ophthalmology Flashcards
What is conjunctivitis?
Conjunctivitis, also known as ““pink eye,”” is a common condition that involves inflammation or infection of the conjunctiva, the transparent membrane that lines the eyelid and covers the white part of the eye. This condition can be either infectious (caused by bacteria or viruses) or noninfectious (due to allergies or other irritants).
What are the three main types of conjunctivitis?
Allergic
Viral
Bacterial
What type of hypersensitivity reaction is allergic conjunctivitis?
Type I hypersensitivity
What is viral conjunctivitis most often caused by?
adenoviruses (65-90%) but can also be caused by herpes simplex virus. It is highly contagious and often associated with upper respiratory tract infections or colds. This is the most common acute infectious cause.
What common pathogens cause bacterial conjunctivitis?
Common pathogens include Staphylococcus aureus, Staphylococcus epidermis, Streptococcus pneumoniae and Haemophilus influenzae. Sexually transmitted infections like gonorrhoea or chlamydia can also cause bacterial conjunctivitis, so it is important to take a sexual history if suspected.
What are common signs and symptoms of conjunctivitis?
Eye redness
Itching
Irritation
Excessive tearing
Discharge from the eyes, which can vary in consistency based on the cause. For example viral aetiologies produce a more watery discharge, wheres bacterial causes produce purulent discharge.
Photophobia, which suggests corneal involvement (keratoconjunctivitis)
What should notably not be affected by conjunctivitis?
Visual acuity
What are red flag symptoms for a more serious cause of red eye?
Reduced visual acuity
Marked eye pain, headache, photophobia
Red sticky eye in a neonate
History of trauma or foreign body
Rapidly progressive discharge
Infection with herpes virus
Contact lens use
Pupil abnormalities or pain on constriction
Loss of red reflex
Blood or pus in the anterior chamber
What are the investigations for conjunctivitis?
The diagnosis of conjunctivitis is typically based on the patient’s history and physical examination. In certain cases, conjunctival swabs for bacterial cultures may be taken, particularly if the patient does not respond to initial treatment, presents severe or unusual symptoms, or in cases of suspected gonococcal or chlamydial conjunctivitis.
What is the management for allergic conjunctivitis?
Patients are advised to avoid allergens when possible and may be prescribed artificial tears, topical antihistamines, or mast cell stabilisers such as topical sodium cromoglycate.
1st line: topical mast cell stabilizer (sodium cromoglycate) and topical antihistamine (antazoline).
In this light, think of mast cell stabilisers as the ‘preventer’ of allergic conjunctivitis and antihistamines as the ‘reliever’
What is the management for viral conjunctivitis?
As this form is self-limiting, treatment focuses on symptom relief and prevention of spread through good hygiene practices.
What is the management for bacterial conjunctivitis?
This form is also generally self-limiting, but in severe cases, topical antibiotics like chloramphenicol and fusidic acid may be recommended.
How to manage conjunctivitis associated with contact lens wear?
Conjunctivitis associated with contact lense wear should be managed with an aminoglycoside (e.g. gentamycin) or a quinolone (e.g. levofloxacin or moxifloxacin), to cover for gram -ve organisms. Patients should immediately stop wearing contact lenses until symptom resolution and antibiotic course completion.
When should patients be told to seek further medical attention with conjunctivitis?
if their condition worsens or fails to improve after a week of treatment.
If there is evidence of any red flag signs (see above), patients should be referred urgently to ophthalmology.
What is prulent discharge and unilateral stomps a sign of in conjunctivitis?
bacterial infection whereas serous discharge is a more a sign of viral or allergic conjunctivitis
What is optic neuritis?
Optic neuritis (ON) is an inflammatory condition of the optic nerve that often results in visual impairment and ocular pain.
Who mostly gets optic neuritis?
Optic neuritis predominantly affects adult women and is often the first clinical presentation of multiple sclerosis (MS).
What causes optic neuritis?
caused by inflammatory demyelination
Multiple Sclerosis (MS): The most common cause of demyelinating optic neuritis.
Neuromyelitis Optica (NMO): A demyelinating disease that can also affect the optic nerve, presenting similarly to MS-related optic neuritis but with distinct pathophysiology.
Autoimmune disorders: Disorders such as lupus or sarcoidosis can trigger optic nerve inflammation.
Infections: Viral or bacterial infections, particularly those affecting the central nervous system, may lead to optic neuritis.
What are the signs and symptoms of optic neuritis?
Acute, painful vision loss: This is often the hallmark symptom and can range from mild to severe.
Periocular pain: Pain around the eye, especially with eye movement
Dyschromatopsia: Loss of colour vision, particularly red desaturation
Relative afferent pupillary defect
Additional features may include impaired contrast sensitivity and visual field defects.
What are the investigations for optic neuritis?
Visual function tests: To assess visual acuity, color vision (especially red desaturation), and visual fields. Even after recovery, some deficits in contrast sensitivity, color vision, or visual fields may persist.
MRI of the brain and spine: To detect demyelinating lesions, particularly in cases associated with multiple sclerosis or neuromyelitis optica - definitive investigation
Lumbar Puncture: May be required if a diagnosis of Multiple Sclerosis (MS) is considered to assess for paired Oligoclonal Bands (OCB).
What is the management for optic neuritis?
Intravenous methylprednisolone is the first-line treatment for optic neuritis, based on the Optic Neuritis Treatment Trial (ONTT).
Although oral steroids are sometimes used, they have been associated with an increased risk of relapse in some studies.
What is the prognosis of optic neuritis?
The prognosis for optic neuritis is generally good, with most patients regaining near-normal visual acuity within six months.
However, some may continue to experience subtle deficits in color vision, contrast sensitivity, or visual fields.
Which drug is strongly associated with optic neuritis?
ethambutol
What is orbital cellulitis?
a sight- and life-threatening emergency. It describes infection of the structures behind the orbital septum.
What is the orbital septum?
a membranous sheet that forms the anterior border of the orbit, extending from the orbital rims (superior and inferior) and into the eyelids.
What is preseptal cellulitis?
Preseptal cellulitis refers to infection of tissue anterior to the orbital septum. It is much more common than orbital cellulitis and 80% of cases occur in children under the age of 10 years.
Photo of typical scleritis:
More diffuse across the eye
