![]() ![]() However, it was better than the AUC measured in the 3 × 3 mm whole image macular area and the optic disc. The comparison between different areas showed that the AUC of OCTA parameters (vessel density) in the peripapillary area was equal to that of the 6 × 6 mm whole image macular area. In this paper PPG and GS eyes were combined into one group: the preglaucoma group (PrG). Glaucoma suspect (GS) eyes had glaucomatous visual field defects or glaucomatous structural defects, but none of the findings were clear enough to allow the diagnosis of glaucoma. PPG eyes had structural optic disc glaucomatous damage (rim defect, cupping, or nerve fiber layer defect) without detectable glaucomatous visual field defects. Ocular hypertension (OHT) eyes were defined as having a documented IOP > 21 mm Hg without evidence of visual or structural glaucomatous damage. There were cases of eyes with closed angles that experienced an acute primary angle closure (APAC) crisis with a fast IOP rise. Angle closure glaucoma (ACG) eyes differed from OAG eyes in that they had an occludable anterior chamber angle on gonioscopy in 3 or more quadrants. Normal tension glaucoma (NTG) eyes were similar to POAG eyes, with the difference of having an untreated IOP ≤21 mm Hg. Primary OAG (POAG) eyes were OAG eyes with an untreated intraocular pressure (IOP) > 21 mm Hg and with no structural cause for the elevated IOP. Open-angle glaucoma (OAG) eyes had an open angle on gonioscopy and they had characteristic glaucomatous visual field damage. Several types of glaucoma are discussed in this paper. It is estimated that at least a 25–35% retinal ganglion cell loss is necessary before abnormalities in automated visual field testing are detectable. Finally, in most cases, visual field testing can only detect damage after it is already recognizable in the structural exams (preperimetric glaucoma PPG). However, visual field testing remains the preferred exam type in advanced glaucoma due to the nonexistence of the floor effect that exists in OCT. This is especially important in advanced glaucoma cases, with larger fluctuations in perimetric results, rendering it difficult to define actual glaucomatous progression. However, it requires a great amount of concentration and cooperation from the patient, lowering its repeatability and reproducibility. On the other hand, visual field testing is clinically more relevant since it measures visual function. Therefore, OCT is not the best method to detect changes in advanced glaucoma. Its not being close to zero can be explained by the presence of nonneural tissue in the retinal layers that remains even in advanced cases of retinal ganglion cell loss. The exact value of this base level varies across different OCT brands and different parameters but generally lies between 50 and 70% of the nerve fiber layer thickness in normal eyes. However, there is a floor effect for OCT in advanced glaucoma, when the OCT parameters reach a base level beyond which little change is seen with increasing severity of glaucoma. OCT is not dependent on patient response and therefore provides objective information on retinal layers’ thickness, with a high repeatability and reproducibility. Both technologies have strengths and limitations. Conclusion: OCTA shows potential to become a part of everyday glaucoma management.Ĭurrently, there are 2 groups of complementary exams used for the diagnosis and follow-up of glaucoma patients: structural (where OCT has a considerable role) and functional (visual field) optic nerve measurements. Results: OCTA (1) has a high repeatability and reproducibility, (2) has good discriminatory power to differentiate normal eyes from glaucoma eyes, (3) is more strongly correlated with visual function than conventional OCT, (4) has good discriminatory power to differentiate early-glaucoma eyes from normal eyes (i.e., at least equal to that of OCT), (5) reaches a floor effect at a more advanced disease stage than OCT, and (6) is able to detect progression in glaucoma eyes. Methods: A database search was carried out using MEDLINE, Embase, and Web of Science, including all original works registered until July 23, 2017. Aims: To perform a literature review to assess the role of OCTA in glaucoma diagnosis and follow-up. However, a summary of findings is currently lacking. Despite it being a novel technique, several publications have already been done in the glaucoma field. Optical coherence tomography (OCT) angiography (OCTA) is a recently developed technique that provides a quantitative assessment of the microcirculation of the retina and choroid in a fast, noninvasive way. Several techniques exist for the diagnosis and follow-up of patients. Background: Glaucoma is the leading cause of irreversible blindness worldwide. ![]()
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