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Primary reverse optic capture an option for negative dysphotopsia

The use of a three-piece IOL is recommended, and a capsular tension ring helps distend the capsular bag.

Issue: June 10, 2015

ByAmar Agarwal, MS, FRCS, FRCOphth

ByPriya Narang, MS

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Davison first reported “negative dysphotopsia” and described it as an undesired optical phenomenon following an uncomplicated cataract surgery, characterized by dark black crescent-shaped shadows in the temporal field of vision. The incidence of negative dysphotopsia varies in different studies. Davison reported an incidence of 0.2%, whereas Osher reported an incidence of 15.2% on the first postoperative day, which decreased to 2.4% after 2 years.

Placement of a well-centered IOL within the capsular bag is the ultimate aim of a successful cataract surgery. Sequential postoperative complaints of negative dysphotopsia can be disheartening to both the surgeon and the patient. Symptoms of negative dysphotopsia have been observed to either disappear or decrease in intensity in some of the cases, but they often persist in a few cases, leaving patients extremely disappointed and emphatic about the shadow perceived.

Theories

Various theories have been formulated for the cause of negative dysphotopsia, but the exact etiology remains elusive. Secondary reverse optic capture has been accepted to work well in patients with negative dysphotopsia, although the mechanism by which it works is still controversial. Masket and colleagues described that a shadow is generated due to the overlap of the anterior capsulorrhexis onto the anterior surface of the IOL and is due to the reflection of the anterior capsulotomy edge projected onto the nasal peripheral retina. Performing reverse optic capture eliminates this reflection, and hence the symptom of negative dysphotopsia abates. Holladay and colleagues suggested that after reverse optic capture, the anterior capsule comes in direct contact with the posterior capsule and eventually both surfaces become translucent due to opacification, thereby eliminating or filling the shadow due to scattering effect.

Some studies formulate that negative dysphotopsia appears to be more related to the patient’s anatomical structure, which is expected to be the same in the other eye. However, it is necessary to state that negative dysphotopsia symptoms may not necessarily be bilateral.

Treatment

Secondary reverse optic capture is one of the surgical procedures adopted for alleviating the symptoms of negative dysphotopsia. After cataract surgery, when a patient complains of negative dysphotopsia, secondary reverse optic capture can be done, which involves a careful separation of the edge of the anterior capsule from the anterior surface of the IOL. It can be also done as a primary procedure in cases that have a history of negative dysphotopsia after surgery in the previous eye. In literature, Masket and colleagues first reported the use of a capsular tension ring with the procedure of primary reverse optic capture.

Figure 1. A well-centered 5-mm capsulorrhexis is performed.

Figure 2. A capsular tension ring is inserted in the capsular bag after nuclear emulsification.

Figure 3. A blunt spatula is inserted beneath the IOL to levitate the optic out of the confines of the capsular bag. A Lester hook assists to retract the capsulorrhexis margin and helps in the entrapment of the IOL.

Figure 4. Image on the first postoperative day.

Images:Agarwal A

Achieving a well-centered capsulorrhexis around 5 mm in diameter (Figure 1) is essential and a prerequisite for primary reverse optic capture. After nuclear and cortical removal, it is beneficial to clean the anterior subcapsular lens epithelial cells meticulously because fibrotic changes in the bag tend to occur faster and to a greater extent as a result of placing the optic out of the bag. The use of a capsular tension ring is effective because it helps to distend the capsular bag (Figure 2) in a freshly operated eye, especially when the optic is prolapsed out of the confines of the capsular bag. It is recommended to use a three-piece IOL because it is comparatively easier to prolapse it anteriorly and ensure the entrapment of the capsulorrhexis margin behind the optic of the IOL (Figures 3 and 4). With a one-piece IOL, it is difficult to place the entire 360° of optic above the anterior capsular rim, yet the 180° opposite edges can be easily placed with haptics remaining confined to the capsular bag. Clinically, difficulty in entrapment of a one-piece IOL is observed in primary reverse optic capture because the edges of the capsulorrhexis margin in a freshly operated eye tend to be slippery as compared with the fibrotic capsule margin in cases of secondary reverse optic capture that were operated over a period of time. Recent reports in the literature suggest that an anti-dysphotopic IOL designed by Masket has a peripheral groove to facilitate the entrapment of the anterior capsule in the groove. Until detailed reports are published, surgeons should continue to use a three-piece IOL.

Although it is a contentious issue of whether to perform primary reverse optic capture, it is observed that patients who undergo secondary reverse optic capture never experience negative dysphotopsia in the other eye when primary reverse optic capture is performed prophylactically.