- abreviations:CXL= cross linking
Keratoconus
David Kinshuck
Links
- crosslinking BJO11 BJO16 Moorfields
- PubMed 2012
- Explanation
- UK http://www.keratoconus-group.org.uk/
- inaccurate pressures BJO12
- http://www.nkcf.org/
National Keratoconus Foundation 8733 Beverly Blvd., Suite 201, Los Angeles, CA 90048 United States E-mail your questions or requests for information to: nkcf@csmc.edu. Be sure to include: YOUR NAME AND MAILING ADDRESS. - Word leaflet Keratoconus
- sterile keratitis after crosslinking Eye14
- review..corneal ectasias BJO16
- Other corneal ectasias
- IOP Eye 16
Some notes
www.kcnz.co.nzl
the front curve of the eye is like a rugby ball on its side
Keratoconus topography: in a healthy eye the red area is central, in keratoconus is is off-centre as shown here
Evert lids: papillae are seen.
- S.B Kaye..some notes from his presentation
- explanation ; early diagnosis BJO 14 see
- The condition is linked to allergic eye disease and eye rubbing pathogenesis oxidative stress rubbing eye contributes to keratoconus rubbing and allergic conjunctivitis.
- It is always bilateral. There is irregular astigmatism, that is the front curve of the eye is like a rugby ball on its side. AJO 15
- It starts early teens, but may be diagnosed later.
- First stage of keratoconus is thinning (normal central thickness 550); the corneal layers slip over each other. Cross linking sticks the layers together so they don't slip.
- As the cornea thins it may scar; proud nebulee may develop.
- Environmental and genetic factors Eye 14 . Gene: Znf 469.
- Eye rubbing is a significant risk factor 50%
- Allergic..atopy..risk factor.....makes it progress.
- Much more evident in Asian population...2.5 x and patients present earlier.
- 500 new cases a year in the UK
- It is diagnosed by slit lamp and retinoscopy
- Slit lamp ..look at posterior corneal profile view with a slit demonstrates the condition
- Evert lids: papillae are seen.
- Keratometry can be used to grade 48 normal, 55 severe grade 4 keratoconus: useful for referral.
- Topography demonstrates the problem.
- All young cases progress, until the age of 40y.
- Kmax, kmax-kmin k 2
- Refraction change is a clue the condition is progression.
- Pachymetry, refractive astigmatism.
- Similarly, symptomatic visual loss indicates progression.
- Other signs:change in contact lens wear or comfort, corneal signs, epithelial change, striae.
- Assessing contact lens fit: put hard contact lens look at fit with fluorescein 2% fluorescein.
- Contact lens rubbing will cause progression.
- Confocal epithelium shows changes with rubbing from contact lens, and nerves become visible.
- With a contact lens, if get vascularisation, can cut feeder vessel with syringe.
- Refer for cross linking if progressing.
- May progress >age 30y BJO17
- male,3:1, atopy, south Asian, family 20%
- Cxl: keratoconus, other ectasias, melts,
personal notes 2108
- Post cxl temporary haze,
- after, sometimes it is easier to use cl..refit
- procedure extremely painful
- Serial topography.. treat if worse, moorfields criteria
- Cant cxl if 400 or less
- Dalk.deep anterior lamellar keratoplasty
- Child. general anaeshetic, treat both eyes although explain may be treating unaffected eye
- Pressure..no one knows use disc
- at good hope..Referral scanning drop down KC order set
- Don't wait cxl early
Irregular astigmatism
- The astigmatism is irregular: many of us have irregular astigmatism 1d, but in Keratoconus it may be 8d
- Kmax, kmax-kmin k 2
General
- no eye rubbing
- Lubricants... Chilled
- Optomize surfac
Acute hydrops
- acute hydrops link
- treatment
- hypertonic saline
- lubricants
- cycloplegics if sore, mydrilate 1% twice daily
- antibiotic prophylaxis (if poor ocular surface, lids)
- steroids helpful to reduce haze and neovascularisation
- gas (not initially)
Cross linking CXL
There are surgical treatments for keratoconus, but the new effective treatment is cross-linking. It is not yet approved by NICE for regular use. It should be used early in the condition: it is more effective in stabilising the condition. Explanation.
- Crosslinking: Kmax treat...l < 55d
- serial topography.. treat if worse, 'Moorfield's criteria ' for tretment
- Unlikely to need cxl
- >35y age,
- stable 5y after cxl
- Or good vison
- Cxl..not much happens after 2y
- Mean of 3 measures pentacam
- Epithelium on cxl undecided, utremove mucous layer
- Risk and pain related to epithelium removal
- Cxl keratometry neutral, laser at same time
- Accept may have residual regular astigmatism etc""correct this with glasses
- Ring 2/3 help
- Dalk...best, femtodalk
- Contact lens gap interferes with mapping so can't judge progression..no lens 1 week before topography
- 1 diopter error in early, 4 d in stage 4 disease.
- Keratoconus, other ectasias, melts,
- Post cxl temporary haze, easier to use cl..refit Extremely painful
- Dalk.deep anterior lamellar keratoplasty Cant cxl if 400 or less
- Child. GA treat both eyes although explain may be treating unaffected eye,
- Measuring eye pressure..no one knows how to interpret. Use disc. There are hysteresis corrected IOP charts available.
- At Heartlands: Referral scanning drop down KC order set
Case study: cross linking, CXL (SBK)
- 16y boy
- Reduced vision for 6 months:, 6/36, ...but left 6/9 with refraction, but the refraction has changed a lot over the last 6m. It was much better.
- Patient has asthma, eye rubbing, hey fever, tarsal papillae, striae on inside of cornea, and keratoconic corneal profile
- Start treating the allergic eye
- mast cell stabilisers, lubricants, and Opatanol see
- get atopy controlled with steroids or Cyclosporine first
- ..treat underlying cause..see if the cause of the allergy can be identified, although this is seldom possible
- Baseline orb scans: irregular 4d. Should be 1 d
- this did not stabilise the condition, so he was referred for cross linking.
- Risk: CXL Kills some corneal cells, later recover, if treated properly, must have corneal 380 microns or more. A bandage contact lens is may be used after the procedure, until the epithelium recovers: if painful...have to remove contact lens.
- But SBK now recommends post CXL chloramphenicol ointment with double padding instead a of a bandage contact lens.
Other corneal ectasias
These include... review..corneal ectasias BJO 16
- pellucid marginal degeneration
- patients are older, changes are slower, and often manage the high cylinder with spectacles, even 8d
- keratoglobus: thin peripherally
- and following surgery and refractive surgery (post-lasik ectasia)
Keratoconus management
Keratoconus topography: in a healthy eye the red area is central, in keratoconus is is off-centre as shown here
Evert lids: papillae are seen.
- Identify keratoconus
- identify and treat allergic eye disease
- use topography of a placido disc
- check if cylinder stable; if is changing over 6 months, or there is clear evidence it has changed recently, and the cornea is >400µ thick, cross linking is ideal
- If the cycling/refraction is stable, try contact lenses, Kerasoft lenses
- the cone may be nipple shaped or oval global
- keratoconus may progress <40y
- Usually progress till age 40
- Kerasoft or Rose K contact lenses according to severity
Cross linking procedure
- Remove epithelium ethanol 20%. 30s, wash off,
- Debride
- Ribflavin 10 m, then uv 30m and more riboflavin
- Chloramphenicol
- Bandage cl 1 week
- Nsaid, dex, paracetamol
- Dex qid reducing
- Moxifloxacin postop
- Cornea hazy whilst healing
Contact lenses in keratoconus
- Kerasoft or Rose K contact lenses according to severity
- if patient can only wear lenses for a few hour, consider wear right am, left afternoon,
- Piggy back soft under layers
Corneal graft in keratoconus
- Aim of graft is to enable contact lens use
- Lamellar grafts last longer, lose one line vision
- Penetrating are needed if cone is steep or if deep scarring is present
- treat dry eye , allergies, blepharitis before graft
- Post graft
- Steroids 2 h 1 week, x 4 2m, then slow reduction
- Remove sutures 18 m:remove according to astigmatism ,but good vision leave longer