Over forty years ago, it was believed there was no means of restoring vision in a child with a congenital cataract (Fig. 1 & 2).
Fig. 1: Undilated pupil of a patient with a congenital cataract.
Fig. 2: Dilated pupil of a patient with a congenital cataract.
Cataracts in infants and children has a reported prevalence in the literature from 1 to 15 per 10,000 children and it responsible for about 10% of childhood vision loss . There is a wide range in the reported prevalence due to definition criteria, methods of the ascertainment of data, geographic differences in population and level of economic development regarding screening methods and access to surgical care . The natural progression of congenital cataracts can lead to partial or complete blindness and even though it is still a leading cause of vision loss, it is now accepted that if detected early and intervention (Fig. 3) is applied in a prompt fashion before the end of the critical period of development is reached, a good visual outcome can be achieved.
Fig. 3: Lensectomy being performed on an infant with a unilateral congenital cataract.
In 1941, Sir Norman McAlister Gregg, an Australian ophthalmologist, reported the occurrence of congenital cataracts among 78 infants, 68 of which were born to mothers who had an early rubella infection in pregnancy . The unusual appearance of the cataracts affecting all except for the outermost layer of the lens led him to suggest the cataractous process began early in embryogenesis . Two years later in 1943 he and others added deafness and congenital heart disease to make the triad of congenital rubella embryopathy . The virus was isolated in 1961, and in 1969, a live attenuated rubella virus vaccine was licensed. Since this implementation of vaccination programs, this virus has largely been eliminated as a major cause of congenital malformation and disability , leading to a decline in the incidence of congenital cataracts. From 1962-63, 12 million people in the United States, including 20,000 infants, were infected by the rubella virus. In 2009, there were less than 75 infections reported in the U.S., however, 100,000 cases/year of rubella embryopathy occurred worldwide.
The Infant Aphakia Treatment Study
Sir Harold Ridley, a British ophthalmologist, first successfully implanted an intraocular lens after cataract surgery in 1949 at St Thomas' Hospital at London. The idea of implanting an intraocular lens reportedly came to him after an intern asked him why he was not replacing the lens he had removed during cataract surgery. Intraocular lenses did not gain widespread acceptance in adult cataract surgery until the 1970s, when further developments in lens design and surgical techniques had come about . Even though intraocular lenses (IOLs) were accepted in adults, for over thirty years, contact lenses (CTLs) were essentially the only means utilized for aphakic correction after unilateral cataract extraction in young children. Due to continued improvements in the technology and microsurgical techniques along with persistent issues with CTLs including a difficulty inserting and removing the lenses, high expense, and frequent loss of the lens, IOLs gradually began being increasingly used in the correction of aphakia in children following cataract surgery . IOLs are now generally considered as the standard of care for aphakia correction after cataract surgery in older children & adults, and are being increasingly used in infants and young children . IOLs have the advantage of providing an optical correction at all times, however, the challenge that must be considered is the rapidly changing optical needs of the child’s growing eye . Although the use of IOLs in young children was increasingly being used this treatment had ever been studied in a randomized clinical trial until 2004. The Infant Aphakia Treatment Study (IATS) is a multicenter, randomized, controlled clinic trial sponsored by the National Eye Institute. The objective of the study is to compare the use of immediate IOL implantation for the correction of aphakia with a contact lens after cataract surgery performed in infants with a unilateral congenital cataract before 6 months of age . One hundred fourteen patients were enrolled in the clinical trial between 2004 and 2009 at twelve clinical sites in the United States (Fig. 4).
Fig. 4: Infant Aphakia Treatment Study Participating Clinical Centers.
The primary outcome measures were grating visual acuity at 12 months of age using Teller Acuity Cards and Optotype Acuity at 4½ years of age. The median logMAR visual acuity between the contact lens group and the IOL group was not significantly different at one year of age. Additional intraocular operations were necessary in the IOL group in the data reported thus far. Optotype acuity outcomes at 4½ years of age are still being tested.
Simultaneous vs Sequential Cataract
Surgery for Infants with Bilateral Congenital Cataracts
Congenital cataracts are present bilaterally in the majority of children born with cataracts . In the United States, simultaneous bilateral cataract is not commonly performed, primarily because of a concern for developing bilateral endophthalmitis (Fig. 5) [10, 11].
Fig. 5: Patient with endophthalmitis following cataract surgery.
As in the treatment of unilateral congenital cataracts, visually significant bilateral cataracts require prompt surgical intervention to prevent the development of deprivational amblyopia. In order to expedite visual rehabilitation in both eyes and to avoid the child having to undergo the additional risk of undergoing general anesthesia more than once, some pediatric ophthalmologists advocate performing simultaneous bilateral cataract surgery in selected cases [12, 13, 14, 15]. Bilateral eye surgery is routinely performed in strabismus surgery, refractive surgery, blepharoplasty and intravitreal injections. In 1990 the Wills Eye Hospital reported 16 children that underwent simultaneous lensectomies, in 1996 the King Khalid Hospital reported 9 children underwent simultaneous lensectomies, and in 2010 the Children’s Hospital of Philadelphia reported 27 children that underwent simultaneous lensectomies, all but 3 patients < 1 year of age. Furthermore, in 2010 the Emory Eye Center reported 10 children who underwent sequential bilateral cataract surgery and compared them to 17 children who underwent simultaneous bilateral cataract surgery. They reported that simultaneous bilateral cataract surgery performed during infancy was associated with a 22% reduction in medical payments with no discernible difference in the incidence of visual outcomes or adverse events . Disadvantages of simultaneous bilateral cataract surgery include an increased potential risk of bilateral endophthalmitis, increased inaccuracy of biometry/IOL calculations and lower surgeon reimbursement (150% vs 200%). Advantages include faster visual rehabilitation, improved binocular vision, reduced direct and indirect costs, and fewer office visits (e.g. less time off from work, travel costs, etc.). In addition, benefits include avoiding two separate administrations of general anesthesia and hospitalizations if required. An anesthesia registry kept from 1994-1997 at 63 institutions (75% university affiliated) of all cardiac arrests in children following general anesthesia, showed 289 cardiac arrests (incidence 1.4/10,000), 55% occurred in infants < 1 year of age, 26% of patients died . In addition, when comparing the anesthetic exposure in children before the age of 4 and the development of reading, written language and math learning disabilities, there is evidence to suggest that exposure to anesthesia is a risk factor for the later development of learning disabilities in children receiving multiple general anesthetics .
In conclusion, there have been many changes in the management of childhood cataracts through the years based on advancing technologies and clinical studies. Evidence based research is constantly enhancing our understanding of the pathogenesis of childhood cataracts and providing us with more efficient means of visual rehabilitation affording the child affected with the best achievable visual and safety outcome.