Human corneas

Bone, R. A. and G. Draper (2007). Optical anisotropy of the human cornea determined with a polarizing microscope. Allied Optics 46 8351-8357. 

Keywords Transcorneal drug absorption Corneal epithelium Corneal cell lines Primary culture of rabbit corneal epithelium Cornea equivalents Human cornea construct... 

Figure 12.1 Schematic cross section of a human cornea (adapted, with permission from the publisher, from Kanski and Spitznas (1987) Lehrbuch der klinischen Ophthalmologie, Thieme-Verlag, Stuttgart, New York).

As can be seen above, it has been shown that cultivation of 3-D in vitro models of animal and human cornea is possible and the model resembles the in vivo cornea of the animal and human. In order to use these cornea constructs as models for in vitro drug absorption studies and alternative to the Draize test, further... 

Beuerman RW, Pedroza L. Ultrastructure of the human cornea. Microsc Res Tech 33 320-335 (1996). 

Griffith M, Hakim M, Shimmura S, Watsky MA, Li F, Carlsson D, Doillon CJ, Nakamura M, Suuronen E, Shinozaki N, Nakata K, Sheardown H. Artificial human corneas Scaffolds for transplantation and host regeneration. Cornea 21 S54-S61 (2002). 

Reichl S, Dohring S, Bednarz J, Miiller-Goymann CC. Human cornea construct HCC-an alternative for in vitro permeation studies A comparison with human donor corneas. Eur J Pharm Biopharm 60 305-308 (2005). 

The osmolarity of a healthy human cornea should be 300 mosmol/L. Studied on 100 healthy pig corneas more recent measurements give an osmolarity of 329 61 mosmol/L [6]. 

Van Trappen, L., Geboes, K., Missotten, L. Lymphocytes and Langerhans cells in the normal human cornea. Invest Ophthalmol Vis Sci 26, 220-225 (1985)... 

Becker, J., Salla, S., Dohmen, U., Redbrake, C., Reim, M. Explorative study of interleukin levels in the human cornea. Graefes Arch Clin Exp Ophthalmol 233(12), 766-771 (1995)... 

Stoiber, J., Muss, W.H., Pohla-Gubo, G., Ruckhofer, J., Grabner, G. Histopathology of human corneas after amniotic membrane and limbal stem cell transplantation for severe chemical burn. Cornea 21, 482-489 (2002)... 

Soni PS. Effects of oral contraceptive steroids on the thickness of human cornea. Am J Optom Physiol Opt 1980 57(ll) 825-34. 

S100A12 is associated with several pathological states including psoriasis (together with S100A7), inflammation, Mooren s ulcer, an autoimmune disease of the human cornea, and Kawasaki s disease, an acute multisystem vasculitits, occurring in children usually under 5 years of age (Table 2). 

Kamai, Y., and Ushiki, T. The three-dimensional organization of collagen fibrils in the human cornea and sclera. Invest. Ophthalmol. Vis. Sci. 32 2244—2258, 1991. 

CRITICAL ASSESSMENT OF THE METHOD Porcine cornea are similar to human cornea in that both have 5-7 layers of epithelial cells and a Bowman s membrane. Bovine cornea differs in that it has 10 layers of epithelial cells and no Bowman s membrane. Porcine and Bovine comeal cultures both differ in certain aspects from in vivo animal cornea. The latter has the presence of an overlying mucin layer... 

Zollman, T.M., Bragg, R.M., Harrison, D.A. (2000). Clinical effects of oleoresin capsicum (pepper spray) on the human cornea and conjunctiva. Ophthalmology 107 2186-9. 

Boljka M, Kolar G,VidensekJ. Toxic side effects of local anaesthetics on the human cornea. Br J Ophthalmol 1994 78 386-389. 

Benzalkonium chloride is used in eye-drops in concentrations of 0.033 or 0.025%. At a dilution of 1 1000 (0.1%), a drop applied to the human cornea causes mild discomfort that persists for 2 or 3 hours. Slit-lamp examination within 90 seconds shows fine grey clots (epithehal keratitis) in the corneal epithelium. Within 10 minutes, a grey haze can be seen on the comeal surface superficial desquamation of the conjunctival epithehum can follow. The superficial irritation and disturbances disappear in a day or less. 

Gasset AR. Benzalkonium chloride toxicity to the human cornea. Am J Ophthalmol 1977 84 169-171. 

Additional in vitro models and assays for eye irritation testing have been proposed in the past. An example is the porcine-based corneal opacity and permeability (PCOP) assay to predict eye irritation of water-soluble cosmetic ingredients [99]. Porcine corneas were chosen due to their advantages in comparison to the bovine corneas such as no concerns about encephalopathy diseases, regular supply of eyes with an acceptable level of quality from a slaughterhouse, more closely related to the human cornea, and their use in ophthalmic research. Using a modified holder and adapted experimental procedures 50 cosmetic ingredients were tested and compared to the in vivo Draize MAS scores. Based on their results, the study concluded that the PCOP could better predict the irritation classes than the BCOP assay. 

Van Goethem F, Adriaens E, Alepee N, Straube F, De Wever B, Cappadoro M, Catoire S, Hansen E, Wolf A, Vanparys P (2006) Prevalidation of a new in vitro reconstituted human cornea model to assess the eye irritating potential of chemicals. Toxicol In Vitro 20 1-17... 

De TK, Bergey EJ, Chung JS, et al. Polycarboxylic acid nanoparticles for ophthalmic drug delivery an ex vivo evaluation with human cornea. J Microencapsul 2004 21 841-855. 

Edelhauser HF, Maren TH. Permeability of human cornea and sclera to sulfonamide carbonic anhydrase inhibitors. Arch Ophthalmol 1988 106 1110-1115. 

Most of the damage to the eye caused by direct irradiation from the sun or artificial sources is from ultraviolet radiation. However, in the presence of a light-activated (photosensitized) diagnostic dye or drug, patients are in danger of enhanced ocular injury from ultraviolet and visible light. The extent to which a particular photosensitizer will affect the human cornea, lens, and/or retina in vivo depends upon ... 

Tlie achievement of growing human corneas in the laboratoiy will impact the transplantation of damaged or impaired corneas, the studies of corneal wound healing and eye diseases, as well as the testing of household products for toxicity. 

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