Flashcards in Ocular Pathology Deck (27)
What are the three physiological barriers which isolate the eye from systemic circulation?
1. Blood aqueous barrier
2. Inner blood-retinal barrier
3. Outer blood-retinal barrier
These barriers consist of tight junctions between vascular endothelial cells in the iris and retina, and between cells of the ciliary body and retinal pigment epithelium.
Together, these barriers help control the composition of intraocular fluids and environment.
Why is use of topical steroids so common in ophthalmology?
To suppress ocular inflammation, as inflammation in the eye (contrary to most parts of the body) can be destructive and may lead to cataract, glaucoma, macular oedema, retinal detachment and corneal scarring, amongst others.
Which three major parts of the eye are avascular?
Cornea, lens, and vitreous.
What two types of processes may result in abnormal vascularisation of the eye?
Inflammation and ischaemia (amongst others).
Eg. Vessels (not blood?) in cornea can leak lipid and cause opacity.
Eg. Vessels at the vitreoretinal interface can bleed (vitreous haemorrhage) or contract (retinal detachment).
What is an example of successful repair (healing) which results in functional failure?
The consequences of corneal infection.
The transparent cornea is opacified by invasion of inflammatory cells in response to presence of micro-organisms. As pathogens are cleared, keratocytes lay down and remodel ECM which is disorganised and therefore no longer transparent.
Name an immunologically privileged site.
The normal cornea.
Ie. will normally tolerate the presence of foreign antigen.
Name three pathological consequences of diabetic retinopathy (and hypertension) which lead to physical signs seen on ophthalmoscopy.
2. Vessel incompetence (leakage)
3. Vessel occlusion (ischaemia)
Name three angiopathic consequences of atherosclerosis which may lead to loss of neural function in the eye.
1. Ischaemic optic neuropathy (blindness)
2. Visual pathway "stroke" (field defect)
3. Extraocular muscle nerve palsy (double vision)
What is frequently the primary site for ocular manifestation of systemic inflammatory (often autoimmune) disease?
The uvea (choroid, ciliary body, iris).
Anterior uvea is most common site of involvement. Inflammation gives the clinical syndrome of 'iritis' with protein exudation and cellular invasion into the anterior chamber.
Posteriorly, choroidal inflammation disrupts normal retinal function.
Retinal vasculitis and corneoscleral destruction may also occur.
Which of the types (I, II, III, IV) of hypersensitivity reactions (allergy) can affect the eye?
All of them.
Hay fever is an example of what type of hypersensitivity?
Atopic keratoconjunctivitis is due to what type of hypersensitivity reaction?
Mixture of type I and type IV.
Frequently leads to corneal and conjunctival disruption and scarring.
What is a chalazion?
A chronic granulomatous inflammatory nodule which surrounds fat-filled spaces and arises as a consequence of meibomian gland blockage.
What are xanthelasmata?
Dermal collections of lipid which may be associated with hyperlipidaemia.
What is a dermoid?
A cyst-like lump which results from imperfect fusion of embyronal skin flaps.
These are lined by squamous epithelium and are filled with keratin. A dermoid may extend backwards deep into the orbit.
What could swelling of the lacrimal gland be due to?
Inflammation, benign tumour, malignant tumour.
Eg. Benign pleomorphic adenoma of the lacrimal gland (which may recur if not completely removed at operation).
Which structures within the orbit can give rise to a benign or malignant space-occupying lesion?
Any structure within the orbit.
What is the most common benign orbital tumour in childhood?
What is a rare and aggressive malignant tumour of extraocular muscle occurring in childhood, which may mimic orbital cellulitis?
Name four space-occupying lesions of interest in the orbit.
1. Varices (enlargements of pre-existing venous channels).
3. Cavernous haemangioma
Name the two main tumours occurring within the eye.
Melanoma and retinoblastoma.
Retinoblastoma, a malignant tumour of the retina, has cells which characteristically group into clusters known as what?
Is retinoblastoma spontaneous or inherited?
Most occur sporadically in childhood but some are inherited as autosomal dominant defects, in which case they are often bilateral. There is a high incidence of second primary tumours in other sites.
Lymphoproliferative infiltrations may occur within the eye and mimic what?
They may also occur in the conjunctiva and within the orbit, diffusely or in the lacrimal gland. On histological exam, some are frankly malignant.
True or false: the eye and orbit are frequently sites for metastatic spread from distant malignancies.
Tumours of the lung, breast, gastrointestinal tract, kidney and prostate are common sources.
True or false : histological examination is necessary to confirm the clinical diagnosis of most lumps in and around the orbit.