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Consultation section

Cataract surgical problem: Reply 10

Vasavada, Abhay R. FRCSa

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Journal of Cataract & Refractive Surgery: April 2002 - Volume 28 - Issue 4 - p 586-588
doi: 10.1016/S0886-3350(02)01291-9
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The aim in these cases is to stabilize the capsular bag by reducing anterior capsule fibrosis and contracture. These are major risk factors as they may cause progressive weakening of the zonules.

The preoperative examination should begin with the following in an undilated eye: specular microscopy for endothelial cell density, IOP measurement, and slitlamp evaluation to detect iris stromal atrophy and iridodonesis. After the pupil is maximally dilated, the following should be assessed: pupil size, the presence of phakodonesis to detect zonular weakness, the extent and grade of pseudoexfoliation, zonulysis or subluxation, the cup-to-disc ratio, and the disc.

Counseling is mandatory to warn the patient of potential intraoperative complications and postoperative outcomes. The patient's written consent should be obtained before surgery.

For surgery, topical anesthesia is preferred. Peribulbar anesthesia involves pressure and massage to the globe that can cause BAB breakdown and may traumatize the already weak zonules.

Surgery is performed using a closed-chamber technique. After a 3-plane temporal limbal incision is created, a dispersive viscoelastic material such as sodium hyaluronate 3%-chondroitin sulfate 4% (Viscoat®) should be used to help protect the compromized endothelium, particularly if the cell density is low. If the pupil does not dilate, I refrain from using dilating instruments or retractors to minimize intervention and trauma. Initially, the capsulorhexis should be small, within the pupil edge. After the anterior capsule is pierced and a slit made, the capsulorhexis is created with a forceps as there is no counter resistance. Furthermore, using the forceps prevents pulling the capsule and reduces stress on weak zonules.

Multiple-quadrant hydrodissection is advisable as it ensures good corticocapsular cleavage and hence reduces stress on the zonules during rotation. It is speculated that hydrodissection removes epithelial cells, forestalling subsequent contraction. However, one should be cautious not to overinflate the anterior chamber. The whole bag may subluxate from the increased pressure in the chamber. Injecting a small quantity of fluid every time and keeping the posterior lip of the incision depressed allow excessive fluid to flow out to maintain adequate pressure. Rotation is an added element in the armamentarium as it is believed to scrap the LECs and prevent capsule opacification.

In view of the compromised endothelium, every attempt should be made to avoid anterior chamber phacoemulsification. Closed-chamber phacoemulsification in the endocapsular plane using the step-down principle is safe in these cases. For sculpting, the phaco power should be set higher than usually used for a particular grade of cataract. This avoids an inadvertent push to the nucleus. To divide the nucleus, chop in situ and lateral separation is effective even in small-pupil phacoemulsification. It also prevents damage to weak zonules. To remove the divided fragments, the parameters, especially the aspiration flow rate and vacuum, should be kept low to prevent turbulence and surge in the chamber. Anticipating a fragile posterior capsule, it is mandatory to adhere to the principle of step-down technique.

Thorough cortex removal is advisable to minimize the risk of subsequent fibrosis. I would not hesitate to use bimanual I/A to ensure thorough cleanup. Every time I exit the eye, I inject cohesive viscoelastic material to prevent to-and-fro movement of the iris-lens diaphragm, maintaining a stable chamber.

In anticipation of capsule contraction, I would implant a PMMA Morcher CTR with a 13.0 mm diameter in the bag. The ring will keep the bag stretched and resist contraction.

A single-piece AcrySof IOL with a 6.0 mm optic and 13.0 mm total diameter (model SA30AT) is implanted in the bag through an injector. Contraction of the capsule is least common with acrylic IOLs, which are biocompatible and safe to use in eyes with a compromised BAB. Because of its tacky surface, the IOL optic sticks to the posterior capsule and prevents further migration of LECs. The haptics have superior residual memory to withstand compression forces.

Most important is to create a definitive large capsulorhexis from the initially large one. I call this an I & D (initial small and definitive large) capsulorhexis. To perform this maneuver, which is done after in-the-bag IOL implantation, the anterior capsule beyond the capsulorhexis is peeled so that the anterior capsule does not cover the IOL optic. I make sure a very thin strip of anterior capsule is left between the zonular insertion and the capsulorhexis margin in all quadrants. This leaves few LECs, reducing the contraction process. The I & D capsulorhexis also prevents the need to scrape the anterior capsule, which would otherwise be necessary to reduce the number of LECs.

A final postoperative photograph is taken to document the position of the IOL in the bag. This will be used as a baseline for early detection of IOL decentration.

Postoperative medication includes topical steroids in tapering doses for 2 months and nonsteroidal antiinflammatory drugs for 3 months help to stabilize the BAB. Weak cycloplegics such as tropicamide prevent inflammation and its sequeale, which may suppress epithelial cell activity.

The patient has frequent follow-ups to detect an active inflammatory process and suppress it. Videorecording at every visit helps detect and evaluate anterior capsule fibrosis as well as early IOL decentration. In addition, the endothelial specular count and IOP measurements must be obtained and the disc evaluated.

In these cases, the following must be avoided: massage after peribulbar anesthesia, can-opener capsulotomy, a capsulorhexis size smaller than the IOL optic, anterior chamber phacoemulsification, aggressive phacoemulsification parameters for endocapsular fragment removal, leaving cortical fibers in the capsule, and silicone or plate-haptic IOLs implantation.

© 2002 by Lippincott Williams & Wilkins, Inc.