Opthalmology Flashcards
Learning objectives
Answer
Define cataracts
• Opacification of the lens of the eye
Explain the aetiology/risk factors of cataracts
• Most are IDIOPATHIC (age-related)
• Secondary Causes
o Local: previous eye trauma, uveitis
o Systemic: diabetes, metabolic (e.g. Wilson’s disease), skin disease (e.g. scleroderma), drugs (e.g. steroids)
o Congenital: congenital rubella syndrome
Summarise the epidemiology of cataracts
• Major cause of treatable blindness worldwide
Recognise the presenting symptoms of cataracts
- Gradual-onset painless loss of vision
- Glare from bright light
- Vision may worsen in bright light
- Some may experience monocular diplopia with haloes around lights
- Some may begin to be able to read without glasses (a sclerotic cataract may increase the lens’ converging power)
Recognise the signs of cataracts on physical examination
- Loss of red reflex
- Hazy lens appearance
- Reduced visual acuity
Identify appropriate investigations for cataracts
• Usually unnecessary
Define Conjuctivitis
Conjunctivitis is a common condition that causes redness and inflammation of the thin layer of tissue that covers the front of the eye (the conjunctiva).
Explain the aetiology / risk factors of conjunctivitis
Causes Viruses Bacteria Allergies A chemical splash in the eye A foreign object in the eye In newborns, a blocked tear duct
Risk factors:
Exposure to something for which you have an allergy (allergic conjunctivitis)
Exposure to someone infected with the viral or bacterial form of conjunctivitis
Using contact lenses, especially extended-wear lenses
Summarise the epidemiology of conjunctivitis
Affects 2% annually. Viral is most common
Recognise the presenting symptoms of conjunctivitis
Infective conjunctivitis
If you have infective conjunctivitis, you may also have:
a burning sensation in your eyes
a feeling of grit in your eyes
a sticky coating on the eyelashes – usually when you first wake up in the morning
an enlarged lymph node (gland) in front of the ear
Allergic conjunctivitis
You may have itchy eyes if you have allergic conjunctivitis.
The pattern of symptoms for allergic conjunctivitis depends on the substance you’re allergic to.
Allergies to pollen (hay fever) occur during certain parts of the year. You can have an allergy to:
tree pollen, released during spring
grass pollen, released during the end of spring and beginning of summer
weed pollen, released any time from early spring to late autumn
Recognise the signs of conjunctivitis on physical examination
When symptoms are mild, a diagnosis of viral conjunctivitis can often be made without seeing a doctor, and the condition can be treated at home.
Identify appropriate investigations for conjunctivitis and interpret the results
Based on symptoms, microbial culture
Define glaucoma
• Optic neuropathy with typical field defect usually associated with ocular hypertension (intra-ocular pressure > 21 mm Hg)
Explain the aetiology/risk factors of glaucoma
Primary Causes
o Acute closed-angle glaucoma (ACAG)
o Chronic closed-angle glaucoma
o Primary open-angle glaucoma (POAG)
Secondary Causes o Trauma o Uveitis o Steroids o Rubeosis iridis (formation of new blood vessels on the surface of the iris)
Congenital o Buphthalmos (enlargement of the eye balls)
Pathophysiology of Glaucoma
o Ocular hypertension leads to compression and stretching of the retinal nerve fibres
o This leads to scotomas (partial loss of vision) and visual field defects
o Ocular hypertension is due to reduced outflow of aqueous humour caused by:
• AOAG: Obstruction to the outflow (caused by narrowing of the iridocorneal angle and, hence, narrowing of the canal of Schlemm leading to a rapid and severe rise in IOP)
• POAG: Resistance to the outflow through the trabecular meshwork
• Blockage of trabecular meshwork by blood or inflammatory cells
Summarise the epidemiology of glaucoma
• Prevalence:
o 1% in over 40 yrs
o 10% in over 80 yrs
• 3rd most common cause of blindness worldwide
