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Tear Film Stability (tear + film_stability)
Selected AbstractsNumerical analysis of interferograms for evaluation of tear film build-up timeOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 3 2009Dorota H. Szczesna Abstract The lateral shearing interferometer was applied to the in vivo dynamic investigation of the external surface of the pre-corneal tear film after an eye blink. Sequences of interferograms were recorded at a sampling frequency of 25 Hz. Immediately after every eye blink, a bright pattern was observed under the interference fringes. This disappeared after a short time interval (around 0.5,2 s): smooth interference fringes were then observed, corresponding to the creation of a smooth anterior optical surface over the cornea. The purpose of this study is to describe in detail the kinetics of pre-corneal tear film stability and to propose quantitative measures of the stabilisation process in healthy eyes during the 3 s period after a blink. Two methods of quantitative assessment of the tear film build-up time are presented. The first is based upon the evaluation of the inhomogeneity of the background of the interferogram; the second evaluates the orientation of the structure of the background by the analysis of the zero order of the Fast Fourier Transform (FFT) spectrum. The quasi-vertically oriented bright line patterns observed in interferograms immediately after a blink and the mirror-symmetry of their tilts for right and left eyes indicate that the pattern is related to the wiping movements of the upper eyelids during the eye blink. [source] 3445: Evaluation, diagnosis and grading of severity of MGDACTA OPHTHALMOLOGICA, Issue 2010AJ BRON Purpose To evaluate current diagnostic tests and make future recommendations. Methods An evidence-based review of procedures. Results MGD is a common symptomatic disorder leading to associated ocular surface disease including evaporative dry eye. A two stage diagnostic approach is recommended including an assessment of meibomian function based on lid morphology, gland mass, expressibility, lipid layer appearance and tear evaporation. A diagnosis of dry eye is based on measures of tear production and clearance, tear osmolarity, tear film stability and the presence of ocular surface changes revealed by tissue staining and inflammatory biomarkers. Quantification of MGD depends on grading meibum quality and expressibility. Newer, quantitative methods will make grading more accurate in the future and include quantitative meibomian expression, non-invasive meibography, confocal microscopy, video-interferometry and the use of inflammatory biomarkers. Meibomian gland dropout can be to monitor and stratify MGD in clinical trials. Conclusion A provisional severity rating of MGD and MGD-related disease has been proposed as a guide to the selection of treatment and the monitoring of disease progression. [source] 3224: Chitosan in the treatment of dry eyeACTA OPHTHALMOLOGICA, Issue 2010L SCHMETTERER Purpose To demonstrate the safety and efficacy of a new eye drop formulation containing a novel thiolated biopolymer, namely chitosan-N-acetylcysteine, in a number of pre-clinical tests. It is postulated that interaction between thiol groups of the topically applied chitosan-N-acetylcysteine and cysteine-rich mucin (MUC5AC) increases polymer residence time on the ocular surface and tear film stability. Methods The efficacy of isotonic and buffered chitosan-N-acetylcysteine eye drops was evaluated in two different dry eye mouse models. The dosage dependent ocular residence time and biodistribution were investigated in a rabbit model using microPET technology. Long-term irritation and delayed-type hypersensitivity tests with chitosan-N-acteylcysteine eye drop formulation were conducted in rabbits. Results In both dry eye studies mice treated with chitosan-N-acetylcysteine showed decreased expression of ocular surface mRNA of IL-,, IL-10, IL-12,, and TNF, indicating that the formulation may have protective ocular surface properties. The residence time of chitosan-N-acetylcysteine eye drops on the ocular surface of rabbits was increased (detection up to 22h). Results of a long-term ocular irritation study in rabbits demonstrate that the novel formulation is well tolerated and non-irritant to the eye. Conclusion Based on the promising pre-clinical study results both in terms of efficacy and safety a clinical phase 1 trial is scheduled in the near future. Commercial interest [source] Tear functions in patients with pingueculaACTA OPHTHALMOLOGICA, Issue 3 2001Halit Oguz ABSTRACT. Purpose: To investigate the tear flow, tear film stability and condition of mucus in patients with pinguecula. Methods: The Schirmer I and ferning tests were performed and break-up time (BUT) was determined in 57 patients with pinguecula [random eyes; 34 males and 23 females, 18 to 70 years of age (mean±SD: 39.1±13.5 years)] and in 57 age-matched subjects (control) [random eyes; 35 males and 22 females, 11 to 70 years of age (mean±SD: 37.8±15.2 years)], and the test results were statistically analysed. Results: The mean Schirmer test value was 22.72±12 mm in the eyes with pinguecula and 22.7±8.5 mm in the control eyes. There was no statistically significant difference (t=0.01, p=0.99) between the groups. The mean BUTs were 11.42±6.89 s in the eyes with pinguecula and 15.46±5.85 s in the control eyes. Comparison of BUTs between the groups revealed a statistically significant difference (t=3.37, p=0.0010). Also, ferning types were found to be significantly abnormal in the eyes with pinguecula (p<0.01). Conclusion: The alteration in the mucin layer is a possible change inducing pinguecula formation, or it may reflect an already existing pathology in the cells on the ocular surface. [source] | ||||||||||