Electrodiagnosis: Achieving objective

Measurements of retinal ganglion cell (RGC) complex and retinal nerve fibre layer (RNFL) thicknesses are important in the diagnosis and management of glaucoma. Use of the OCT has played an important role in making these measurements available, and there are a number of algorithms that identify change and progression in order to identify glaucomatous damage to ganglion cells or thinning of the RNFL.

However, by the time significant measurable loss of RGC occurs, and therefore glaucomatous optic neuropathy can be diagnosed, irreversible visual functional loss will have occurred. This in turn may result in permanent field loss (figure 1).

Therefore, using current diagnostic methodology, treatment may only commence when up to 80% of RGC have already disappeared. How useful therefore would be a diagnostic test that identifies glaucomatous RGC damage before cell death and therefore permanent functional loss occurs?