Detection of Congenital Cataracts
Abstract & Commentary
Synopsis: A substantial proportion of children with congenital and infantile cataracts are not being detected by 3 months of age using currently recommended routine ocular examinations in the newborn period and again at 6-8 weeks of age. Dense cataracts must be treated surgically by 3 months of age to prevent visual loss.
Source: Rahi JS, Dezateux C. National cross sectional study of detection of congenital and infantile cataract in the United Kingdom: Role of childhood screening and surveillance. BMJ 1999;318:362-365.
Recommendations concerning the ocular examination of newborns have been in place in the United Kingdom since the 1960s. These recommended inspections of the eyes of all newborns include an evaluation of the pupillary red reflex of all infants in the first week of life and then again at 6-8 weeks of age.
To determine the mode of detection and timing of ophthalmological assessment of a nationally represented group of children with congenital and infantile cataract, Rahi and Dezateux, members of the British Congenital Cataract Interest Group, conducted a study of 235 children born in the United Kingdom between October 1995 and September 1996 in whom a cataract was newly diagnosed. Thirty-five percent (83/235) were detected in the routine neonatal exam and 12% (30/235) were detected at the 6-8-week examination. Eighty-two children presented because of symptoms. In 91 cases, the child’s caregiver had suspected an eye defect before the diagnosis of a cataract was made. Fifty-seven percent (137/235) of children had been assessed by an ophthalmologist by the age of 3 months, but one-third (78/235) were not examined by an ophthalmologist until after 1 year of age.
Comment by Richard A. Ehrenkranz, MD, FAAP
Although the definitive management of congenital cataracts is the province of a pediatric ophthalmologist, in most instances their recognition depends upon the pediatrician who performs the neonatal physical examination.
Congenital cataracts are recognized as an important, and potentially avoidable, cause of visual handicap throughout the world. There is a long list of conditions associated with cataracts in children, including infections, chromosomal disorders, and a large number of systemic conditions or metabolic disorders. The most common congenital cataracts are idiopathic. Regardless of the cause of the cataract, permanent visual loss can result from a dense, light-occluding, congenital cataract. Amblyopia is believed to result from light stimulus deprivation of the infantile retina, which prevents normal retinal images from forming and being transmitted to the visual cortex. It is believed that surgical treatment of dense congenital cataracts must take place within the first 3-4 months of life in order to prevent permanent blind-ness of the affected eye. Thus, early detection and referral to an ophthalmologist are of paramount importance.
The recommendations for neonatal ophthalmologic examination used in the United Kingdom at the time of this study are essentially the same as those followed in the United States.1 Demonstration of a symmetrical red reflex in a newborn that is elicited by an ophthalmoscope, focused on the pupil from 12 in to 18 in, indicates that the passage of light though the cornea, lens, and vitreous is probably normal and especially indicates that the posterior eye structures are normal. Absence or asymmetry of the red reflex or dark spots should be a cause for concern. The chemical conjunctivitis and swelling evoked by prophylactic silver nitrate applications into the newborn’s eyes may make it difficult to elicit a red reflex, but the increasing use of antibiotic eyedrops has made this much less of a problem. However, it is not uncommon to be unable to elicit an adequate red reflex—at least the first time around.
The results of Rahi and Dezateux indicate that currently recommended practices for the neonatal diagnosis of congenital cataracts fail to detect a significant number of babies who are subsequently diagnosed as having cataracts, some of whom are permanently blinded. There is no reason to think that a similar situation is not also present in the United States. Unfortunately, their study was unable to tell in most instances whether failure to detect a congenital cataract was because an appropriate examination was not performed (an error of omission) or whether the exam was performed incorrectly (an error of commission). The short postnatal stays that are increasingly common today present a challenge to the pediatrician performing a complete neonatal examination, including the eyes. However, a successful assessment of the red reflex should be considered an essential part of the newborn exam. If it can’t be successfully accom-plished in the newborn nursery, it is certainly incumbent to do it in the first few weeks after birth.
1. Committee on Practice and Ambulatory Medicine on Ophthalmology. American Academy of Pediatrics. Eye examination and vision screening in infants, children, and young adults. Pediatrics 1996;98:153-157.
True statements about congenital cataracts include all of the following except:
a. detection requires a slit lamp examination.
b. they can cause amblyopia.
c. most are idiopathic.
d. they should be surgically treated before three months of age.