Pellucid marginal degeneration is a type of corneal ectasia that is different in diagnosis and treatment from keratoconus

1. Nel nome di Dio, ilNel nome di Dio, il
Compassionevole, ilCompassionevole, il
MisericordiosoMisericordioso

2. Pellucid MarginalPellucid Marginal
DegenerationDegeneration (Keratotorus)(Keratotorus)
· Mohamed Elkadim
· Ospedale Villa Igea
· March 2019
· 10.13140/RG.2.2.23693.18400

3. What is PMD ?
· band of corneal thinning 1 – 2 mm in width
which extends from the 4 – 8 o’clock
position.
· Between the thinned band and the limbus
there is a 1–2 mm wide region of uninvolved
cornea.

4. In comparison with Kc ,, patient with PMD
usually have good spectacle corrected
visual acuity.
KC PMD
Optical
zone is
spared

5. Why its important to diagnose ?
1. PMD is progressive disease regardless
of age .
2. Surgical treatment of PMD is different
from Kc.

6. How to DD PMD x Peripheral Kc ?

7. Clinical Findings
· Very high against the rule astigmatism
· BCVA is relative good
· No clinical signs of Kc
· Highest point is above the thinnest

8. https://webeye.ophth.uiowa.edu

9. Axial curvature map x x
· Butter fly pattern is not specific to PMD and could be
found also in KC.

10. Tangential curvature map ±
· PMD KC

11. Pachymetry map √ √
· Bell shaped appearance of thickness map is highly
specific for PMD

12. There is sometimes an overlap

13. KC

14. PMD
Note : regular keratometric map

15. ???

16. Treatment options of PMD

17. · Non surgical : Glasses / CL / Scleral CL
· Surgical :

18. 1-Techniques for mild cases

19. CXL for mild cases
· Results : (9 eyes) Stabilization for 1
year follow up , TA decrease by 0.7 D

20. PRK + CXL
TA decreased from -6.8 to -4.7 D

21. ICRS also for mild cases

22. 2- Tissue replacement group
(keratoplasty)

23. · © 2005 by the American Academy of
Ophthalmology

24. Crescent Tuck in Lamellar KP
· 2 eyes :
· RA : 17 D to 7 D then 3D with AK
· RA : 7D to plano

25. 3- Tissue Excision group
The concept is the cornea
developed elongation so excision of
a strip of thinned elongated tissue
will fix the problem

26. Wedge resection

27. (Eye & Contact Lens 2017;0: 1–5)
· 10 eyes (follow up 1-2 years)
· SIA : 13.0 ± 6.3 diopters (D).

28. 5

30. Busin et al.

31. 4- Tissue addition group
The concept is addition of tissue to
correct thinning of the cornea

32. Intrastromal lamellar KP
· Astigmatism reduced from 6 to 4.5 D.

34. · 1 eye :
· TA decreased from 20.5 D to 11 D
· ( suturing the wound may play a
role in correction !!)

35. Bandage intra stromal KP

36. Techniques for PMD ???
Glasses
CL
CXL / PRK
Tissue Excision
Tissue Addition
Tissue
Replacement
(keratoplasty)

37. · Barraquer´s thickness laws : “whenever tissue is either added to the periphery
of the cornea or removed from its central part, a corresponding flattening is obtained
and vice-versa, whenever tissue is either added to the center or removed from its
periphery, a corresponding increase in curvature is obtained”

38. Tissue addition or excision ???
PMD = Elongation + thinning
·
· Excision Addition

39. Is there tissue loss or tissue
gain ???

40. Thining + Elongation = Stretch
↓ tissue volume + ↑ tissue volume
=
No change in volume ??
Is there tissue loss or tissue
gain ???

41. Tissue rearrangement √
· If there is no change in tissue volume
· Both tissue addition and tissue excision
techniques are wrong ??
· A surgical technique based on tissue
reconfiguration will be the ideal ??

42. My suggested technique : Thin lamellar wedge
resection and re-implantation
Elkadim Mohamed 3/2019
Tanta University , Egypt
DOI: 10.13140/RG.2.2.23693.18400

43. Conclusion
· PMD is a rare disease
· Despite there is overlap between PMD and
peripheral Kc , affection of optical zone and
pachymetry map could be a guide to the
diagnosis.
· Till the moment here is no gold standard
surgical technique for management of PMD.