Corneal disease
How is it diagnosed?
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| Topographical Orbscan® corneal maps |
Corneal disease is diagnosed by observing and analysing the cornea with specialised equipment.
Corneal imaging
Many techniques are used to examine the cornea. These include:
- Slit lamp biomicroscopy
- Orbscan® topography
- Pachymetry
- Specular microscopy
Slit lamp biomicroscopy
The slit lamp is a high powered microscope that is used to examine and photograph the living tissues of the eye.
Most corneal disease is first diagnosed by observation at the slit lamp. Detection and diagnosis of disease may be aided by the use of dyes such as fluorescein which stain the tears and highlight changes in the corneal surface.
Orbscan®
Individual endothelial cells imaged by the specular microscope.
The Orbscan® is an instrument that provides a surface 'map' of the cornea, in much the same way a topographic map represents a geographical landscape.
Orbscan analyses both the overall shape of the cornea and local variations.
Pachymetry
Measurement of the thickness of the cornea is known as pachymetry. Corneal thickness is assessed by either ultrasound or an optical probe.
Specular microscopy
This photographic technique images the endothelium, the single layer of cells on the inner surface of the cornea. Details of the size, shape and density of cells are obtained.
Specular microscopy plays a key role in decision making in some corneal diseases. Dr McKellar purchased the first specular microscope in private practice in New Zealand.