September 2011

 

NEWS & OPINION

 

Tools & techniques

Surgical approaches for negative dysphotopsia


by Samuel Masket, M.D., Nicole R. Fram, M.D., and Basak Bostanci Ceran, M.D.

 

rePlay

Richard Hoffman, M.D. Complaints related to post-op negative dysphotopsias can be frustrating for both the patient and surgeon. The temporal negative crescentric scotoma occurs infrequently, and in many of these patients it will improve or resolve over several months. However, when it does not improve, these patients can be some of the most demanding and unhappy individuals in a cataract practice.

In this month's column, Drs. Masket, Fram, and Ceran present an excellent review of this phenomena, explaining what works and what has not been found to be effective for eliminating these dysphotopsias. The concept that the relationship of the anterior capsulorhexis to the IOL optic rather than the relationship of the IOL optic to the posterior iris is responsible for these optical aberrations is a new revelation that may help us better treat these dissatisfied patients. Hopefully, these cases will continue to be rare occurrences in your practice. But when they do show up one day, this article will help you decide on the best surgical option for turning these patients back into happy campers.

Richard Hoffman, M.D.,

techniques editor

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Experts Dr. Masket, clinical professor of ophthalmology, Jules Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, Dr. Fram, and Dr. Ceran discuss the best ways to treat patients with negative dysphotopsia

Sinskey hook

Figure 1. A Sinskey hook is fed underneath the anterior capsule following viscodissection in an attempt to free the optic from the capsule

Sinskey hook and blunt spatula

Figure 2. The Sinskey hook and blunt spatula are used to elevate the optic edge over the capsule

cataract surgery

Figure 3. Once the nasal edge has been captured (see arrow), the opposite, temporal edge of the optic is elevated over the anterior capsule edge

Figure 4. Optic capture has been completed. The nasal and temporal edges of the implant are anterior to the anterior capsule (note arrows), whereas the haptics remain fully within the capsular bag Source: Basak Bostanci Ceran, M.D.

Clinical experience dictates that there are no beneficial medical therapies for the patient with symptomatic negative dysphotopsia (ND), originally noted by James A. Davison, M.D., adjunct associate clinical professor, University of Utah, Salt Lake City, as patients complain of a dark temporal crescent, similar to "horse blinders."1 Fortunately, surgical methods have been devised that have proven useful in reducing visual symptoms of ND. Although ND rarely induces visual disability sufficient to require an operative approach, some patients are disturbed by it and can be very vocal in their complaints. This may be particularly true when premium intraocular lenses (IOLs) have been implanted. Perhaps the most frustrating aspect of this problem for surgeon and patient alike is that ND has only been reported in cases where the IOL (any type may be causal) is well centered within the confines of the capsular bag. To our understanding, ND has never been reported with sulcus-placed PCIOLs or ACIOLs. In our investigation, we found that ND is generated from the overlap of the anterior capsulorhexis onto the anterior surface of the IOL.2 Given the latter, and in keeping with our studies, two surgical strategies have emerged as beneficial. Failed surgical strategies include bag/bag IOL exchange wherein the original implant is removed and another of different material, shape, or edge design is replaced within the capsule bag. This is in keeping with the work of Peter Vamosi, M.D., Ph.D., Budapest, Hungary, and colleagues.3

Successful surgical methods

Reverse optic capture (ROC) may be employed in a secondary surgery for symptomatic patients or as a primary prophylactic strategy. In cases of the latter strategy, the method has been applied to the second eye of patients who were significantly symptomatic following routine uncomplicated surgery in their first eye. It should be noted, however, that ND symptoms are not necessarily bilateral.

Secondary ROC, performed for symptomatic patients, may be applied if the anterior capsulotomy is not too small or too thick or rigid from post-op fibrosis. At surgery, the anterior capsule is freed from the underlying optic by gentle blunt and viscodissection. Next, the nasal anterior capsule edge is retracted with one Sinskey hook (or similar device) while the optic edge is elevated and the capsule edge allowed to slip under the optic (Figures 1 and 2). This maneuver is repeated 180 degrees away temporally (Figure 3), leaving the haptics undisturbed in the bag inferiorly and superiorly (Figure 4). (See video.) Should the haptics be oriented horizontally, it would be best to rotate them 90 degrees, if possible. Primary or prophylactic ROC is performed at the time of initial cataract surgery for the symptomatic patient's second eye. Following nuclear and cortical removal, it is beneficial to clean the anterior subcapsular lens epithelial cells meticulously, as fibrotic changes in the bag tend to occur faster and to a greater extent as a result of antero-placing the optic out of the bag. A capsule tension ring may also be beneficial, and we place them routinely in these cases (see video). Next the IOL (a three-piece model is preferred) is implanted into the bag, the optic portion prolapsed anteriorly with a spatula, and care is taken to remove the OVD from behind the optic. It should be recognized that surgical success in achieving primary or secondary ROC is highly dependent on a properly sized and centered anterior capsulorhexis. There seems to be little optical consequence of ROC, as the haptics remain in the bag; theoretically, however, a modest myopic shift would be induced, varying directly with the power of the IOL.

The other surgical method that has proven successful for patients with symptomatic ND is a "piggyback" IOL, as first reported by Paul H. Ernest, M.D., associate clinical professor, Kresge Eye Institute, Wayne State University, Detroit.4 In this method, a second IOL is implanted in the ciliary sulcus atop the IOL/capsule bag complex. It appears that covering the primary optic/capsule junction reduces ND symptoms. However, the original concept was that a piggyback lens was effective because it collapsed the posterior chamber by reducing the distance between the posterior iris and the anterior surface of the IOL. Our studies have determined that the depth of the posterior chamber is unrelated to ND symptoms.2 Symptomatic patients may be good candidates for a piggyback IOL if they are also ametropic. In order to qualify for a piggyback, the first IOL surgery should be uncomplicated with a well-centered IOL within the capsule bag. There should be no evidence of zonulopathy and the iris must be free of defects or damage from earlier surgery.

Performing the piggyback

Although no parameters have been clearly established, we prefer to perform a UBM to ascertain adequate space between the posterior iris and the existing IOL/bag complex. We prefer use of a three-piece silicone IOL. The AQ 5010V (STAAR Surgical, Monrovia, Calif.) affords a 6.3 mm optic and 14.0 mm polyimide loops; this design is ideal for the sulcus. Unfortunately, it is only available in full one diopter steps from 4.0 D to + 4.0 D; half diopter steps might be more suitable for some cases. Regarding ametropia, for hyperopic errors multiply the spectacle error by 1.5 to determine IOL power, while for myopic errors multiply by 1.2. As an example, in the case of a 2.0 D hyperope, implant a +3.0 D IOL in the ciliary sulcus.

We sense better control of the optic during implantation with the use of folding forceps rather than a "shooter." Generally the IOL can be implanted through a 3.0-mm incision. Varying with conditions, one may reopen the original incision or create one in another quadrant. A cohesive OVD should be employed to cushion the anterior segment structures as the optic opens. The leading loop is placed under the distal iris, the optic rotated and opened, and the trailing loop is dialed into the ciliary sulcus. Care is taken to avoid damage to the capsule or iris. A miotic is instilled to prevent pupil capture of the optic edge. The pupil is not dilated in the early post-op period unless mandated by symptoms (see video). EW

References

1. Davison JA. Positive and negative dysphotopsia in patients with acrylic intraocular lenses. J Cataract Refract Surg. 2000 26(9): 1346-55.

2. Masket S, Fram N. Pseudophakic negative dysphotopsia: Surgical management and new theory of etiology. J Cataract Refract Surg. In press.

3. Vmosi P, Cskny B, Nmeth J. Intraocular lens exchange in patients with negative dysphotopsia symptoms. J Cataract Refract Surg. 2010; 36(3): 418-24.

4. Ernest PH. Severe photic phenomenon. J Cataract Refract Surg. 2006; 32:685686.

Editors' note: Drs. Ceran, Fram, and Masket have no financial interests related to this article.

Contact information

Ceran: basakbostanci@aol.com
Fram: 310-229-1220
Masket: 310-229-1220, sammasket@aol.com

Surgical approaches for negative dysphotopsia Surgical approaches for negative dysphotopsia
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