Surgical Management of the Negative Dysphotopsia Enigma

How to deal with this mysterious post-cataract surgery dilemma.

By Samuel Masket, MD, and Nicole Fram, MD

Negative dysphotopsia (ND) is a visual complaint after cataract surgery that is described by the patient as a persistent dark temporal crescent. The postoperative phenomenon was originally described by Davision, who likened this temporal darkness to “horseblinders.”¹ Although most cases resolve within the first six months after cataract surgery, some patients are very disturbed and can be quite vocal in their complaints. Fortunately, surgical methods have been devised that have proven useful in reducing the unrelenting visual symptoms of ND.

When Does it Happen?

In our experience, ND has only been reported in cases of “perfect surgery” where the IOL is well-centered within the confines of the capsule 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

At this time, it is impossible to predict who will develop ND. Though some have suggested otherwise, there is no evidence-based medicine correlating any patient characteristics, neither physiological nor psychological, to proven risk factors for ND.

Two surgical strategies have emerged as beneficial treatment of persistent visual symptoms of ND: reverse optic capture (ROC) and secondary “piggyback” IOL. 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 capsular bag. This is in keeping with the work of Vámosi et al.³

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, 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 postoperative fibrosis. The first step involves freeing the anterior capsule from the underlying optic by gentle blunt dissection and viscodissection. (Figure 1) 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. This maneuver is repeated 180 degrees away temporally, leaving the haptics undisturbed in the bag inferiorly and superiorly. (Figure 2) Should the haptics be oriented horizontally, it would be best to rotate them 90 degrees if possible. The optic is then confirmed to be elevated over the anterior capsule edge (Figure 3) and the nasal and temporal edges of the implant are anterior to the anterior capsule, whereas the haptics remain within the capsular bag. (Figure 4).

Figure 1. Gentle blunt dissection and viscodissection of the anterior capsule from the underlying optic.

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

Figure 3. Optic capture has been completed. The nasal and temporal edges of the implant are anterior to the anterior capsule (see arrows), whereas the haptics remain fully within the capsular bag.

Figure 4. Once the nasal edge has been captured (arrow), the opposite, temporal edge of the optic is elevated over the anterior capsule edge.

Secondary “Piggyback” IOL

Secondary “piggyback” IOL is the other surgical method that has proven successful for patients with symptomatic ND, as first reported by Ernest.⁴ In this method, a second IOL is implanted in the ciliary sulcus above the primary IOL/capsule bag complex. It appears that covering the primary optic/capsule junction reduces ND symptoms, although 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. However, our studies, as well as Vámosi et al., 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.

Although no parameters have been clearly established, we prefer to perform a UBM to ascertain adequate space (approximately 1 mm) between the posterior iris and the existing IOL/bag complex. We prefer the use of a threepiece silicone IOL. The AQ5010V (Staar Surgical, Monrovia, Calif.) affords a 6.3 mm optic and 14.0 mm polyimide loops, making this is an ideal design 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. For myopic errors, multiply by 1.2. For example, in the case of a 2 D hyperope, implant a + 3.0 D IOL in the ciliary sulcus.

Generally, the IOL can be implanted through a 3.0 mm incision. We prefer to use a foldable approach rather than an inserter to offer a more controlled surgical environment. A cohesive OVD should be employed to cushion the anterior segment structures as the optic opens. The leading haptic is placed under the distal iris, the optic is rotated and opened, and the trailing haptic is dialed into the ciliary sulcus. Care is taken to avoid damage to the capsule or iris. A miotic is instilled to prevent pupillary capture of the optic edge. The pupil is not dilated in the early postoperative period unless mandated by symptoms.

Conclusion

While the precise reasons why certain patients encounter ND and others do not remain a mystery, we are lucky to have beneficial forms of therapy to alleviate the problem. In our series, all patients improved with piggyback or secondary reverse optic capture, with partial or complete resolution of symptoms by three months. For some patients, surgery may not entirely resolve the phenomenon, but as we learn more about this vexing issue, additional therapies and answers will take shape. OM

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. Vámosi P, Csákány B, Németh 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;32:685–686.

	Nicole Fram, MD, is a clinical instructor of ophthalmology at the David Geffen School of Medicine, Jules Stein Eye Institute, UCLA and has an expertise in premium cataract surgery, anterior segment reconstruction, refractive surgery and cornea and external disease. Her email address is nicfram@yahoo.com.
	Samuel Masket, MD, is the founding partner of Advanced Vision Care and has been practicing ophthalmology in the Los Angeles area for over 30 years. He is a clinical professor of ophthalmology at the David Geffen School of Medicine, Jules Stein Eye Institute, UCLA and specializes in complex and complicated cataract surgery.