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We used optical coherence tomography (OCT) for non-invasive imaging of the anterior segment of the eye for
investigating partial-thickness scleral channels created with a femtosecond laser. Glaucoma is associated with elevated
intraocular pressure (IOP) due to reduced outflow facility in the eye. A partial-thickness aqueous humor (AH) drainage
channel in the sclera was created with 1.7-&mgr;m wavelength femtosecond laser pulses to reduce IOP by increasing the
outflow facility, as a solution to retard the progression of glaucoma. It is hypothesized that the precise dimensions and
predetermined location of the channel would provide a controlled increase of the outflow rate resulting in IOP reduction.
Therefore, it is significant to create the channel at the exact location with predefined dimensions. The aim of this
research has two aspects. First, as the drainage channel is subsurface, it is a challenging task to determine its precise
location, shape and dimensions, and it becomes very important to investigate the channel attributes after the laser
treatment without disturbing the internal anterior structures. Second, to provide a non-invasive, image-based verification
that extremely accurate and non-scarring AH drainage channel can be created with femtosecond laser. Partial-thickness
scleral channels created in five human cadaver eyes were investigated non-invasively with a 1310-nm time-domain OCT
imaging system. Three-dimensional (3D) OCT image stacks of the triangular cornea-sclera junction, also known as
anterior chamber angle, were acquired for image-based analysis and visualization. The volumetric cutting-plane
approach allowed reconstruction of images at any cross-sectional position in the entire 3D volume of tissue, making it a
valuable tool for exploring and evaluating the location, shape and dimension of the channel from all directions. As a
two-dimensional image-based methodology, an image-processing pipeline was implemented to enhance the channel
features to augment the analysis. In conclusion, we successfully demonstrate that our image-based visualization tool is
appropriate for effective investigation and evaluation of femtosecond laser-created, partial-thickness aqueous humor
drainage channels in the sclera.
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