Basics
Description
Cataract is the term used for any opacification of the crystalline lens of the eye.
Epidemiology
- Approximately 4 children per million total population will be born with bilateral congenital cataracts in developed countries.
- Adjusted cumulative incidence is 2.49 per 10,000 in the 1st year of life, increasing to 3.46 by age 15 years.
General Prevention
- There is currently no known way to prevent congenital cataracts. Timely prenatal diagnosis and treatment of intrauterine infections can prevent associated infant morbidities, including secondary cataracts. Correcting an underlying metabolic abnormality and minimizing exposure to inciting agents also reduces risk.
- It is essential that all newborns (and all children) receive screening eye examinations by health care providers. In much of the world, early diagnosis and referral is still the limiting factor for a child's ultimate visual prognosis.
Pathophysiology
- Derangement of the normal developmental growth of the crystalline fibers of the central lens nucleus or peripheral lens cortex. The location of the opacity often suggests the congenital or early acquired onset.
- Frequently classified according to morphology or etiology
- Dense central opacities of ≥3 mm are visually significant and may produce visual disability.
Etiology
- Congenital or developmental: About 2/3 are idiopathic, the remainder being inherited or associated with systemic disorders.
- Hereditary: Autosomal dominant transmission is responsible for 75% of bilateral hereditary cataracts. Most affected individuals are otherwise healthy.
- Phenotypically identical cataracts can occur with mutations at different genetic loci and phenotypically variable cataracts can be found within a single family.
- Multiple contributing genetic loci have been identified.
- Rare hereditary syndromes combine cataracts with systemic disease. These are listed in the following discussion.
- Acquired
- Toxic: may result from chronic steroid use or radiation exposure
- Traumatic: may result from either blunt or penetrating ocular trauma
- Inflammatory: from chronic uveitis
- Ocular abnormalities: Cataracts may be associated with primary ocular abnormalities such as aniridia, coloboma, and microcornea.
Commonly Associated Conditions
- Prenatal factors: intrauterine infection, fetal alcohol syndrome
- Metabolic and endocrine: galactosemia, neonatal hypoglycemia, hypoparathyroidism, diabetes mellitus, homocystinuria, Fabry disease, Wilson disease, mannosidosis
- Chromosomal: trisomy 21 (Down syndrome), 18, 13, or 15; Turner syndrome
- Dermatologic: congenital ichthyosis, hereditary ectodermal dysplasia, infantile poikiloderma, Gorlin syndrome
- Renal: Lowe and Alport syndromes
- Musculoskeletal: Marfan, Conradi, and Albright syndromes; myotonic dystrophy
- Rheumatologic: juvenile idiopathic arthritis, other uveitis (psoriatic, HLA-B27, etc.)
- Other: craniofacial and mandibulofacial syndromes, neurofibromatosis
Diagnosis
History
- Decreased visual fixation and tracking? Cataracts may decrease vision.
- Sun sensitivity or squinting in bright light? Cataracts may cause glare and light scatter.
- Strabismus (ocular misalignment)? May indicate loss of vision in one eye
- White pupil? Cataracts may appear as a white spot in or under the pupil.
- Asymmetric or abnormal pupillary reflections (red eyes) with flash photography? Cataract may block the normal red reflex.
- Nystagmus (rhythmic oscillations)? May be a sign of severe, usually bilateral, vision loss
- Ocular trauma? Cataract can occur from blunt or penetrating trauma.
- Delayed development? Especially with significant bilateral congenital cataracts
- Careful family and prenatal history? Congenital cataracts can be inherited as an isolated condition. Intrauterine infection or alcohol exposure can cause cataracts.
- Positive family history or known history of an associated systemic condition?
Physical Exam
- Decreased visual acuity: In preverbal child, assess and compare ability to fixate and follow with each eye. In verbal child, assess with pictures, HOTV matching, or alphabet (Snellen) eye chart.
- Leukocoria: white pupil
- Red reflex: absent, asymmetric, or irregular. How much of the pupil is obscured? Use direct ophthalmoscope held at an arm's length to illuminate both eyes and compare the red reflex from each eye.
- Strabismus: often an indication; cataract is long-standing and amblyopia likely.
- Nystagmus: will first appear at 2-3 months of age if vision deprivation from cataract is present at birth. Very poor prognostic sign for full vision recovery unless treatment is prompt.
- Laterality of disease: Bilateral cataracts may be due to systemic disease.
- Globe (eyeball) size: Microphthalmia (small eye) suggests congenital cataracts.
- Complete physical exam: to assess for associated conditions
Diagnostic Tests & Interpretation
Lab
For cases with a definitive etiology, laboratory evaluation is typically not necessary. For bilateral cataracts without a clear cause, a selective workup to rule out associated conditions may be indicated.
- Serologies: titers to rule out TORCH infections; blood glucose, calcium, and phosphate to exclude metabolic disorders such as diabetes and hypoparathyroidism
- Urine tests: reducing substances to rule out galactosemia; protein, amino acids, and pH to rule out Lowe syndrome
- Red blood cell enzyme levels: galactokinase and gal-1-uridyltransferase as part of galactosemia workup
- Karyotype: in conjunction with genetic consultation and ocular examination of parents and siblings
Imaging
Ophthalmologist may perform ocular ultrasonography if unable to visualize structures posterior to the opacity.
Diagnostic Procedures/Other
- Complete, timely ophthalmic evaluation by a pediatric ophthalmologist, including slit-lamp biomicroscopy and dilated fundus examination
- Examination under anesthesia may be required if office-based exam is inadequate. Coupled with intent to remove cataract when necessary.
Differential Diagnosis
Childhood cataracts can be readily identified as such. However, they represent one of the many etiologies on the differential diagnosis for leukocoria.
- Cataracts may also be an expression of an underlying systemic disease, which must be diagnosed for the child's overall benefit.
- Leukocoria or poor red reflex differential diagnosis:
- Retinoblastoma
- Retinopathy of prematurity
- Persistent fetal vasculature
- Uveitis
- Retinal detachment
- Coats disease
- Toxocariasis
Treatment
Additional Treatment
General Measures
- Importance of timely referral:
- Congenital cataracts may require surgical removal by 4-6 weeks of age to prevent irreversible deprivation amblyopia, so quick referral is critical.
- Acquired pediatric cataracts may also cause amblyopia, typically prior to 7 years of age.
- Conservative management:
- Partial cataracts that do not block the visual axis may be managed with observation, pharmacologic pupillary dilatation, and/or amblyopia treatment as needed (occlusion of the contralateral eye). Glasses may or may not be of additional help.
- A small or partial cataract may progress, so close follow-up is required.
Surgery/Other Procedures
- Visually significant cataracts must be removed surgically. An intraocular lens (IOL) may be inserted at the time of cataract surgery or later when the child is older.
- Successful intervention must occur very early in life in the case of visually significant congenital cataracts or as soon as possible after progression of later onset or partial cataracts.
- To prevent deprivation amblyopia in bilateral cases, both cataracts are typically removed within 1 or 2 weeks of each other. Rarely the eyes are operated simultaneously, if anesthesia risks are high.
- Postoperative care
- Overview: Removing the lens leaves the child aphakic (without a lens). Postoperative optical correction with contact lens, glasses, and/or IOL and amblyopia treatment are essential for optimal visual prognosis.
- Contact lens: In children <1 year of age, optical correction of aphakia is frequently accomplished with contact lenses or spectacles. An IOL is sometimes placed initially but more often is implanted after eye growth as a secondary procedure.
- IOL: In children >1 year of age, IOLs are frequently placed at the time of cataract surgery. Glasses are needed as well, even when an IOL is placed.
- Amblyopia therapy: In unilateral cataract cases, successful visual rehabilitation usually requires aggressive occlusion therapy to the normal eye, possibly for years.
Ongoing Care
Follow-up Recommendations
- Without treatment, visually significant cataracts result in progressive visual loss. When an opacity that is present at birth or very early in life is not promptly addressed, the visual loss quickly becomes irreversible.
- Once surgical removal is performed and optical correction is started, the child, the parents, and the ophthalmologist enter into an intensive and long rehabilitation period, lasting until visual maturity is reached (usually 7-10 years of age). Afterward, yearly eye examinations remain a minimum requirement.
- Parental and educational support services as well as special local, state, and federal services for the visually handicapped and blind may be required as not all children with successful surgical results will have good vision.
Alert
Pitfalls include (i) lack of early diagnosis, referral, and treatment; (ii) lack of understanding of irreversible deprivation amblyopia; (iii) lack of adherence with postoperative optical correction and occlusion therapy; and (iv) lack of continued long-term follow-up to detect and treat late glaucoma or shift in refractive errors with continued eye growth.
Prognosis
- Early surgery and rapid postsurgical optical correction result in best corrected visual acuities of 20/40-20/200 for monocular cataracts and 20/40 or better for bilateral cataracts. 20/20 is obtained in some patients.
- With dense unilateral cataracts, good vision is obtained if the surgery is completed within the first 6 weeks of life. After this time, visual restoration becomes progressively more difficult because of deprivation amblyopia.
- The prognosis for visual rehabilitation in children with bilateral congenital cataracts is better than for unilateral, as long as treatment is before vision deprivation nystagmus develops.
- Later onset and partial, slowly progressing cataracts have the best prognosis.
- Family adherence with both postsurgical optical correction and amblyopia treatment is critical and directly affects the child's ultimate visual outcome later in life.
Complications
- Lack of removal of a visually significant cataract at the appropriate time leads to irreversible deprivation amblyopia.
- Cataract removal in children leaves the eye without the natural crystalline lens-a structure that normally changes to offset the effects of eye growth. Even when an IOL is placed, glasses are often needed and these change frequently as the eyes grow. Unless appropriate optical correction is maintained, irreversible refractive amblyopia may still occur after the cataract is removed, particularly if the cataract is unilateral.
- Congenital cataract eyes often have immature outflow (trabecular meshwork) and 30% or more will eventually develop glaucoma (often years after surgery), requiring drops or surgery to control eye pressure.
- Short- and long-term postoperative complications also include visual axis opacification, retinal detachment, and, very rarely, endophthalmitis (intraocular infection). These complications may lead to vision loss or loss of the eye, and long-term ophthalmology follow-up is required.
Additional Reading
- Amaya L, Taylor D, Russell-Eggitt I, et al. The morphology and natural history of childhood cataracts. Surv Ophthalmol. 2003;48(2):125-144. [View Abstract]
- Infant Aphakia Treatment Study Group. A randomized clinical trial comparing contact lens with intraocular lens correction of monocular aphakia during infancy. Arch Ophthalmol. 2010;128(7):810-818. [View Abstract]
- Lambert SR, Drack AV. Infantile cataracts. Surv Ophthalmol. 1996;40(6):427-458. [View Abstract]
- Levin AV. Congenital eye anomalies. Pediatr Clin North Am. 2003;50(1):55-76. [View Abstract]
- Wilson ME Jr, Trivedi RH, Hoxie JP, et al. Treatment outcomes of congenital monocular cataracts: The effects of surgical timing and patching compliance. J Pediatr Ophthalmol Strabismus. 2003;40(6):323-329, quiz 353-354. [View Abstract]
Codes
ICD09
- 366.9 Unspecified cataract
- 743.30 Congenital cataract, unspecified
- 366.50 After-cataract, unspecified
- 366.45 Toxic cataract
- 366.20 Traumatic cataract, unspecified
ICD10
- H26.9 Unspecified cataract
- Q12.0 Congenital cataract
- H26.40 Unspecified secondary cataract
- H26.30 Drug-induced cataract, unspecified eye
- H26.103 Unspecified traumatic cataract, bilateral
- H26.101 Unspecified traumatic cataract, right eye
- H26.109 Unspecified traumatic cataract, unspecified eye
- H26.102 Unspecified traumatic cataract, left eye
- H26.32 Drug-induced cataract, left eye
- H26.33 Drug-induced cataract, bilateral
- H26.31 Drug-induced cataract, right eye
SNOMED
- 193570009 Cataract (disorder)
- 79410001 congenital cataract (disorder)
- 47337003 after-cataract (disorder)
- 38583007 Toxic cataract
- 34361001 traumatic cataract (disorder)
FAQ
- Q: Is surgical removal of the cataract a visual cure?
- A: No. Surgery is only the beginning of treatment, which also includes optical correction and amblyopia therapy.
- Q: Once the cataract is removed, will intensive, extensive follow-up be needed?
- A: Yes. The visual prognosis is directly related to postsurgical treatment compliance.
- Q: Is the cataract easier to treat when the child is older?
- A: No. Irreversible deprivation amblyopia develops as the child grows, precluding any chance for normal vision. In newborns, cataracts must typically be removed at 4-6 weeks of age.