[Summary of the practice guideline 'Refraction errors' from the Dutch College of General Practitioners]

The practice guideline 'Refraction errors' from the Dutch College of General Practitioners describes the examinations that need to be carried out in patients complaining about a gradual loss of vision. A measurement of vision by means of a Snellen chart is insufficient to determine if the condition is caused by a refraction error or if other pathology of the eye such as cataract, glaucoma or retinopathy is involved. It is therefore recommended that the vision should also be measured with a simple device containing spherical lenses of +0.5 and -0.5 dioptre, so-called diagnostic refraction. Improvement of vision with the negative lens indicates myopia. Improvement or at least a stable vision with the positive lens makes hyperopia very likely. Diagnostic refraction, which can be used in patients of six years and older, enables the general practitioner to distinguish between patients needing glasses or contact lenses, and patients requiring referral to an ophthalmologist.