OCT-A in practice part 6: glaucoma

After 30 years of seeing patients with glaucoma I have redefined glaucoma as ‘distress followed by loss of ganglion cells and thinning of the retinal nerve fibre layer culminating in a loss of visual field’. Primary open angle glaucoma is characterised by one or more of the following disc changes:

Distress of ganglion cells is measurable by pattern ERG (I use the Diopsys system) which measures the electrical activity of retinal ganglion cells and, if picked up early enough, could prevent death of the ganglion cells. Loss of ganglion cells is measurable using OCT and, since the macula area contains around half of the retinal ganglion cells, it is best to concentrate on the superior and inferior ganglion cell complex (GCC) at the macula.