Pigment vacuum iridectomy for phakicrefractive lens implantation

Kenneth J. Hoffer, MD

ABSTRACT

I present a technique designed to ensure an atraumatic patent basal iridectomy for phakicrefractive lens implantation. The technique divides the iridectomy procedure into 2 steps.First, the stromal layer is removed by surgical excision. Then, the pigment layer is removedby gentle vacuum aspiration with a 25 gauge cannula. Atraumatic, small, basal peripheraliridectomies that are functional and cosmetically pleasing have been performed in 12 eyes.There were no cases of large amounts of pigment debris deposited in the trabecularmeshwork as checked by gonioscopy. Pigment vacuum iridectomy may be a reliableprocedure to ensure a proper basal iridectomy in any type of anterior segment eye surgery.J Cataract Refract Surg 2001; 27:1166–1168 © 2001 ASCRS and ESCRS

The peripheral iridectomy, the bane of many eyesurgeons, seemed to become unnecessary in the age

of modern posterior chamber intraocular lens (IOL) im-plantation. Gills first recommended its elimination inuneventful cases more than 10 years ago. Because of this,many surgeons have become rusty in the finesse andtechnique of performing a “perfect” surgical iridectomy.

Peripheral iridectomies are still necessary in somecases and mandatory in cases of anterior chamber IOLimplantation. An iridectomy is also mandatory in pha-kic IOL implantation in refractive surgery, whether thelens is an anterior chamber, iris-supported, or posteriorchamber model. Surgeons have the option of perform-ing 1 or 2 peripheral iridotomies using a neodymium:YAG (Nd:YAG) or argon laser or to create an iridectomysurgically at the time of phakic IOL implantation.

The advantage of an Nd:YAG iridectomy is that itcan be performed in an office setting, allowing the sur-geon to ensure its patency before implanting an IOL.The disadvantages are as follows:

1. It requires 2 procedures (iridotomy and phakic IOLimplantation).

2. On rare occasions, it can be painful if retrobulbaranesthesia is not used.

3. It becomes unnecessary if IOL implantation is neverperformed.

4. It can be difficult to ensure its patency.5. It can be too small and, on rare occasions, may reseal.6. Dense pigment particles are deposited in the angle

meshwork (potential blockage).7. It is more difficult to make a truly basal opening.

The advantages of a surgical iridectomy are the op-posite of those of the Nd:YAG iridectomy, while thedisadvantages are as follows:

1. Intraocular bleeding, including 8-ball hemorrhage,can occur.

2. There is a risk of injury to the crystalline lens, causingcataract.

3. If the iridectomy is too large, it may cause optical“second-image” glare.

4. It is technically difficult to make a small, truly basalperipheral iridectomy.

5. It is technically difficult to cut both the stromal andpigment layers in 1 maneuver.

Accepted for publication February 19, 2001.

Reprint requests to Kenneth J. Hoffer, MD, St. Mary’s Eye Center,1441 Broadway, Santa Monica, California 90404, USA. E-mail:KHofferMD@aol.com.

© 2001 ASCRS and ESCRS 0886-3350/01/$–see front matterPublished by Elsevier Science Inc. PII S0886-3350(01)00845-8

Figure 1. (Hoffer) A Zaldivar iridectomy forceps and scissors areused to excise basal iris stroma through a 1.5 mm limbal incision.

Figure 2. (Hoffer) Viscoelastic material is injected over the iridec-tomy site covering the pigment layer.

Figure 3. (Hoffer) A: The pigment layer is aspirated with a 25 gauge cannula on a BSS syringe. B: The pigment layer is further aspirated. Notered reflex. C: The remaining pigment layer is aspirated.

Figure 4. (Hoffer) The pigment particulate matter is irrigated ontothe conjunctiva.

Figure 5. (Hoffer) The final status of the phakic eye after phackicIOL implantation and surgical pigment vacuum iridectomy.

TECHNIQUES: HOFFER

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6. The lens may be damaged when the surgeon at-tempts to open the remaining pigment layer.

I developed a simple method of performing a surgi-cal iridectomy that eliminates many of its disadvantages.

Surgical TechniqueTo best obtain access to the basal iris, rather than

making a shelved incision, the surgeon should make theincision in the corneal limbus in an approach that isperpendicular to the iris plane. To be sure there isenough room for the instruments to function, theincision should be at least 1.0 mm wide, but no largerthan 1.5 mm so that the perpendicular cut will beself-sealing.

Because 2 layers of the iris (stroma and pigmentlayer) are easily separated, deep forceful purchase of theiris with the forceps is required to pull both layersthrough the incision in 1 maneuver, similar to grabbingthe bedspread and the sheet without pressing on themattress. With this technique, the initial step ignores thepigment layer, allowing the surgeon to concentrate ongrasping only the iris stroma for traction through theincision and excision. Thus, excess force on the crystal-line lens or zonular fibers is not necessary. Because thepigment layer is ignored, the surgeon is better able tofocus on pulling out and excising only a small piece ofiris stroma. I use a Zaldivar iridectomy forceps for thestromal excision, but any fine iridectomy forceps wouldwork as well. Any small scissors can be used for theexcision (Figure 1).

After the iris stroma has been cut, a layer of sodiumhyaluronate 1% (BioLont) is placed over the iridectomysite (Figure 2) and the area is inspected under high mi-croscopic magnification. A 25 gauge cannula attachedto a small syringe half-filled with balanced salt solution(BSSt) is then placed through the incision and maneu-vered just over the remaining pigment layer. Gentleaspiration allows complete, careful vacuuming of theentire exposed pigment layer, completing the procedure(Figure 3). The consistency of the pigment layer ismuch different from that of the stromal layer. It hasthe appearance of clumps of dust packed together.

The layer is very friable and easily broken up byaspiration.

It is important not to use the same syringe to laterhydrate the corneal incisions becauses pieces of pigment(Figure 4) will be forcibly imbedded into the cornealstroma, causing a tattoo that is only cosmetic.

Iridectomy patency is confirmed by observing thered reflex under high microscopic power.

ResultsThis procedure was been performed in 12 eyes with-

out untoward sequellae (Figure 5). All eyes had smallbasal iridectomies that were not too large or too close tothe pupil. Gonioscopy was performed preoperatively inall eyes. Postoperative gonioscopy showed minimal tono iris pigment deposition in the trabecular meshwork.Patients were thoroughly questioned and did not reportglare resulting from the iridectomy. After the learningcurve, surgeons can perform this technique with theiroverall procedure without appreciably extending the du-ration of the operation.

DiscussionThe technique of pigment vacuum iridectomy al-

lows the surgeon to be more assured that the iridectomyis totally patent and functional. It relieves the stress ofattempting to excise both layers of the iris at one time,decreasing potential trauma to the crystalline lens andzonular fibers in phakic eyes as well as to zonular fibers inaphakic eyes. It facilitates the creation of a truly basaliridectomy while decreasing the chance of making theopening so large that it may lead to glare symptoms,especially in patients with poor lid coverage of the supe-rior iris. It may decrease the deposition of dark pigmentparticles in the trabecular meshwork, which may causefuture obstruction of the drainage system and increasethe risk of glaucoma damage. In the 12 eyes in which thistechnique has been used thus far, the iridectomies have agood cosmetic appearance.

This technique may help lessen a disadvantage ofphakic refractive IOL implantation surgery; that is, thenecessity of a patent peripheral iridectomy.

TECHNIQUES: HOFFER

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