On the necessity of screening and national registration of congenital cataracts

Abstract

Objectives: The overall aim of this thesis was to contribute to improvements in the management of congenital cataract by defining the most efficient screening procedure, examining the magnitude of the morbidity rate, optimizing the timing of surgery by relating surgical outcome to age at intervention and severity of visual deprivation and furthermore by evaluating costs versus consequences of introducing the most efficient screening procedure found, on a national basis.Methods: Paper I: 72 children born between 1992 and 1998 in the Stockholm County Council region, Västra Götaland and Halland county, Linköping-Motala, Malmö, and Lund, who had surgery for congenital cataract before the age of one year were included in a retrospective study. Papers II to IV: A total of 160 children with a diagnosis of congenital cataract born between January 1980 and December 1999 in Västra Götaland and Halland county, Sweden, were included in a longitudinal prospective study. Paper V: Two scenarios were created, representing combined maternity ward/ well-baby clinic screening and well-baby clinic screening, solely, based on data of Papers I to IV. These scenarios were compared regarding health care costs, visual acuity development and quality-adjusted life years (QALYs). Results: Eye screening at the maternity ward is preferable to well-baby clinic screening and to no screening at all, since it leads to early detection. Screening should also be made routine performance at well-baby clinics within the period where successful treatment is possible. The occurrence rate of congenital cataract in western Sweden was 36 cases per 100,000 births. The final value of visual acuity (VA) was 0.4 or above for approximately 50 % in the group of total bilateral congenital cataracts at 12 years of age. Children operated on before 7 weeks of age achieved higher values of VA at 4 years of age compared to children operated on between 7 weeks and one year of age. However, no statistically significant difference in VA results among these groups could be proven. Visual acuity improves to a considerable extent after school age in children with delayed visual development caused by congenital cataracts. Surgery within 7 weeks results in a more rapid development of VA, initially.Despite modern surgical techniques, the incidence of aphakic glaucoma is 10% or higher. Posterior capsular opacification (PCO) developed in 31% of the operated eyes. Risk factors for development of postoperative glaucoma were young age at surgery (<10 days), and microphthalmus. Bearing in mind the relationship between very early surgery and development of glaucoma, it may be reasonable to avoid surgery during the first weeks of life. Unlike unilateral cataracts, there is a possibility that the influence of age at surgery in bilateral cataracts is limited during the first period of life.The cost-effectiveness ratio was 234,000 SEK/QALY representing the maternity ward/well-baby clinic screening scenario. This screening routine is cost-effective and found to be within acceptable levels of cost/QALY when compared with other widely accepted therapies across diverse medical specialties.Further evaluations require larger cohorts due to the low incidence of congenital cataracts and the numerous covarying factors. A national congenital cataract register, which will be launched in early 2004, will make it possible to investigate data prospectively and retest the results regarding issues of the present thesis, as well as other important questions.