Ocular surface evaluation

Slit-lamp examination without dyes or anesthetic Observe tear meniscus height Observe quality of tear film Evaluate integrity of ocular surface Evaluate lids, lashes... 

Lopez BD, Ubels JL (1991) Quantitative evaluation of the corneal epithelial barrier effect of artificial tears and preservatives. Curr Eye Res 10(7) 645-656 Rein M (2003) The ocular surface barrier function and mechanisms of injury and repair. In Salem H, Katz S (eds) Alternative Toxicological Methods. CRC Press, New York, pp 89-108... 

Evaluate for ocular surface staining Measure TBUT... 

Tseng CL, et al. Cationic gelatin nanoparticles for dmg delivery to the ocular surface in vitro and in vivo evaluation. J Nanomater 2013 2013. 

Sensory systems Eyes The first prospective study to evaluate if benzalkonium-chloride-free travoprost 0.004% improved safety profile, particularly ocular surface tolerability, showed that the most important adverse event was conjunctival hyperaemia. It was reduced over the 3-month treatment period significantly from seven patients (23.3% at 6weeks) to only one patient (3.3%) having mild to moderate degree of hyperaemia at 12weeks [41]. 

Comeal organ culture combined with objectively quantifiable assays for comeal epithelial barrier disruption reduces the high variability associated to the subjectively scored Draize Test. The FITC-Dextran retention has been studied as a quantitative evaluation of the comeal epithelial barrier (Lopez et al. 1991) following chemical exposure of bcnzal konium chloride (BAC), Polyquad, and Thimerosal. Sodium dodecyl sulfate (SDS) has also been tested for disruption of the tight junctions via FITC-Dextran retention assay. However, as an objective outcome measure for ocular toxicity, the scoring system is not yet quantitatively comparable for assessment of ocular irritancy to multiple test products. This limitation is similar to surface biotinylation assays. As fluorometry is utilized more extensively in varied laboratories with numerous test chemicals a standardized scoring system can be elicited similar to the familiar Draize Test. 

Various lecithin-based MEs were also characterized by Hasse and Keipert [131]. The formulations were tested in terms of their physicochemical parameters (pH, refractive index, osmolality, viscosity, and surface tension) and physiological compatibility (HET-CAM and Draize test). In addition, in vitro and in vivo evaluations were performed. The tested MEs showed favorable physicochemical parameters and no ocular irritation as well as a prolonged pilocarpine release in vitro and in vivo. 

A method was described by Burton et al. (1981) involving the direct application of irritant test substance to the cornea of eyes removed immediately after sacrifice of rabbits and subsequent evaluation of the cornea for swelling, opacity, and fluorescein staining, The eye is mounted on a clamp in a temperature-controlled superfusion chamber with isotonic saline dripped onto the surface of the cornea, After an equilibrium period of 30-45 min, the test material is applied to the surface of the cornea and then washed off. Eyes are inspected macroscopically. Then, with a slit-lamp biomicroscope, the comeal thickness is measured and any fluorescein staining noted. The predictive value of the method has been confirmed in several studies (Commission of the European Communities, 1991 Koeter and Prinsen, 1985 Price and Andrews, 1985 Whittle et al., 1992), By using comeal thickness measurement, fluorescein retention, and comeal opacity as criteria for ocular injury, the suitability of the chicken eye as an enucleated model was confirmed by Prinsen and Kocier (1993) and Prinsen (1996). 

Laaksonen T, Santos H, Vihola H, Salonen J, Riikonen J, Heikkila T, Peltonen L, Kumar N, Murzin D, Lehto V, Hirvonen J (2007) Failure of MTT as a toxicity testing agent for mesoporous silicon microparticles. Chem Res Toxicol 20(12) 1913-1918 Low SP (2008) Development of porous silicon as a scaffold for the delivery of cells into ocular tissue. Flinders University, Department of Chemistry Low SP, Williams KA, Canham LT, Voelcker NH (2006) Evaluation of mammahan cell adhesion on surface modified porous silicon. Biomaterials 27 4538-4546 Masters J (2000) Animal cell culture a practical approach. OUP, Oxford... 

G.K. Jain, S.A. Pathan, S. Akhter, N. Jayabalan, S. Talegaonkar, R.K. Khar, F.J. Ahmad. Microscopic and spectroscopic evaluation of novel PLGA-chitosan Nanoplexes as an ocular delivery system. Colloids and Surfaces B Biointerfaces 82,397-403,2011. 

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