PURPOSE To assess the repeatability and reliability of IOLMaster (Carl Zeiss Meditec, Inc., Dublin, CA) axial length and keratometry measurements (K readings) with a soft contact lens on normal eyes. The method is designed for eyes with corneal irregularities or after endothelial keratoplasty. METHODS Biometry was performed on 20 healthy right eyes of volunteer subjects with mean age, 27.3 +/...

Reports on aberrational characteristics of diffractive lens usually assume the lens to be thin, with zero substrate thickness placed in air. Under these assumptions, the curvature and distortion becomes zero for both plane and curved diffractive lenses, with astigmatism given by H2K, where H is the paraxial invariant and K the lens power. However in real diffractive lenses on finite substrates,...

We present a comprehensive approach for the design of adjustable-focus lenses based on the Alvarez principle. The design methodology consists of dividing the lens into two parts: the inner, optical part, where the optical quality is optimized, and the outer, mechanical part, connecting the optical part to the frame. For the optical part, we present a complete optical design methodology to minim...

Scheimpflug images were made of the unaccommodated and accommodated right eye of 102 subjects ranging in age between 16 and 65 years. In contrast with earlier Scheimpflug studies, the images were corrected for distortion due to the geometry of the Scheimpflug camera and the refraction of the cornea and the lens itself. The different nuclear and cortical layers of the human crystalline lens were...

PURPOSE To assess the corneal swelling response to two myopic correction corneal refractive therapy (CRT) lenses of varying Dk/t values, worn for a single night. Change in thickness of the total cornea, stroma, and epithelium was measured across the horizontal meridian using optical coherence tomography (OCT). METHODS In this double-masked, randomized study, twenty subjects wore a CRT design ...

We demonstrate that changes in the behaviour of the contractile ciliary muscle accompanied by augmented rigidity of the lens are the most important aspects in the loss of accommodation. With ultrabiomicroscopy (UBM), we demonstrated that the performance of the ciliary muscle is diminished and accompanied by rigidity of the lens. Both lens thickness and trabecular-ciliary process distance (TCPD)...

It is known that when hyperopic or myopic defocus is imposed on chick eyes by spectacle lenses, they rapidly compensate, becoming myopic or hyperopic respectively, by altering the depth of their vitreous chamber. Changes in two components--ocular length and choroidal thickness--underlie this rapid compensation. With monocular lens treatment, hyperopic defocus imposed by negative lenses resulted...

In this work, we present the focusing of a Damon-Eshbach wave in a Ni80Fe20 film by a shaped, discrete transition of the film thickness. We devised an algorithm to determine the required shape of a spin-wave lens. Due to the anisotropy three geometries qualify as plano-convex lenses. One lens geometry has been realized experimentally and the emitted spin-wave pattern is investigated by time-res...

Submit Manuscript | http://medcraveonline.com but Helmholtz’s hypothesis [5,6] is one of the most accepted theories that try to explain it. According to the Helmholtz ́s model, the contraction of the ciliary muscle would allow relaxation of crystalline capsule, which, by elastic contraction, would deform the lens, increasing its thickness and, therefore, the optical power. When the ciliary muscl...

in view of the rapid expansion of contact lens amongst the users, new dimensions have been added to the domain of ophthalmology: giant papillay conjunctivitis, a disease caused by different kinds of contact lens, appears weeks or months after they are used, although some patients are struck years later. the predominant symptoms are increased awareness of lenses, ocular itching, blurred vision a...