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PAPERS: Jugnoo S Rahi and Carol Dezateux 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 [Abstract] [Full text]

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An even more specific screening test is needed

Stephen Morgan   (16 February 1999)

Pupils should be dilated prior to examination

G G W Adams   (23 March 1999)

Late diagnostic - a very important issue

Antonio Jordao   (1 April 1999)

An even more specific screening test is needed 16 February 1999
Stephen Morgan Send response to journal: Re: An even more specific screening test is needed	Rahi and colleagues have provided helpful data enabling the annual incidence of congenital cataracts in the UK to be estimated.(1) Allowing for their assessment of the non-completeness of the data the incidence is approximately 3 per 10000 live births. While this rarity does not make the condition unimportant it does raise very considerable difficulties for a screening programme. This is especially so when the apparently simple screening test relies on the interpretation of a clinical sign which to elicit from many infants is far from straightforward in the circumstances in which the test is usually performed. The challenge for the clinician is to retain high sensitivity for detecting the abnormality without unduly reducing the specificity. In addition the clinician has to be prepared to resist the inevitable pressure to reduce their sensitivity in the light of the large number of false positives they detect. To put this in perspective only one in every 180 infants referred for further assessment would have the diagnosis confirmed even if the clinician achieves the very impressive 93% sensitivity and 95% specificity achieved in the small study of ophthalmoscopic diagnosis in 3 to 30 year old subjects to which the authors refer.(2) Thus a hospital paediatrician doing 20 assessments a week would see one case in 4 years but would have referred one case each week throughout that time. In the community a full time GP would refer one case each year but it would take 6 working lifetimes to see a true case. Faced with this level of false positives most clinicians are likely to increase their specificity substantially with the almost inevitable result that their diagnostic sensitivity falls. That the current screening programme achieves about 50% sensitivity may be a cause for modest celebration. Unless an even more specific screening test is developed attempts to reduce the number of cases missed by the current system will require the screening doctors and ophthalmologists to accept many more false positive referrals than might usually be judged as acceptable clinical practice for other diagnoses. 1. 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 2. Ruttum, M.S., Nelson, D.B., Wamser, M.J., Balliff, M. Detection of congenital cataracts and other ocular media opacities. Pediatrics 1987;79:814-817. Stephen Morgan Primary Medical Care University of Southampton Aldermoor Health Centre Aldermoor Close Southampton SO16 5ST
Pupils should be dilated prior to examination 23 March 1999
G G W Adams Send response to journal: Re: Pupils should be dilated prior to examination	EDITOR - We congratulate Ms Rahi and co-workers on a beautifully conducted study looking at the detection of congenital and infantile cataract in the United Kingdom (ref 1). Their findings that only 57% of the children with congenital cataract had been assessed by an ophthalmologist by 3 months, while 33% did not see an ophthalmologist until after 1 year of age are very disturbing. If a visually disabling congenital cataract is not operated on by the age of 3 months, the chances of development of life-long nystagmus are high, and this generally results in poor visual outcome. The authors suggest a number of reasons, including poor technique and possibly the cataract not being dense enough to obscure the red reflex at birth. We would like to suggest a number of additional factors including poor training, with the initial examination being left to junior and inexperienced staff, conducted with the small pupil of the new-born baby. A small undilated pupil makes examination of the red reflex particularly difficult in a baby with dark irides, such as in Afro-Caribbean and Asian babies. Therefore, we suggest that all new-born babies have their pupils dilated with one drop of Cyclopentolate 0.5% eye drops 30 to 40 minutes before the examination of the red reflex. The literature lists a number of side-effects associated with the use of Cyclopentolate eye drops, but these are found with the use of the 1 or 2% formulation (refs 2 and 3). As far as we are aware no serious side-effects have been reported with the use of 0.5% Cyclopentolate. This is also born out by the personal experience of one of us (GGWA) over a thirteen year period in paediatric ophthalmology where the use of 0.5% Cyclopentolate for pupil dilation in premature infants for screening and treatment for retinopathy of prematurity and, for older babies, screening for congenital cataract has not resulted in any major side-effects. GGW Adams Consultant ophthalmic surgeon Strabismus and Paediatric Service Abdul Rauf Fellow Strabismus and Paediatric Service Jill Bloom Pharmacist Moorfields Eye Hospital City Road London EC1V 2PD 1 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;318:362-5 2 Havener WH. Ocular Pharmacology. 5th ed. St. Louis : CV Mosby, 1983;393-398 3 Awan KJ. Adverse systemic reactions of topical cyclopentolate hydrochloride. Ann of Ophthalmol 1976;8:695-698
Late diagnostic - a very important issue 1 April 1999
Antonio Jordao, ? Faculdade de Medicina de Ribeirao Preto - USP - Brasil Send response to journal: Re: Late diagnostic - a very important issue	First of all I'd like to congratulate the authors for the excellent paper. I'm finishing my master theses working with infantile cataracts, having examined about 230 children between Jun/95 and Dec/98. For my surprise, the diagnostic of the impaired vision was done in most of the cases by the children's mother, followed by schools screening programs and at last by an ophthalmologist. The medium age for the first ocular examination of the children at our reference Hospital was 3 YEARS!!! Although we have a very different social-politic situation in Brasil than you have in UK that's unacceptable! I just can encourage all the programs that aim to promote an earlier diagnostic of the infantile cataracts, and put all my data available to any of the authors interested in an international collaboration.