July 2007

 

CATARACT/ IOL

 

Perspectives in Cataract and IOL Surgery

Surgical options for severe ectopia lentis in children


by Dennis S. C. Lam, M.D. and Srinivas K. Rao, FRCSEd

 

Dr. Lam is an internationally recognized surgeon, researcher, teacher, and clinician. He is a professor of ophthalmology and chairman of the Chinese University of Hong Kong. In this month’s column, Dr. Lam addresses the problem of subluxed lenses in children, which presents unusual surgical challenges. He describes some of the routine techniques for the management of this surgical challenge, and then some innovative techniques that he and his co-author have developed and utilized with success. Anybody who deals with cataract surgery in children will find this article to be of special interest and great utility.

I. Howard Fine, MD, Column Editor

 

 

Figure 1: Pupillary capture of IOL in a child after lensectomy and scleral fixation of an IOL for severe ectopia lentis.

Figure 2: Scleral fixation of a CTR through the capsular bag.

Figure 3: Secondary scleral fixation of CTR-IOL complex.

Source: Dennis S. C. Lam, M.D.

Ectopia lentis.

Source: Dennis S. C. Lam, M.D.

Despite the surgical challenge, subluxed lenses can result in good outcomes for children

Cataract surgery in children is considered to be technically more complex than in adults. Difficulties stem from the smaller eye size, lesser eye wall rigidity, increased tissue elasticity, and greater plastic uveal response to trauma and surgery. In pediatric eyes that have weakened zonules and subluxed lenses, these factors assume increased significance, and careful surgical planning and meticulous execution are required.

Stationary versus progressive zonule loss

The cause of the zonule loss and lens subluxation is important. In conditions like trauma or iatrogenic zonule loss during surgery, the problem is ‘stationary’ and unlikely to progress after surgery. Apart from the lost zonules, the remaining fibers tend to be healthy and support surgical manipulations. Once the IOL is placed in a stable position, it is quite likely that there will be no late problems. On the other hand, if the zonule loss and lens subluxation are due to ‘progressive’ conditions like Marfan’s syndrome, or homocysteinuria, then the residual zonules are also weakened and stretched. Surgical manipulations may weaken these zonules further, resulting in poor support for the IOL. Even if the IOL is well placed during surgery, shifting and subluxation can occur later due to continued zonule loss.

Scleral fixation may be the procedure of choice

If there is zonule loss involving fewer than two quadrants of the lens circumference, and the lens is minimally subluxed, then the use of a standard capsular tension ring (CTR) may suffice to restore capsular bag anatomy. This device can be implanted in the bag after an anterior capsulorhexis to provide lens support and facilitate easy removal of the lens material from the bag. Ideally, such a maneuver is best used in “stationary” zonule loss, where further changes in the zonular apparatus of the lens are not expected in the post-op period. If the lens is subluxed extensively, and there is already vitreous present in the anterior chamber necessitating an anterior vitrectomy, a complete lensectomy and scleral fixation of an IOL may be the procedure of choice.1 This certainly applies to complete lens dislocation, no matter if the lens is dislocated anteriorly to the anterior chamber or posteriorly to the vitreous cavity. This procedure works well, but up to 50% of the eyes develop post-op pupillary capture of the IOL (Figure 1).2 Although the pupillary capture is usually asymptomatic and can be corrected by conservative means, its long-term risk is not clearly defined.2 In addition, there is a loss of the functional compartmentalization of the anterior and posterior chambers; the procedure is best reserved for eyes with severe lens subluxation with vitreous herniation or dislocation.

Strategies for lens displacement

If the lens is displaced but an edge is seen in the pupillary area, and the stretched zonules do not allow the vitreous to herniate into the anterior chamber, then a surgical approach that will restore the capsular bag anatomy and avoid an anterior vitrectomy may be beneficial. Since advanced subluxation will seldom resolve with the use of a standard CTR, we have described the use of scleral fixation sutures to fixate the CTR (one suture above and one suture below the CTR) through the capsular bag during the primary procedure (Figure 2).3 With the availability of the Cionni variant of the CTR, however, the eyelets in of the ring are sutured to the sulcus, thereby dragging the subluxed bag back into position. Once this is done, the IOL can be placed in the capsular bag, the preferred location in children. The surgical details of using the modified CTR for patients with significant zonular loss have been well described by Robert J. Cionni, M.D., Medical Director, Cincinnati Eye Institute, Ohio. 4,5 Although this is a good approach, the efficacy of which has been described in previous reports,4-6 it is technically challenging to perform. The capsulorhexis must be of adequate size and should be positioned appropriately. If it is very large, especially in the meridians of zonule loss, the CTR tends to slip out of the bag. If it is too small or eccentric, then introducing the CTR into the bag tends to be difficult and the use of the Cionni eyelet to move the bag back into position may distort the capsular opening. The presence of the eyelet above the plane of the rhexis and its subsequent contact with the iris tissue is a matter for concern, especially in younger children whose uveitic reaction may be more severe.

An approach for moderate to severe ectopia lentis

We have used an alternative two-stage approach for cases with moderate to severe ectopia lentis in which a standard CTR alone is not adequate. Our preferred technique is to stain the anterior capsule with ICG (indocyanine green, Daiichi Sankyo, Inc., Tokyo) or VisionBlue (trypan blue ophthalmic solution, Dorc International, Zuidland, The Netherlands) under air; to create a small anterior capsulorhexis so that the CTR can be secured implanted at a later stage; to perform hydrodissection, phaco, and cortical clean-up; and to implant the CTR and then the IOL into the capsular bag during the first stage of the procedure. Subsequently, one to two months later, when capsular fibrosis has set in (Figure 3-1), the two arms (one after the other) of a 9-0 Prolene suture are passed ab externo through a paracentesis (Figure 3-2) at the cornea periphery, and guided out of the ciliary sulcus using one 25 and one 27 G needle. The ab externo surface markings on the sclera for the needle passages are 1.5 mm from the limbus and 1.5 mm apart (Figure 3-3). One of the Prolene needles passes above the CTR and bag (Figure 3-2), while the other passes through the bag and below the CTR (Figure 3-3). The knot is tied on the scleral surface and is rotated through the tract produced by the 25 G needle, usually with ease because of the adequate tract size. The knot is thus buried underneath the sclera, and no scleral flap is required (Figure 3-4). The same procedure is performed on the other side of the capsular bag as well (Figure 3-5) to ensure that the capsular bag–IOL complex is now securely fixated in both sides (Figure 3-6). We find that this two-stage approach is simpler, requires less manipulation, and can be performed even if the Cionni ring is not available. One important advantage is that we can use a smaller capsulorhexis to ensure a stable CTR during the first stage of the procedure. However, it does require a second surgical procedure, usually under general anesthesia. We have performed the procedure on five eyes thus far, with good outcomes, but larger scale studies would be required to assess the benefits of this technique.

In conclusion, pediatric subluxed lenses do pose a significant surgical challenge, but with currently available techniques and instrumentation, we have a variety of options for dealing with such eyes, which result in good outcomes.

Editors’ note: Drs. Lam and Rao have no financial interests related to the above comments.

References

1. Young AL, Agrawal R, Yuen HK, Ng JS, Lam DS, Fan DS. Options for Marfan’s syndrome. J Pediatr Ophthalmol Strabismus 2001; 38(5):261. 2. Lam DS, Ng JS, Fan DS, Chua JK, Leung AT, Tham CC. Short-term results of scleral intraocular lens fixation in children. J Cataract Refract Surg 1998; 24(11):1474-1479. 3. Lam DS, Young AL, Leung AT, Rao SK, Fan DS, Ng JS. Scleral fixation of a capsular tension ring for severe ectopia lentis. J Cataract Refract Surg 2000; 26(4):609-612. 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(10):1299-1306. 5. Cionni RJ, Osher RH, Marques DM, Marques FF, Snyder ME, Shapiro S. Modified capsular tension ring for patients with congenital loss of zonular support. J Cataract Refract Surg 2003; 29(9):1668-1673. 6. Konradsen T, Kugelberg M, Zetterstrom C. Visual outcomes and complications in surgery for ectopia lentis in children. J Cataract Refract Surg 2007; 33(5):819-824.

ABOUT THE AUTHORS

Dennis S. C. Lam, M.D., is chairman, Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong; He can be reached at 852-2632-2878 or dennislam8@cuhk.edu.hk.

Srinivas K. Rao, FRCSEd., is Director,, Darshan Eye Clinic, Chennai, India, and Head, Cornea and Refractive services, Rajan Eye Care, Chennai, Tamil Nadu, India, and Visiting Professor, Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong. He can be reached at (91) 4443500003 or srinikrao@gmail.com.

Surgical options for severe ectopia lentis in children Surgical options for severe ectopia lentis in children
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