1. Toric and Modern IOL Technology
Dr Gagan Khannah
Ophthalmic Surgeon
Eastwood Eye Surgery
Sydney Eye Hospital
Stamford Grand
3rd May 2009

2. Cataract and Refractive Surgery
Cataract surgery and refractive surgery are now seen as a surgical spectrum
Significant advances in safety, technology, techniques and results
,000 Cataract operations
,000 Refractive operations
>10% of >60yo have IOLs
Cataract surgery is very cost effective surgery

3. Two Residual Problems
Routine monofocal IOL cataract surgery results does not overcome:
Presbyopia
Astigmatism

4. Treatment of Astigmatism
Spectacles or Contact lenses
Excimer Laser: LASIK or PRK
Incisional Corneal Surgery: LRI or AK
Toric IOLs
Correct corneal astigmatism

5. Toric IOLs
The Staar plate haptic AA4203 IOL became the first FDA approved toric IOL in November 1998
Poor rotational stability (>20%)

6. Toric IOLs Rayner T-flex® Toric Zeiss Acri.Comfort 646 TLC
Alcon AcrySof® Toric IOL

7. IOL Design Single piece and foldable Acrylic
Placed within the capsular bag
For pre-existing corneal astigmatism
Blue-light filtering technology
6.0-mm optic
Injector-style delivery similar to conventional monofocal IOLs
Adhesive property
Prevents rotation after implantation
NOT Aspheric
The AcrySof® Toric IOL is a foldable, single-piece IOL intended for placement within the capsular bag following cataract surgery in patients with pre-existing corneal astigmatism.
It is based on the proven AcrySof® Single-Piece Natural blue-light filtering technology. The AcrySof® Toric IOL features a fully functional 6.0-mm optic as well as STABLEFORCE® haptic design. The AcrySof® Toric IOL is designed to be delivered into the capsular bag using an injector-style delivery, just as conventional monofocal IOLs are implanted.

8. IOL Design – Optic Markings
Surgeons must
Choose the correct AcrySof® Toric IOL power
Ensure precise alignment of IOL within the eye relative to the patient’s axis of corneal astigmatism
Designed with axis marks on the posterior surface
IOL placed and marks aligned precisely with the steep axis of the postincisional cornea
In correcting astigmatism with the AcrySof® Toric IOL, surgeons must not only choose the correct AcrySof® Toric IOL power, but must also ensure that the IOL is precisely aligned within the eye relative to the patient’s axis of corneal astigmatism.

9. IOL Design – Rotational Stability
Lens stability is important
Off-axis rotation reduces the corrective cylinder power
For every 1° of rotation, 3.3% of the lens cylinder power is lost
For 30° of rotation there is a complete loss of astigmatic correction
Additional astigmatism or visual problems with greater than 30° of rotation
The importance of maintaining lens stability within the capsular bag cannot be overstated. Rotation of the IOL off axis reduces the corrective cylinder power of a toric IOL.
Generally, for every 1 degree of rotation, 3.3% of the lens cylinder power is lost. Therefore, 30 degrees of rotation could cause a complete loss of astigmatic correction, and more rotation than this may induce additional astigmatism and potentially increase visual problems for the patient.

10. IOL Design – Rotational Stability
STABLEFORCE® haptic design and adhesive nature of AcrySof® Toric IOL material provide high level of rotational stability
Average rotation of less than 4° at six months post-op
STABLEFORCE® haptic design allows the IOL to conform to the capsular bag
Promotes optimal placement and centration in different sized capsular bags
The AcrySof® Toric IOL is designed to deliver outstanding rotational stability within the capsular bag.
The STABLEFORCE® haptic design and the adhesive nature of the AcrySof® Toric IOL material combine to provide a very high level of rotational stability. This was demonstrated in the clinical study, which showed that the AcrySof® Toric IOL is stable within the capsular bag, with average rotation of less than 4 degrees 6 months after implantation.
It should be noted that the flexible STABLEFORCE® haptic design has another important benefit. It allows the IOL to conform to the capsular bag, promoting optimal placement and centration in capsular bags of different sizes. This makes the lens suitable for use in a wide variety of patients.

11. AcrySof® Toric IOL Models
Three AcrySof® Toric IOL models initially available
Chart shows the model numbers, the power at the IOL and corneal planes, and the recommended range of astigmatism correction
Additional power options will be added in the future to address a broader range of astigmatic conditions
Aspheric models to be released in Australia
The chart shown here depicts for each of the three AcrySof® Toric IOL models initially available: the model number, the power at the IOL and corneal planes, and the recommended range of astigmatism correction.
Additional power options will be added in the future to address a broader range of astigmatic conditions.

12. Patient Selection Criteria
Proper patient selection is critical to achieve success
Suitable candidates are cataract patients with pre-existing corneal astigmatism > 0.75 D with the following characteristics
Manual keratometry: steep and flat meridians ~90° apart
Corneal topography: symmetrical astigmatism
Intact capsular bag compatible with continuous curvilinear capsulotomy performed with in-the-bag placement of the IOL
Proper patient selection is critical to achieving successful outcomes with the AcrySof® Toric IOL.
Suitable candidates include those cataract patients with pre-existing corneal astigmatism greater than 0.75 D with the following characteristics:
1. Steep and flat meridians approximately 90 degrees apart, as determined by manual keratometry
2. Symmetrical astigmatism pattern (e.g., bowtie or wedge-type), as identified by corneal topography, and
3. An intact capsular bag that is compatible with having a continuous curvilinear capsulotomy (CCC) performed with in-the-bag placement of the IOL

13. IOL Power Selection Process
Determine the required spherical lens power
Use manual keratometry and topography for magnitude, orientation, and type of pre-existing corneal astigmatism
Subjective refraction data is not advised in order to avoid the influence of any lenticular astigmatism, which will be eliminated when the cataractous lens is removed
The process of selecting the appropriate AcrySof® Toric IOL model for a given patient starts with determination of the required spherical lens power. Surgeons should use their preferred method and formulae as for conventional monofocal IOLs to determine spherical power requirements for a patient.
The magnitude, orientation, and type of pre-existing corneal astigmatism to be treated are best determined by manual keratometry and topography; subjective refraction data is not advised in order to avoid the influence of any lenticular astigmatism which will be eliminated when the cataractous crystalline lens is removed.

14. Selecting an AcrySof® Toric IOL Model
The data are entered into the AcrySof® Toric IOL Calculator to determine the optimal model
Calculator
Considers the effect of incision location and surgically induced cylinder to make a more precise calculation
Determines the correct IOL model and optimal axis placement of the IOL in the capsular bag
Once biometry and manual keratometry are completed, the spherical power and K readings are then used to determine the optimal AcrySof® Toric IOL model by entering required data into the online AcrySof® Toric IOL Calculator. It is important to note that the Calculator takes into consideration the effect of incision location and surgically induced cylinder to make a more precise calculation. After entering all required information, the Calculator will determine the correct IOL model and the optimal axis placement of the IOL in the capsular bag.
The AcrySof® Toric IOL Calculator will be described and explained in greater detail later in this orientation program.

15. AcrySof® Toric IOL Calculator
Manual keratometry is recommended
Output data are displayed in a format suitable for printing for
Reference in the operating room
Inclusion in the patient’s chart
Determines the optimal axis placement of the lens within the capsular bag
Compensates for expected surgically induced astigmatism
Allows for customization of important variables to accommodate individual surgeon preferences
The Calculator provides critical information to assist the surgeon in precisely correcting astigmatism. It allows for customization of important variables to accommodate individual surgeon preferences and allows for precise surgical planning.

16. Estimated Surgically-induced Cylinder
Directly impacts the amount and/or axis of post-incisional astigmatism to be corrected
Surgeons should enter a number that represents their actual historical average of surgically-induced cylinder and then customize it
Based on clinical data, a default value of 0.5 D is provided as a starting point
Estimated Surgically Induced Cylinder (SIC) is an important variable since it directly impacts the amount and/or axis of post-incisional corneal astigmatism to be corrected. Surgeons should enter a number that represents as accurately as possible their actual historical average of surgically induced cylinder resulting from their customary surgical technique.
It is recommended that surgeons customize this important variable (much the same way a surgeon would customize their A-Constant) based upon their individual procedure and outcomes. A default value of 0.5 D is provided as a starting point based on data from the clinical study.

17. Marking of the Eye Two steps Axis Markings Reference Marking
Pre-induction period
Patient in upright position
Two reference marks placed at the limbus, 180 degrees apart
Used later to align the marking instrument for placement of axis marks
Axis Markings
Define the optimal axis of IOL placement
Determined by the AcrySof® Toric IOL Calculator
Using the reference marks as a guide, the patient’s eye is marked accurately at two positions, 180 degrees apart
Axis marking: After phacoemulsification, using the reference marks as a guide, the patient’s eye is marked accurately at two positions (180 degrees apart) that define the optimal axis of IOL placement as determined by the AcrySof® Toric IOL Calculator.

18. Reference Marking

19. Axis Marking

20. Intraoperative IOL Alignment
Gross alignment
Inject the IOL into the capsular bag
Rotate the IOL clockwise, approximately 20° to 30° short of the intended final axis location
Viscoelastic removal
Ensure that the IOL does not rotate beyond the intended final axis location
Carefully remove viscoelastic from both the anterior and posterior sides of the lens
Final alignment of the IOL
Rotate the lens clockwise precisely to the intended axis of alignment as previously marked
Gross alignment of the IOL should be made following its injection into the capsular bag. While it is unfolding, the surgeon rotates the IOL clockwise to approximately 20 to 30 degrees short of the intended final axis location.
During viscoelastic removal, the surgeon should pay special attention to ensure that the IOL does not rotate beyond the intended final axis location.
This is done by carefully removing all viscoelastic from both the anterior and posterior sides of the lens. Residual viscoelastic may allow the lens to rotate, causing misalignment of the IOL with the intended axis of placement.

21. Summary AcrySof® Toric IOL Good rotational stability
The presence of an online calculator brings a high level of precision and accuracy to the selection of the correct IOL model and optimal axis placement of the IOL. Provides flexibility in surgical planning for precise correction of astigmatism
Routine surgical technique except accurate marking of the eye, and precise alignment of the IOL within the capsular bag

22. Limitations Always under promise and over deliver!! Not Aspheric
Limited cylinder power options
No combination of Toric Multifocal yet
Always under promise and over deliver!!

23. Centration will become vital
Future: Super IOL
One piece
Acrylic
Aspheric
Accommodative or Multifocal
Toric
Preloaded
Centration will become vital

24. Thank You!