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The AN/PSQ-42 Enhanced Night Vision Goggle-Binocular (ENVG-B) is a third-generation passive binocular night vision device developed for the United States Army by L3Harris. It combines dual tube image-intensifying (I²) and thermal-imaging technologies into a single goggle, enabling vision in low-light conditions.
A myodisc or myopic disk is a corrective lens with a steep concave curvature that is fitted on the posterior surface of a carrier lens, or a high power single-vision lens specially ordered with slab-off the edge, creating a central prescription disc. These are used for correction of extremely high myopia often seen in low vision patients. [1]
This can be corrected with convex lenses, which cause light rays to converge prior to hitting the cornea. [14] Presbyopia: When the flexibility of the lens declines, typically due to age. The individual would experience difficulty in near vision, often relieved by reading glasses, bifocal, or progressive lenses. [15]
Visual or vision impairment (VI or VIP) is the partial or total inability of visual perception.In the absence of treatment such as corrective eyewear, assistive devices, and medical treatment, visual impairment may cause the individual difficulties with normal daily tasks, including reading and walking. [6]
The add segment of the lens for near vision is the D-shaped area. A bifocal is a lens with two sections, separated by a line (see image to the right). Generally, the upper part of the lens is used for distance vision, while the lower segment is used for near vision. The area of the lens that caters to near vision is called the add segment.
Corrective lenses provide vision correction over a range as high as +4.0 diopters. People with presbyopia require a convex lens for reading glasses; specialized preparations of convex lenses usually require the services of an optometrist. [15] Contact lenses can also be used to correct the focusing loss that comes along with presbyopia.