Anterior eye 3 - Cornea Flashcards
What are the 6 layers of the cornea?
• Epithelium: barrier, attached to basement membrane by hemidesmosomes
• Basement membrane
• Bowmans membrane
• Stroma
• Descemets membrane
• Endothelium: maintains clarity by acting as hydration pump
Endothelium is:
• Cell layer that pumps and hydrate to maintain corneal clarity
• Born with finite amount of cells
What types of injury can occur to the cornea?
• Corneal abrasion
• Recurrent Corneal erosion
• Blunt eye injury
• Penetrating eye injuries
What are the Hyphaema grades?
• Grade 1: 1/3 or 25mm
• Grade 2 : 1/3-1/2
• Grade 3 : 1/2 - near total
• Grade 4 : Total = eightball
How do iris defects occur?
• Object penetrates cornea + iris, may be small or large.
What types of iris injuries can occur?
• Penetration
• Prolapsed iris
What are some examples of globe trauma?
• Globe perforation : high velocity injury with laceration, do not squish eye
How are keratitis measured on the cornea?
• Central or Periphery
• Infectious or sterile
- Central most likely infectious, peripheral most likely sterile
What is marginal keratitis:-
• Immune mediated inflammation caused by blepharitis and lid margin disease
• Small discrete infiltrate
• Peripheral
• Always tends to be close to where lids touch cornea
Where do ocular surface infections come from?
• Opportunistic exposure and
contact
• Airborne
• Finger
• Contact lenses
• Extension from lids
• Upper respiratory tract infection
• Sexual contact
What are the different types if keratitis?
• Herpes Simplex Virus
- Epithelial Keratitis
- Stromal Keratitis
- Uveitis
- Lids to retina
• Herpes Zoster Ophthalmicus
What are the symptoms and signs of herpes simplex viral keratitis?
• Symptoms
- Foreign body sensation
- Photophobia
- Redness
- Blurred vision
• Epithelial ulcer
- Dendritic pattern
- Terminal bulbs
- Swollen adjacent epithelium
What are some signs of HSV keratitis? (During vs post)
• Reduced corneal sensation
- Focal or diffuse
• Conjunctival Injection
• Underlying stromal oedema
• After resolution
- stromal scarring
- Ghost dendrite
Optom Management of HSV keratitis?
• Referral of acute episodes with no history
• Recurrent cases:
- Clear diagnosis
- Only epithelial involvement
- Commence topical antiviral therapy
• Refer if non-healing after 1 week or if there is stromal involvement
What are the chemical treatments of HSV keratitis?
• Topical antiviral therapy
- Acyclovir 3% ointment 5 times daily
- Review one week
- Therapy longer than 2 weeks induces keratopathy
• Debridement with cotton bud
• Oral acclovir
- 800mg 5 times daily
- Maintenance dose of 400mg 2 times daily in recurring disease
• Topical steroids must be discontinued
What is HSV Disciform keratitis?
• Endotheliitis
• Often has circular legion
• Associated uveitis
How is HSV Stromal Keratitis treated?
• No epithelial defect, only stromal
Herpetic eye disease therapy :
• Oral antiviral - Acyclovir
• Topical steroid - Pred Forte
- reduces persistence/ progression
- Shortens duration
- long term prophylaxis
What is HZO - Herpes Zoster Opthalmicus
• SHINGLES!
• Reactivation of latent virus
• Associated with altered immunity
• Zoster dermatitis
- Vesicular rash
- General malaise
- Multitude of ophthalmic signs
What are the symptoms of herpes zoster?
•Dermatological
- Pain / paraesthesia / rash
- Distribution
- Extension over scalp
- Duration
•Headache, Fever, Lethargy
• Ocular
- Blurred vision
- Eye pain / photophobia
- Red eye
- Discharge
What are the dermatological signs of Herpes Zoster Opthalmicus?
•Vesicular skin rash
•Typically cranial nerve V1 distribution
•Can occur V2 or V3
•Unilateral, obeys midline
•Hutchison sign - rash on tip of nose
What are eyelid signs of Herpes Zoster Opthalmicus?
•Cicatricial changes in previous cases and lid malposition
•Lid oedema causing ptosis
•Lagophthalmos - beware of corneal exposure
•Trichiasis
What are conjunctiva signs of Herpes Zoster Opthalmicus?
•Mucopurulent discharge
•Hyperaemia
•Petechial Haemorrhage
•Papillae or follicular conjunctivitis
•Pseudomembrane
What are corneal signs of Herpes Zoster Opthalmicus?
•Exposure keratopathy
•Punctate erosions
•Dendritic type lesions (tapering ends compared to bulbs seen in HSV keratitis)
•Disciform keratitis. Can occur after rash.
•Neurotrophic keratitis
•Peripheral corneal ulceration
•Secondary infective keratitis
•Epithelialitis and keratitic precipitates associated with uveitis
Inflammatory signs of Herpes Zoster Opthalmicus?
• Uveitis
- Usually presents 1 week after onset of rash
- Anterior chamber activity
- Keratitic precipitates and epithelialitis
• Episcleritis / Scleritis
- Injection of superficial or deep scleral vessels
- Associated nodular lesion
• Dilated Fundal Examination
- Vitritis
- Retinitis / Choroiditis
What examinations are performed for herpes zoster?
•Relevant dermatological
•Visual acuity
•Pupil assessment
•Intraocular pressure
•Corneal sensation
•Ocular adnexa
•Slit lamp anterior segment
•Dilated fundal examination
What other signs can be found during examination for Herpes Zoster?
• Optic neuropathy
- Reduced visual acuity
- Swollen, hyperaemic optic disc
• Ocular motility palsy
- Palsy of cranial nerve I, IV & VI can occur
- Assess pupil responses and orbicularis function if llIrd palsy suspected
Comparison of Herpes simplex and Zoster:-
• Dendrites
- HSV. Central ulceration with terminal bulbs. Geographic if steroids used
- VZV. Smaller without central ulceration or terminal bulbs
• Dermatomal distribution - zoster
• Skin scarring - after rash; zoster
• Neuralgia; zoster
• Iris atrophy; zoster has iris atrophy
• Recurrent disease
Management of Herpes Zoster?
• Rest and supportive advice
• Avoid contact with immunocompromised patients
- Consider elderly, infants, pregnant females
• Epithelial disease - lubricants
• Analgesia
• Limited to epithelium - manage joined by GP
• Referral if deeper layers involved
• Acyclovir : 800mg 5times daily, 1 week course is the ideal chemical treatment
What is bacterial keratitis?
• Sight and eye threatening condition
• Variable speed of onset
• Rapid onset with significant inflammation
• Can progress to corneal perforation
• Requires urgent referral
What are the causes of bacterial keratitis?
• Associated with epithelial disruption
• Contact lens wear
• Trauma
• Contaminated topical ocular medications
• Impaired defence mechanisms
• Altered structure of corneal surface
Contact lens related keratopathy management?
• Discontinue of lens wear 2-14 days
• Advice against extended wear
• Lid hygiene in presence of blepharitis
• Appropriate type of contact lens wear
• Refer if infective component suspected
Clinical symptoms of corneal ulcer/bacterial keratitis?
• Rapid onset of pain
• Conjunctival injection
• Photophobia
• Decreased vision
• Rate of progression depends on virulence of organism
What are bacterial keratitis ulcers?
• Sharp epithelial demarcation
• Underlying dense, suppurative stromal inflammation
• Indistinct edges surrounded by stromal oedema
• Presentation can vary from quick onset and aggressive course to slow, indolent course
What are pseudomonas?
• Bacterial keratitis infection
• Pseudomonas typically produces stromal necrosis with a shaggy surface and adherent mucopurulent exudate
• Endothelial inflammatory plaque
• Marked anterior chamber reaction
• Hypopyon
What are the different types of slow growing bacterial keratitis?
• Slow growing, fastidious organisms
- Mycobacterium
- Anaerobes
- Non-suppurative infiltrate
- Intact epithelium
What are non-vision threatening bacterial keratitis treatment strategy?
• 1mm or less depth
• Topical Quinolones - broad spectrum
- Ofloxacin
- Ciprofloxacin
• 1 - 2 hourly
• Cyclopentolate 1% TDS
• Review within 48 hours
• Tapering as usual
• Mild topical steroids once infection controlled +/- organism identified
What are vision threatening bacterial keratitis treatment strategy?
• Consider admission
• Hourly: Antibiotics
- Preservative free Gentamicin 1.5%
- Taper after 48 hours
• Cycloplegic
• Systemic antibioics
- Oral ciprofloxacin 750mg BD
Signs of improvement for corneal ulcers?
• Blunting of perimeter of infiltrate
• Decreased density of stromal infiltrate
• Reduction of stromal edema
• Reduction of anterior chamber activity
• Epithelial recover
• Cessation of corneal thinning
What is fungal keratitis risk factors?
• Less common
• Warmer, more humid areas
• Predisposing risk factors
- Trauma to cornea
- Contamination with organic material
- Topical steroid use
• Gardeners
• Immunocompromised
What are the signs and symptoms of fungal keratitis?
• Fewer inflammatory signs and symptoms in initial stage
• Minimal conjunctival injection
• Filamentous fungus
- Gray-white infiltrate with feathery margins - May elevate corneal surface
- Satellite lesions may be present
- Endothelial plaque + hypopyon with rapid
progression
• Candida
- superficial white lesions
Management of fungal keratitis
• Very difficult
• Initial treatment probably for bacterial keratitis until diagnosis proven by biopsy
• Most commonly used is Amphoteracin B
What causes Acanthomaeba infection?
• Protozoa
• Commonly associated with contact lens wear and swimming
How does an Acanthamoeba presented?
• Severe pain disproportionate to signs
• Initial punctate keratopathy or dendrite
• Ring ulcer
• Diagnosed by corneal scrape
• Suspected if non-responding to conventional bacterial keratitis therapy
Management of Acanthamoeba?
• If Px doesn’t seem to respond from bacterial treatment - suspect
• Urgent referral
• Stop contact lens wear and bring with solution for culture
• Corneal scrape
• Topical amoebicides
• Topical steroids - wait 1 month after amoebicides
What is neutrophic keratitis?
• Reduced corneal sensation due to break down of epithelium and break down of cornea.
- example : HSV keratitis
Stage 1 neutrophic keratitis symptoms?
• Punctate corneal epithelium
• Superficial vascularisation
• Stromal scaring
• Decreased tear break up time
• Increased tear mucus viscosity
• Epithelial hyperplasia and irregularity
• Hyper-plastic pre corneal membrane
• Staining of palpebral conjunctiva with rose bengal
Stage 2 neutrophic keratitis?
• Epithelial defect, usually in superior half of cornea
• Smooth and rolled epithelial defect edges
• Surrounding rim of loose epithelium
• Stromal oedema
• Anterior chamber inflammation
What is stage 3 neutrophic keratitis?
• Corneal ulcer
• Stromal staining
• Perforation
What are some types of epithelial/anterior corneal dystrophies? (7)
• Map dot fingerprint dystrophy
• Meesmann’s epithelial dystrophy
• Bowmans layer dystrophies:-
- Reis-Bucklers corneal dystrophies
• Lattice Dystrophy (anterior stroma)
• Granular dystrophy
• Macular corneal dystrophy
• Central cloudy dystrophy
What are some types of posterior corneal dystrophies?
• Posterior polymorphous dystrophy
- Grey opacities close to descemets membrane
What are some types of endothelial corneal dystrophies?
• Guttata ; hazes cornea due to failure of pump
• Fuchs endothelial dystrophy
• CHED - congenital hereditary endothelial dystrophy
• Ectasia : abnormal distortion of shape of cornea, i.e keratoconus
How to detect keratoconus?
• Scissor reflex
• Fleischer ring
• Corneal topography
What is acute hydrops?
• Caused by thinking of corneal so much whereby fluid flows rapidly into stomal layer causing haze
Keratoconus management?
• Maximise level of vision
- Start with glasses, progress to contact lenses
- In severe cases, corneal transplantation
• Halt progression
- Teens/20’s the disease progresses the most
- Can try stabilise cornea by strengthening bonds of cornea
What is band keratopathy?
• Calcium deposits under epithelium
- can break structural integrity of cornea
• Can be removed by debrideing cornea with cotton bud using EDTA solution
What is salzmanns nodular degen?
• Greyish hazy pacifications nodules that is associated with ocular surface disease, such as dry eye
• Can have epithelial breakdown
What is penetrating keratoplasty?
• Corneal transplantation
- whole thickness of cornea removed and replaced
What is the penetrating keratoplasty technique?
• Superficial anterior lamellar keratoplasty
• Deep anterior lamellar keratoplasty (stroma)
• DSAEK - replaces descemets membrane/endothelial membrane
What are risks of keratoplasty?
• Graft rejection
- Is manageable if treated properly, failure to treat may result in need to repeat transplantation
- Khoudadoust line is a sign of rejection
