Dr Moïse Tourabaly · Key points
A monofocal implant concentrates all the light on a single focal point. A multifocal or EDOF implant shares it between several focal points, to see clearly at several distances: each one receives only a fraction, and the image loses contrast.
With a monofocal, contrast is preserved: this is the reference. Clear distance vision; glasses for reading.
In a healthy eye, the retina absorbs this compromise and the patient adapts. When the macula (AMD, membrane, oedema) or the optic nerve (advanced glaucoma) has already used up part of its reserve, the multifocal's loss of contrast adds to it: the hoped-for comfort may not materialise. An EDOF also shares light, somewhat less.
There is no absolute contraindication: very early, stable AMD or early, well-controlled glaucoma are discussed case by case, after a macular OCT and an examination of the optic nerve. A monofocal, toric if needed, is not a consolation prize: it protects the remaining quality of vision. Proportions are illustrative.
Educational diagram · Dr Moïse Tourabaly, ophthalmologist. It does not replace a consultation.