The use of contact lenses as an alternative to spectacles has become very common.
However, the prescription for contact lenses can be very opaque to the uninitiated and sometimes difficult to understand.
Amongst the key data, the curve base is an essential element of the contact lens design.
Contact lenses can take different forms, according to the visual desorder to be corrected and to the eye shape.
Indeed, if its corrective power is essential, the lens is also defined by its design.
Rigid or solid and made of different materials, a contact lens has a curve specific to its future ocular support.
The convexity of the back surface of the contact lens is called base curve and constitutes its specific shape.
This studied curvature is perfectly adapted to the natural curve of the eye it will cover.
The base curve of the contact lens is specified on the prescription written by the ophthalmologist.
Noted in millimetres, it is generally qualified as flat, median or steep according to the case.
To simplify the idea, it can be said that the higher the base curve, the flatter the ocular cornea.
Most contact lenses have a base curve ranging between 8 and 10 millimetres.
Not all lenses are created equal and can correct all visual impairments indifferently.
The base curve of the lens is chosen precisely according to the shape of the eye holder.
To do this, the optician adapts the curve of the lens according to the ophthalmological results obtained after a complete visual assessment.
The contact lens base curvature is measured by the ophthalmologist with a keratograph or an opthalmometer.
This perfect adaptation to the eye shape with a specific contact lens base curve allows for clear vision.
The contact lens must indeed perfectly cover the cornea to protect it and allow a complete visual correction.
A base curve that is perfectly adapted to the natural shape of the eye also ensures optimal wearing comfort.
On the other hand, a curvature that is poorly adapted to the eye can cause real discomfort, or even an obstacle to good visual correction.
Together with the diameter, the curve base is one of the most important features of a contact lens.
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