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From the editor

Visual axis opacification after pediatric intraocular lens implantation

Kohnen, Thomas MD

Journal of Cataract & Refractive Surgery: August 2001 - Volume 27 - Issue 8 - p 1141-1142
doi: 10.1016/S0886-3350(01)01063-X
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The surgical treatment of pediatric cataracts with intraocular lenses (IOLs) remains a challenge for all ophthalmic surgeons. The surgical difficulties are related to such factors as scleral rigidity, anterior lens capsule elasticity, and the small size of the young eye.1 Even with a perfectly performed extracapsular cataract extraction and posterior chamber IOL implantation, postoperative complications can occur. These include increased inflammation, secondary glaucoma, refractive instability because of the growing pediatric eye, and early and severe visual axis opacification (VAO). The VAO results from the aggressive growth of fibrous material along the posterior surface of the iris, the capsule remnants, and the anterior vitreous face that tends to develop in the healing young eye. Visual axis opacification is a major complication of congenital cataract procedures because it can quickly cause irreversible amblyopia. The question of how we can effectively minimize or eliminate this problem must be addressed.

Surgical tools and IOLs are now available that reduce the rate of posterior capsule opacification (PCO) to single-digit percentages in extracapsular cataract surgery in adults with intact posterior capsules and posterior chamber IOLs.2 Based on their analysis of 5416 pseudophakic human eyes obtained postmortem, Apple et al.2 recommend the following to prevent PCO: hydrodissection-enhanced cortical cleanup; in-the-bag IOL fixation; a continuous curvilinear capsulorhexis (CCC) diameter of moderate size, slightly smaller than that of the IOL optic; a biocompatible IOL to reduce stimulation of cellular proliferation; maximum contact between the IOL optic and the posterior capsule; angulated haptics; “bioadhesive” biomaterial to create a “shrink wrap”; and IOLs with a squared, truncated optic edge.

Leaving the posterior capsule intact after IOL implantation in children predisposes to an unacceptably high rate of secondary cataract formation.3 The above factors are therefore not sufficient to prevent PCO. Other surgical maneuvers to maintain a clear visual axis after pediatric posterior chamber IOL implantation have been tried; eg, primary posterior capsulotomy, epilenticular IOL implantation with pars plana lensectomy, secondary pars plana or limbal capsulotomy and/or anterior vitrectomy, primary posterior CCC with or without anterior vitrectomy, and primary posterior CCC and posterior optic capture of a capsular-bag-fixated IOL with or without anterior vitrectomy.

Recent studies suggest that a primary opening in the posterior capsule is a required step in congenital IOL surgery to prevent VAO. It is also necessary to perform an anterior vitrectomy to maintain a clear visual axis. However, long-term complications such as vitreous or macular changes or retinal detachment several decades after anterior vitrectomy performed during pediatric IOL surgery have not been studied extensively. It might be desirable to avoid this surgical step.

One advantage of posterior optic capture described by Gimbel and DeBroff4 might be the prevention of VAO without an anterior vitrectomy. In this issue, Vasavada and coauthors report on optic capture with or without anterior vitrectomy in children between 5 and 12 years of age. With a 5.25 mm optic-captured IOL, they found that the visual axis remained clear in all eyes with an anterior vitrectomy but in only 30% of eyes without an anterior vitrectomy. Visual axis opacification was described as “reticular fibrosis of the anterior vitreous phase.” Although visual acuity and high-contrast acuity were almost the same in both groups, low-contrast sensitivity was better in the vitrectomized eyes, a finding that should be examined.5

Surgeons have a tremendous responsibility when performing pediatric cataract extraction. The best surgical option should be used in cases of congenital cataract because the patients will be affected by this procedure for their entire lives. As VAO can be a major problem of in-the-bag IOL fixation, which otherwise provides good results, we must invest time and research sources for a solution. Vasavada and coworkers have helped improve our knowledge of the optimal treatment of pediatric cataracts.

References

1. Zetterström C. Intraocular lens implantation in the pediatric eye (editorial). J Cataract Refract Surg 1997; 23:599-600
2. Apple DJ, Peng Q, Visessook N, et al. Eradication of posterior capsule opacification: documentation of a marked decrease in Nd:YAG laser posterior capsulotomy rates noted in an analysis of 5416 pseudophakic human eyes obtained postmortem. Ophthalmology 2001; 108:505-518
3. Buckley EG, Klombers LA, Seaber JH, et al. Management of posterior capsule during pediatric intraocular lens implantation. Am J Ophthalmol 1993; 115:722-728
4. Gimbel HV, DeBroff BM. Posterior capsulorhexis with optic capture: maintaining a clear visual axis after pediatric cataract surgery. J Cataract Refract Surg 1994; 20:658-664
5. Birch EE, Swanson WH, Stager DR, et al. Outcome after very early treatment of dense congenital cataracts. Invest Ophthalmol Vis Sci 1993; 34:3687-3699
© 2001 by Lippincott Williams & Wilkins, Inc.