Presentation on theme: "Toric and Modern IOL Technology"— Presentation transcript:
1 Toric and Modern IOL Technology Dr Gagan KhannahOphthalmic SurgeonEastwood Eye SurgerySydney Eye HospitalStamford Grand3rd May 2009
2 Cataract and Refractive Surgery Cataract surgery and refractive surgery are now seen as a surgical spectrumSignificant advances in safety, technology, techniques and results,000 Cataract operations,000 Refractive operations>10% of >60yo have IOLsCataract surgery is very cost effective surgery
3 Two Residual ProblemsRoutine monofocal IOL cataract surgery results does not overcome:PresbyopiaAstigmatism
4 Treatment of Astigmatism Spectacles or Contact lensesExcimer Laser: LASIK or PRKIncisional Corneal Surgery: LRI or AKToric IOLsCorrect corneal astigmatism
5 Toric IOLsThe Staar plate haptic AA4203 IOL became the first FDA approved toric IOL in November 1998Poor rotational stability (>20%)
7 IOL Design Single piece and foldable Acrylic Placed within the capsular bagFor pre-existing corneal astigmatismBlue-light filtering technology6.0-mm opticInjector-style delivery similar to conventional monofocal IOLsAdhesive propertyPrevents rotation after implantationNOT AsphericThe 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 mustChoose the correct AcrySof® Toric IOL powerEnsure precise alignment of IOL within the eye relative to the patient’s axis of corneal astigmatismDesigned with axis marks on the posterior surfaceIOL placed and marks aligned precisely with the steep axis of the postincisional corneaIn 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 importantOff-axis rotation reduces the corrective cylinder powerFor every 1° of rotation, 3.3% of the lens cylinder power is lostFor 30° of rotation there is a complete loss of astigmatic correctionAdditional astigmatism or visual problems with greater than 30° of rotationThe 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 stabilityAverage rotation of less than 4° at six months post-opSTABLEFORCE® haptic design allows the IOL to conform to the capsular bagPromotes optimal placement and centration in different sized capsular bagsThe 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 availableChart shows the model numbers, the power at the IOL and corneal planes, and the recommended range of astigmatism correctionAdditional power options will be added in the future to address a broader range of astigmatic conditionsAspheric models to be released in AustraliaThe 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 successSuitable candidates are cataract patients with pre-existing corneal astigmatism > 0.75 D with the following characteristicsManual keratometry: steep and flat meridians ~90° apartCorneal topography: symmetrical astigmatismIntact capsular bag compatible with continuous curvilinear capsulotomy performed with in-the-bag placement of the IOLProper 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 keratometry2. Symmetrical astigmatism pattern (e.g., bowtie or wedge-type), as identified by corneal topography, and3. 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 powerUse manual keratometry and topography for magnitude, orientation, and type of pre-existing corneal astigmatismSubjective refraction data is not advised in order to avoid the influence of any lenticular astigmatism, which will be eliminated when the cataractous lens is removedThe 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 modelCalculatorConsiders the effect of incision location and surgically induced cylinder to make a more precise calculationDetermines the correct IOL model and optimal axis placement of the IOL in the capsular bagOnce 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 recommendedOutput data are displayed in a format suitable for printing forReference in the operating roomInclusion in the patient’s chartDetermines the optimal axis placement of the lens within the capsular bagCompensates for expected surgically induced astigmatismAllows for customization of important variables to accommodate individual surgeon preferencesThe 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 correctedSurgeons should enter a number that represents their actual historical average of surgically-induced cylinder and then customize itBased on clinical data, a default value of 0.5 D is provided as a starting pointEstimated 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 periodPatient in upright positionTwo reference marks placed at the limbus, 180 degrees apartUsed later to align the marking instrument for placement of axis marksAxis MarkingsDefine the optimal axis of IOL placementDetermined by the AcrySof® Toric IOL CalculatorUsing the reference marks as a guide, the patient’s eye is marked accurately at two positions, 180 degrees apartAxis 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.
20 Intraoperative IOL Alignment Gross alignmentInject the IOL into the capsular bagRotate the IOL clockwise, approximately 20° to 30° short of the intended final axis locationViscoelastic removalEnsure that the IOL does not rotate beyond the intended final axis locationCarefully remove viscoelastic from both the anterior and posterior sides of the lensFinal alignment of the IOLRotate the lens clockwise precisely to the intended axis of alignment as previously markedGross 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 astigmatismRoutine 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 optionsNo combination of Toric Multifocal yetAlways under promise and over deliver!!
23 Centration will become vital Future: Super IOLOne pieceAcrylicAsphericAccommodative or MultifocalToricPreloadedCentration will become vital