* Editor's Note: The last three articles in this cover series focus on the considerations of refractive lens exchange (RLE), including basic and additional considerations. First, John So-Min Chang, MD, presents his surgical technique for RLE in this article. Irmingard M. Neuhann, MD, FEBO, and Thomas F. Neuhann, MD, then discuss extra surgical considerations. Lastly, Samuel Masket, MD, reviews ethical considerations associated with RLE.
When performing clear lens extraction (ie, refractive lens exchange; RLE), the surgeon is placed under significant pressure. Because the RLE patient already sees well with contact lens or glasses preoperatively, any loss of vision after RLE is unacceptable and poorly tolerated by the patient. Intraocular surgery carries significantly more risk than LASIK or other extraocular surgery; however, for presbyopia and high myopia or hyperopia, IOLs offer better stability, a higher success rate, and better quality of vision than LASIK.
SURGICAL TECHNIQUE
My surgical technique starts with reiteration of the risks involved with intraocular surgery. This occurs while the patient is on the table, before we start surgery. One point I stress is that not all eyes are normal and not all surgeries are successful. Should I encounter any difficulty, I will not use the multifocal or accommodating IOL but instead replace the crystalline lens with a monofocal IOL. I will often target -2.0 for that eye if the other eye is emmetropic. The concept of monovision would have already been shown and explained to the patient; this back-up plan is discussed in my preoperative consultation. If the patient cannot accept monovison, then emmetropia would be my target.
Prep. The patient is prepared with 10% povidone-iodine lid scrub, and left to dry for 4 minutes. Two drops of 5% povidone iodine are instilled into the eye simultaneously, as prophylaxis against postoperative endophthalmitis.1
Incision. I use a 2.2-mm temporal clear corneal incision for the Restor (Alcon Laboratories, Inc., Fort Worth, Texas) or 2.7-mm temporal clear corneal incision if I use the Array (no longer manufactured), ReZoom, or Tecnis multifocal IOLs (all from Advanced Medical Optics, Inc., Santa Ana, California).
Because there is minimal manipulation, I make the tunnel longer than my usual cataract surgery. A longer tunnel should decrease the risk of endophthalmitis. Often, the patient is aged in his 40s, and the crystalline lens is still soft. Once the capsule is opened, it will imbibe water and swell, at which time the anterior capsule may extend outward. Therefore, I treat it like a pediatric cataract, filling the anterior chamber with a lot of ophthalmic viscosurgical device (OVD). I ensure that there is plenty of OVD pressure on the anterior capsule to keep it from extending outward.
Capsulorrhexis. The capsule is peeled carefully, and I frequently regrab the capsule at the flap base. A circular, well-centered, 5-mm capsulorrhexis is ideal. Should the posterior capsule break, I consider placing the multifocal lens haptic in the sulcus and pushing the optic behind the anterior capsular opening. This decision depends on the lens used and whether the capsulorrhexis is centered or not. I have done this for both diffractive and refractive lenses; it has worked reasonably well if the capsulorrhexis is central. Aralikatti et al2 reported that although it was not ideal, the Array multifocal IOL could also be placed in the sulcus (anterior to the capsule).
Hydrodissection. The most important part of my technique is the use of a Chang Hydrodissection Cannula (K7-5466; Katena Products, Inc., Denville, New Jersey; Figure 1) to hydrodissect the nucleus (Figure 2). I then turn the cannula upside down, with the irrigating port facing up, and divide the nucleus in half by manually pushing the cannula vertically toward the posterior capsule. I use multiple downward stabbing movements (ie, cake cutting; Figure 3) to split the nucleus in half. I do not drag the cannula, as this may tear the capsule. Because the lens is clear, one can often see the cannula touch the posterior capsule, but because the back of the cannula is curved and smooth, the posterior capsule is unlikely to tear. One does not need to touch the capsule; however, with more experience, even touching the posterior capsule is safe—as long as one does not push too hard. One must remember that the lens is shallower in the periphery. The proximal quarter of the lens does not need to be punched or separated.
Phaco. Once hydrodissection is complete, the rest is simple. With the phaco instrument on phaco chop mode, with high vacuum (400 mm Hg) and flow rate 28 cc/min, I suck up the distal left half (Figure 4). The lens lifts easily as I sweep along the left side to suck up that half of the lens. The right half of the lens will keep the posterior capsule in place. The phaco tip is then directed toward the distal right half. The right half of the lens is sucked up and removed accordingly (Figure 5). No phaco energy is needed.
Sometimes the second half does not lift well or the lens cracks, leaving the proximal right quarter unmoved. In this case, I release the foot pedal (position 0) to slightly collapse the anterior chamber. I then nudge the proximal anterior capsule with my phaco tip to push the nucleus into the center, and remove it with phaco suction. If one is uncomfortable with this maneuver, the I/A instrument may be used to remove this quarter. The remainder of my technique is the same as my routine cataract surgery.
I find this method the most friendly to the capsule, zonules, and endothelium. I have not broken a capsule yet (Figure 6).
John So-Min Chang, MD, is the Director of Guy Hugh Chan Refractive Surgery Centre at Hong Kong Sanatorium and Hospital, Happy Valley, Hong Kong. Dr. Chang states that he has received lecture honorarium from Alcon Laboratories, Inc., and Advanced Medical Optics, Inc. He may be reached at tel: +852 2835 8885; fax: +852 2835 8887.
- Wu PC, Li M, Chang SJ, Teng MC, Yow SG, Shin SJ, Kuo HK. Risk of Endophthalmitis After Cataract Surgery Using Different Protocols for Povidone-Iodine Preoperative Disinfection. J Ocul Pharmacol Ther. 2006;22:54-61.
- Aralikatti AK, Tu KL, Kamath GG, Phillips RP, Prasad S. Outcomes of sulcus implantation of Array multifocal intraocular lenses in second-eye cataract surgery complicated by vitreous loss. J Cataract Refract Surg. 2004;30:155-160.
