Toric IOls

update on toric IOLs

1. Toric IOLs overview and current clinical outcomes in patients with regular astigmatism 14/2/18 Nimrod Dar Ehud Assia

2. I ntroduction In modern cataract surgery, spectacle freedom is becoming more and more important 20% to 30% of patients who have cataract surgery have corneal astigmatism of 1.25D or higher and approximately 10% of patients have 2.00 D or higher Patients are 34 times more likely to use spectacles per diopter of astigmatic error in the better eye Toric intraocular lenses: historical overview, patient selection, IOL calculation, surgical techniques, clinical outcomes, and complications. Nienke Visser , Noël J. C. Bauer, Rudy M. M. A. Nuijts J Cataract Refract Surg. 2013 Apr; 39(4): 624–637

3. The beginning In 1992, Shimizu designed the first toric IOL, it was a 3-piece, nonfoldable PMMA, oval optic and loop haptics, requiring a 5.7 mm incision In 1994, Shimizu introduced the first foldable 1-piece toric IOL, it was made of silicone and required 3.2 mm incision The first clinical results with these IOLs were promising; 23% of patients achieved UDVA of 20/25 or better compared Vs 4 % of patients with a standard IOL The problem was: high postoperative rotation rate (> 10⁰ in 20% to 30% of eyes)

4. D esign Toric IOLs are made of hydrophobic acrylic, hydrophilic acrylic, silicone, or PMMA Two haptic designs: plate-haptic and loop-haptic

5. F requently used Toric IOLs 1. Staar Toric IOL ( Staar Surgical, Monrovia, Ca ) The first toric option approved in the US A silicone plate haptic design IOL, 3.0 mm clear corneal incision T he axis of toric power is marked with 2 hash marks 2 width available :10.8 mm and 11.2 mm Disadvantages: Plate haptic (fit in the capsular bag ..) Silicone (ant. Capsular fibrosis, rotation)

6. 2. AcrySof Toric IOL (Alcon Labs, Fort Worth, Tx ) A 1-piece, hydrophobic acrylic lens with a yellow chromophore, 6 mm optic, o verall Length 13 mm, requires 2.2 mm incision The IQ Toric version of this lens is aspheric The lens has 3 axis marking dots on either side of the  optic, showing the steep axis of toric power W ide range of astigmatism-correcting powers : 7 cylinder powers to treat 0.75 D to 4.11  D of astigmatism

7. 3. AMO Tecnis Toric IOL (Abbott Medical Optics, CA) 1-piece, aspheric, hydrophobic acrylic,  2.2 mm incision , square edge Cylinder Powers : 1.03 D to 4.11 D L ess chromatic aberration

8. Rotation of the IOL For every degree of misalignment, about 3 percent of the lens cylinder power is lost A misalignment of more than 10 degrees is generally regarded as the indication for surgical repositioning Several factors may influence IOL rotation : Adhesion IOL diameter Haptic design Toric intraocular lenses: historical overview, patient selection, IOL calculation, surgical techniques, clinical outcomes, and complications. Nienke Visser, Noël J. C. Bauer, Rudy M. M. A. Nuijts J Cataract Refract Surg. 2013 Apr; 39(4): 624–637

9. 1. Adhesion After implantation in the capsular bag, the anterior and posterior capsules fuse with the IOL, preventing IOL rotation In vitro and rabbits studies showed the strongest IOL–capsular bag adhesions for acrylic IOLs, followed by PMMA and silicone Extracellular matrix proteins such as fibronectin, may be involved in IOL adhesion to the capsular bag, and different IOL biomaterials show differences in affinity to proteins (acrylic > silicone) Toric intraocular lenses: historical overview, patient selection, IOL calculation, surgical techniques, clinical outcomes, and complications. Nienke Visser, Noël J. C. Bauer, Rudy M. M. A. Nuijts J Cataract Refract Surg. 2013 Apr; 39(4): 624–637

10. 2. Diameter Overall diameter has been shown to be a major factor in the prevention of IOL rotation Chang* compared 2 sizes of the Staar IOL - 10.8 and 11.2 mm in diameter 10% of the longer IOLs rotated more than 10 degrees compared with 45% of the shorter IOLs * Chang DF. Early rotational stability of the longer Staar toric in- traocular lens; fifty consecutive cases. J Cataract Refract Surg 2003; 29:935–940

11. 3. Haptics RCT by Patel* showed that postoperative rotation was significantly higher with loop-haptic IOLs than with plate-haptic IOLs: 6.8 degrees versus 0.6 degree A symmetric fusion of the capsular bag with the IOL haptics ? In 2011 Prinz + compared plate-haptic and loop-haptic acrylic IOLs and did not find a significant difference in postoperative rotation * Patel CK, Ormonde S, Rosen PH, Bron AJ. Postoperative intra- ocular lens rotation: a randomized comparison of plate and loop haptic implants. Ophthalmology 1999; 106:2190–2195; + Prinz A, Neumayer T, Buehl W, Vock L, Menapace R, Findl O, Georgopoulos M. Rotational stability and posterior capsule opacification of a plate-haptic and an open-loop-haptic intraoc ular lens. J Cataract Refract Surg 2011; 37:251–257

12. Patients selection Most studies of toric IOLs have selected patients with at least 1.00 to 1.50 D of corneal astigmatism I rregular astigmatism is a relative contraindication … Other relative/absolute contraindication : Fuchs endothelial dystrophy or another corneal dystrophy (KP in the future?) P otential capsular bag instability : P seudoexfoliation syndrome T rauma-induced zonulysis

13. Lens calculating V arious methods to measure corneal astigmatism- Automated/manual keratometry , corneal topography, and Scheimpflug imaging Scheimpflug imaging has the advantage of measuring both anterior and posterior corneal surfaces The posterior cornea acts as a minus lens and affects differently the WTR (decreasing astigmatism by 0.5 D) and ATR (increasing astigmatism by 0.3 D) Koch had incorporated the effect of the posterior corneal surface in toric IOL calculations Toric intraocular lenses: historical overview, patient selection, IOL calculation, surgical techniques, clinical outcomes, and complications. Nienke Visser , Noël J. C. Bauer, Rudy M. M. A. Nuijts J Cataract Refract Surg. 2013 Apr; 39(4): 624–637

14. Lens calculating - SIA The expected amount of surgically induced astigmatism (SIA) must be incorporated into the toric IOL power calculation T he amount of SIA is difficult to predict .. SIA depends on serval factors: The location of the incision The size of the incision A mount of preoperative corneal astigmatism S uture use P atient age

15. Methods S ystematic review and meta-analysis, 8/2015 Only RCTs comparing the result after toric versus non-toric IOL implantation in patients with preoperative regular corneal astigmatism and cataract 13 studies included, 707 eyes were randomized to toric IOL implantation and 706 eyes to non-toric IOL implantation Of those implemented with non-toric IOL, 225 eyes received relaxing incisions The level of preoperative corneal astigmatism was approximately 0.75 to 3 D in the included RCTs

16. Un-corrected distance visual acuity Each letter counts 0.02 units when visual acuity is tested using the logMAR chart at a distance of 20 feet

17. Results - UCDVA For patients randomized to toric IOL implantation, 35.2% did not achieve 20/25 UCDVA versus 60.4% in patients randomized to non-toric IOL (in both sub-groups) The difference in UCDVA between eyes randomized to toric or non-toric IOL was highly significant ( RR, 0.59; 95% CI, 0.50e0.70; P < 0.00001)

18. Results - d istance s pectacle independence The number of patients who required spectacles for distance viewing (sometimes.. ) was significantly lower in patients randomized to toric IOL implantation (29.7%) VS the non-toric IOL implantation (53.2%) (RR, 0.51; 95% CI, 0.36-0.71 ) Again, There was no difference between subgroups (toric vs. non-toric, toric vs. non-toric plus relaxing incision)

19. Results - residual astigmatism

20. More results There was no significant difference between the groups regarding post-operative complications On average, the toric IOLs rotated less than 5 degrees except for 1 IOL ( Lentis Unico - removed from the market) There were no significant differences between the amount of residual astigmatism at 3 and 6 months follow-up in the toric group ( P=0.61 )

21. Prediction of refractive outcomes R esidual astigmatism is still not always predictable Reasons : Intraocular lens tilt IOL rotational misalignment U nexpected surgically induced astigmatism (SIA ) Various studies have emphasize the importance of net corneal astigmatic power

22. Toric calculators There are different toric calculators available : The toric online calculator by Alcon uses a fixed ratio to calculate the estimated IOL toric power at the corneal plane Holladay toric calculator uses the predicted effective lens position to determine the toric IOL power at the corneal plane The Baylor toric nomogram , described by Koch , takes into account the effect of the posterior cornea (WTR and ATR differences..), and it can be used in conjunction with standard toric IOL calculators The Barrett toric calculator uses the ELP of the Barrett Universal II formula together with a mathematic model for the posterior cornea

23. Retrospective case series Aim: To evaluate and compare the accuracy of different methods to measure and predict post-operative astigmatism with toric IOLs implantation Three devices were used: IOLMaster 500 (PCI) Lenstar LS 900 (OLCR) Placido disk–based Atlas corneal topographer (sim/mean K) simulated K= values along the steepest and flattest meridians at the central 3.0 mm mean K= values from all measured points within the central 3.0 mm

24. Methods of calculation evaluated: 1. The online toric calculator by Alcon with and without the Baylor toric IOL nomogram adjustment 2. The Holladay toric calculator with and without the Baylor toric IOL nomogram adjustment 3. The online Barrett toric calculator

25. Evaluation of the error in predicted residual astigmatism The predicted residual astigmatism at the corneal plane was calculated by : The assumed toric IOL cylinder power at the corneal plane + Measured corneal astigmatism taken by each device The error in the predicted residual astigmatism was calculated by : Postoperative subjective refraction at the corneal plane - Predicted residual astigmatism at the corneal plane

26. Proportion of eyes with absolute error in predicted residual astigmatism below or equal to 0.50 D, 0.75 D, and 1.00 D

27. Conclusions The PCI and OLCR keratometers were better than the corneal topographer The Baylor toric IOL nomogram significantly reduced errors in residual astigmatism The OLCR device and the Barrett toric calculator provided the lowest residual astigmatism prediction errors

28. A new regression formula ( Abulafia -Koch) that calculates an estimated net corneal astigmatism using standard K measurements (based on the anterior cornea)

29. Immerging Technology Image-guided system for Toric Lens Implantation Alcon’s VERION ™   SensoMotoric Instruments’s SG3000