it covers keratoconus, glubus. PMK, post keratoconus

1. CORNEAL ECTASIAS

2. CORNEAL ECTASIAS
• It is a group of diseases affecting the corneal
shape due to CORNEAL THINNING.
– Anterior Keratoconus
– Keratoglobus
– Pellucid Marginal Degeneration
– Posterior Keratoconus
• Key Features:
– Usually Bilateral, often asymmetrical
– Isolated to cornea
– Non inflammatory

3. KERATOCONUS
• Progressive corneal steepening, typically inferior
to the centre of the cornea.
• Non inflammatory, usually bilateral.
• Incidence: Between 50 and 230 per 100 0001.
• Unilateral involvement is 2–4%2.
• Onset starts at the age of puberty.
1. Krachmer JH, Feder RS, Belin MW. Keratoconus and related noninflammatory corneal thinning disorders. Surv Ophthalmol. 1984;28:293–322.
2. Holland DR, Maeda N, Hannush SB, et al. Unilateral keratoconus. Incidence and quantitative topographic analysis.
Ophthalmology.1997;104:1409–1413.

4. ASSOCIATED DISEASES
Systemic
 Atopic Diseases (35%)1.
 Down’s Syndrome (5.5-15%)2.
 Ehler-Danlos and osteogenesis imperfecta.
 Mitral valve prolapse.
 Marfan Syndrome.
 Ocular
 Vernal Conjunctivitis.
 Retinitis Pigmentosa.
 Leber’s congenital amaurosis
 Retinopathy of prematurity.
 Fuchs’ Dystrophy.
1. Rahi A, Davies P, Ruben M, et al. Keratoconus and coexisting atopic disease. Br J Ophthalmol. 1977;61:761–764.
2. Cullen JF, Butler HG. Mongolism (Down’s syndrome) and keratoconus. Br J Ophthalmol. 1963;47:321–330.

5. ETIOLOGY
BIOCHEMICAL:
• Up-regulation of degradative enzymes (acid
esterase and acid phosphatase, cathepsins B and
G, and some matrix metalloproteinases) and the
down-regulation of proteinase inhibitors.
• There is a four fold increase in the receptors of
INTERLEUKIN 1 causing apoptosis of stromal
keratocytes.
• Microtrauma Release of IL-1 from epithelial
epithelium.

6. HEREDITY
• Autosomal dominant with incomplete penetrance.
• Frequency of inheritance is 6%.
• Keratoconus prevalence in first-degree relatives to be
3.34%, about 68 times that found in the general
population.
PATHOLOGY
• Keratoconus can involve every layer and tissue of
cornea.
• Superficial cell enlargement and prominence of
elongated cells in the corneal epithelium.

7. Early degeneration of basal epithelial cells.
Disruption of epithelial basement membrane.
Epithelium grows posteriorly into the Bowman’s Layer,
with collagen growing anteriorly into the epithelium.
Z shaped interruptions at the level of the basement
membrane.
Fragmentation of the Bowman’s layer. (Early change)

8. Fleischer ring found at the base of the cone is a
hallmark of keratoconus.
Breaks in Bowman’s layer fill with scar tissue.
Fine scars consolidate leading to formation of reticular
branched opacities at this level.
Collagen lamellae are released from their interlamellar
attachments or from their attachments to Bowman’s
layer and become free to slide Thinning without
collagenolysis.

9. Alteration of the normal orthogonal arrangement of
the collagen fibrils leads to stromal tissue
instability.
Most common location for the apex of the cone, in
the central or inferior cornea, isrelated to this.
Endothelial cell pleomorphism and polymegathism

10. DIAGNOSIS
• Onset of the disease is at puberty.
• Usually appears in the 2nd or 3rd decade.
SYMPTOMS:
• Progressive visual blurring & disortion due to
irregular astigmatism.
• Frequent change of glasses.
• Pain, photophobia.
• Eye rubbing.

11. Scissoring of red reflex on
retinoscopy
One of the earliest signs
SIGNS:

12. Munson Sign
Buldging of
the lower
eye lid in
downward
gaze.

13. Papillae, trantas dots, limbal nodule, pigmentation, ropy
discharge.

14. Corneal thinning, scarring.

15. Corneal ectasia:
Apex is inferior to the
horizontal line to the
pupillary axis. Corneal
thinning of about 1/2-1/5 is
observed at the apex.
2 types of cones:
Round/ Nipple shaped
Oval shaped

16. Fleischer Ring
Iron depositions in the
corneal epithelium.
The ring configuration is
due to irregular
distribution of tears at
the base of the cone and
resultant deposition.

17. Vogt’s Striae
Fine vertical lines
formed due to
compression of
descemet’s
membrane.
Parallel to the
axis of the cone

18. Prominent corneal
nerves

19. Rizzuti
phenomenon

20. • Breaks in Descemet Membrane
• Stromal edema

21. Charleux Sign
Dark reflex in the area of
the cone on observation
of the cornea with pupil
dilated using a direct
ophthalmoscope set on
plano.

22. DIFFERENTIAL DIAGNOSIS
• Pellucid marginal degeneration.
• Keratoglobus.
• Post traumatic corneal ectasia.
• Protrusion of cornea subsequent of corneal
thinning from ulceration.
• Corneal ectasia following keratorefractive
surgery.

23. CLASSIFICATION

24. AMSLER KRUMEICH CLASSIFICATION

25. INVESTIGATIONS
• KERATOMETRY:
Mires are commonly steep, highly astigmatic, often
egg shaped.
Inability to superimpose the central keratometric
rings is due to irregular astigmatism. (hallmark)
LIMITATIONS:
Provides information only of the central 3mm of
cornea.
Not useful in irregular astigmatism.

26. • VIDEOKERATOMETRY
Based on Placoid disc principle.
Early disease: Isolated area of smaller ring spacing
and distortion.
Advanced disease: Decrease in overall ring spacing
and becomes increasingly irregular
LIMITATIONS:
Does not give accurate information about the
posterior curvature and corneal thickness.
Cannot detect early keratoconus.

27. Astigmatism progression:
Symmetric Bow tie pattern
Asymmetric appearance
Inferotemporally displaced steep sided cone

28. • ORBSCAN
Uses the principle of scanning slit combined with a
Placoid system.
Provides reliable information about the anterior and
posterior elevation and best fit sphere and a
corneal pachymetry map.
LIMITATIONS
The posterior curvature map might not be 100%
accurate.
Requires patient fixation for accurate data.
Data pertaining to the central cornea is not
accurate.

30. • PENTACAM
USES a rotating Scheimpflug camera.
Provides reliable data of anterior and posterior
corneal elevation and accurate measurement of
corneal thickness.
The images taken by a pentacam maintain the
central point of each meridian hence the software
can re register these central points and eliminate
the eye movement.
Data is 10 times more accurate than the that
obtained from Orbscan.

33. • PACHYMETRY
Ultrasonic and optical based devices can be used.
Measurement of corneal thickness is useful for
diagnosis, documenting progression, and planning
treatment.
• OCULAR RESPONSE ANALYSER
Helps in making a diagnosis and classifying by
assessing corneal hysteresis and resistance.

35. TREATMENT
• NON SURGICAL
– Spectacles: Only in early cases.
• Once irregular astigmatism develops this type of visual
correction cannot be used.
– Contact lens: Soft toric lenses, standard bicurved
hard lenses, custom back toric lenses, piggyback
systems, hybrid lens, scleral and mini scleral lens.

36. RIGID GAS PERMEABLE LENS
• First choice in correcting irregular astigmatism.
• Fitting strategies:
Apical clearance: There is no touch in the apical area.
Advantage: 1. Reduced risk of scarring
2. Whorled keratopathy
3. Corenal erosion
Limitation: Hampers tear exchange, edge can come in
visual axis.
Rarely used now days.

37. Apical touch : Aims at providing primary lens support at
the apex of the cornea.
The central optic zone of the lens touches the central
cornea.
ADVANTAGE: Better quality of vision
LIMITATION: Corneal scarring and intolerance over
long term use.
 Three point touch: Most popular technique
The lens bearing is shared between apex and mid
peripheral cornea. Minimizes apical scarring, better
comfort and longer wearing time.

38. PIGGYBACK LENS SYSTEM
• Consists of the fitting a rigid gas permeable on
top of a soft contact lens.
• The soft lens is used to improve wearing
comfort and provide a more regular area for
the gas permeable contact lens to sit.
• The gas permeable contact lens is used for
providing adequate visual acuity.

40. HYBRID CONTACT LENS
• Contain a rigid gas permeable center with a
soft skirt.
• They are fitted with no or minimal apical
touch in the central cornea.
ADVANTAGE: Can be fit on cones of any severity.
LIMITATION: Can cause hypoxia related changes
like vascularisation and central corneal
clouding.

42. ROSE K LENSES
• Multicurve lenses with small optical zone
which fits snugly over the cone.
• Rose K contact lens provides greater comfort,
better quality of vision and requires lesser
chair time.
• Rose K2 IC is a larger diameter, intralimbal lens
that can be used for oval cones.

43. SCLERAL LENSES
• They rest on the sclera without touching the
cornea or the limbus leaving a clear area
between the contact lens and the cornea.
• They are of two types:
– Prosthetic Replacement Of the ocular Surface
Ecosystem (PROSE)
– Boston Ocular Surface Prosthesis (BOSP)

44. ADVANTAGE
Good centration, stability and improved Visual
acuity.
Extermely useful in patients with advanced
ectasias who are intolerant to contact lenses
or when immediate surgery is not possible
LIMITATION
High cost, reduced tear exchange and difficult
insertion and removal.

45. • SURGICAL MANAGEMENT
– INTRACORNEAL RING SEGMENT INSERTS
– CORNEAL CROSS LINKAGE
– LENTICULAR REFRACTIVE SURGERY
– CORNEAL TRANSPLANT

46. INTRACORNEAL RING SEGMENT INSERTS
• Ferrara rings:
Fixed inner diameter of 5.00 mm with a triangular
anterior contour.
• Intacs:
Inner diameter of 6.8 mm and a flat anterior contour.
Hexagonal in cross section.
Intacs SK: Inner diameter of 6.00 mm and elliptical cross
section.
The ring segments should be inserted upto 2/3rd depth of
the cornea.
Minimum corneal thickness should be 450 µ.
They do not prevent the progression of the disease.

47. The technique involves
the implantation of
one of two
polymethy metha
acrylate segments in
the stroma to flatten
the central cornea.
Intralamellar pockets
are created with the
help of a vaccum
lamellar dissector or
femtosecond laser.

48. CORNEAL COLLAGEN CROSSLINKING
• The most recent addition to surgical management.
• It may slow or halt the progression with photo-
oxidative treatment to increase the rigidity of the
corneal stroma.
• 60-70% patients show some stabilization following
this treatment.
• The therapeutic effects are limited upto 300 µ of the
anterior stroma.
• This technique should not be performed for corneas
less than 400µ in thickness.
• It carries a slight risk of development of keratitis.

49. STEPS:
Under topical anaesthesia 6-7 mm of central corneal
epithelium is removed.
Riboflavin 0.1% solution is applied topically (10-30
mins) and cornea is irradiated with UVA light of 370 nm
for 30 mins.
Production of reactive oxygen species helps create
covalent bonds between collagen fibrils.

52. CORNEAL TRANSPLANTATION
Penetrating Keratoplasty:
Success rate in 90-95%.
Visual recovery takes
several weeks to months.
Full stabilisation might
even take a year.
Hydrops that does not
clear by 3-4 months is
best treated by
Penetrating keratoplasty.

53. DEEP ANTERIOR LAMELLAR
KERATOPLASTY
• It is the procedure of choice as there is good
endothelial count even after hydrops.
• Advantages over Penetrating keratoplasty:
Reduced risk of Rejection
Reduced risk of Endopthalmitis
Greater wound stability
Reduced need for topical steroids Faster healing

54. LAYER BY LAYER MANUAL DISSECTION
Partial trephination of variable depth ranging from
50-70% of corneal thickness, stroma is removed with
the help of a crescent.
Layer by layer removal of the stroma to reach as
close to the Descemet’s membrane.
LIMITATION:
Poor visual outcome due to residual stroma and
interface haze.

55. AIR ASSISTED DALK
Archila first described this technique involving air
injection to achieve dissection as close to DM as
possible.
The Big bubble technique was described by Anwar
and Teichmann and is the most widely used
technique.
Steps:
Air injection into the stroma through a groove created by
trephining 60-80% of the stromal thickness.
Air infiltrates the potential space between deep stroma
and DM and creates a Dome shaped detachment of DM.
Once the plane of separation is created the stroma can be
easily excised.

56. FEMTO LASER ASSISTED DALK
It can be used to create corneal incisions with
customised graft edges and lamellar planes for both
donor and recipient corneas.
ADVANTAGE:
Accuracy of forming the bubble at desired
corneal depth
Positive refractive outcome
LIMITATIONS:
Cost and availability

57. KERATOGLOBUS
• Bilateral ectatic disorder which is non
progressive or minimally progressive.
• Generalised thinning with marked peripheral
thinning.
• Types:
– Congeital: Ehler’s-Danlos type IV and brittle
cornea syndrome.
– Acquired: Initially keratoconus keratoglobus.

59. Clinical Features
Blurring of vision.
Corneal perforation spontaneous or following
minimal trauma.
Rarely might present as photohobia, glare, pain,
conjunctival injection following acute hydrops.
Limbus- limbus corneal thinning
Blue sclera due to thinning

60. Differential Diagnosis
Keratoconus
Pellucid Marginal Degeneration
Megalocornea
Congenital glaucoma

61. Investigations
Diagnosis is essentially clinical.
Ultrasonic Pachymetry shows reducude corneal
thinckness.
Corneal Topography shows generalised thinning and
irregular astigmatism is difficult to perform in
advaced cases .

62. Management
Conservative:
Observation is the rule in early cases.
Patient is advised to use polycarbonate glasses.
Visual rehab is done using refractive correction
for high myopia.
Scleral lens, rigid gas permeable lens, reverse
geometry hydrogel lens, large diameter inverse
geometry rigid gas permeable lenses can be
used.

63. Surgical Management
It is difficult to manage these patients by surgery:
Large sized grafts are required increasing the risk
of rejection.
Peripheral sutures often cut through.
Proximity of the graft to the limbus increases risk
of rejection.
Higher chances of perforation.

64. PELLUCID MARGINAL DEGENERATION
• Bilateral corneal ectatic
disorder.
• Band of thinning 1-2mm
in diameter extending
from 4 to 8 o’clock.
• Area of thinning is
separated from the
limbus by 1-2mm of
normal cornea.
• Onset: 2nd- 5th decade of
life.
Beer Belly
appearance

65. • Blurring of vision due to against the rule
astigmatism.
• Frequent chances of glasses.
• Ocular examination reveals thinning of inferior
cornea with 1-2 mm separation from the
limbus.
• Ectasia is just superior to the thinning.
• Protruding cornea is of normal thickness.
• Occasional concentric Descemet folds seen
inferiorly.

66. Investigations
• Corneal topography:
Inferior peripheral steepening
extending into the mid
periphery.
Crab- claw appearance.
Against the rule: Superiorly.
With the rule: Inferiorly.

67. Management
• Spectacles in early cases.
• PROSE, BOSP and hybrid contact lens can be
used.
• Large diameter Penetrating keratoplasty.
• Combined Lamellar with penetrating
keratoplasty.
• Crescentric lamellar keratoplasty.
• Crescentric or wedge excision if ectasia in
small sector.

68. POSTERIOR KERATOCONUS
• It is a congenital corneal anomaly
in which the posterior corneal
surface protrudes into the stroma.
• Sporadic, unilateral, non
progressive.
• Variant of corneal mesenchymal
dysgenesis.
• Scarring is seen anterior to the
descemet bulge.
• Pathologic Examination: Scarring
at Bowman’s membrane and
thinning of descmet membrane
with excrescences.