots are focal areas of iris stromal hyperplasia surrounded by relative hypoplasia. These spots are more common in patients with lightly pigmented irides.
Cataracts may be congenital or may occur later in life. Lens opacities may be sutural, zonular, or complete.
Glaucoma usually occurs during infancy. Therefore, patients must be examined for corneal edema, megalocornea, increased intraocular pressure, and optic nerve cupping, as part of a comprehensive ophthalmic examination.
Previous studies describe an increased number of retinal vessels crossing the disk margin.
A dilated ophthalmoscopic retina evaluation is recommended, since glaucoma and retinal detachments have been reported in patients with Down syndrome. Furthermore, previous studies by O’Brien and coworkers  have suggested abnormal macular development due to increased inner and outer retinal layers in patients with Down syndrome, as shown on optical coherence tomography (OCT).
Refractive error assessment
Conducting a cycloplegic refraction is of utmost importance, as patients with Down syndrome may have high refractive errors, which, if left uncorrected, may lead to amblyopia.
A primary care provider should lead and coordinate the multisystemic evaluation of patients with Down syndrome. Awareness of systemic and ocular findings is essential for managing patients with trisomy 21. [13, 14]
Medical treatment of external eye diseases for patients with Down syndrome is the same as that for nonhandicapped patients. In the medical treatment of glaucoma, avoid medications with cardiovascular and respiratory tract side effects.
Medical therapy for blepharitis that is recommended for nonhandicapped patients is also used for patients with Down syndrome. This treatment includes lid scrubs and topical antibiotics. Treatment of blepharitis is of utmost importance before intraocular surgery.
Indications used for eyeglass prescriptions for nonhandicapped patients are also used for patients with Down syndrome. Glasses should be prescribed for patients at risk for amblyopia due to refractive errors, accommodative esotropia, aphakia, and pseudophakia.
As with medical therapy, surgical indications that are used for nonhandicapped patients are also used for patients with Down syndrome. General anesthesia is advised during surgical intervention. In addition, maintain open communication with primary care providers, legal guardians, and caretakers. Carefully explain and ensure that they understand potential surgical complications. Obtain complete preoperative informed consent.
Systemic evaluation, including a cardiovascular evaluation, is desirable before ophthalmic surgery. Congenital cardiac malformations may require early cardiovascular surgery.
Patients may benefit from strabismus surgery.
A 2015 report by Sabti and coworkers  suggests that early corneal crosslinking halts keratoconus progression in patients with the Down syndrome. Patients with keratoconus who develop corneal hydrops and scarring may benefit from corneal transplantation.
Patients with Down syndrome have a high incidence of cataracts. Cataract extraction is indicated when decreased vision affects the patient's quality of life. Extracapsular cataract extraction with intraocular lens implantation facilitates visual rehabilitation. Phacoemulsification offers the advantage of a small incision.
Traumatic ocular injuries are treated when required. Patients with keratoglobus are at an increased risk of spontaneous corneal rupture following traumatic eye injuries.
As with any patient undergoing eye surgery, complications can occur during the perioperative and postoperative periods. Carefully monitor patients for bradycardia during strabismus surgery, and watch for complications following penetrating keratoplasty (eg, wound dehiscence due to blunt trauma).
Help prevent wound dehiscence and postoperative infections by performing small incision cataract surgery and using postoperative shields.
Prevent optical decentration in eyeglasses by examining the patient's pupillary distance (PD). Consider using monocular PD measurements as needed. Compare the patient's PD to the PD found in the eyeglasses. Consider advising the optician on the patient's dominant eye.
Because of the high frequency of congenital heart defects, avoid medications that may have cardiovascular side effects, such as atropine, beta-blockers, dipivefrin, and epinephrine.