References And Further Reading

Barabino S, Rolando M, Camicione P, et al. Effects of a 0.9% sodium chloride­ . ophthalmic solution on the ocular surface of symptomatic contact lens wearers. Can J Ophthalmol 40: 45–50, 2005.

Kushner FH. Sodium chloride eye drops as a cause of epistaxis. Arch Ophthalmol 105: 1643, 1987.

Shapiro A, et al. The effect of salt loading diet on the intraocular pressure. Acta Ophthalmol 60: 35, 1982.

Shaw EL. Allergies induced by contact lens solution. Contact Lens 6: 273, 1980.

Spizziri LJ. Stromal corneal changes due to preserved saline solution used in soft contact lens wear: report of a case. Ann Ophthalmol 13: 1277, 1981.

Class: Viscoelastics

Generic name: Sodium hyaluronate.

Proprietary names: AMO Vitrax, Amvisc, Coease, Euflexxa, Healon, Hyalgan, Orthovisc, Provisc, Restylane, Shellgel, Supartz, Synvisc, Viscoat.

to prevent myopia, shallow anterior chamber and a distended capsular­ bag. Berger et al (1999) described a case of suspected ciliary­ block glaucoma caused by the viscoelastic agent being misdirected into the vitreous through an unsuspected small zonular dialysis. This required a vitrectomy and peripheral iridectomy to resolve. Since postoperative uveitis is common, it is difficult to determine a true incidence of inflammation attributed directly to these agents. However, this was more of a problem initially than it is currently. Studies by Storr-Paulsen and Larsen (1991) show little difference in the severity of iritis among the various viscoelastics. In general, these products seldom cause a significant inflammatory response. Jensen et al (1994) described a series of patients with visually significant deposition of a high molecular weight sodium hyaluronate (Healon GV®). These deposits may remain up to 6 months and decrease vision to 20/40 or worse. Isolated cases have been reported of corneal opacities occurring after inadvertent corneal injection of viscoelastics but they seem to absorb and resolve in a matter of months. There is little evidence that the viscoelastics bind with drugs to inhibit their action in the eye.

Primary use

These are primarily used as viscoelastic materials in ophthalmic surgery.

Ocular side effects

Local ophthalmic use of exposure – intraocular

Certain

1. Elevated intraocular pressure

2. Opacities (corneal injection)

3. Crystalline deposition on intraocular lenses (high molecular weight)

4. Myopia

5. Ciliary block glaucoma

Possible

1. Uveitis – transient

Clinical significance

Improvements have been made in the manufacture of visco­ elastics since the 1970s, and many of the initial adverse events, such as uveitis or precipitation of calcium salts due to excessive phosphate in the buffer, have now been eliminated. Floren (1998) showed that since autoclaving degrades high molecular weight hyaluronic acid molecules, it may still be a problem to keep these products free of endotoxins. The sodium salt of hyaluronic acid is sodium hyaluronate, which is one of the more commonly used viscoelastics. All of the viscoelastics can cause transitory elevations in pressure, usually peaking between 6 and 12 hours and returning to normal within 24 hours. This pressure elevation seems to be more acute and lasting in patients with glaucoma. There is some evidence that lower molecular weight viscoelastics do not produce as great a pressure elevation as those with higher molecular weights. Tanaka et al (1997) have shown that viscosity is important as well. It is recommended that washout times of at least 10 seconds are necessary to help prevent intraocular pressure elevations. Shammas (1995), Holtz (1992) and Reck et al (1998) describe entrapment of a viscoelastic in the capsular bag. This material is very slow to absorb and may require a surgical procedure, as it did in these three cases,

References And Further Reading

Alpar JJ. Comparison of healon and amvisc. Ann Ophthalmol 17: 647–651, 1985.

Berger RR, Kenyeres AM, Powell DA. Suspected ciliary block associated with Viscoat use. J Cataract Refract Surg 25(4): 594–596, 1999.

Daily L. Caution on sodium hyaluronate (Healon) syringe. Am J Ophthalmol 94(4): 59, 1982.

Floren I. Viscoelastic purity. J Cataract Refract Surg 24(2): 145–146, 1998. Glasser DB, Matsuda M, Edelhauser HF. A comparison of the efficacy and

toxicity of and intraocular pressure response to viscous solutions in the anterior chamber. Arch Ophthalmol 104: 1819–1824, 1986.

Goa KL, Benfield P. Hyaluronic acid: A review of its pharmacology and use as a surgical aid in ophthalmology, and its therapeutic potential in joint disease and wound healing. Drugs 47(3): 536–566, 1994.

Holtz SJ. Postoperative capsular bag distension. J Cataract Refract Surg 18: 310–317, 1992.

Hoover DL, Giangiacomo J, Benson RL. Descemet’s membrane detachment by sodium hyaluronate. Arch Ophthalmol 103: 805–808, 1985.

Jensen MK, et al. Crystallization on intraocular lens surfaces associated with the use of Healon GV. Arch Ophthalmol 112: 1037–1042, 1994.

MacRae SM, et al. The effects of sodium hyaluronate, chondroitin sulfate, and methylcellulose on the corneal endothelium and intraocular pressure. Am J Ophthalmol 95: 332–341, 1983.

McDermott ML, Edelhauser HF. Drug binding of ophthalmic viscoelastic agents. Arch Ophthalmol 107: 261–263, 1989.

Pape LG, Balazs EA. The use of sodium hyaluronate (Healon®) in human anterior segment surgery. Ophthalmology 87(7): 699–705, 1980.

Passo MS, Ernest JT, Goldstick TK. Hyaluronate increases intraocular pressure when used in cataract extraction. Br J Ophthalmol 69(8): 572–575, 1985.

Reck AC, Pathmanathan T, Butler RE. Post-operative myopic shift due to trapped intracapsular Healon (letter). Eye 12(Pt 5): 900–901, 1998.

Shammas HJ. Relaxing the fibrosis capsulorhexis rim to correct induced hyperopia after phacoemulsification. J Cataract Refract Surg 21: 228–229, 1995.

Sholohov G, Levartovsky S. Retained ophthalmic viscosurgical device material in the capsular bag 6 months after phacoemulsification. J Cataract Refract Surg 31: 627–629, 2005.

Storr-Paulsen A. Analysis of the short-term effect of two viscoelastic agents on the intraocular pressure after extracapsular cataract extraction. Acta Ophthalmol 71: 173–176, 1993.

Storr-Paulsen A, Larsen M. Long-term results of extracapsular cataract extraction with posterior chamber lens implantation. Acta Ophthalmol 69: 766–769, 1991.

Tanaka T, Inoue H, Kudo S, et al. Relationship between postoperative intraocular pressure elevation and residual sodium hyaluronate following phacoemulsification and aspiration. J Cataract Refract Surg 23(2): 284–288, 1997.