CORRECTION C O OF ASTIGMATISM DURING CATARACT SURGERY Abdallah dllh K. Hassouna, M.D. Sherein S. Wahba, M.D. Ain Shams University 2009
Main target What is the main target for all phaco surgeons?
Main Target Removal of the crystalline lens ( whether cataractous or not ) with proper IOL implantation combined with other procedures to correct preoperative astigmatism to achieve full emmetropia
Astigmatism Natural ldi distribution ib i of astigmatism i 0-1D 45% 1.25-2.5 D 45% >2.5 D 10% Value of minimizing astigmatism To achieve best UCVA Pre-requisite requisite IOLs for multifocal & accommodative
Methods of correction of astigmatism at the time of cataract surgery Wound placement Opposite clear corneal incisions Astigmatic keratotomy Limbal relaxing incisions (LRIs) LASIK Toric intraocular Lens
Astigmatism Preoperative evaluation of corneal astigmatism X Use Keratometry, IOL master or elevation based topography Not: refraction (Corneal & lenticular astigmatism) neither Placido based topography (tilt, error in calculation)
Astigmatism < 1 D Steep meridian incision 2 D Opposite clear corneal incisioni i < 3.5 D Limbal relaxing incisions 1.4-2.3 D Staar toric IOL 1-2 D AcrySof toric IOL (T3-T5) 2.5 4 D AcrySof toric IOL (T6-T9) Up to 12 D Combinations and piggybacking
Toric Intraocular Lenses
Toric IOLs Advantages: No additional surgical steps Predictable Minimal cataract wound Ideal candidate: Regular astigmatism Astigmatism between 1-2.3 D
Staar Toric AcrySof Toric Plate Silicon Haptic Single piece hydrophobic acrylic Anterior toric Posterior toric 24 % > 10 rotation Average 4 rotation Usually stabilize within 48h Usually stabilize after OVD removal Corrects: 1.4 or 2.3 D @ Corrects: 1.03, 1.55 or 2.06 D corneal plane @ corneal plane Calculator: no SIA compensation Calculator: SIA compensation Longer experience Shorter experience
Complications Decentration Sublaxation
Rotational stability Generally, for every 1 of rotation, 3.3% of the IOL cylinder power is lost 30 of rotation may completely negate cylinder power correction of a toric IOL Further rotation potentially increases visual problems for the patients
First Toric IOL Three-piece (PMMA) Toric curve on the concave back surface Implanted through a incision 5.7 mm corneal (Schimizu Schimizu, et al 1992)
Second Toric IOL One-piece PMMA lens Over length of 12.5 mm Modified C-loop haptics 5.25 mm round optic (Grabow 1997)
Plate haptic First Foldable IOL Foldable silicon Staar Toric IOL Biconvex 6mm optic Sphero-cylindrical l anterior surface Spherical posterior surface
Ideal candidate Regular astigmatism Astigmatism between 1.5-3.5 D Prerequisites The cataract neutral Advantages Predictable wound minimal cataract wound should No additional surgical step be astigmatically
Complications Decentration Sublaxation Lens rotation and axis shift: 10 results in cylinder reduction of 2/3 20 results in cylinder reduction of 1/3 Partial reduction with up to 30 misalignment
2003 2005 Staar Toric OUR AIM To study the best way of reducing PEA during cataract surgery
2003 2005 comparing between construction of the wound in the steep meridian, LRIs, and toric IOLs as regards the efficacy, predictability, stability, and safety
Patients and Methods This study included 45 eyes of 42 patients with a mean age 53.9 years divided into 3 parts: Part I: Included d 15 eyes underwent cataract t surgery with the incision site on the steep meridian Part II: Included 15 eyes underwent LRIs during cataract surgery Part III: Included 15 eyes underwent cataract surgery with implantation of a Staar Toric IOL
Calculation of the Toric IOL Power Staar Toric IOL software
Staar Toric IOL Inserted through an injector (2.8-3.0 mm) Has two marks on should be aligned with the steep axis
Visual Outcome Mean % of change of UCVA 7.57 4.42 4.54 Part I Part II Part III Comparison between the three parts as regards the mean percentage of change of UCVA
Keratometric astigmatism 2.5 2.38 Keratometric Astigmatism 2 1.5 1.86 1.36 1.67 1.98 1.83 1 0.5 0 Part I Part II Part III Study groups Preop k.astigmatism Postop k.astigmatism 3m Comparisons between the mean preop. keratometric astigmatism, and mean postop. keratometric t astigmatism at 3 months among the study groups
Steep meridian LRIs Toric IOL Preoperative postoperative
Refractive astigmatism 3 2.5 2 2.11 2.63 2.22 Refractive Astigmatism 1.5 1 0.970.93 1.181.23 0.5 0.480.48 0 Part I Part II Part III Study groups Preop R.Astigmatism Postop R.Astigmatism 3m Postop R.Astigmatism 9m Comparisons between the mean preop refractive astigmatism and mean postop Comparisons between the mean preop. refractive astigmatism, and mean postop. refractive astigmatism at 3 months, and at 9 months among the study groups
Astigmatism reducing effect Mean % of change of postop. refractive astigm atism 1 0.9 0.8 0.65 0.6 0.4 0.2 0 1.50-2.25 D 2.50-3.50 D Comparison between the two astigmatism groups in part III as regards the mean percentage of change of postoperative refractive astigmatism
Postoperative Procedure Orientation of the axis of the IOL assessed by: Dilated pupil on SL examination The guide of the Staar software program Rotation of IOL Five IOLs were within 5 degrees of the intended axis Six IOLs rotated 10 degrees Two IOLs rotated 15 degrees One IOL rotated 20 degrees In all cases, the toric IOL remained within 30 degrees of rotation
2008 2009 Evaluation of AcrySof Toric IOL As regards the efficacy, predictability, stability, and safety
Patients & Methods This study included 12 eyes of 12 patients implanted with Acrysof Toric IOL Mean age of patients was 50.7 years Male Female 75% (3/1) No previous eye pathology or surgery
AcrySof Toric IOL Rotational stability STABLEFORCE haptic design Adhesive properties of acrylic material
Posterior Surface Toricity
Corrective Cylinder options
AcrySof Toric IOL calculator
Marking of the eye
Marking of the eye
Precise on- axis placement Gross alignment of the IOL Viscoelastic removal Final alignment of the IOL
Visual Outcome
Postoperative complication Rotation of IOL Ten IOLs were within 5 degrees of the intended axis Two IOLs rotated 10 degrees In all cases, the toric IOL remained within 30 degrees of rotation
Conclusion These preliminary results show that toric IOLs implantation during cataract surgery is effective and a predictable procedure in correction of PEA
BUT Cost ineffective (EXPENSIVE)
2009 Opposite Clear Corneal Incisions i
2009 Opposite Clear Corneal Incisions 2 standard cataract incisions are made 180 apart along the steep meridian
Opposite Clear Corneal Incisions Predictable? and effective in providing an enhanced effect over asingle CCI for correcting PEA in cataract surgery Steep axis marked seated at the slitlamp with the patient 2.75 mm incision for astigmatism of 1.0 to 1.75 D 3.2 mm incision for astigmatism >1.75 D
Opposite Clear Corneal Incisions No need for special diamond knife No need for expensive IOL Easy reproducible technique
Opposite Clear Corneal Incisions Lever and Dahan reported a mean astigmatism correction of 2.06 D with incisions ranging from 2.8 to 3.5 mm In our hand up to 2D of astigmatism correction with 3.0 keratome Stability?
Thank you for your attention