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

Figure 44-12: Artisan IOL Surgical Implantation Technique - Final Configuration

This illustration shows the properly placed and centered Artisan IOL. The wound is then carefully closed and all viscoelastic is meticulously removed while maintaining the anterior chamber depth. Note the properly trapped iris (A) within the haptic slots. Peripheral iridotomy (I). (After Boyd´s "Atlas of Refractive Surgery").

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Subjects Index

Postoperative Complications

What if the Implant Needs to be Repositioned, Removed, or Exchanged?

Should the lens not be centered, a loop can be detached and reattached with some ease. Detachment only requires that one side of the loop be depressed while the lens is stabilized by forceps. In the rare event that a loop of the IOL is found not to be securely attached to the iris, it can be reattached through stab incisions, repeating the maneuvers illustrated in Figs. 44-4 - 44-10. Should an IOL need to be removed (for power exchange, for example),

detachment of both tips is done as described above, under high density viscoelastic. Then enlarge the wound, slide the lens out, and replace it. Be gentle with the iris, and do not touch the corneal endothelium.

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Availability

The lenses may be obtained from Ophtec, Schweitzerlaan 15, 9728 NR Groningen, Holland. They are distributed for the clinical investigation under FDA regulation in the US by Ophtec USA, Inc., 6421 Congress Ave., Suite 112, Boca Raton, FL 33487.

PHAKIC I OL's SURGICAL MANAGEMENT OF HIGH MYOPIA

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Maria Clara Arbelaez, M.D., considers the Nu-Vita lens her technique of choice for the correction of high myopia, from -8.00 D and up, because the results are predictable and safe, and the lens provides good quality of vision with improved contrast sensitivity. She emphasizes that a miotic must be used and a small iridectomy be performed, as needed when implanting all anterior chamber lenses. These are very delicate lenses and the haptics can be easily broken. Their cost is around US$700.00.

Calculation of Size

This is a most important measure to take with the use of the Nu Vita lens. Meticulous calculation of

Figure 44-14: Insertion Technique of

the Nu-Vita Anterior Phakic Chamber

Intraocular Lens - Step 1

A temporal 5.5 mm self-sealing corneal incision is made. A forceps (F) grasps the optic of the intraocular lens (L) and inserts it into the anterior chamber as shown. The distal footplate must be snaked through the incision. (After Boyd´s "Atlas of Refractive Surgery").

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Subjects Index

Presence of Large Astigmatism and

High Myopia

In these patients, Arbelaez inserts the NuVita lens first and later follows with LASIK in a second stage to correct the astigmatism.

Figure 44-16: Insertion Technique of the

Nu-Vita Anterior Phakic Chamber

Intraocular Lens - Step 3

A check of the position of the distal footplates is made with a gonio prism. This is done to check that there is no tucking of the iris peripherally. Note that the footplates (H) are indeed in the correct location in the angle with no iris tuck. The proximal fooplates (S) are still outside the incision at this stage.

(After Boyd´s "Atlas of Refractive Surgery").

Figure 44-15: Insertion Technique of the

Nu-Vita Anterior Phakic Chamber

Intraocular Lens - Step 2

The forceps retain a grasp on the optic and the IOL is placed into the anterior chamber (arrow). The forceps (F) are repositioned to grasp the elbow (H) of the proximal haptic and the IOL is continued into the anterior chamber (arrow). This technique avoids the insertion of an instrument into a phakic eye all the way into the pupillary area. The distal footplates are directed toward the angle. The proximal haptic is then placed in the incision, but the proximal footplates remain outside the eye. (After Boyd´s "Atlas of Refractive Surgery").

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Subjects Index

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Contents

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Section 7

Subjects Index

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THE POSTERIOR CHAMBER PLATE LENSES

THE BARRAQUER PRECRYSTALLINE LENS

Barraquer has implanted these lenses in 183 eyes since 1995 with the valuable collaboration of Dr. Mercedes Uxo. A thorough and meticulous follow-up and analysis of each case has been performed. Fig. 44-20 shows how this lens fits into the pre-crystalline space and corrects high myopia.

In the search to correct high myopia above -8.00 and -9.00 D with methods other than excimer laser (LASIK) Professor Joaquin Barraquer, M.D., F.A.C.S., developed in 1995 an ingenious technique for the implantation of an ultra delicate PMMA phakic lens between the posterior surface of the iris and the anterior surface of the patient’s own crystalline lens (Fig. 44-27). This is the pre-crystal- line lens to correct high myopia, starting with -8.00 D and higher as advised by Professor Barraquer.

The reasons for avoiding LASIK in high myopia have already been outlined: lower quality of vision and contrast sensitivity than with phakic IOL’s, in addition to the other occasional problems inherent to the LASIK technique.

Figure 44-20: Optical System of

Highly Myopic Patient with Pre-

Crystalline Posterior Chamber IOL

Versus Human Lens Only

(A) The top figure shows refraction in high myopia with the focal point of the image (F) anterior to the retina. The image is blurred. (B) The lower figure shows the post-op refraction with pre-crystalline lens in place, with the image focusing (F’) on the retina.

(After Boyd´s "Atlas of Refractive Surgery").

myopia based on this pre-crystalline posterior chamber IOL implant is important because of his widely respected reputation and credibility.

Description of the Barraquer Lens

The lens has evolved through three (3) gen- eration-designs. The third generation lens has successfully overcome initial problems that presented with the first two (2) generations. The majority of the Barraquer series has been performed with the third generation lenses which began in June 1997 (120 eyes from a total of 183.)

The lens is manufactured by Corneal W.K. in France. It is fixated in the sulcus (Fig. 44-28). It has an optical diameter of 6 mm. The length of the “body” of the lens is 9 mm. It has flexible haptics up to 14 mm in diameter (Fig. 44-21) to allow adequate sulcus fixation (Figs. 44-26 - 44-27). The “body” of the lens, the 6 mm diameter optic, has two 1.5 mm plates which are necessary to avoid capture of the lens by the iris when the pupil dilates. The iris glides smoothly over the plates and the optic. The periphery of the IOL remains in front of the crystalline lens and behind the iris (Figs. 44-27 - 44-28).

Figure 44-23: Barraquer’s Pre-Crystalline

Posterior Chamber IOL Implantation

Technique - Step 2

A viscoelastic substance is injected through the paracentesis via a cannula

(C) to fill the anterior chamber. This will maintain the chamber depth and increase dilation of the pupil. At one end of the nonpenetrating limbal incision, a horizontal beveled incision is made with a disposable keratome knife (D) shown here at 2 o’clock. This will begin the second plane of the two plane incision. Fixation forceps (F). (After

Boyd´s "Atlas of Refractive Surgery").

Figure 44-22: Barraquer’s Pre-

Crystalline Posterior Chamber IOL

Implantation Technique - Step 1

A non-penetrating perpendicular incision is performed 1mm behind the limbus with a diamond blade knife (K). The incision is shown here beginning at 2 o’clock while the blade (K) is shown at 10 o’clock. This incision is extended superiorly from 2 to 10 o’clock (arrow) for a length of 8mm. This is the first plane of the two plane incision. Fixation forceps (F). A paracentesis at the limbus is made temporally as shown with a stiletto knife (S). Note: YAG laser peripheral iridotomy (B) is performed 15 days before the operation to facilitate aqueous circulation from the posterior to the anterior chamber and avoid relative pupillary block and possible angle-closure glaucoma. (After Boyd´s "Atlas of Refractive Surgery").

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Subjects Index

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Chapter 44

Figure 44-24: Barraquer’s Pre-Crystalline Posterior Chamber IOL Implantation Technique - Step 3

(A) The two plane horizontal beveled incision made with the keratome (D -figure 6) is completed (red arrow) with Jose Barraquer’s scissors (S) in the deep layers of the groove. (B) Viscoelastic is introduced with a cannula behind the iris, in front of the crystalline lens, toward the ciliary sulcus at 6 o’clock (1-blue arrow) and then (2- blue arrow) at 2 o’clock. This will facilitate safer and easier introduction of the flexible haptics into the sulcus. (After Boyd´s "Atlas of Refractive Surgery").

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Subjects Index

Inserting an intraocular foreign body between the posterior surface of the iris and the anterior surface of the crystalline lens certainly requires a highly skilled surgeon to prevent harming these delicate tissues. Perhaps, with time, more experience and a great deal of teaching and training of other surgeons, this technique might prove to be an important positive step in the quest for a method that is certainly much less costly than the present Excimer procedures and would be available to more surgeons and more patients.

1) Two weeks before the lens implantation

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two YAG laser iridotomies are performed (Fig. 4429A).

2)Deep general anesthesia. This has been Professor Barraquer’s preferred method for many years.

3)Intravenous Mannitol, in order to obtain maximum hypotony.

4)Fornix based conjunctival flap which is provisionally sutured to the sterile drape, covering the lid margin to avoid contact of instruments and the IOL with the eyelashes.

Figure 44-26: Barraquer’s Pre-Crystalline Posterior Chamber IOL Implantation Technique - Step 5

Once the pre-crystalline lens is inside the eye, the Sinsky hook (H) is placed through the plate manipulation hole and pushes the lens away from the incision (red arrow). At the same time, the blunt-tipped forceps (F) grasps the upper haptic at the special haptic manipulation hole. The haptic is compressed and directed behind the iris and into the ciliary sulcus (blue arrow). The Sinsky hook (H) is used to depress the optic slightly during this maneuver to assist in directing the haptic behind the iris. (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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