19 Optic Capture
19.1 Introduction
The desired outcome of intraocular lens (IOL) implantation is a well-centered and stable lens that enhances vision while avoiding corneal and uveal touch. In the early development of intra ocular lenses Dr. Cornelius Binkhorst found that capsule fixation of the IOL was the most ideal placement for long term safety. 1 , 2 His 2 loop irido-capsular lens that stabilized the IOL with the pupil until at least one loop of the lens was fixed by fibrosis in the capsular bag was the precursor to the in-bag posterior chamber (PC) IOLs now in use. A stable centered outcome is now, in most instances, achieved by at least both loops, if not also the optic edges in the bag. However, there are instances when in-bag fixation may not be a possibility due to tears or defects in the capsule. Several methods have been described in the literature to achieve IOL fixation in these instances. Both sulcus placement of posterior chamber IOLs (PCIOL) and implantation of anterior chamber IOLs (ACIOL), although technically simple, have been known to be associated with several early and late complications. 3 , 4 The other options are the use of scleral or iris-fixated lenses. 4
In this chapter, we describe a number of Optic Capture methods to take advantage of the intact portion of the capsule to achieve safe and stable implantation of IOLs in the presence of capsule defects where there is still adequate zonular support of the capsule. By using these methods one can achieve a centered, stable lens along with a barrier to vitreous migration.
We will first describe optic capture techniques for various situations occurring in primary lens surgery. In these techniques, one uses the anterior continuous curvilinear capsulorhexis (ACCC) or posterior continuous curvilinear capsulorhexis (PCCC) to capture the PCIOL. Later we will also describe methods for secondary surgery by which capsular membranes may be utilized to fixate IOLs. All of these techniques result in capsule fixated, stable, and centered, IOLs which produce refractive results similar to in-bag placement while avoiding complications resulting from iris and corneal touch.
19.2 IOL Capture Using ACCC/PCCC
There are at least six ways to utilize an ACCC, PCCC, or both, for capsular fixation of a PCIOL, These have been described by us earlier. 5 The choice of technique will depend upon the clinical situation and the type of capsular breach that precludes in-bag placement. We will now describe each technique in detail.
19.2.1 Anterior CCC IOL Optic Capture- “Neuhann Rhexis Fixation”
This technique was first described in video format by Tobias Neuhann in 1991 for safe IOL fixation in the presence of a large posterior capsular tear. 6 The method takes advantage of the tear-resistant stability of a CCC. An anterior CCC results in a tear-resistant opening that facilitates phacoemulsification cataract extraction and IOL implantation in the capsular bag. 7 In the event of a large or peripheral posterior capsule tear and loss of capsular bag support of an IOL, an intact anterior capsulorhexis opening can be utilized to provide support and stability for a sulcus-placed IOL by using optic capture. This ensures fixation and centration of the IOL by the ACCC capture, minimizing the risk of haptic and/or optic chafing of uveal tissues.
To capture the IOL optic, the capsulorhexis opening must be an intact curvilinear opening and must be at least 1.0 to 2.0 mm smaller than the optic diameter. To achieve good centration of the optic the ACCC must also be reasonably well centered. This method of fixation is ideal in the situation of a large posterior capsule tear that does not extend around the equator of the capsule to the anterior CCC and is too large for conversion to a PCCC for safe placement of an IOL in the capsular bag. If vitreous prolapse has occurred, an anterior vitrectomy is performed. Care should be taken to avoid extending the posterior capsule tear or violating the anterior capsule edge with the vitrectomy hand piece. Separating the infusion and vitrectomy hand piece helps to avoid hydration of the vitreous and creation of positive pressure, which might extend the posterior capsule tear.
Once all prolapsed vitreous has been removed, an ophthalmic viscosurgical device (OVD) is placed in the anterior chamber and ciliary sulcus. The IOL can then be placed in the ciliary sulcus. If the anterior capsulorhexis opening is considered reasonably centered and smaller than the IOL optic, placing the edges of the optic through the capsulorhexis is performed with gentle pressure on one side and then the other side of the anterior surface of the IOL, 90 degrees from the haptic–optic junctions. The haptics remain in the ciliary sulcus while the IOL optic is captured posteriorly through the capsulorhexis opening (Fig. 19.1). Viscoelastic in the anterior segment is aspirated as usual. The viscoelastic behind the IOL does not have access to the trabecular meshwork and does not cause an elevation in intra-ocular pressure (Videos 19.1 and 19.2).
19.2.2 Sulcus-Placed Haptics and Optic Capture through the PCCC
This technique is useful in the event of one or more large tears in the anterior CCC extending to the equator when secure placement of the haptics in the capsular bag is compromised. It may also be used in cases where the anterior CCC is larger than the optic thus preventing capture through the anterior CCC. A purposeful PCCC is formed under a highly cohesive viscoelastic to maintain positive pressure for control and to prevent extension of an anterior capsule leaflet tear to the PCCC. The PCCC is started with a pulling tear opening of the PC using a 27 G hypodermic needle with a 90 degree micro bend at the tip formed by pushing the tip against a smooth handle of a forceps so that it can function as a hook. A sharp cystotome may also be used to open the capsule without disturbing the vitreous if it is used as a hook. Then more viscoelastic is placed through the opening to protect the vitreous during the PCCC. Additional viscoelastic is added as the PCCC is progresses. An inadvertent small posterior capsule tear may be converted to a PCCC and used for this purpose. 8 For PCCC optic capture the IOL is positioned in the ciliary sulcus and the optic captured posteriorly through the anterior and posterior capsule openings (Fig. 19.2). In this manner, IOL centration is maintained and the possibility of Elschnig’s pearl formation posterior to the IOL prevented.
The capture process is achieved by gentle pressure on one half of the IOL optic 90 degrees from the haptic–optic junction followed by slow and gentle pressure on the other half of the optic until both sides of the optic are behind the capsulorhexis opening. Vitrectomy is performed if vitreous herniates through the posterior capsulorhexis opening.
Debroff and Nihalani 9 have described using this technique in pediatric eyes to capture a sulcus placed lens through both the ACCC and PCCC to promote nearly 360 degree capsular fusion to prevent visual axis opacification (Videos 19.3–19.5).
19.2.3 Haptics in the Capsular Bag and Optic Capture through the PCCC
This technique was originally described in 1994 by Gimbel and DeBroff 8 to maintain a clear visual axis after pediatric cataract surgery. It has been shown to prevent PCO and maintain excellent IOL centration and is particularly applicable in children younger than 6 years.s. Literatur , s. Literatur , 12 It may also by used when Nd:YAG capsulotomies may be difficult or impossible due to physical or geographic constraints should posterior capsule opacification occur after cataract surgery in adults. A PCCC is performed after cataract removal and before or after IOL placement in the capsular bag. An advantage of performing the PCCC after IOL placement is the ability to discontinue the PCCC in the event of peripheral extension of the PCCC. Alternatively, the posterior capsulorhexis can be performed before IOL implantation (Fig. 19.3 and Videos 19.6 and 19.7).
Technique of PCCCs. Literatur , s. Literatur
A planned primary posterior capsule opening can be created to prevent secondary cataract formation or to remove a posterior plaque. Under OVD a small central triangular tear is made in the posterior capsule by hooking, lifting, and tearing to avoid disturbing the vitreous with a barbed, disposable, 27 gauge needle or cystotome. Healon GV is injected through this small opening to fill Berger’s space and push the vitreous back and protect it while the PCCC is performed. The tear is usually first directed radially to the 3 0’clock position and then turned and continued counter clockwise for 360 degrees. The best control of the progressing tear in the posterior capsule is achieved with a pointed capsulorhexis forceps. The capsule flap is grasped near one point of tearing and the tear turned in the desired direction. The circular tear is accomplished by using CCC principles and strategies. Additional viscoelastic material can be placed through the advancing tear of the posterior capsule to push the vitreous face away as the tear enlarges the opening. The viscoelastic agent should not push the flap posteriorly, as this makes it difficult to grasp the posterior capsule tag. Additionally, if too much viscoelastic material is pushed through the opening, it may extend the tear in an unpredictable fashion. The end result should be a well-centered PCCC concentric to and equal or smaller than the CCC (Fig. 19.4). Ideally, the PCCC diameter should be 1.0 to 1.5 mm smaller than the IOL optic. The PCCC is kept small enough to capture the optic but large enough to allow the IOL optic to pass through so that maximum integrity of the posterior capsule is preserved and posterior capture of the IOL optic is facilitated. The posterior capsule is more elastic and will stretch more than the anterior capsule so the PCCC may be smaller than the ACCC.
Before the posterior capsule circular tissue is removed, scissors may be used if necessary to cut any adherent vitreous strands. An anterior vitrectomy is necessary only if vitreous presents through the posterior capsular opening.
All of our cases, including the early cases were done without anterior vitrectomy and none has had opacification of the visual axis (see accompanying blue box). Other authors found reticular fibrosis of the anterior vitreous face causing opacification when using this technique without vitrectomy. 13 They had, however, been using one piece PMMA IOLs with oblique haptic-optic junctionss. Literatur , 14 whereas we had used PMMA IOLs with 90 degree haptic-optic junctions similar to haptic-optic junctions of 3 piece IOLs. Since using 3 piece foldable IOLs we have still not had any opacification of the visual axis, even though we did not use vitrectomy after the PCCC at the time of surgery. Other investigators are using this technique and have also had similar results.s. Literatur
Posterior capture of the IOL optic is performed under a highly viscous cohesive OVD, and the capture process is achieved by gentle pressure on one edge of the IOL optic, 90 degrees from the haptic–optic junction followed by slow and gentle pressure on the other edge of the optic to push the optic edges through the capsulorhexis opening. An anterior vitrectomy may be performed for any vitreous herniating through the posterior capsulorhexis opening. If the pressure on the optic edge is gentle, and the movement of the IOL is slow to allow the viscoelastic to shift, the risk of vitreous herniation is very small. As mentioned above, Debroff has described placing the haptics in the sulcus rather than in the intact capsular bag for PCCC optic capture in pediatric eyes. 9 This technique is less challenging because the capsular bag may be difficult to find with both capsules open, especially if the openings are similar in size.
Menapace 15 describes PCCC and optic capture in adult eyes using the term “button-holing” of the optic. This procedure was found to be safe and effective in preventing retro-lenticular opacfication as well as capsular fibrosis by preventing contact between the anterior capsule and the lens optic. He recommends performing a 4–5-mm PCCC under low-viscosity cohesive OVD followed by circumferential visco-separation of the anterior hyaloid from the posterior capsule. This technique makes after-cataract prevention independent of IOL material or optic edge design.
As described by us earlier this technique may also be used for a small PC tear occurring near the end of phacoemulsification or during Irrigation-Aspiration. A small tear can be blunted or converted to a PCCC followed by optic capture. 16
The material of the IOL for optic capture is not important but the thinner the optic the easier it is to achieve capture. The haptic size and thickness, however, is important. The thick haptics of current acrylic IOLs makes them inappropriate for sulcus placement. Three piece IOLs with PMMA haptics are preferred. The overall length of the IOL is immaterial because the lens is stabilized with the optic capture and not the sulcus or bag placement of the haptics.
PCCC with Optic Capture in Pediatric Eyes – Long-Term Follow Up
We reviewed the records of all consecutive pediatric patients undergoing cataract surgery with PCCC and IOL optic capture without anterior vitrectomy from April 1993 to August 2005 for postoperative outcomes. Twenty-three eyes were included in the analysis. A clear central visual axis was achieved in all eyes, and maintained at a mean follow-up of 10.3 ± 1.04 years. The mean patient age at the time of cataract surgery was 6.2 years ± 2.9 yrs (range: 2.7 to 12.6 years). The mean preoperative and postoperative BCVA at the last follow-up visit were 0.55 ± 0.09 logMAR (20/71) and 0.35 ± 0.09 (20/45), respectively. The mean preoperative and postoperative spherical equivalents at the last follow-up visit were +1.40 ± 0.4 and -1.27 ± 0.3 diopters, respectively. There were no postoperative complications associated with this technique, and no eye developed glaucoma.
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