Shimizu Foundation for Immunological Research Grant. Online-Only Material: The eAppendix is available at http: //www.archophthalmol.com. Additional Contributions: Chikako Endo provided tech- nical assistance. 1. Yagi T, Sotozono C, Tanaka M, et al. Cytokine storm arising on the ocular surface in a patient with Stevens-Johnson syndrome. Br J Ophthalmol. 2011; 95(7):1030-1031. 2. Ueta M, Sotozono C, Nakano M, et al. Association between prostaglandin E receptor 3 polymorphisms and Stevens-Johnson syndrome identified by means of a genome-wide association study. J Allergy Clin Immunol. 2010;126(6): 1218-1225, e10. 3. Ueta M, Matsuoka T, Yokoi N, Kinoshita S. Prostaglandin E2 suppresses poly- inosine-polycytidylic acid (polyI:C)-stimulated cytokine production via pros- taglandin E2 receptor (EP) 2 and 3 in human conjunctival epithelial cells. Br J Ophthalmol. 2011;95(6):859-863. 4. Ueta M, Matsuoka T, Yokoi N, Kinoshita S. Prostaglandin E receptor subtype EP3 downregulates TSLP expression in human conjunctival epithelium. Br J Ophthalmol. 2011;95(5):742-743. 5. Ueta M, Kinoshita S. Innate immunity of the ocular surface. Brain Res Bull. 2010;81(2-3):219-228. 6. Takayama K, Garcı´a-Cardena G, Sukhova GK, Comander J, Gimbrone MA Jr, Libby P. Prostaglandin E2 suppresses chemokine production in human mac- rophages through the EP4 receptor. J Biol Chem. 2002;277(46):44147-44154. Depth Profile Study of Abnormal Collagen Orientation in Keratoconus Corneas I n a previous study, 1 we used femtosecond laser tech- nology to cut ex vivo human corneas into anterior, mid, and posterior sections, after which x-ray scatter patterns were obtained at fine intervals over each speci- men. Data analysis revealed the predominant orientation of collagen at each sampling site, which was assembled to show the variation in collagen orientation between cen- tral and peripheral regions of the cornea and as a function of tissue depth. We hypothesized that the predominantly orthogonal arrangement of collagen (directed toward op- posing sets of rectus muscles) in the mid and posterior stroma may help to distribute strain in the cornea by al- lowing it to withstand the pull of the extraocular muscles. It was also suggested that the more isotropic arrangement in the anterior stroma may play a role in tissue biomechan- ics by resisting intraocular pressure while at the same time maintaining corneal curvature. This article, in conjunc- tion with our findings of abnormal collagen orientation in full-thickness keratoconus corneas, 2,3 received a great deal of interest from the scientific community and prompted the following question: how does collagen orientation change as a function of tissue depth when the anterior cur- vature of the cornea is abnormal, as in keratoconus? Herein, we report findings from our investigation aimed at answer- ing this question. Methods. The Baron chamber used in our previous study 1 was adapted to enable corneal buttons to be clamped in place and inflated (by pumping physiological saline into the posterior compartment) to restore their natural cur- vature. A button diameter of 8 mm or larger was deemed necessary to ensure tissue stability during this process. The next step, obtaining fresh, full-thickness, kera- toconus buttons of sufficient diameter, proved to be prob- lematic owing to the increasing popularity of deep an- terior lamellar keratoplasty. Recently, however, the opportunity arose to examine an 8-mm full-thickness (300-340 μm minus epithelium) keratoconus corneal but- ton with some central scarring and a mean power greater than 51.8 diopters (Figure 1). The tissue was obtained in accordance with the tenets of the Declaration of Hel- sinki and with full informed consent from a 31-year-old patient at the time of penetrating keratoplasty. Using tech- niques detailed previously, 1 the corneal button was clamped in the chamber and inflated. The central 6.3-mm region of the button was then flattened by the applana- tion cone and a single cut was made at a depth of 150 μm from the surface using an IntraLase 60-kHz femto- second laser (Abbott Medical Optics Inc), 1 thus split- ting the cornea into anterior and posterior sections of roughly equal thickness. Wide-angle x-ray scattering pat- terns were collected at 0.25-mm intervals over each cor- Nasal Diopters 56 54 52 50 48 46 44 42 40 38 36 34 32 30 Figure 1. Corneal topography of the keratoconus cornea (recorded 12 years previously). 3 The broken lines show the 6.3-mm region of the cornea cut with the femtosecond laser (circle) and the region of greatest corneal steepening depicted in Figure 2 (rectangle). Normal A C D B F E Keratoconus ÷1.0 ÷1.8 ÷3.5 ÷5.0 Downsizing Anterior 0-150 μm Anterior 0-200 μm Posterior 150-300 μm Posterior 400-600 μm Figure 2. Collagen orientation in the normal (A) and keratoconus (B) posterior stroma (central 6.3 mm). The highlighted regions of the posterior (C and D) and anterior (E and F) stroma are expanded. Large vector plots showing high collagen alignment are downsized (key). ARCH OPHTHALMOL / VOL 130 (NO. 2), FEB 2012 WWW.ARCHOPHTHALMOL.COM 251 ©2012 American Medical Association. All rights reserved. at Cardiff University, on February 14, 2012 www.archophthalmol.com Downloaded from