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Keratoconus

Modesto / Stockton Keratoconus Specialist – Dr. Ash
Serving Manteca, Merced, Tracy

Keratoconus is a disease of the cornea that presents as thinning of the corneal wall and its bulging forward. This bulging forward changes the shape of the cornea from a sphere to a cone like object, henceforth the name Kerato-Conus. There are several stages of this disease.

In the mildest form also referred to as the forme fruste keratoconus. This form has had a significant attention in the past decade because of LASIK eye surgery. Patients with this mild form of corneal irregularity typically have a mild prescription with some astigmatism. They may have very stable prescription. LASIK eye surgery can potentially weaken the cornea and either cause or hasten the progressive corneal bulging. Given that the earliest signs of corneal bulging forward is noted on the inside aspect of the cornea, the standard corneal topography which measures the front surface only, may miss this disease. The Visante omni allows for evaluation of the posterior surface and can help with more comprehensive pre-LASIK evaluation.

In the moderate form, the patients have a fairly high amount of nearsightedness as well as high amounts of astigmatism, yet they are able to function with glasses and contact lenses.

In the severe form, the patients are unable to have good vision with either glasses or contact lenses. In a lesser aggressive form one may be able to place Intacs to reshape the corneal and allow the use of glasses or contacts, but in the more advanced form, a corneal transplant surgery may be the only option.

 

 

The classic presentation of keratoconus involves the forward bulging of the cornea. The inner lining of the cornea called the endothelium and the thicker sublayer to it called the Descemet's membrane, get stretched out. This stretching can cause "stretch marks" referred to as the Vogt's Striae. The clinical image of which is presented to the right. Vogt Striae in Keratoconus
This forward bulging can also be seen from a side view. Rather than a perfect spherical shape, the cornea appears more as a conical object. This distortion of the cornea causes the blurring of the image. This patient eventually underwent a corneal transplant surgery.

Corneal Bulging forward in Keratoconus

 The Visante Anterior segment OCT can provide direct observation of the corneal tissue an its thinning.  Visante OCT of Keratoconus showing bulging forward and thinning centrally
  

 

When the cornea thinning as beyond what the Descemets' membrane can stretch to, a break occurs. This new break allows for the fluid in the front portion of the eye "the anterior chamber" to leak into the cornea uncontrolled. This caused to the cornea to swell and loose clarity. This event or condition is called the "corneal hydrops." The image on the right represents a clinical image seen in one of my patients.

Corneal Hydropse in Keratoconus

 

The Visante OCT image of the hydrops below clearly shows the breach in the Descemets' membrane with the fluid accumulation in the corneal tissue.

 Visante OCT of a corneal hydropse in Keratoconus

The Hydrops may resolve over a course of several months. But in some cases it may not. In the case of this patient, after 9 months the hydrops did not clear, and patient developed hydrops in the other eye as well. At that point patient was visually disabled and had to undergo a corneal transplant surgery to recover visual function.

 

Page last edited on 07/04/11


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