RNFL Optical Texture Analysis May Detect Pre-Glaucoma Axonal Fiber Loss

RNFL optical texture analysis may reveal otherwise undetectable early signs of glaucoma.

Optical texture analysis may reveal signs of glaucoma not be detectable using optical coherence (OCT), retinal nerve fiber layer (RNFL) thickness analysis, or red-free RNFL photography, according to a study published in Ophthalmology. The study authors report that 10.8% of a cohort with ocular hypertension (OHT) and no signs of optic disc or RNFL thickness abnormalities who were examined with RNFL optical texture analysis (ROTA) showed change or loss in nerve fibers.

ROTA is an algorithm that measures the optical texture of axonal fiber bundles. It integrates RNFL thickness and reflectance derived from OCT to reveal the trajectory of axonal fiber bundles and show their loss of the optical texture in glaucoma.

Researchers analyzed data from 600 eyes of 306 participants (mean age, 58.2±12.9 years; mean intraocular pressure 24.9±1.8 mm Hg in the eye with worse IOP). The participants had no visual field defects or abnormal RNFL thickness on OCT scans.

Of the 37 eyes of 33 patients that exhibited RNFL defects upon RNFL optical texture analysis, 62.2% displayed alterations in the superior arcuate bundle, 27.0% at the superior papillomacular bundle, and 21.6%  the inferior papillomacular bundle. Also, 10.8% displayed papillofoveal bundle defects. These defects ranged in size from 0.0° beside the Bruch’s membrane opening margin to a width of more than 29.3°.

Loss of optical texture of the axonal fiber bundles in ROTA may represent the earliest detectable sign of glaucoma in the glaucoma continuum.

Previous trials affirmed that high IOP, age, central corneal thickness (CCT), vertical cup-to-disc ratio, and visual field PSD are all independent risk factors for glaucoma. The present study adds that individuals with OHT and RNFL defects in RNFL optical texture analysis are more likely to develop VF loss compared with individuals who do not have RNFL defects.

“By determining the pattern and region of RNFL defects, assessing the risk for VF loss, and identifying patients in danger of glaucoma progression for IOP-lowering treatment, ROTA can help personalize glaucoma treatment,” according to the study authors. “Loss of optical texture of the axonal fiber bundles in ROTA may represent the earliest detectable sign of glaucoma in the glaucoma continuum.”

This investigation did not include a control group without OHT, or measure macular GC-IPL thickness, which may represent limitations. Also, 24-2 VF pattern was performed, but not a 10-2 test.

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

References:

Kai-Ying Su C, Guo PY, Man Chan PP, et al. Retinal nerve fiber layer optical texture analysis: detecting axonal fiber bundle defects in patients with ocular hypertension. Ophthalmol. Published onlineJune 12, 2023. doi:10.1016/j.ophtha.2023.06.004