Effectiveness of optical coherence tomography angiography (OCT-A)‎ in staging glaucoma

الملخص EN

Objectives: To analyze whether vessel density or nerve fiber layer thicknes (structural properties) obtained by optical coherence tomography angiography (OCT-A) could differentiate between healthy controls and patients with ocular hypertension or mild, moderate and severe glaucoma.

In addition, to determine if vessel density or nerve fiber layer thickness is most helpful in detecting early glaucomatous damage.

Methods: In this retrospective study, we selected 69 healthy controls, 36 patients with ocular hypertension, and 91 with primary open-angle glaucoma (54 mild, 25 moderate, and 12 severe).

One eye was randomly selected per patient.

Patients were excluded if they were < 18 years, had secondary glaucoma, OCT-A signal strength index < 40, refractive errors > ± 5 D, vision worse than 20/40, or only one functional eye.

Collected data included: age, ethnicity, gender, family history of glaucoma, intraocular pressure, visual fields, cup/disc ratio, and OCT-A macular and optic nerve head scanning parameters.

Results: Whole image optic nerve head and macular vessel density both decreased as the glaucoma progressed, from ocular hypertension to severe stage, 56.7% to 43.1% and 49.0% to 43.4%, respectively (p<0.01).

Similarly, average nerve fiber layer thickness decreased from, 92.0μm to 60.1μm (p<0.01) in patients with ocular hypertension to those with severe glaucoma.

Both structural properties and vessel density were equally effective at determining glaucoma stage.

Between healthy controls and patients with ocular hypertension, we noticed structural property differences, but no vessel density differences.

Conclusion: Both optic nerve head and macular vessel density and structural properties assessed by OCT-A may provide an objective measure of glaucomatous damage in the eye.

In addition, we have found that structural damage may occur before vessel density damage in ocular hypertension.