Test Your Eyes
Light - House
A Low Vision Department
"Patients with no vision and low vision are treated here"
Light House is dedicated to helping people off all ages overcome the challenges of vision loss and is a modern rehabilitation center for people of all ages and different needs ranging from Low Vison to NO vision who cannot be further treated with surgery, medicine and refraction.
Light House, a strong voice for visually impaired people for their full inclusion into the mainstream society.
Miss Mehreen Tanveer (Light House manager)
ParamedicsZubair Ahmed (Refractionist)
Afshan Iqbal (Nursing Assistant)
Aleena Anjum (Ophthalmic Technician)
What is Low Vision
" The World Health Organization (WHO 1992) describes a person with low vision as "one who has an impairment of visual function, even after treatment and/or standard refractive correction, and has a visual acuity of less than 6/18 [the metric equivalent of 20/70] to light perception or a visual field of less than ten degrees from the point of fixation, but who uses, or is potentially able to use, vision for the planning and/or execution of a task." WHO maintains 5 levels of vision loss from low vision of 20/70 to no light perception .While many definitions include clinical measures of acuity or visual field, Corn and Koenig (1996) describe these various definitions as arbitrary, given that there is no assurance that a person with a specific clinical measure will or will not be able to complete specific tasks that do not require the recognition of letters or symbols at specified distances. Their expressed concern is what is often referred to as functional vision and may vary within the same individual based on factors such as lighting, fatigue or glare.
The Visual System
The visual system is made up of three basic parts: the eyes, the optic nerve, and the brain. Specific visual elements that assist in building a visual image include central visual acuity, peripheral (side) vision, binocular vision (which aids with depth perception), night vision, color vision and contrast sensitivity. The eye works very much like a camera, with light coming into the eye through the cornea and traveling through the lens of the eye with the iris functioning as an aperture to moderate the amount of light allowed to enter the eye. The light waves are bent by both the cornea and the lens so that they converge at a specific point on the retina, called the macula. If they do not converge exactly in the right place, the person may need glasses or contact lenses to assist them in seeing clearer. The retina is the tissue which holds the photoreceptor cells (like the film of a camera) and covers the inside of the rear chamber of the eye. The photoreceptor cells (rods and cones) and their attached network in the retinal pigment epithelium are where the light rays are changed into neural-electric impulses that travel along the optic nerve to the occipital lobe of the brain. What an individual actual sees is composed of image, color, and movement, and is put together in the brain. Damage anywhere along the optic pathway from the cornea of the eye to the brain can cause vision impairment.
No matter the cause of vision loss, how an individual uses their remaining vision can vary tremendously from person to person or in different environments. Additional personal and environmental factors affecting the interpretation of vision include factors such as fatigue, personality, experience, novelty, complexity, lighting, contrast, and glare. These factors can enhance or complicate the individual's interpretation of what is seen. For children with vision loss, learning to interpret their environment is one of the challenges of having low vision and often requires specialized instruction.
Magnitude and Causes of Visual Impairment
According to the World Health Organization (WHO 2004), visual impairment is not distributed uniformly throughout the world. More than 90% of the world's visually impaired live in developing countries, and in every region of the world, females have a significantly higher risk of being visually impaired than males (WHO 2004). In spite of sometimes crude methods of assessing vision loss, WHO also estimated worldwide prevalence of people who have a significant visual disability at approximately 135 million (Whitcher 2008). Except for the most industrial countries, cataract remains the leading cause of blindness in all regions of the world and when associated with aging, it is even more significant as a cause of low vision. Other major causes of low vision worldwide include glaucoma, age-related macular degeneration, trachoma, onchocerciasis (river blindness), Hanson's Disease (leprosy), malnourishment (vitamin A deficiencies), diabetic retinopathy, and other corneal opacities (WHO 2004).
It is widely agreed that unemployment and underemployment are major problems for men and women who have low vision. Because approximately 90% of people with visual impairments have some useful vision, low vision devices and rehabilitation services offer opportunities to enhance their visual and functional capacities. In developing countries, there are special challenges to low vision service delivery.
Who Treated in Light House
People having following problems can benefit from Light House Services
Low Vision Devices
Many people with low vision can benefit from either changes in the environment (lighting, adding contrast, or reducing clutter and glare) or the use of low vision devices. People with low vision vary dramatically in their ability to successfully use magnification devices for near and distance vision tasks. Their ability will vary based on age, visual condition/eye disease, amount or ability to use their residual vision, etc. Low vision devices are frequently categorized as optical (near & distance magnification) and non-optical devices.
In Light House learning techniques in eccentric viewing, and sensory integration can assist people with low vision to use their residual vision more effectively. Proper selection and training in the use of different optical and non-optical aids can also enhance the use of low vision so that an individual can use their remaining vision more effectively.
Overview of Low Vision Devices
Optical devices, Near-vision magnification
Any optical device that magnifies the image for viewing tasks within 18 inches. These devices incorporate the use of specific lenses, generally convex or plus lenses.
Used primarily for near tasks within arm's reach, such as reading, writing, sewing, playing board games, and crafts.
Examples of Devices
Handheld magnifier Stand magnifier Spectacle lenses Mirror magnifier Telemicroscope.
Any optical system that magnifies the size of an image for viewing tasks from 12 inches to infinity. These devices incorporate the use of both convex and concave lenses.
Used primarily for distance tasks beyond arm's reach, such as spotting street signs, viewing sporting events, or watching television.
Examples of Devices
Handheld telescope, Spectacle-mounted telescope, Behind-the-lens telescope
A device that does not involve the use of corrective lenses (convex or concave). Many nonoptical devices do not involve magnification.
Used in near and distance tasks to enhance environmental features, such as illumination and contrast, to sustain visual functioning and to control visual fatigue.
Examples of Devices
Lighting color filter, Large-print material, Reading stands
A device that magnifies the size of an image through the use of lenses and electronic enhancement. The size of the image is increased as it is projected.
Used primarily for near and distance tasks that require greater magnification and flexibility in adjusting contrast and illumination.
Examples of Devices
Microcomputer screen, Closed-circuit television, Low Vision, Enhancement System
Software's for Blind and Low Vision Patients
Jaws is a full range of screen reading and screen magnification software, notetakerss, Braille displays, and other devices for blind and visually impaired computer users. With the help of JAWS users can access a whole world of information, education, and job-related applications for browsing the WEB, reading or writing e-mail messages, working with spreadsheets, or accessing information in a database. This software is the product of choice for blind and visually impaired people around the world.
MAGIC is a software solution ideally suited for computer users with low vision, or anyone who spends extended periods of time in front of a computer screen.
Close Circuit Television (CCTV)
Video magnifiers (also known as closed circuit television systems or CCTVs) are some of the more sophisticated and powerful magnifying tools available to workers with low vision. They may be necessary for some tasks when a hand-held or stand magnifier (a prescribed optical device) will not work; Video magnifiers consist of a video camera connected to some type of monitor such as a computer monitor.
Optelec (clear View):
Clear View is an auto-focus desktop video magnification system, designed to assist people with low vision. Clear View enables you to enjoy reading, writing, viewing photos, doing hobbies, crafts and lots more.
SARA (Scanning and Reading Appliance)
SARA is a standalone device designed to help the blind and those with low vision read printed materials. You can use SARA to read almost anything, including mail, important documents, hardcover and paperback books, and more. SARA uses the latest in optical character recognition technology to scan pages and then reads the contents of that page to you with clear, crisp, human-sounding synthesized speech. SARA contains a host of features that let you customize your reading experience. A built-in CD drive lets you read your favorite books on CD. SARA even allows you to read DAISY (Digital Accessible Information System) format digital talking books.
ONYX Flex - ARM PC Edition
The ONYX camera makes seeing printed type, pictures, handwriting, and small details easier than ever before.
OPAL is a portable video magnifier that lets you magnify printed text from three to six times its actual size. OPAL has been designed with special attention to the practical needs of those with macular degeneration, glaucoma. RP, cataract, and other causes of low visionThe OPAL is easy to use, even for those unfamiliar with assistive technology. You turn the power on with one button, place it over an object, and adjust the magnification to your preference with the Magnification slider. The magnified image appears in the display window
OPAL features a bright, high contrast 4-inch LCD screen with scratch-resistant cover, six video modes, rechargeable battery, and writing stand. You can even connect OPAL to a television if you need a larger viewing area.
The TOPAZ Desktop Video Magnifier makes seeing printed type, pictures, handwriting, and small details easier than ever before. Just place a letter or picture on the moveable reading table, and adjust the magnification level and the display colors to work best for your eyesight. Your document display in large size on the screen.
TOPAZ includes the following features:
This introduction to low vision is designed to expose the reader to the visual system and provide resources or leads on where to go for additional information. Understanding the task-specific visual difficulties that persons with low vision may face can be difficult and confusing. Knowing how to resolve those difficulties can likewise require a vast array of knowledge and experts in a variety of areas. It is hoped that this chapter can serve as a valuable resource and help improve one's understanding of low vision and how it can impact the individual.