I’ve just examined a 9-year-old boy and he has what looks like white/yellow exudates on his retina in his left eye. He is healthy and does not have diabetes. What is going on?

 White/yellow retinal lesions on a young retina sound like Coats’ disease to me. This is more common in males than females and most commonly discovered in children before the age of 10 years, but can present in adulthood. It is a rare condition, affecting 1 in 100,000 people. It is a telangiectatic neovascular disease of the retina of unknown cause. In other words, it is an abnormality of the retinal blood vessels. Sometimes called spider veins, they are small dilated blood vessels measuring between 0.5 and 1 mm in diameter. The abnormal blood vessels may be leaky, which means that fluid can leave the vessels, becoming trapped within, and sometimes underneath, the retina causing it to lift up – leading to an exudative retinal detachment. The leaked fluid gives rise to the appearance of white/yellow retinal exudates.

It is possible for Coats disease to affect both eyes, but in over 90 per cent of cases, it is unilateral. If Coats’ disease affects the macula or leads to a total retinal detachment in the affected eye, vision in this eye can be permanently lost.

Laser treatment can be used to seal up the leaky blood vessels. In addition, any areas of the retina that are shown on fundus fluorescein angiogram to have lost their normal blood supply will also be lasered. This is to prevent further leakage and also the growth of more abnormal vessels (neovascularisation) that can occur in areas of ischaemic retina.

Anti-VEGF injections into the vitreous (similar to those used in wet age-related macular degeneration) can also reduce abnormal leakage and blood vessel growth.

One of the challenges of this condition is that the white/yellow exudates may appear in those parts of the retina not easily visualised during direct ophthalmoscopy when looking through a non-dilated pupil. Visual acuity may be normal in those patients without macular involvement and there is nothing to alert the eye specialist to a problem so the pupils aren’t dilated.

The patient needs to be referred to an eye specialist with expertise in managing retinal problems.