Ординатура / Офтальмология / Английские материалы / LASIK and Beyond LASIK Wavefront Analysis and Customized Ablation_Boyd_2001

How to Order a Custom-Made Lens for Each Patient

Barraquer and Uxo send the manufacturer (Corneal WK) the following clinical information to obtain a lens which is custom made for each patient. This is necessary because of the very high power lenses needed.

1)Visual acuity without refractive correction.

2)Visual acuity with spectacle or contact lens correction;

3)Spectacle prescription and vertex distance.

4)Refraction with the autorefractometer.

5)Axial length.

6)Depth of the anterior chamber.

7)Keratometer readings.

8)Corneal topography.

Where Is the Barraquer Lens

Available

This lens is available through the following company: CORNEAL, oupe W.K*.; Parc d’ Activities Pré Mairie; B.P. 13; F-74371 PRINGY Cedex, France - FAX Nº: 33-04 50 27 26 89.

Figure 44-27: Side View of Implantation Maneuver of Barraquer’s Pre-Crytalline Lens

The implantation technique shown in Figs. 44-25 and 44-26 as surgeon’s view is presented here as a side view. It provides a graphic demonstration of how the lens glides into the very narrow space between the postgerior surface of the iris and the anterior surface of the patient’s own crystalline lens. (1) Represents the lens optics, (H) the haptics being inserted to rest in the sulcus (red arrow). (2) Shows the lens finally in place with the two blue arrows pointing toward the lens. (L) is the patient’s own crystalline lens. The green arrow demonstratges how the other haptic is inserted in the sulcus. (After Boyd´s

"Atlas of Refractive Surgery").

Figure 44-28: Barraquer’s Pre-Crystalline Posterior

Chamber IOL Implantation Technique - Final Configuration

This oblique cross section view shows the final threedimensional configuration of the pre-crystalline IOL in place. Note that the incision is closed with 9 or 10 interrupted corneoscleral sutures. A section of the IOL is shown in cross section (X) to see its relationship to the anterior capsule (A) of the natural crystalline lens. The IOL does not come into contact with the natural lens except for two small areas near the periphery (arrows). Haptics (14mm) are properly placed in the ciliary sulcus (S). Note YAG laser peripheral iridotomy (B). (After

Boyd´s "Atlas of Refractive Surgery").

Contents

Section 1

Section 2

Section 3

Section 4

Section 5

Section 6

Section 7

Subjects Index

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Contents

Section 1

Section 2

Section 3

Section 4

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Section 6

Section 7

Subjects Index

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This is an ingenious development originally known as the “Implantable Contact Lens” ( ICL) or foldable, soft pre-crystalline lens as pioneered by

Ricardo Guimãraes, M.D., in Brazil and Roberto Zaldivar, M.D., in Argentina. It is manufactured by the Swiss company, Staar Surgical. The original name of ICL was chosen to differentiate this lens from the posterior chamber intraocular lens (PCIOL). The critical feature of this lens is the new material of which it is made: a mixture of hydrogel and collagen polymer, which is called a collamer. It is very permeable and hydrophilic. The ICL is placed between the iris and the natural crystalline lens.

It is soft and very thin - only 100 microns in thickness, as compared to the 1 mm required for a 30 diopter power silicone lens. Although this lens is fitted in the posterior chamber, it does not lie on the surface of the crystalline lens. A space that varies between 100 and 150 microns exists between the capsule of the crystalline lens and the new ICL

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Subjects Index

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Chapter 44

Figure 44-31 C: Insertion Technique of the Foldable Posterior Chamber Phakic IOL - Cross Section View - Step 2

The plunger (P) continues to push (arrow) the IOL (C) out of the injector until the entire unfolded lens rests on the iris in the anterior chamber. The injector is removed from the incision. (After Boyd´s "Atlas of Refractive Surgery").

Figure 44-31 B: Insertion Technique of the Foldable Posterior Chamber Phakic Lens (ICL) - Cross Section View Step 2

With a viscoelastic present, a foldable posterior chamber phakic IOL (C) is placed into the anterior chamber via a special injector placed through a small corneal incision. A plunger (P) within the injector pushes the IOL out into the anterior chamber with the distal haptic directed toward the angle

(A). Some surgeons add a piece of microsponge to act as a softer pusher. Note the position of the IOL (C), as it unfolds, in relation to the natural lens (L). (After Boyd´s "Atlas of Refractive Surgery").

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Subjects Index

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Implantation Technique

One week previous to the surgery, two peripheral iridectomies are performed using the YAG laser, to avoid pupil blockage (Fig. 44-30). They are done one week before surgery because they are difficult to do intraoperatively when the pupil is dilated. The iridectomies are performed very close to 12 o’clock.

Implanting the lens requires a 3 mm temporal clear corneal incision (Fig. 44-30). The lens is so thin that it can be folded and inserted through this very small incision (Fig. 44-31A). The surgical

technique must be very smooth. A temporal corneal tunnel incision is made followed by two paracentesis. Then the chamber is filled with viscoelastic. The pupil must be very dilated. The lens must be folded in a special cartridge and injected very slowly inside the eye (Figs. 44-30, 44-31 A-C).

The recently redesigned lens injector has a sponge attached to the plunger that facilitates insertion, prevents air bubbles and allows better lens positioning. Insert the plunger and release the lens. Place the haptics beneath the iris with a spatula without applying any pressure to the optic (Figs. 44-32, 44-33).

Figure 44-32B: Insertion Technique of the Foldable

Posterior Chamber Phakic Lens (ICL) - Cross

Section View - Step 3

A special spatula (S) is inserted through one of the prepared side ports and engages the distal footplate of the IOL. The spatula (white arrow) pushes the distal footplates directly behind the iris (green arrow) and into the ciliary sulcus. (After Boyd´s

"Atlas of Refractive Surgery").

Figure 44-33: Insertion Technique of the

Foldable Posterior Chamber Phakic Lens (ICL)

- Side View - Step 4

The special spatula (S) then engages the proximal footplates of the IOL. The spatula (white arrow) pushes the proximal footplates directly behind the iris (green arrow) and into the ciliary sulcus. (After Boyd´s "Atlas of Refractive Surgery").

As the lens is injected, it slides on the surface of the crystalline lens because the iris is very dilated. The lens unfolds (Fig. 44-31A). When the lens is floating on the viscoelastic on the surface of the crystalline lens, the surgeon must introduce the four small haptics or footplates behind the iris and in the sulcus (Fig. 44-32 A, B). When the haptics are in place behind the iris (Fig. 44-33), the pupil is constricted, leaving the lens lying in the posterior chamber, and the viscoelastic is removed (Fig. 4434). The pupil is treated with acetylcholine. Zaldivar uses Miochol.

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Figure 44-34: Conceptual Cross Section of All Stages for Implantation of a Foldable Posterior Chamber Phakic Lens (ICL)

This conceptual cross section shows the insertion and unfolding of the (ICL) compared to the final configuration of the ICL in position behind the iris and in front of the crystalline lens. (1) The plunger (P) inside the inserter pushes the distal haptics of the ICL into the anterior chamber (blue arrows) while unfolding as shown. (2) In separate maneuvers, the haptics are then placed (red arrows) into the posterior chamber behind the iris and into the ciliary sulcus. The iris will then be constricted. The inset shows a surgeon’s view of this final configuration.

This illustration is a section of the eye taken from 3 to 9 o’clock, as the ICL is inserted through the temporal approach. (After Boyd´s "Atlas of Refractive Surgery").

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Complications

In a group of 160 human eyes (patients), operated by Guimarães there have been no complications from the ICL. In fact, he has observed that this patient group has been the most satisfied of any group of the refractive surgery patients he has had. He has patients who have an ICL in one eye and have undergone a LASIK procedure in the other. The patients themselves can compare the results. Even though the correction using the ICL was much higher, patients said they had better vision in the eye

with the ICL than the one on which the corneal

refractive procedure was performed. Guimarães con-

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siders that the ICL is reliable because it is reversible and offers predictability and high quality.

Zaldivar began to work with this lens in 1993. After 4 years of follow-up, no patient from the original group has developed cataracts. At first Zaldivar was concerned about the possible development of pigment dispersion glaucoma because of the contact of the iris with the lens, but the first lenses of this type were redesigned and improved. This new lens is so thin that almost no pigment movement in the eye occurs.

Chapter 44

BIBLIOGRAPHY

Baikoff, G., "Phakic Anterior Chamber Intraocular Lenses", International Ophthalmology Clinics, Vol. 31:1, Winter, 1991.

Barraquer, Joaquin, "Pre-Crystalline Posterior Chamber Phakic Intraocular Lenses for High Myopia",

Highlights of Ophthalmology Journal, Nº 2,1998;1624.

Guimaraes, R., "The Implantable Contact Lens",

Highlights of Ophthalmology Journal, Nº 4,1998;3942.

Landerz, M., Worst, JG., Siertsema, JV., Van Riji G., "Correction of High Myopia with the Worst Myopia Claw Intraocular Lens", Journal of Refractive Surgery, 11:1995.

Worst, J., "The Artisan IOL for the Correction of

Refractive Errors", Highlights of Ophthalmology

Journal, Nº 3,1999.

Zaldivar, Roberto, "The Implantable Contact Lens", Highlights of Ophthalmology Journal, Nº 4,1998;39-42.

Benjamin F. Boyd, M.D., F.A.C.S.

Editor in Chief

Highlights of Ophthalmology

Box 6-3299 -El Dorado

Panama, Rep. of Panama

Fax= (507) 317-0156

E-mail: kmejia@hophthal.com

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Subjects Index

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Among the mysteries still to be resolved about LASIK is what is the upper range of its practical value. There is certainly a point that will vary from patient to patient, but still be consistent among a large population, at which the postoperative optics of LASIK begin to deteriorate and at which the potential complications outweigh the practical benefits when compared to other methods of treating myopia. When LASIK first became practical, there were attempts to correct as much as 25 diopters of myopia. This proved to be quite unsatisfactory, and so the range of attempted LASIK correction has to a large degree moderated. There is general consensus that LASIK up to 8 diopters is quite good and that LASIK much above 12 diopters is not. It remains necessary to attempt to demonstrate whether LASIK in the range in between 8 and 12 diopters is as good as or better than other ways of correcting high myopia.

There are only a few alternatives to LASIK in this refractive group. One adequate alternative is implanting a phakic intraocular lens. Another less attractive alternative is lensectomy with lens implantation. Lensectomy is certainly quick and efficient, with very rapid visual recovery, measured usually in minutes or hours. However, the risk to the eye in terms of retinal complications among high myopes may be excessive, considering the elective nature of the full procedure.

The major options, then, are either LASIK or phakic intraocular lens.

One very good phakic intraocular lens is the Ophtec Artisan™ lens, from Holland. This lens is