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Consultation section

September consultation #5

Dick, Burkhard H. MD, PhD

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Journal of Cataract & Refractive Surgery: September 2013 - Volume 39 - Issue 9 - p 1447-1448
doi: 10.1016/j.jcrs.2013.07.010
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Six months after pIOL implantation, 3 issues must be addressed in the left eye; that is, the halos, pigment deposits, and subjective complaints regarding near vision (although the UNVA is J1). Brimonidine is well tolerated and of moderate success in decreasing halos by reducing relative pupil mydriasis at scotopic illumination levels. Application of 1 drop 20 minutes before activities in dim-light conditions or at night is recommended.1 An attempt to reduce the use of brimonidine is advisable because photic phenomena usually decrease over time.

Pigment flow is undesired but unavoidable if the PC is the site of pIOL implantation. In my experience, chafing of the iris in this case is moderate and self-limiting. Pigmentation observed in the early postoperative period returns to the preoperative level after 1 to 1½ years. My nearly 3-year follow-up and recent clinical trials did not confirm previous concerns of a long-term risk for chronic pigment-dispersion glaucoma.2 The pigment on the pIOL could be caused by the greater vaulting.

This pIOL is relatively large and has broad iris contact. An ideal vault is approximately 500 μm. However, greater vaulting values are also welcome. The actual vault is within the recommended range of 300 to 600 μm. Excessive vaulting (>1000 μm) is of concern because it leads to angle crowding and may result in angle closure or synechiae formation. There will be continuous axial crystalline lens growth of approximately 25 μm per year. Recent observations showed a consistent reduction in the central vault over a 10-year period.3 Because this pIOL has a slightly high vault, observation rather than pIOL exchange is the best option. A pIOL exchange for a smaller version has, in addition to other negative aspects, the potential to result in a low vault (<150 μm), causing pIOL contact with the crystalline lens, which increases the risk for cataract formation over time. A minimum central vault of 250 μm seems to be necessary to ensure a sufficient and safe vault over time. Therefore, in the correction of myopia it is best to choose a pIOL length for the greatest possible postoperative central vault.

Accommodation might be impaired in the early period after pIOL implantation. The accommodative response can be transiently impaired in part by contact between the pIOL fixation and the ciliary body–zonule. Usually the pIOL haptics are located in the ciliary sulcus. Sometimes, the tip of the haptics rest adjacent to the zonule and exert pressure on the ciliary body instead of being in a more upward tip direction in the ciliary sulcus underneath the iris. The V4 Visian pIOL is slightly more prone to this because of the greater vault with a more posterior direction of the haptics and less directional tendency upward. This temporary accommodative dysfunction after implantation of this pIOL was reported in 2006.A Accommodation usually recovers gradually over time in myopic eyes; therefore, my advice is to wait.4

References

1. Marx-Gross S, Krummenauer F, Dick HB, Pfeiffer N. Brimonidine versus dapiprazole: influence on pupil size at various illumination levels. J Cataract Refract Surg. 2005;31:1372-1376.
2. García-Feijoó J, Jiménez Alfaro I, Cuiña-Sardiña R, Méndez-Hernandez C, Benítez del Castillo JM, García-Sánchez J. Ultrasound biomicroscopy examination of posterior chamber phakic intraocular lens position. Ophthalmology. 2003;110:163-172.
3. Schmidinger G, Lackner B, Pieh S, Skorpik C. Long-term changes in posterior chamber phakic intraocular Collamer lens vaulting in myopic patients. Ophthalmology. 2010;117:1506-1511.
4. Kamiya K, Shimizu K, Aizawa D, Ishikawa H. Time course of accommodation after Implantable Collamer Lens implantation. Am J Ophthalmol. 2008;146:674-678.

Other Cited Material

A. Tanzer DJ, “U.S. FDA Clinical Trial of the Toric Implantable Collamer Lens for Moderate to High Myopic Astigmatism,” presented the annual meeting of the American Academy of Ophthalmology, Las Vegas, Nevada, USA, November 2006.
© 2013 by Lippincott Williams & Wilkins, Inc.