Abstract
Purpose :
Measurements of retinal layer thicknesses with Optical Coherence Tomography (OCT) are used increasingly often in clinical routine. Thus, assessments need to be as precise as possible. Lens opacification reportedly influences OCT derived retinal nerve fiber layer thickness (RNFLT) measurements. However, with recent improvements in OCT scanning and scan overlay at follow up, this might not hold true. Against this background the purpose of this study was to determine the influence of objectively determined lens opacification on SD-OCT measurements.
Methods :
We enrolled 60 patients undergoing routine cataract surgery and assessed RNFLT and BMO parameters with SD-OCT (Spectralis, Heidelberg Engineering) one day before and one day after surgery. Accurate placement of the OCT scan at follow-up was performed using the Anatomic Positioning System (APS). This inbuilt device software recognizes individual anatomic landmarks and provides exact alignment at follow-up. Lens opacification was determined objectively with the Pentacam densitometry module using 25 Scheimpflug photographies (Pentacam AXL, Oculus GmbH).
Results :
SD-OCT data was eligible in 59 (29 female) patients, mean age was 73±8.9 years. The mean differences in the RNFLT scans were 0µm (95% Confidence Interval -1.16; 1.16), -0.34µm (95% CI -1.30; 0.61) and -0.13µm (95% CI -1.22; 0.96) and none was statistically significant. The same was true for the differences in BMO and quality parameters. Average percentage of lens opacification was 13.14% (95% CI 12.56; 13.75).
Conclusions :
Our data show no significant changes for any of the SD-OCT parameters. The percentage of lens opacification was comparable to that in similar studies. Our results challenge the previously described artificial alterations due to cataract. We hypothesize that the use of the APS prevented misplacement of the scans at follow-up. We conclude that cataract does not have a clinically relevant impact on SD-OCT RNFLT and BMO measurements using the APS.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.