the anterior eye (keratoconus)

Question 1

what does corneal ectasia mean?

Answer 1

budging and thinning of the cornea due to stromal thinning causing the cornea to become more flexible

keratoconus is progressive non-inflammatory corneal ectasia

Question 2

does keratoconus affect both eyes?

Answer 2

usually, yes but is asymmetric

Question 3

is keratoconus more prevalent in males or females? Whats its inheritance like?

Answer 3

slightly more common in males, has no definite inheritance pattern

Question 4

how does climate affect keratoconus?

Answer 4

more common in hot, dry, dusty, tropical and subtropical climates

Question 5

give 4 possible things that can cause or trigger keratoconus

Answer 5

-atopy: check for the atopic triad which is asthma, eczema and allergic rhinitis as about 1/3 of keratoconus patients have atopy
-inheritance
-eye rubbing/ micro trauma
-connective tissue disorders like downs and marfans

Question 6

give 3 risk factors of keratoconus

Answer 6

-family history
-atopy
-sleep apnea/ floppy eyelid syndrome: these patients already have abnormal collagen as do keratoconus patients.

Question 7

how is keratoconus affected by ethnicity?

Answer 7

4x higher in asian (inida, pakistan bangladesh) compared to Caucasian patients

Question 8

give 3 early (subtle signs) signs of keratoconus

Answer 8

-Patients with lots of changes in their prescription especially in their astigmatism and steepening Ks should make you suspicious of keratoconus
-Scissor and oil drop reflex on ret
-Prominent corneal curves (not just keratoconus patients)

Question 9

give 3 moderate signs of keratoconus

Answer 9

-vogt’s striae = vertical stress lines in descemet’s membrane - by placing pressure on the globe, the lines will disappear
-Fleuscher’s ring = pigmented ring in the peripheral cornea due to iron deposits in the bowman’s layer, can be seen with cobalt blue filter. This is not always keratoconus
-Munson’s sign = v shaped indentation in the lower lid in downwards gaze

Question 10

give 2 advanced signs of keratoconus

Answer 10

-Cornea is extremely thin which you can see in an optic section
-Stromal scarring due to corneal hydrops complication

Question 11

How does corneal hydrops come about?

Answer 11

1. cornea is very thin and stretched
2. rupture in descemet’s membrane
3. causing aqueous to leak into stroma and epithelium
4. causing gross stromal oedema and epithelial oedema - leaves some corneal scarring

hence causes the patient alot of pain and discomfort

Question 12

how does corneal hydrops get treated?

Answer 12

generally resolves by itself in 2-4 momths and can be good as usually causes the cornea to flatten which fixes the keratoconus

Question 13

what is the numerical classification for mild keratoconus? (in terms of Ks)

Answer 13

> 7.50mm

Question 14

what is the numerical classification for moderate keratoconus?

Answer 14

6.50-7.50mm

Question 15

what is the numerical classification for advanced keratoconus? (in terms of Ks)

Answer 15

6.00-6.50mm

Question 16

what is the numerical classification for severe keratoconus? (in terms of Ks)

Answer 16

<6.00mm

Question 17

give three differential diagnoses of keratoconus

Answer 17

-pellucid marginal degeneration
-keratoglobus
-iatrogenic keratectasia

Question 18

what is pellucid marginal degeneration? what are its symptoms?

Answer 18

stromal thinning of the inferior cornea instead of a central cone

Question 19

what are the signs and symptoms of pellucid marginal degeneration?

Answer 19

-Usually asymptomatic until it gets really advanced as it does not affect central cornea so it’s mainly seen with a topographer
-central cornea remains clear
-bilateral
-has large amounts of against the rule astigmatism

Question 20

what is keratoglobus?

Answer 20

diffuse thinning across the whole cornea, congenital and acquired type

Question 21

what is iatrogenic (physical condition as a result of a medical intervention) keratectasia

Answer 21

keratectasia as a result of lasik with undiagnosed keratoconus/ insufficient stromal bed thickness/ irregular topography. Has a similar look to keratoconus

Question 22

What are the surgical and non-surgical management strategies for early keratoconus?

Answer 22

non surgical
-specs
-soft cls

surgical
-collagen cross linking as it helps to halt progression of condition by increasing bonds within collagen in the stroma.

Question 23

What are the surgical and non-surgical management strategies for moderate keratoconus?

Answer 23

non-surgical
-RGPs
-Hybrid lenses

surgical
-intacs implant

Question 24

what are hybrid lenses

Answer 24

Cls with a rigid gas permeable centre surrounded by a soft lens skirt - gives good VA like an RGP but has comfort of a soft CL

Question 25

What are the surgical and non-surgical management strategies for advanced keratoconus?

Answer 25

non-surgical:
-corneo-scleral lenses
-scleral lenses

surgical
-PK/ DALK (penetrating keratoplasty or deep anterior lamellar keratoplasty)

Question 26

What is an intacs implant?

Answer 26

Small rings which try to flatten steepness which reduces distortion to allow a better visual outcome with glasses or CLs

Question 27

what are PK and DALK?

Answer 27

a type of corneal graft - penetrating keratoplasty and deep anterior keratoplasty

Question 28

look up the surgical interventions on youtube and see how theyre done

Answer 28

okay

Question 29

what is the difference between PK and DALK?

Answer 29

PK is a full thickness graft whereas DALK is not a full thickness graft. This means in DALK , there is a much lower risk of graft rejection and heals quicker compared to PK

Question 30

when should you fit Cls to keratoconus patients?

Answer 30

-generally, when VA us <6/9 or Px is symptomatic
-poor spectacle VA

Question 31

what CL can you use for a keratoconus patient who needs RGPs for VA but does not tolerate them?

Answer 31

soft skirt (hybrid lenses)

Question 32

what can you offer in terms of support to patients with keratoconus?

Answer 32

-local eye clinic liaison officer
-keratoconus support groups