Ophthalmology Flashcards
What is the macula?
Central vision area of the retina, darker than the rest of the retina.
Lateral to the optic disc
Has the highest visual acuity
What is the fovea?
Centre of the macula, rod free
What is the normal intra occular pressure?
10-21mmHg
How is the aqueous humour drained?
85 % conventional- via the Canal of Schlemm into the anterior chamber angle
15% uveoscleral- into the ciliary circulation
What is emmetropia?
No refractive error. Light rays from infinity brought to focus on the retina
What is myopia?
Short sightedness, light rays from infinity brought to focus in FRONT of the retina. Eye is too long, or lens too strong.
What is index myopia?
Short sightedness where the lens of the eye is too strong.
What is axial myopia?
Short sightedness where the eyeball is too long.
What is hypermetropia?
Long sightedness; eyeball too short or lens too weak.
What is astigmatism?
Eyeball rugby shaped, so has stronger power in one direction than another.
What happens in accommodation?
The ciliary muscle CONTRACTS, and the suspensory ligaments become LOOSE. The lens becomes CONVEX (thicker)
What are the key features of primary open angle glaucoma? (POAG)
- Raised intraoccular pressure >21
- Cupped optic disc
- Visual field loss
- Open drainage angle
What are the symptoms of POAG?
Usually asymptomatic
Visual field loss is a late sign
Painless
What are the risk factors for POAG?
Age Diabetes Corticosteroids Myopia (short sightedness) Inherited
What medical eye drop treatments can be used for POAG?
Eye drops:
- Prostaglandin analogues eg. Latanorprost which increase uveoscleral outflow
- Beta blockers eg. Timolol which decrease aqueous production
- Carbonic anhydrase inhibitors which decrease aqueous production
- Alpha agonists eg. Brimondine which increase outflow and decrease production
What is Blepharitis?
Chronic eyelid inflammation; can be due to S.aureus infection or gland blockage. Is the most common cause of acute red eye, and presents with red eye, crusty eyelid, blocked Meibornian glands and Meiborninan cysts.
What is the most common cause of acute red eye?
Blepharatis- inflammation of the eyelid, caused by bacteria eg. Staph aureus, or gland blockage.
Presents with red eye, crusty eyelashes, blocked Meibornian glands and Meibornian cysts.
Treated with warm compress, sodium bicarb or antibiotic ointment.
What is a stye?
Infected hair follicle, which may be pus filled.
What is an entropian?
Eyelid turned inward, eyelashes rub on the cornea. Is usually genetic, and requires surgery.
What is herpes ophthalmicus?
Reactivated varicella zoster virus (shingles) affecting CNV (nasocilliary branch).
What are the 5 causes of conjunctivitis?
- Bacterial- S.aureus, Strep or Haemophilus
- Viral- more contagious
- Chlamydial- unilateral red eye in a young male, requires systemic antibiotics
- Allergic- type 1 hypersensitivity reaction
- Cicatrising- causes scarring due to physical, infection, drugs, or systemic disorders
What is keratitis and what are the causes?
Inflammation of the cornea: Bacterial, viral, autoimmune
What is bacterial keratits and how is it treated?
Bacteria causing corneal inflammation, resulting in corneal abscess, photophobia, cells in the anterior chamber and reduced vision. Ophthalmic emergency.
What are the risk factors for bacterial keratitis?
Contact lenses
Corneal abrasion/ anaaesthetics
Bacteria near eye
Topical steriods
Which eye condition has Inflammation of the white of the eye, often idiopathic, and may have have scleral thickening leading to a blue black discolouration?
Scleritits
What is uveitis?
Inflammation of the iris.
Red eye, usually aged 20-50 years with no discharge
Which condition has red eye with no discharge, miosis, cells in the anterior chamber, flare and posterior synechiae?
Uveitis
What is acute angle closure glaucoma?
Sudden painful vision loss, with a dilated pupil and the aqueous humour can’t drain. This usually occurs in hypermetropia (long sightedness)
What are the signs of acute angle closure glaucoma?
Increased intraoccular pressure >60
Nausea and vomitting
Headache
Reduced vision
What is orbital cellulitis?
An ophthalmic emergency, which can track via the optic nerve to the brain. Infection of muscle and fat within the eye orbit.
What are the risk factors for macular degeneration?
Age
Smoking
Family History
What is macular degeneration?
Gradual loss of central vision, may be progressive over years. First symptom is visual distortion, and peripheral vision is maintained.
There is difficulty reading and recognising faces.
What are the two forms of macular degeneration?
- Dry- 90%, age related atrophy leading to central vision loss
- Wet- 10%, neovascularisation of the retina (choroidal neovascularision) leading to new vessels penetrating into the retina and causing bleeding and scarring. This is more severe than dry AMD
What are “drusen”?
Macular lesion
Soft drusen- pale yellow, large with poorly defined edges, progresses to AMD
Hard drusen- yellow with well defined margins,not always associated with AMD
What are the treatments for dry AMD?
Can’t stop or reverse visual loss
Vitamins- zinc and antioxidants help prevent visual loss in the other eye
What are the treatments for wet AMD?
Photodynamic therapy
Anti vEGF- injected into vitreous cavity
How is orbital cellulitis treated?
IV antibiotics and urgent CT scan
How does Herpes Ophthalmicus present?
Forehead tingling
Eye pain
Oedema
Photophobia
What presents with Increased intraoccular pressure >60, nausea and vomitting, headache and reduced vision?
Acute angle closure glaucoma
What presents with an unwell patient, reduced eye movement, proptosis (foreward eye movement) and sinusitis?
Orbital cellulitis
What presents with corneal abscess, photophobia, reduced vision, cells in the anterior chamber?
Bacterial keratitis
Which eye condition is associated with Ankylosing spondolytis?
Uveitis
How is bacterial keratitis treated?
Corneal scrape to gram stain.
Sterilisation using Fluroquinolone.
Haling using topical steroids.
How is Herpes Ophthalmicus treated?
Antivirals
Topical steriods.
