June 2010

 

CATARACT/ IOL

 

Should CTRs be implanted in every PXF patient?


by Richard S. Hoffman, M.D., I. Howard Fine, M.D., and Mark Packer, M.D.

 

Capsular tension rings (CTRs) are one of the most important adjunctive surgical devices in our armamentarium and have enhanced the safety of performing phacoemulsification in the presence of pseudoexfoliation. However, controversy still exists as to the timing of CTR implantation during the cataract procedure, and whether these devices should be implanted only when evidence of zonular stability becomes apparent or implanted routinely in all pseudoexfoliation patients. In our practice, we believe that early implantation of the CTR may help to enhance zonular stability during the introduction of phacoemulsification stresses and prevent subsequent zonular complications. The apparent increasing frequency of late IOL/capsular bag subluxations in pseudoexfoliation patients many years after their routine cataract procedures has prompted us to now use CTRs routinely in most of our pseudoexfoliation patients. This issue’s column presents a discussion of why we may want to implant these devices more frequently even in routine pseudoexfoliation cases.

Richard Hoffman, M.D., Column Editor

 
Figure 1: Morcher Capsular Tension Ring

Figure 2: Subluxed IOL/capsular bag. Note edge of optic, edge of bag equator, and IOL haptic. No CTR is in place

Figure 3: Subluxed IOL/capsular bag/CTR undergoing scleral fixation of CTR utilizing a double-armed 9-0 prolene suture passed through a distant micro-incision. The prolene suture needle is docked with a 27-gauge needle that is passed through the sclera and through the capsular bag inside of the CTR. An iris hook facilitates visualization Source: Richard S. Hoffman, M.D.

Cataract surgery in the presence of pseudoexfoliation (PXF) of the lens presents surgeons with many challenges. In addition to a higher incidence of glaucoma, these patients have loss of zonular integrity occasionally associated with lens subluxation and pupils that dilate poorly. Modern surgical techniques and adjunctive devices have allowed for most cases of PXF to proceed routinely. Small pupils can be addressed with pupil stretching, iris hooks, pupil expansion rings, and viscoadaptive ophthalmic viscosurgical devices. In addition, weakened zonules can be supported and protected by utilizing chopping over grooving techniques and implanting capsular tension rings (CTRs) prior to the introduction of phacoemulsification stresses.

When placed within the capsular bag, a CTR (Figure 1) provides several advantages. It prevents the concentration of forces on individual zonules by distributing all forces applied to any point on the capsulorhexis to the entire zonular apparatus. It also keeps the bag on stretch throughout the procedure, allowing for greater safety during all intraocular manipulations.1 There was hope that the continuous pressure of the ring against the capsular fornices would act to bolster any residual zonular traction on the capsule and counter the forces of constriction of the capsulorhexis following metaplasia and fibrosis of the lens epithelial cells. However, several reports of significant capsule phimosis despite ring placement in PXF cases2,3 reveal that the ring may not prevent this complication and underscores the need for a large capsulorhexis in these patients. Most surgeons are currently implanting CTRs only when evidence of zonular instability develops during phacoemulsification. Increasing reports of late IOL/capsular bag subluxation (Figure 2) in PXF patients4,5 necessitate reevaluating whether CTRs should be placed on an as-needed basis or implanted in every patient with PXF. Why implant a CTR in every PXF patient? Although the placement of a CTR in PXF does not eliminate the late complication of IOL/capsular bag subluxation6, it may reduce the incidence or delay the occurrence of this complication, and most importantly, it may facilitate future treatment of these patients when symptomatic subluxation does develop. The treatment options for subluxated IOL/capsular bags range from IOL exchange to intraocular fixation to the iris or sclera.7 Exchange of these large IOL/bag complexes necessitates removal through larger incisions and may generate the associated complications that can develop from expected vitreous loss. Although iris fixation is an option, the seclusion of the IOL haptics within the capsular bag and the inability to prolapse the IOL optic through the pupil for stabilization during iris fixation makes this approach difficult and prolonged. It is because of these limitations that scleral fixation is perhaps the simplest and most straightforward method for dealing with IOL/capsular bag subluxation.

Transscleral fixation of the capsular bag to the ciliary sulcus can be easily accomplished through micro-incisions utilizing suture looping through the capsular bag and around the CTR8 (Figure 3). If a CTR was not implanted during the primary procedure, secondary implantation of a CTR many years following the initial surgery can be difficult in the presence of a fibrosed capsular bag and severe loss of zonular integrity. Fixation of the IOL haptics to the sclera (through the capsular bag) and recentration can still be achieved without a CTR but necessitates that the IOL haptics be oriented in the proper meridian for four-point scleral fixation. For instance, a severe temporally dislocated IOL/capsular bag complex without a previously placed CTR, with the haptics oriented at 12 and 6 o’clock, would be much more difficult (but not impossible) to fixate and reposition nasally than if the haptics were oriented at the 3 and 9 o’clock meridian. If a CTR was implanted at the time of the initial surgery, haptic orientation of the IOL would be inconsequential since the CTR creates 360 degrees of potential fixation points for scleral fixation.

CTRs are perhaps one of the simplest and most powerful tools for avoiding intraoperative complications and preventing extension of complications once they develop during cataract surgery. Although the current standard may be to not implant these devices in routine PXF eyes without evidence of zonular weakness, we may find in the near future that an abundance of late IOL/capsular bag subluxations in our increasingly aging PXF patients may be rectified more straightforwardly if a CTR was placed at the time of the initial surgery. We are currently placing CTRs in all of our pseudoexfoliation patients with the hope that late post-op complications such as capsule phimosis and subluxation may be delayed, and when subluxation of the capsular bag/IOL complex does develop, it can be more easily addressed with scleral fixation of the previously placed CTR.

References

1. Bayraktar S, Altan T, Kucuksumer Y, Yilmaz OF. Capsular tension ring implantation after capsulorhexis in phacoemulsification of cataracts associated with pseudoexfoliation syndrome. Intraoperative complications and early postoperative finding. J Cataract Refract Surg 2001; 27:1620-1628.

2. CW, Eckhardt M. Complete capsulorhexis opening occlusion despite capsular tension ring implantation. J Cataract Refract Surg 1999; 25:1013-1015.

3. Waheed K, Eleftheridas H, Liu C. Anterior capsular phimosis in eyes with a capsular tension ring. J Cataract Refract Surg 2001; 27:1688-1690.

4. Masket S, Osher RH. Late complications with intraocular lens dislocation after capsulorhexis in pseudoexfoliation syndrome. J Cataract Refract Surg 2002; 28:1481-1484.

5. Jehan FS, Mamalis, Crandall AS. Spontaneous late dislocation of intraocular lens within the capsular bag in pseudoexfoliation patients. Ophthalmology 2001; 108:1727-1731.

6. Scherer M, Bertelmann E, Rieck P. Late spontaneous in-the-bag intraocular lens and capsular tension ring dislocation in pseudoexfoliation syndrome. J Cataract Refract Surg 2006;32:672-675.

7. Ahmed II, Chen SH, Kranemann C, Wong DT. Surgical repositioning of dislocated capsular tension rings. Ophthalmology 2005;112:1725-1733. 8. J, Heras H, Fernandez-Hortelano A. Surgical treatment of a dislocated intraocular lens-capsular bag-capsular tension ring complex. J Cataract Refract Surg 2005;31:270-273.

Should CTRs be implanted in every PXF patient? Should CTRs be implanted in every PXF patient?
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