Cataract Surgery
When Capsular Support Is Poor

A modified CTR is effective with these patients.

Boris Malyugin, MD, PHD

A prerequisite for modern cataract surgery is a healthy status of the natural lens supporting system. Therefore, patients with generalized zonular weakness or extensive local zonular defects present significant challenges.

Trauma, pseudoexfoliation syndrome, glaucoma, high myopia, hereditary systemic diseases (Marfan's and Weill-Marchesani syndromes, homocystinuria, etc) are among the most common conditions leading to zonular apparatus compromise. In these patients, the surgeon can expect increased risk of capsular tears, vitreous prolapse and IOL instability.

Here, I will discuss the procedure — and the specific devices — that I have found to be the most effective in performing cataract surgery on patients with serious zonular issues.

The Limitations of Iris Retractors

Different devices have been designed to facilitate cataract surgery in patients with zonular dialysis. For instance, flexible iris retractors can be used to enlarge the pupil and simultaneously to support the capsular bag in the presence of extreme zonular weakness. However, because of their short and flexible hooked ends, iris retractors tend to slip off and in some cases tear the anterior capsulorhexis.

Specially designed capsule retractors made of titanium or plastic, including the capsule support system manufactured by Duckworth and Kent Ltd. (Hertfordshire, United Kingdom) and MicroSurgical Technology capsule retractors (MST, Seattle) have hooked ends, which are elongated enough to support the peripheral capsular fornix and do not tear the rhexis.

These devices are capable of functioning in the role of artificial zonules, fixating the whole capsular bag to the limbal area. They are thus able to stabilize the bag during phacoemulsification and do not complicate cortical cleanup. Also, the effect is temporary, as all of them have to be removed at the completion of the surgical procedure.

Capsular Tension Segments

Capsular tension segments (I.Ahmed, 2001), Assia Anchor (E.Assia, 2005) and T-shaped hooks (R.Yamaguchi, 2008) have the main advantage of minimizing the surgical trauma to the already compromised residual zonules (Figure 1). These devices support the capsular bag during the surgery and prevent its dislocation postoperatively. The main disadvantage of these devices is that they can create only focal support of the capsular bag and do not totally restore its equator shape. That is why in many cases their combination with conventional or modified capsular tension rings (CTRs) is mandatory.

Figure 1. Different capsular supporting devices used in patients with zonular instability and or dehiscence.

Capsular Tension Rings

Capsular tension rings were introduced into clinical practice in the 1990s. They are extremely helpful in stabilizing the crystalline lens during cataract surgery and in reducing the likelihood of intraoperative complications. CTRs are used to maintain the circular contour of the capsular equator during surgery through stretching of the capsular bag and distributing forces equally over all zonules. Also, they prevent vitreous prolapse into the anterior chamber and capsule damage during irrigation/aspiration.

CTRs are manufactured in different sizes to be used for pediatric, emmetropic and also the large (myopic) eyes that may have a larger capsular bag diameter. While selecting the size of the ring, the surgeon must keep in mind also the age of the patient, axial length of the eye, elasticity of the capsule, and the strength of the capsular support that the patient needs.

The downside of CTR is the technical complication of the irrigation-aspiration phase of the surgery. This is because of trapping of the cortical material at the equator of the capsular bag, which makes the aspiration process much more difficult. Keeping this fact in mind, the surgeon should consider delaying CTR insertion until after the cortex has been removed. In some cases, when early implantation of the CTR is justified, it is possible to increase the efficiency of the cortex removal by its tangential stripping and utilizing the bimanual irrigation-aspiration systems.

Currently, indications for conventional CTRs include zonular instability and rupture during surgery, as well as inherent or acquired zonular weakness. However, in cases of progressive or advanced zonulopathy, standard CTRs are unlikely to provide the capsular support needed. They are also not able to prevent progressive zonular loss and capsular decentration. A high risk exists that the IOL will be dislocated late postoperatively.

The Cionni CTR

To address the cases with profound zonular weakness, Robert Cionni, MD, modified the standard CTR, adding the fixation eyelet attached to the central portion of the ring. This eyelet allows the ring to be sutured to the sclera, providing intraoperative support during phacoemulsification. The Cionni-modified CTR (Morcher GmbH, Germany) is a useful tool, which can be recommended for patients with zonular dialysis exceeding the area of three clock hours. This device is available in different versions, with one or two fixation elements (Figure 2).

Figure 2. Different variations of the Cionni modified capsular tension ring.

Most surgeons implant the Cionni device manually through the main cataract corneal incision utilizing forceps. The use of injectors is much less common. That is because the fixation element attached to ring does not allow the device to be fully retracted inside the injector tube.

The Malyugin Injector-friendly CTR

The Malyugin modified Cionni CTR (Morcher Type 10G, Morcher GmbH, Germany) is the newest endo-capsular-supporting device. The basic idea of developing it was in making the device injector-friendly. This was achieved by moving the fixation element to the ring's tip (Figure 3). As a result, the modified CTR became completely retractable into the injector tube, subsequently allowing it to be used through 2.2-mm and smaller incisions.

Figure 3. Malyugin modified capsular tension ring (CTR).

The new CTR addresses the difficulties of microincisional cataract surgery in patients with a large zonular dialysis or zonular weakness by centering the subluxated lens and securing it to the scleral wall. During implantation, the curved portion of the Malyugin CTR slides along the equator of the capsular bag during its injection. Thus, the risk of perforating the capsular fornix with the tip of the CTR is eliminated.

Surgical Technique

Following is the step-by-step surgical technique for performing the Malyugin modified CTR procedure:

Surgical technique with the Malyugin CTR and MST capsular hooks is illustrated in a patient with Marfan's syndrome (Figure 4).

Figure 4. Eye of a patient with Marfan's syndrome.

After creating a clear corneal incision, a capsulotomy is initiated with the sharp bent needle. Micro capsulorhexis forceps are used to grasp the flap and to tear the capsule in the circular manner (Figure 5 a,b).

Figure 5 a,b. Continuous curvilinear capsulorhexis

In many cases, capsular folds and lens instability during the capsulorehxis can be observed, which presents the additional evidence of significant zonular pathology. In these situations, I prefer stabilizing the capsular bag with the help of capsular hooks (MicroSurgical Technology Inc., Redmond, Wash.). The hooks are inserted one by one through corneal paracentheses, catching the capsulorhexis edge and temporary fixating the capsular bag to the limbus (Figure 6 a,b).

Figure 6 a,b. Capsular hook-assisted capsulorhexis

After finishing capsulorhexis in traumatic cataract cases, I go directly to the modified CTR implantation. However, in patients with Marfan's syndrome, the situation is different because of the lens hypoplasia and reduced equatorial diameter of the capsular bag.

With these patients, a two-step lens removal approach is preferable. First, partial aspiration of the lens bag content is performed to debulk the lens and expand the capsular bag (Figure 7). Then, the modified CTR is implanted and sutured to the sclera followed by irrigation-aspiration of the residual lens material.

Figure 7. Two capsular hooks are stabilizing the bag, while partial aspiration of the lens material is being performed.

The Malyugin modified CTR is retracted into the injector cartridge. A needle is passed through the eyelet to fixate it with a 9/0 polypropylene suture. During implantation, the injector is positioned in the center of the anterior chamber. By pushing the plunger, the surgeon slowly inserts the ring directly under the anterior capsule into the capsular bag (Figure 8 a,b).

Figure 8 a,b. Malyugin modified CTR (Mocrcher GmbH) is injected into the capsular bag. CTR can be visualized through the transparent plastic injector tube.

To prevent damaging of the residual zonules, it is necessary to inject the ring in the direction of the zonular defect. During injection, the curved fixation element safely slides along the equator of the capsular bag without any risk of damaging it. The trailing end of the device is guided under the fixation element and released from the injector plunger.

Using the reversed Sinskey hook, the CTR is rotated so as to place the fixation element directly in the center of the zonular defect (Figure 9 a). The fixation element is guided out of the bag through the caspulorhexis opening with the hook and positioned on the anterior surface of the anterior capsule (Figure 9 b).

Figure 9 a,b. Modified CTR rotation with the hook.

A fornix-based conjunctival flap is created with the scissors, followed by gentle cautery of the episcleral vessels. The needle is passed through the ciliary sulcus with the ab interno approach (Figure 10 a). After needle externalization, it is then fixated to the superficial scleral layers in a zigzag fashion with 4-5 bites, followed by tying the double knot (Figure 10 b). The conjunctiva is closed with two paralimbal 8/0 Vicryl interrupted sutures.

Figure 10 a,b. 9/0 Prolene suture is passed through the ciliary sulcus and fixated to the superficial scleral layers.

Summary of the Malyugin Modified CTR Advantages:

► Fully retractable inside the injector — easy atraumatic insertion. ► Can be implanted through 2.2-mm MICS incision. ► Curved portion of the CTR slides along the equator of the capsular bag eliminating the risk of perforating the capsular fornix. ► Allows the loose eccentric capsules to be recentered and secured achieving safe endocapsular implantation and long-term stability of the capsular bag.

After suturing the CTR to the sclera, bimanual irrigation and aspiration of the lens is performed (Figure 11 a,b). Following the capsular bag content evacuation, a foldable acrylic IOL is injected into the capsular bag. The lens is usually implanted into the anterior chamber to avoid the stress the leading haptic may cause to the capsular fornix during injection. It is then gently guided through the pupil inside the bag (Figure 12 a, b).

Figure 11 a,b. Irrigation-aspiration of the cortical material with the bimanual I/A handpiece set (Duet system, MST).

Figure 12 a, b. Hydrophobic acrylic IOL implanted into the capsular bag. Both IOL haptics are positioned with the help of the micro-hook inserted through the paracentheses.

Corneal wounds are closed with 10/0 nylon suture to achieve watertightness if necessary. At the end of the procedure, the stable positioning of the “capsular bag/IOL” complex is verified.

Positive Results Achieved

Our current experience with the Malyugin modified CTR is established in 27 patients with severe acquired and hereditary lens subluxations. From this cohort, 19 patients were diagnosed with Marfan's syndrome. The mean age of this group was 12.8+/-6.2 years. There were followed for 22.5/±4.7 months postoperatively.

As a result of the surgery, mean BCVA improved to 20/30. No major complications were observed during and after the procedures, IOP was within the normal range. PCO was the most frequent finding postoperatively; it occurred in nine eyes, five of which required YAG capsulotomy. Capsular bag and IOL central position were verified with ultrasonic biomicroscopy.

Conclusions

In modern cataract surgery, a variety of forces must be applied to the capsular bag and zonules during lens extraction, nuclear rotation and IOL implantation. Accordingly, the status of the zonular apparatus determines how smooth the performance of phacoemulsification will be. Compromised zonules still present significant challenges and raise the risk of intra- and postoperative complications that can threaten long-term IOL stability.

Conventional devices provide numerous benefits to surgeons managing challenging cataracts with weakened zonules. In many cases they are very useful in stabilizing crystalline lens during cataract surgery and reducing the likelihood of intraoperative complications. However, in cases of progressive or advanced zonulopathy, standard CTRs are unlikely to provide the capsular support needed. They are also not able to prevent progressive zonular loss and capsular decentration. A high risk exists that the IOL will be dislocated postoperatively.

The ongoing development of endocapsular devices allows for removal of cataracts in complicated cases with weak or absent zonules as well as providing fixation of the capsular bag to the sclera.

Based on the achieved results, we came to the conclusion that the use of the Malyugin modified CTR provides favorable functional and anatomical results in patients with Marfan's Syndrome. OM

General References

1. 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.
2. Cionni R, Osher R. Endocapsular ring approach to the subluxed cataractous lens. J Cataract Refract Surg. 1995;21:245-249.
3. Cionni R, Osher R. Management of profound zonular dialysis or weakness with a new endocapsular ring designed for scleral fixation. J Cataract Refract Surg. 1998;24:1299-1306.
4. Moreno-Montanes J, Sainz C, Maldonado MJ. Intraoperative and postoperative complications of Cionni endocapsular ring implantation. J Cataract Refract Surg. 2003;29:492-497.
5. Malyugin B, Golovin A. Long-Term Results of Cataract Surgery in Patients With Traumatic Zonular Dialysis and Mydriasis. Paper presented at: ASCRS/ASOA Symposium on Cataract, IOL, and Refractive Surgery; March-April, 2011; San Diego, California.
6. Merriam JC, Zheng L. Iris hooks for phacoemulsification of the subluxated lens. J Cataract Refract Surg. 1997;23:1295-1297.
7. Ahmed I, Kranemann C, Crandall A. Capsular hemi-ring: next step in effective management of profound zonular dialysis. Paper presented at: ASCRS/ASOA Symposium on Cataract, IOL, and Refractive Surgery; April 12-13, 2003; San Francisco, California.
8. Jahan FS, Mamalis N, Crandall AS. Spontaneous late dislocation of intraocular lens within the capsular bag in pseudoexfoliation patients. Ophthalmology. 2001;108:1727-1731.
9. Chang DF. Prevention of bag-fixated IOL dislocation in pseudoexfoliation (letter). Ophthalmology. 2002;109:5-6.

Boris Malyugin, MD, PhD, is professor of ophthalmology, S. Fyodorov Eye Microsurgery Complex State Institution, Moscow.