Exfoliation syndrome (XFS) is an age-related disorder characterized by production of an extracellular matrix present in the anterior segment of the eye but also present in other tissues. An association with LOXL1 variants is present in most patients with XFS. However, there seems to be other genetic or possible environmental factors that may be involved as well such as solar exposure and or geographic history.1–4
In the anterior segment exfoliation material is deposited on the lens epithelium, the corneal endothelium, pupillary edge, on the ciliary processes, and on the zonules. There is frequent peripupillary pigment loss, along with iris sphincter and mid peripheral iris transillumination defects. Pigment can be deposited on the corneal endothelium and in the angle.
The presence of XFS is associated with an overall increase in cataract surgical complications.5–7 There are a number of technique modifications as well as new devices and adjunctive measures that can reduce the incidence of intraoperative complications. Although cataract surgery may go uneventfully in XFS patients there remains the problem of late-onset intraocular lens (IOL) subluxation. Late-onset IOL subluxation generally occurs about 8.5 years after cataract surgery, whether the procedure was complicated or routine.7
Cataract surgery in patients with XFS like all cataracts demands a well-thought-out game plan. Initial examination should include a careful assessment for zonular stability, specifically assessing whether there is asymmetry in the anterior chamber depth. Preoperatively, it is important to note the pupil size after dilation to plan for enlargement if necessary.
PUPIL MANAGEMENT IN XFS
A small pupil after dilation is a sign for potential intraoperative complications.
The use of intracameral lidocaine and epinephrine along with viscoelastic may produce a sufficient pupil size. If the pupil still needs dilation then one can use a number of devices to enlarge the pupil. The most commonly used include Greieshaber hooks,8 and the Malyugin Ring.9
Although one can certainly proceed with phacoemulsification of the lens through a small pupil the resultant small capsulorhexis can produce rotation stress on the zonules. Furthermore, the small pupil can make it difficult to completely clean the cortex that can lead to retained cortex, increasing the chance for inflammation and capsule phimosis with attendant late spontaneous IOL/bag dislocation.
The capsulorhexis should be 5.5 mm—enough to cover the entire peripheral part of the IOL. If it is too small this can lead to capsulophimosis, which may lead to spontaneous late subluxation.10
Hydrodissection frees up the lens for rotation. It is important because rotation issues can lead to difficult rotation and further damage to the zonules.
NUCLEUS MOBILIZATION, DISASSEMBLY, AND CORTICAL CLEANUP
All maneuvers should be performed without shallowing of the anterior chamber as this puts undue stress on the zonular apparatus. When nuclear rotation is needed, it should be performed with a bimanual technique (Fig. 1).11 Clearly nuclear disassembly can induce zonular stress particularly when rotational forces are applied to the nucleus and this can lead to zonular dialysis under any circumstance and particularly in XFS (Fig. 2).11
There are a number of disassembly techniques available, each of which has maneuvers for nuclear removal and it is good to know them all. One (which remains the most commonly taught and used) is the divide and conquer maneuver. In this technique the phaco machine starts with sculpt mode which uses high power without occlusion to makes ≥4 grooves that are deep centrally. These grooves are then divided (cracked) and the phaco machine is then set to quadrant removal mode to bring the pieces to the center of the pupil and just above it and with higher flow and phaco constant position 3—no occlusion—the pieces follow and are safely removed. To decrease the flow and also the number of nuclear rotations one can use “chop techniques.” I almost always use a prechop device (modified Akahoshi style) that allows me to chop the nucleus into ≥4 pieces with no energy from the phaco trip. Once they are cracked one can debulk the pieces but usually I will bring 1 piece up central and just above the capsule bag and with moderate flow each piece is easily removed. If the nucleus is hard then one may need to use either a vertical or horizontal chop technique. In these variations the phaco tip is embedded deep in the nucleus and a sharp second instrument is used to split the nucleus and removed similar to the previous techniques. A variety capsular support devices can aid nuclear removal.
There remain 3 other techniques that surgeons should be familiar with. First involves sectioning the lens into more manageable pieces with an instrument called the ultrachopper (Fig. 3). Second, the femtosecond laser can also be very helpful in XFS cases as it produces a reliable capsulorhexis and it can soften the nucleus for removal (Fig. 4). Finally everyone should be familiar with small incision extracapsule removal. There are dark (even black) lenses with loose zonules that require an extracapsular cataract removal, as these lenses are too hard for even the retina phacofragmatome to disassemble.
Once the nucleus has been removed then the cortex must also be elegantly removed. This is performed best by using tangential stripping rather than conventional radial technique. As illustrated in Figure 5, tangential stripping puts less stress on the zonules than a radial approach.
We now know that eyes with XFS can experience spontaneous IOL subluxation or dislocation 8.5 or so years after routine surgery.6,7 Originally, we thought that a capsular tension ring might reduce this and certainly they do help to center the lens and help equalizing the forces.12,13 However, we now have numerous examples of dislocated lenses with capsular tension rings in them but 1 common feature is severe capsule phimosis, so we now suggest removing as much anterior capsule lens cells—usually with a Singer sweep—this has been shown in studies in Oliver Findl’s laboratory (Fig. 6).14 Capsule phimosis, otherwise known as capsular contraction syndrome places undue tension on the zonule leading to late-onset IOL dislocation.
One controversy that will take time to resolve involves using 3-piece lenses with placement of the haptics not in the bag but in the sulcus. Others also purposefully open the posterior capsule and push the optic to capture it. If the haptics become ensconced in the sulcus this may prevent subluxation but it is important to realize that exfoliation material is deposited onto these structures that may weaken or inflame.
Multifocal lenses can lead to significant visual issues. Moreover, lenses that are pupil dependent may not work in XFS eyes because of small pupils. Toric lenses can be used if there is no evidence of zonular weakness but should be elegantly rotated into position and the patient warned about possible rotation issues.
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Keywords:Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved.
exfoliation syndrome; pupil dilation; zonular integrity; capsular support devices; nuclear dissembly