Glaucoma progression analysis by Spectral-Domain Optical Coherence Tomography (SD-OCT)

Spectral domain optical coherence tomography (SD-OCT) provides an objective quantification of the lesions of various target tissue structures in glaucoma, with unprecedented resolution, which has now demonstrated its interest in controlling the progression of glaucomatous neuropathy, from early stages to late stages. A certain number of well-established proofs state that a progressive modification in OCT is a common predictor of functional loss, and that patients with rapid OCT changes have an increased risk of developing glaucomatous scotoma. Follow-up of the progression goes through three stages. It consists first of all in detecting the evolution of damage to the retinal nerve fiber layer (RNFL), then that of the macular ganglion cell complex (GCC), in order to better define this progression of the damage to the target structures and, thirdly, to complete its analysis by integrating it with the analysis of the functional impairment. We note today that there is a greater risk of developing a future functional deficit of the visual field in subjects with a RNFL loss slope greater than -1/year, for all clinical stages of glaucoma. The characteristics of GCC progression are much better specified. Often earlier than that of the progress of the thinning of the RNFL and much faster in the subjects considered as "progressors", its cartography is better defined, with a particular interest for the follow-up of diversion maps and "wide field" acquisitions offering better visibility of deficits and their progression. To date, a certain number of suspicious indicators of short-term progress can be retained, highlighting the essential precaution of having two or more basic measures and a confirmation of the change on at least one new OCT acquisition. Finally, if the interpretation of the progression must always be based on clinical examination data, and the macula in particular, it remains crucial to confront the progression of the RNFL with that of the GCC and with that of the visual field.