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Colour, where the retina is illuminated by white light and examined in full colour. Red free fundus photography utilizes a filter in order to better observe superficial lesions and some vascular abnormalities within the retina and surrounding tissue. A green filter ~540–570 nm is used to block out red wavelengths of light.
Mydriasis is the dilation of the pupil, usually having a non-physiological cause, [3] or sometimes a physiological pupillary response. [4] Non-physiological causes of mydriasis include disease, trauma, or the use of certain types of drug.
When the test is performed in an eye with an afferent pupillary defect, light directed in the affected eye will cause only mild constriction of both pupils (due to decreased response to light from the afferent defect), while light in the unaffected eye will cause a normal constriction of both pupils (due to an intact efferent path, and an ...
Blue–red contrast demonstrating depth perception effects 3 Layers of depths "Rivers, Valleys & Mountains". Chromostereopsis is a visual illusion whereby the impression of depth is conveyed in two-dimensional color images, usually of red–blue or red–green colors, but can also be perceived with red–grey or blue–grey images.
The red reflex (also called the fundal reflex) refers to the reddish-orange reflection of light from the back of the eye, or fundus, observed when using an ophthalmoscope or retinoscope. The red reflex may be absent or poorly visible in people with dark eyes, and may even appear yellow in Asians or green/blue in Africans. [1]
Dilation and constriction of the pupil. Pupillary response is a physiological response that varies the size of the pupil, via the optic and oculomotor cranial nerve.. A constriction response (), [1] is the narrowing of the pupil, which may be caused by scleral buckles or drugs such as opiates/opioids or anti-hypertension medications.
Image credits: John Shearer/Getty Images He added: “She looks healthier and there is obvious weight loss between the May photo and the more recent one. “Her neckline and jawline now really pop ...
To see it, one needs to look at the right edge of a small red light in a dark room with the right eye (left eye closed) after dark-adapting for about 30 seconds; one should see two faint blue arcs starting at the light and heading towards the blind spot.