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[Postoperative intraocular pressure in the first days after intraocular administration of hyaluronic acid solution
Background:
Viscoelastic substances are used in anterior segment surgery to reduce tissue trauma and endothelial cell loss and to serve as space maintainer. Healon GV (approximately greater viscosity), a hyaluronic acid product with a ten times higher viscosity than Healon, is utilized in complicated procedures (vitreous pressure, flat anterior chamber, congenital cataracts, etc.) and often in phacoemulsification. Intraocular pressure (IOP) rise following incomplete removal is a known problem.
Materials And Methods:
A prospective randomized study was performed to evaluate the IOP following cataract surgery with Healon or Healon GV and different removal times (RT). Forty patients (forty eyes) having uncomplicated phacoemulsification with foldable silicone posterior chamber lens implantation and identical viscoelastic removal technique were assigned to four groups: Healon with 20 or 40 seconds (sec.) RT, Healon GV with 20 or 40 sec. RT. All surgeries were performed by the same surgeon using the same technique especially for the removal of the viscoelastic. All patients had an identical pre- and postoperative medication. Intraocular pressures were obtained using Goldman's applanation tonometry preoperatively, six, 24, 36, and 48 hours postoperatively.
Results:
The IOP follow-up showed no significant difference between the two viscoelastic substances and the two different removal times of 20 and 40 sec. (t-test). In four patients (two of the Healon-groups, two of the Healon GV-groups) the IOP required treatment. On the second postoperative day, the same four patients showed IOP lower than 22 mm Hg. The highest mean-IOP (mm Hg) in both Healon-groups was obtained at 24 hours postoperatively: 18.5 +/- 3.9 SD (Healon); 17.3 +/- 5.9 SD (Healon GV).
Conclusion:
The incidence of postoperative rise in IOP using high viscosity hyaluronic acid (Healon GV) can be minimized by the applied removal technique. Both viscoelastics-despite of higher molecular weight and viscosity-can be removed equally from the anterior chamber following phacoemulsification and posterior chamber lens implantation utilizing IOP as a parameter in vivo.