Refractive Lens Surgery

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44 D.D. Koch · L.Wang Fig. 5.4. Numerical view map from the Humphrey Atlas device those for the clinical history method, indicating better prediction performance of the Eff RP adj [7]. ∑ Adjusted annular corneal power: some CVK devices provide values for corneal power at incremental annular zones. Modification of the average of curvatures from certain annular zones may improve the accuracy of corneal power estimation. Using the Humphrey Atlas device, in hyperopic LASIK eyes, the average of curvatures at the center and the 1-, 2- and 3-mm annular zones (AnnCP) from the numerical view map can be modified using the following formula (Fig. 5.4) [14]: Adjusted AnnCP = AnnCP + 0.19 RC – 0.4 (hyperopia) Further studies are needed to validate this method. ∑ Adjusted keratometry: if there is no CVK available, for myopic LASIK eyes, keratometric values may be used and modified as follows [9]: Adjusted keratometry = keratometry – 0.24 RC + 0.15 (myopia) Randleman et al. [12] studied the results of cataract surgery in ten post-LASIK eyes and found that most accurate values were adjusted keratometry values in three of ten eyes, clinical history method also in three of ten eyes, and contact lens method in two of ten eyes.
5.3.2 Methods Requiring no Historical Data 5.3.2.1 Contact <strong>Lens</strong> Over-refraction Using this method, the corneal power is calculated as the sum of the contact lens base curve, power, and the difference between manifest refraction with and without a contact lens. Zeh and Koch evaluated this method in cataract patients who had normal corneas and found acceptable accuracy for eyes with Snellen visual acuity of 20/70 or better [15]. Unfortunately, this method appears to be less accurate in eyes that have undergone corneal refractive surgery. Presumably, this is due to the mismatch between the contact lens and the modified corneal shape. Our experience with this method has been disappointing,and this has been reflected in several other series as well [7, 16–18]. 5.3.2.2 Mean Central Corneal Power from CVK Certain CVK devices provide mean values for central corneal power, such as the Eff RP from the EyeSys device and the average central power within the entrance pupil from the TMS system [19]; these values overcome some of the limitations of using keratometric or simulated keratometric values and can be used in eyes that have undergone incisional keratorefractive surgery. However, they are inaccurate in post-PRK and post-LASIK eyes due to the above-mentioned inaccuracy of using 1.3375 as a standardized value for corneal refractive index [9]. In a recent study, Packer and colleagues [20] evaluated the efficacy of Eff RP in determining the central corneal power in IOL power calculation after incisional and thermal keratorefractive surgery. With the double-K Holladay 2 formula, they found that 80% of the eyes achieved postoperative refraction within ±0.50 D of emmetropia. Chapter 5 IOL Calculations 45 5.3.2.3 Modified Maloney Method Maloney proposed a method of modifying the corneal power at the center of the Humphrey Atlas axial topographic map (Robert K. Maloney, personal communication, October 2002); we have modified it slightly based on our retrospective data [7]: Central power = [central topographic power ¥ (376/337.5)] – 6.1 where central topographic power is simply the power with the cursor in the center of the topography map (Fig. 5.5). This method converts the corneal central power obtained from corneal topography back to the anterior corneal power, and then subtracts the posterior corneal power (6.1 D). In a previous study, based on a retrospective study of 11 eyes that had previously undergone myopic LASIK and subsequently cataract surgery with implantation of the SA60AT IOLs by one surgeon [7], we found that the variances of the IOL prediction error for the Maloney method were significantly smaller than those by the clinical history method, indicating that, with appropriate modification, this method might provide more consistent results. Further studies are needed to validate this modified Maloney method. 5.3.2.4 Adjusting Corneal Power using a Correcting Factor With assumption of axial myopia in most patients (i.e., amount of refractive correction is correlated to the axial length of eye), correcting factors were proposed to calculate corneal power according to the axial length of the eye [21]. Further studies are required to evaluate the accuracy of this method.
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Refractive Lens Surgery I. H. Fine
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Editors I. Howard Fine, MD Mark Pac
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Preface The first recorded time a h
Page 8 and 9: X Contents Chapter 14 AcrySof ReSTO
Page 10 and 11: Contributors Jorge L. Alio, MD, PhD
Page 12 and 13: 1 The Crystalline Lens as a Target
Page 14 and 15: 2 CORE MESSAGES Refractive Lens Exc
Page 16 and 17: na that have been observed with som
Page 18 and 19: piration through two separate incis
Page 20 and 21: 6 R.S. Hoffman · I.H. Fine · M. P
Page 22 and 23: 8 R.S. Hoffman · I.H. Fine · M. P
Page 24 and 25: 10 R.S. Hoffman · I.H. Fine · M.
Page 26 and 27: 12 M. Packer · I.H. Fine · R.S. H
Page 36 and 37: 22 J.T. Holladay 4.1 Introduction T
Page 38 and 39: 24 J.T. Holladay but only seven pre
Page 40 and 41: 26 J.T. Holladay from morning to ni
Page 42 and 43: 28 J.T. Holladay 4.3.2.2.3 Corneal
Page 44 and 45: 30 J.T. Holladay rienced this condi
Page 46 and 47: 32 J.T. Holladay many of these pati
Page 48 and 49: 34 J.T. Holladay IOL eRx V 1336 =
Page 50 and 51: 36 J.T. Holladay raised. A more tho
Page 52 and 53: 38 J.T. Holladay rior segment laser
Page 54 and 55: 40 D.D. Koch · L.Wang corneal refr
Page 56 and 57: 42 D.D. Koch · L.Wang Table 5.1. M
Page 60 and 61: 46 D.D. Koch · L.Wang Fig. 5.5. Ce
Page 62 and 63: 48 D.D. Koch · L.Wang ∑ Double-K
Page 64 and 65: 50 L.D. Nichamin surgeon the abilit
Page 66 and 67: 52 L.D. Nichamin Table 6.1. The Nic
Page 68 and 69: 54 L.D. Nichamin 3.2 mm, its neglig
Page 70 and 71: 56 L.D. Nichamin Fig. 6.4. The Nich
Page 72 and 73: 58 L.D. Nichamin References 1. Anon
Page 74 and 75: 60 S. Bylsma aphakic state. In cont
Page 76 and 77: 62 S. Bylsma length),underwent full
Page 78 and 79: 64 S. Bylsma K-Astigmatism
Page 80 and 81: 66 S. Bylsma STIOL in the reversed
Page 82 and 83: 68 S. Bylsma about the dynamics at
Page 84 and 85: 8 Correction of Keratometric Astigm
Page 86 and 87: Fig. 8.2. AcrySof toric IOL implant
Page 88 and 89: Fig. 8.3. Mean absolute residual cy
Page 90 and 91: References 1. Hoffer KJ (1980) Biom
Page 98 and 99: 10 The Eyeonics Crystalens Steven J
Page 100 and 101: Fig. 10.3. Under binocular conditio
Page 102 and 103: Fig. 10.6. Anterior movement of the
Page 104 and 105: Fig. 10.7. One- and 3-year data fro
Page 106 and 107: 10.6 Postoperative Considerations C
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10. Dell SJ (2004) Objective eviden
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100 N.X. Nguyen · A. Langenbucher
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12 CORE MESSAGES Synchrony IOL H. B
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Fig. 12.1. The single-piece silicon
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12.5 Clinical Results Clinical tria
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Fig. 12.6. Retroillumination photog
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References 1. Fisher RF (1973) Pres
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124 F.M. Sarfarazi 13.1 The Nature
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126 F.M. Sarfarazi Fig. 13.4. Lens
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128 F.M. Sarfarazi Fig. 13.5. Mecha
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130 F.M. Sarfarazi Fig. 13.9. Secon
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132 F.M. Sarfarazi Fig. 13.14. Sche
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134 F.M. Sarfarazi Fig. 13.18. Work
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136 F.M. Sarfarazi References 1. Ma
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138 A. Mirshahi · E.Terzi · T. Ko
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15 The Tecnis Multifocal IOL Mark P
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Fig. 15.1. The Alcon AcrySof multif
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Fig. 15.4. Multifocal vs. monofocal
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16 Blue-Light-Filtering Intraocular
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Fig. 16.2. Cultured human RPE cells
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tion to benefiting from less exposu
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16.7 Blue-Light-Filtering IOLs and
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15. Marshall J, Mellerio J, Palmer
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17 CORE MESSAGES The Light-Adjustab
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Fig. 17.2 a-c. Cross-sectional sche
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17.4 Animal Studies Dr. Nick Mamali
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Fig. 17.8. A laser interferogram (l
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enhanced visual function that remai
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13. Mather R, Karenchak LM, Romanow
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174 S. Norrby Fig. 18.1. Small cale
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176 S. Norrby Fig. 18.3. Scheimpflu
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178 S. Norrby Fig. 18.4. Schematic
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180 S. Norrby there was fibrin form
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182 S. Norrby material had a Young
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184 S. Norrby Koopmans et al. [28]
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186 S. Norrby 40. De Groot JH, Zuru
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188 L. Nordan · M. Morris regular
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190 L. Nordan · M. Morris produce
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20 CORE MESSAGES Bimanual Ultrasoun
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for an irrigating manipulator or ch
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5. Tsuneoka H, Shiba T, Takahashi Y
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200 J.L. Alio · A. Galal · J.-L.R
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22 CORE MESSAGES The Infiniti Visio
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Fig. 22.3. The AquaLase handpiece u
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23 CORE MESSAGES The Millennium Ros
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Fig. 23.1. Bausch & Lomb’s new cu
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Fig. 23.2. Advanced flow system car
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Fig. 23.5. Pulse or burst mode with
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24 CORE MESSAGES The Staar Sonic Wa
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Fig. 24.2. The tip undergoes compre
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the sonic tip moves back and forth
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25 CORE MESSAGES AMO Sovereign with
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Fig. 25.3. Schematic diagram of cav
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the Sovereign Compact (see Fig. 25.
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234 M. Packer · R.S. Hoffman · I.
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27 Conclusion: The Future of Refrac
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240 Subject Index Contrast sensitiv
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242 Subject Index P Pachymetry 53,
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