Alpha Omega Alpha Honor Medical Society

Glaucoma Diagnostic Capability of Global and Regional Measurements of Isolated Ganglion Cell Layer and Inner Plexiform Layer

Investigator: Jason Chien

Mentor: Sung Chul Park, MD

Objective:
To compare the glaucoma diagnostic capability of different macular layer volume and regional thickness parameters in different-sized grids.

Design:
Prospective, cross-sectional, observational study.

Participants:
69 normal eyes (69 subjects) and 87 glaucomatous eyes (87 patients) with a range of glaucomatous damage.

Methods:
Serial horizontal spectral-domain optical coherence tomography (OCT) scans of the macula were obtained. Automated grids centered on the fovea with diameters of 3, 3.45, and 6 mm were used. For each grid, 10 parameters (total volume and average thicknesses in 9 regions) were obtained for 5 layers: macular retinal nerve fiber layer (mRNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), ganglion cell-inner plexiform layer (GCIPL; GCL+IPL), and ganglion cell complex (GCC; mRNFL+GCL+IPL).

Main Outcome Measures:
Area under the receiver operating characteristic curve (AUC) of each parameter for 5 layers.

Results:
Mean age was 54±18 years in normal subjects and 58±15 years in glaucoma patients (P=0.09). For the total volume parameter, the AUCs in 6-mm grid were larger than the AUCs in 3- and 3.45-mm grids for all 5 layers. For the average thickness parameters, the best AUCs in 6-mm grid were greater than the best AUCs in 3- and 3.45-mm grids for all 5 layers. In the 6-mm grid, GCL and GCC had the greatest AUCs for the total volume parameter (AUCs = 0.920 for GCL and GCC) and for the average thickness parameters (AUCs = 0.942 for GCL in T2 [outer temporal] region and for GCC in I2 [outer inferior] region). In the 6-mm grid, IPL had good diagnostic capability for glaucoma (AUC of total volume = 0.887; AUC of average thickness = 0.890 in T2 region). GCL, IPL, and GCIPL had the greatest AUCs in T2 region; GCC and mRNFL had the greatest AUCs in I2 region.

Conclusion:
Macular GCL is at least as good as GCC and GCIPL. Macular IPL may have future roles in glaucoma diagnosis. Larger macular grids are generally better at detecting glaucoma. Each layer has a characteristic region with the best glaucoma diagnostic capability. Future investigation is needed to develop an optimal grid(s) for detecting glaucoma.

Last modified: 2/03/2017

Updated on February 3, 2017.


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