2. IOLs & Biometry Alireza Peyman, MD Isfahan University of Medical Sciences

3. Sir Nicholas Harold Lloyd Ridley 10 July 1906 25 May 2001

4. First IOL manufactured using Perspex on 29 November 1949 at St Thomas' Hospital, by the Rayner company. Approved for use in the USA by the Food and Drug Administration in 1981

5. Ridley used ECCE technique No gloves or microscope was availabel 20% failure rate

7. Sir Harold Ridley kneels as he receives knighthood from Queen Elizabeth II of England on February 9, 2000

8. IOLs Phakic –Angle supported –Iris claw –Sulcus Aphakic

9. IOLs PMMA Foldable –Hydrophilic –Hydrophobic –silicon Plate haptic, C loop, 3piece, 1piece,.. Spherical, Aspheric,.. Blue light filtering, UV filtering Multifocal, Accommodative Toric, …

10. Multifocal Refractive IOLs ReZoom™ intraocular lens, are designed with several optical zones

11. Apodized Diffractive Multifocal IOL Acrysof® ReSTOR® intraocular lens

12. Accommodative IOL Crystalens™ intraocular lens

13. IOL power selection is more important than IOL brand

14. IOL POWER CALCULATION

15. History of IOL power calculation Before 1975 the formula for iris-supported IOL power calculation was: P= 18 + (1.25*Ref) Errors of more than 1D occurred in over 50% Some large errors occurred

16. First IOL power formula was published in 1967 by Fyodorov and Kolonko. Subsequent formulas from Colenbrander, Hoffer, and Binkhorst incorporated ultrasound data In 1978 first regression formula published, this formula later evolved to SRK II in 1980

18. Regression formulas Regression formulas are derived empirically from retrospective analysis of data on many patients who have undergone surgery SRK is the most popular regression formula:

19. Resultant refractory error “P” is power for emmetropia “I” is inserted power –A change of 1.5 diopter implant power produces a change of approximately 1 D in final refraction.

20. 3 rd and 4 th generation formulas SRK/T Hoffer Q Holladay I Haigis Holladay II

21. Formulas are for in the bag IOL

22. WHICH FORMULA SHOULD USED?

23. AL < 22 short eye AL > 25 long eye

26. My opinion Axial LengthFormula <22 mmHoffer Q 22 – 24.5 mmSRK/T, Holloday I, and Haigis (mean) > 24.5SRK/T 28mmOptimized Haigis, Holladay II

27. For normal range all formulae are acceptable, the SRK/T is more popular For short eyes (hyperopic) use Hoffer Q For long eyes (myopic) use SRK/T In extreme cases Optimized Haigis, and Holladay II should utilized

28. ACCURATE BIOMETRY

29. Accurate AL measurement and keratometry is far more important than which calculation formula is used

32. SNR SNR > 2 is good if repeatable SNR 1.6 – 2 is borderline, considered OK if repeatable <1.6 is ERROR Repeat measurement at least 5 times

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