Corneal Pathologies Flashcards
Microcysts: Aetiology (6)
Hypoxia stress of the cornea
More prevalent in extended wear or daily wear with low Dk materials
Easily detectable indicator of contact lens induced hypoxia
Non wearers can have corneal microcysts due to other hypoxia related causes
Small number of cysts can be considered normal
In isolation - not a serious threat to epithelial health
Microcysts: Signs (6)
3-50 micron epithelial vesicles (spheroid or ovoid)
Display reversed illumination
Will stain if breaks through epithelial surface (due to increase in numbers)
Can be seen with 15x mag (40x needed to differentiate)
Retro illumination with 45 degrees between illumination and observation is best technique to observe
Will be seen lying in front of the iris/pupil border
Microcysts: Symtpoms (3)
Usually none
If severe, may see mild haze
Lens intolerance if severe
Microcysts: Grading (5)
0: none
1: 1-10
2: 11-30
3: 31-70
4: >70 cysts
Microcysts: Management (8)
Less than grade 2 - monitor unless other signs of oedematous
More than grade 2 - must increase oxygen to cornea
Management will be depend on cause:
- Cease wear until resolves
- Refit with SiHi
- Manage any ocular pathologies adding to oedema
- Review extended wear
- Altering night schedule and not refitting to daily wear is unlikely to improve
- Improve tear pump by changing base curves, edge lift and smaller TB
Microcysts vs Vacuoles (3)
Vacuoles are spherical, fluid-filled cysts
Vacuoles display unreversed illumination
Microcysts display reversed illumination (due to density)
Striae: Aetiology (6)
Lactic acid accumulation and osmotic shift due to hypoxia stress of cornea
More common with diabetes, increased age and keratoconus
More common in extended wear or daily wear with low Dk
Easily detectable sign of contact lens hypoxia
Fluid separation of fibrils with more than 5% oedema
Usually only seen for up to 4 hours after waking
Striae: Signs (4)
Fine white vertical lines
Seen posterior in stroma
Number increases with increase of oedema
Becomes ‘greyer’ and thicker as oedema increases
Striae: Symptoms (1)
None
Folds: Aetiology (5)
Hypoxia stress of a cornea
Causes physical buckling of posterior stroma
More common in non SiHy extended wear or daily wear with low Dk
More common in diabetics, increased age and keratoconus
Seen with more than 8% oedema
Folds: Signs (2)
Long, straight dark lines seen in endothelial mosaic (buckling in posterior stroma)
Direct parallel-piped 25-40x mag or specular reflection is best to view endothelium
Dellen: Signs (4)
Saucer like depression in peripheral cornea
Possible overlying stain
Epithelium intact
Localised neovascularisation and scarring (depends on cause)
Dellen: Symptoms (2)
Usually none
Symptoms linked to causation (dryness or discomfort)
Dellen: Management (4)
Cease lens wear
Usually resolves quickly
Manage any epithelial defect
Resolve causation
Ulcer (1)
Local defect, or excavation of the surface tissue which is produced by sloughing of inflammatory necrotic tissue
Infiltrates (1)
Single or multiple discrete aggregates of grey/white inflammatory cells that have migrated to the corneal tissue
Microbial (1)
Used to refer to an event that us ‘culture positive’ (infective in nature)
Supprative (1)
Used when pus is present (purulent exudate)
Epithelial Break/Defect (1)
Areas of epithelial damage, due to mechanical trauma, desiccation, infection ect
Peripheral (1)
Corneal infiltrative events that occur outside the central 6mm of the cornea
Sterile (1)
Used to refer to corneal infiltrative events where there is no microbial infection within the corneal tissue
Contact Lens Peripheral Ulcer (CLPU): Other names (3)
Sterile infiltrates
Sterile keratitis
Sterile corneal ulcer
Contact Lens Peripheral Ulcer (CLPU): Increased Risk (3)
Blepharitis
Extended wear
Poor case and lens hygiene
Contact Lens Peripheral Ulcer (CLPU): Aetiology (3)
Non-infective inflammatory event.
Bacteria on lens or lid margins produce antigens resulting in corneal response (bacteria does not invade or replicate within the cornea)
No progression to infection or increase risk of MK
Contact Lens Peripheral Ulcer (CLPU): Signs (7)
Peripheral anterior stromal infiltrate (single or multiple)
Usually less than 1mm (can be up to 2mm)
Overlying epithelial stain
Conjunctival Localised hyperaemia
No lid oedema
No angle closure response (or mild if severe)
Usually unilateral
Contact Lens Peripheral Ulcer (CLPU): Symptoms (4)
Lacrimation
Mild foreign body sensation or discomfort (can be painful)
Mild photophobia
Often asymptomatic (50%)
Contact Lens Peripheral Ulcer (CLPU): Management (11)
Temporarily discontinue lens wear until epithelium intact (up to 14 days)
Symptoms should improve on removal of contact lenses (most resolve in 48hours)
Monitor for 24hours - see for follow up next day (return asap if symptoms worsen or do not improve)
Infiltrates can take 2-3 weeks to resolve
Advise against extended wear - cease if reoccurring
Consider refit to daily disposables
Stress importance of hygiene/compliance (stop use of current CL and case - do not throw away until resolves incase used for further investigation)
Manage anterior lid margin disease
Ocular lubricants (preservative free)
Refer to HES if cannot differential from early MK
Scar remains but fades over time
Contact Lens associated Red Eye (CLARE): Aetiology (4)
Occurs following overnight wear
Associated with gram-negative bacterial colonisation of the lens
Or tight lens trapping endotoxins and debris
More common in patients with URTIs
Contact Lens associated Red Eye (CLARE): Signs (5)
Circum-corneal limbal and diffuse bulbar hyperaemia
Diffuse infiltrative keratitis - small focal, diffuse infiltrates
Possible diffuse punctate stain (not overlying infiltrates)
Anterior chamber reaction only if severe
Reduced acuity if infiltrates occur in the central cornea
Contact Lens associated Red Eye (CLARE): Symptoms (4)
Patients usually woken in night with painful eye
Discomfort
Photophobia
Lacrimation
Contact Lens associated Red Eye (CLARE): Management (10)
Temporary cessation on contact lens wear
Resume once infiltrates resolve
Self-limiting on lens removal
Careful monitoring for 24-48 hours to confirm diagnosis
Ocular lubricants to aid comfort
Assess lens fitting
Assess suitability of extended wear
Manage any lid margin disease
Discard lenses and case once resolved
Avoid extended wear if URTI
Infiltrative Keratitis (IK): Aetiology (3)
Anterior stromal infiltrative response (to hypoxia, tight lens, bacterial exotoxins, solution toxicity, lid margin disease, allergic reaction)
Term used to describe non-ulcerative corneal infiltrative events that are not classified as MK/CLARE/CLPU ect
Higher in smokers
Can occur in non-lens wearers
Infiltrative Keratitis (IK): Signs (4)
Bulbar injection/hyperaemia
Focal stromal infiltrates, often at 4 and 8 oclock (if exotoxin related)
Can be unilateral or bilateral (causation dependent)
Patient may have experienced many episodes of red eye previously
Infiltrative Keratitis (IK): Symtoms (5)
Lens intolerance
Discomfort or pain
Photophobia
Lacrimation
Can be asymptomatic
Infiltrative Keratitis (IK): Management (6)
Resolution often up to 14 days (longer if severe)
Manage underlying cause (lens fitting, bacterial bioburden)
Discard lenses and cause once diagnosis confirmed and symptoms resolved
Refit with daily wear or daily disposable if recurring
Change care system if required
Review handling and hygiene
Herpes Simplex Keratitis (HSK): Aetiology (7)
Leading cause of corneal transplants (1 in 10)
Usually caused by HSV1 (90% of population tests seropositives for)
Does not activate in all people (travels along branches to trigeminal nerve)
Can be caused by HSV2
Aggravating factors: UV, fever, extreme cold, systemic or ocular infection
People in poor health, fatigue or immunodeficiency
Likely history of previous attacks
Herpes Simplex Keratitis (HSK): Signs (4)
Epithelial dendritic ulcer
Reduced corneal sensitivity
Can enlarge to from geographic ulcer
Circumcorneal and diffuse bulbar hyperaemia/injection
Herpes Simplex Keratitis (HSK): Symptoms (5)
Usually unilateral but can be bilateral
Severity of pain/discomfort varies with presentation
Burning sensation
Photophobia
Can experience blurred vision
Herpes Simplex Keratitis (HSK): Management (8)
Emergency referral to IP/HES
Sunglasses for photophobia
Preservative free artificial tears for comfort
Keep contact lenses until diagnosis confirmed
Cease lens wear until resolved
Assess lens modality and regime
Refit with daily disposable
Discuss actions to take if reoccurs and continued risk of contact lens wear
Microbial Keratitis (MK) Bacterial/Fungal: Aetiology (3)
Infectious inflammatory event
Caused by gram + and - bacteria (pseudomonas, staphylococcus and streptococcus)
Or fungus (candida, fusarium and aspergillus)
Microbial Keratitis (MK) Bacterial/Fungal: Increased Risks (6)
Contact lens wear - especially overnight wear
Soft daily wear incidence 2-4/100,000 increases to 20/100,000 with overnight wear
Poor case hygiene
Chronic epithelial defect/corneal exposure
Ocular trauma - especially organic material
Lid margin infection
Microbial Keratitis (MK) Bacterial/Fungal: Signs (11)
Corneal lesion - commonly >1mm and usually central
Described as ‘fluffly white’ lesion but can vary
Excavation of epithelium (full thickness loss)
Bowman’s layer and stroma affected
Lid oedema
Epiphora
Diffuse and severe conjunctival hyperaemia
Stromal infiltration beneath lesion
Stromal oedema
Usually unilateral
Satellite lesion common if fungal
Microbial Keratitis (MK) Bacterial/Fungal: Management (5)
Emergency referral to HES or A7E
Cease lens wear
Inform patient to no discard contact lens case and take to HES (for culture)
Sunglasses for photophobia
Reassess suitability for contact lens wear once event has resolved
Microbial Keratitis (MK) Acanthamoeba: Aetiology (6)
Acanthamoeba are protozoans living in water, drains, soil, dust ect
Exits in two forms: motile and formant (cyst form)
Contact lens wearers form the majority of acanthamoeba patients - especially reusable and extended wear
Water contact with lenses
Poor disinfecting
Corneal trauma with soil
Microbial Keratitis (MK) Acanthamoeba: Signs (9)
Epithelial/stromal infiltrates
Pseudodendrites
Radial keratoneuritis
Breakdown of epithelium
Diffuse red eye
Photophobia
Deep inflammation of cornea with ring shape infiltrates
Stromal thinning
Anterior chamber response/hypopyon
Microbial Keratitis (MK) Acanthamoeba: Management (2)
Cease lens wear and keep lenses and case to take to HES
Emergency referral to HES/A&E - phone ahead
Hypoxia (1)
Occurs when there is a reduced oxygen supply to the ocular tissues
Hypercapnia (1)
Accumulation of carbon dioxide
Open Eye Conditions (1)
During this the cornea receives oxygen from atmospheric oxygen dissolved in the tear film
Closed Eye Condition (3)
Receives oxygen via the palpebral conjunctiva
Reduction in availability form 155mmHg to 55mmHg
Average corneal experiences around 3-4% corneal oedema overnight (non contact lens wear)
Effects of insufficient oxygen (7)
Decreased glycolysis
Decreased mitosis
Decreased cell adhesion
Reduced sensitivity
Neovascularisation
Stromal oedema/haze/clouding
Endothelial changes
Hypoxia: Aetiology (7)
Overwear of contact lenses
Low Dk/t contact lenses
Corneal inflammation
Trauma/injury
Immune system disease
Glaucoma/uveitis and similar conditions
Pathophysiological changes to palpebral conjunctiva, tear film and production
Oedema (1)
An increase in the fluid content of tissue
Stromal Oedema (2)
Due to the collagen fibre network of the stroma, the physical dimensions changes from oedema can only be the stroma increasing in thickness
Corneal oedema is expressed as an increase in corneal thickness
Stromal Oedema: Biochemical Theory (6)
Low oxygen
Energy creation due glycolysis is reduced
This reduces energy available for cellular activity
More lactic acid is produced which builds up in stroma
Sufficient osmotic pressure is created which allows water to be drawn into the stroma
this intake is faster than endothelial pump can remove so swelling occurs
Contact Lens Recommendations to Reduce Hypoxia: (2)
Daily wear with a Dk/t of 33 or more
Extended wear with 125 or more (3% swelling)
Oedema: Management (9)
Cease wear until oedema resolves
Cease extended wear
Refit hydrogel to silicon hydrogel
Refit with RGP
Manage dry eye and/or tear film issues
Review wear schedule
Reduce total diameter
Consider edge dynamics
Abandon lens wear id oedema does not resolve
