Corneal - Ectasia - presentation 1 .pptx

Corneal Ectasia
by Dr. Eman Alshebli
Supervised by Dr. Khaled Ayesh

Definition of Corneal Ectasia
Ectasia is the dilatation or expansion or distension.
Corneal ectasia refers to the progressive thinning and distortion of
the cornea, leading to a protrusion and visual impairment.

Causes of Corneal Ectasia
1 Keratoconus
Keratoconus, a common cause of
corneal ectasia, involves the cornea
gradually thinning and developing a
cone-like shape. Factors such as
genetics, eye rubbing, and allergies
may contribute to its development.
2 Pellucid Marginal
Degeneration
Pellucid marginal degeneration
leads to bilateral thinning of the
inferior peripheral cornea. Its cause
is unknown, but it may be associated
with genetics and eye trauma.
3 Keratoglobus
Keratoglobus is a rare condition characterized by a generalized thinning and globular
protrusion of the cornea. This condition is thought to have a genetic basis.

Symptoms and Diagnosis
1 Visual Distortion
2
Frequent Changes in
Eyeglass Prescription
3 Corneal Topography

Irregular conical shape of cornea, progressive disease,
secondary to stromal thinning, protrusion, and irregular
astigmatism.
• Onset: puberty
• Non inflammatory
• 50% of normal fellow eyes will progress to KC within
16 years, greatest risk at 6 years of onset
• Both eyes are affected eventually
• Develops asymmetrical.
• Variable rate of progression

Etiology:
• Role of heredity is not clearly defined,
most are without +ve family history,
only 10%- AD transmission.
• Association with systemic conditions:
 Down syndrome, Turner syn,
Ehlers danlos syn, Marfan
syndrome.
 Atopy, osteogenesis imperfecta,
mitral valve prolapse and mental
retardation.

• Ocular associations:
VKC, blue sclera, aniridia, ectopia lentis, leber congenital
amaurosis, RP, Eye rubbing.
• Hormonal changes:
Proteases, protease inhibitors
• Rigid contact lens wear.

Presentation:
• During puberty it's unilateral, due to progressive
myopia and astigmatism which subsequently
becomes irregular.
• Due to asymmetrical nature, the fellow eye is usually
normal with negligible astigmatism at presentation.
• Occasionally, initial presentation is with acute
hydrops.
Risk factors:
• Eye rubbing associated with atopy
• Sleep apnea
• Floppy eyelid syndrome

Symptoms:
• Blurry vision
• Frequent change in eye glass
prescription
• " Squinting" in order to see better
• Change in the astigmatic correction
in the range of 16-25 year-old.
• Distortion rather than blur at both
distance and near vision
• Double vision
• Ghost images

Signs:
1.Irregular astigmatism :
Keratometry shows irregular astigmatism, where the principal meridians
are no longer go degree apart and the mires cannot be superimposed.

2. Oil droplet sign:
On direct
ophthalmoscopy from a
distance of half a meter

3. Scissoring reflex
on Retinoscopy
:

4. On slit lamp biomicroscopy:
Deep stromal stress lines
generally vertical, but they can
be oblique also disappear with
pressure on the globe.

5. sub-epithelial scarring
Ruptures in Bowman's
membrane.
Thickening of the corneal
nerves makes them more
visible.

6. Fleischer ring:
Yellow brown ring of pigment,
due to deposition of
hemosiderin in the epithelium,
Which may or may not
completely surround the base
of the cone
Visualized best with cobalt blue
filter.

7. Munson sign:
Bulging of lower lid
in down gaze

8. Corneal thinning:
Significant corneal
thinning, up to 1/5th of
corneal thickness can
be seen in the
advanced stages.

Descemet's membrane rupture leads to aqueous flow
into the cornea.
Symptoms are: Sudden decrease of vision, pain, and
photophobia
Heals within 6-10 weeks and the corneal edema clears
leading to variable amount of stromal scarring.
9. Acute hydrops:

Treatment of acute hydrops:
• For initial stages of acute episodes:
Cycloplegia
Hypertonic(5%) saline ointment
Patching
Soft bandage contact lens
• Intracameral gas injection in the
acute stage may accelerate resolution
• Healing (scarring and flattening of
cornea) results in improved VA.

10. Corneal topography:
shows irregular astigmatism
and is most sensitive method
to detect early keratoconus
and for monitoring
progression.
11. Keratometry reading are
steep.

Classification:
It can be graded by the highest
axis of corneal power on
keratometry as:
• Mild <48D
• Moderate 48-54D
• Severe >54D

• Central K2
 Normal <47.2D
 Keratoconus >48.7D
• Inferior-superior asymmetry index :
>1.2D
• Astigmatism: >2.5D
• Pentacam posterior elevation
 Normal ≤+17µm
 Suspicious +18µm to +20µm
 Risky >+20µm
• Pentacam anterior elevation
 Normal ≤+12µm
 Suspicious +13µm to +15µm
 Risky >+15µm
Cutoff points for keratoconus

Management:
Investigations:
 Corneal topography
• Keratometer
• Keratoscope
• Photokeratoscope
• Videokeratography: by using:
 Placido based system
 Elevation based system: Uses different method:
 Optical slit scan
 Side band interferometry
 Restersterography or resterphotogrammetry
• Or B-scan topography System in one of popular equipment in
this elevation based system which uses slit scan technology.

 Corneal thickness measurement and
examination:
• Pachymetry
• Pentacam
• Optical coherence tomography
• Ultrasound biomicroscopy
• Slit lamp examination

Treatment:
• Spectacles: In early cases.
• Contact lenses: No one lens is best suited for
every type of keratoconus.
1. Soft contact lenses
2. Rigid gas permeable lenses (RGP)
3. Special contact lenses:
 RoseK lenses
 Piggy back lenses
 Hybrid lenses
 Scleral lenses

• Epi-keratoplasty:
Patients without corneal scarring.
• Keratoplasty:
Penetrating or DALK in patients with
advanced disease, especially with
significant corneal scarring.
• Optical outcomes are poor

• Intra-corneal ring segments (intacs)

• Corneal collagen cross-linking
• Corneal transplant

Pellucid marginal degeneration
Peripheral corneal thinning disorder in a crescentic
manner, typically involving inferior cornea.

Presentation:
• Bilateral
• Asymmetrical
• Non-inflammatory
• Perfectly transparent
• Non-vascularized
• Rare, progressive
• Considerably underestimated often
misdiagnosed as keratoconus.
• Equal gender distribution
• Age 20-40yrs at the time of clinical
presentation
• Occasionally it may co-exist with
keratoconus and keratoglobus.

• Etiology:
 Idiopathic
• Presentation:
 4th-5th decades
 Uncorrected visual acuity is often severely reduced
 Progressive deterioration in uncorrected and spectacle
corrected visual acuity
 Refraction and keratometry show against-the-rule
astigmatism.

• Signs:
 Bilateral, slowly progressive crescentic (1-2mm) band of inferior corneal
thinning.
 Extending from 4-8 o'clock between limbus and1-2 mm of normal cornea
between the limbus and the area of thinning.
 Acute hydrops are less compared to keratoconus
 Corneal ectasia is most marked just central to the band of thinning
 The central cornea is usually of normal thickness
 The degree of thinning is usually severe, resulting in upto 80% stromal tissue
loss.
 The corneal protrusion is more marked- superior to the area of thinning.
 Corneal topography shows butterfly pattern, with severe astigmatism and
diffuse steepening of the inferior cornea.

• Differential diagnosis:
 Peripheral corneal melting disorders (eg,
Mooren Ulcer)
 Contact lens-induced warpage
 Keratoglobus
 Terrien marginal degeneration.

Treatment:
• Spectacles:
 Fail early due to increase in irregular astigmatism.
 Contact lenses:
 Early- soft toric
 Advanced cases: RGP’s
• Surgical options:
 Large eccentric penetrating keratoplasty
 Crescentic lamellar keratoplasty
 Wedge resection of diseased tissue
 Epikeratoplasty
 Intra corneal ring implantation (Intacs)

Extremely rare
Non progressive or minimally
progressive
• Etiology:
 Congenital
 genetically related to keratoconus
• Associations:
 Leber congenital amaurosis
 Blue sclera
• Onset:
 At birth
• Signs:
 In contrast to keratoconus cornea
develops globular rather than
conical ectasia.

• Corneal thinning is generalized.
• Cornea is usually transparent.
• Corneal diameter is normal.
• Acute hydrops are less compared to
pellucid marginal degeneration and
keratoconus.
• Cornea is more prone to rupture on
relatively mild trauma.
• Corneal topography:-Shows generalized
steepening

• Differential diagnosis:
 Congenital glaucoma
(Edematous cornea)
 Megalo-cornea (Not thinned)
• Treatment:
 Scleral CL’s
 Surgical results are poor,
though large diameter grafting
can be attempted

Posterior Keratoconus
• Unilateral thinning of the posterior cornea.
• Least common of all ectasias
• Developmental, usually non-progressive.
• Mild to moderate decrease in visual acuity
• Less astigmatism as compared to anterior keratoconus
Treatment:
 No treatment if abnormality is outside visual axis
 Glasses can correct refractive error
 Penetrating keratoplasty can be considered in patients
with poor vision.

Ectasia cicatrix (Keratectasia):
• There is marked thinning at the site of ulcer.
• It bulges forwards even in presence of normal IOP.
• There is no adhesion of iris to cornea.
• The cicatrix may become consolidated and flatter later on.

Post-refractive surgery ectasia
It is a loss of corneal integrity leading to corneal
warpage that often resembles keratoconus.
It is more likely to occur following LASIK, radial
keratotomy (RK), or astigmatic keratotomy (AK)
surgery.
These types of refractive surgeries are more likely to
cause ectasia because of how they disrupt the
cornea.

Risk factors for ectasia after LASIK or PRK are:
 young age,
 high myopia,
 thin residual stromal bed,
 thin preoperative cornea,
 and abnormal preoperative contour.
 KCN or forme fruste KCN
Ectatic changes can occur as early as 1 week after LASIK, or
they can be delayed up to several years after the initial
procedure.
In many cases, corneal transplant is eventually performed to
manage this complication.

• Major Risk factors
• Abnormal topography:
 Keratoconus
 Forme fruste keratoconus
 Pellucid marginal degeneration
• Residual stromal bed thickness:
 Most surgeons consider 250 or 300 microns
as the minimum
 Note: many eyes do fine below these levels
and eyes have developed ectasia above
these levels
 Measure the stromal bed after the flap is cut

• Minor risk factors:
 Younger patients.
 Asymmetry
 Enhancements
 Myopia
• Treatment is the same as keratoconus
 Rigid contact lenses
 Intacs
 Keratoplasty: DALK or PKP
 Collagen cross-linking

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