Emporiatrics--travellers' health.

the management of borderline cases may be determined by a variety of techniques for testing vision. Most doctors managing such children, however, rely on behavioural observations in borderline cases. If the infant fixes objects steadily without nystagmus or squinting and responds to subtle clues-such as a silent smile or movements of small objects-the vision is unlikely to be sufficiently poor to warrant early treatment. When there is any doubt little is lost by reassessing the child after an interval of one or two weeks. In borderline cases repeated examinations may be needed to make this critical decision. Bilateral congenital cataract is the most common cause of potentially treatable blindness in infancy. Almost certainly early surgery leads to better visual results-provided that optical correction is started promptly.6 Unfortunately, delays in diagnosis and referral result in most babies with bilateral severe congenital cataracts being seen by the ophthalmologist for the first time between 2 and 4 months of age. Effects of visual deprivation must be expected by the age of 4 months, and ideally all patients should be referred early enough for surgery and optical correction to be completed, if necessary, by the age of 2 months. After surgery the baby is fitted with high gas-transfer contact lenses designed for continuous wear.7 The risk of corneal damage from these is substantial, and frequent follow-up visits are necessary. The contact lenses are not strictly necessary once the child reaches 3 years or so, when he can wear spectacles. The cost of contact lens treatment (to both the parents and the NHS) is admittedly high-perhaps between f200 and £1200 a year, depending on the numbers of lenses used and the distance from the contact lens department. Nevertheless, if the improvement in the child's visual performance is sufficient to shift him from one educational category to another such treatment is clearly cost effective. Until recently the visual prognosis for eyes with unilateral cataract was universally agreed to be so poor that surgery was indicated only for cosmetic reasons or to prevent glaucoma resulting from a "hypermature" lens. Recently Beller et a18 have described a series of children who were operated on and optically corrected within days of birth, followed by vigorous occlusion of the normal eye. Careful monitoring of the vision of both eyes by psychophysical or electrophysical means showed that nine patients who had received ideal treatment had Snellen acuities of about 6/9. The …