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Retinal nerve fiber layer reflectance for early glaucoma diagnosis
Shuang Liu1, Bingqing Wang, Biwei Yin
1Departments of *Biomedical Engineering †Electrical & Computer Engineering, The University of Texas at Austin, Austin, TX ‡Imaging Physics, MD Anderson Cancer Center, The University of Texas, Houston, TX §Departments of Ophthalmology and Neurobiology, Duke University Medical Center, Durham, NC.
Normalized reflectance index (NRI) shows promise for detecting early glaucoma, outperforming retinal nerve fiber layer thickness (RNFLT) in identifying glaucoma suspects. Further research is needed to confirm its diagnostic value.
Area of Science:
- Ophthalmology
- Medical Imaging
- Diagnostic Technologies
Background:
- Glaucoma diagnosis relies on detecting structural and functional changes.
- Optical coherence tomography (OCT) is crucial for imaging the retina.
- Retinal nerve fiber layer thickness (RNFLT) is a common OCT metric, but early detection remains challenging.
Purpose of the Study:
- To compare the diagnostic performance of normalized reflectance index (NRI) and RNFLT from OCT images.
- To evaluate these parameters for distinguishing between healthy, glaucoma suspect, and glaucomatous eyes.
Main Methods:
- Seventy-five eyes from 71 subjects (33 control, 24 glaucoma, 18 glaucoma suspect) were analyzed.
- RNFLT and NRI maps were acquired using two custom OCT systems and a commercial RTVue OCT.
- Area under the receiver operating characteristic curve (AUC) was used to assess diagnostic performance.
Main Results:
- Mean NRI was significantly higher in controls than in glaucoma or glaucoma suspect groups across most locations and OCT systems.
- NRI demonstrated superior performance over RNFLT in differentiating glaucoma-suspect from control eyes using RTVue OCT (P=0.008).
- No statistically significant difference was found between NRI and RNFLT for classifying glaucoma-suspect vs. control eyes with PS-OCT systems, or for classifying glaucomatous vs. control eyes across all OCT systems.
Conclusions:
- Normalized reflectance index (NRI) is a promising biomarker for identifying glaucoma suspects and potentially detecting preperimetric glaucoma.
- This pilot study suggests NRI's potential in diagnosing early-stage glaucoma.
- Larger studies are warranted to validate the diagnostic accuracy of NRI for preperimetric glaucoma.
