The impact of artificial light scatter on scanning laser tomography
Mark A Burke1, Chaten J Khanna, Angela Miller
1School of Optometry, University of Waterloo, Waterloo, Ontario, Canada.
Purpose:
The impact of cataract (which frequently occurs alongside glaucoma) on scanning laser tomography (SLT) is poorly understood. The aim of this pilot study was to determine the impact of artificial light scatter on SLT estimates of optic nerve head (ONH) topography.
Methods:
The sample comprised 10 healthy, young subjects of mean age 23.5 years. One eye of each subject was randomly selected. Cells filled with increasing concentrations of 0.50-microm diameter polystyrene microspheres were prepared. The cells were mounted in front of the objective lens of the Heidelberg Retina Tomograph (HRT) II and were tilted at an angle of 20 degrees to eradicate any surface reflections. Three sets of ONH scans were initially acquired without any light scatter cell in place and then three further sets were acquired for each of four different concentrations of microspheres in a randomized order. The impact of artificial light scatter on cup-to-disc area ratio, cup volume, rim volume, cup shape measure, height variation contour, and mean retinal nerve fiber layer (RNFL) thickness was evaluated.
Results:
Repeated-measures analysis of variance showed that there was no significant change in cup-to-disc area ratio, cup volume, rim volume, height variation contour, cup shape measure, or mean RNFL thickness as a function of increasing light scatter cell concentration.
Conclusion:
Artificial light scatter had no statistically significant impact on the stereometric parameters of the HRT II. From a clinical perspective, useful SLT data can be acquired with confidence from patients with diagnosed/suspected glaucoma and concomitant cataract.
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