Macular SD-OCT Outcome Measures: Comparison of Local Structure-Function Relationships and Dynamic Range.
OBJECTIVE
We tested the hypothesis that the macular ganglion cell layer (GCL) thickness demonstrates a stronger structure-function (SF) relationship and extends the useful range of macular measurements compared with combined macular inner layer or full thickness.


METHODS
Ninety-eight glaucomatous eyes and eight normal eyes with macular spectral domain optical coherence tomography (SD-OCT) volume scans and 10-2 visual fields were enrolled. Inner plexiform layer (IPL), GCL, macular retinal nerve fiber layer (mRNFL), ganglion cell-inner plexiform layer (GCIPL), ganglion cell complex (GCC), and full thickness (FT) measurements were calculated for 8 × 8 arrays of 3° superpixels. Main outcome measures were local structure-function relationships between macular superpixels and corresponding sensitivities on 10-2 fields after adjusting for ganglion cell displacement, dynamic range of measurements, and the change point (total deviation value where macular parameters reached measurement floor).


RESULTS
Median (interquartile range [IQR]) mean deviation was -7.2 (-11.6 to -3.2) dB in glaucoma eyes. Strength of SF relationships was highest for GCIPL, GCL, GCC, and IPL (ρ = 0.635, 0.627, 0.621, and 0.577, respectively; P ≤ 0.046 for comparisons against GCIPL). Highest SF correlations coincided with the peak of GCL thickness, where the dynamic range was widest for FT (81.1 μm), followed by GCC (65.7 μm), GCIPL (54.9 μm), GCL (35.2 μm), mRNFL (27.5 μm), and IPL (20.9 μm). Change points were similar for all macular parameters (-7.8 to -8.9 dB).


CONCLUSIONS
GCIPL, GCL, and GCC demonstrated comparable SF relationships while FT, GCC, and GCIPL had the widest dynamic range. Measurement of GCL did not extend the range of useful structural measurements. Measuring GCL does not provide any advantage for detection of progression with current SD-OCT technology.
Glaucoma Division Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, United States 2Eye Research Center, Rasoul Akram Hospital, Iran University of Medical Sciences, Tehran, Iran.
Arezoo
A
Miraftabi
Glaucoma Division Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, United States.
Navid
N
Amini
Glaucoma Division Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, United States.
Esteban
E
Morales
Glaucoma Division Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, United States.
Sharon
S
Henry
Glaucoma Division Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, United States 3Department of Biostatistics, Jonathan and Karin Fielding School of Public Health, University of California, Los Angeles, Los Angeles, California, United States.
Fei
F
Yu
Department of Biostatistics, Jonathan and Karin Fielding School of Public Health, University of California, Los Angeles, Los Angeles, California, United States.
Abdolmonem
A
Afifi
Glaucoma Division Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, United States.
Anne L
AL
Coleman
Glaucoma Division Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, United States.
Joseph
J
Caprioli
Glaucoma Division Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, United States.
Kouros
K
Nouri-Mahdavi
D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D018450:Disease Progression; D005260:Female; D005901:Glaucoma / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D007429:Intraocular Pressure; D008266:Macula Lutea / Q000473:pathology* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000473:pathology; D012165:Retinal Ganglion Cells / Q000473:pathology*; D041623:Tomography, Optical Coherence / Q000379:methods*; D014794:Visual Fields / Q000502:physiology*