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Deol M, Ehrlich JR, Shimmyo M et al.

New York University School of Medicine, New York, NY, USA.

 J Cataract Refract Surg 2015;41:1176–81.

Bruce James’s review: The authors of this study define corneal hysteresis as the difference in air pressure on inward and outward applanation. It is measured with a Reichert ocular response analyzer and gives an indication of how the eye responds to intraocular pressure (IOP) changes; i.e. how the cornea absorbs and dissipates energy. Low hysteresis indicates that the eye may have little capacity to absorb the energy caused by an increase in IOP and may be more at risk of developing glaucoma. It has thus been suggested as a risk factor, or surrogate risk factor, for the development of glaucoma.

However, studies have shown that eyes with lower hysteresis are also more responsive to pharmacological treatment for high IOP. This was observed in this retrospective study of 39 patients without glaucoma undergoing cataract surgery. The IOP reduction ranged from 3.2mmHg in the lowest hysteresis group to 1.3mmHg in the highest hysteresis group. The various theoretical considerations for this result, including the effect of a higher baseline IOP, are discussed. Central corneal thickness was not found to have an effect on IOP; however, this has previously been suggested to have a role in determining the degree of IOP reduction. Corneal hysteresis measurements may prove useful when refining treatment options for an individual patient.

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