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Retinal hemorrhage (UK English: retinal haemorrhage) is a disorder of the eye in which bleeding occurs in the retina, the light sensitive tissue located on the back wall of the eye. [1] There are photoreceptor cells in the retina called rods and cones , which transduce light energy into nerve signals that can be processed by the brain to form ...
Other factors can cause glaucoma, known as "secondary glaucoma", including prolonged use of steroids (steroid-induced glaucoma); conditions that severely restrict blood flow to the eye, such as severe diabetic retinopathy and central retinal vein occlusion (neovascular glaucoma); ocular trauma (angle-recession glaucoma); plateau iris; and ...
A phosphene is the perception of light without light actually entering the eye, for instance caused by pressure applied to the closed eyes. A phenomenon that could be entoptical if the eyelashes are considered to be part of the eye is seeing light diffracted through the eyelashes.
In a technique known as blue field entoptoscopy, the effect is used to estimate the blood flow in the retinal capillaries.The patient is alternatingly shown blue light and a computer generated picture of moving dots; by adjusting the speed and density of these dots, the patient tries to match the computer generated picture to the perceived entoptic dots.
A subconjunctival hemorrhage appears as a bright red patch on the white of the eye and is commonly referred to as a burst blood vessel. In hyphema, blood pools in the anterior chamber, where the iris (the colored part of the eye) and the pupil are located. Hyphemas are graded based on the amount of blood covering the cornea.
Temporary vasospasm leading to decreased blood flow can be a cause of amaurosis fugax. [14] [15] Generally, these episodes are brief, lasting no longer than five minutes, [16] and have been associated with exercise. [10] [17] These vasospastic episodes are not restricted to young and healthy individuals. "Observations suggest that a systemic ...
The blood–ocular barrier is a barrier created by endothelium of capillaries of the retina and iris, ciliary epithelium and retinal pigment epithelium. [1] It is a physical barrier between the local blood vessels and most parts of the eye itself, and stops many substances including drugs from traveling across it. [2]
Light energy enters the eye through the cornea, through the pupil and then through the lens. The lens shape is changed for near focus (accommodation) and is controlled by the ciliary muscle. Between the two lenses (the cornea and the crystalline lens), there are four optical surfaces which each refract light as it travels along the optical path.