Corneal Diameter

Synonyms

White-to-white distance

Definition

Horizontal measurement across the cornea.

Structure

At birth, a normal human cornea measures 10 mm in horizontal diameter, whereas the size of a normal adult cornea measures approximately 12 mm horizontally, practically always exceeding the vertical diameter. Adult corneal diameter is reached at 2 years of age (Velazquez 2005; Friedman 2007).

Function

To rule out disorders associated with anomalies of the size and shape of the cornea such as buphthalmos in children and to assess biometrical parameters of the anterior chamber prior to intraocular surgery.

Measurements can be performed with a variety of devices such as partial coherence laser interferometry or optical coherence tomography.

Clinical Relevance

Corneal diameter measurements are of importance in disorders such as microcornea, megalocornea, buphthalmos, and other corneal dystrophies.

Preoperative WTW distance is required in choosing an intraocular lens (IOL), as the calculation of...