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Questions for part A
Published in Henry J. Woodford, Essential Geriatrics, 2022
Which of the following conditions is the commonest cause of irreversible sight loss among older people?Age-related macular degenerationCataractsDiabetic retinopathyGlaucomaPresbyopia
Screening Programs
Published in Ching-Yu Cheng, Tien Yin Wong, Ophthalmic Epidemiology, 2022
Jakob Grauslund, Malin Lundberg Rasmussen
Screening of sight-threatening diseases is an important task in ophthalmic care. This chapter has conceptualized the term of ocular screening and provided clinical examples of impact and challenges in this area. With a globally aging population and recent technological landmarks in hand, the ground has been laid for future ways to combat blindness in various ocular diseases.
Central nervous system
Published in A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha, Clark’s Procedures in Diagnostic Imaging: A System-Based Approach, 2020
A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha
The eye is the special sense organ of sight (Figs 11.52a,b). It is situated in the orbital cavity, surrounded by adipose tissue that affords protection from trauma. It is almost spherical with an anterior bulge, comprising three layers: an outer fibrous layer, a middle vascular layer and an inner nervous layer. It contains three substances: the aqueous humour, the lens and the vitreous humour. The outer fibrous layer forms a complete sphere, the anterior one-sixth is known as the cornea and the posterior five-sixths the sclera. It has no blood supply but derives its nourishment from lymph. The middle vascular layer forms nine-tenths of a sphere incomplete anteriorly. It comprises the choroid, ciliary body and the iris. The innermost layer forms three-quarters of a sphere (posteriorly) and is known as the retina. This has an outer pigmented layer and an inner nervous layer. It contains special cells designed for vision – rods and cones. The optic disc (or blind spot) is that part of the retina where the optic nerve enters the eyeball.
Disparities in Access to Corneal Tissue in the Developing World
Published in Seminars in Ophthalmology, 2023
Catherine Liu, Hajirah N. Saeed
Corneal disease is a major cause of blindness worldwide, currently ranking fourth after cataract, glaucoma, and age-related macular degeneration.1 In 2020, 43.3 million people were estimated to be blind using the World Health Organization’s (WHO) definition of blindness as best corrected vision worse than 3/60 (20/400) in the better seeing eye.1,2 Of these, 4.2 million cases of blindness were attributable to corneal opacity and an additional 2 million cases are secondary to trachoma.1 In developing countries, corneal disease may represent the second leading cause of blindness,3 which is disproportionately higher than in other countries. In certain regions of Africa, as much as 90% of all blindness is attributable to corneal pathology4; however, availability and access to cornea tissue, which can often cure corneal blindness, in these parts of the world is dismal compared to industrialized countries. In contrast, the US has the highest rate of corneal transplantation, with the greatest amount of corneal procurement and transplantation per capita worldwide.5 There exists a significant disparity between countries when it comes to access to cornea tissue, with supply often inversely proportional to burden of disease.6 There are many variables and challenges that perpetuate this disparity. This review will discuss those factors as well as highlight how reduction in corneal blindness and access to sight saving cornea tissue may be attainable.
Changes in corneal and anterior chamber indices due to methamphetamine abuse
Published in Clinical and Experimental Optometry, 2022
Monireh Mahjoob, Samira Heydarian
These changes could include mild/no symptoms and severe loss of vision and endophthalmitis, which may lead to a permanent loss of sight.5,6 There is a relatively small body of the literature that is concerned with meth-induced ophthalmic complications.5,7–10 These adverse effects include keratitis, ischaemia, retinal vasculitis, emboli, episcleritis, vasoconstriction, oedema, scleritis, crystalline retinopathy, central retinal artery occlusion, intra-retinal haemorrhages, corneal ulceration, as well as transient vision losses. Furthermore, direct sympathetic stimulation by meth leads to acute pupillary dilation as well as blurred vision as a result of decreased accommodation.11,12 Pupil dilation can lead to acute angle closure glaucoma in individuals with shallow anterior chambers.8,13 Besides, peripheral effects of amphetamines, which mainly come through their α and β1 and β2 adrenergic agonist properties, mediate characteristics including vasoconstriction, coronary dilatation, and bladder contraction. Therefore, regardless of the dose or blood concentration, the heart rate accelerates, and blood pressure rises.14,15 An increase in heart rate and blood pressure can bring about a long-term increase in fluid pressure in the eye and, consequently, glaucoma.16
Summarizing the medieval anatomy of the head and brain in a single image: Magnus Hundt (1501) and Johann Dryander (1537) as transitional pre-Vesalian anatomists
Published in Journal of the History of the Neurosciences, 2022
The remainder of the left-side legend deals with organs of sensation: N. Caru[n]cule (caruncle); O. Visus (sight); P. Audit[us] (hearing); Q. Olfactus (smell); and R. gustus (taste). Caruncle in this case refers to carunculae mammillares (mamillary carnunculae; i.e., olfactory bulbs; see Swanson 2015). These appear almost as a tiny pair of eyeglasses at the bridge of the nose, but instead are the olfactory bulbs and their projections to the brain as olfactory tracts—a visual projection inside the skull to the base of the brain.8This interpretation is supported by Dryander’s later figure, which had a more detailed and clearer legend. Sight (i.e., the eyes) is indicated with a Gothic majuscule O (resembling a standard D) under each eye. Hearing and smell are indicated by Gothic majuscules P in front of the ear, and Q over the lower portion of the nose, respectively. Taste is indicated by an upside-down Gothic R on the tongue.