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From the editor

Negative dysphotopsia following cataract surgery

Mamalis, Nick MD

Journal of Cataract & Refractive Surgery: March 2010 - Volume 36 - Issue 3 - p 371-372
doi: 10.1016/j.jcrs.2010.01.001
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There are two kinds of light—the glow that illuminates and the glare that obscures.

James Thurber

One of the most vexing symptoms that can affect patients following modern cataract surgery is dysphotopsia. This photic phenomenon, which occurs in pseudophakic patients, has many different forms. So-called positive dysphotopsia is usually noted as phenomena such as light rings, arcs, streaks, flashes, and halos that may interfere with vision. These images are noted near the central axis of vision and can be induced by peripheral light sources. Positive dysphotopsia is usually related to bright artifacts of light on the retina. Tester et al.1 used the term dysphotopsia to describe the visual phenomena encountered by phakic and pseudophakic patients, including flashes of light, glare, and light sensitivity.

Negative dysphotopsia involves the blockage of light from certain portions of the retina and is manifested by a dark crescent or curved shadow that can appear similar to a scotoma in the peripheral temporal field of vision. The exact etiology of negative dysphotopsia remains an enigma. Osher2 postulates that negative dysphotopsia symptoms occurring relatively soon after cataract surgery and disappearing after the first few weeks may be associated with edema of the clear corneal incisions. Davison3 describes the phenomenon of a temporal dark shadow in the patient's vision, which is called a negative dysphotopsia. Although these symptoms were initially reported in eyes with a high-refractive-index hydrophobic acrylic intraocular lens (IOL) with sharp optic edges, they have now been reported with many IOL materials and designs, including 3-piece silicone IOLs and hydrophilic acrylic IOLs.

The question of why this dark shadow of light occurs temporally is likely because the nasal retina may extend farther anteriorly than the temporal retina as well as because light coming in nasally may be somewhat tempered by the nose, eyebrow, and cheek. However, light coming from the temporal side of the eye that projects to the nasal-most retina may be deflected by the edge of the IOL or even reflected internally by the relatively square edge of an IOL away from the nasal retina. This results in a crescent-shaped shadow noted in the temporal field of vision.

The incidence of serious negative dysphotopsia varies, but in most studies it is relatively small. Davison3 reports an incidence of 0.2% in a large series of patients with truncated acrylic optic IOLs. Osher2 reports an incidence of 15.2% on the first postoperative day, which decreased to 2.4% after 2 years. However, he found that the symptoms were not disturbing enough to necessitate IOL exchange.

Several remedies have been suggested for negative dysphotopsia symptoms that become severe and do not decrease over time.4,5 Intraocular lens exchange with a round-edged IOL inserted into the capsular bag or the ciliary sulcus has been advocated by many surgeons who have dealt with this problem. Other options include prolapsing the optic into the ciliary sulcus or implanting a piggyback IOL in the ciliary sulcus. This would theoretically decrease the distance between the iris plane and the IOL, which might decrease the negative dysphotopsia symptoms.

In this issue, Vámosi et al. (pages 418–424) present the results of a study of IOL exchange in patients with severe negative dysphotopsia. The incidence of this in the pseudophakic patient population was 0.13%—5 eyes in 4 patients out of 3806 routine cataract procedures. The symptoms were related to a hydrophobic acrylic IOL in 2 of the eyes, but in the other 3 eyes, they were associated with a hydrophilic acrylic IOL. In all the patients, the IOLs were noted to be well-centered and the optic fully covered by the anterior lens capsule. Using ultrasound biomicroscopy, Vámosi et al. evaluated the difference in the iris-to-optic distance in the patients who were symptomatic and in a nonsymptomatic control group. The difference was not statistically significant; however, in the patient in whom the secondary IOL was initially left in the capsular bag, the symptoms persisted, whereas in patients in whom the secondary IOL was placed in the ciliary sulcus, the symptoms resolved. The reduction of the iris–IOL distance following IOL exchange seemed to be related to resolution of the severe negative dysphotopsia symptoms.

Negative dysphotopsia may be a more common problem than initially realized. If patients are questioned about symptoms, postoperative negative dysphotopsia may be mentioned relatively frequently. However, the symptoms mentioned in questionnaires tend to be very mild or moderate and generally decrease over time; they are often not disturbing to patients. Significant negative dysphotopsia symptoms have now been reported with virtually all IOL materials, and while the incidence appears to be more significant with square-edged, high-refractive-index IOLs, the symptoms have been reported with IOLs with various optic-edge designs. Other factors that may be related include axial length, anterior chamber depth, and distance from the iris to the IOL optic. Finally, some patients may be particularly vulnerable or particularly sensitive to dysphotopsia and may require additional surgical treatment. Despite many years of study and discussion, the issue of negative dysphotopsia remains an enigma.

REFERENCES

1. Tester R, Pace NL, Samore M, Olson RJ. Dysphotopsia in phakic and pseudophakic patients: incidence in relation to intraocular lens type. J Cataract Refract Surg. 2000;26:810-816.
2. Osher RH. Negative dysphotopsia: long-term study and possible explanation for transient symptoms. J Cataract Refract Surg. 2008;34:1699-1707.
3. Davison JA. Positive and negative dysphotopsia in patients with acrylic intraocular lenses. J Cataract Refract Surg. 2004;26:1346-1355.
4. Masket S, editor. Consultation section: cataract surgical problem. J Cataract Refract Surg. 31. 2005. 651-660. addendum 1487–1489.
5. Masket S, editor. Consultation section: cataract surgical problem. J Cataract Refract Surg. 32. 2006. 908-913.
© 2010 by Lippincott Williams & Wilkins, Inc.