Congenital Cataract 

Updated: Aug 17, 2018
Author: Mounir Bashour, MD, PhD, CM, FRCSC, FACS; Chief Editor: Hampton Roy, Sr, MD 

Overview

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.

See What the Eyes Tell You: 16 Abnormalities of the Lens, a Critical Images slideshow, to help recognize lens abnormalities that are clues to various conditions and diseases.

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.

Epidemiology

Frequency

United States

Incidence is 1.2-6 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.

Prognosis

Of persons with unilateral congenital cataracts, 40% develop visual acuity of 20/60 or better.

Of persons with bilateral congenital cataracts, 70% develop visual acuity of 20/60 or better.

The 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 (eg, contact lenses, aphakic glasses), possible patching for amblyopia, possible strabismus surgery, and glaucoma screenings.

Patients must be made aware of the risk of potential visual loss from amblyopia, retinal detachment, or glaucoma.

Repeated surgical procedures, including a secondary lens implant if other modalities of refractive correction fail, may be needed.

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 eMedicineHealth's Eye and Vision Center. Also, see eMedicineHealth's patient education article Cataracts.

 

Presentation

History

Congenital cataracts are present at birth but may not be identified until later in life. Prenatal and family history is helpful.

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.

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).[1] Patients with CALOs who have anisometropia of 1 diopter (D) or more are 6.5 times more likely to develop amblyopia.[1]

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.

Leukocoria or white reflex can be the presenting sign of a cataract. In fact, in a 2008 study by Haider et al, 60% of patients who presented with leukocoria had congenital cataracts (18% unilateral and 42% bilateral).[2] Other causes included retinoblastoma (11% unilateral and 7% bilateral), retinal detachment (2.8% unilateral and 1.4% bilateral), bilateral persistent hyperplastic primary vitreous (4.2%), and unilateral Coats disease (4.2%).[2]

Slit lamp examination of both eyes (dilated pupil) not only may confirm the presence of a cataract but also may identify the time when the insult occurred in utero and if there is other systemic or metabolic involvement.

Dilated fundus examination is recommended as part of the ocular examination for both unilateral cataract cases and bilateral cataract cases.

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.

Complications

See the list below:

  • Loss of vision even with aggressive surgical and optical treatment

  • Amblyopia

  • Glaucoma

  • Strabismus

  • Retinal detachment

 

DDx

Differential Diagnoses

 

Workup

Laboratory Studies

For unilateral cataracts, laboratory studies include TORCH titers and Venereal Disease Research Laboratory (VDRL) test.

For bilateral cataracts, laboratory studies include CBC, BUN, TORCH titers, VDRL, urine for reducing substances, red cell galactokinase, urine for amino acids, calcium, and phosphorus.

Imaging Studies

CT scan of brain may be performed.

Other Tests

See the list below:

  • Hearing test

  • With screening of genes associated with cataract: Fourteen common genes that include crystallin alpha A (CRYAA), CRYAB, CRYG s, CRYBA1, CRYBA4, CRYBB1, CRYBB2, CRYBB3; beaded filament structural protein 1 (BFSP1); gap function protein; alpha 3 (GJA3) and GJA8; and heat shock transcription factor 4, as well as other genes, can be amplified.[3]

 

Treatment

Medical Care

Medical therapy is directed at the 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.

Koc et al concluded that early age at cataract extraction and microcornea are risk factors for delayed-onset glaucoma.[4]

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 the 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 study is underway in the United States 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.)

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.[5] 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 concerns the primary implantation of flexible IOLs in infants younger than 1 year.[6] The population studied includes infants aged 3-11 months who have different forms of unilateral congenital cataracts.

A 2008 study by Capozzi et al showed that, in the first 42 months of age, corneal power (Km) and axial length (AL) values are significantly different according to age.[7] These findings have implications for the calculation of IOL power. Km values were significantly greater, and AL readings were shorter, in younger children (p< 0.001). No differences according to gender were found. As a group, eyes from unilateral cataract cases had significantly longer AL readings than those from bilateral cataract cases (p=0.029). In a small subgroup of unilateral cataract cases, for which readings from the clear lens eye were available (n. 39), Km values of the affected eye were significantly greater than that of the fellow healthy eye (p=0.007).

In a study published in the British Journal ofOphthalmology, Hoevenaars et al found that in determining the level of myopic change in children who underwent cataract surgery with IOL, those younger than 12 months had a higher shift and greater mean rate of refractive change per year versus older children, thereby reflecting the importance that age at surgery and laterality rate have when deciding the power of IOL implants.[8]

The Infant Aphakia Treatment Study found that rates of intraoperative complications (ICs), adverse events (AEs), and additional intraocular surgeries (AISs) 1 year after infants had undergone cataract surgery with IOL implantation were numerically higher but their functional impact does not clearly favor either treatment group.[9]

The amount of endothelial cell loss after cataract surgery with IOL implantaion in children is within an acceptable range and should not affect corneal clarity in the long run.[10]

Goggin et al found in a publicly funded hospital study that the manufacturer seems to underestimate the corneal plane effective cylinder power of its toric IOLs. By estimating the effective corneal plane cylinder power of the IOL, as altered by the anterior chamber depth and pachymetry and by the IOL sphere power, a better outcome could be achieved; however, this is not currently addressed by the manufacturer.[11]

Consultations

An ophthalmology consultation is essential to prevent visual loss as well as to make the appropriate diagnosis of the type of cataract.

A genetics evaluation is warranted if bilateral cataracts or any other anomalies are present.

Diet

Restriction of galactose, if galactosemia is present, may reverse the progression of the classic "oil droplet" cataract.

Prevention

A red reflex is essential not only in the newborn nursery but also in all office visits.

Frequent eye examinations help in the prevention of amblyopia.

Frequent glaucoma screenings are needed throughout the patient’s lifetime.