Contact lenses rest directly on the eye's tear film – which is why the glasses prescription alone is not enough. During the fitting the optometrist measures corneal curvature (keratometry), assesses tear quantity and quality and selects the material, diameter and radius of the lens accordingly. Options include soft lenses (daily, monthly or yearly) and rigid gas-permeable (hard) lenses, plus special lenses for astigmatism (toric), presbyopia (multifocal) or irregular corneas.
The process involves several steps: initial consultation and measurement, inserting a trial lens, assessing the fit at the slit lamp after a wearing period, and instruction in handling, insertion/removal and hygiene. After a few days to weeks a follow-up check usually follows, verifying fit, acuity and tolerance. Only then is the fitting considered complete.
A proper fitting matters because poorly fitting or badly maintained lenses can cause red eyes, dryness, deposits and, in the worst case, corneal infections. That is why regular follow-ups (usually yearly) and sticking to wearing times and hygiene rules are essential. Wearing lenses too long or cleaning them with water or saliva risks infection.
In Switzerland the initial fitting costs roughly CHF 80–200 depending on lens type and effort; special lenses (toric, multifocal, rigid) are higher (guide values, no guarantee). Lenses and care products are an ongoing cost – daily lenses are often more expensive per year than monthly ones. Basic insurance usually does not cover contact lenses for adults, except for certain medical indications.