Conjunctival Fibrosis after Application of Mitomycin C: An Animal Experimental Study

Mitomycin C (MMC) is widely used as an antimetabolite to minimize scarring of filtering blebs. Its effectiveness has been demonstrated in several clinical studies. The drug's mechanism of action is attributed to its antiproliferative effect on the subconjunctival cells, reducing the wound healing response. We placed sponges soaked with various concentrations of MMC, from 0.05 to 1.0 mg/ml, under the conjunctiva of 18 rabbits. Four weeks later, there was marked concentration-dependent scarring of the substantia proppria of the conjunctiva. Macrophages were more numerous in treated eyes, as determined by immunohistochemistry. The reason for MMC-related fibrosis in this animal model is not clear but may be related to the substances toxic effects. Whether it is only present in rabbits remains to be clarified.

Morphological and microstructural investigations of composite dielectrics for energy storage

Efficient composite dielectrics can be created by combination of phase free Ba(Ti_(1−x)Ge_x)O₃ nanoparticles, and an inorganic BBS glass matrix, consisting of BaO, B₂O₃ and SiO₂.

Enhanced dielectric properties of sol–gel-BaTiO3/P(VDF-HFP) composite films without surface functionalization

BaTiO₃–P(VDF-HFP) composite films without surface functionalization show a tenfold increase of the relative permittivity compared to the pure polymer.

Experimental observation of a torus doubling of a metal/ferroelectric film/semiconductor capacitor

A metal-ferroelectric-semiconductor (MFS) structure was used as a nonlinear capacitor in a series resonance circuit. The following materials were used as components of the MFS structure: aluminium as the metal electrode, Bi4Ti3O12 film as the ferroelectric, and p-type silicon as the semiconductor. The system was driven by a single frequency at suitably chosen amplitudes. Besides the sequences of period-doubling bifurcations which were already observed in the series resonance circuit with a pure ferroelectric capacitor, we found regions with torus-doubling bifurcations by varying the frequency of the driving voltage at suitably high amplitudes. Comparing the behaviour of the series resonance circuit with a pure ferroelectric capacitor and with the MFS structure, we attribute the reason for the new effect of torus doubling to the properties of the ferroelectric-semiconductor boundary layer.

Microprocessor controlled compliance monitor for eye drop medication

BACKGROUND/AIMS

The effectiveness of a self administered eye drop medication can only be assessed if the compliance is known. The authors studied the specificity and sensitivity of a new microprocessor controlled monitoring device.

METHODS

The monitoring system was conducted by an 8 bit microcontroller for data acquisition and storage with sensors measuring applied pressure to the bottle, temperature, and vertical position. 10 devices were mounted under commercial 10 ml eye drops. Test subjects had to note down each application manually. A total of 15 applications each within 3 days was intended.

RESULTS

Manual reports confirmed 15 applications for each of the 10 bottles. The monitoring devices detected a total of 149 events; one was missed; comprising a sensitivity of 99%. Two devices registered three applications, which did not appear in the manual protocols, indicating a specificity of about 98%. Refrigerated bottles were correctly identified. The battery lifetime exceeded 60 days.

CONCLUSION

The new monitoring device demonstrated a high reliability of the collected compliance data. The important, yet often unknown, influence of compliance in patient care and clinical trials shall be illuminated by the new device. This may lead to a better adapted patient care. Studies will profit from a higher credibility and results will be less influenced by non-compliance.

[The effect of brimonidine on the pupillary reflex. A pupillographic study in healthy volunteers]

PURPOSE

The effect of brimonidine in comparison with acetazolamide on pupillary reflex was investigated in 18 volunteers.

METHODS

Infrared pupillography was performed with white diode light of 200 ms duration to measure pupil diameter, constriction latency, reaction time, constriction amplitude, and relative constriction amplitude. The measurements were performed according to a fixed schedule including a phase without medication to determine the baseline level. Data were analyzed by Student's paired t-test.

RESULTS

Application of brimonidine and acetazolamide led to a significantly reduced intraocular pressure as well as static and dynamic differences in the pupillary reflex. The pupil diameter measurements were significantly smaller after both medications in comparison to baseline. The reduction of pupil diameter after brimonidine led to significantly reduced contraction amplitude and prolonged latency.

CONCLUSION

Application of brimonidine leads to significant miosis, which might due to the affinity to alpha(2)-receptors with reduction of noradrenaline release in the synapse. This effect may play a role in a higher decrease of intraocular pressure by increasing aqueous humor outflow in comparison to clonidine and apraclonidine, but further investigations are required.

Comparaison de deux formes d’application de médicaments : collyre versus lyophilisat

PURPOSE

The ocular bioavailability of a single application of a triple dose of sodium fluorescein to the human anterior segment of the eye was studied as a novel drug delivery device.

METHODS

The lyophilisate contained a fluorescein dose of 204 microg corresponding to three conventional, preservative-free eye drops of 40 microl Fluorescein SE Thilo 0.17% (68microg each) (Alcon). A single lyophilisate was applied to one eye of 22 healthy volunteers (+1 min) and three conventional eye drops (+1, 16, 31 min) were applied to their fellow eye. In this randomized, open label study, fluorophotometry was performed (Fluorotron Master IItrade mark, Ocumetrics, Mountain View, California, USA) before and +15, 30, 45, 60, 120, 180, 240, 300, 360, 420 min after application. The fluorescein concentrations of the corneal stroma (C), mid-anterior chamber (AC) were analyzed by paired t-test.

RESULTS

Cornea and AC mean values (ng/ml) were significantly higher (p < 0.018, paired t-test) in the lyophilisate group up to 7 h after application, with the exception of +45 min. The mean fluorescein bioavailability from the lyophilisate was up to 11 times higher in the C and up to 8.7 times higher in the AC compared with the three preservative-free eye drops.

DISCUSSION

For the first time a triple dose was delivered to the human eye with a single lyophilisate application. Significantly better bioavailability was achieved in the C and AC for up to 7 h using this new device. The treatment of glaucoma, bacterial, viral, and fungal infections, as well as dry eye syndrome, for example, will be improved using lyophilisate.

Optic nerve head morphometry in healthy adults using confocal laser scanning tomography

BACKGROUND/AIMS

To study the optic nerve head (ONH) characteristics in a cross sectional study with confocal laser scanning tomography using the Heidelberg retina tomograph (HRT I) and thereby to obtain a new HRT database for comparison of healthy and glaucomatous eyes.

METHODS

White adults with no history of ocular pathology were eligible for the study. The examination comprised: assessment of visual acuity; slit lamp examination of the anterior and posterior segment; Goldmann applanation tonometry; computerised perimetry, and optic nerve head tomography with HRT. Eyes with ocular pathology were excluded. Mean (standard deviation, SD) and difference between right and left eye (RE-LE) were calculated for HRT I measurements. Differences in mean topographic parameters between male and female participants and between the age quartiles were analysed. The study included 1764 eyes of 882 healthy adults (154 females and 728 males, mean age of 46.8 (SD 8.6) years). The population investigated was larger and older in comparison with similar studies using confocal laser scanning tomography.

RESULTS

With HRT I, a mean disc area of 1.82 (SD 0.39) mm(2), a mean cup area of 0.44 (SD 0.32) mm(2) and a mean cup:disc area ratio of 0.22 (SD 0.13) was observed. Right eyes showed a larger mean retinal nerve fibre layer thickness (RNFLT) (0.263 (SD 0.066) mm) compared with left eyes (0.252 (SD 0.065) mm, p<0.001). Higher values in younger volunteers (mean age 35.7 years) in comparison with elderly participants (mean age 59.1 years) were noted for disc area (1.84 mm(2)v 1.78 mm2) and mean RNFLT (0.263 (SD 0.06) mm v 0.249 (SD 0.07) mm) but were not significant (p>0.01). The presented results differ from published data on ONH measurements of healthy volunteers with different techniques.

CONCLUSION

The observed differences in ONH measurements between left and right eyes seem not to be of clinical importance. This is also true for age or sex dependent changes in ONH topographies. The presented data provide a new basis for comparison of optic disc characteristics between healthy eyes and glaucomatous eyes.

A 12 week study comparing the fixed combination of latanoprost and timolol with the concomitant use of the individual components in patients with open angle glaucoma and ocular hypertension

BACKGROUND

To compare the intraocular pressure (IOP) lowering effect and safety of the fixed combination of latanoprost and timolol with that of the concomitant use of the individual components.

METHODS

A 12 week, double masked, randomised, crossover, multicentre study of patients with open angle glaucoma or ocular hypertension and IOP controlled on ocular hypotensive treatment (mean < or =21 mmHg). Patients received either a once daily morning dose of the fixed combination of latanoprost 0.005% and timolol 0.5% or once daily evening latanoprost 0.005% and twice daily timolol 0.5% for six weeks and then switched to the other combination. The primary efficacy endpoint was the within-patient difference in diurnal IOP between fixed and unfixed treatment combinations after six weeks of treatment; a one sided 97.5% confidence interval (CI) for the mean difference in IOP <1.0 mmHg indicated the fixed combination was not inferior to the unfixed combination. Adverse events were recorded at each visit.

RESULTS

In all, 190 patients were included in observed cases analyses (93 fixed to unfixed combination; 97 unfixed to fixed combination). Mean IOP at baseline was 16.9 mmHg in both groups. The mean diurnal IOP was 17.0 mmHg after fixed combination treatment and 15.9 mmHg after unfixed combination therapy (p<0.0001). The difference in mean within-patient diurnal IOP was 1.1 mmHg favouring the unfixed combination (95% CI 0.8 to 1.4 mmHg). Both treatments were tolerated well.

CONCLUSIONS

Although the primary efficacy endpoint was not met, once daily administration of the fixed combination of latanoprost and timolol was found to be safe and effective. The fixed combination provides a convenient alternative to the three instillations required with the individual components.

Bioavailability of fluorescein from a new drug delivery system in human eyes

AIM

To assess the ocular bioavailability of fluorescein from a novel drug delivery system compared with one single preservative free eye drop.

METHODS

Part A: In a randomised study 10 volunteers applied the lyophilisate to one eye and a conventional fluorescein eye drop to the fellow eye. Fluorophotometry was performed before and every 2 minutes up to 30 minutes after application in the cornea and anterior chamber. Part B: Another 10 volunteers applied each form of the application. Fluorophotometry was performed before, +2 minutes, and at +8, +10, +12 hours. The dose corresponding to a single fluorescein dose of the lyophilisate was 68 l microg fluorescein SE 0.17%.

RESULTS

Part A: During the first 30 minutes after administration of the preservative free eye drop of 40 microg the corneal and anterior chamber concentration means were up to 16 times higher in eyes treated with the lyophilisate. Part B: 8-12 hours after application the mean fluorescein concentration in the cornea of the lyophilisate group was two times higher than at baseline. Eyes treated with eye drops had baseline values at +8, +10 and +12 hours.

CONCLUSION

A significantly better bioavailability was achieved in human eyes by using lyophilisate compared with the same dose from a conventional eye drop. Lyophilisates are a favourable alternative to conventional eye drops since they have no preservatives, higher long term stability, no pH adjustment, and easy handling.

Persistency and clinical outcomes associated with latanoprost and beta-blocker monotherapy: evidence from a European retrospective cohort study

PURPOSE

To evaluate persistency (time on initial therapy) and the clinical impact of latanoprost versus beta-blocker monotherapy in treating glaucoma.

METHODS

This observational, multicenter, retrospective medical chart review study conducted in four European countries included patients with primary open-angle glaucoma or ocular hypertension who began their first glaucoma treatment with latanoprost or a beta-blocker between November 1996 and November 1998. Persistency and glaucoma-related clinical outcomes data were abstracted for the 2 years following treatment initiation.

RESULTS

In all, 260 patient charts were analyzed (94 latanoprost, 166 beta-blocker). Patients in the latanoprost group stayed on therapy twice as long as those who received a beta-blocker (p < 0.0001). After adjusting for baseline characteristics, patients receiving a beta-blocker as initial therapy were 3.8 times more likely to change therapy than those initially treated with latanoprost (p < 0.0001). Patients in the latanoprost group also experienced greater mean decreases in intraocular pressure (IOP) than those receiving a beta-blocker (7.4 mmHg versus 4.6 mmHg, respectively; p < 0.0001), and fewer had worsened optic nerve head excavation (1.7% versus 14.2%, respectively; p < 0.05) by the time of their first therapy change or last study visit, whichever came first.

CONCLUSIONS

Over a 2-year period, latanoprost was associated with significantly greater persistency and better clinical IOP outcomes compared with beta-blocker therapy.

Photodynamic modulation of wound healing in glaucoma filtration surgery

AIM

To report a clinical pilot study investigating photodynamic therapy (PDT) in combination with glaucoma filtration surgery. BCECF-AM was used as the photosensitising substance. The clinical safety and tolerability of BCECF-AM, and its efficacy in controlling postoperative intraocular pressure (IOP) were assessed.

METHODS

Before trabeculectomy (TE), 42 consecutive eyes of 36 glaucoma patients received one subconjunctival injection of 80 micro g BCECF-AM (2,7,-bis- (2-carboxyethyl) -5- (and-6) -carboxy-fluorescein, acetoxymethyl-ester) followed by an intraoperative illumination with blue light (lambda = 450-490 nm) for 8 minutes. Antifibrotic efficacy was established as postoperative IOP reduction of >20% and/or an IOP constantly < 21 mm Hg without antiglaucomatous medication. Follow up of the filtering bleb was documented by slit lamp examination.

RESULTS

Eyes had mean 1.1 preoperative surgical interventions (filtration and non-filtration glaucoma surgery). Mean preoperative IOP was 31.6 (SD 9.7) mm Hg. Patients were followed for mean 496 days (range 3.5-31.8 months). Of the 42 eyes, 25 eyes had an IOP decreased to 15.8 (3.4) mm Hg without medication (complete success: 59.5%; p<0.001; t test). Seven eyes showed good IOP reduction < 21 mm Hg under topical antiglaucomatous medication (qualified success: 16.7%). 10 eyes failed because of scarring within 2-67 weeks (23.8%). Clinical follow up examinations revealed no local toxicity, no uveitis, and no endophthalmitis.

CONCLUSIONS

This method is a new approach in modulating postoperative wound healing in human eyes undergoing glaucoma filtration surgery. The data of the first human eyes combining TE with PDT underline the clinical safety of this method and its possible potential to prolong bleb survival.

A comparative bioavailability study of three conventional eye drops versus a single lyophilisate

AIM

To study the ocular bioavailability of a triple dose, single application of sodium fluorescein to the human anterior segment from a novel drug delivery device.

METHODS

In a randomised, open label study 22 healthy volunteers applied a single lyophilisate to one eye (+1 minute) and three conventional eye drops (+1, 16, 31 minutes) of fluorescein ophthalmic solution to the fellow eye. The fluorescein dose of the lyophilisate was 204 mg corresponding to three conventional, preservative-free eye drops of 40 ml fluorescein SE Thilo 0.17% (68 micro g each) (Alcon). Fluorophotometry was performed (Fluorotron Master II Ocumetrics, USA) before and +15, 30, 45, 60, 120, 180, 240, 300, 360, 420 minutes after application. The fluorescein concentrations of the corneal stroma and mid-anterior chamber were analysed by paired t test.

RESULTS

Cornea and anterior chamber mean values (ng/ml) were significantly higher (p<0.018, paired t test) in the lyophilisate group up to 7 hours after application with the exception of +45 minutes. The mean fluorescein bioavailability from the lyophilisate was up to 11 times higher in the cornea and up to 8.7 times higher in the anterior chamber compared with the three preservative-free eye drops.

CONCLUSION

A triple dose was delivered to the human eye with a single lyophilisate application for the first time. A significantly better bioavailability was achieved in the cornea and anterior chamber for up to 7 hours by means of drug application with lyophilisates. The application of medications by means of the lyophilisate will improve the treatment of, for example, glaucoma, bacterial, viral and fungal infections, as well as dry eye syndrome.

Lyophilisates for drug delivery in ophthalmology: pharmacokinetics of fluorescein in the human anterior segment

AIMS

To assess the ocular bioavailability of fluorescein from a novel water free, freeze dried ophthalmic drug delivery system compared to conventional preservative-free fluorescein eye drops.

METHODS

Sodium fluorescein 0.17% was dissolved in an aqueous solution of hydroxypropylmethyl cellulose 1.0% (HPMC), deposited on sterilised flexible hydrophobic poly(tetrafluoroethylene) (PTFE) carrier strips and freeze dried under aseptic conditions. The fluorescein dose of the lyophilisate was 68 micro g, corresponding to a single conventional drop of 40 micro l fluorescein 0.17% solution. In a randomised, open label study 12 healthy volunteers applied the lyophilised fluorescein to one eye and one drop of conventional fluorescein ophthalmic solution to the fellow eye. Fluorophotometry measurements of fluorescein concentrations in the anterior segment were performed with the Fluorotron Master II (Ocumetrics, USA) before and +15, 30, 45, 60, 120, and 180 minutes after application.

RESULTS

At all times anterior chamber fluorescein concentration was greater in the lyophysilate treated eye than the solution treated eye. The magnitude of this difference ranged from 2-5.3 times and was statistically significant.

CONCLUSION

The greater intraocular bioavailability of fluorescein from the lyophilisate relative to the solution suggests that it may be a useful method for delivering substances to the eye.

The efficacy and safety of unfixed and fixed combinations of latanoprost and other antiglaucoma medications

Adjunctive therapy for the management of glaucoma is commonly used. Unfixed combinations of the prostaglandin analog latanoprost and other glaucoma medications have been demonstrated to effectively lower intraocular pressure (IOP). The range of reported additional reductions in IOP compared to a monotherapy baseline are as follows: latanoprost-timolol (13-37%), latanoprost-pilocarpine 2% (7-14%), latanoprost and carbonic anhydrase inhibitors (15-24.1%), and latanoprost and dipivefrin (15-28%). There is a fixed combination of latanoprost (0.005%) and timolol (0.5%) that has been investigated in Phase III trials in Europe and the United States. In these trials, it was noted that the efficacy of the fixed combination was superior to either of the monotherapy components. After 12 months of follow-up of patients on fixed combination, there was no evidence of long-term drift. The new formulation appears to be safe and does not demonstrate any more side effects than either of the components. The convenience of a fixed combination may enhance patient compliance. Unfixed combination therapy with latanoprost and other antiglaucoma medications and the fixed combination formulation of latanoprost and timolol provide an effective and safe option for lowering IOP in glaucoma patients.

Development of a completely encapsulated intraocular pressure sensor

A completely encapsulated intraocular pressure (IOP) sensor equipped with telemetric signal and energy transfer is introduced integrated into a silicone disc for implantation into the eye. After implantation into enucleated pig eyes and into rabbit eyes in vivo, the IOP was recorded and compared to established techniques of IOP measurement. Pressure chamber tests showed that the sensor functioned correctly after biocompatible encapsulation in polydimethylsiloxane. In vivo and in vitro tests in rabbit and pig eyes demonstrated that the implanted system worked with the same precision as established techniques for IOP determination. The correlation between the measurements with the implanted device and pneumotonometry in several experiments was between 0.9 and 0.99. This device serves as a functioning model for the realization of a telemetric IOP sensor for integration into an artificial intraocular lens. Such a device will open new perspectives, not only in the management of glaucoma, but also in basic research for mechanisms of glaucoma.

Ocular concentrations of mitomycin C using different delivery devices

Hypotony and its sequelae are a frequent complication of trabeculectomies performed with mitomycin C (MMC), possibly related to intraocular toxicity of the substance. In an animal model with rabbits, we used different devices for the application of MMC and measured extra- and intraocular concentrations by HPLC. In addition, the concentrations of MMC remaining in the devices were determined. The devices were (1) a regular surgical sponge, (2) a scleral shield, (3) a presoaked soft contact lens, (4) a soft contact lens with MMC application, and (5) subconjunctival injection. Ocular concentrations of MMC were similar within the first 4 groups and were highest in the last. The measurements suggest that MMC penetrates intraocularly regardless of the device used. The variability of remaining MMC concentrations in the devices was lowest in the soft contact lenses suggesting an improved delivery system compared to the usually used surgical sponges.

[Long-term follow-up of 700 trabeculectomies]

BACKGROUND

A major focus of our study was to determine the value of postoperative intraocular pressure (IOP) in predicting the outcome of trabeculectomy (TE).

PATIENTS AND METHODS

The medical charts of 547 patients undergoing glaucoma filtering surgery at the Department of Ophthalmology of the University of Cologne from 1987 to 1996 were reviewed. The eyes with congenital glaucoma and those treated with anti-metabolites were excluded.

RESULTS

Defining the qualified criteria for success of trabeculectomy as an IOP </21 mm Hg throughout the entire study period, no evidence of progressive disc damage or further visual field loss, no decrease in visual acuity and no additionally required surgical intervention due to glaucoma, there was a success rate of 44.4%. In 50% the tonometric failure took place within the first 34 days trabeculectomy. No significant difference in survival by sex (p = 0.53), surgical technique, limbal versus fornix-based flap (p = 0.28) and by type of glaucoma (p = 0.26) was shown. But the patient group with prior argon laser trabeculoplasty had a significant lower success rate in terms of normalization of IOP (p = 0.03). There was no significant difference in the outcome of trabeculectomy between the first and second eye.

CONCLUSION

The identification of patients at risk of failure in terms of IOP in the early post-operative period is possible, thus, closer follow-up and early medical or surgical intervention may be indicated. Should trabeculectomy be the therapy of first choice in the early stage of glaucoma and in case of failure in the first eye, this would allow options, such as the use of anti-metabolites in the second eye.

[The effect of latanoprost 0.005% on pupillary reaction of the human eye]

PURPOSE

Infrared pupillography was performed to investigate the effect of one week topical treatment with the prostaglandin analogue Latanoprost 0.005% on pupillary reflex to light stimuli in glaucomatous human eyes.

METHODS

Infrared pupillography using the compact integrated pupillograph was performed in 20 glaucomatous eyes of 11 patients. After 10 minutes dark adaptation one pupil was stimulated with a blue, yellow and white diode light of 100 ms duration. Measurements of pupil diameter, constriction latency, constriction amplitude and relative constriction amplitude were taken twice for each light source in a time interval of 15 seconds. After a 2 week wash-out period the measurements were performed from 8:00 to 10:00 a.m. before and one week after topical treatment with Latanoprost 0.005% applied as single dose once in the evening.

RESULTS

The measurements after 1 week treatment with Latanoprost showed a significantly smaller pupil diameter for blue (p = 0.044) and white stimulus (p = 0.039) and the latency was significantly reduced (p = 0.029) as well.

CONCLUSIONS

Although the statistical analysis shows some small significant differences in pupil diameter and constriction latency there were no clinical signs of changes in pupillary response due to Latanoprost. The system turned out as easy to use and showed reliable measurements during the study. How far latanoprost may lead to miosis and a decrease of constriction latency has to be investigated in further studies with larger study populations. Other topics concerning drug influence, diurnal rhythm and glaucomatous damage in pupillary light reaction will be investigated in the near future.

The additive intraocular pressure-lowering effect of latanoprost 0.005% daily once and pilocarpine 2% t.i.d. in patients with open-angle glaucoma or ocular hypertension. a 6-month, randomized, multicenter study. German Latanoprost Study Group

PURPOSE

To compare the additional intraocular pressure-lowering effect of latanoprost 0.005% administered once daily with that of pilocarpine 2% administered three times daily in patients with primary open-angle glaucoma or ocular hypertension currently on monotherapy with timolol 0.5% twice daily.

METHODS

In a 6-month, multicenter, randomized, open-label study 242 patients with POAG or OH whose IOP was not controlled with timolol 0.5% b.i.d. were enrolled. Eyes had not been treated with pilocarpine and latanoprost for at least 2 years. An analysis of covariance with diurnal IOP change from baseline to month 6 for study eyes was performed.

RESULTS

Four patients on latanoprost 0.005% and 35 on pilocarpine 2% did not complete the study (P<0.001). Two hundred and forty patients were included in the intent-to-treat analysis. For both treatments the diurnal IOP reduction after 6 months was statistically significant (P<0.001). IOP (mean+/-SD) was reduced from 23.3+/-2.8 to 17.8+/-2.8 (-5.6) mmHg in the latanoprost 0.005% group and from 23.0+/-3.2 to 18.5+/-2.4 (-4.8) mmHg in pilocarpine 2% t.i.d.-treated eyes. The mean difference of -0.8 mmHg (per protocol, PP) and -1.6 mmHg (intend-to-treat, ITT) was statistically significant (P<0.04, PP; P<0.001, ITT) in favor of latanoprost 0.005%. Two eyes treated with latanoprost showed an iris color change. Thirty-six patients in the latanoprost group and 106 in the pilocarpine 2% group reported ocular adverse events (P<0.001).

CONCLUSION

From the data we conclude that the additivity of latanoprost 0.005% is at least as effective as pilocarpine 2% t.i.d. in reducing IOP when added to eyes currently on monotherapy with timolol 0.5% b.i.d. Latanoprost was better tolerated than pilocarpine 2% eye drops in this study. The increase in iris pigmentation requires further investigation.

Trabeculectomy: a retrospective follow-up of 700 eyes

A major focus of our study was to determine the value of postoperative intraocular pressure (IOP) in predicting the outcome of trabeculectomy (TE). The medical charts of 547 patients undergoing glaucoma filtering surgery at the Department of Ophthalmology of the University of Cologne from 1987 to 1996 were reviewed. The status of the visual field, level of visual acuity, appearance of the bleb, cup/disc ratio and IOP were studied. Pre- and post-operative glaucoma medication was recorded. The eyes with congenital glaucoma and those treated with antimetabolites were excluded. The results are presented with particular emphasis being placed not only on intraocular pressure (IOP) control but also on the progression of glaucomatous damage (deterioration of visual field or disc damage) and the decrease of visual acuity. The tonometric success rate of TE in controlling the IOP < 21 mmHg was 61%. Defining the rigid criteria for success of trabeculectomy as an IOP < 21 mmHg, no further visual field loss, no disc damage and no additionally required surgical intervention due to glaucoma, the success rate decreased to 44%. The results indicate that other factors than normalization of IOP determine the success rate of TE. Should trabeculectomy be the therapy of first choice in the early stage of glaucoma? Should trabeculectomy fail to control the IOP in the first eye, would this allow options, such as the use of antimetabolites in the second eye?

Cellular photoablation to control postoperative fibrosis in filtration surgery: in vitro studies

The purpose of this study was to evaluate the feasibility of cellular photoablation using fluorescence-generated photoreaction products as a method to control postoperative fibrosis in filtration surgery. The fluorescent probe, 2', 7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein, acetoxymethyl ester (BCECF-AM) is a cell membrane permeable compound rendered membrane-impermeable and fluorescent upon cleavage by intracellular esterases. Human scleral and Tenon's capsule fibroblasts were cultured and used as the target cells. Uptake and retention of the probe were determined with a fluorescence multi-well plate reader. Fibroblasts with or without intracellular probe were irradiated under conditions of fluorescence microscopy with diffuse blue light (450-490 nm, 1.68x10(2)mW m(2-1)). The viability of cells was examined by trypan blue exclusion and crystal violet test. To better mimic a wound healing process the effect of cellular photoablation was verified in artificial lesions produced in cultured monolayers loaded with different concentrations of the probe. Uptake and retention of BCECF-AM is dependent on ambient concentration. When incorporated the probe is lethal to those cells exposed to the appropriate photo-irradiation. Cells exposed to BCECF-AM (for 45 min) at a concentration of approximately 10 microm and irradiated for 1 min resulted in 100% cell death. Cellular photoablation in contrast to chemotherapeutic agents acts only on the targeted cells. This method shall be pursued as an alternative therapy to control postoperative fibrosis in filtration surgery.

Cellular photoablation to control postoperative fibrosis in a rabbit model of filtration surgery

AIM

To evaluate the feasibility of cellular photoablation using fluorescence generated photoreaction products as a method to control postoperative fibrosis.

METHODS

The fluorescent probe, 2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein, acetoxymethyl ester (BCECF-AM) is a cell membrane permeable compound rendered membrane impermeable and fluorescent upon cleavage by intracellular esterases. Rabbits (ChBB:CH; n=20) received a unilateral subconjunctival injection of BCECF-AM (40, 70, 80, or 100 microg) 30 minutes before surgery followed by intraoperative illumination with diffuse blue light (450-490 nm; 51.9 x 10(3) cd/m(2)) for 10 minutes. Controls received either the probe or illumination. Antifibrotic efficacy was established by clinical response and histological examination. Clinical response was assessed by comparing intraocular pressure (IOP) between the treated experimental eye and the fellow eye, which served as control. Success was defined by >20% difference in IOP.

RESULTS

IOP was significantly decreased in all groups within 4 days postoperatively. In control groups IOP rose within 10 days to normal levels. This was similar in the group receiving 40 microg of BCECF-AM. In the other groups (subconjunctival injection of 70-100 microg BCECF-AM) IOP was significantly (p < 0.02) decreased for 2-3 weeks. Clinical and histological examination revealed no toxic damage to adjacent tissues.

CONCLUSIONS

Cellular photoablation in contrast with chemotherapeutic agents acts on cells that have incorporated BCECF-AM and have been exposed to light at the appropriate wavelength. Though safety and reliability demand further studies this method might be an useful therapeutic approach to control postoperative fibrosis in humans undergoing filtration surgery.

Self-tonometry with the Ocuton S versus Goldmann tonometry

BACKGROUND

The purpose of the study was to evaluate the acceptance and reproducibility of a new self-tonometer (Ocuton S) and to compare it with the Goldmann applanation tonometer.

METHODS

The Ocuton S was studied in 20 healthy volunteers and 100 patients. After detailed explanation to each individual and a number of test measurements, we studied the reproducibility and accuracy of the Ocuton S in 20 healthy volunteers with and without topical anaesthesia. Acceptance was graded by means of visual analogue scales. Each volunteer had to measure his/her own IOP in three consecutive measurements. The data were compared with Goldmann tonometry at random times. One hundred patients were introduced to the Ocuton S. Either three consecutive self-measurements of IOP were performed and then compared with three consecutive measurements by Goldmann tonometry, or vice versa. This was done randomly.

RESULTS

Forty-one of 100 patients were unable to perform three consecutive measurements with the Ocuton S after at least 15 min introduction time to the device (non-success). Fifty-nine of 100 patients were able to measure their IOP with the Ocuton S. The mean pressure value with the Ocuton S was 23.2+/-8.2 mmHg, compared with Goldmann 18. 4+/-5.7 mmHg. The difference of 5+/-5.7 mmHg was statistically significant (paired t-test p<0.01). The visual analogue scale scores of healthy volunteers (100 mm = maximal comfort, 0 mm = not acceptable), was 72+/-31 in anaesthetised eyes and 39+/-41 mm without anaesthesia.

CONCLUSION

The Ocuton S seems to be an acceptable means for the majority of patients of measuring their IOP at home. Refinement of the accuracy of the device seems necessary.

Morphologic proof of the toxicity of mitomycin C on the ciliary body in relation to different application methods

BACKGROUND

Since postoperative hypotony has been a frequent complication of glaucomatous filtration surgery with adjunctive use of mitomycin C (MMC), the question arises of whether there may be another application method which can minimize this side effect. The purpose of this study was to establish the morphologic side effects of different application methods.

METHODS

MMC 0.2 mg/ml was applied to the episclera of nine eyes of six pigmental rabbits at random via collagen shield (CS), soft contact lens (CL), or lyophilisate (20 microg; LY) for 5 min. Two eyes (controls) had a subconjunctival injection of BSS only. Another control eye was left untreated (no injection). No trabeculectomy was performed. One hour later the amounts of MMC in the conjunctiva and aqueous were analyzed by reverse-phase high-pressure liquid chromatography. Ciliary bodies were dissected from the enucleated eyes, embedded and investigated by transmission electron microscopy (TEM). Cell height of the nonpigmented ciliary epithelium was morphometrically assessed by means of computer-assisted image analysis.

RESULTS

The light-microscopic analysis of the sectioned cell area revealed reduction of the cell height of the non-pigmented ciliary epithelium (NPCE) after application with soft contact lens (fourfold) and collagen shield (2.5-fold) but not with lyophilisate compared to the untreated eye. The following ultrastructural changes were seen: loss of apical microvilli (CS, CL, LY), disintegrating melanin granules within NPCE (CS), lysis of entire areas with NPCE cells (CS), myelin figures within mitochondria (LY), intracellular vacuoles (CS, CL), lysis of myelinated nerves (CS), myelin figures in mitochondria of endothelial cells (LY), and lysis of stromal fibrocytes (CS). In the control eyes (injection of BSS) none of these ultrastructural changes were detected in the cylindrical NPCE cells. The concentration of mitomycin in the aqueous humor after topical application of MMC on the episclera for 5 min were all below the detection limit (<10 ng/ml). The concentration of MMC in the conjunctiva ranged from 2.1 to 3.7 microg/g.

CONCLUSION

Severe morphologic alterations were seen at the electron-microscopic level after application of MMC 0.2 mg/ml with a collagen shield and with a soft contact lens. They were mildest with lyophilisate and absent in the BSS controls. A new administration device is needed if trabeculectomy is to be performed successfully using MMC in human glaucomatous eyes.

Dry Drops: a new preservative-free drug delivery system

PURPOSE

We compared the tolerability and safety of a lyophilisate (Dry Drops) with conventional eye drops containing the same polymer and electrolytes. In Dry Drops the active ingredient is incorporated in a drop of hydrophilic polymer solution freeze-dried on the tip of a soft hydrophobic carrier strip. Upon contact with tear film and/or conjunctiva the lyophilisate immediately rehydrates and detaches from the carrier.

METHODS

Dry Drops containing HPMC as active ingredient and a preservative-free tear film substitute were applied to 64 eyes of 32 healthy volunteers according to a 22 factorial design in an open-label, cross-over, randomised study. Tolerability and safety were quantified and qualified at 0.5, 2, 5 and 10 min after administration via slit-lamp biomicroscopy, questionnaire and visual analogue scales.

RESULTS

The differences between Dry Drops and conventional eye drops were not statistically significant. The initial sensation of Dry Drops was slightly less uncomfortable than that of the conventional ophthalmic solution. None of the eyes showed any clinical findings with safety implications.

CONCLUSION

The safety and tolerability of a new application form were demonstrated in this phase I study. The improved chemical stability, exact dosing, reduced risk of lesions to the eye surface and good tolerability suggest that the new application device has promise for treatment in ophthalmology as well as in other medical subspecialties.

Unilateral pigmentary degeneration of the retina associated with heterochromia iridis

BACKGROUND

For the past 5 years, a 56-year-old patient has been displaying monocular progressive pigmentary changes in the left eye. Heterochromy of the left eye has been known since childhood. The other eye is clinically and functionally normal. The patient was adopted and he has no children. Therefore, we have no family history.

METHODS

The patient was examined clinically and by means of electroretinography, electrooculography, perimetry, computer tomography, pulsatile ocular blood flow (POBF) measurement, serology and Doppler sonography.

RESULTS

Electrophysiology displayed a considerable reduction of scotopic and photopic ERGs, a reduced dark-through, and a reduced light-rise in the left eye, whereas the fellow eye was normal. The visual field was limited to 5 deg around the fixation point, and a peripheral crescent-shaped arch encircled the temporal-inferior quadrant concomitant to the pigmentary changes. By computer tomography and Doppler sonography a vascular affection was excluded. The left eye displayed lower POBF values. All serological tests were found negative.

CONCLUSION

The clinical picture and negative exclusion criteria indicate a unilateral retinitis pigmentosa. However, with regard to the literature an unequivocal diagnosis can only be made upon hereditary evidence.

Effect of mitomycin C on aqueous humor flow, flare and intraocular pressure in eyes with glaucoma 2 years after trabeculectomy

BACKGROUND

The purpose of this study was to determine the intraocular pressure (IOP), aqueous humor flow, flare and ocular side effects in eyes with a history of hypotony after trabeculectomy with adjunctive mitomycin C (MMC).

METHODS

Thirty-six eyes with primary or secondary open-angle glaucoma and IOP < or = 8 mmHg during the postoperative period were studied 745 +/- 315 days after surgery. MMC (0.2 or 0.5 mg/ml) was applied to the episclera with a cellular sponge. Flare was studied with the Kowa Laser Flare Meter 500. Aqueous humor flow was measured in the afternoon (Fluorotron Master II). IOP, visual fields and best corrected visual acuity were also examined. Twenty-two contralateral eyes without surgical intervention served as controls.

RESULTS

The mean age of patients was 44.5 +/- 16.8 years. The mean IOP was significantly lower in the MMC group than in the control group: 9.6 +/- 6.4 mmHg vs 18.0 +/- 13.6 mmHg at 2 years (P < 0.001). Aqueous flow was significantly lower in subjects treated with MMC than in controls (P < 0.001). The flare values were significantly higher in the MMC-treated group, with a mean of 12.0 +/- 7.7 photon counts/ms, than in the control group, mean 7.9 +/- 4.6 photon counts/ms (P < 0.019).

CONCLUSION

Our data suggest that MMC is a useful ocular hypotensive agent which seems to participate in a change in aqueous humor dynamics when applied topically as an aqueous solution.

Dynamical properties of a ferroelectric capacitor observed through nonlinear time series analysis

By data analysis the ordinary differential equation for the description of an experimental electric resonance circuit with nonlinear capacitor is derived. Triglycine sulfate (TGS) was used as nonlinear dielectric material. This is the most thoroughly investigated ferroelectric with a second order phase transition. Its static dielectric small signal behavior is well described in the framework of the Landau theory, yielding a Duffing-type ordinary differential equation as a model equation of the circuit. Data analysis allows us to check carefully the validity of this model and to determine required corrections of this simplified equation. (c) 1998 American Institute of Physics.

Comparison of two fixed combinations of latanoprost and timolol in open-angle glaucoma

OBJECTIVE

To compare the intraocular pressure (IOP)-reducing effect of the fixed combinations of timolol 0.5% and latanoprost 0.001% or 0.005% after 4 weeks' treatment.

DESIGN

Following a 1-week run-in period on timolol 0.5% once daily, 139 patients were randomized to once-daily treatment with a fixed combination of timolol 0.5% and latanoprost 0.001% (comb. 10) or latanoprost 0.005% (comp. 50) or to the individual monotherapies. The IOP was measured at inclusion and at 8 a.m., noon and 4 p.m. on days 1, 7 and 28.

RESULTS

Comb. 10, comb. 50, latanoprost and timolol reduced IOP by 3.7, 6.1, 4.9 and 2.1 mmHg, respectively, from a baseline mean diurnal IOP (+/- SEM) of 24.8 +/- 0.5, 24.1 +/- 0.4, 25.2 +/- 1.2 and 24.8 +/- 0.9 mmHg, respectively. The difference in IOP reduction was significant between comb. 50 and comb. 10 (P < 0.001), latanoprost (P = 0.046) and timolol (P < 0.001) in favor of comb. 50. There was also a significant difference between latanoprost and timolol (P = 0.007), in favor of latanoprost. All treatments were generally well tolerated.

CONCLUSION

This study indicates that a fixed combination of latanoprost 0.005% and timolol 0.5% could be useful in the treatment of glaucoma.

Dose uniformity of ophthalmic suspensions

PURPOSE

To quantify the rate of redispersion of three commercially available ophthalmic preparations as well as the drug content of single drops during the course of emptying a full container of suspension eyedrops.

SETTING

Department of Ophthalmology, University of Köln, and Department of Pharmaceutical Technology, University of Bonn, Germany.

METHODS

In a computer-controlled test apparatus used to simulate the shaking and dropping behavior of humans under strictly reproducible conditions, we studied the rate of redispersion of three ophthalmic suspensions: 50 mg indomethacin, 50 mg prednisolone-21-acetate, and 50 mg dexamethasone in 5 mL of aqueous fluid. The degree of shaking intensity essential for the redispersion of the ophthalmic suspensions was quantified in healthy persons and patients by an acceleration sensor.

RESULTS

The mean dose delivered and the coefficient of variation of prednisolone were satisfactory. However, only 25% of the dexamethasone was available for administration; the rest remained in the bottle as a cake of sediment. Also, the variability of the drug content between drops was unacceptably high. The mean dose of indomethacin was adequate, but the between-drop variability was excessive.

CONCLUSION

The dose uniformity of suspension eyedrops depends on their homogeneity immediately before administration. Among the formulation factors studied, particle size appears to be the most important. The various redispersion rates of the three drugs underline their clinical profile.

Do standard procedures in squint surgery influence the blood-aqueous barrier?

BACKGROUND AND OBJECTIVE

Surgery on the rectus muscles may interfere with anterior segment perfusion. This study investigates the influence of combined rectus muscle surgery on the blood-aqueous barrier in children. Namely, the influences of tucking and resection procedures were compared.

PATIENTS AND METHODS

Laser flare measurements for tyndallometry were performed preoperatively and postoperatively in 25 children. Fifteen of the children had undergone a combination of a rectus recession and tucking; 10 had undergone a combined recession-resection procedure.

RESULTS

The mean preoperative flare value was 4.1 photon counts/ms versus 3.7 photon counts/ms postoperatively in the eyes that had undergone surgery. Statistical evaluation showed that the postoperative changes were insignificant. No significant difference was found between the two surgical techniques (tucking vs resection) regarding the preoperative versus postoperative flare value change (level of statistical significance .05).

CONCLUSION

Combined squint surgery, either recession-tucking or recession-resection, was not shown to influence the blood-aqueous barrier.

Efficacy of argon laser trabeculoplasty: 3-year preliminary results of a prospective placebo-controlled study

BACKGROUND

It was the purpose of this study to evaluate the efficacy of argon laser trabeculoplasty (ALT) in controlling intraocular pressure (IOP) and avoiding surgical intervention. We also investigated whether topically applied diclofenac sodium eye drops had an influence on the success rate of ALT compared with placebo eye drops.

METHODS

The indication for ALT was progressive glaucoma uncontrolled by maximal tolerated medical therapy. Thirty-nine of 41 patients were available for follow-up after 1122 +/- 239 days.

RESULTS

Twenty-one of 39 eyes failed during the first 3 years of follow-up for one or more reasons: 11 eyes required additional laser treatment and/or filtration surgery because of progressive visual field loss or unacceptably high IOP, 9 eyes failed to have a final IOP > or = 21 mmHg, and 7 eyes failed because of an increase in the number of the medications. This yields a success rate for ALT of 46% for 3-year follow-up. There was no significant difference between diclofenac sodium- and placebo-treated eyes concerning the success rate after 3 years (P > 0.05).

CONCLUSION

We conclude that the use of ALT for the treatment of glaucoma is best reserved for cases in which medical avenues of treatment have been exhausted.

Clinical dose-regimen studies with latanoprost, a new ocular hypotensive PGF2 alpha analogue

This review summarizes recent short-term clinical studies evaluating the ocular hypotensive efficacy of different dose-regimens of latanoprost. When tested in ocular hypertensive and glaucoma patients concomitantly treated with timolol, 0.006% latanoprost given only in the evening, was found to be more effective than the same concentration given in the morning and evening. In patients with open angle, pseudoexfoliation and normal tension glaucoma not receiving other treatment, once-daily 0.005% latanoprost monotherapy was more effective than twice-daily 0.0015% latanoprost treatment. No significant differences were found in conjunctival hyperemia, sensory irritation or blood-aqueous barrier permeability between these two treatment regimens. Although the ocular hypotensive efficacy of once-daily application of the lower concentration (0.0015%) latanoprost was not investigated, we would conclude, based on the studies reviewed here, that at a concentration of 0.005%, once-a-day dosing of latanoprost is highly effective in significantly reducing intraocular pressure, causing only minimal, clinically acceptable short-term ocular side effects.

The effect of latanoprost 0.005% once daily versus 0.0015% twice daily on intraocular pressure and aqueous humour protein concentration in glaucoma patients. A randomized, double-masked comparison with timolol 0.5%

BACKGROUND

Latanoprost is a PGF2 alpha analogue which reduces the intraocular pressure (IOP) by increasing the uveoscleral outflow. The objective of this study was to investigate the effect of two different regimens of latanoprost on the diurnal IOP and also the effect of latanoprost on the blood-aqueous barrier measured with a laser flare cell meter (Kowa FM-500). Moreover, the safety aspects of the two regimens regarding hyperemia were studied.

METHODS

A double-masked, randomized study was performed in 30 patients (9 males, 21 females; mean age 61.9 years) with primary open-angle glaucoma or pseudoexfoliation glaucoma. Twenty patients were treated with latanoprost 0.0015% twice daily or 0.005% once daily for 3 weeks in a cross-over design. Ten patients received timolol 0.5% twice daily as control.

RESULTS

Latanoprost 0.005% once daily reduced IOP (+/- SEM) more effectively than latanoprost 0.0015% twice daily (9.8 +/- 0.9 mm Hg and 6.7 +/- 0.9 mm Hg, respectively). There was a statistically significant increase in the aqueous humour protein concentration within the timolol group (P = 0.004), but not within the latanoprost group (P = 0.97). There was no statistically significant difference in the change in aqueous humour protein concentration from baseline between latanoprost and timolol groups (P = 0.08). No statistically significant difference in conjunctival hyperemia between the two latanoprost regimens was found (P = 0.37).

CONCLUSION

Latanoprost 0.005% once daily reduced IOP more effectively than latanoprost 0.0015% twice daily (P < 0.001). Latanoprost had no statistically or clinically significant effect on the blood-aqueous barrier. There was no difference in hyperemia between the two regimens. Both concentrations of latanoprost reduced IOP at least as well as timolol 0.5% eye drops.

[Laser flare measurement with 3 different nonsteroidal anti-inflammatory drugs after phacoemulsification with posterior chamber lens implantation]

In a prospective, randomised, double-masked, parallel-group study we compared the antiinflammatory effect of diclofenac sodium 0.1%, flurbiprofen 0.03%, and indomethacin 1.0% ophthalmic suspension in 99 patients undergoing phacoemulsification and posterior chamber lens implantation. The reduction in anterior chamber flare from day 1, as measured with the laser flare-meter (FM-500, KOWA) on day 4-5 postoperatively was significantly greater in the diclofenac group than with flurbiprofen (p = 0.022). Patients treated with diclofenac had significantly less burning and stinging than patients on flurbiprofen and indomethacin on postoperative days 4-5 (p < 0.0001) and 12-14 (p = 0.001). Diclofenac sodium appears to be more potent than flurbiprofen in controlling intraocular inflammation after cataract surgery, while having better local tolerance than flurbiprofen or indomethacin.

Effect of 3.0 mm tunnel and 6.0 mm corneoscleral incisions on the blood-aqueous barrier

PURPOSE

To study of the effect of silicone intraocular lens (IOL) implantation using a 3.0 mm tunnel incision with that of implantation though a 6.0 mm corneoscleral incision after phacoemulsification in human eyes.

SETTING

Department of Ophthalmology, University of Köln, Germany.

METHODS

In a prospective, randomized clinical study, 50 patients with senile cataract had phacoemulsification and IOL implantation through a 3.0 mm tunnel or a 6.0 mm corneoscleral incision. To assess blood-aqueous barrier (BAB) disruption, preoperative and postoperative sodium fluorescein concentrations in the anterior chamber were measured with the Fluorotron Master II. Diclofenac sodium 0.1% was applied to the operative eyes five times a day for 5 days. The contralateral eyes served as controls.

RESULTS

There was no significant between-group difference in sodium fluorescein concentrations in the 5 days after surgery.

CONCLUSION

The findings underline our clinical impression that BAB disruption 5 days after surgery does not differ significantly with the type and length of scleral incision used for IOL implantation.

The influence of strabismus surgery on the blood-aqueous barrier: tyndallometry case studies in patients with risk factors

We present tyndallometry as a method for investigation of subclinical changes in anterior-chamber flare in patients with risk factors regarding anterior-segment ischemia after squint surgery. The cases of six adult patients who underwent surgery on the vertical recti and who had additional risk either because of dysthyroid orbitopathy or because of transpositions carried out on the recti are presented. In one case a transient subclinical increase in the flare value was observed. This noninvasive method seems suitable for the provision of further information on the pathophysiology of anterior-segment ischemia and for monitoring of patients at special risk postoperatively such that early treatment can be started if necessary. Additionally, early detection of nonischemic intraocular inflammation in the postoperative course is rendered possible by this examination.

A new transdermal delivery system for pilocarpine in glaucoma treatment

We studied the intraocular pressure (IOP)-lowering effect and the side effects of a new transdermal delivery system (TDS) containing pilocarpine. After giving their written informed consent, patients were randomly assigned to receive a pilocarpine TDS or a placebo TDS. Two patches, each containing 30 mg of pilocarpine or placebo, were applied to the supraclavicular skin of 24 patients. The IOP was recorded before and at +12, 16, and 20 h after application. Plasma samples were analyzed for pilocarpine before treatment and 12 and 20 h later via high-performance liquid chromatography. The amount of drug remaining on the dermal patches was analyzed at 20 h. The mean IOP recorded before application was 22.7 +/- 5.8 mmHg. As compared with the placebo TDS, the pilocarpine TDS did not significantly reduce IOP at 12, 16, or 20 h after application (P = 0.42). The mean plasma concentrations were 2.9 ng/ml at 12 h and 1.3 ng/ml at 20 h. The verum TDS showed a residual mean drug concentration of 35.3 mg pilocarpine on the TDS. A substantial amount of pilocarpine was released from the TDS to the dermis, causing detectable plasma levels of pilocarpine at 12 and 20 h after administration. The pilocarpine TDS is a new nonocular pharmaceutical device that should avoid the side effects well known in glaucoma treatment when conventional eye drops are used.

[Disorder of the blood-aqueous barrier after eye muscle operation in children]

We wanted to study the effect of squint surgery on the blood-aqueous barrier in children. Our interest was to ascertain whether or not there is a breakdown of the blood-aqueous barrier after routine squint surgery, and whether this would need antiinflammatory treatment with steroids.

PATIENTS AND METHODS

Forty-seven eyes of 18 girls and 7 boys (age range 4-14 years) were examined. The children were generally healthy and had not undergone any previous eye surgery. The mean age of patients (n = 25) was 7.8 +/- 3.1 years. Using the laser flare meter Kowa FM-500, the flare (photocounts/ms) in the anterior chamber was measured before and on the 2nd day after squint surgery (n = 32). Fifteen eyes served as controls and were not operated on. Following surgery, the operated eyes were treated with aminoglycoside eye drops (three times daily). No steroids or non-steroidal antiinflammatory drugs were applied before or after surgery.

RESULTS

The flare values were 4.10 +/- 1.29 photocounts/ms before and 3.89 +/- 1.27 photocounts/ms after squint surgery. There was no significant increase (P = 0.58) of flare on the 2nd postoperative day.

CONCLUSION

Our data confirm that there is no clinically significant disruption of the blood-aqueous barrier following squint surgery. We therefore conclude that there is no need for postoperative therapy with steroids.

[Dosage problems in suspension eyedrops]

PURPOSE

In opthalmic suspensions, the mean dose and the uniformity of amounts administered in single drops depend upon the redispersibility of drug particles by shaking. The present article is a contribution to the development of the experimental and theoretical basis for a reproducible test, by which the dose uniformity of suspension eyedrops can be assessed under therapeutically relevant conditions. The requirement that suspension eyedrops and similar dosage forms should be redispersable after sedimentation upon storage is stated in the monographs on eyedrops of the German Pharmacopoeia and can be found in similar contexts in other pharmacopoeias. Until now, however, no corresponding test method has been specified.

METHODS

Shaking profiles were recorded in 31 subjects and 27 patients using an acceleration sensor. They were compared with the acceleration profile of a computer-controlled pneumatic shaker and sampler. Both frequency and intensity of the shaking action were quantified by Fourier analysis of the acceleration profiles. The drug content of single drops of Isopto-dex (0.1% dexamethasone), Chibro-Amuno 3 (1% indomethacin), and Inflanefran-forte (1% prednisolone acetate) was assessed exhaustively in four 5-ml specimens of each ophthalmic suspension using the apparatus. The dose uniformity of single drops of suspension eyedrops was measured by UV-spectrophotometry for the entire contents of bottles. Four samples per day were drawn after six shaking cycles for approximately 4 weeks with three intervals of 4 h during daytime and 1 interval of 12 h during the night.

RESULTS

The shaking intensity of patients was lower than that of healthy subjects, while the frequency was similar for both groups. The intensity of the apparatus corresponds to the 67th percentile of the patients and to the 18th percentile of the healthy subjects. It was sufficiently close to the central values of both distributions to allow comparisons. for Isopto-dex, the mean drug content of 9.5 microns per drop amounted to only 25% of the value expected after complete redispersion, with a coefficient of variation (CV) of 23%. The mean value for Chibro-Amuno 3 was 93% of the expected quantity of indomethacin with a CV of 34%, while the mean content of Inflanefran-forte drops was 95% of the labelled dose with a CV as low as 9%.

CONCLUSION

The drug content of single drops of ophthalmic suspensions can be studied under well-defined and reproducible conditions by means of a computer-controlled pneumatic shaking and sampling apparatus. Under the conditions prevailing in this study, the solidified sediment of Isopto-dex was incompletely redispersed, so that doses were significantly too low. A variable dosing pattern with acceptable mean was observed for Chibro-Amuno 3, while the results for Inflanefran-forte were fully satisfactory.

Histopathology of episcleral fibrosis after trabeculectomy with and without mitomycin C

BACKGROUND

The aim of the study was to investigate the histopathologic features of scar tissue which have proliferated at the site of trabeculectomy of surgical failures after procedures with and without the use of the antimetabolite mitomycin C (MMC).

METHODS

We obtained seven surgical specimens after trabeculectomy without MMC and five specimens after trabeculectomy with MMC, which were compared with 23 controls. Sections were stained with hematoxylin and eosin, Verhoeff-van Gieson, Grocott methenamine silver, and alcian blue. An immunohistochemical stain was performed for alpha-smooth muscle actin.

RESULTS

Specimens from eyes operated without MMC showed dense scar tissue with many fibroblasts, much ground substance, parallel-oriented collagen fibers, and contractile intracellular proteins within the fibroblasts. Specimens from eyes operated with MMC consisted of tissue with only few fibroblasts which did not exhibit contractile proteins. Collagen fibers were arranged randomly with less ground substance.

CONCLUSION

Even after 1-10 months, the scar tissue was distinctly different in the two groups. These results suggest that the use of MMC has long-term effects in vivo. Surgical failures related to scar formation are possible and not reduced to zero.