Reversal of topical antiglaucoma medication effects on the conjunctiva

OBJECTIVE

To determine whether the adverse effects of antiglaucoma medications could be reversed before filtration surgery, potentially reducing the risk of subsequent failure.

METHODS

One month before surgery, 30 patients who were receiving multiple antiglaucoma medications underwent an inferior bulbar conjunctival biopsy, ceased using sympathomimetic drops, and began treatment with topical corticosteroid, (1% fluorometholone four times daily). At the time of surgery two conjunctival biopsy specimens were obtained, one from the operation site (superior bulbar region), and one from the inferior bulbar region. The biopsy specimens were quantitatively analyzed by light microscopy. In addition, the outcome of first trabeculectomy for 16 of these patients was compared with that of 16 matched patients who had not undergone an altered preoperative regimen of topical therapy.

RESULTS

During a 1-month period a notable decrease occurred in the number of fibroblasts and inflammatory cells throughout the conjunctiva. Inferior bulbar conjunctiva was found to be representative of superior bulbar conjunctiva with respect to these changes. Furthermore, evidence comparing the matched patients suggested that the altered preoperative regimen may have improved the success rate of trabeculectomy.

CONCLUSIONS

The preoperative regimen used reversed the adverse conjunctival effect of topical medication. The regimen may be of clinical benefit in improving the success rate of trabeculectomy.

Laser suture lysis after mitomycin C trabeculectomy

PURPOSE

To evaluate the timing, efficacy, and complications of laser suture lysis (LSL) after mitomycin C trabeculectomy in patients with glaucoma at high risk for failure of filtering surgery.

METHODS

The authors retrospectively reviewed the charts of 62 consecutive patients who underwent a total of 66 sessions of LSL after trabeculectomy with mitomycin C.

RESULTS

The interval from surgery to LSL ranged from 2 to 65 days (mean +/- standard deviation, 17.9 +/- 14.9 days). The average intraocular pressure (IOP) reduction after LSL was 11.9 +/- 8.9 mmHg (range, 3-40 mmHg). A longer interval to LSL was correlated with a lesser degree of pressure reduction (P=0.0004, Wilcoxon rank-sum test). After LSL, hypotony developed in 13 (21%) patients (IOP < 6 mmHg on 2 consecutive measurements at least 24 hours apart). This resolved spontaneously after 7 to 304 days (104.1 +/- 109.1 days) in 12 (92%) of the 13 patients. Life-table success rates (success defined as 6 mmHg </= final IOP </= 21 mmHg) for the hypotony and no hypotony groups were 100% and 86% (at 6 months) and 96% and 86% (at 12 months), respectively. The final visual acuity worsened in a significantly greater percentage of patients in the hypotony group (46%) compared with the no-hypotony group (18%) (P = 0.06), Fisher's exact test).

CONCLUSIONS

Laser suture lysis is safe and effective in augmenting aqueous filtration after mitomycin C trabeculectomy. A longer time interval between surgery and LSL may result in both a lesser degree of IOP reduction and a lower incidence of subsequent hypotony.

Holmium YAG laser sclerostomy ab externo for refractory glaucoma

Ab externo thermal sclerostomy was performed with the holmium YAG (thulium, holmium, chromium-doped YAG crystal) laser in 21 eyes of 20 patients with refractory glaucoma. We used either the 5-fluorouracil (5-FU) or mitomycin C (MMC) antimetabolites in all cases. The rate of intraocular pressure (IOP) control defined as IOP < 21 mmHg regardless of whether antiglaucoma medication was applied postoperatively) was estimated by the life-table methods of Kaplan-Meier. The postoperative IOP control rate was 47.1% in the MMC-treated group at 57 months, and 14.3% in the 5-FU-treated group at 52 months. There were statistically significant differences in success rates between the MMC- and 5-FU-treated groups. We observed no clinically significant complications except excess filtration associated with a shallow anterior chamber in one case. This procedure is thought to have several advantages over more conventional filtration surgery; the operation time is shorter, and there is no need for intraocular manipulation, which means conjunctival trauma is minimal. However, the IOP control rate was substantially lower than that achieved via conventional trabeculectomy. Our results suggest that the selection of patients and the use of MMC is an important factor in maintaining successful filtration.

Mechanisms of failure in glaucoma filtering surgery: a consequence of antiglaucomatous drugs?

An increasing number of studies, both experimental and epidemiologic, have provided evidence that filtering glaucoma surgery may be less effective than initially described. Of a number of risk factors for failure, duration and number of antiglaucoma drugs prior to surgery seem to play a critical role and highly accumulated antiglaucoma topical treatments significantly reduce success rates. Histopathological studies have confirmed that topically applied drugs may exert toxic effects to the corneoconjunctival surface, and induce chronic infraclinical inflammation, as shown by the presence of immune and inflammatory infiltrates in multitreated eyes. The origin of topical inflammation has not yet been clearly determined, but a common component of ophthalmic drugs, the benzalkonium chloride used as preservative in almost all antiglaucoma preparations, has shown strong evidence of toxicity. A number of questions remain to be investigated, but suppression of preservatives from chronically applied drugs should be a critical issue in the near future.

The effects of antiglaucomatous agents on conjunctiva used for various durations

PURPOSE

The effect of antiglaucomatous agents on conjunctiva used for various durations evaluated histopathologically.

METHODS

Conjunctiva biopsies were taken in 19 Mayis University Faculty of Medicine Ophthalmology Department from 31 eyes of 30 patients who underwent filtration surgery after a period of antiglaucomatous agent use and examined under light microscope. The results were compared with the results of conjunctival biopsies from 10 similar aged patients undergoing retinal detachment of cataract surgery and with no other ocular pathology.

RESULTS

Five of the cases were using antiglaucomatous treatment for two months (Group A), four cases for two to 12 months (Group B) and 22 cases for more than 12 months (Group C) before the surgery. Four cases were using a beta blocker only, eight cases beta blocker + sympathomimetic or beta blocker + myotic and the remaining 19 cases were using a combination of beta blocker + sympathomimetic + myotic. Histopathologic evaluation with light microscope showed no pathologic change in group A, but, subepithelial increase of lymphocytes, mast cells, macrophages and fibroblasts in group C.

CONCLUSIONS

It was detected that subconjunctival inflammatory reaction increases as the number of antiglaucomatous agents and the treatment duration increase. These changes might be considered as risk factors that decrease the success rate of filtration surgery.

The preclinical pharmacology of dorzolamide hydrochloride, a topical carbonic anhydrase inhibitor

Dorzolamide hydrochloride (S,S-5,6-dihydro-4H-4-ethylamino-6-methylthieno [2,3-b]thiopyran-2-sulfonamide-7,7-dioxide HCl; MK-507; L-671,152) is a water-soluble, potent inhibitor of human carbonic anhydrase isoenzymes II and IV in vitro, the respective IC50 values being 0.18 nM and 6.9 nM. In contrast, it was found to be a much weaker inhibitor of human carbonic anhydrase isoenzyme I (IC50 value of 600 nM). The topical administration of one 50 microliters drop of 0.5%, 1% and 2% solutions of dorzolamide maximally lowered the intraocular pressure (IOP) of glaucomatous monkeys by 22%, 30% and 37%, respectively. Good ocular hypotensive activity was also observed in ocular normotensive and hypertensive rabbits. Its site of action was within the eye, and the reductions in IOP in both species was achieved via decreased aqueous humor inflow. The duration of action of 2% dorzolamide was shorter than that of 0.5% timolol in glaucomatous monkeys. The IOP lowering activity of timolol in this paradigm was enhanced by the concomitant instillation of dorzolamide. Both acutely and repeatedly administered 2% dorzolamide did not decrease regional ocular blood flow in the rabbit, and the topical instillation of the drug had no adverse effects on the eye of rabbits, dogs and monkeys. Dorzolamide has been approved in a number of countries for use in patients with ocular hypertension or open-angle glaucoma.

Effects of topically applied prostaglandin F2 alpha tromethamine salt on glaucomatous human eyes

Prostaglandin F2 alpha (PGF2 alpha) as its tromethamine salt was topically applied, and hypotensive and other ocular effects were studied, in glaucomatous human eyes. After baseline intraocular pressure (IOP) measurements, 100 micrograms PGF2 alpha tromethamine salt dissolved in 50 milligrams saline was applied to 23 glaucomatous eyes of 20 patients. The pretreatment diurnal IOP values of the same eye served as control group. It was found that in comparison with baseline values, PGF2 alpha caused significant but transient elevation in IOP in the first half-hour (mean 1.95 mm Hg, p < 0.01), but it decreased below baseline values at the first hour. A significant decrease in IOP from baseline was observed at the 2nd hour (p < 0.05), which became more prominent between the 4th and 24th hours (p < 0.001). PGF2 alpha produced a maximal IOP reduction of 10.21 mm Hg at the 12th hour (p < 0.001). The IOP differences between PGF2 alpha-treated and control groups were significant between the 4th and 24th hours (p < 0.001), with the maximal IOP difference of 9.21 mm Hg at the 12th hour (p < 0.001). PGF2 alpha caused marked conjunctival hyperaemia in all eyes. Aqueous flare and cellular response were not seen in any of the eyes. Half of the patients experienced ocular smarting or a foreign-body sensation, periocular pain and headache. PGF2 alpha reduced IOP effectively in glaucomatous human eyes.

Pharmacokinetics and intraocular pressure lowering effect of timolol preparations in rabbit eyes

Two timolol preparations, a gel and an eyedrop with a thickening agent, and one commercial eyedrop without a thickening agent, were studied in rabbits. After topical administration of these three preparations in rabbits, aqueous humor was withdrawn and the proteins removed from the samples by precipitation with acetonitrile. Timolol concentrations were determined directly by an HPLC method. The HPLC mobile phase was composed of methanol and 5 mM d-camphorsulfonic acid (in 1% acetic acid) with a ratio of 49:51 (v/v). A reversed phase C18 column was used to separate samples with a flow rate of 0.8 mL/min and a UV detector set at 284 nm. A two-compartment pharmacokinetic model was used to fit the aqueous humor level for determining the drainage (kd) and absorption rate constants (ka) in the precorneal area as well as the elimination rate constant (ke) of timolol in aqueous humor. For ka +kd, the eyedrop without a thickening agent had the highest value (0.160 min-1), followed by the eyedrop with a thickening agent (0.030 min-1), and the gel had the lowest value (0.009 min-1). It suggests that the gel has a longer retention time in eyes to improve ocular bioavailability and decrease side effects. The AUC0 approximately infinity for the aqueous humor profile with time coordinates were 4142, 2974, and 1604 micrograms min/mL, for the gel, the eyedrop with a thickening agent, and the eyedrop without a thickening agent, respectively. In another study, timolol preparations were also topically administered in alpha-chymotrypsin-induced glaucoma rabbits for determining the lowering effect on intraocular pressure (IOP). The durations of depressing IOP for the gel, the eyedrop with a thickening agent, and the eyedrop without a thickening agent were 24, 14 and 10 hrs, respectively. Thus, the gel preparation has a longer duration and a higher ocular bioavailability which might be further developed in the treatment of open-angle glaucoma.

Deep sclerectomy: results with and without collagen implant

PURPOSE

To study the need, the safety and the success rate of collagen implant in eyes that underwent deep sclerectomy, a new non penetrating filtration procedure, we compared the results of deep sclerectomy with (DSCI) and without (DS) collagen implant.

METHODS

Of 168 patients (168 eyes) with various types of medically uncontrolled open angle glaucoma, 86 (86 eyes) underwent DSCI, and 82 (82 eyes) underwent DS. Visual acuity, slit lamp examination, intraocular pressure (IOP) measurements were performed before surgery and prospectively at days 1 and 7 and months, 1, 2, 3, 6, 9, 12, 15, 18, and 24 after surgery. Deep sclerectomy was performed according to Kozlov's original technique. The collagen implant drainage device was radially secured in the center of the deep sclerectomy dissection.

RESULTS

The mean follow-up period was 9.7 +/- 6.5 months for DSCI, and 9.0 +/- 4.8 months for DS. The mean preoperative IOP was 26.9 +/- 8.8 mmHg for DSCI and 25.8 +/- 8.5 mmHg for DS. The mean postoperative IOP and visual acuity were similar between the two groups. Complete and qualified success rates were better when the collagen implant was used (Log-Rank test: p = 0.0002 and 0.033 for complete and qualified success respectively). The need for postoperative glaucoma medications was significantly lower when the collagen implant was used (0.2 +/- 0.5 versus 0.5 +/- 0.7 medication per patient in the DSCI and DS respectively, Student's t test: p = 0.0038). There was significantly less bleb fibrosis when the collagen implant was used (2% and 11% in DSCI and DS respectively, p = 0.029).

CONCLUSION

The collagen implant device is safe, increases the success rate of deep sclerectomy, and lowers the need for postoperative glaucoma medications.

Effects of topical administration of 0.5% apraclonidine on intraocular pressure, pupil size, and heart rate in clinically normal dogs

OBJECTIVE

To evaluate the effect of 0.5% apraclonidine on intraocular pressure (IOP), pupil size, and heart rate in clinically normal dogs.

DESIGN

Randomized masked saline-controlled case study.

ANIMALS

Nine clinically normal conditioned adult dogs of either sex.

PROCEDURE

Normal diurnal variation in IOP, pupil size, and resting heart rate were determined from 7 AM to 7 PM (day 1). These measurements were repeated on day 2 after topical application of 60 microliters of 0.5% apraclonidine to 1 randomly chosen eye of each dog. The contralateral eye received saline solution.

RESULTS

Compared with the saline-treated fellow eye, mean IOP in the apraclonidine-treated eye was significantly reduced (3.0 mm of Hg, 16%) 8 hours after treatment. Because of mild day-to-day variations in IOP, however, IOP in the apraclonidine-treated eye on day 2 was not significantly different from day-1 baseline values obtained from the same eye. Significant mydriasis (2.1 mm, 29.7%), persisting for up to 8 hours, occurred in apraclonidine-treated eyes. Although apraclonidine did not significantly alter heart rate when all 9 dogs were viewed as a group, 4 dogs experienced a 9 to 19.5% reduction in heart rate 2 hours after treatment. Mild blanching of the conjunctiva occurred in apraclonidine-treated eyes.

CONCLUSIONS

Apraclonidine lowered IOP and, in contrast to cats where it causes miosis, induced mydriasis in dogs. Although heart rate generally is unchanged, it may be reduced in select individuals.

CLINICAL RELEVANCE

Topically applied 0.5% apraclonidine may be a useful adjunct to other antiglaucoma treatment modalities in dogs, but is unlikely to be effective as the sole agent in most forms of canine glaucoma.

Use of bifemelane hydrochloride in improving and maintaining the visual field of patients with glaucoma

We investigated the change of visual fields in 40 patients with primary or secondary glaucoma. No limitations were placed on the type of angular glaucoma (ie, open or closed). The intraocular pressure of the patients had been controlled at < 20 mm Hg for 2 years before the study, and patients with normal-tension glaucoma also were included. We evaluated the effect of 48 months of treatment with bifemelane hydrochloride, 150 mg/d in three divided doses, on 20 patients with glaucoma. The control group included 20 glaucoma patients whose intraocular pressure had been controlled at < 20 mm Hg for 2 years before the study by the instillation or oral administration of an intraocular hypotensive agent. They had not received any oral agent, such as a cerebral circulation metabolism activator. Results showed that the visual field was improved in 14 (70%) of 20 patients who received bifemelane hydrochloride, whereas the visual field was improved in 4 (20%) of 20 patients in the control group. More patients in the bifemelane hydrochloride group had improved visual fields than in the control group; differences between groups were significant. In addition, an evaluation of the visual field with the use of the Kosaki and Inoue classification showed improvement in all patients in stages IIa to V. We conclude that this drug is useful for maintaining and improving the disturbed visual field of patients in whom the intraocular pressure can be maintained at < 20 mm Hg and in patients who can tolerate 150 mg/d in three separate doses.

Surgical results and complications of trabeculectomy with intraoperative application of mitomycin C

Trabeculectomy is reportedly less effective in aphakic eyes, secondary glaucoma, juvenile patients, and eyes with a history of unsuccessful glaucoma surgery. We evaluated the surgical effects and complications of trabeculectomy with the adjunctive use of mitomycin C, an antiproliferative drug, in a number of refractory cases. Forty patients (50 eyes) with refractory glaucoma were treated with trabeculectomy and the adjunctive use of mitomycin C and were followed postoperatively for at least 3 months. The mean follow-up period was 13.6 +/- 7.5 months (range: 3 to 31 months). In 43 eyes (86%), intraocular pressure was well controlled at < or = 21 mmHg. Complications included corneal epithelial damage (30 eyes), shallow anterior chamber (20 eyes), hyphema (19 eyes), choroidal detachment (18 eyes), leakage of aqueous humor from the conjunctival wound (4 eyes), and endophthalmitis (1 eye). The results of trabeculectomy with intraoperative use of mitomycin C in this series of procedures demonstrates that this can be a useful and effective treatment; however, mitomycin C may cause transient decreased visual acuity due to inhibited wound healing and the resultant overfiltration.

Comparison of the ocular beta-blockers

OBJECTIVE

To compare the similarities and differences among the ocular beta-blockers. Important considerations when comparing these agents are the differences in systemic adverse effects, local tolerability, and cost.

DATA SOURCE

Information was retrieved from a MEDLINE search of the English-language literature and bibliographic reviews of review articles. Index terms included beta-blockers, glaucoma, timolol, levobunolol, betaxolol, metipranolol, and carteolol.

STUDY SELECTION

Emphasis was placed on eyedrop studies, as well as properly designed and executed clinical trials that assessed dosage, dosing interval, therapeutic response, adverse effects, and cost.

DATA EXTRACTION

Data from several studies were evaluated according to the study design, therapeutic response, and adverse effects.

DATA SYNTHESIS

Timolol maleate, levobunolol, metipranolol, and carteolol have similar effectiveness in lowering intraocular pressure; however, levobunolol and timolol gel forming solution may have an advantage of once-daily dosing. Studies have not been published comparing the clinical efficacy of timolol hemihydrate with that of other ocular beta-blockers. Metipranolol is cost effective in treating primary open-angle glaucoma; however, it has been associated with more ocular burning, stinging, and granulomatous anterior uveitis than other agents. The intrinsic sympathomimetic activity of carteolol has not yet displayed a definite advantage over the other agents in terms of optic disk perfusion and systemic adverse effects. The control of intraocular pressure with betaxolol has not always been as good as with timolol; however, betaxolol has some advantages over timolol and the other topical beta-blockers in terms of systemic adverse effects.

CONCLUSIONS

Considering cost, efficacy, and safety, timolol maleate is the recommended formulary agent because the other agents cannot consistently show an outstanding advantage.

An ultrasound biomicroscopic study of filtering blebs after mitomycin C trabeculectomy

PURPOSES

To investigate the relation between filtering bleb function and ultrasound biomicroscopic images, and to establish a new classification system for filtering blebs according to these images.

METHODS

After trabeculectomy with mitomycin C, the filtering blebs of 117 eyes from 117 patients with various types of glaucoma were examined using ultrasound biomicroscopy. Four parameters of the images-intrableb reflectivity, visibility of the route under the scleral flap, formation of a cavernous fluid-filled space, and bleb height-were correlated with the level of intraocular pressure (IOP).

RESULTS

Reflectivity inside the bleb and visibility of a route under the scleral flap were highly associated with IOP control. Blebs were classified into four categories according to the four measured parameters: type L (low-reflective), type H (high-reflective), type E (encapsulated), and type F (flattened). Eyes with good IOP control had mainly type L blebs. Type E and type F blebs were seen mostly in eyes requiring additional medication.

CONCLUSION

The structure inside a filtering bleb is visible by ultrasound biomicroscopy, and bleb function is significantly associated with its ultrasound biomicroscopic image in eyes trabeculectomized with adjunctive mitomycin C.

Long term effect of apraclonidine

AIMS

To evaluate the effect of the chronic use of apraclonidine 0.5% on the intraocular pressure (IOP) of patients with glaucoma; also, to study the side effect profile of this drug when used chronically.

METHODS

All patients who had uncontrolled IOP, who were either already on glaucoma medications, or who were intolerant of other glaucoma medications were enrolled. A total of 185 patients were started on apraclonidine 0.5% two to three times a day in one eye.

RESULTS

Follow up extended to 35 weeks. The mean difference in IOP between treated and control eyes was 2.1 (SD 5.0) mm Hg. A similar IOP lowering effect was obtained comparing IOP difference from baseline in the treated eye only.

CONCLUSION

By the end of the follow up period, 46% of patients were still on the medication. The drug was stopped in 23% of patients because of side effects and in 31% of patients because of failure to lower IOP significantly.

Syntheses and molecular structures of 3-N, N-di-n-propylamino-2-chromanones as new analogues of dopamine

A series of 3-N,N-di-n-propylamino-2-chromanones were synthesized as dopamine analogues. The lactone ring was introduced as a means to reduce their propensity to cross the blood-brain barrier and to avoid central side effects, rendering these compounds potentially useful for the treatment of glaucoma. Pharmacological activities were determined in vitro on rat striatum, by examining their capacity to displace the specific binding of the labeled dopaminergic ligand 3H sulpiride or 3H spiperone and 3H SCH 23390 for D2 and D1 sites, respectively. Compound 6a showed a weak dopaminergic activity on D2-receptors and no affinity for D1-receptors, which can be explained, at least in part, by a weak pKa and the presence of an internal hydrogen bonding. Furthermore, computer molecular modelling studies showed that the aromatic ring of 6a was negatively charged in contrast to the classical D2-agonists aminotetralin derivatives, hampering a possible interaction with a negatively charged area of the D2-receptor. These results, taken together, can account for the moderate dopaminergic activities exhibited by these lactone derivatives.

[Surgical effects of trabeculotomy after long-term topical antiglaucoma medications]

We retrospectively analyzed the effects of long-term topical antiglaucoma therapy on the results of trabeculotomy. We studied 83 eyes with 76 primary open angle glaucoma and 7 eyes with capsular glaucoma, each of which had undergone trabeculotomy alone and none of which had a history of laser trabeculoplasty or glaucoma surgery. The outcome of trabeculotomy was assessed after a minimum follow-up of 12 months. Using a life-table method, there was no significant difference in the outcome of trabeculotomy between groups divided by duration and type of preoperative topical therapy. There was not statistically significant difference in the intraocular pressure reduction between the groups of long or short duration of topical therapy. We concluded that the duration and type of topical antiglaucoma medications had no significant effect on the outcome of trabeculotomy.