1. Management of Astigmatism - An overview
Dr. Haripriya Aravind
Aravind Eye Hospital, Madurai

2. Why? Surgery of cataract is now Keratolenticular Refractive surgery
Post op absence of optical correction desired
Objective is complicated when high astigmatism exists

3. Definition
It is condition of refraction where in, a point focus of light cannot be formed upon retina

4. Types Regular astigmatism Irregular astigmatism
Principal meridians are perpendicular
Irregular astigmatism
Principal meridians are not perpendicular

5. Regular Astigmatism With the rule astigmatism (W.T.R)
Vertical corneal meridian is steeper
Against the rule astigmatism (A.T.R)
Horizontal meridian is steeper
WTR 60° - 120°
ATR ° ° - 30°

6. Regular Astigmatism Oblique astigmatism 90° 120° 60° 150° 30° 0° 180°

7. Measurement
Retinoscopy
Keratometry
Corneal topography instruments

8. Astigmatism in Cataract Surgery
Pre-existing astigmatism
Cautery
Incision characteristics
Suture characteristics
Postoperative factors
use of steroids

9. Preexisting Astigmatism
Final astigmatic error depends to a large extent on pre-operative astigmatism
Place the incision at steeper meridian
Modify wound characteristics

10. Cautery
Excessive cautery causes
Scleral shrinkage
Scleral necrosis

11. Incision characteristics
Location
Length
Configuration of the wound

12. Location of the Wound
More anteriorly located wound - more induced astigmatism
Laterally located wound - less decay in A.T.R

13. Wound Length of Wound Configuration of Wound Astigmatism  length3
External configuration
Internal configuration

14. External configuration

15. INTERNAL CONFIGURATIONd b
a - b = beveled
c - d = Perpendicular
Three plane

16. INCISIONAL FUNNEL

17. Suture Characteristics
Length
Depth
Tightness
Suture Material
Suture Orientation

18. Length :Zone of compressionA B
A = B No Astigmatism

19. A B
A > B WTR

20. A B
A < B ATR

21. Tightness Of Suture Tight suture - increase in W.T.R
Loose suture - increase wound separation - increase A.T.R

22. Effect of Suture on Corneal Contour

23. Effect of Suture on Corneal
Contour

24. Depth Of Suture Bite
Superficial suture - cut through tissue - increase A.T.R
Finer suture like 10-0 Nylon to be placed at 90% depth

25. Suture Characteristics
Suture material
Non-absorbable suture causes less A.T.R decay
Silk suture degrades within 3 months - increase A.T.R
Suture orientation
Non-radial sutures cause lateral displacement - increase astigmatism

26. Correction of Post Cataract Surgery Astigmatism
Suture relaxation
Spectacles
Contact lens
LASIK
Surgery

27. Management Spectacles Suture relaxation
Main stay of treatment for majority of patients
Suture relaxation
Preferably after 3 months
Indicated when > 3 D W.T.R is present

28. Contact Lens Indications Variety Fitting
Irregular post operative astigmatism
Variety
Hard contact lens
Fitting
Difficult (especially in high astigmatism)

29. Surgery Astigmatic keratotomy Peripheral arcuate incisions
Opposite clear corneal incision
Toric IOL

30. Relaxing Incision - Principle

31. Barrier Concept

32. Coupling
Flat
Steeper
Steep
Flatter

33. Astigmatic keratotomy principles

34. Incisions in Astigmatic Keratotomy

35. Astigmatic Keratotomy
Timing
Depends on surgeons
During cataract surgery
A few months postop when postop refraction stabilises
Indications
Moderate to high level of astigmatism
Less aggressive management in with the rule astigmatism cases
Nomogram

36. Thornton Nomogram

37. Limbal Relaxing Incision
Corrects about 0.5 to 4 diopters of astigmatism
Can be performed at the time of cataract surgery or as an independent procedure

38. Modified Gills and Cayton Nomogram

39. Limbal Relaxing Incision
Location
Depth
Role of Pachymetry

40. Opposite clear corneal incision
Jeffrey Lever & Elie Dahan
Creating a second penetrating clear corneal incision opposite that made for IOL implantation

41. How does it work?
Penetrating corneal wound of certain length provokes astigmatism
TCCT-3.0mm D
5.2mm D
Adding an identical CCI opposite first enhances the flattening effect on the cornea
Placed on steepest axis and is self sealing

42. Toric IOL
Toric IOLs are created by incorporating a cylindrical correction on a spherical optic
Single-piece, plate haptic, foldable intraocular lenses

43. LASIK
A thin surface flap of the cornea is created using a microkeratome to expose underlying tissues and the excimer laser beam is applied to create the refractive ablation
Expense and non availability

44. “Correcting astigmatism is not a procedure that doctors are usually paid for
It is a value-added service because it means less dependency on glasses and better quality of vision”

45. Thank You