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Early postop cloudiness of IOLs attributed to storage conditions
The authors recommend cautions in environmental conditions for IOL storage.
 Three-piece silicone IOL explanted in Brazil. The lens had been bisected for explantation. The photographs were taken at different times after removal of the lens from solution. The opacity disappeared after the lens dried. Images: Werner L  Sagittal view of the optic of a three-piece silicone IOL explanted in Brazil. The optic opacity had a yellow color under light microscopy. |
Recently performed analyses of explanted silicone IOLs led to the conclusion that environmental factors in storage areas may be responsible for changes in IOLs, leading to their opacification shortly after implantation. This work, which I presented at the American Society of Cataract and Refractive Surgery meeting in San Diego, was done in collaboration with Fabio Dornelles, MD, Christiana Hilgert, MD, Fernando Botelho, MD, Paulo Conte, MD, from Brazil, and with Nick Mamalis, MD, and Randall J. Olson, MD, from the John A. Moran Eye Center, University of Utah.
Four three-piece silicone lenses were explanted by surgeons in four locations in Brazil. Uneventful phacoemulsification with implantation of these IOLs was performed from April 2003 to June 2003. Significant opacification of the lenses’ optical component was observed as early as 7 hours after the surgery. The patient’s visual acuity or contrast sensitivity was significantly affected in each case. Once lens opacification was noted, no further changes in the appearance of the lenses were observed. The lenses were then explanted and exchanged 2 to 8 weeks after the initial implantation procedure. According to the surgeons, it was not difficult to dial the recently implanted lenses into the anterior chamber. Each lens was then totally or partially bisected and removed through a small incision. Any fibrosis of the capsulorrhexis edge (not uncommonly seen relatively early in the postoperative period with silicone lenses) was excised, and the capsular bag was re-expanded with viscoelastics. In two of the cases, a lens of the same design was used for the exchange. The postoperative course in all cases was uneventful. After each lens exchange, the patient’s visual function improved.
Explanted IOLs examined
The explanted lenses were sent to the John A. Moran Eye Center in balanced salt solution. They were removed from the solution for photo documentation and analyses. Surprisingly, the opacification progressively decreased and then completely disappeared while the lenses were drying out (Figure 1). The same phenomenon was observed under light microscopy, where the opacity was seen with a yellowish color (Figure 2). Contrary to the late postoperative opacification observed with some hydrophilic acrylic designs caused by calcium/phosphate deposits (Figure 3), in the case of these four silicone lenses, no significant deposition was found on the surfaces or inside the lenses. These results indicate that influx of aqueous fluid within these lenses was responsible for early postoperative cloudiness.
The lenses were immersed in isopropyl alcohol for 24 hours for analyses of absorbed volatile and semivolatile chemicals. Suspect exogenous molecules were identified. These included terpenes and ketones, which are typically found in cleaning agents and fumigants. These molecules were found to cause changes in the surfaces of silicone lenses in vitro, allowing influx of water and thus cloudiness. Although the four lenses analyzed were from different manufacturer batches, they were stored at some point at the same area in Brazil.
Volatile solutions
It has been postulated that, during the cleaning and disinfection of storage rooms, aerosolized or volatile solutions may be inadvertently introducing chemicals through the package and onto the lenses. This may cause surface changes, for example rendering a normally hydrophobic silicone lens relatively hydrophilic, promoting opacification in the aqueous environment. Medical staff cannot forget that most IOLs are enclosed in vapor-permeable packages to allow sterilization by ethylene oxide gas. At the John A. Moran Eye Center in Salt Lake City, no sprays or aerosolized solutions are used in the room where the IOLs are stored. The room is mopped and wet-dusted with cloths containing a germicidal solution daily. Any volatile solutions present in this area, such as sterilizing solutions for example, are strictly kept in closed containers at all times. The entire operating area, including storage rooms, are kept at a temperature ranging from 68° to 72° F, and humidity between 35% and 45%. The area is also constantly ventilated, with 11 turnovers of air per hour.
We therefore recommend that, when a medical facility needs to be sprayed with volatile chemicals, it should not contain IOL packages at that time. Also, all lenses should be stored in a relatively dry environment and at room temperature. This complication may eventually represent a potential problem for any kind of lens enclosed in semipermeable packages.
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For Your Information:References:
- Liliana Werner, MD, PhD, can be reached at John A. Moran Eye Center, University of Utah, 50 N. Medical Dr., Salt Lake City, UT 84132; 801-581-8136; fax: 801-581-3357; e-mail: liliana.werner@hsc.utah.edu.
- Hilgert CR, Hilgert A, et al. Early opacification of silicone intraocular lenses. J Cataract Refract Surg. 2004 (in press).
- Werner L, et al. Exogenous contamination leading to early cloudiness of silicone intraocular lenses: Laboratory analyses of four explants. J Cataract Refract Surg. 2004 (in preparation).
- Werner L, Apple DJ, et al. Postoperative desposition of calcium on the surfaces of a hydrogel intraocular lens. Ophthalmology. 2000;107:2179-2185.
- Werner L, Apple DJ, et al. Dense opacification of the optical component of a hydrophilic intraocular lens: A clinicopathological analysis of nine explanted lenses. J Cataract Refract Surg. 2001;27:1485-1492.