Stockton / Modesto Ectasia Expert – Dr. Ash
Serving Tracy, Manteca, Merced
Ectasia is simply translated as dilation of a cyst or a lumen. So when a garden hose develops a bulge, the wall is stretched out and the lumen of the hose is enlarged... that is a classic ectasia. There are many part of the body that can develop ectasia. In the eye the ectasia can occur either in the back of the eye (referred to as the staphyloma) or the front part of the eye.
The cornea is the classic site of ectasia. There are several different patterns to corneal ectasias. Classically, the corneal ectasias are divided into keratoconus, pellucid marginal degeneration, and keratoglobus. There are many debates whether they are different presentation of the same disease, or completely separate entities. In either case, there are differing presentations with some overlapping characteristics. They will be presented in the following pages to come.
The Visante omni is able to provide very detailed information about the anterior surface of the eye from the ATLAS corneal topographer and also the corneal thickness from the Visante Global Pachymetric data. The combined information provides a highly accurate posterior surface elevation data. That data provides a glimpse into subtle changes occurring.
One of the key issues is that the anterior corneal surface is lined by corneal epithelium. The epithelium is a dynamic tissue that is typically 6 cell layers and 50 microns thick. In certain disease states, like dry eyes, that thickness can now change. In Ectasias, the eyelid acts as "windshield wiper" that crosses over the cornea all the time and smooths out the corneal epithelium. If there is a slight bulge, that area gets "shaved" down and the epithelium adapts to becoming thinner over the area. Since the front portion adapts to new environmental changes, the anterior surface topography may not represent the changes that are ongoing.
The corneal stroma may also develop some thinning. The posterior cornea has no mechanisms to adapt to these changes and as a consequence will bulge forward. The capacity to topographically map the posterior cornea is essential to early detection of ectasia. Visante omni provides that tool and allows for excellent detection of early ectatic corneas and determining acceptable candidacy for LASIK eye surgery.