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Cataract, Congenital
Article Last Updated: Apr 13, 2006
AUTHOR AND EDITOR INFORMATION
Section 1 of 9  
Author: Mounir Bashour, MD, CM, FRCS(C), PhD, FACS, Assistant Professor of Ophthalmology, McGill University; Clinical Assistant Professor of Ophthalmology, Sherbrooke University; Medical Director, Cornea Laser and Lasik MD
Mounir Bashour is a member of the following medical societies: American Academy of Ophthalmology, American Association for Pediatric Ophthalmology and Strabismus, American College of International Physicians, American College of Surgeons, American Medical Association, American Society of Cataract and Refractive Surgery, American Society of Mechanical Engineers, American Society of Ophthalmic Plastic and Reconstructive Surgery, Biomedical Engineering Society, Canadian Medical Association, Canadian Ophthalmological Society, Contact Lens Association of Ophthalmologists, International College of Surgeons US Section, Ontario Medical Association, Quebec Medical Association, and Royal College of Physicians and Surgeons of Canada
Coauthor(s):
Johanne Menassa, MD, Staff Physician, Department of Ophthalmology, University of Laval Hospital, Quebec City;
C Corina Gerontis, MD, Consulting Staff, Departments of Pediatrics and Ophthalmology, Schneider Children's Hospital/Long Island Jewish Medical Center
Editors: Richard W Allinson, MD, Associate Professor, Department of Ophthalmology, Texas A&M University Health Science Center, Scott and White Clinic; Simon K Law, MD, PharmD, Assistant Professor of Ophthalmology, Jules Stein Eye Institute; Chief of Section of Ophthalmology Surgical Services, Department of Veterans Affairs Healthcare Center, West Los Angeles; J James Rowsey, MD, Former Director of Corneal Services, St Luke's Cataract and Laser Institute, Florida; Lance L Brown, OD, MD, Ophthalmologist, Affiliated With Freeman Hospital and St John's Hospital, Regional Eye Center, Joplin, Missouri; Hampton Roy Sr, MD, Associate Clinical Professor, Department of Ophthalmology, University of Arkansas for Medical Sciences
Author and Editor Disclosure
Synonyms and related keywords:
congenital cataracts, cataract extraction, cataract surgery, deprivation amblyopia, refractive amblyopia, glaucoma, vision loss, visual deficit, blindness, rubella
Background
A cataract is an opacification of the lens. Congenital cataracts usually are diagnosed at birth. If a cataract goes undetected in an infant, permanent visual loss may ensue. Not all cataracts are visually significant. If a lenticular opacity is in the visual axis, it is considered visually significant and may lead to blindness. If the cataract is small, in the anterior portion of the lens, or in the periphery, no visual loss may be present.
Unilateral cataracts are usually isolated sporadic incidents. They can be associated with ocular abnormalities (eg, posterior lenticonus, persistent hyperplastic primary vitreous, anterior segment dysgenesis, posterior pole tumors), trauma, or intrauterine infection, particularly rubella. Bilateral cataracts are often inherited and associated with other diseases. They require a full metabolic, infectious, systemic, and genetic workup. The common causes are hypoglycemia, trisomy (eg, Down, Edward, and Patau syndromes), myotonic dystrophy, infectious diseases (eg, toxoplasmosis, rubella, cytomegalovirus, and herpes simplex [TORCH]), and prematurity.
Pathophysiology
The lens forms during the invagination of surface ectoderm overlying the optic vesicle. The embryonic nucleus develops by the sixth week of gestation. Surrounding the embryonic nucleus is the fetal nucleus. At birth, the embryonic and fetal nuclei make up most of the lens. Postnatally, cortical lens fibers are laid down from the conversion of anterior lens epithelium into cortical lens fibers.
The Y sutures are an important landmark because they identify the extent of the fetal nucleus. Lens material peripheral to the Y sutures is lens cortex, whereas lens material within and including the Y sutures is nuclear. At the slit lamp, the anterior Y suture is oriented upright, and the posterior Y suture is inverted.
Any insult (eg, infectious, traumatic, metabolic) to the nuclear or lenticular fibers may result in an opacity (cataract) of the clear lenticular media. The location and pattern of this opacification may be used to determine the timing of the insult as well as the etiology.
Frequency
United States
Incidence is 1.2-6.0 cases per 10,000.
International
Incidence is unknown; although the World Health Organization and other health organizations have made outstanding strides in vaccinations and disease prevention, the rate of congenital cataracts is probably much higher in underdeveloped countries.
Mortality/Morbidity
- Visual morbidity may result from deprivation amblyopia, refractive amblyopia, glaucoma (as many as 10% post surgical removal), and retinal detachment.
- Metabolic and systemic diseases are found in as many as 60% of bilateral cataracts.
- Mental retardation, deafness, kidney disease, heart disease, and other systemic involvement may be part of the presentation.
Age
Congenital cataracts usually are diagnosed in newborns.
History
- Congenital cataracts are present at birth but may not be identified until later in life.
- Some cataracts are static, but some are progressive. This explains why not all congenital cataracts are identified at birth.
- Anterior polar cataract and nuclear cataract are usually static, although they may rarely progress.
- Cataracts that typically progress include posterior lenticonus, persistent hyperplastic primary vitreous, lamellar, sutural, and anterior or posterior subcapsular. They usually have a better prognosis because they only usually begin to obstruct the vision after the critical period of visual development has passed.
- Not all cataracts are visually significant. If a lenticular opacity is in the visual axis, it usually is considered visually significant and requires removal.
- Cataracts in the center of the visual axis that are greater than 3 mm in diameter are generally considered visually significant. This principle is furthermore correlated with the clinical ophthalmological examination of the patient.
- In 2005, a study by the Department of Pediatric Ophthalmology of the Wills Eye Hospital concluded that, in terms of the risk factor for amblyopia, more important than the cataract size is the anisometropia induced by the congenital anterior lens opacities (CALOs). Patients with CALOs who have anisometropia of 1 diopter (D) or more are 6.5 times more likely to develop amblyopia.
Physical
- A lenticular opacity is called a cataract. Not all cataracts are visually significant.
- Description of a congenital cataract must include location, color, density, and shape for purposes of identification.
- An irregular red reflex is the hallmark of visual problems. If an irregular red reflex is detected at the initial screening, this is usually an indication that a congenital cataract might be present and an ophthalmology consultation is warranted.
- Slit lamp examination of both eyes confirms not only the presence of a cataract, but it also may identify the time when the insult occurred in utero and if there is other systemic or metabolic involvement.
Causes
- The most common etiology includes intrauterine infections, metabolic disorders, and genetically transmitted syndromes. One third of pediatric cataracts are sporadic; they are not associated with any systemic or ocular diseases. However, they may be spontaneous mutations and may lead to cataract formation in the patient's offspring. As many as 23% of congenital cataracts are familial. The most frequent mode of transmission is autosomal dominant with complete penetrance. This type of cataract may appear as a total cataract, polar cataract, lamellar cataract, or nuclear opacity. All close family members should be examined.
- Infectious causes of cataracts include rubella (the most common), rubeola, chicken pox, cytomegalovirus, herpes simplex, herpes zoster, poliomyelitis, influenza, Epstein-Barr virus, syphilis, and toxoplasmosis.
Retinoblastoma
Other Problems to be Considered
Corneal opacity (ulcer, scar, dermoid)
Persistent hyperplastic primary vitreous
Retinal detachment
Lenticular coloboma
Lab Studies
- Unilateral cataracts
- Prenatal and family history
- Slit lamp examination in both eyes (dilated pupil)
- Dilated fundus examination
- Laboratory studies include TORCH titers and Venereal Disease Research Laboratory (VDRL) test.
- Bilateral cataracts
- Prenatal and family history
- Slit lamp examination in both eyes (dilated pupil)
- Dilated fundus examination
- Genetics evaluation
- Laboratory studies include CBC, BUN, TORCH titers, VDRL, urine for reducing substances, red cell galactokinase, urine for amino acids, calcium, and phosphorus.
Imaging Studies
Other Tests
Medical Care
Prevention of amblyopia
Surgical Care
- Cataract surgery is the treatment of choice and should be performed when patients are younger than 17 weeks to ensure minimal or no visual deprivation. Most ophthalmologists opt for surgery much earlier, ideally when patients are younger than 2 months, to prevent irreversible amblyopia and sensory nystagmus in the case of bilateral congenital cataracts. The delay in surgery is because of glaucoma. Since glaucoma occurs in 10% of congenital cataract surgery, many surgeons delay the cataract surgery.
- Unfortunately, the improved surgical techniques of the 1990s have not lowered the incidence of glaucoma from the series published in the 1980s. The development of glaucoma (which occurs in later years) only occurs in cataract eyes that undergo surgery. This may be in part due to the immaturity of the angle at the time of surgery. A delay of a few weeks allows the angle of the immature eye to develop.
- A 2005 publication concluded that early age at cataract extraction and microcornea are risk factors for delayed-onset glaucoma.
- Extracapsular cataract extraction with primary posterior capsulectomy and anterior vitrectomy is the procedure of choice (via limbal or pars plana approach). Intracapsular cataract extraction in children is contraindicated because of vitreous traction and loss at Wieger capsulohyaloid ligament. Vitrectomy instrumentation is the preferred method since the lens material is very soft. The whole procedure can be performed using one intraocular instrument. Young eyes develop capsular opacification very quickly necessitating primary capsulectomy at the time of cataract extraction.
- A new US study is underway to determine if intraocular lens placement in children younger than 6 months is a viable option. (Several articles have already been published in British journals.)
- In 2005, a study by the Retina Foundation of the Southwest in Texas compared intraocular lens (IOL) implantation with aphakic contact lenses (CLs) after the extraction of a unilateral cataract. Patients were as young as 6 months. They concluded that IOLs and aphakic CLs support similar visual acuity development after surgery for a unilateral cataract. IOLs may support better visual acuity development when compliance with CL wear is moderate to poor or when a cataract is extracted in a patient older than 1 year.
- A study with promising preliminary results is being done at the moment, concerning the primary implantation of flexible IOLs in infants younger than 1 year. The population studied are infants aged 3-11 months who have different forms of unilateral congenital cataracts.
Consultations
- An ophthalmology consultation is essential to prevent visual loss as well as make the appropriate diagnosis of the type of cataract.
- Genetics evaluation if bilateral or any other anomalies are present
Diet
Restriction of galactose, if galactosemia is present, may reverse the progression of the classic "oil droplet" cataract.
Deterrence/Prevention
- A red reflex is essential not only in the newborn nursery but in all office visits.
- Amblyopia prevention by frequent eye examinations
- Frequent glaucoma screenings throughout life
Complications
- Loss of vision even with aggressive surgical and optical treatment
- Amblyopia
- Glaucoma
- Strabismus
- Retinal detachment
Prognosis
- Of persons with unilateral cataracts, 40% develop vision of 20/60 or better.
- Of persons with bilateral congenital cataracts, 70% develop vision of 20/60 or better.
- Prognosis is poorer in persons with other ocular or systemic involvement.
Patient Education
- Removal of the cataract is only the beginning. Visual rehabilitation requires many years of refractive correction (contact lenses or aphakic glasses), possible patching for amblyopia, possible strabismus surgery, and glaucoma screenings.
- Awareness of the risk of potential visual loss either from amblyopia, retinal detachment, or glaucoma.
- Possible need for repeated surgical procedures, including secondary lens implant if other modalities of refractive correction fail.
- If this is a de novo chromosomal change or a familial abnormality, all siblings and future offspring are at risk.
- For excellent patient education resources, visit eMedicine's Eye and Vision Center. Also, see eMedicine's patient education article Cataracts.
Medical/Legal Pitfalls
- Since there is a high association of systemic and metabolic abnormalities, genetic consultation is essential in bilateral cataracts. Some diseases may be preventable if diagnosis is made early.
- Biglan AW, Cheng KP, Davis JS, Gerontis CC. Secondary intraocular lens implantation after cataract surgery in children. Am J Ophthalmol. Feb 1997;123(2):224-34. [Medline].
- Birch EE, Cheng C, Stager DR. Visual acuity development after the implantation of unilateral intraocular lenses in infants and young children. J AAPOS. Dec 2005;9(6):527-32. [Medline].
- Brady KM, Atkinson CS, Kilty LA, Hiles DA. Cataract surgery and intraocular lens implantation in children. Am J Ophthalmol. Jul 1995;120(1):1-9. [Medline].
- Buckley E, Lambert SR, Wilson ME. IOLs in the first year of life. J Pediatr Ophthalmol Strabismus. Sep-Oct 1999;36(5):281-6. [Medline].
- Cassidy L, Taylor D. Congenital cataract and multisystem disorders. Eye. Jun 1999;13 ( Pt 3b):464-73. [Medline].
- Ceyhan D, Schnall BM, Breckenridge A. Risk factors for amblyopia in congenital anterior lens opacities. J AAPOS. Dec 2005;9(6):537-41. [Medline].
- Cheng KP, Hiles DA, Biglan AW, Pettapiece MC. Management of posterior lenticonus. J Pediatr Ophthalmol Strabismus. May-Jun 1991;28(3):143-9; discussion 150. [Medline].
- Koc F, Kargi S, Biglan AW. The aetiology in paediatric aphakic glaucoma. Eye 2005 Nov 11. [Medline].
- Mori M, Keech RV, Scott WE. Glaucoma and ocular hypertension in pediatric patients with cataracts. J AAPOS. Jun 1997;1(2):98-101. [Medline].
- Sidorenko EI, Shirshov MV, Korkh NL. Preliminary results of primary implantation of flexible intraocular lenses in infants under 1 year of age. Vestn Oftalmol. Sep-Oct 2005;121(5):37-8. [Medline].
Cataract, Congenital excerpt Article Last Updated: Apr 13, 2006
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