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Glaucoma
Published in Charles Theisler, Adjuvant Medical Care, 2023
Glaucoma is a group of eye conditions that damage the optic nerve, leading to loss of vision or blindness. Glaucoma develops often as a result of abnormally high pressure in the anterior chamber of the eye. However, not every person with increased eye pressure will develop optic nerve damage.1 There are two major types of glaucoma: open angle and closed angle. Open angle is the most common form, accounting for 90% of all cases. At first, open-angle glaucoma has no symptoms. It causes no pain and vision stays normal. Nonetheless, over time and without treatment, increased intraocular pressure damages the optic nerve. In closed-angle glaucoma, drainage canals are blocked so pressure in the eye increases. Individuals with glaucoma gradually lose their peripheral (side) vision. If glaucoma remains untreated, objects to the side and out of the corner of the eye can be missed. In more advanced cases, patients often report that their vision is like looking through a tunnel. Over time, central vision may also decrease until no vision remains.1
Refractive Errors, Myopia, and Presbyopia
Published in Ching-Yu Cheng, Tien Yin Wong, Ophthalmic Epidemiology, 2022
Ka Wai Kam, Chi Pui Pang, Jason C. S. Yam
Another global health burden, astigmatism is the second most common refractive error.124 It occurs when light coming in from two different meridians is bent differently and focuses on to two points rather than a single point, resulting in blurred images. One dioptric difference in refractive powers at two meridians constitutes 1 D of astigmatism, which is sufficient to cause meridional amblyopia in children.125 Although other thresholds such as –0.5 D and –0.75 D exist in defining astigmatism, –1.0 D remains clinically relevant as a guide for prescribing spectacle corrections.126 Astigmatism can be categorized into simple myopic, compound myopic, hyperopic, or mixed astigmatism. Astigmatism in an eye is essentially determined by the curvatures of the cornea. Corneal astigmatism refers to the difference in dioptric refraction between the flattest and steepest curvatures of the cornea, whereas overall astigmatism of the eye is further influenced by the shapes of the lens, vitreous humor, and retina. When the axis is located near the horizontal meridian, it is classified as with-the-rule astigmatism, which constitutes the majority of astigmatism phenotypes observed in children. In people aged above 50 years, the axis shifts to around 90°, and this condition is known as against-the-rule astigmatism.
Teager-Kaiser Boost Clustered Segmentation of Retinal Fundus Images for Glaucoma Detection
Published in K. Gayathri Devi, Kishore Balasubramanian, Le Anh Ngoc, Machine Learning and Deep Learning Techniques for Medical Science, 2022
P M Siva Raja, R P Sumithra, K Ramanan
Glaucoma is an eye disease and it leads to blindness. The cruel vision-related diseases are ignored by early identification and accurate treatment of glaucoma. Many researchers are carried out for Glaucoma disease identification. However, segmentation plays a significant task that correctly detects glaucoma.
Physical Activity Self-Efficacy in Older Adults with Vision Loss: A Grounded Theory Study
Published in Occupational Therapy In Health Care, 2023
Beth A. Barstow, Nataliya V. Ivankova, Laura K. Vogtle, Laura Dreer, Brian Geiger, Laurie A. Malone
In industrialized countries, the most prevalent cause of low vision is age-related macular degeneration (AMD) (NEI, 2020). The National Eye Institute (2020) defines age-related macular degeneration as a progressive chronic eye condition affecting the macular area of the retina. The macula, located in the central 20 degrees of the visual field, is composed primarily of cone cells responsible for providing information regarding the color, contrast and detail of objects and environments. Individuals with AMD have difficulty with tasks that require fine-detail vision such as reading, recognizing faces, and detecting low contrast drop-offs such as unmarked curbs (NEI, 2020). Additionally, individuals experience fluctuations in vision, macular scotomas, photophobia, and slow dark/light adaptation (NEI, 2020).
Relationship of Density, Depth, and Surface Irregularity of Superficial Corneal Opacification with Visual Acuity
Published in Current Eye Research, 2023
Vineet Pramod Joshi, Subhajit Chatterjee, Sayan Basu
Irregular astigmatism in eyes with corneal scarring prevents optimal improvement in visual acuity with spectacle correction. Apart from reduction in the visual acuity it also leads to scattering of light, irregular refraction producing glare, and reduced contrast sensitivity.15,16,34 RGP contact lenses (CLs) improve visual acuity by providing a smooth refracting surface thus masking the irregular astigmatism due to scar. The tear film underneath the contact lens may also neutralize surface irregularities. Literature also suggests that RGP CLs can provide significant visual improvement in eyes with nebular and nebulo-macular corneal opacity.14 Contact lens corrected visual acuity (CLCVA) is an indicator of the best possible visual outcome that can be achieved in corneal scarring without any surgical intervention, hence we used the same variable along with difference between BSCVA-CLCVA, baseline UCVA to study the behavior of these specific HOAs at different levels.
Systemic quinolones and risk of retinal detachment I: analysis of data from the US FDA adverse event reporting system
Published in Expert Opinion on Drug Safety, 2022
Mohamed Kadry Taher, Abdallah Alami, Christopher A. Gravel, Derek Tsui, Lise M. Bjerre, Franco Momoli, Donald Mattison, Daniel Krewski
Retinal detachment (RD) is a condition involving the separation of the retinal layer of the eye from the underlying tissues, which may lead to complete loss of vision in the affected eye if not managed immediately [13,14]. This separation takes one of two forms: the more common rhegmatogenous type or the less common exudative type [13,14]. The annual incidence of RD ranges from 5–14 cases per 100,000 population based on results from studies conducted in the US, Japan, Finland, Sweden and Croatia [14–16]. Safety concerns have been raised regarding the possibility of a damaging effect of the quinolone class on the connective tissues in the eye [17], similar to their confirmed effect on the connective tissues in the tendons [4,18,19]. These concerns were heightened by reports on quinolone-associated retinal detachment [20], retinal hemorrhage [18], macular degeneration [21], corneal perforation [22] and optic neuropathy [23]. Three recent studies reported a possible association of quinolone antibiotics with RD risk [14,24,25]. Other epidemiologic studies reported conflicting results on the association of quinolones with risk of RD [26–34].