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CLO > Corneal Pathologies > Flashcards

Corneal Pathologies Flashcards

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)

A

Blepharitis

Extended wear

Poor case and lens hygiene

24
Q

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

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
Q

Contact Lens Peripheral Ulcer (CLPU): Signs (7)

A

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
Q

Contact Lens Peripheral Ulcer (CLPU): Symptoms (4)

A

Lacrimation

Mild foreign body sensation or discomfort (can be painful)

Mild photophobia

Often asymptomatic (50%)

27
Q

Contact Lens Peripheral Ulcer (CLPU): Management (11)

A

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
Q

Contact Lens associated Red Eye (CLARE): Aetiology (4)

A

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
Q

Contact Lens associated Red Eye (CLARE): Signs (5)

A

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
Q

Contact Lens associated Red Eye (CLARE): Symptoms (4)

A

Patients usually woken in night with painful eye

Discomfort

Photophobia

Lacrimation

31
Q

Contact Lens associated Red Eye (CLARE): Management (10)

A

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
Q

Infiltrative Keratitis (IK): Aetiology (3)

A

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
Q

Infiltrative Keratitis (IK): Signs (4)

A

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
Q

Infiltrative Keratitis (IK): Symtoms (5)

A

Lens intolerance

Discomfort or pain

Photophobia

Lacrimation

Can be asymptomatic

35
Q

Infiltrative Keratitis (IK): Management (6)

A

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
Q

Herpes Simplex Keratitis (HSK): Aetiology (7)

A

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
Q

Herpes Simplex Keratitis (HSK): Signs (4)

A

Epithelial dendritic ulcer

Reduced corneal sensitivity

Can enlarge to from geographic ulcer

Circumcorneal and diffuse bulbar hyperaemia/injection

38
Q

Herpes Simplex Keratitis (HSK): Symptoms (5)

A

Usually unilateral but can be bilateral

Severity of pain/discomfort varies with presentation

Burning sensation

Photophobia

Can experience blurred vision

39
Q

Herpes Simplex Keratitis (HSK): Management (8)

A

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
Q

Microbial Keratitis (MK) Bacterial/Fungal: Aetiology (3)

A

Infectious inflammatory event

Caused by gram + and - bacteria (pseudomonas, staphylococcus and streptococcus)

Or fungus (candida, fusarium and aspergillus)

41
Q

Microbial Keratitis (MK) Bacterial/Fungal: Increased Risks (6)

A

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
Q

Microbial Keratitis (MK) Bacterial/Fungal: Signs (11)

A

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
Q

Microbial Keratitis (MK) Bacterial/Fungal: Management (5)

A

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
Q

Microbial Keratitis (MK) Acanthamoeba: Aetiology (6)

A

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
Q

Microbial Keratitis (MK) Acanthamoeba: Signs (9)

A

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
Q

Microbial Keratitis (MK) Acanthamoeba: Management (2)

A

Cease lens wear and keep lenses and case to take to HES

Emergency referral to HES/A&E - phone ahead

47
Q

Hypoxia (1)

A

Occurs when there is a reduced oxygen supply to the ocular tissues

48
Q

Hypercapnia (1)

A

Accumulation of carbon dioxide

49
Q

Open Eye Conditions (1)

A

During this the cornea receives oxygen from atmospheric oxygen dissolved in the tear film

50
Q

Closed Eye Condition (3)

A

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
Q

Effects of insufficient oxygen (7)

A

Decreased glycolysis

Decreased mitosis

Decreased cell adhesion

Reduced sensitivity

Neovascularisation

Stromal oedema/haze/clouding

Endothelial changes

52
Q

Hypoxia: Aetiology (7)

A

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
Q

Oedema (1)

A

An increase in the fluid content of tissue

54
Q

Stromal Oedema (2)

A

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
Q

Stromal Oedema: Biochemical Theory (6)

A

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
Q

Contact Lens Recommendations to Reduce Hypoxia: (2)

A

Daily wear with a Dk/t of 33 or more

Extended wear with 125 or more (3% swelling)

57
Q

Oedema: Management (9)

A

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

CLO (13 decks)

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