Diagnosis and management of Keratoconus cases

1. Mohamed ELShafie
Lecturer of ophthalmology
Harvard Medical School Almuni
Director of training unit
Keratoconus

2. Anatomy of
the normal
cornea

3. Collagen

4. •Anterior stroma structure

5. •Posterior stromal structure

6. Keratoconus
Defined:
•Progressive, non-inflammatory thinning disorder of
the cornea, leading to altered shape adversely
affecting visual performance
Variety of ectasias
•Keratoconus
•Pellucid Marginal Degeneration
•Keratoglobus

8. Keratoconus Facts:
•50 to 230 cases per 100,000
•1:200-1800
•Strong association with Atopy
Why ?
••Inflammation, influences elasticity ?
••Eye Rubbing
Definite rationale for:
•Aggressive treatment of Allergic Conjunctivitis
•Mast cell stabilisers
•Steroids

9. •Pathogenesis

12. •Balance of Degradation vs
Regeneration

13. •Asymmetric
•Usual onset during puberty
•Progressive myopia + irregular astigmatism
•Corneal thinning with conical deformation
Association
•Atopy
•eye rubbing
•Down’s syndrome
•Marfan’s syndrome

14. Visual
Symptom
s
 Asymptomatic.
• Blurred vision that does NOT improve with correct
• Frequent change of glasses.
• Photophobia.
• Halos.
• Irritant symptoms (chronic ruber).

15. Diagnosis
Clinical
• Topographic Pentacam – more sensitive and specific
• Belin Ambrosio
Corneal Hysteresis
Newer technology in development
Epithelial mapping

16. •Astigmatism – increasing
•Retinoscopy/ retroillumination:
Droplet appearance – red reflex
Scissoring
•Munson Sign
CLINICAL

17. •Rizzuti’s Sign

18. –
Thinning
–Apical
scarring
–Vogt’s
striae
–
Fleischer
ring

19. •Hydrops

20. •Steep cornea
•Non- orthogonal astigmatism
•Inferior Steepening
•Coinciding point: –Anterior elevation
–Posterior elevation
–Thinnest spot-on cornea
DIAGNOSIS: Corneal Topography

21. Classifications

23. •Slit beam
– Orbscan
•Scheimpflug
–Pentacam (Oculus)
–Gallilei (Zeimar)
–Sirius (CSO)
•OCT
–Casia 2 (Tomey)
–MS 39 (CSO)
–Antereon (Heidelberg)
–Optopol - Revo
3-Dimensional Topography

24. Pentacam(Oculus, Inc)
•Two integrated cameras:
–Central: size and orientation of the pupil, and
fixation
–Rotating Scheimpflug camera
• 50 Scheimpflug images during one scan in less
than 2 seconds
Scheimpflug imaging

26. •High-frequency ultrasound scanning
•Thickness of corneal layers with high
precision.
•Post refractive surgery.
•Not limited to optically transparent tissue.
Ultrasound digital topography

27. Corneal Biomechanics

29. •Spectacles
•Contact lenses: Soft ; toric; RGP
•Corneal graft
•Penetrating keratoplasty
•Lamellar keratoplasty
Treatment options:
TRADITIONAL

31. PERSONALIZED KERATOCONUS
PROGRESSION
1.Steepening of the
anterior corneal
surface.
2.Steepening of the
posterior corneal
surface.
3.Thinning and/or
an increase in rate
of corneal thickness
change from
periphery to
thinnest point.

32. Collagen Crosslinking (CXL)
•Riboflavin
–Large Molecule
–Does not penetrate epithelial tight junctions
•Traditional Method of CXL
–Epithelial Removal
•Transepithelial CXL
–Transepithelial Riboflavin solutions
•Epithelial Disruption CXL
–Alternative option
–Breaks in epithelium allow Riboflavin to penetrate

33. Collagen Cross
Linking
Natural:
–Ageing
Pathogenic:
–Diabetes Mellitus –chronic hyperglycaemia
Artificial:
–Strengthen collagenous valves: Cardiac
Surgery
–Cornea for Keratoconus !

34. –Riboflavin
–UVA light exposure
–Formation of free radicals
–Oxidation reaction with development of cross-
links in collagen
Mechanism

35. Increases Tensile rigidity in Human Cornea by 328% (stress testing)

37. Epithelial
Disruption
•Topical Anesthesia
•Topical Antibiotic
•Topical Pilocarpine(2%)
•Epithelial Disruption (Daya Disruptor)
•Riboflavin instillation (45 mins)
•Check penetration at Slit Lamp
•Bandage Lens

38. •UV light exposure (370 nm)
•3 mW/cm2
•Variable aperture
•30 minutes

39. RESULTS :
Different
Bandage CTL:
removed by
48 hours
Persistent
Epithelial
Defect
Infectious
Keratitis
Sterile
Infiltrates
Pain – day of
procedure
Demarcation
line
or
Anterior Haze

40. CXL – 1 month postop Demarcation

41. •Corneal thickness must be 400μm
•If thinner use riboflavin without
dextran
•Measure before treatment!
•Irradiance is reduced by 95% at
endothelium
Safety

42. ACELERATED
CXL
More power = less time
18 Mv/cm2 = 5 mints
9 Mv/cm2 = 10 mints
3 Mv/cm2 = 30 mints

43. Intracorn
eal Rings

44. Function
of
Diameter
and
Thickness

45. Insertion
techniques
•Conventional:
manual lamellar
tunnel creation;
fixed diameter
•Femtosecond
laser: quicker,
easier,
customizable
channel
parameters

46. –5.0/6.0mm PMMA micro-inserts
–600/800 microns wide
– triangular cross section
–160 (90-210) degree segments
- 0.15mm to 0.35mm
–First implanted 1994
Ferrara rings:

47. Indications
•Spectacle / contact lens intolerance
•Keratometry up to 62D
•Clear visual axis
•Pachymetry > 400 microns

49. complications
•Infection
•Extrusion
•Perforation - mechanical > femto
•Channel deposits
•Inadequate effect

50. Corneal Allografts to Reshape the Cornea

51. •Consider the cone
•Space filling/ reinforcing
•Flattening effect
•Concentrate on area of depression

52. 1 month Postop

53. •Endothelium is normal
•Anterior Lamellar Keratoplasty (ALK) preferable
Advantages
–Retains endothelium
–Reduces risk of corneal blindness
Disadvantages (previously)
–Poor Vision
•Interface opacification
•Regular and Irregular Astigmatism
–Technical skill
•Perforation
Corneal Grafts for Keratoconus:

54. •Expulsive Choroidal Haemorrhage
•Rejection & Failure
•Reduced survival of Regrafts
•Glaucoma
•Cataract
•Endophthalmitis
PK – Hazards…

55. •Descemet’s
–Big Bubble
–Viscodissection
•Femtosecond Assisted
DALK – How ?

59. Poll Question
pathoanatomical findings in keratoconus?
1)Epithelial thinning + Degeneration and/or rupture in Bowman's
layer + Stromal thinning.
2)Endothelial cell loss and stromal thinning.
3)Epithelial thinning + Activation of keratocytes