No description available.

Purpose: To grade cataract changes in a Guatemala population with direct ophthalmoscopy and a grading system based on the grading system used by V. Mehra and D. C. Minassian in 1988. Methods: A population from Guatemala who attended field clinics conducted by Vision For All were included in this study. The sample consisted of 352 participants, 219 women and 133 men, from 9-90 years old. Mean age of the participants was 47.9 ± 17.8 years old. Binocular VA and subjective refraction was obtained with trial lenses and a Snellen E-chart at 5 meters. A 2 mm pinhole was used monocularly with the subjective refraction and whether participants felt any improvement in VA was documented.  The opacities in the red reflex in the crystalline lens were graded using a handheld direct ophthalmoscope. The grading was made in an angle of 25o nasal and at approximately 33 cm from the participant’s undilated eye. Results: The prevalence of cataract was 28.6% and 68% had some form of opacity in the red reflex. There was no statistically significant difference (p > 0.05) between the grade of lens opacities in right and left eye. Mean grade of lens opacities in right eye was 1.64 ± 1.46 and 1.63 ± 1.43 in left eye. The analysis showed a highly significant correlation between age and grade of lens opacities in right eye (y = 0.0657x -1.5106; r = 0.8; p < 0.001) and left eye (r = 0.78; p < 0.001). Lens opacities start to develop at an average age of 38.5 years in this population. There was a significant correlation between aided VA and grade of lens opacities for right eye (r = 0.52; p < 0.05) and left eye (r = 0.49; p < 0.05). 72 participants (20.5%) who had grading 3-5 in one or both eyes felt an improvement in their vision with the pinhole. Conclusions: The prevalence of cataract was 28.6% and this population had an earlier development of cataract compared to previous studies. This could be due to the UV-radiation, the temperature and nutrition and antioxidant insufficiency. Also this study showed a highly significant correlation between age and grade of lens opacities and a low, but significant, correlation between aided VA and grade of lens opacities.

Changes in the mechanics of the lens capsule of the eye arising from alterations of its native configuration can lead to undesirable clinical results. One example is the surgical introduction of a hole into the lens capsule and subsequent removal of the cloudy lens during cataract surgery. The adverse effect is secondary cataract on the posterior lens capsule, brought about by a sudden proliferation of lens epithelial cells in the region. Understanding the biomechanics of the anterior lens capsule is necessary in order to model its behavior under various physiological conditions and predict its response to alterations and perturbations such as those during cataract surgery. Such knowledge will help in the improvement of techniques during cataract surgery, and in the design of artificial intraocular lens. In this study we present, for the first time, results that demonstrate that the anterior lens capsule exhibits non-homogeneity and regionally varying anisotropy. We also compute stresses in the lens capsule due to normal loading conditions and procedures such as a capsulorhexis.

Thesis (Ph. D.)--University of Missouri--Columbia, 2001. / "December 2001." Typescript. Vita. Includes bibliographical references (leaves 153-159). Also available on the Internet.

Cataract has been defined by Bourne as any pathological condition of the lens which alters its normal transparency. More specifically, a cataract is regarded as a loss of transparency of the lens, or an opacification occurring at any place in the lens or its capsule. Since the lens is an intricate physico-chemical system, changes in the physical and chemical state of the lens proteins which result in loss or transparency or opacification may be brought about by many agents: interference with the normal metabolic processes, alteration in hydrogen ion concentration, disturbance of osmotic equilibrium, and the harmful action of heat, light, and radiation. As a result, cataract presents many complexities with respect to clinical manifestations. [...]

No description available.

There have been several reports that cataract development results from unregulated Ca2+ mediated degradation of lens crystallins. The calpain isoform m-calpain, a cysteine protease, is known to be a major player in cataract formation in rodent lenses and recent evidence indicates that over-activation by Ca2+ causes cataractogenesis in other mammals. Molecular modelling studies of seventeen analogues of compound SJA6017 (our lead compound) in a calpain model are compared to measured IC50 values against ovine calpain. The studies validated the potential of the ‘model’, method and defined activity criteria that could be used as a tool to select molecules to synthesize as potential calpain inhibitors. Using this screening methodology and two virtual libraries of potential inhibitory molecules led to the synthesis of several inhibitors including macrocyclic 811. In vitro sheep eye lens culture experiments showed that macrocycle 811 possessed the characteristics to slow cataractogenesis.

This thesis summarises the progress made in the design and synthesis of conformationally constrained β-strand peptidomimetic compounds using ring closing metathesis methodology under microwave irridation conditions. The best macrocycle were elaborated into an inhibitor for a specific protease target. Calpain was used as an example of protease targeting cataract disease. Chapter One introduces proteases in general centring on the general context of protease inhibitor design. The significant of the β-strand 'bioactive' conformation is discussed in details in particular the exploitation of conformationally constrained to potential lock the 'bioactive' conformation. Chapter Two illustrates in silico methods used to design a series of β-strand macrocycle 2.1-2.7. The analysis of these is performed using molecular modelling software Schrodinger suite (2005). A brief discussion of ring closing metathesis methodology is also included. Chapter Three describes the synthesis of the precursor required for RCM reactions (tripeptides dienes). Various types of allylated amino acid side chains were synthesised. The tripeptides were obtained using standard peptide coupling methodology utilising reagents such as HATU, EDC and HOAT. Chapter Four describes the application of ring closing metathesis for the synthesis of β-strand macrocycles. The development of a new reaction conditions to optimise the ring closing metathesis reaction is discussed. In particular the effect of the use of a Lewis acid (chlorodicyclohexylborane) additive in RCM reactions is investigated. Chapter Five discusses the mechanism of cataract formation, cataract treatment and the potential development of calpain inhibitors. One of the macrocycles synthesised in chapter 4 is elaborated into a calpain inhibitor. The in-vitro assay result of this is presented and this compound is currently undergoing in vivo evaluation.

Thesis (M. Med. Sc.)--University of Hong Kong, 2007.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2001. / Härtill 6 uppsatser.