Ординатура / Офтальмология / Английские материалы / Visual Prosthesis and Ophthalmic Devices New Hope in Sight_Rizzo, Tombran-Tink, Barnstable_2007
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The Use of Intracorneal Ring Segments for Keratoconus |
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Fig. 12. Example of a preoperative topography of a keratoconus eye.
Fig. 13. Same eye of Fig. 10, after 11 mo of Ferrara’s ring segments implantation under a corneal flap.
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Fig. 14. Ring segment extrusion 5 mo after implantation.
Fig. 15. Disciform keratitis adjacent to the segment, 7 mo after surgery.
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Fig. 16. Bacterial keratitis after ring extrusion.
3.Ring segment centration based on central corneal reflex;
4.Correct selection of ring segment position in the flat corneal meridian;
5.Selection of asymmetric rings based on corneal topography;
6.Simultaneous 160 m corneal flap if corneal thickness is at least 500 m in its thinnest point; and
7.Avoid implanting the ring segments in advanced keratoconus or if there is already a corneal opacity.
The experience suggests that FICRS have a definite place in the treatment of keratoconus, especially in those patients that are contact lens intolerant and are candidate for PK for visual improvement. This procedure has been proved to be successful for several keratoconus patients that are in the waiting list for a PK, being an extraocular fast surgery with topical anesthesia and having a very low ring rejection rate. Besides improving BCSVA, it will be possible to avoid or delay PK in many keratoconus eyes (76.5% of cases in author’s personal experience).
In conclusion, FICRS implantation has the advantage of being reversible, adjustable, safe, and a low cost surgery, with reasonable predictable results that can recover BCSVA in several cases of keratoconus patients. Another advantage is that it does not interfere with a future PK if necessary, because it is placed inside the diameter of a PK. However, the long-term stability of these results is not known. Further clinical and experimental studies with more patients and longer follow-up are needed to improve accuracy and stability of FICRS results.
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REFERENCES
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Index |
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Index
Ahmed glaucoma valve, 178, 185, 193 AMD, 55
Aniseikonia, 42
Anterior chamber lenses, 240 Antimetabolites, 184 Antimitotic, 194
Aqueous humor dynamics, 174 Artificial silicon retina (ASR), 38 Artisan toric lens, 221 Automatic gain control, 138 Baerveldt tubes, 193 Biocompatibility, 59, 82, 87, 100 Biohybrid retinal implant, 20 Bleb fibrosis, 201
Boston Retinal Implant Project, 80 Carbon nanotube, 129
Cataract, 245
Cone terminal attenuation, 138 Contrast adaptation, 151 Contrast gain control, 143, 154 Contrast resolution, 9
Cornea, Intrastromal rings, 214 Cortical visual prostheses, 136 Crowding effect, 21 Cycloplegia, 198
Data integrator, 99 Data telemetry, 58, 62 Data transmission, 82
Diabetic retinopathy, 159 Diplopia, 200
Dual-band telemetry, 61, Dynamic perception, 6 Eccentric locations, 21 Edge detection, 58
Electrical evoked potential, 114, 166 Electrical stimulation, 90, 111 Electrocatalytic interface, 163 Electroretinography, 40 Enhancement, 58
Epiretinal implant, 19 Epiretinal placement, 124
Expanded polytetrafluorethylene, 185
External image processing, 58 External video camera, 56 Extraocular retinal prosthesis, 164 Ferrara’s ring segments (FICRS), 260 Fibrosis, 181, 184
Giant papillary conjunctivitis, 241 Glaucoma, 159, 173
drainage devices, 173 filtration surgery, 176 neovascular, 196 pediatric, 196
pump implant, 178 Glial cell proliferation, 111 Graft rejections, 227 Hemorrhage, 200
Horizontally drifting text, 24 Human clinical trial, 39 Hydroxylapatite, 185 Hypertensive phase, 203 Hypotony, 184, 199
Implantable miniature telescope, 252 Implantation, 96
Infection, 197
Intracorneal ring segments, 259 Intracortical microstimulation, 161 Intraocular pressure, 173
Involuntary reflexive eye-movements, 26 Iridium oxide, 59, 83
Iris atrophy, 245 Iris-fixated lenses, 242 Joseph implant, 178 Keratoconus, 259 Keratoplasty, 221 Krupin slit valve, 178 Lamina cribrosa, 174 LASIK, 221
Light adaptation, 151 Load-shift keying, 64
Luminance adaptation curves, 152 Macular degeneration, 1
Macular degeneration, age-related, AMD, 55, 107, 159, 251
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Index |
Marfan’s syndrome, 247 Mechanical stabilization, 96 Microelectrode array (MEA), 108 Microphotodiode-array chip, 38 Molteno implant, 177
Molteno tubes, 193 Myopia, 239
Narrow-field amacrine cell, 145 Nd:YAG laser hyloidotomy, 198 Neuro-morphic chip, 75 Neuronal degeneration, 111 Neurotrophic factor, 51 Nine-Sector Test, 44
Object recognition, 6 Oculomotor system, 26 Optic nerve ischaemia, 159 Optic nerve, 80, 174 Parylene, 59, 83
Pellucid marginal corneal degeneration, 211
Penetrating keratoplasty, 195 Perceptual thresholds, 88 Phakic intraocular lenses, 239
Phosphene, 5, 37, 90, 95 108, 136, 165 Photoreceptor cell transplantation, 2 Phototransistors, 146
Pixelized images, 21 Pixelized vision system, 18, Platinum, 59, 83
Polydimethylsiloxane, 59, 127, 181 Polyimide electrode array, 108 Polyimide, 59, 108, 125 Polymethylmethacrylate, 185 Posterior chamber lenses, 243 Power telemetry, 58, 61
Prosthesis
cochlear, 4, 16, 67, 75, 161 retinal, 2,5, 29, 111,136 subretinal, 124
wireless, 82 visual, 72
visual cortex, 160 Radio frequency, 57 Radius of curvature, 121
Rapid serial visual presentation, 24 Reading rates, 17
Reading, 15
Retina
amacrine cell, wide-field, 143 bipolar cell, 143
bipolar terminal, 145 degenerations, 1, 159 ganglion cell, 73, 116, 174 ganglion cell responses, 145 inner, 141
outer, 138 Retinal fatigue, 49 Retinal stimulation, 9
Retinitis pigmentosa, 1, 37, 55, 107 Reverse data telemetry, 64
RGCs, 84
Schocket tube implant, 178 Scleral erosion, 200
Signal filter integrator, 99 Silicon retina, 137, 148 Silicon retinal tack, 111 Silicone, 181
Spatial resolution, 6 Spatiotemporal filtering, 148 Spike density coding, 10 Steroids, 242
Stimulating electrodes, 59 Stimulation current-field, 7 Stimulator chip, 66, 82 Stimulator, 58
Stimulus polarity, 162 Stimulus pulse trains, 11
Suprachoroidal hemorrhage, 199 Supra-choroidal space, 77, Surface electrode array, 161 Susanna drainage device, 178 Temporal contrast, 144 Titanium nitride, 59
Trabecular meshwork, 175 Trabeculectomy, 176 Trauma, 159
Trophic factors, 174 Urrets-Zavalia syndrome, 243 Uveitic glaucoma, 196 Visual acuity, 40, 197, 224 Visual evoked potential, 114 Visual field testing, 40
Visual function improvements, 50 Visuo-motor coordination, 15