Journal of Refractive Surgery

New Technology 

Corneal Epithelial Thickness Profile in the Diagnosis of Keratoconus

Dan Z. Reinstein, MD, MA(Cantab), FRCSC, FRCOphth; Timothy J. Archer, MA(Oxon), DipCompSci(Cantab); Marine Gobbe, MST(Optom), PhD

Abstract

PURPOSE

To illustrate the hypothesis that epithelial thickness profile maps could be used as an adjunctive tool to improve the sensitivity and specificity of keratoconus screening by presenting a case series of examples.

METHODS

The Artemis very high-frequency digital ultrasound arc-scanner was used to obtain epithelial thickness profiles in addition to a comprehensive ophthalmic examination to screen for keratoconus. Five case examples are presented; a normal eye, an eye with advanced keratoconus, and three cases where a diagnosis of keratoconus was uncertain based only on the ophthalmic examination.

RESULTS

The epithelial thickness profile in the normal eye was slightly thinner superiorly, consistent with that previously described for a normal population. The keratoconic eye demonstrated an epithelial doughnut pattern of epithelial thinning over the cone surrounded by an annulus of epithelial thickening. In case 1, an epithelial doughnut pattern confirmed the presence of keratoconus in an eye with an abnormal front surface topography. In case 2, the absence of an epithelial doughnut pattern excluded a diagnosis of keratoconus in a patient with an abnormal front surface topography. In case 3, the presence of an epithelial doughnut pattern coincident with an eccentric posterior elevation best-fit sphere indicated a diagnosis of keratoconus. The epithelium appeared to have compensated for the stromal surface cone, resulting in an apparently normal front surface topography.

CONCLUSIONS

An epithelial doughnut pattern appears to indicate the presence of an underlying stromal cone; the lack of an epithelial doughnut pattern would indicate that an abnormal topography was not due to keratoconus. In very early keratoconus, epithelial compensation can mask the presence of an underlying cone on front surface topography, ie, a diagnosis of keratoconus might be missed. [J Refract Surg. 2009;25:604-610.]

doi:10.3928/1081597X-20090610-06

AUTHORS

From London Vision Clinic, London, United Kingdom (Reinstein, Archer, Gobbe); the Department of Ophthalmology, St Thomas’ Hospital - Kings College, London, United Kingdom (Reinstein); the Department of Ophthalmology, Weill Medical College of Cornell University, New York, NY (Reinstein); and Centre Hospitalier National d’Ophtalmologie, Paris, France (Reinstein).

Dr Reinstein has a proprietary interest in the Artemis technology (ArcScan Inc, Morrison, Colo) and is the author of patents administered by the Cornell Research Foundation, Ithaca, NY. The remaining authors have no proprietary or financial interest in the materials presented herein.

Correspondence: Dan Z. Reinstein, MD, MA(Cantab), FRCSC, FRCOphth, London Vision Clinic, 8 Devonshire Pl, London W1G 6HP, United Kingdom. Tel: 44 207 224 1005; Fax: 44 207 224 1055; E-mail: dzr@londonvisionclinic.com

Received: October 9, 2008; Accepted: May 6, 2009

Abstract

PURPOSE

To illustrate the hypothesis that epithelial thickness profile maps could be used as an adjunctive tool to improve the sensitivity and specificity of keratoconus screening by presenting a case series of examples.

METHODS

The Artemis very high-frequency digital ultrasound arc-scanner was used to obtain epithelial thickness profiles in addition to a comprehensive ophthalmic examination to screen for keratoconus. Five case examples are presented; a normal eye, an eye with advanced keratoconus, and three cases where a diagnosis of keratoconus was uncertain based only on the ophthalmic examination.

RESULTS

The epithelial thickness profile in the normal eye was slightly thinner superiorly, consistent with that previously described for a normal population. The keratoconic eye demonstrated an epithelial doughnut pattern of epithelial thinning over the cone surrounded by an annulus of epithelial thickening. In case 1, an epithelial doughnut pattern confirmed the presence of keratoconus in an eye with an abnormal front surface topography. In case 2, the absence of an epithelial doughnut pattern excluded a diagnosis of keratoconus in a patient with an abnormal front surface topography. In case 3, the presence of an epithelial doughnut pattern coincident with an eccentric posterior elevation best-fit sphere indicated a diagnosis of keratoconus. The epithelium appeared to have compensated for the stromal surface cone, resulting in an apparently normal front surface topography.

CONCLUSIONS

An epithelial doughnut pattern appears to indicate the presence of an underlying stromal cone; the lack of an epithelial doughnut pattern would indicate that an abnormal topography was not due to keratoconus. In very early keratoconus, epithelial compensation can mask the presence of an underlying cone on front surface topography, ie, a diagnosis of keratoconus might be missed. [J Refract Surg. 2009;25:604-610.]

doi:10.3928/1081597X-20090610-06

AUTHORS

From London Vision Clinic, London, United Kingdom (Reinstein, Archer, Gobbe); the Department of Ophthalmology, St Thomas’ Hospital - Kings College, London, United Kingdom (Reinstein); the Department of Ophthalmology, Weill Medical College of Cornell University, New York, NY (Reinstein); and Centre Hospitalier National d’Ophtalmologie, Paris, France (Reinstein).

Dr Reinstein has a proprietary interest in the Artemis technology (ArcScan Inc, Morrison, Colo) and is the author of patents administered by the Cornell Research Foundation, Ithaca, NY. The remaining authors have no proprietary or financial interest in the materials presented herein.

Correspondence: Dan Z. Reinstein, MD, MA(Cantab), FRCSC, FRCOphth, London Vision Clinic, 8 Devonshire Pl, London W1G 6HP, United Kingdom. Tel: 44 207 224 1005; Fax: 44 207 224 1055; E-mail: dzr@londonvisionclinic.com

Received: October 9, 2008; Accepted: May 6, 2009

10.3928/1081597X-20090610-06

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