Glaucomatous Damage Can Best Be Detected With OCT Performed Twice Per Year

Undergoing optical coherence tomography (OCT) or OCT-angiography (OCT-A) scans twice per year can help clinicians reduce the time needed to detect glaucoma progression, according to research published in the American Journal of Ophthalmology. Both circumpapillary retinal nerve fiber layer (cpRNFL) thinning and circumpapillary capillary density (cpCD) reduction are equally useful metrics for determining this progression. 

Researchers performed a longitudinal analysis of 98 patients with primary open-angle glaucoma (POAG; eyes, 156; mean age, 68.6 years) from the Diagnostic Innovations in Glaucoma Study (DIGS; ClinicalTrials.gov Identifier: NCT00221897) to assess how the frequency of OCT and OCT-A scans affect the time needed to detect glaucoma progression. Study participants had a total of 4 or more OCT and OCT-A scans taken over a mean 3.5 year period. Longitudinal cpRNFL thickness and cpCD changes were measured using these scans, and a computer simulation determined the time needed to detect progression for different loss rates and testing frequencies.

The time required to detect cpCD progression and cpRNFL change were similar across different rates of loss and decreased as testing frequency increased, study authors report. When testing was performed once per year, 80% of eyes with cpCD loss of 1% per year were identified after 6.0 years. The time to identify progression in these patients was reduced to 4.2 years with 2 scans, and 4.0 years with 3 scans.  

Using cpRNFL as a metric to identify glaucomatous damage, 80% of eyes with cpRNFL loss of 1 µm per year were identified after 6.3 years with 1 scan per year. The time to identify progression was reduced to 5.0 years with 2 scans and 4.2 years with 3 scans. The trend indicates that an increase in scans decreases the time to detect glaucomatous structural damage, but the change in time for detecting damage is not significant after 2 scans. Researchers suggest that 2 visits per year are adequate for reducing diagnostic time. 

“We found that cpRNFL and cpCD are comparable for the detection of progression,” according to the researchers. “Further, this study showed that increasing the number of tests from two to three does not reduce the time required to detect progression. Two visits per year appear sufficient for detecting glaucoma using both cpRNFL and cpCD.”

Study limitations include a limited sample size and the exclusion of poor quality scans. 

Disclosure: This research was supported by multiple sources. Several study authors declared affiliations with biotech, pharmaceutical, and/or clinical research organizations. Please see the original reference for a full list of authors’ disclosures.