Our aim was to develop special spectacles and contact lenses capable of solving common refractive errors such as myopia, hyperopia and regular and irregular astigmatism, as well as other accommodative insufficiency states (e.g., presbyopia), by exploiting brain's capability to adapt to contrast. Normally, these refractive errors are treated with adjusting a refractive correction. The method we used was adapting a special all-optical extended depth of focus concept taken from digital imagery. Special thin phase-only binary mask containing annular-like spatially large structures was developed to provide extension of the focus depth. This creates a “funnel” in the retina plane that is insensitive to defocus. The image is shown with no reduction of the spatial spectral content but with a reduction of the imaging contrast. Due to brain adaptation, the contrast reduction is corrected and brought into the normal (standard) range. Here we present experimental bench results as well as preliminary clinical trials. The clinical testing included measuring the visual acuity under different illumination conditions (pupil size varied from 2 to 4 mm), as well as stereoscopy, color vision and contrast sensitivity. In the optical bench, the optical element showed an extension of 2.5 Diopters. In the clinical tests, we found an improvement of up to 3 Diopters in presbyopic subjects for pupil sizes of 2 to 4 mm and improvement of more than 2 Diopters for regular and irregular astigmatism. The high-level performance of the proposed element, including the high contrasted quality vision is obtained due to the brain contrast adaptation capability since similar element in a digital imaging system exhibited visible reduction in contrast.
Incurable retinal degenerations affect millions worldwide. Stem cell transplantation rescued visual functions in animal models of retinal degeneration. In those studies, cells were transplanted in subretinal "blebs". A limited number of cells could be injected and photoreceptor rescue was restricted to areas in proximity to the injection sites.To develop a minimally-invasive surgical system for stem cell transplantation in the subretina and extravascular spaces of the choroid.A novel syringe with flexible needle and adjustable pin was developed. Human bone marrow mesenchymal stem cells [hBM-MSCs) were transplanted in the eyes of RCS rats and NZW rabbits through a longitudinal triangular scleral incision. No immunosuppressants were used. Retinal function was determined by electroretinogram analysis and retinal structure was determined by histological analysis and optical coherence tomography (OCT).Transplanted cells were identified as a thin layer across the subretina and extravascular spaces of the choroid. In RCS rats, cell transplantation delayed photoreceptor degeneration across the entire retina and significantly enhanced retinal functions. No changes in retinal functions were recorded in rabbits following transplantation. No retinal detachment or choroidal hemorrhages were observed.The novel syringe facilitates cell transplantation across the subretina and extravascular spaces of the choroid using a minimally-invasive procedure. Human BM-MSC transplantation using this system ameliorates retinal degeneration in the animal model.This new transplantation system may increase the therapeutic effect of other cell-based therapies and therapeutic agents. This study is expected to lead directly to phase I clinical trials for autologous hBM-MSCs transplantation in patients with retinal degeneration.
A survey was made of 205 patients admitted to hospital for ocular trauma in Malawi in south-east Africa from January 1976 to December 1977. Results of the survey show that eye trauma is a relatively common problem in this developing country, occurring most frequently in children, young adults, and males. Most eye injuries in Malawi occurred under domestic circumstances; the major cause of ocular trauma was associated with chopping and gathering wood. Industrial injuries were rare. The most common injury was contusion and the most frequent complication was traumatic cataract. Most treated eyes retained useful vision.
We have evaluated the acute effects of Argon laser injury to the retinal nerve fiber layer (NFL) in the non-human primate. Single Argon laser exposures of 150 millijoules were employed to induce retinal NFL injury. Retinal NFL injury is not acute; unlike its parallel in retinal disease it has two components that emanate from the acute retinal injury site. The ascending component is more visible, primarily because it is ascending toward the disk, representing ganglion cell axons cut off from their nutrient base, the ganglion cell body; the descending component may require up to 3 weeks to develop. Its characterization depends on the distribution of retinal NFL and the slower degeneration of the ganglion cell bodies. Fluorescein angiography suggest a retinal capillary loss that occurs in the capillary bed of the retinal NFL defect. It may reflect a reduced capillary vascular requirement of the NFL as well as a possible reduction of activity in the axonal transport mechanisms in the ascending NFL defect.
We created double perforating injuries in both eyes of 24 rabbits. Into the vitreous cavity of one eye of each rabbit we injected 1 mg 5-fluorouracil (5-FU). After 2 months the eyes treated with 5-FU showed significantly less intraocular proliferation than the saline-treated control eyes.
This paper introduces a new concept and method for long-term sterile storage of turbid product, which is potentially subject to microbial contamination. The method uses intermittent delivery of pulsed electric fields (IDPEF) throughout the storage at time intervals that are prescribed according to microorganisms' growth kinetics. This new approach facilitates sterile storage without the need for chemical preservatives, additives, radiation or the complex infrastructure demanded by refrigeration. Unlike ultraviolet radiation, IDPEF can be used in turbid media. The first part of this paper is a theoretical discussion on the growth kinetics of microorganisms treated by IDPEF. We then provide a preliminary experimental study on the kinetics of microorganism growth in a turbid microbial growth media as a function of the IDPEF delivery intervals. Last, we demonstrate the use of the method using milk as a medium. IDPEF of 30 pulses, 17.5 kV/cm field strength, 40 long, 1 Hz delivered every 12 h was found to have the ability to preserve milk in a non-sterile environment at room temperature as effectively as refrigeration at 4 . The method has many obvious applications in biotechnology, the food industry, and is of particular importance with regard to geographical areas lacking refrigeration for storage of pharmaceuticals and food. This study was performed on the laboratory scale and a substantial adaptations are required in order to apply it to the industrial scale.
