Clinical Evaluation of the Use of Sealed Capsule Irrigation With Sodium Chloride During Pediatric Cataract Surgery and IOL Implantation

Dramatic advances have occurred in the treatment of childhood cataracts in the last 10 years. Intraocular lens implantation (IOL) has been universally accepted as standard of care in children beyond 2 years of age. Despite advances in cataract surgery in children, PCO remained a significant complication following pediatric cataract surgery. In addition to being visually disturbing, it also induces amblyopia in children and if not treated at earliest, irreversible visual changes may occur. The younger the child, more acute is the problem: PCO occurs faster and effect of amblyopia is more pronounced. PCO generally requires second surgical intervention, as closure of the opening made by YAG capsulotomy is very common after pediatric cataract surgery. Many times, children are not cooperative to sit down for YAG capsulotomy, and that may also be an additional indication for second surgery for PCO.

Removal of residual epithelial cells is one of the key factors to avoid the complication of PCO. Several chemicals have been suggested in experimental settings to remove or kill these residual lens epithelial cells. However, they are toxic to other ocular structures. Researchers are searching for a device which can help to selectively kill these lens epithelial cells. In the long term, this may help to avoid PCO.

Perfect Capsule: Perfect CapsuleTM (Milvella ltd) is a sterile single use ophthalmic instrument used to perform sealed irrigation of the capsular bag during cataract surgery in order to facilitate irrigation of the capsule without the irrigation fluid contacting other ocular structures. The device has the FDA approval via 510(k) in the USA, and is CE marked in Europe. No specific age limit has been listed for FDA approval. The device (see fig) consists of a 7 mm diameter head, a 3 mm wide body and a 4 mm wide foot that remains external to the eye. The head of the device comprises a circumferential vacuum channel connected to a vacuum syringe via a vacuum tube. The central portion of the head forms a plug with an irrigation/aspiration (I/A) channel (the body) which extend through the cornea allowing fluids to be injected into the under surface of the plug and thus into the capsule. The device has an internal diameter of 5 mm, is molded in medical grade silicone, packaged and gamma sterilized. It can be easily rolled or folded to pass through the standard corneal incision into the eye and positioned on the anterior surface of the capsule using standard ophthalmic instrument.

Concentrated Sodium Chloride: Concentrated Sodium Chloride injection, USP 23.4% (American Regent Laboratories, Inc., Shirley, NY) is sterile, preservative free, nonpyrogenic solution of Sodium Chloride in water for injection. Deionised water has been shown to lyse lens epithelial cells through osmotic flow. Concentrated Sodium Chloride is not currently indicated for intraocular use and is also expected to affect the corneal endothelium. Use of Perfect Capsule will help to avoid the contact of Concentrated sodium Chloride to the endothelial cells.

For the purpose of this study, Concentrated Sodium Chloride for injection will be colored with minimal fluorescein so that the flow and location of it can be visualized throughout the procedure. Viscoelastic within the anterior chamber will provide additional protection for the corneal endothelium.

SCI with Perfect Capsule and Concentrated Sodium Chloride: Perfect CapsuleTM allows for the empty capsular bag to be irrigated with Concentrated Sodium Chloride. A previous study in rabbits has shown that toxic solutions can be safely used for SCI. It has also been shown that the irrigation solution is contained within the capsular bag when SCI is performed in humans. Dr. Auffarth has presented a summary of the two year Australian study results and one year European multi-center clinical trial results performing SCI with distilled water in humans (At American Society of Cataract and Refractive Surgery meeting, 2005). In 44 patients studied, the system could be used without complication and the endothelial cell count and corneal pachymetry was not different from the control eyes. Visual acuity development over a 6-12 months period was similar in both groups. Retro-illumination photographs showed a higher incidence of fibrosis and anterior capsule whitening in the control group compared to the SCI group. With the currently available IOLs, PCO is not a significant complication in adult eyes at 1-2 year postoperative period. Long-term results will be needed to detect the difference (if any) in terms of PCO in adult eyes. In contrast, PCO is a significant problem in pediatric eyes. It occurs at a much faster rate and during early postoperative period in children's eyes as compared to adult's eyes. Younger the child at the time of cataract surgery, more acute is the problem. Thus, it is possible to see the difference in terms of PCO (if any) with the use of Perfect Capsule in children's eyes during early postoperative period, as 1 year postoperatively in this study. We are not aware of any published results or results presented at the meeting showing use of SCI or distilled water in pediatric eyes.