Effect of latrunculin-B on outflow facility in monkeys

Latrunculin-B (LAT-B), a macrolide derived from the marine sponge Latrunculia magnifica, sequesters monomeric G-actin, leading to the disassembly of actin filaments in cultured cells. In this study, we determined the effect of LAT-B on outflow facility in living monkeys. Total outflow facility was measured by 2-level constant pressure perfusion of the anterior chamber (AC) before and immediately after AC exchange infusion or 2 hr after topical application of LAT-B or vehicle. Both AC exchange infusion and topical application of LAT-B dose- and time-dependently increased outflow facility by two- to four-fold. Those findings suggest that pharmacological disorganization of the actin cytoskeleton in the trabecular meshwork by specific actin inhibitors such as LAT-B may be a useful anti-glaucoma strategy.

Loss of neurons in magnocellular and parvocellular layers of the lateral geniculate nucleus in glaucoma

OBJECTIVES

To determine whether there is loss of lateral geniculate nucleus relay neurons, which convey visual information to the visual cortex, in experimental glaucoma in monkeys.

METHOD

Four cynomolgus monkeys with experimentally induced glaucoma in the right eye (referred to as the glaucoma group) and 5 control monkeys were studied. In both groups, the same conditions of fixation, tissue processing, staining, and measurement were used. In each monkey, the left lateral geniculate nucleus target neurons in magnocellular layer 1 and parvocellular layers 4 and 6, connected to the right glaucomatous eye, were studied. Immunocytochemistry with antibody to parvalbumin was used to specifically label relay neurons connecting to the visual cortex. The number of parvalbumin-immunoreactive neurons was estimated using an unbiased 3-dimensional counting method. The t test was used to compare the experimental and control groups.

RESULTS

The mean ( SD) number of neurons in mavnocellular layer 1 was significantly decreased in the glaucoma group compared with the control group (20 692 9567 vs 37 687 8017; P = .02). The mean ( SD) number of neurons in parvocellular layers 4 and 6 was significantly decreased in the glaucoma group compared with the control group (100 141 44 906 vs 174 090 39 136; P = .03). Data are given as the mean SD.

CONCLUSION

Significant loss of lateral geniculate nucleus relay neurons terminating in the primary visual cortex occurs in the magnocellular and parvocellular layers in an experimental monkey model of glaucoma.

CLINICAL RELEVANCE

Knowledge of the fate of neurons in the central visual system may lead to a better understanding of the nature and progression of visual loss in glaucomatous optic neuropathy.

Herpes simplex virus mediated gene transfer to primate ocular tissues

We evaluated the feasibility of delivering a gene into monkey eyes using a replication-competent herpes simplex virus (HSV) type 1 ribonucleotide reductase mutant (hrR3) expressing the Escherichia coli lacZ gene. To determine the efficiency of in vitro HSV-mediated gene transfer, cultured human trabecular meshwork (HTM) and human ciliary muscle (HCM) cells were infected with hrR3 and beta-galactosidase activity was measured histochemically. Six cynomolgus monkey eyes received viral injections into the anterior chamber (2 x 10(7) pfu) and/or the vitreous (5 x 10(7) pfu), and the distribution of cells expressing lacZ was evaluated. In vitro, both cultured HTM and HCM cells displayed multiplicity-dependent beta-galactosidase activity. In vivo, intracameral and/or intravitreal injection resulted in transgene expression in TM cells and in non-pigmented ciliary epithelial cells (NPE), but not in CM cells. Transgene expression was also detected in retinal pigmented epithelial (RPE) cells and sporadic retinal ganglion cells (RGC) in eyes receiving virus intracamerally and intravitreally respectively. We observed significant inflammation in the anterior chamber, TM and CM in virus-injected eyes, along with mild vitritis and retinitis. This study demonstrates successful gene transfer using hrR3 as a vector in human ocular cells and in ocular tissues in living monkeys. Further investigation of the etiology of the inflammatory response, possible cytotoxicity, and limited duration of transgene expression is necessary in order to make this technique clinically applicable.

Reduction of collagen type I in the ciliary muscle of inflamed monkey eyes

PURPOSE

To investigate in monkey ciliary muscle the relationship between the extent of anterior segment inflammation and alterations of collagen type I as determined by quantitative imaging densitometry.

METHODS

Anterior segment inflammation was induced in one eye of five cynomolgus monkey by cannulation of the anterior chamber, by anterior chamber injection of bovine serum albumin, or by disruption of the iris and anterior lens capsule with a needle. Increases in inflammatory cells were scored in hematoxylin and eosin-stained sections. Parallel eye sections were immunostained for collagen type I and developed using diaminobenzidine. Optical density (OD) was measured along two line segments overlying the immunostained ciliary muscle using two-dimensional imaging densitometry. To assess antibody labeling of ciliary muscle structures, additional sections were double-immunostained using antibodies to collagen type I and calponin and examined by confocal microscopy.

RESULTS

In each of the inflamed eyes, hematoxylin and eosin-stained sections showed signs of chronic inflammation including lymphocytes and macrophages dispersed among ciliary muscle fibers and in the iris. Double label confocal microscopy showed collagen type I immunoreactivity in the interstitial extracellular matrix between bundles of ciliary smooth muscle fibers. Collagen type I OD scores in each of the inflamed eyes were less by 16% to 55%, compared with the contralateral control eyes. The mean of the OD scores for all inflamed eyes was 39%+/-7% less than the mean of the control eye scores (mean +/- SEM, P < 0.001). Regression analysis showed a close correlation between inflammatory cell scores in the treated eyes and the reduction of OD scores (r = 0.94, P = 0.02).

CONCLUSIONS

These results indicate that the density of collagen type I in the extracellular matrix (ECM) of monkey ciliary muscle is reduced during anterior segment inflammation and support the view that reduction of ciliary muscle ECM may contribute to increased uveoscleral outflow facility during anterior segment inflammation.

Advances in glaucoma diagnosis and therapy for the next millennium: new drugs for trabecular and uveoscleral outflow

Advances in our understanding of the physiology and molecular biology of the trabecular and uveoscleral outflow pathways of the eye will lead to the development of new approaches for glaucoma therapy. Therapies of the future will target the structures and enzymes involved in maintaining cell shape and cell-cell and cell-extracellular matrix interactions. Altering the extracellular matrix in the ciliary muscle has been important in the intraocular pressure lowering effects of prostaglandins and will be developed further as an approach to enhancing outflow through the trabecular meshwork. Gene therapy may be used to enhance or suppress the endogenous targets that are ultimately responsible for the outflow enhancement triggered by these agents.

A perspective of gene therapy in the glaucomas

Gene therapy in the anterior and posterior segment tissues may have the potential to favorably influence aqueous hydrodynamics and retinal ganglion cell biology, thereby preventing, delaying, or minimizing glaucomatous damage to the optic nerve. We demonstrated the feasibility of using a herpes viral vector (ribonucleotide reductase defective HSV-1, hrR3) to deliver the lacZ reporter gene to living cat and rat eyes. Cats received injections into the anterior chamber and rats into the vitreous cavity. In cats, lacZ expression was detectable at 1 to 2 days in the anterior outer portion of the ciliary muscle and the lining of the intertrabecular spaces of the corneoscleral and uveal meshwork. Rat eyes showed lacZ expression in the retinal pigment epithelium and photoreceptor outer segments 2 days after injection.

Latanoprost in glaucoma associated with Sturge-Weber syndrome: benefits and side-effects

PURPOSE

This study was conducted to evaluate the ocular hypotensive efficacy, safety, and side effects of latanoprost 0.005% administered as adjunctive therapy in patients with Sturge-Weber syndrome (SWS) and glaucoma.

METHODS

Commercially available latanoprost 0.005% was added as a single drop once daily to other antiglaucoma medications. Intraocular pressure (IOP) was measured at 1, 3, and 6 months of treatment. A successful response was defined as a reduction of at least 20% in IOP at the final follow-up evaluation without additional medical or surgical therapy and no adverse events related to latanoprost.

RESULTS

18 eyes of 18 patients with SWS and glaucoma were enrolled from 9 clinical centers. Mean baseline IOP was 28.4 +/- 7.1 mmHg (range, 17-42 mmHg). Using Kaplan-Meier analysis, a successful response to latanoprost was observed in 3 of 18 (16.7%) patients at the 6-month interval. Seven (38.9%) patients required surgery; three (16.7%) patients required additional medical therapy, seven (38.9%) patients had no change in therapy. One (5.6%) patient discontinued latanoprost treatment because of intolerable conjunctival hyperemia. Two successfully treated patients had significantly greater episcleral vessel engorgement after initiation of latanoprost therapy.

CONCLUSION

Patients with SWS and glaucoma respond poorly to adjunctive latanoprost therapy and often require additional medical or surgical intervention. Increased episcleral vascular engorgement might result in greater operative risks should filtration surgery become necessary in these patients.

Enthacrynic and acid effects on inner wall pores in living monkeys

PURPOSE

The influence of the inner wall of Schlemm's canal on aqueous outflow facility remains poorly understood. We examined the relationship between inner wall pore characteristics and outflow facility in living primate eyes in which facility had been pharmacologically increased by ethacrynic acid (ECA) infusion and in contralateral control eyes.

METHODS

Outflow facility (two-level constant pressure perfusion) was measured in eight pairs of living monkey eyes before and after administration of a bolus dose of either 0.125 mM ECA or vehicle. After exsanguination, eyes were fixed in situ under constant-pressure conditions (mean fixation pressure approximately 19 mm Hg). The density and diameter of inner wall pores and the number and area of platelet aggregates on the inner wall of Schlemm's canal were measured by scanning electron microscopy.

RESULTS

In ECA-treated eyes, outflow facility increased 63% (P < 0.0001), intracellular pore density decreased 46% (P = 0.0094), intracellular pore size increased 27% (P = 0.049), platelet aggregate density increased 158% (P < 0.0001), and area covered by platelets increased 210% (P = 0.012) relative to contralateral controls. Although the average density and size of intercellular pores were essentially unaffected by ECA, an increased density of large (> or = 1.90 microm) intercellular pores was seen in ECA-treated eyes. The density of intracellular pores increased with the duration of fixative perfusion. Other than a weak negative correlation between outflow facility and intracellular pore density in ECA-treated eyes (P = 0.052), facility was not correlated with inner wall pore features.

CONCLUSIONS

Our data are most consistent with a scenario in which ECA promotes formation of large intercellular pores in the inner wall of Schlemm's canal, which are then masked by platelet aggregates. Masking of intercellular pores, combined with fixation-induced alteration of inner wall pore density, greatly complicates attempts to relate facility to inner wall structure and suggests that in vivo pore density is smaller than in fixed tissue. Additionally, facility-influencing effects of ECA on the juxtacanalicular tissue cannot be excluded.

Combined effects of H-7 and cytochalasin B on outflow facility in monkeys

The serine-threonine protein kinase inhibitor H-7 and the fungal metabolite cytochalasin B (CB) disrupt the actin microfilament network by different mechanisms, and increase outflow facility similarly in live monkeys. Their combined effect has therefore determined on total outflow facility in cynomolgus monkeys by 2-level constant pressure perfusion. (1) After unilateral anterior chamber (AC) bolus injection of H-7 [10 micrometers, 100 micrometers (subthreshold for increasing facility when given alone) or 500 micrometers (just-threshold)] followed by bilateral AC bolus injection of CB [2 micrograms (strong but submaximal for increasing facility when given alone)], no significant difference between eyes was observed. (2) After bilateral AC exchange with a subthreshold dose of H-7 (10 micrometers) followed by unilateral AC bolus injection of a subthreshold dose of CB (0.02, 0.05, 0.1 or 0.5 microgram), 10 micrometers H-7 plus 0.1 or 0.5 microgram CB increased facility by approximately 40 or 80% compared to 10 micrometers H-7 alone. (3) After bilateral AC exchange with a maximal dose of H-7 (300 micrometers), followed by unilateral AC bolus injection of a subthreshold dose of CB (0.1 or 0.5 microgram), 300 micrometers H-7 plus 0.5 microgram CB increased outflow facility by 47% compared to 300 micrometers H-7 alone. (4) After unilateral AC exchange with a maximal dose of H-7 (300 micrometers) followed by bilateral AC bolus injection of a near-maximal dose of CB (2 micrograms), 300 micrometers H-7 plus 2 micrograms CB increased the facility by 67% compared to 2 micrograms CB alone. The significant effect of combined subthreshold doses of H-7 and CB on outflow facility, the potentiation of the facility-increasing effect of a maximal H-7 dose by both subthreshold and near-maximal CB doses, and the known cytoskeletal effects of both compounds, may suggest that both increase facility by disrupting actin filaments in the trabecular meshwork.

Topical prostaglandin F2alpha treatment reduces collagen types I, III, and IV in the monkey uveoscleral outflow pathway

BACKGROUND

Topical prostaglandin F2alpha isopropyl ester increases uveoscleral outflow in monkeys and humans.

OBJECTIVE

To investigate the effects of prostaglandin F2alpha isopropyl ester with topical administration on collagen types I, III, and IV within the anterior segment tissue of monkey eyes.

METHODS

Eight eyes of 4 cynomolgus monkeys were evaluated. One eye of each monkey was treated with 2 microg of prostaglandin F2alpha isopropyl ester twice daily for 5 days, and intraocular pressure reduction was confirmed. These eyes were fixed in methacarn, and paraffin sections were immunostained using antibodies to collagen types I, II, or IV. To measure staining intensity, optical density (OD) was determined using 2-dimensional imaging densitometry. Mean OD scores along line segments placed over the ciliary muscle were determined.

RESULTS

Mean+/-SD OD scores for collagen types I, III, and IV were less in the ciliary muscle of prostaglandin-treated eyes than in vehicle-treated eyes by 52%+/-7%, 45%+/-6%, and 45%+/-5%, respectively. In the sclera adjacent to the ciliary body, mean OD scores for collagen types I and III were less in prostaglandin-treated eyes, by 43%+/-32% and 45%+/-13%, respectively. The scleral stroma was minimally immunoreactive for collagen type IV. All differences were significant by the paired Student t test (P<.05).

CONCLUSIONS

This study shows reduced collagen types I, III, and IV immunoreactivity in the ciliary muscle and adjacent sclera following topical prostaglandin F2alpha isopropyl ester treatment. These reductions may contribute to the increased uveoscleral outflow observed with topical prostaglandin treatment.

CLINICAL RELEVANCE

The cellular mechanism by which certain prostaglandins lower intraocular pressure is not known. The present study provides immunohistochemical data demonstrating that intraocular pressure reduction that occurs with topical prostaglandin F2alpha is associated with a reduction of collagens within the uveoscleral outflow pathway.

The mechanism of accommodation in primates

OBJECTIVE

To study the accommodative mechanism in primates using monkeys, in light of a recently proposed novel accommodative mechanism in primates and a concomitant controversial surgical procedure for the reversal of presbyopia,

DESIGN

Experimental study.

METHODS

Accommodation was induced by stimulation of an electrode surgically implanted in the midbrain and by topical ocular application of muscarinic agonists. Pharmacologic disaccommodation was achieved by topical application of a muscarinic antagonist. Movements of the lens equator and the ciliary body were imaged during accommodation and disaccommodation using ultrasound biomicroscopy and goniovideography, and the images were analyzed to determine the direction and the extent of the movements.

RESULTS

Despite the systematic eye movements occurring with electrical stimulation and the nonsystematic eye movements occurring with pharmacologic stimulation, in all instances the ciliary body and the lens equator moved away from the sclera during accommodation.

CONCLUSIONS

Movement of the accommodative structures is consistent with the classic mechanism of accommodation described by Helmholtz, and contrary to that recently proposed by Schachar.

Latrunculin-A increases outflow facility in the monkey

PURPOSE

To determine the effect of Latrunculin (LAT)-A, a macrolide that binds to G-actin, which leads to the disassembly of actin filaments, on shape, junctions, and the cytoskeleton of cultured bovine aortic endothelial cells (BAECs) and on outflow facility in living monkeys.

METHODS

Latrunculin-A dose-time-response relationships in BAECs were determined by immunofluorescence and phase contrast light microscopy, facility by two-level constant pressure anterior chamber perfusion.

RESULTS

In BAECs, LAT-A caused dose- and incubation time- dependent destruction of actin bundles, cell separation, and cell loss. Cell-cell adhesions were more sensitive than focal contacts. Recovery was also dose- and time-dependent. In monkeys, exchange intracameral infusion and topical application of LAT-A induced dose- and time-dependent several-fold facility increases. The facility increase was completely reversed within several hours after drug removal. However, for at least 24 hours after a single topical LAT-A dose, perfusion with drug-free solution caused an accelerated increase in facility beyond that attributed to normal resistance washout.

CONCLUSIONS

Pharmacological disorganization of the actin cytoskeleton in the trabecular meshwork by specific actin inhibitors like LAT-A may be a useful antiglaucoma strategy.

Effect of staurosporine on outflow facility in monkeys

PURPOSE

To determine the effect of the serine-threonine kinase inhibitor staurosporine on outflow facility in living monkeys.

METHODS

Total outflow facility was determined by two-level constant pressure perfusion of the anterior chamber bilaterally before and after intracameral infusion of staurosporine or vehicle in opposite eyes.

RESULTS

Intracameral staurosporine dose-dependently doubled outflow facility, with 0.1 microM, 1 microM, and 10 microM being subthreshold, effective, and maximal doses, respectively. At 50 microM, intracameral staurosporine was less effective than 10 microM on facility and induced corneal toxicity.

CONCLUSIONS

The broad-spectrum protein kinase inhibitor staurosporine increases outflow facility in living monkeys, perhaps by affecting the trabecular meshwork cytoskeleton.

Latrunculin-A causes mydriasis and cycloplegia in the cynomolgus monkey

PURPOSE

To determine the effect of latrunculin (LAT)-A, which binds to G-actin and disassembles actin filaments, on the pupil, accommodation, and isolated ciliary muscle (CM) contraction in monkeys.

METHODS

Pupil diameter (vernier calipers) and refraction (coincidence refractometry) were measured every 15 minutes from 0.75 to 3.5 hours after topical LAT-A 42 microg (approximately 10 microM in the anterior chamber [AC]). Refraction was measured every 5 minutes from 0.5 to 1.5 hours after intracameral injection of 10 microl of 50 microM LAT-A (approximately 5 microM in AC), with intramuscular infusion of 1.5 mg/kg pilocarpine HCl (PILO) during the first 15 minutes of measurements. Pupil diameter was measured at 1 and 2 hours, and refraction was measured every 5 minutes from 1 to 2 hours, after intravitreal injection of 20 microl of 1.25 mM LAT-A (approximately 10 microM in vitreous), with intramuscular infusion of 1.5 mg/kg PILO during the first 15 minutes of measurements (all after topical 2.5% phenylephrine), and contractile response of isolated CM strips, obtained <1 hour postmortem and mounted in a perfusion apparatus, to 10 microM PILO +/- LAT-A was measured at various concentrations.

RESULTS

Topical LAT-A of 42 microg dilated the pupil without affecting refraction. Intracameral LAT-A of 5 microM inhibited miotic and accommodative responses to intramuscular PILO. Intravitreal LAT-A of 10 microM had no effect on accommodative or miotic responses to intramuscular PILO. LAT-A dose-dependently relaxed the PILO-contracted CM by up to 50% at 3 microM in both the longitudinal and circular vectors.

CONCLUSIONS

In monkeys, LAT-A causes mydriasis and cycloplegia, perhaps related to its known ability to disrupt the actin microfilament network and consequently to affect cell contractility and adhesion. Effects of LAT-A on the iris and CM may have significant physiological and clinical implications.

Immunohistochemical localization of dopamine-beta-hydroxylase in human and monkey eyes

PURPOSE

To investigate the pattern of dopamine-beta-hydroxylase (DBH)-containing fibers in human and monkey eyes.

METHODS

DBH-containing fibers were detected by immunohistochemistry. The primary antibody used recognized DBH, the key enzyme in the conversion of dopamine to noradrenaline.

RESULTS

In the anterior segment, DBH immunoreaction product was found in the peripheral corneal endothelium layer, in both the dilator and sphincter muscles of the iris, as well as in the anterior border layer of the iris. The ciliary muscle and the stroma of the ciliary processes were also zones of concentration. In the posterior segment, staining was seen around blood vessels in the choroid, in the vascular walls of the short posterior ciliary arteries and in the ciliary nerves. The retina was also immunopositive, with specific labeling in cones and rods of photoreceptors, inner and outer plexiform layers and ganglion cell layer. There was no significant difference in the distribution of DBH-related immunoreactivity in human and monkey eyes.

CONCLUSIONS

The localization of DBH-related immunoreactivity is generally consistent with the known physiological roles of noradrenaline. However, an apparently high concentration of the enzyme in the anterior border layer of the iris and in retinal photoreceptors raises questions about the possible role of DBH-containing fibers in these structures.

H-7 increases trabecular facility and facility after ciliary muscle disinsertion in monkeys

PURPOSE

To determine the effects of the serine-threonine kinase inhibitor H-7 on total outflow facility in iridectomized + ciliary muscle (CM)- disinserted, and on trabecular facility in normal, monkey eyes.

METHODS

Total outflow facility was determined by two-level constant pressure perfusion of the anterior chamber. Trabecular outflow facility was determined from accumulation in blood of intracamerally infused radioiodinated albumin at two intraocular pressure levels.

RESULTS

Three-hundred micromoles of intracameral H-7 doubled facility in iridectomized + CM- disinserted monkey eyes and contralateral iridectomized-only eyes. Four 5-microl drops of 400 mM H-7 applied topically followed 2 hours later by anterior chamber exchange for 10 minutes and intracameral infusion for 90 minutes with 100 microM H-7 increased trabecular and total outflow facility by 135%+/-29% and 105%+/-35% (n 5, P < 0.01, P < 0.05), respectively, compared with contralateral vehicle-treated eyes.

CONCLUSIONS

H-7 increases trabecular outflow facility in monkeys by a mechanism independent of the CM, presumably acting directly on the trabecular meshwork.

Endothelin-1 effects on aqueous humor dynamics in monkeys

PURPOSE

To report data showing no effect of endothelin-1 on aqueous humor formation and total outflow facility in the cynomolgus monkey, in contrast to the enhancement of outflow facility in monkeys and the suppression of aqueous humor flow in rabbits previously reported by others.

METHODS

Living monkeys received, unilaterally: (i) intracameral endothelin-1 (10 microl bolus, or 2ml or 4ml exchange; final intracameral concentration 1 or 10 nM) with total outflow facility measured for up to 1 hr post-treatment by two-level constant pressure perfusion, and (ii) intravitreal endothelin-1 (20 microl, final intravitreal concentration 0.1 or 1 microM) with aqueous humor flow measured by scanning fluorophotometry for 5 hr starting 12 hr post-treatment. Contralateral eyes received vehicle.

RESULTS

Endothelin-1 had no effect on total outflow facility or aqueous humor flow with any of the methods described.

CONCLUSION

Endothelin-1 seems have a variable effect on aqueous humor dynamics within and between species.

Accommodation dynamics in aging rhesus monkeys

Accommodation, the mechanism by which the eye focuses on near objects, is lost with increasing age in humans and monkeys. This pathophysiology, called presbyopia, is poorly understood. We studied aging-related changes in the dynamics of accommodation in rhesus monkeys aged 4-24 yr after total iridectomy and midbrain implantation of an electrode to permit visualization and stimulation, respectively, of the eye's accommodative apparatus. Real-time video techniques were used to capture and quantify images of the ciliary body and lens. During accommodation in youth, ciliary body movement was biphasic, lens movement was monophasic, and both slowed as the structures approached their new steady-state positions. Disaccommodation occurred more rapidly for both ciliary body and lens, but with longer latent period, and slowed near the end point. With increasing age, the amplitude of lens and ciliary body movement during accommodation declined, as did their velocities. The latent period of lens and ciliary body movements increased, and ciliary body movement became monophasic. The latent period of lens and ciliary body movement during disaccommodation was not significantly correlated with age, but their velocity declined significantly. The age-dependent decline in amplitude and velocity of ciliary body movements during accommodation suggests that ciliary body dysfunction plays a role in presbyopia. The age changes in lens movement could be a consequence of increasing inelasticity or hardening of the lens, or of age changes in ciliary body motility.

The rarity of clinically significant rise in intraocular pressure after laser peripheral iridotomy with apraclonidine

OBJECTIVE

To determine the incidence of intraocular pressure (IOP) rise of varying degrees after laser peripheral iridotomy (LPI) in patients with and without glaucoma treated perioperatively with pilocarpine and apraclonidine.

DESIGN

A retrospective chart review.

PARTICIPANTS

A total of 289 eyes in 179 patients with narrow occludable angles (NOA) (N = 148), open-angle glaucoma or ocular hypertension (OAG) (N = 115), or chronic-angle closure glaucoma (CACG) (N = 26) were reviewed.

MAIN OUTCOME MEASURES

The difference between preoperative and postoperative IOP, absolute postoperative IOP, and the need for acute IOP-lowering treatment was noted.

RESULTS

Only 1.1% (95% confidence interval [CI], 0.03%-5.8%; 1 of 94) of patients and 0.7% (95% CI, 0.02%-3.7%; 1 of 148) of eyes with NOA experienced a rise of more than 10 mmHg 1 to 2 hours after LPI. The incidence of postoperative IOP greater than 25 mmHg and acute postoperative IOP-lowering management was 0% (95% CI, 0%-3.8%). Intraocular pressure in 1 of 115 eyes (0.9%, 95% CI, 0.02%-4.7%) with OAG rose more than 10 mmHg, requiring acute treatment. None of the 26 CACG eyes experienced a rise of more than 10 mmHg (95% CI, 0%-13.2%).

CONCLUSION

The IOP rise that requires further intervention after LPI with the perioperative use of pilocarpine and apraclonidine is very uncommon. In patients with NOA, routine postiridotomy IOP monitoring may not be required.

Effect of ticrynafen on aqueous humor dynamics in monkeys

OBJECTIVE

To determine the effect of ticrynafen, a nonsulfhydryl-reactive compound similar to ethacrynic acid, on outflow facility in normotensive monkey eyes and on intraocular pressure (IOP) in monkey eyes with laser-induced glaucoma.

METHODS

In normotensive eyes, facility (perfusion) was measured shortly before and after bolus or exchange intracameral infusion of ticrynafen or vehicle in opposite eyes, and 3.5 to 4.5 hours after 5 days of twice-daily 2% ticrynafen or vehicle ointment. In glaucomatous eyes, baseline and vehicle diurnal IOP curves were established, 2% ticrynafen ointment was given twice daily for 5 days, and IOP was measured immediately before and 0.5 to 6 hours after each morning treatment.

RESULTS

In normotensive eyes, exchange 2-mL influsion of 0.2-, 1-, or 4-mmol/L ticrynafen increased facility by 33% +/- 6% (mean +/- SEM), 73% +/- 18%, and 60% +/- 11%, respectively. Day 5 posttreatment facility was higher in the ticrynafen group than in controls by 28% +/- 9%. In glaucomatous eyes, maximum IOP decline, from approximately 35 mm Hg, was 7.5 +/- 2.0 mm Hg on day 4 and 9.8 +/- 2.4 mm Hg on day 5 of twice-daily ticrynafen treatment.

CONCLUSION

The facility-increasing, IOP-lowering action of ticrynafen, ethacrynic acid, and derivatives may not depend entirely on sulfhydryl reactivity.

CLINICAL RELEVANCE

Whether such drugs as ethacrynic acid and ticrynafen prove valuable for glaucoma therapy, at the least they are useful probes to study aqueous outflow mechanisms.