Several studies have shown that growth of the primate eye responds in a compensatory direction to both positive and negative spectacle lenses--eyes grow more slowly and become hyperopic in response to positive lenses, and eyes grow more rapidly and become myopic in response to negative lenses. On the other hand, extended wear soft contact lenses, whether positively or negatively powered, induce...

PURPOSE A four-month extended wear clinical trial was conducted to compare the ocular effects of a high Dk Balafilcon A silicone hydrogel lens and a low Dk HEMA 38.6 per cent H20 soft lens. METHOD Twenty-four subjects who were adapted to daily wear of soft lenses wore a high Dk lens in one eye and a low Dk HEMA lens in the other eye for four months on an extended wear basis after one week of ...

PURPOSE Soft contact lenses have been reported to increase the progression of myopia. The purpose of this study was to determine whether soft contact lenses affect the progression of myopia in children. METHODS Children between the ages of 8 and 11 years with -1.00 to -6.00 D myopia and less than 1.00 D astigmatism were randomly assigned to wear soft contact lenses (n = 247) or spectacles (n ...

One of the commonest causes of soft lens spoilation is the formation of opacities within the matrix and/or on the surface of the lens. These opacities may develop after varying periods of wear and, at times, after as short as 48 hrs of continuous use. In addition to impairing the optical property of the lens, the opacities can be a cause of lens intolerance. Although aetiological factors, such ...

PURPOSE Pseudomonas aeruginosa is the most important cause of contact lens-associated ulcerative keratitis, especially for those who use extended-wear lenses. Until now, the presence of specific anti-P. aeruginosa immunoglobulin A (IgA) antibodies in the tears of contact lens wearers has not been investigated and is the purpose of the current study. METHODS The levels of specific IgA antibodi...

purpose: to evaluate the prevalence of contat lens wear among highschool girls and their general knowledge about contact lenses and also to evaluate the specific knowledge of contact lens wearers about the lens. methods: in a cross-sectional study, 1664 students of 22 randomly selected girl highschools were enrolled. a questionaire including questions about wearing contact lens, age of first us...

A review of 100 patients who underwent penetrating keratoplasty revealed 47 who required therapeutic soft contact lenses in the early postoperative period. Twelve corneal ulcer-infiltrates, 11 of which were culture positive, occurred during soft contact lens wear (23% incidence of this complication in contact lens fitted eyes). The most common offending organism was coagulase-negative staphyloc...

Lens system design is an important factor in image quality. The main aspect of the lens system design methodology is the optimization procedure. Since optimization is a complex, non-linear task, soft computing optimization algorithms can be used. There are many tools that can be employed to measure optical performance, but the spot diagram is the most useful. The spot diagram gives an indicatio...

Iris is one of the most promising biometric modalities, and is in usual use in enormously large-scale applications. The presences of a contact lens, mainly a textured cosmetic lens, create a challenge to iris recognition as it obfuscates the natural iris patterns. Earlier work used novel lens detection algorithm with Modified Local Binary Pattern analysis (MLBP) features to produce feature valu...

PURPOSE Because presbyopia is thought to be accompanied by increased lens sclerosis this study was conducted to investigate whether refilling the capsule of the presbyopic human lens with a soft polymer would restore the ability of the lens to undergo accommodative changes. METHODS Accommodative forces were applied to natural and refilled lenses by circumferential stretching through the cilia...