Prospective comparison of the effects of Occucoat, Viscoat, and Healon on intraocular pressure and endothelial cell loss.

We compared the effect of Occucoat (2% hydroxypropylmethyl-cellulose), Viscoat (sodium hyaluronate-chondroitin sulfate), and Healon (sodium hyaluronate) on postoperative intraocular pressure (IOP) and endothelial cell damage. One hundred fourteen patients having planned extracapsular cataract extraction with posterior chamber lens implantation using a viscomaterial were prospectively randomized into one of five groups. Group I received Occucoat which was removed from the anterior chamber at the conclusion of surgery. Group II received Occucoat which was not removed (retained). Group III received Viscoat which was removed, Group IV received Viscoat which was retained, and Group V received Healon which was removed. No prophylactic ocular hypotensive medications were given. Intraocular pressure was measured at four hours, 24 hours, one week, one month, three months, and one year postoperatively. Compared to preoperative IOP, all groups had a significant IOP increase at four hours. All but the Viscoat removed group (Group III) showed a statistically significant increase at 24 hours postoperatively (P less than .05). No group had a significant increase at one week or later. Specular microscopy showed no significant difference in cell loss between any of the groups at three months or within each group when compared to preoperative cell counts (P greater than .1).

Terbutaline stimulates aqueous humor flow in humans during sleep.

A randomized, double-masked study of the effect of terbutaline sulfate, a selective beta 2-agonist, on the rate of aqueous humor formation was performed in awake and sleeping normal human subjects. The rate of aqueous formation was measured by fluorophotometry. Both the drug- and placebo-treated eyes showed a statistically significant nocturnal reduction of the flow rate (36% suppression in the terbutaline-treated eyes and 43% suppression in the placebo-treated eyes). Terbutaline had no effect on daytime aqueous flow rates, but stimulated flow by 15% during sleep. The drug had no significant effect on intraocular pressure. This study confirms past observations that beta-agonists exert their maximal effects during sleep, when endogenous adrenergic stimulation is at a minimum.

6-amino-2-benzothiazole-sulfonamide. The effect of a topical carbonic anhydrase inhibitor on aqueous humor formation in the normal human eye.

The carbonic anhydrase inhibitor, 6-amino-2-benzothiazolesulfonamide, formulated as a 3% suspension in a gel vehicle was instilled in one eye of 21 human subjects in a single dose study to determine its effect on aqueous dynamics. A small but statistically significant effect on aqueous humor flow was observed 2 to 7 hours after application. By 8 hours, the effect had disappeared, and intraocular pressure (IOP) measured 8 hours after application of a single dose was unchanged in these normal volunteers. The drug and its vehicle caused local side effects including irritation, hyperemia, and blurred vision. The authors wondered if multiple doses would produce a greater effect. Four subjects received up to four doses of the drug over 2 days and were restudied. Marked bulbar injection and follicular conjunctivitis, attributable to either the drug or the vehicle, developed in two of the subjects, both contact lens wearers. A milder form of bulbar injection and follicular conjunctivitis developed in a third subject, who received three doses of the drug and was not a contact lens wearer. These side effects precluded additional multiple-dose testing of this formulation of the drug, and no conclusions about the effect of the drug on aqueous flow can be drawn from this portion of the study.

Prostaglandin F2 alpha-1-isopropylester lowers intraocular pressure without decreasing aqueous humor flow.

Using fluorophotometry, we performed a randomized, dose-response study of the effects of a prostaglandin derivative on aqueous humor flow. Prostaglandin F2 alpha 1-isopropylester, 0.224 micrograms, 0.448 micrograms, and 1.120 micrograms, in saline with polysorbate 80 was instilled into one eye of 20 subjects in three separate dose studies. Polysorbate 80 in saline was instilled in the fellow eye as a control. The drug had no measurable effect on aqueous humor flow or corneal endothelial permeability. Intraocular pressure measured eight hours after administration of the highest dose, 1.120 micrograms, was 20% lower in the treated eye as compared to the fellow eye (P less than .001).

Topical forskolin (colforsin) and aqueous flow in humans.

A 1% forskolin (nonproprietary name, colforsin) suspension was instilled in one eye each of 15 normal human subjects in a single-dose experiment under the following three conditions: during the day, during the night while asleep, and following pretreatment with timolol maleate. The rate of flow was 2.6 +/- 0.13 microL/min (mean +/- SE) in the afternoon in both the treated and the untreated eyes. During sleep at night the flow was lower than in the afternoon in both the placebo-treated eye, 1.5 +/- 0.09 microL/min, and the forskolin-treated eye, 1.3 +/- 0.09 microL/min. Timolol pretreatment reduced the flow to 1.6 +/- 0.08 microL/min in the placebo-treated eye and 1.6 +/- 0.10 microL/min in the forskolin-treated eye. No statistically significant effects of forskolin on flow were observed under any of the conditions. Forskolin caused transient hyperemia in all subjects. The experiment confirmed previous reports of differences in the rate of aqueous flow at different times of day and the effect of the beta-adrenergic blocker timolol on the rate of aqueous humor flow.