Dec 11, 2015

Placing an IOL in the Sulcus

An intraocular lens (IOL) can be placed using remnants of a damaged capsule. The 4 most common situations (probably in order of occurrence): anterior capsular tear without extension, posterior capsular tear with intact anterior capsule, anterior capsular tear extending to a posterior capsular tear, and zonular dehiscence.

Technique   The most important part of placing an IOL in the sulcus is getting both haptics in the sulcus. The most common problem cause of decentration is to have one haptic in the sulcus and the other in the bag. One reason that it is hard to get both haptics in the sulcus is that the most common area of damage to the capsule is directly across from the wound. This area is vulnerable to radial tears as ophthalmic viscosurgical devices (OVD) are often running low as the capsulorrhexis passes this point, and this area is vulnerable as the phaco tip and chopper are active in this region. Unfortunately, this same area is where the leading haptic naturally flows during IOL insertion. If the capsule is damaged in this area, then the sulcus is poorly defined and the leading haptic can end up posterior to the anterior capsule rather than in the sulcus as intended.

When I am faced with capsule damage across from my wound, I will often inject the IOL into the eye and direct the leading haptic anterior to the iris in the anterior chamber to avoid the damaged capsule. I then will use Kelman McPherson forceps to place the trailing haptic into the sulcus. I then use an instrument like a Sinskey hook to rotate the IOL about 90 degrees so that the haptics are away from the damaged area. Then I take the Sinskey hook through a paracentesis, slide it over and hook onto the leading haptic, and pull the haptic inside the pupil and release the haptic just under the iris into the sulcus. Defining the sulcus with a viscous dispersive viscoelastic (eg, Viscoat) will greatly ease placement of the haptics.  If the anterior capsular tear is intact, round, and centered then prolapse the optic posterior into the bag.



Sulcus IOL Selection    Another very important issue for suclus IOL placement is the type of IOL. The perfect IOL for the sulcus has a large optic that is forgiving of mild decentration and permits a better view of the peripheral retina; has long haptics with an overall length that will center the IOL even in large eyes (eg 13.5 mm); and has smooth, thin haptics to reduce chaffing of the posterior leaf of the iris [1]. Thick haptics such as those of the popular single piece acylic IOLs (eg. SNWF, SA60, technic) can rub on the posterior leaf of the iris leading to iris transillumination defects, inflammtion, hemmorrhage, or pigmentary glaucoma. I prefer acrylic to silicone IOLs for sulcus implantation because patients with capsule trauma are at increased risk for retinal detachment and the possible use of silicone oil. I like the Alcon MA50 3-piece IOL (Fort Worth, Tex) because it has wide haptics, a large yet injectable 6.5-mm optic, unfolds slowly, and it is acrylic; however it has a square anterior edge and only 13.0 mm haptic length (may not be enough for longer eyes) [2]. Other prefer the Starr AQ1020V as it has a large optic, smooth anterior surface, and long 13.5 mm hatpic length; however, it does have a silicon optic and can unfold fast [1].

Please remember that some IOLs are larger than the 6.25 mm Malyugin ring used for small pupil expansion.  place the IOL optic below the malyugin ring before it uncurls completely to allow the optic to get behind the Malyugin ring  (see video).

 

As an IOL in the sulcus is more anterior than an IOL in the bag, the power of the IOL must be reduced. In Omphroy's study of 30 sulcus-based IOLs, we found that the A-constant should be lowered by about 0.8 diopters [3]. Other studies have had similar results, suggesting that we decrease the power of sulcus-based IOLs by 0.5 D to 1.0 diopters.    The shorter the AEL the bigger the adjustment that is required.  Please see Dr Warren Hills great web site on this topic: http://doctor-hill.com/iol-main/bag-sulcus.htm

It is very important to eliminate any vitreous in the area of IOL insertion. Vitreous streaming to the wound or to a paracentesis can cause IOL decentration. Careful bimanual anterior vitrectomy aided with Kenalog (Bristol-Myers Squibb, New York, NY) (not approved by the Food and Drug Administration for this indication) will greatly assist in the long-term stability of the IOL and retina.

There is no need to place a peripheral iridotomy when placing an IOL in the sulcus.

Indications for Sulcus based IOL   When the anterior capsule has a tear but the posterior capsule remains intact, one can often place an IOL in the bag. IOL insertion should be gentle, placing as little stress on the bag as possible. I prefer a single-piece acrylic in this case because the soft acrylic haptics, oriented 90 degrees away from the tear, create little tension on the bag, minimizing the risk of extension of the tear. My experience is that the single-piece acrylic is stable in the bag with a radial tear and remains centered. The disadvantage to placing this IOL in the bag with an anterior capsular tear is that should the radial tear advance to the posterior capsule during insertion, this IOL must be removed and exchanged for a 3-piece IOL suitable for the sulcus.

When the posterior capsule is torn and the anterior capsulotomy is intact, you have 2 options for the sulcus and one for the bag. One sulcus option is to simply place the IOL in the sulcus. The second, which I often use, is to place the haptics in the sulcus as described but then use a Kuglen hook to gently prolapse the optic back into capture by a well-centered anterior capsulotomy. This optic capture is very stable and seals off the vitreous from the anterior chamber.

The final option applies to stable posterior capsule tears such as round holes from a direct phaco needle strike or those tears completed with a posterior capsulorrhexis, and that is to gently place a single-piece acrylic IOL into the bag.

When the posterior and anterior capsules are both torn, it is best to seal off the area with Viscoat and to place the 3 piece IOL in the sulcus as described above.  If the IOL does not seem secure then use iris sutures to secure the haptics to the iris. 

When the zonules are weak try placing a capsular tension ring (CTR) with or without a suture. If the area of zonular loss is less than 3 clock hours, I would place a conventional CTR. If for some reason a CTR was not available, the IOL will usually remains in position in the sulcus with 3 clock hours or less of zonular dialysis especially if a 3 piece IOL is placed with the haptics in the area of the weak zonules.  If the area of zonular loss is greater than 3 clock hours, I would use an Ahmed segment sutured to the sclera or suture the eyelet of a modified CTR (Cionni). If not available, I would be very cautious placing the IOL into the sulcus with this amount of zonular loss. I would try to place the IOL in the sulcus but have a very low threshold for iris suture fixation. Another option is to use Agarwal's technique to glue the haptic into a scleral tunnel [4].

Summary  Capsule damage and zonular weakness are common in our surgical practice.  We must have sulcus IOLs ready and be prepared for their insertion.   It is important to be ready for this rare but

References

1. Chang DF et al . Complications of sulcus placement of single-piece acrylic intraocular lenses: recommendations for backup IOL implantation following posterior capsule rupture. J Cataract Refract Surg. 2009 Aug;35(8):1445-58.
2. Chang DF, Curbside Consultation in Cataract Surgery: 49 Clinical Questions, Chapter 33: When and How Should I Implant an Intraocular Lens in the Ciliary Sulcus?, Slack, NJ, 2007
3.  Maassen, J, Oetting T, Omphroy L. A constant for sulcus based MA60BM. Unpublished data presented at: University of Iowa Ophthalmology Resident Research Conference; Iowa City Iowa, May 19 2006. link
4. Kumar DA, Agarwal A, Prakash G, Jacob S, Saravanan Y, Agarwal A. Glued posterior chamber IOL in eyes with deficient capsular support: a retrospective analysis of 1-year post-operative outcomes. Eye (Lond). 2010 Jul;24(7):1143-8.

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