Optical coherence tomography, an important new tool in the investigation of the retina

Optical coherence tomography, an important new tool in the investigation ofthe retina Recently optical coherence tomography (OCT) has been introduced into the field of ophthalmology to enhance visualization ofthe various retinal layers. OCT uses interference of near infra-red, low-coherent light reflected from the retina and from a reference mirror, to create transverse sections of the retina. The strength of the signal is a measure of the reflection of the retinal layer which is situated at the same distance from the light source as the mirror. Accurate placement ofthe mirror gives a transverse view of the retina with an axial resolution of 10 microm, with which the resolution of a histological section can be approximated. OCT is used in ophthalmic diseases such as macular oedema, macular holes and other abnormalities on the retinal-vitreous border, following photodynamic therapy and in treating glaucoma. OCT has been used to detect early glaucoma by measuring the thickness of the retinal nerve fibre layer. OCT and fluorescence angiography complement one another as diagnostic methods but OCT is superior in the diagnosis of macular oedema and macular holes. OCT provides images of retinal pathology which can easily be interpreted by both ophthalmologists and patients.