Congenital cataracts refers to a lens opacity which is present at birth. Congenital

cataracts A cataract is a cloudy area in the lens of the eye that leads to a decrease in vision. Cataracts often develop slowly and can affect one or both eyes. Symptoms may include faded colors, blurry or double vision, halos around light, trouble w ...

cover a broad spectrum of severity: whereas some lens opacities do not progress and are visually insignificant, others can produce profound visual impairment. Congenital cataracts may be

unilateral __NOTOC__ Unilateralism is any doctrine or agenda that supports one-sided action. Such action may be in disregard for other parties, or as an expression of a commitment toward a direction which other parties may find disagreeable. As a word, ''un ...

bilateral Bilateral may refer to any concept including two sides, in particular: * Bilateria, bilateral animals *Bilateralism, the political and cultural relations between two states *Bilateral, occurring on both sides of an organism ( Anatomical terms of ...

. They can be classified by morphology, presumed or defined genetic cause, presence of specific metabolic disorders, or associated ocular anomalies or systemic findings.

Signs and symptoms

Congenital cataracts occur in a variety of morphologic configurations, including lamellar, polar, sutural, coronary, cerulean, nuclear, capsular, complete, membranous.

Cause

In general, approximately one-third of congenital cataracts are a component of a more extensive syndrome or disease (e.g., cataract resulting from congenital rubella syndrome), one-third occur as an isolated inherited trait, and one-third result from undetermined causes. Metabolic diseases tend to be more commonly associated with bilateral cataracts.

Genetics

Approximately 50% of all congenital cataract cases may have a genetic cause which is quite heterogeneous. It is known that different mutations in the same gene can cause similar cataract patterns, while the highly variable morphologies of cataracts within some families suggest that the same mutation in a single gene can lead to different phenotypes. More than 25 loci and genes on different chromosomes have been associated with congenital cataract. Mutations in distinct genes, which encode the main cytoplasmic proteins of human lens, have been associated with cataracts of various morphologies, including genes encoding

crystallin In anatomy, a crystallin is a water-soluble structural protein found in the lens and the cornea of the eye accounting for the transparency of the structure. It has also been identified in other places such as the heart, and in aggressive breast c ...

s (CRYA, CRYB, and CRYG), lens specific

connexin Connexins (Cx)TC# 1.A.24, or gap junction proteins, are structurally related transmembrane proteins that assemble to form vertebrate gap junctions. An entirely different family of proteins, the innexins, form gap junctions in invertebrates. Ea ...

s (Cx43, Cx46, and Cx50), major intrinsic protein (MIP) or

Aquaporin Aquaporins, also called water channels, are channel proteins from a larger family of major intrinsic proteins that form pores in the membrane of biological cells, mainly facilitating transport of water between cells. The cell membranes of a v ...

, cytoskeletal structural proteins, paired-like homeodomain transcription factor 3 ( PITX3), avian musculoaponeurotic fibrosarcoma ( MAF), and heat shock transcription factor 4 ( HSF4).

Diagnosis

All newborns should have screening eye examinations, including an evaluation of the red reflexes. * The

red reflex The red reflex refers to the reddish-orange reflection of light from the back of the eye, or fundus, observed when using an ophthalmoscope or retinoscope. The reflex relies on the transparency of optical media (tear film, cornea, aqueous humor, c ...

test is best performed in a darkened room and involves shining a bright direct

ophthalmoscope Ophthalmoscopy, also called funduscopy, is a test that allows a health professional to see inside the fundus of the eye and other structures using an ophthalmoscope (or funduscope). It is done as part of an eye examination and may be done as part ...

into both eyes simultaneously from a distance of 1– 2 ft. This test can be used for routine ocular screening by nurses, pediatricians, family practitioners, and optometrists. *

Retinoscopy Retinoscopy (Ret) is a technique to obtain an objective measurement of the refractive error of a patient's eyes. The examiner uses a retinoscope to shine light into the patient's eye and observes the reflection (reflex) off the patient's retina. W ...

through the child's undilated pupil is helpful for assessing the potential visual significance of an axial lens opacity in a pre-verbal child. Any central opacity or surrounding cortical distortion greater than 3 mm can be assumed to be visually significant. * Laboratory Tests : In contrast to unilateral cataracts, bilateral congenital cataracts may be associated with many systemic and metabolic diseases. A basic laboratory evaluation for bilateral cataracts of unknown cause in apparently healthy children includes: : - Urine test for reducing substance, galactose 1-phosphate uridyltransferase, galactokinase, amino acids : - Infectious diseases: TORCH and varicella titers, VDRL : - Serum calcium, phosphorus, glucose and ferritin

Treatment

Surgery

In general, the younger the child, the greater the urgency in removing the cataract, because of the risk of

amblyopia Amblyopia, also called lazy eye, is a disorder of sight in which the brain fails to fully process input from one eye and over time favors the other eye. It results in decreased vision in an eye that typically appears normal in other aspects. Amb ...

. For optimal visual development in newborns and young infants, a visually significant unilateral congenital cataract should be detected and removed before age 6 weeks, and visually significant bilateral congenital cataracts should be removed before age 10 weeks. Some congenital cataracts are too small to affect vision, therefore no surgery or treatment will be done. If they are superficial and small, an ophthalmologist will continue to monitor them throughout a patient's life. Commonly, a patient with small congenital cataracts that do not affect vision will eventually be affected later in life; generally this will take decades to occur.

Epidemiology

* Congenital cataract are responsible for nearly 10% of all vision loss in children worldwide. * Congenital cataract are one of the most common treatable causes of visual impairment and blindness during infancy, with an estimated prevalence of 1 to 6 cases per 10,000 live births.

References

External links

{{Visual_pathways Eye Vision Ophthalmology Blindness Disorders of lens