Ellipsoid Zone Attenuation Predictive of Geographic Atrophy Growth

Ellipsoid zone attenuation, either partial or total, can affect the rate of geographic atrophy (GA) growth, according to data presented at the American Society of Retina Specialists meeting, held in Seattle, July 28 to August 1, 2023. A faster GA expansion rate appears linked with greater baseline ellipsoid zone (EZ) attenuation, the report shows.    

“This highlights that EZ loss is associated with future GA expansion risk,” the presenter explained.

Researcher Reem Amine, MD, a research fellow at Cleveland Clinic, presented the team’s analysis of placebo treated participants from the ReCLAIM-2 clinical trial (ClinicalTrials.gov Identifier: NCT03891875), a phase 2 prospective, placebo-controlled evaluation of elamipretide in advanced age-related macular degeneration (AMD) with GA. 

The study used machine learning and a retinal segmentation platform to analyze ellipsoid zone integrity and GA measurements from spectral domain optical coherence tomography (SD-OCT) imaging of placebo group participants (n=38) who completed the 48^th week visit and had sufficient OCT scans. Researchers compared the GA growth that patients in the 25^th percentile and 75^th percentile groups of EZ integrity experienced from baseline through 48 weeks.

The thickness of the retinal pigment epithelium throughout the macula measured ellipsoid zone integrity at baseline. The panmacular burden is a portion of the macula.

The total loss of the RPE in retinal atrophy indicated GA on the scans. An expert reader checked and corrected B-scans for segmentation accuracy. 

The 25^th percentile group’s mean baseline percentage area was 15.4% for partial ellipsoid zone attenuation (≤20 µm) and 9.0% for total ellipsoid zone attenuation (0 µm). The 75^th percentile group had a mean baseline percentage area of 33.2% for partial ellipsoid zone attenuation and 23.2% for total ellipsoid zone attenuation. 

High attenuation groups’ percentage increase in macular GA coverage with total RPE attenuation was more than triple that of the low attenuation groups (5.1-5.3% vs 1.4-1.5%, respectively, of absolute increase in macular GA coverage P <.001), according to the poster.

“[Ellipsoid zone] loss and quantification as an important potential AMD endpoint and potential enrichment tool for clinical trial design,” Dr Amine explained.

Disclosure: Some of the study authors declared affiliations with the biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.