Effect of optical density filters on retinal nerve fiber layer and macular inner retinal layer thickness measurements using spectral domain optical coherence tomography

Optical coherence tomography (OCT) is an objective imaging technique, based on
coherence interferometry.1 Spectral domain (SD) OCT, also known as Fourier
Domain OCT, allows fast acquisition of images with high resolution, and with
SD-OCT one can make very accurate measurements
OCT is non-invasive technique and just lightly burdensome for patients. It only
takes a few seconds to acquire the images and the whole procedure takes a few
minutes, dependant on the amount of scans required.

Retinal nerve fiber layer (RNFL) thickness measurements are one of the OCT
measurements that have shown good reproducibility and good diagnostic abilities
for the diagnosis of primary open angle glaucoma. Thickness measurement of the
macular inner retinal layer in the macular region has also shown promise as
diagnostic measurement for the detection of glaucoma.

Previous studies have demonstrated that RNFL thickness measurements are
influenced by cataract. A linear relationship has been described between
OCT-equivalent optical density of cataract and underestimation of RNFL
thickness measured with OCT.

We aim to identify and quantify the influence of artificial filters with a
predefined optical density on retinal nerve fiber layer (RNFL) measurements,
and inner retinal layers using spectral domain optical coherence tomography
(SD-OCT), as well as the effect of cataract on the filter measurements.

RNFL thickness measurements with SD-OCT can be done using different scan
protocols. Most SD-OCT instruments feature a 3D data set protocol and circular
scan protocol. We intend to evaluate the reproducibility and agreement of two
SD-OCT scan protocols for RNFL thickness layer measurements.

The purpose of this study is to identify and quantify the influence of medium
opacity on RNFL and inner retinal layer thickness measurements using SD-OCT, as
well as the effect of cataract on the filter measurements.

Also to evaluate the reproducibility and agreement of two different SD-OCT scan
protocols for RNFL thickness layer measurements

A cross sectional study involving healthy subjects, glaucoma and cataract
patients

Participants of this study will not be exposed to invasive methods. The study
will require time of the patients. Furthermore mydriatic drops will be
instilled that can temporarily cause a slight decrease in vision. In rare cases
an allergic reaction can occur, which can temporarily cause redness of the eye.