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Understand the Cornea
Measuring the biomechanical properties of the cornea with the Ocular Response Analyzer enables researchers and practitioners, for the first time, to quantify various corneal conditions by means of a measurable and repeatable metric. Low Corneal Hysteresis (CH) demonstrates that the cornea is less capable of absorbing (damping) the energy of the air pulse. The differences in CH between normal and compromised corneas are highly evident, and lead some experts to theorize that normal eyes exhibiting significantly lower than average CH may be at risk of developing corneal disorders in the future. Clinical data from several studies show a universal reduction in post-LASIK CH. Some experts hypothesize that this is not primarily a function of corneal thinning, but rather a result of weakening of the structure related to creation of the flap. |
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“There is a major concern for most refractive surgeons about preventing post-LASIK ectasia. Devices that can help us learn more about the ‘signature’ of the cornea pre-operatively may alert us to patients that are at a higher risk of developing ectasia”
Jay Pepose, MD, PhD, Medical Director, Pepose Vision Institute |
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Corneal Hysteresis of 15 eyes pre- and post-LASIK
The Ocular Reponse Analyzer’s ability to characterize the biomechanical properties of the cornea means that potential refractive surgery candidates can be more effectively evaluated for potential post-surgical complications, such as corneal ectasia, than by using CCT and topography alone.
The Ocular Hypertension Treatment Study (OHTS), as well as other studies, have brought to light the importance of corneal parameters in diagnosing and managing glaucoma. These studies have shown that low CCT (thin cornea) is an independent risk factor for the development and progression of the disease. Many experts believe that corneal parameters other than CCT may provide clues that will aid in the diagnosis and management of glaucoma. There is evidence to suggest that the cornea may reflect the condition of the lamina cribrosa. Clinical studies utilizing the Ocular Response Analyzer support this hypothesis and have confirmed that low CH is an independent indicator of glaucomatous damage and progression.
It has also been demonstrated that lower-than-average CH is observed in subjects who have been identified as “Normal Tension Glaucoma” (NTG) patients. Currently, individuals who have NTG may be missed during routine IOP screening. If the CH parameter proves to be a reliable indicator of this condition, it would be a significant advance in glaucoma screening.
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