Eye Pathology Flashcards
What are the three broad classes of causes of red eye? What are major examples of each?
- life-threatening: skull fracture with subconjunctival hemorrhage, conjunctivita neonatorum, scleritis, neoplasms
- sight-threatening: glaucoma, uveitis, keratitis, gonococcal conjunctivitis, penetrating and chemical eye trauma
- common: subconjunctival hemorrhage, foreign body, conjunctivitis, dry eyes
What should we suspect in repeated episodes of red eye in the same eye? What about if the red eye spreads to both eyes? What about painful red eye? What about with a watery discharge? A purulent one?
- repeated episodes of same eye: herpes simplex keratitis (both eyes: allergic)
- rapid spread to both eyes: viral conjunctivitis
- painful: glaucoma, penetrating eye injury, foreign body
- watery: viral infection
- purulent: bacterial infection
What is the most common cause of red eye in the elderly? How does this present? How do we treat it?
- MCC in elderly is subconjunctival hemorrhage
- presents as a unilateral painless red eye
- most are self-limiting and don’t require any treatment
- if it’s following trauma, it can be a potential serious injury
What is conjunctivitis and how does it present? What are the common causes?
- conjunctivitis is inflammation of the eye limited to the conjunctiva
- it presents as a unilateral painless red eye that may progress to bilateral involvement; can be irritating and gritty
- common causes are allergy, viral (MC is adenovirus), and bacterial
- allergy: recurrent, bilateral itchy and watery eyes
- virus (MCC): rapid bilateral involvement, highly contagious, watery discharge, periauricular lymphadenopathy
- bacteria: purulent discharge, highly contagious
What is the local anesthetic test and what does its results mean?
- this is the application of a local anesthetic eye drop
- it is used to determine if a painful red eye is due to a more superficial cause (abrasions, breaks in the corneal epithelium) or a deeper cause (uveitis)
- if it’s superficial, the pain will be relieved
What is the purpose of fluorescein dye?
- fluorescein dye will change any abrated/ulcerated areas a yellow-green color
What are the major causes of ocular herpetic disease?
- this is caused by viruses
- major viruses: herpes simplex (HSV) and herpes zoster (VZV)
- other viruses: EBV and CMV
What type of viruses are herpes viruses (HSV and VZV)? Where do these remain latent in infected individuals? What percent of the population carries the virus?
- herpes viruses are DNA viruses
- they can remain latent in the sensory ganglia (commonly in that of the trigeminal nerve/CN V)
- 90% of the population carries the latent virus!
What type of ocular herpetic disease does herpes simplex virus cause?
- HSV causes dendritic keratitis
- this is characterized by TRUE dendritic lesions (they show arborization and terminal end bulbs)
- HSV can follow multiple nerve branches
- the recurrence is more frequent than in VZV, but the episodes are shorter in duration
What type of ocular herpetic disease does herpes zoster virus cause?
- VZV causes herpes zoster ophthalmicus
- characterized by PSEUDO dendritic lesions (vs. HSV, which causes true dendritic lesions)
- VZV tends to follow a single nerve branch (classically V1 if it is to affect the eyes)
- the recurrence is less frequent than in HSV, but the episodes are longer in duration
What are common causes of sudden loss of vision?
- carotid occlusive disease (ophthalmic artery branches from the carotid), embolism, vasculitis; these all result in retinal ischemia (retinal ischemia is indicated by a cherry red spot - a prominent macula in the setting of ischemia - on fundoscopy)
- damage to optic nerve, chiasm, tract, etc.
- glaucoma
- migraine
What are the four leading causes of vision-reducing eye disease in the elderly?
- age-related macular degeneration (ARMD): loss of central vision
- glaucoma: increased pressure damages optic nerve
- cataracts: now treated successfully with surgery
- diabetic retinopathy
What is age-related macular degeneration? How do patients present? What are the two forms of the disease?
- ARMD (or just AMD) is the leading cause of vision loss in patients over 65
- the macula degenerates, resulting in a loss of central vision (complete blindness does not occur)
- patients present with blurred vision, image distortion, central scotoma, and difficulty reading
- 2 forms of the disease: dry and wet
Compare dry vs. wet macular degeneration.
- dry AMD is much more common (90% of cases) and less severe than wet AMD; symmetrical gradual deposits of extraocular material (called drusen) in both macula
- wet AMD is less common (10%), but is responsible for most cases of severe vision loss; wet AMD is an extension of dry AMD and is characterized by abnormal choroidal vessels (choroidal neovascularization), leading to leakage of fluid and blood into the macula
What is glaucoma? How do patients present? How do we treat it?
- glaucoma is the most common cause of blindness in black Americans
- it results from excess aqueous humor leading to raised intraocular pressures that damage the optic nerve
- patients present with progressive peripheral vision loss that moves centrally, headache, nausea, and eyeballs that are hard on palpation (due to the raised IOP)
- we treat it by decreasing the secretion of aqueous humor by the ciliary body (secretion is a sympathetic response, so we give sympathetic antagonists) and by increasing aqueous outflow into the canal of Schlemm (via parasympathomimetics and PG analogs); can decrease pressure by giving mannitol to promote osmotic diuresis for short-term treatment