Eyeworld Daily News

8 Friday, April 17, 2015 EW SHOW DAILY by Chiles Aedam R. Samaniego EyeWorld Asia-Pacific Senior Staff Writer T he first accurate description of keratoconus is wide- ly believed to have been written in 1854 by John Nottingham; however, Nottingham's 270-page treatise on the subject is not widely read. These facts prompted Akilesh Gokul, PhD, Auckland, and co-author Charles McGhee, MD, PhD, Auckland, to review Nottingham's description and compare it to our current understanding of the condition. Dr. Gokul presented their paper, "A 160-Year Pursuit: Recount and Comparison of Nottingham's Trea- tise on Conical Cornea to Current Knowledge on Keratoconus," at a free paper session at World Cornea Congress (WCC) VII on Thursday morning. Drs. Gokul and McGhee re- viewed literature on keratoconus from 1984 to 2014. Epidemiologically, Nottingham estimated the prevalence of "con- ical corneas" to be 100 to 300 per 100,000; he also observed an ethnic predilection. Current estimates put the prevalence at 86,000 to 23,000 per 100,000, while current evidence does support an "ethnic predisposition," with, for instance, significantly high- er prevalence of keratoconus in Israel and Denmark. Nottingham described non- inflammatory and inflammatory factors in the etiology and alluded to the role of genetics and the environ- ment; today, the etiology is hypothe- sized to be "2-hit"—with genetic pre- disposition and some environmental insult resulting in the condition. In terms of pathogenesis, Nottingham described an attenua- tion in innervation and disruption of corneal "nutrition"; today a perturbation of sub-basal nerve distribution has been observed. Using just the naked eye and a magnifying lens, Nottingham observed the key characteristics of the clinical presentation we know today: increase in curvature with a corneal steepening; thinner corneas; an increase in anterior chamber depth; an occasional loss of transpar- ency. These characteristics are now better observed with a slit lamp, and topography and tomography allow diagnosis at a much earlier stage, measuring these same characteristics. easy, she said; what is difficult is distinguishing keratoconus from eyes with high ammetropia. The authors concluded that "[a] symmetry values between eyes in asphericity, curvature and elevation parameters" were effective in dis- criminating between the 2 condi- tions. EW Editors' note: The speakers have no financial interests related to the content of their talks. Nottingham also described the "conical cornea" as "weakened and thinned," which is now quantified as the result of biomechanical com- promise. Dr. Gokul concluded that while much of what Nottingham reported was "likely limited by technology and shortcomings in the under- standing of anatomy and physi- ology," his observations and ideas are "exceptionally accurate"—even considering all the investigation that has taken place in the intervening 160 years since the publication of Nottingham's treatise. In fact, the diagnosis of kera- toconus remains problematic, and different experts propose different parameters to measure for diagnosis. For instance, Maria A. Henriquez, MD, Lima, Peru, observed that "our bodies are sym- metrical, our eyes are symmetrical, too." However, in keratoconic eyes, there is a high degree of asymmetry. And yet, Dr. Henriquez observed further, ophthalmologists tend to evaluate the condition unilaterally. Dr. Henriquez, together with co-authors Luis Izquierdo Jr., MD, Lima, Peru, Jaqueline Parraga, MD, Lima, Peru, and Michael W. Belin, MD, Tucson, Ariz., examined "Intereye Asymmetry in Eyes with Forme Fruste Keratoconus, Kera- toconus, and High Astigmatism and Myopia: Scheimpflug Imaging Analysis." As the title of their free paper states, Dr. Henriquez and her col- leagues used Scheimpflug imaging to analyze more than 30 parameters, with particular focus on intereye asymmetry. Distinguishing between normal eyes and eyes with keratoconus is Keratoconus, over 160 years of investigation Dr. Gokul discusses Nottingham's 1854 treatise on keratoconus, saying it remains "exceptionally accurate."

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