The best treatment for cataract patients, which allows to restore clear vision is implanting an artificial intraocular lens (IOL). The image quality of the lens has a significant impact on the quality of patient’s vision. After a long exposure the implant to aqueous environment some defects appear in the artificial lenses. The defects generated in the IOL have different refractive indices. For example, glistening phenomenon is based on light scattering on the oval microvacuoles filled with an aqueous humor which refractive index value is about 1.34. Calcium deposits are another example of lens defects and they can be characterized by the refractive index 1.63. In the presented studies it was calculated how the difference between the refractive indices of the defect and the refractive index of the lens material affects the quality of image. The OpticStudio Professional program (from Radiant Zemax, LLC) was used for the construction of the numerical model of the eye with IOL and to calculate the characteristics of the retinal image. Retinal image quality was described in such characteristics as Point Spread Function (PSF) and the Optical Transfer Function with amplitude and phase. The results show a strong correlation between the refractive indices difference and retinal image quality.
Detection of vision defects of a child without professional knowledge is not easy. Very often, the parents of a small child does not know that their child sees incorrect. Also the youngster, not knowing any other way of seeing, does not know that it is not the best. While the vision of a small child is not yet fully formed, it is worth checking them very early. Defects detected early gives opportunity for the correction of anomalies, which might give the effect of the normal development of vision. According to the indications, the American Optometric Association (AOA) control eye examination should be performed between the ages of 6 months to 3 years, before going to school and then every two years. Members of SPIE Student Chapter, in cooperation with the Visual Optics Group working on the Department of Optics and Photonics (Faculty of Fundamental Problems, Wroclaw University of Science and Technology) for 6 years offer selected kindergartens of Wroclaw participation in project “Screening vision tests in pre-school children”. Depending on the number of involved members of the student chapter and willing to cooperate students of Ophthalmology and Optometry, vision screening test was carried out in up to eight kindergartens every year. The basic purpose of screening vision test is to detect visual defects to start the correction so early in life as possible, while increasing the efficiency of the child's visual potential. The surrounding community is in fact more than enough examples of late diagnose vision problems, which resulted in lack of opportunity or treatment failure
Disorder of color vision in humans is the inability to perceive differences between some or all of the colors that are normally perceived by others. Color blindness is usually a birth defect, a genetically determined. For this reason it is much more common in men than women. This paper presents the results of the test FarnsworthD-15 and Lanthony D-15 on a group of volunteers, both adults and children. The study was conducted to compare the results of both tests.
The color vision has been described as one to be very sensitive to the intake of several chemicals. The present research reviews the published literature that is concerned with color vision impairment due to alcohol. Most of this research considers people under long-term effects of alcohol. However, there is little information about temporary effects of alcohol on color vision. A group of ten volunteers aged 18-40 was studied. During the study levels of alcohol in the body were tested with a standard breathalyzer while color vision were studied using Farnsworth Munsell 100 Hue Color Vision Tests. Keywords: Col
After a few weeks a newborn baby can recognize high contrasts in colors like black and white. They reach full color vision at the age of circa six months. Matching colors is the next milestone. Most children can do it at the age of two. Good color vision is one of the factors which indicate proper development of a child. Presented research shows the correlation between color vision and visual activity. The color vision of a group of children aged 3-8 was examined with saturated Farnsworth D-15. Fransworth test was performed twice - in a standard version and in a magnetic version. The time of completing standard and magnetic tests was measured. Furthermore, parents of subjects answered questions checking the children’s visual activity in 1 - 10 scale. Parents stated whether the child willingly watched books, colored coloring books, put puzzles or liked to play with blocks etc. The Fransworth D-15 test designed for color vision testing can be used to test younger children from the age of 3 years. These are preliminary studies which may be a useful tool for further, more accurate examination on a larger group of subjects.
Intraocular lens (IOL) is an artificial lens implanted into the eye in order to restore correct vision after the removal
of natural lens cloudy due to cataract. The IOL prolonged stay in the eyeball causes the creation of different changes
on the surface and inside the implant mainly in form of small-size local defects such as vacuoles and calcium deposites.
Their presence worsens the imaging properties of the eye mainly due to occurence of scattered light thus deteriorating
the vision quality of patients after cataract surgery. It is very difficult to study influence the effects of these changes
on image quality in real patients. To avoid these difficulties two other possibilities were chosen: the analysis of the image
obtained in an optomechanical eye model with artificially aged IOL as well as numerical calculation of the image
characteristics while the eye lens is burdened with adequately modeled defects.
In experiments the optomechanical model of an eye consisting of a glass “cornea”, chamber filled with liquid
where the IOL under investigation was inserted and a high resulution CCC detector serving as a “retina” was used.
The Modulation Transfer Function (MTF) of such “eye” was evaluated on the basis of image of an edge. Experiments
show that there is significant connection between ageing defects and decrease in MTF parameters.
Numerical part was performed with a computer programme for optical imaging analysis (OpticStudio Professional,
Zemax Professional from Radiant Zemax, LLC). On the basis of Atchison eye model with lens burdened with defects
Modulation Transfer Functio was calculated. Particular parameters of defects used in a numerical model were based
on own measurements. Numerical simulation also show significant connection between ageing defects and decrease
of MTF parameters. With this technique the influence of types, density and distribution of local defect in the IOL
on the retinal image quality can be evaluated quickly without the need of performing very difficult and even dangereous
experiments on real human patients.
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