Common Conditions of The Eye Flashcards
What is the risk associated with the thin walls of the orbit?
Easily fractures leading to herniation of contents into the surrounding sinuses.
What is meant by a blow out fracture?
Bony orbit rim is strong, impact of a ball will transmit to the walls of the orbit and blow out – called a blow out fracture – contents of orbit leak out into adjacent sinus (maxillary sinus) - eye can’t move because there is a tethering effect
Why does a blow out fracture sometimes result in reduced feeling in the lower eyelid, upper lip and part of the nasal vestibule?
Maxillary nerve leaves the infraorbital foramen and is called the infraorbital nerve – fracture often results in palsy of this nerve and so there is reduced feeling in the lower eyelid, upper lip, and part of the nasal vestibule
What is often the cause of orbital fat hypertrophies? (leads to staring appearance)
Occurs in thyroid diseases
A previously well 23 year old woman attended A&E with a two hour history of blurred vision and a red and swollen eye
O/E: red, painful no eye movement. Progressed within an hour to complete loss of vision.
History elicited of having squeezed a pimple near her left nasolabial fold 3 days prior
Infection spread to the cavernous sinus via emissary veins which resulted in cavernous sinus thrombosis - venous drainage from the orbit is compromised since ophthalmic vein drains into the cavernous sinus. There is now compression and paralysis of nerves that pass through the cavernous sinus - nerves 3,4 and 6 pass through cavernous sinus.
Which nerve is responsible for the parasympathetic effect of constricting the pupil?
Third nerve carries parasympathetic effect – constricts pupil
Why does diabetic nerve damage to the oculomotor nerve result in preservation of the parasympathetic function of the pupil reflex?
Parasympathetic fibres run on the surface of the third nerve, diabetic nerve damage is from the inside out. If the pupillary reflex fails it could be as a result of an aneurysm.
Where do the central retinal artery and vein enter the orbit?
Choroidal fissure
What is meant by coloboma?
Normal tissue in or around the eye is missing from birth
Why does a coloboma form?
Failure of fusion of the choroidal fissure before birth?
What parts of the eye can be affected by a coloboma?
Irirs
Retina
Optic disc
Eyelid
Lens
Macula
Optic nerve
Uvea
Why can blunt trauma cause blindness?
The retina next to the ora serrata is very thin and so blunt trauma may result in holes forming here.
Vitreous gel gets liquefied, liquid vetrous pushes through retinal tear and detaches it.
Liquified vitrous should usually separate the 9th and 10th layer of the retina as these layers are not attached
What is the cause of conjunctivitis?
Self-limiting bacterial or viral infection of the conjunctiva
What are the signs and symptoms of conjunctivits?
Red, watering eyes, discharge
No loss of vision so long as the infection doesn’t spread to the cornea, blurry vision may indicate that the infection has spread to the cornea
What is the treatment for conjunctivitis?
Antibiotic eye drops if likely to be bacterial
What can cause the drooping of an eyelid?
LPS elevates the eye
Drooping eyelid means ptosis – think third nerve dystrophy or paralysis
What causes the inability to close an eyelid?
Facial nerve is responsible for the orbicularis occuli muscle - therefore failure to close the eye indicates facial nerve palsy/paralysis
What can happen as a result of dry eyes?
Ulcers form
What are the meibomian glands?
Glands at the rim of the eyelid (within tarsal plate) responsible for the produciton of meibum, an oily substance that prevents evaporation of the eye’s tear film.
What is a hordeolum?
Localised infection or inflammation of the eyelid margin involving hair follicles of the eyelashes or meibomian glands.
The infection of a hordeolum usually is painful, erythematous, and localized
What are the two types of hordeolum / stye?
Internal and exteranl hordeolum
What is the name given to the granuloma of the meibomian glands?
A chalazion
What is the main feature of the chalaizon that makes it distinguishable from the hordeolum?
Chalaizon is painless