Hyperguides

Ophthalmology / Cataract

Interpseudophakos/Interlenticular Opacification

Joel K. Shugar, MD, MSEE
Article


Interpseudophakos/interlenticular opacification (IPO/ILO) has emerged as a late complication of piggyback IOL implantation.1-4 IPO/ILO is characterized by ingrowth of lens epithelial cells (LECs) between the IOLs, 1 to 3 years following piggyback implantation. Interpseudophakos Elschnig pearl ingrowth (IPO-E) is most common and is associated with a late hyperopic shift in both PMMA and acrylic lens pairs. A-type LEC ingrowth (IPO-A), clinically presenting with a fibrocellular appearance similar to anterior capsular opacification, has also been observed.5

Incidence

IPO/ILO has been observed in eyes with piggybacked PMMA IOLs and documented in anecdotal reports of eyes with piggybacked silicone IOLs. However, IPO/ILO most commonly occurs in eyes implanted with piggybacked acrylic IOLs; if possible, alternate optic materials should be selected. The incidence of IPO/ILO appears to correlate directly with the biocompatibility of the optic material.6 For piggyback implantation, RMX-3 silicone material (AA4204VL, Staar Surgical) is preferred to more biocompatible materials such as acrylic.

Harry Grabow, MD, first reported piggyback bag/bag placement of plate-haptic silicone lenses, with the plates placed perpendicularly.7 After having explored almost every conceivable variant of piggyback implantation, including heterogeneous plate-haptic/loop, I am currently using Dr. Grabow's technique for eyes requiring more than 34 D total IOL power.8 There is approximately a 0.5-mm central "dimple" defining the contact zone between the IOLs, which I have found to be without clinical significance. A 6-mm capsulorrhexis diminishes the force compressing the optics together and the size of this dimple.

Lenses consisting of RMX-3 silicone material have the lowest index of refraction and are the thickest foldable IOLs, and therefore minimize the contact zone and maximize the distance between the peripheries of the optics (which both serve to decrease the incidence of IPO/ILO). Because the crystalline lens in eyes with nanophthalmos is larger than in normal eyes, there is sufficient room in the bag for two IOLs, even two IOLs made of RMX-3, maximizing the postoperative dimensions of the angle relative to bag/sulcus implantation.

Another significant factor in the incidence of IPO/ILO is the relationship between the capsulotomy margin and the IOL optics. IPO/ILO is most frequently observed in cases in which the anterior capsulotomy margin overlaps the anterior optic margin or comes in contact with the interface between the lenses. To avoid late IPO/ILO, two looped posterior chamber IOLs should not be placed together in the capsular bag in conjunction with an ordinary sized capsulorrhexis that overlaps the margin of an anterior IOL. I developed the large capsulorrhexis strategy for looped lens pairs, in which a 6.25-mm to 6.75-mm capsulorrhexis is created and both haptic pairs are placed together in the capsular bag. A relative haptic orientation between the IOLs should be chosen to maximize clearance of the anterior capsular remnant from the anterior optic and peripheral interface between the IOLs, but perpendicular alignment best supports the zonule, acting like a capsular tension ring. Creating a large capsulorrhexis that extends close to the anterior zonular insertion can be technically challenging in these small eyes. Initially, if a large capsulorrhexis cannot be created safely, an alternate strategy can be used. Johnny Gayton, MD, and Samuel Masket, MD, have suggested placing the anterior chamber IOL in the ciliary sulcus in an attempt to avoid late IPO/ILO. Kenneth Rosenthal, MD, suggested a variant of this strategy in which a 30-D AcrySof IOL (Alcon, Ft. Worth, Texas) is placed in the bag and the eye is allowed to heal for 6 months, at which time any remaining ametropia can be corrected with a secondary IOL in the sulcus.9 However, bag placement of both haptic pairs minimizes pigment dispersion and maximizes the postoperative anterior chamber depth and angle dimensions. Therefore, when a large capsulorrhexis cannot be created initially, David Chang, MD, has suggested enlarging the capsulorrhexis after IOL implantation to fixate both haptic pairs in the bag.10

Follow-up

The preoperative consultation should include thorough discussion of the potential complications unique to patients with nanophthalmic eyes, including late IPO/ILO. Also, a clinician should emphasize the need for periodic long-term postoperative follow-up. Attentive follow-up of polypseudophakic eyes is important. Early cases may be treated with a YAG laser with the laser defocus set at 0, by meticulously focusing on the interface at the proximal margin of the IPO/ILO ingrowth.11 Once a gas bubble is created, I attempt to continually work within the bubble as material is removed from the peripheral interface between the lenses. IPO/ILO that is present centrally is treated last, using the gas bubble generated by the YAG laser to separate the lens optics at the site of the next YAG shot to avoid pitting of the lenses. Attempted surgical aspiration of the LECs from acrylic lenses leaves a densely adherent acellular protein that is difficult to remove, often necessitating IOL exchange.12 Dense opacification between the central interfaces requires a late IOL exchange in an increasingly large number of investigators' cases.

References

  1. Shugar JK, Schwartz T. Interpseudophakos Elschnig pearls associated with late hyperopic shift: A complication of piggyback posterior chamber intraocular lens implantation. J Cataract Refract Surg. 1999;25:863-867.


  2. Gayton JL, Apple DJ, Peng Q, et al. Interlenticular opacification: A clinicopathological correlation of a new complication of piggyback posterior chamber intraocular lenses. J Cataract Refract Surg. 2000;26:330-336.


  3. Shugar JK, Keeler S. Inter-pseudophakos intraocular lens surface opacification as a late complication of piggyback acrylic posterior chamber intraocular lens implantation. J Cataract Refract Surg. 2000;26:448-455.


  4. Stasiuk R. Interface Elschnig pearl formation with piggyback implantation (letter). J Cataract Refract Surg. 2000;26:158-159.


  5. Shugar, JK. Inter-pseudophakos opacification. Invited Discussion at the American Academy of Ophthalmology Meeting. Orlando, Fla; October 25, 1999.


  6. Shugar JK. Piggyback IOL implantation: Fifty-seven month experience. Presented at the American Society for Cataract and Refractive Surgery Annual Symposium. Boston, Mass; May 20, 2000.


  7. Grabow HB. Polypsuedophakia. Presented at the American College of Eye Surgeons Annual Meeting. Orlando, Fla; 1996.


  8. Shugar JK. Interpseudophakos opacification and interlenticular membrane formation. Invited presentation at the American Society for Cataract and Refractive Surgery Annual Symposium, PCO Symposium. Boston, Mass; May 23, 2000.


  9. Written communication. The American Society of Cataract and Refractive Surgeons Internet Cataract Discussion Group. May 1999.


  10. Chang D. Achieving a large capsulorhexis for piggyback IOLs. Presented at the Symposium on Cataract, IOL, and Refractive Surgery at the American Society for Cataract and Refractive Surgery Annual Symposium. Boston, Mass; May 2000.


  11. Shugar JK. YAG laser lysis of interpseudophakos opacification. Presented at the American Society for Cataract and Refractive Surgery Annual Symposium, ASCRS/ALACCSA Symposium. Boston, Mass; May 20, 2000.


  12. Werner L, Shugar JK, Pandey S, Escobar-Gomez M, Visessook N, Apple DJ. Opacification of piggyback IOLs associated with an amorphous material attached to their surfaces. J Cataract Refract Surg. 2000;26:1612-1619.