2 - Retinal Fundus Examination Flashcards
What structures in the eye are transparent? (to allow light to reach the retina)
- cornea
- aqueous humor
- lens
- vitreous jelly
Why is administration of mydriatc drugs an essential part of optical exams?
- pupil must be widely open to examine the retina properly
What structures make up the posterior segment of the eye?
= posterior 2/3 of eye
- hyaloid membranes
- vitreous hummer
- retina
- choroid
- optic nerve
What structures make up the retinal fundus?
- retina
- optic disc
- macula
- fovea
What is the macula?
- most sensitive part of retina
- majority of photoreceptors concentrated here
- maximal visual resolution
What is the vitreous? Where is it & what is its role?
= jelly substance
- provides shape, volume & nurtures the eye
- behind crystalline lens
What is the vitreous made of?
- mainly water (98%), collagen type II, glycosaminoglycans, hyaluronan, opticin
What gives the vitreous its transparency?
- fine organization of collagen fibres –> allows light to reach retina w. no interference
What encapsulates the vitreous humor ?
What is the refractive index & viscosity of vitreous humor compared to that of water?
What is myodesopsia?
What is photopsia?
What is Posterior Vitreous Detachment? Causes?
What are the visual symptoms of Posterior Vitreous Detachment?
What are some conditions that cause alterations of virtuous transparency? (4)
- Posterior vitreous detachment
- Uveitis - with recruitment of immune cells and their consequent accumulation
- Invasion of the structure by WBCs - autoimmune or infective diseases
- Neoplastic Diseases - secondary or primary vitreoretinal lymphomas.
- Bleeding/ Haemorrhage
What is the most common cause of vitreous opacification? Explain the pathophysiology.
What is the most common cause of haemorrhage in the eye? And other causes?
most common = posterior vitreous detachment
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What structures can be seen at the optic disc?
What features of the optic disc are evaluated in an optical exam?
What is the cup-to-disc ratio?
What is optic atrophy?
What is a megalodisc?
What is acute papilledema?
What is hypotony (hypotonic maculopathy)?
What is the function of the optic nerve, how is it evaluated?
What is a paracentral scotoma?
What is the macula (in detail)?
The macula has a ____ metabolic rate, which clears oxidative metabolic products to avoid toxic damage to photoreceptors.
high
What is age related maculopathy (AMDnv)?
Which exams allow us to observe age related maculopathy?
What is Tamoxifen maculopathy?
What is Chloroquine maculopathy?
What is optic coherence tomography/OCT? How does it work?
- non-invasive anatomic reconstruction of retina
- uses lightwaves to take cross sectional retinal pics –> to see single cells
- based on INTERFEROMETRY
- light source emits infrared waves & send them to the machine –> light is split into a part that reaches a reference mirror & part that reaches the eye by a beam splitter
- echoes from the eye & ref mirror are detected & combined by a photodetector
- even tho the penetrance is lower than US the resolution is amazing
What are the new models of OCT machines?
- Swept-source OCT - diff wavelength & thus increased penetrance
- Adaptive-Optics OCT
What is retinal fluorangiography?
- multimodal imaging technique
- Sodium fluorescin dye injected IV –> mainly binds to albumin (high affinity)
- hypersensitivity reactions are rare except –> jaundice w/ yellow discolouration of sclera may occur in 1st 24h
What is the principle behind retinal fluorangiography?
What is the blood retinal barrier?
Which 3 patterns can be observed on retinal fluorangiography?
What is Indocyanine green retinal angiography?
Clinical implications of Indocyanine green retinal angiography.
What is fundus autofluorescence (FAF)?
Which pathologic deposits have their own fluorophores?
What are the (4) possible findings in fundus autofluorescence (FAF)?
Clinical applications of fundus autofluorescence (FAF)?
