With How Large a Zonular Dialysis Can Phaco Be Performed?
Surgery in the presence of a zonular dialysis can be a challenging situation for even the most experienced surgeon. The ability to perform small incision phacoemulsification with a zonular dialysis depends on the density of the lens and the stability and strength of the remaining zonules. If the patient is young and the lens is soft, the nucleus can most likely be removed with slow aspiration (Figure 6-1) even in the presence of a large dialysis if the remaining intact zonules are strong. Conversely, if the lens is brunescent in the setting of pseudoexfoliation (PXF), even a 2 clock-hour dialysis may be too large to complete successful phacoemulsification. The determination of whether to phacoemulsify the lens or to perform a large incision extraction is based on the combination of both preoperative and intraoperative findings (Table 6-1).
Figure 6-1. Traumatic cataract with zonular dialysis.
The first opportunity to diagnose zonular abnormalities is during the preoperative examination. A careful and thorough history should cover potential risk factors for zonular damage, such as trauma, previous ocular surgery, and systemic conditions such as Marfan’s syndrome and homocystinuria. A history of prior vitrectomy and chronic silicone oil tamponade can also be associated with zonular weakness.1
At the slit-lamp examination, one should look carefully for PXF. Chamber shallowing despite a normal axial length may indicate zonular laxity in such patients. One method that I use to evaluate zonular integrity at the slit lamp is to have the person look in multiple directions and then straight ahead. If significant zonular weakness exists, one might see phacodonesis during these motility exercises. If phacodonesis is present, it can be assumed that at least 25% of the zonules are weakened. If the contralateral eye is pseudophakic, pseudophacodonesis may indicate the likelihood of zonular weakness in the preoperative eye. Finally, one should maximally dilate the pupil to visualize as much of the peripheral lens as possible.
If zonular weakness is suspected, proper informed consent is crucial in managing the patient’s expectations. The patient must be made aware that both the surgery and the postoperative care may be more complicated and prolonged. The patient should also be counseled about the potential need for a vitrectomy, for dislocated lens fragments, and for the greater risk of retinal detachment and cystoid macular edema with vitreous loss. I will often paint the worst-case scenario for patients so they will expect the worst and hopefully be pleasantly surprised.
In cases of zonular dialysis, preoperative planning becomes even more important. In these patients, I will start topical NSAIDs for 1 week preoperatively because of the higher risk for intraoperative complications and postoperative cystoid macular edema. Anticipating a potentially longer operative time, I use peribulbar or retrobulbar anesthesia instead of topical anesthesia in these cases. This also makes it easier to convert to a manual ECCE if necessary.
In cases in which a large zonular dialysis is present, I will perform a scleral tunnel rather than a clear corneal incision to facilitate converting to a large-incision ECCE. The anterior capsule should be stained with either trypan blue or indocyanine green especially if capsular hooks are to be used. Of the various viscoelastics, chondroitin sulfate is best suited in cases with a zonular dialysis due to its dispersive/highly retentive properties. The chondroitin sulfate will push back the vitreous face and is not as quickly aspirated. The use of capsular hooks and CTRs will be discussed in a later chapter.
Intraoperative assessment of the degree of zonular dialysis begins when the eye is first manipulated. For example, phacodonesis might be noted during the conjunctival peritomy for preparation of the scleral tunnel incision. The degree of zonular integrity can also be evaluated during the capsulorrhexis. Puncturing the capsule with the cystotome and grasping the flap with the forceps often give the surgeon an accurate tactile sense of either normal or abnormal countertraction from the zonules. Any improper movement of the lens capsule during hydrodissection or lens sculpting should be noted. If a zonular dialysis is present, abundant chondroitin sulfate (dispersive) viscoelastic should be used to prevent anterior prolapse of the vitreous. Capsular hooks and CTRs can be placed before the start of phacoemulsification to stabilize the capsular bag and prevent vitreous prolapse (Figure 6-2).2-4 The lens must be completely hydrodissected and hydrodelineated to decrease stress on the remaining zonules when the lens is manipulated. If the lens is not fully mobile within the capsular bag, a supracapsular phacotechnique should be considered. Avoid a 4-quadrant divide-and-conquer approach, which necessitates numerous rotations within the capsule. Instead, the use of phaco chopping methods is preferred in order to minimize stress on the zonules and capsular bag.
Figure 6-2. Photo of the same lens after placement of capsular hooks.
If the dialysis is greater than 3 clock hours, the lens is brunescent, the pupil dilates poorly, and the integrity of the remaining zonules is compromised, then phacoemulsification of the lens—even with the use of capsular hooks and CTRs—may not be the best approach. In these instances, it may be safer to remove the lens through a large incision manual extracapsular approach or even with a planned pars plana lensectomy-vitrectomy. When selecting a surgical approach in the presence of a zonular dialysis, one must consider other ocular variables such as pupil size, corneal endothelial health, lens density, and the surgeon’s familiarity with using capsular hooks and CTRs.
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2. Hara T, Hara T, Yamada Y. “Equator ring” for maintenance of the completely circular contour of the capsular bag equator after cataract removal. Ophthalmic Surg. 1991;22:358-359.
3. Legler UFC, Witschel BM. The capsular ring: a new device for complicated cataract surgery. Abstract F12. Ger J Ophthalmol. 1994;3:265.
4. Cionni RJ, Osher RH. Management of profound zonular dialysis or weakness with a new endocapsular ring designed for scleral fixation. J Cataract Refract Surg. 1998;24:1299-1306.