Diabetes: how often should you have a dilated eye examination?

A diabetic patient with perfect vision can already have established retinopathy. That sentence sums up what screening is about: having no symptoms is not reassuring information, it is an absence of information.

What diabetes does to the retina

Diabetes damages small blood vessels, and those of the retina are among the finest in the body. The result is microaneurysms, then haemorrhages and, at an advanced stage, the growth of abnormal, fragile vessels that can bleed into the vitreous or cause a detachment.

On top of this comes macular oedema, a swelling of the centre of the retina. It is the leading cause of reduced vision in diabetic patients and can occur at any stage, including early on.

How often to be checked

Every two years if the diabetes is well controlled, with no retinopathy found and no associated risk factor. A dilated eye examination or retinal photography is enough.

Every year as soon as there is any retinopathy, even minimal, or if the diabetes is poorly controlled, or if there is associated high blood pressure.

More often in three situations worth knowing about:

• Pregnancy. Retinopathy can appear or worsen quickly. An examination is needed before conception if possible, then every trimester.
• Rapid intensification of treatment. Bringing blood sugar back to normal too abruptly can, paradoxically, temporarily worsen existing retinopathy. A check is warranted before and during this period.
• Type 1 diabetes diagnosed in childhood, from puberty onwards.

What this changes if you need surgery

If cataract surgery is being considered (it comes earlier in diabetic patients), the state of the retina must be known beforehand. Active retinopathy must be treated first, as surgery can make it worse. Macular oedema must be stabilised, otherwise vision will not improve despite a perfectly performed operation.

That is a disappointment we can avoid by informing the patient beforehand, rather than discovering it together afterwards.

What is still underestimated

The first treatment for retinopathy is not an eye treatment: it is good control of diabetes and blood pressure. No laser and no injection can make up for poorly controlled diabetes in the long run.

Eye treatments exist and they work: intravitreal injections for macular oedema, panretinal laser for proliferative forms, vitreoretinal surgery for complications. But they act on damage that has already been done. A regular dilated eye examination is still the only step that makes it possible to act before.

Sources Haute Autorité de Santé (French National Authority for Health), dépistage de la rétinopathie diabétique, recommandations.
Société Francophone du Diabète et Société Française d'Ophtalmologie (French-speaking diabetes society and French ophthalmology society), référentiel commun.
Assurance Maladie (French national health insurance), programme de dépistage de la rétinopathie diabétique.