China
Africa
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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
Corneal Disorders
Published in Ching-Yu Cheng, Tien Yin Wong, Ophthalmic Epidemiology, 2022
Darren S. J. Ting, Rashmi Deshmukh, Daniel S. W. Ting, Marcus Ang
The cornea is a vital transparent structure that forms “the front window of the eye,” playing a key role in vision and ocular surface defense. Corneal damage from insults such as infection, inflammation, and trauma can lead to corneal opacity and resultant visual impairment. According to a recent World Health Organization (WHO) report, corneal opacity represents the fifth leading cause of blindness globally.1 It is estimated that around 4.2 million people were suffering from moderate to severe visual impairment secondary to corneal diseases in 2019.1 More importantly, avoidable corneal blindness has been shown to be significantly more prevalent (up to 90% of all blindness) in developing countries such as Africa (for example, Ethiopia), Myanmar, and many others, primarily attributed to poor sanitation, malnutrition, lower educational level, and limited access to healthcare facilities.2–4
Ageing
Published in Henry J. Woodford, Essential Geriatrics, 2022
Cataracts are opacities in the crystalline lens of the eye, which can cause blurred vision, increased susceptibility to glare and difficulty seeing in low light conditions. Affected people may also report seeing haloes around lights. Smoking, high alcohol intake and radiation exposure increase the risk of cataract development. They can increase the probability of accidents (including falls), impair function and lower quality of life. Surgery becomes appropriate when they are causing significant symptoms. The lens is extracted under local anaesthetic and replaced with an artificial one (termed ‘pseudophakia'). Serious complications are rare.
Effect of Anti-TNF Treatment on Mooren’s Ulcer: A Case Series and Review of the Literature
Published in Ocular Immunology and Inflammation, 2023
Annie Xia, Tina Dietrich-Ntoukas, Uwe Pleyer
We observed in all of our patients, who were unresponsive to previous treatment, a recovery of corneal findings after treatment with anti-TNF agents. Further progression of corneal melting was prevented, and inflammatory activity including conjunctival hyperemia and neovascularization of the cornea was reduced. The first response was seen in all patients following the first two infusions, while ocular inflammation was totally controlled within 3–6 months. Clearing of corneal stroma was notable with significant thinning of the remaining cornea but without further epithelial defects. No perforation occurred during the follow-up. Insufficient recovery of vision in some eyes was due to fast progression of the corneal destruction with irregular astigmatism and a conjunctivalized ocular surface. In addition, co-morbidities such as uncontrolled glaucoma (patients 1 and 5) and cataract formation (patients 1 and 3) due to high-dose steroid treatment limited the functional outcome.
A Review of Lens Biomechanical Contributions to Presbyopia
Published in Current Eye Research, 2023
Presbyopia is caused by aging of the ocular lens which results in the loss of accommodative function. The term presbyopia is derived from ancient Greek and loosely translates to “old man eye.” This is a fitting description of the condition since nearly all people can expect to encounter presbyopia as they age.1,2 Presbyopia is characterized as the loss of accommodative power which presents clinically as the inability to focus vision on nearby objects and a long time to focus. Symptoms are typically noticed some time after the age of forty with complete loss of objective accommodation occurring between the ages of 50–55 years old.3 Alarmingly, decline in accommodative ability begins in adolescence and can be reduced by up to 50% by age 25.4 Accommodation is typically entirely lost after about two thirds of a human lifespan, which is a much shorter time course than many other physiologic functions.5,6 This is significant because symptoms of this age associated pathology can be expected to begin in middle age and without prevention or treatment will hinder patients’ vision for an extended portion of life.
Collision avoidance behaviours when circumventing people of different sizes in various positions and locations
Published in Journal of Motor Behavior, 2021
Sheryl M. Bourgaize, Bradford J. McFadyen, Michael E. Cinelli
Vision is an important sensory modality during navigation as it provides the observer with information to anticipate and react to physical hazards within the environment (Patla, 1997). Successful navigation through an environment requires humans to visually perceive objects and their properties to strategically manoeuvre around them and other individuals. Fajen and Warren (2003) suggests that modelling the behavioural dynamics of human locomotion demonstrate that locomotor trajectories emerge from simple navigation laws. This framework is often used to describe human avoidance behaviours and is referred to as the Behavioural Dynamics Model (Fajen, 2013; Fajen & Warren, 2003; Warren, 2006). The assumption of the Behavioural Dynamics Model is that goal-directed behaviours could be predicted based on angles and distances of the observer, the obstacle(s), and the goal. The model suggests that individuals treat obstacles like repellors and the goal like an attractor until the gap between the obstacles is large enough to negate the repulsion effects of the obstacles but enhance the attractiveness of the goal. The model is widely used throughout research regarding collision detection, interception, and obstacle avoidance, providing a simple explanation for the visual control of human locomotion. However, there are some limitations associated with the model; the model does not consider the physical size of the person or objects, action capabilities, or the manner in which locomotor speed and direction are coordinated (Fajen, 2013).