Reproducibility of macular thickness and volume using Zeiss optical coherence tomography in patients with diabetic macular edema.
OBJECTIVE
To evaluate optical coherence tomography (OCT) reproducibility in patients with diabetic macular edema (DME).


METHODS
Prospective 1-day observational study.


METHODS
Two hundred twelve eyes of 107 patients with DME involving the macular center by clinical examination and OCT central subfield thickness of > or =225 microm.


METHODS
Retinal thickness was measured with the OCT3 system, and scans were evaluated by a reading center. Reproducibility of retinal thickness measurements was assessed, and 95% confidence intervals (CIs) for a change in thickness were estimated.


METHODS
Reproducibility of OCT-measured central subfield thickness.


RESULTS
Reproducibility was better for central subfield thickness than for center point thickness (half-width of the 95% CI for absolute change, 38 microm vs. 50 microm, and for relative change, 11% vs. 17%, respectively; P<0.001). The median absolute difference between replicate measurements of the central subfield was 7 microm (2%). Half-widths of the 95% CI for a change in central subfield thickness were 22, 23, 33, and 56 microm for scans with central subfield thicknesses of <200, 200 to <250, 250 to <400, and > or =400 microm, respectively. When expressed as percentage differences between 2 measurements, half-widths of the 95% CI for a change in central subfield thickness were 10%, 10%, 10%, and 13% for scans with central subfield thicknesses of <200, 200 to <250, 250 to <400, and > or =400 microm, respectively. We were unable to identify an effect on reproducibility of central subfield measurements with respect to the presence of cystoid abnormalities, subretinal fluid, vitreomacular traction, or reduced visual acuity. Reproducibility was better when both scans had a standard deviation (SD) of the center point of <10.0% (half-width of the 95% CI for change, 33 microm vs. 56 microm; P<0.001).


CONCLUSIONS
Reproducibility is better for central subfield thickness measurements than for center point measurements, and variability is less with retinal thickness when expressed as a percent change than when expressed as an absolute change. A change in central subfield thickness exceeding 11% is likely to be real. Scans with an SD of the center point of > or =10.0% are less reproducible and should be viewed with caution when assessing the validity of an observed change in retinal thickness in patients with DME.
Jaeb Center for Health Research, 15310 Amberly Drive, Suite 350, Tampa, FL 33647, USA.
Krzystolik
Magdalena G
MG
Strauber
Samara F
SF
Aiello
Lloyd Paul
LP
Beck
Roy W
RW
Berger
Brian B
BB
Bressler
Neil M
NM
Browning
David J
DJ
Chambers
Robert B
RB
Danis
Ronald P
RP
Davis
Matthew D
MD
Glassman
Adam R
AR
Gonzalez
Victor H
VH
Greenberg
Paul B
PB
Gross
Jeffrey G
JG
Kim
Judy E
JE
Kollman
Craig
C
D003922:Diabetes Mellitus, Type 1 / Q000150:complications; D003924:Diabetes Mellitus, Type 2 / Q000150:complications; D003930:Diabetic Retinopathy / Q000175:diagnosis*; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D008266:Macula Lutea / Q000473:pathology*; D008269:Macular Edema / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011446:Prospective Studies; D015203:Reproducibility of Results; D041623:Tomography, Optical Coherence / Q000592:standards*
D006442:Glycated Hemoglobin