1) Secondary ectasia refers to corneal shape changes caused by external factors like previous refractive surgery or corneal transplantation. 2) Post-LASIK ectasia is a rare complication characterized by progressive myopia and astigmatism due to thinning and protrusion of the cornea. Risk factors include young age and pre-existing thin corneas. 3) On Pentacam, early post-LASIK ectasia shows mild corneal thinning and elevation changes mostly in the inferior cornea, while advanced cases resemble keratoconus with significant steepening and irregularity.

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

3. Some Corneal Problems need further
investigations to be diagnosed..

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

7. Post Lasik Ectasia
But First, We should know the normal Postlasik
Pentacam...

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

11. By Pentacam
Topographically;
Two stages:
1) Early post-Lasik ectasia.
2) Established post-Lasik ectasia.
3) Advanced post-Lasik ectasia.

12. Early post-Lasik ectasia
There is a mild
decrease in
corneal thinning
accompanied by
focal increase in
front and back
elevation, mostly
inferior.

13. Established post-Lasik ectasia.
There is a mild
increase in
irregular
astigmatism
accompanied
by focal
steepening,
often
inferiorly.

15. Advanced post-Lasik ectasia
In advanced
cases, the
changes cannot
be differentiated
from
Keratoconus

17. Take care of the other eye

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.

19. Diffuse corneal ectasia after
penetrating keratoplasty

20. Focal inferior corneal ectasia after
penetrating keratoplasty

21. Scar related ectasia

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.

28. By Aberrometry

29. Thank You