Purpose.: To investigate whether choroidal thickness measured using optical coherence tomography (OCT) in eyes with advanced glaucoma differs from that of fellow eyes with no or mild glaucoma. Methods.: Thirty-six patients with advanced glaucoma in one eye and with no glaucoma or mild glaucoma in the fellow eye underwent macular scanning using enhanced depth imaging OCT. Average, subfoveal, nasal, and temporal choroidal thicknesses were compared between severely affected and fellow eyes after adjusting for axial length and intraocular pressure. Results.: There were no significant differences between choroidal thickness measurements in eyes with advanced glaucoma and those in fellow eyes (P = 0.78 to 0.99). Based on average and subfoveal choroidal thicknesses, the choroid of eyes with advanced glaucoma was thicker than that of fellow eyes in 2.8% and 2.8% of the patients, whereas the choroid of fellow eyes was thicker than that of eyes with advanced glaucoma in 5.6% and 8.3% of the patients (P = 0.55 and 0.30, respectively). Neither eye had a consistently thinner or thicker choroid. Stepwise multiple regression analysis also showed no differences between choroidal thicknesses of severely affected eyes and those of fellow eyes (all P > 0.05). Factors associated with a thinner choroid were aging (28.6 μm per decade, P < 0.001) and increasing axial length (21.4 μm/mm, P < 0.001). Visual field mean deviation did not correlate with choroidal thickness measurements. Conclusions.: There was no significant change in choroidal thickness of eyes with advanced open-angle glaucoma compared to that of fellow eyes with no glaucoma or with mild glaucoma. A thinner choroid does not necessarily indicate the presence of glaucoma, nor is a thicker choroid necessarily a surrogate for the absence of glaucoma. These observations further suggest a lack of relationship between open-angle glaucoma and choroidal thickness.

Optical coherence tomography (OCT) has moved to the forefront of imaging modalities in the management of glaucoma and retinal diseases. It is modifying how glaucoma and glaucoma progression are diagnosed clinically and augmenting our understanding of the disease. OCT provides multiple parameters from various anatomic areas for glaucoma diagnosis, evaluation of treatment efficacy, and progression monitoring. While the use of multiple parameters has increased the likelihood of detecting early structural changes, diagnosing glaucoma in early stages is often challenging when the damages are subtle and not apparent on OCT scans, in addition to the fact that assessment of OCT parameters often yields conflicting findings. One promising approach is to combine multiple individual parameters into a composite parameter from the same test to improve diagnostic accuracy, sensitivity, and specificity. This review presents current evidence regarding the value of spectral domain OCT composite parameters in diagnosing early glaucoma.