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Secondary Corneal Ectasia.pptx
1. Secondary Ectasia..
How to interpret?
Subtitle
By
Dr. Amr Mounir, MD, PhD
Assistant Professor of Ophthalmology,
Sohag University .. Egypt
2. As we know…
- Laser corneal refractive surgery
became a very frequent
surgery..
So, It is important to differentiate
and diagnose varieties of normal and
abnormal Pentacam cases
4. Corneal ectasia
Definition:
Ectatic corneal disease (ECD) comprises a group of
disorders characterized by progressive thinning and
protrusion of the cornea, leading to visual impairment.
5. Types of corneal ectasia
- Primary:
Characterized by intrinsic structural abnormalities in the
cornea. e.g.; Keratoconus
- Secondary:
Corneal shape changes caused by external factors.
6. Causes of secondary ectasia
1- Post Lasik Ectasia
2- Post Penetrating Keratoplasty Ectasia
3- Scar related ectasia
8. But First, We should know the normal
Postlasik Pentacam...
9. Post Lasik Ectasia
It is a rare potentially
devastating complication after
refractive surgery including
LASIK and PRK.
It is characterized by a
progressive increase in myopia
and astigmatism.
10. Risk factors:
- Young age
- High myopia (>8 diopters Ds)
- Low corneal thickness
- Low residual stromal bed thickness
- Preexisting suspicious corneal topography, forme fruste keratoconus, and
pellucid marginal degeneration
- Positive family history of ectasia
18. Post Penetrating Keratoplasty Ectasia
Post-keratoplasty ectasia is characterized by increasing corneal steepening with
myopic shift and high irregular astigmatism, developing years or decades after PK,
mostly occurring in KC patients.
24. Cases can mimic post Lasik ectasia
(Decentered ablation)
▪ A decentered ablation can occur if the patient’s eye gradually begins to lose
fixation, the surgeon positions the patient’s head improperly, and the patient’s
eye is not precisely perpendicular to the laser treatment direction.
▪ A decentered ablation zone may pass undiagnosed during surgery and result in
irregular astigmatism.
▪ It is manifested by typical symptoms, including severe visual distortion, halos,
glare, monocular diplopia, and loss of best-corrected visual acuity.
25. By Pentacam
The decentration of the
ablation can be confirmed
by the decentered pattern of
the corneal power map in
the corneal topography
examination.
a) Localized decentered
thinning.
b) Localized decentered
flattening.
c) Associated steepening.