Optical coherence tomography angiography (OCTA) could play a growing role in the assessment of anterior inflammation from uveitis, according to results from a pilot study presented by Francesco Pichi, MD.
Uveitis has not had as many imaging advances as other areas of ophthalmology, such as in retinal disease, said Dr. Pichi, Cleveland Clinic, Abu Dhabi, and assistant professor of ophthalmology, Cleveland Clinic Lerner School of Medicine, Case Western University, Cleveland. However, anterior uveitis begins in the vessels of the iris and now, with OCTA, uveitis specialists have a less-invasive technology that can track the movement of red blood cells.
In the study led by Dr. Pichi, 50 patients with anterior acute uveitis with 1+ to 4+ cells were included. If there was bilateral uveitis, the eye with the highest cell count was included. Patients’ irises were scanned with OCTA at baseline and at 7 and 14 days. Patients were treated with topical prednisolone drops.
As this was a pilot study, researchers also created a control group with 30 undilated healthy patients who had no vascular pathology. These healthy irises were scanned with OCTA at one time point. The scanning method used was 3×3 mm square centered on the nasal and temporal iris, with the focus increased to +20 D to have the iris tissue within the scanning depth of a machine that is built to look at the retina.
When assessing results from normal patients, researchers could not see the iris vessels that clearly because of fibrin bands in the stroma.
“Everything changed when we scanned the uveitis patients,” Dr. Pichi said. “When you have anterior uveitis, there’s an increased flow in the vessels in the iris. It is so well-lighted, we can study the anatomy.”
Although researchers could potentially assess the images to measure the effectiveness of treatment, that was not the study’s purpose. So, Dr. Pichi and co-researchers at Cole Eye Institute created an algorithm and a 3-D rendering of the iris to evaluate the volume of the blood vessels in various portions of the iris.
Researchers were able to see with the results that the volume of the blood in specific parts of the iris increased as inflammation increased.
“With the treatment with steroids, there was a progressive decrease at 15 days in volume measurements,” Dr. Pichi said.
Dr. Pichi and co-researchers took things a step further by focusing on 20 patients with anterior uveitis and performing a 6-×6-mm OCTA of the iris, and combining the iris vessels volume measurements thus obtained with the automated count of cells in the anterior chamber through spectral-domain OCT.
These two algorithms for OCT and OCTA provide a number of inflammatory cells and a volume of blood flow in the iris, to quantify anterior uveitis. Study limitations included a lack of eye tracking, no control of the pupil, and possible vasoconstriction due to steroid use. However, the study’s strengths included prediction, measurements, and correlation.
“It’s a first step, and in the future, we’ll be able to include these things in clinical trials,” he said.
FRANCESCO PICHI, MD
E: [email protected]
This article was adapted from Dr. Pichi’s presentation at the 2017 meeting of the American Academy of Ophthalmology. Dr. Pichi has no related disclosures.