Early Glaucoma Can Be Diagnosed Based On Single Structure Abnormalities

In both pre-perimetric and early perimetric glaucoma, the diagnostic agreements between the optic nerve head (ONH), retinal nerve fiber layer (RNFL), and ganglion cell-inner plexiform layer (GCIPL) parameters based on high-definition optical coherence tomography (HD-OCT) normative database classification were mostly fair, according to research published in the Journal of Glaucoma. The findings suggest clinicians should not wait for multiple structures to show abnormality on OCT to diagnose early glaucoma.

Researchers conducted a retrospective cross-sectional study to evaluate the agreement of normative database diagnostic classification between ONH, RNFL, and GCIPL in patients with early glaucoma. They used normative database diagnostic classifications from HD-OCT scans of 1 eye per participant and assessed agreement between abnormal classifications by single and combined structural parameters. For single parameters, they classified an eye as abnormal if any of the optic disc, RNFL, or GCIPL was abnormal. For combined parameters, they required eyes to be flagged as abnormal by both classifications (global or sectorial). 

The study included a total of 163 eyes of 163 patients (50.3% men and 49.7% women), with a mean age of 66.4±12.3 years, 66 eyes of 66 patients with pre-perimetric glaucoma and 97 eyes of 97 patients with early perimetric glaucoma. 

They found the agreements between RNFL and GCIPL were fair in both pre-perimetric (κ=0.25) and perimetric glaucoma (κ=0.21) and between RNFL or GCIPL and ONH parameters (rim area and vertical cup-to-disc ratio; VCDR) were inconclusive due to insufficient data. 

They found combining GCIPL and rim area yielded fair agreement with RNFL both in pre-perimetric (κ=0.21) and perimetric glaucoma (κ=0.33) and a moderate agreement between RNFL-rim area versus VCDR (κ=0.48 in pre-perimetric glaucoma; κ=0.45 in perimetric glaucoma). 

“Practically, treatment should be initiated without waiting for damage to be detected in all 3 structures,” the study authors recommend. “Despite little evidence to guide therapeutic decisions for patients with pre-perimetric glaucoma, treatment should be initiated mostly considering the risk of progression. For instance, glaucoma suspects enrolled in the Diagnostic Innovation in Glaucoma Study (DIGS) had a four-fold increased risk of developing perimetric disease during follow-up if they had RNFL thinning at baseline.”

Limitations of the study included lack of analysis of RNFL clock-hour performance, use of a single OCT platform, and potential inclusion of patients with eyes falsely classified as abnormal due to their values being closer to the lower limit of the normal range.

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