Refractive Lens Surgery

More documents

Recommendations

Info

30 J.T. Holladay rienced this condition may cause intolerable anisometropia and require further surgery. Monocular cataracts allow fewer choices for the desired postoperative refraction, because the refractive status of the other eye is fixed. The general rule is that the operative eye must be within 2 D of the non-operative eye in order to avoid intolerable anisometropia. In most cases this means matching the other eye or targeting for up to 2 D nearer emmetropia, i.e. if the non-operative eye is –5.00 D, the target would be –3.00 D for the operative eye. If the patient is successfully wearing a contact lens in the non-operative eye or has already demonstrated his ability to accept monovision, an exception can be made to the general rule. It should always be stressed, however, that should the patient be unable to continue wearing a contact,the necessary glasses for binocular correction may be intolerable and additional refractive surgery may be required. 4.3.2.4 Special Limitations of Intraocular <strong>Lens</strong> Power Calculation Formulas As discussed previously, the third-generation formulas (Holladay 1, Hoffer Q and the SRK/T) and the new Holladay 2 are much more accurate than previous formulas the more unusual the eye. Older formulas such as the SRK1, SRK2 and Binkhorst 1 should not be used in these cases. None of these formulas will give the desired result if the central corneal power is measured incorrectly. The resulting errors are almost always in the hyperopic direction following keratorefractive surgery, because the measured corneal powers are usually greater than the true refractive power of the cornea. To complicate matters further, the newer formulas often use keratometry as one of the predictors to estimate the ELP of the intraocular lens. In patients who have had keratorefractive surgery, the corneal power is usually much flatter than normal and certainly flatter than before the keratorefractive procedure. In short, a patient with a 38-D cornea without keratorefractive surgery would not be expected to be similar to a patient with a 38-D cornea with keratorefractive surgery. Newer IOL calculation programs are now being developed to handle these situations and will improve our predictability in these cases. 4.3.3 Intraoperative Evaluation 4.3.3.1 Intraoperative Visualization and Corneal Protection Intraoperative visualization is usually more difficult in patients with previous RK than in the normal cataract patient and is somewhat similar to severe arcus senilis or other conditions that cause peripheral corneal haze. The surgeon should be prepared for this additional difficulty by making sure that the patient is lined up to visualize the cataract through the optical zone. This usually means lining the microscope perpendicular to the center of the cornea, so that the surgeon is looking directly through the optical zone at the center of the cataract. When removing the peripheral cortex, the eye can be rotated so that visualization of the periphery is through the central optical zone. It is also prudent to coat the endothelium with viscoelastic to minimize any endothelial cell loss, since the keratorefractive procedure may have caused some prior loss. 4.3.3.2 Intraoperative Autorefractor/ Retinoscopy Large refractive surprises can be avoided by intraoperative retinoscopy or hand-held autorefractors. These refractions should not be relied upon, however, for fine tuning the intraocular lens power, since there are many factors at surgery that may change in the
postoperative period. Factors such as the pressure from the lid speculum,axial position of the intraocular lens, intraocular pressure, etc. may cause the intraoperative refraction to be different than the final stabilized postoperative refraction. If the intraoperative refraction is within 2 D of the target refraction, no lens exchanges should be considered unless intraoperative keratometry can also be performed. 4.3.4 Postoperative Evaluation 4.3.4.1 Refraction on the First Postoperative Day On the first postoperative day following cataract surgery, patients who previously have had RK usually have a hyperopic shift, similar to the first postoperative day following their RK. This phenomenon is primarily due to the transient corneal edema that usually exaggerates the RK effect. These patients also exhibit the same daily fluctuations during the early postoperative period after their cataract surgery as they did after the RK. Usually this daily shift is in a myopic direction during the day due to the regression of corneal edema after awakening in the morning [22]. Because the refractive changes are expected and vary significantly among patients, no lens exchange should be contemplated until after the first postoperative week or until after the refraction has stabilized, whichever is longer. Very few results of cataract surgery following PRK and LASIK are available. In the few cases that have been performed, the hyperopic shift on the first day and daily fluctuations appear to be much less, similar to the early postoperative period following these procedures.In most cases the stability of the cornea makes these cases no different than patients who have not had keratorefractive surgery. Chapter 4 Intraocular <strong>Lens</strong> Power Calculations 31 4.3.4.2 Long-term Results Long-term results of cataract surgery following RK are very good. The long-term hyperopic shifts and development of against-therule astigmatism over time following cataract surgery should be the same as in the longterm studies following RK. The problems with glare and starburst patterns are usually minimal because the patients have had to adjust to these unwanted optical images following the initial RK. If the patient’s primary complaint before cataract surgery is glare and starbursts, it should be made clear to him that only the glare due to the cataract will be removed by surgery, and the symptoms that are due to the RK will remain unchanged. Long-term results following PRK and LASIK are non-existent. Since there are no signs of hyperopic drifts or development of against-the-rule astigmatism in the 5-year studies following PRK, one would not expect to see these changes. However, the early studies following RK did not suggest any of these long-term changes either. Only time will tell whether central haze, irregular astigmatism, etc. will be problems that develop in the future. 4.4 Patients with Previous Scleral Buckling and/or Silicone in the Vitreous Cavity Patients who have undergone scleral buckling usually have an increase in their axial length by an average of 0.8 mm, which usually results in an approximate 2.4 diopter myopic shift. This value may range from 0 to 2.0 mm, depending on the location and tension on the encircling band. If no silicone oil has been placed in the vitreous cavity, measuring the axial length is no different than in patients with high myopia. Choosing the target postoperative refraction is also no different than for the normal patient, although
Page 2 and 3: Refractive Lens Surgery I. H. Fine
Page 4 and 5: Editors I. Howard Fine, MD Mark Pac
Page 6 and 7: 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 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 58 and 59: 44 D.D. Koch · L.Wang Fig. 5.4. Nu
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 94 and 95:
82 M. Packer · I.H. Fine · R.S. H
Page 96 and 97:
84 M. Packer · I.H. Fine · R.S. H
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
Page 108 and 109:
10. Dell SJ (2004) Objective eviden
Page 110 and 111:
100 N.X. Nguyen · A. Langenbucher
Page 112 and 113:
Page 114 and 115:
Page 116 and 117:
Page 118 and 119:
Page 120 and 121:
Page 122 and 123:
12 CORE MESSAGES Synchrony IOL H. B
Page 124 and 125:
Fig. 12.1. The single-piece silicon
Page 126 and 127:
12.5 Clinical Results Clinical tria
Page 128 and 129:
Fig. 12.6. Retroillumination photog
Page 130 and 131:
References 1. Fisher RF (1973) Pres
Page 132 and 133:
124 F.M. Sarfarazi 13.1 The Nature
Page 134 and 135:
126 F.M. Sarfarazi Fig. 13.4. Lens
Page 136 and 137:
128 F.M. Sarfarazi Fig. 13.5. Mecha
Page 138 and 139:
130 F.M. Sarfarazi Fig. 13.9. Secon
Page 140 and 141:
132 F.M. Sarfarazi Fig. 13.14. Sche
Page 142 and 143:
134 F.M. Sarfarazi Fig. 13.18. Work
Page 144 and 145:
136 F.M. Sarfarazi References 1. Ma
Page 146 and 147:
138 A. Mirshahi · E.Terzi · T. Ko
Page 148 and 149:
Page 150 and 151:
Page 152 and 153:
15 The Tecnis Multifocal IOL Mark P
Page 154 and 155:
Fig. 15.1. The Alcon AcrySof multif
Page 156 and 157:
Fig. 15.4. Multifocal vs. monofocal
Page 158 and 159:
16 Blue-Light-Filtering Intraocular
Page 160 and 161:
Fig. 16.2. Cultured human RPE cells
Page 162 and 163:
tion to benefiting from less exposu
Page 164 and 165:
16.7 Blue-Light-Filtering IOLs and
Page 166 and 167:
15. Marshall J, Mellerio J, Palmer
Page 168 and 169:
17 CORE MESSAGES The Light-Adjustab
Page 170 and 171:
Fig. 17.2 a-c. Cross-sectional sche
Page 172 and 173:
17.4 Animal Studies Dr. Nick Mamali
Page 174 and 175:
Fig. 17.8. A laser interferogram (l
Page 176 and 177:
enhanced visual function that remai
Page 178 and 179:
13. Mather R, Karenchak LM, Romanow
Page 180 and 181:
174 S. Norrby Fig. 18.1. Small cale
Page 182 and 183:
176 S. Norrby Fig. 18.3. Scheimpflu
Page 184 and 185:
178 S. Norrby Fig. 18.4. Schematic
Page 186 and 187:
180 S. Norrby there was fibrin form
Page 188 and 189:
182 S. Norrby material had a Young
Page 190 and 191:
184 S. Norrby Koopmans et al. [28]
Page 192 and 193:
186 S. Norrby 40. De Groot JH, Zuru
Page 194 and 195:
188 L. Nordan · M. Morris regular
Page 196 and 197:
190 L. Nordan · M. Morris produce
Page 198 and 199:
20 CORE MESSAGES Bimanual Ultrasoun
Page 200 and 201:
for an irrigating manipulator or ch
Page 202 and 203:
5. Tsuneoka H, Shiba T, Takahashi Y
Page 204 and 205:
200 J.L. Alio · A. Galal · J.-L.R
Page 206 and 207:
Page 208 and 209:
Page 210 and 211:
Page 212 and 213:
22 CORE MESSAGES The Infiniti Visio
Page 214 and 215:
Fig. 22.3. The AquaLase handpiece u
Page 216 and 217:
23 CORE MESSAGES The Millennium Ros
Page 218 and 219:
Fig. 23.1. Bausch & Lomb’s new cu
Page 220 and 221:
Fig. 23.2. Advanced flow system car
Page 222 and 223:
Fig. 23.5. Pulse or burst mode with
Page 224 and 225:
24 CORE MESSAGES The Staar Sonic Wa
Page 226 and 227:
Fig. 24.2. The tip undergoes compre
Page 228 and 229:
the sonic tip moves back and forth
Page 230 and 231:
25 CORE MESSAGES AMO Sovereign with
Page 232 and 233:
Fig. 25.3. Schematic diagram of cav
Page 234 and 235:
the Sovereign Compact (see Fig. 25.
Page 236 and 237:
234 M. Packer · R.S. Hoffman · I.
Page 238 and 239:
27 Conclusion: The Future of Refrac
Page 240 and 241:
240 Subject Index Contrast sensitiv
Page 242 and 243:
242 Subject Index P Pachymetry 53,
show all

Refractive Lens Surgery

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?