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Corneal Pathologies Flashcards

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1
Q

Microcysts: Aetiology (6)

A

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

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2
Q

Microcysts: Signs (6)

A

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

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3
Q

Microcysts: Symtpoms (3)

A

Usually none

If severe, may see mild haze

Lens intolerance if severe

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4
Q

Microcysts: Grading (5)

A

0: none

1: 1-10

2: 11-30

3: 31-70

4: >70 cysts

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5
Q

Microcysts: Management (8)

A

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

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6
Q

Microcysts vs Vacuoles (3)

A

Vacuoles are spherical, fluid-filled cysts

Vacuoles display unreversed illumination

Microcysts display reversed illumination (due to density)

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7
Q

Striae: Aetiology (6)

A

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

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8
Q

Striae: Signs (4)

A

Fine white vertical lines

Seen posterior in stroma

Number increases with increase of oedema

Becomes ‘greyer’ and thicker as oedema increases

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9
Q

Striae: Symptoms (1)

A

None

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10
Q

Folds: Aetiology (5)

A

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

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11
Q

Folds: Signs (2)

A

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

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12
Q

Dellen: Signs (4)

A

Saucer like depression in peripheral cornea

Possible overlying stain

Epithelium intact

Localised neovascularisation and scarring (depends on cause)

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13
Q

Dellen: Symptoms (2)

A

Usually none

Symptoms linked to causation (dryness or discomfort)

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14
Q

Dellen: Management (4)

A

Cease lens wear

Usually resolves quickly

Manage any epithelial defect

Resolve causation

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15
Q

Ulcer (1)

A

Local defect, or excavation of the surface tissue which is produced by sloughing of inflammatory necrotic tissue

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16
Q

Infiltrates (1)

A

Single or multiple discrete aggregates of grey/white inflammatory cells that have migrated to the corneal tissue

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17
Q

Microbial (1)

A

Used to refer to an event that us ‘culture positive’ (infective in nature)

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18
Q

Supprative (1)

A

Used when pus is present (purulent exudate)

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19
Q

Epithelial Break/Defect (1)

A

Areas of epithelial damage, due to mechanical trauma, desiccation, infection ect

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20
Q

Peripheral (1)

A

Corneal infiltrative events that occur outside the central 6mm of the cornea

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21
Q

Sterile (1)

A

Used to refer to corneal infiltrative events where there is no microbial infection within the corneal tissue

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22
Q

Contact Lens Peripheral Ulcer (CLPU): Other names (3)

A

Sterile infiltrates

Sterile keratitis

Sterile corneal ulcer

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23
Q

Contact Lens Peripheral Ulcer (CLPU): Increased Risk (3)

Study These Flashcards
A

Blepharitis

Extended wear

Poor case and lens hygiene

24
Q

Contact Lens Peripheral Ulcer (CLPU): Aetiology (3)

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A

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

25
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
26
Contact Lens Peripheral Ulcer (CLPU): Symptoms (4)
Lacrimation Mild foreign body sensation or discomfort (can be painful) Mild photophobia Often asymptomatic (50%)
27
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
28
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
29
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
30
Contact Lens associated Red Eye (CLARE): Symptoms (4)
Patients usually woken in night with painful eye Discomfort Photophobia Lacrimation
31
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
32
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
33
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
34
Infiltrative Keratitis (IK): Symtoms (5)
Lens intolerance Discomfort or pain Photophobia Lacrimation Can be asymptomatic
35
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
36
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
37
Herpes Simplex Keratitis (HSK): Signs (4)
Epithelial dendritic ulcer Reduced corneal sensitivity Can enlarge to from geographic ulcer Circumcorneal and diffuse bulbar hyperaemia/injection
38
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
39
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
40
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)
41
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
42
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
43
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
44
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
45
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
46
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
47
Hypoxia (1)
Occurs when there is a reduced oxygen supply to the ocular tissues
48
Hypercapnia (1)
Accumulation of carbon dioxide
49
Open Eye Conditions (1)
During this the cornea receives oxygen from atmospheric oxygen dissolved in the tear film
50
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)
51
Effects of insufficient oxygen (7)
Decreased glycolysis Decreased mitosis Decreased cell adhesion Reduced sensitivity Neovascularisation Stromal oedema/haze/clouding Endothelial changes
52
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
53
Oedema (1)
An increase in the fluid content of tissue
54
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
55
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
56
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)
57
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

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