Increasing sampling density improves reproducibility of optical coherence tomography measurements

Area of Science:

• Ophthalmology
• Medical Imaging
• Glaucoma Research

Background:

• Peripapillary retinal nerve fiber layer (RNFL) thickness is a key indicator in glaucoma diagnosis.
• Current optical coherence tomography (OCT) measurements use a standard sampling density of 100 points per quadrant.

Purpose of the Study:

• To evaluate if a four-fold increase in OCT sampling density enhances the reproducibility of peripapillary RNFL measurements.
• To compare RNFL thickness and variability between standard and increased sampling densities.

Main Methods:

• Ophthalmic examinations, automated perimetry, and OCT imaging were conducted.
• OCT scans included quadrantic (100 points/quadrant) and circular (25 points/quadrant) sampling.
• RNFL thickness and coefficient of variation (CV) were calculated for superior and inferior quadrants.

Main Results:

• RNFL thickness was thinner in quadrants with visual field defects for both 25- and 100-points/quadrant scans.
• No significant difference in mean RNFL thickness or CV was observed for normal quadrants between sampling densities.
• Quadrants with visual field defects showed thinner RNFL measurements with 25-points/quadrant scans compared to 100-points/quadrant scans.
• The CV was significantly higher for 25-points/quadrant scans (25.9%) than for 100-points/quadrant scans (11.9%).

Conclusions:

• Increased OCT sampling density provides a more reproducible measure of peripapillary RNFL thickness.
• Higher sampling density reduces variability in RNFL measurements, particularly in glaucomatous eyes.
• The optimal OCT sampling density for maximal measurement reliability requires further investigation.