Structural evaluation of preperimetric and perimetric glaucoma

Area of Science:

• Ophthalmology
• Medical Imaging
• Glaucoma Diagnostics

Background:

• Glaucoma diagnosis relies on detecting structural changes in the optic nerve head and macula.
• Macular ganglion cell-inner plexiform layer (GCL-IPL) and peripapillary retinal nerve fiber layer (RNFL) are key indicators of glaucomatous damage.
• Evaluating the diagnostic efficacy of these parameters is crucial for early detection and management of glaucoma.

Purpose of the Study:

• To assess the diagnostic capability of macular GCL-IPL for identifying preperimetric glaucoma (PPG) and perimetric glaucoma.
• To compare the diagnostic performance of GCL-IPL parameters with peripapillary RNFL thickness.
• To determine which imaging modality offers superior detection of early and established glaucoma.

Main Methods:

• A study involving 337 eyes from 190 patients (127 normal, 70 PPG, 140 perimetric glaucoma).
• Ocular evaluation, standard automated perimetry, and spectral domain optical coherence tomography (SD-OCT) were performed.
• Diagnostic abilities were quantified using area under the curve (AUC), sensitivity, and specificity.

Main Results:

• RNFL thickness demonstrated higher diagnostic accuracy than GCL-IPL for both PPG and perimetric glaucoma.
• Inferior RNFL thickness showed the highest AUC (0.922) for discriminating normal eyes from primary open-angle glaucoma (POAG).
• While RNFL performed better, the observed differences in diagnostic ability between RNFL and GCL-IPL were small.

Conclusions:

• Peripapillary RNFL thickness offers superior diagnostic performance compared to macular GCL-IPL for detecting glaucoma.
• The diagnostic advantage of RNFL over GCL-IPL, while statistically significant, may not hold substantial clinical relevance.
• Both imaging techniques are valuable, but RNFL may be preferred for its slightly higher sensitivity and specificity in glaucoma detection.