Effects of the combination of bimatoprost and latanoprost on intraocular pressure in primary open angle glaucoma: a randomised clinical trial

AIMS

To evaluate the effect of the combination of bimatoprost and latanoprost on intraocular pressure (IOP) in primary open angle glaucoma (POAG).

METHODS

An open label randomised clinical trial was conducted, which included 18 glaucomatous patients (36 eyes). In the first 4 weeks, latanoprost 0.005% was prescribed for both eyes of the patients and any other antiglaucoma medication was discontinued. In the next 4 weeks (phase 1), bimatoprost 0.03% was combined with latanoprost in one randomly assigned eye (case eye) of each patient. In the next 4 weeks (phase 2), bimatoprost was discontinued in the case eyes, while bimatoprost was substituted for latanoprost in the fellow eye (control eye). The IOP was measured at the end of the first 4 weeks (baseline measurement) and weekly during phases 1 and 2.

RESULTS

In the case eyes, the mean IOP increased along the first phase (1.8 mm Hg; p = 0.006) when compared to baseline measurements. The IOP returned to previous values after discontinuation of bimatoprost in phase 2. In the control eyes, the mean IOP did not change throughout the study.

CONCLUSION

The combination of bimatoprost and latanoprost in POAG increases the IOP and should not be considered as a therapeutic option.

Influence of keratometric readings on comparative intraocular pressure measurements with Goldmann, Tono-Pen, and noncontact tonometers

PURPOSE

To evaluate the influence of keratometric measurements on the concordance of intraocular pressure (IOP) readings with three applanation tonometers.

PATIENTS AND METHODS

The IOPs of 404 eyes of 202 patients from a general eye clinic were measured by Goldmann, Tono-Pen XL, and noncontact Nidek NT 2000 tonometers. Differences in the IOP measurements between Goldmann and the other two tonometers (deltaIOPG-TP and deltaIOPG-NCT) were analyzed in the overall group and within three subgroups based on keratometry measures: flatter, intermediate, and steeper corneas (quartiles as cut-off points). Regression analysis of deltaIOP and keratometry measures was also performed. Right and left eyes were analyzed separately.

RESULTS

The IOP readings taken with the Goldmann tonometer were significantly higher than those taken with either of the other two tonometers within the overall study population. The deltaIOP within the three keratometric subgroups was not statistically significant except for deltaIOPG-TP in the right eyes. Regression analysis showed that keratometry and deltaIOPG-TP and deltaIOPG-NCT had a significant but very weak coefficient of correlation in the right eye, but not in the left.

CONCLUSION

Corneal curvature within the normal range does not have a clinically significant influence on the concordance of IOP readings obtained with Goldmann and Tono-Pen or noncontact tonometers.

[The pupil in the chronic phase of Chagas disease and the reaction to pilocarpine and phenylephrine]

To develop a method to analyse pupillary disturbances in patients with chronic Chagas disease in an endemic area, ten chagasic and ten normal subjects were matched according to sex, age and race. Pupillary diameter and area were determined using projection and topography techniques and compared between groups. Both pupils were visualised simultaneously. In each case three photographs were taken under standardised illumination. The first photo was obtained without medication, the second, 30 minutes after instillation of 0,1% pilocarpine and the last 30 minutes after instillation of 3% phenylephrine (60 minutes after pilocarpine). Pupils of chagasic patients had a statistically significant greater initial diameter and area, irregularity of the pupil border, greater percentual reduction in diameter and area after pilocarpine 0.1% and greater percentual increase in diameter and area after 3% phenylephrine eyedrops. The method developed for this study was considered satisfactory. The results suggest ocular autonomic nervous system disturbances in chagasic patients.

Aqueous humor dynamics in rats

BACKGROUND

In order to determine normal outflow facility and aqueous humor production values in Lewis rats, we established methods of measuring aqueous humor dynamics in this animal.

METHODS

Outflow facility was determined using anterior chamber infusion with constant pressure. Aqueous humor production was determined by a technique of dilution with FITC-albumin.

RESULTS

The mean outflow facility was 0.044 +/- 0.01 microliter/min/mmHg. Rats weighing less than 300 g had lower values than did rats weighing more than 300 g (0.034 +/- 0.006 microliter/min/mmHg vs 0.050 +/- 0.015 microliter/min/mmHg, P = 0.009). The mean aqueous humor production was 0.350 +/- 0.110 microliter/min. The turnover rate of aqueous humor production per minute was 2.23%.

CONCLUSIONS

Anterior chamber infusion with constant pressure and the FITC-albumin method allow measurement of the outflow facility and aqueous humor production in Lewis rats. These methods may be useful in assessing aqueous humor dynamics when rats are used as a glaucoma model.

Cataract surgery after trabeculectomy

BACKGROUND AND OBJECTIVE

To determine the effect of cataract surgery on glaucomatous eyes with good intraocular pressure (IOP) control after trabeculectomy.

PATIENTS AND METHODS

Twenty-two eyes with functional blebs that underwent cataract extraction were retrospectively analyzed.

RESULTS

The mean (+/- SD) preoperative IOP was 11.0 +/- 4.3 mm Hg. The mean (+/- SD) postoperative IOPs at 1, 2, 6, and 9 months were 15.5 +/- 4.9, 12.6 +/- 4.7, 14.6 +/- 5.6, and 19.0 +/- 7.9 mm Hg, respectively. At each interval except for the second month, the mean IOP was statistically significantly higher than the preoperative value (P = .0003, .24, .02, and .0009, respectively). The total number of medications was also higher (3 preoperatively versus 27 postoperatively). The interval between the two surgeries had no influence on IOP control. Intraoperative complications during cataract surgery, particularly vitreous loss, were associated with poor IOP control. Phacoemulsification had less of an effect on the postoperative IOP control than did extracapsular cataract extraction.

CONCLUSIONS

Eyes with previous successful trabeculectomies had higher IOPs and required more medications after subsequent cataract surgeries.

Effects of intraoperative mitomycin-C on the function of Baerveldt glaucoma drainage implants in rabbits

PURPOSE

The purpose of this study was to assess the effects of intraoperative mitomycin-C (MMC) on the function of Baerveldt glaucoma implants in rabbits.

METHODS

Bilateral implantations of 200 mm2 Baerveldt drainage devices were performed in 30 normal albino rabbits. One eye, randomly selected, received intraoperative application of MMC at the site of the implant plate for 5 min, via a 6 x 4 x 2 mm cellulose sponge saturated with 0.5 mg/ml of MMC. The opposite eye served as a control. MMC-treated and control eyes (five animals each group) were compared for intraocular pressure (IOP), resistance to flow, flow rates through the implant and histopathological findings at 2, 4, 6, 12, and 24 weeks postoperatively. Resistance to flow and flow rates through the implants were studied after opening the cornea and connecting the drain tube to a micromanometric system.

RESULTS

Preoperative IOP did not differ between groups. MMC-treated eyes had lower levels of IOP than did controls at all postoperative times. The differences in IOP were statistically significant up to 8 weeks postoperatively. Resistance to flow was lower in MMC-treated eyes at all times studied, but the differences were statistically significant only at the time points of 2, 4, and 6 weeks. Flow rates through the implant bleb were always higher in MMC-treated eyes, and statistically significant differences were seen at 2, 4, 6, and 24 weeks. Histopathologically, MMC-treated eyes had thinner implant capsules with delayed maturation and less inflammatory infiltrate.

CONCLUSION

MMC causes lower IOP and higher perfusion rates through the implant capsule at 2, 4, and 6 weeks postoperatively. Wound dehiscence, bleb leaks, and extraocular muscle injury were observed only in MMC-treated eyes.

Visual recovery after trabeculectomy

PURPOSE

We retrospectively analyzed 155 eyes of 155 patients who underwent trabeculectomy with and without antimetabolites to determine the time for recovery of visual acuity postoperatively and to determine factors associated with delayed recovery of visual acuity and visual loss.

METHODS

Factors examined included age, race, preoperative visual field grading. Humphrey Field Analyzer's indices (mean deviation and corrected pattern standard deviation), optic nerve cup-to-disk ratio, antimetabolite use, postoperative complications, and postoperative hypotony. The mean age of the patient was 63.6 +/- 15.7 years. Mean follow-up was 14.4 +/- 8.5 months (range 6-30).

RESULTS

One hundred forty-four patients (93%) regained their preoperative visual acuity, and 11 patients (7%) sustained visual loss. For the 144 patients who regained visual acuity, recovery time ranged between 1 and 244 days (median 6); recovery occurred before the second month in 128 patients (89%) and was delayed beyond 2 months in 16 patients (11%). Among the 60 primary open-angle glaucoma patients with preoperative visual acuity better than 20/200, those with delayed visual recovery had significantly worse preoperative visual field grades than did those with early recovery (p = 0.04). The preoperative Humphrey mean deviation was also higher (16.3 dB vs. 11.2 dB, p = 0.04). All 16 patients with delayed visual recovery also had postoperative hypotony (p = 0.01); this was transient (<2 weeks) in 12 patients and prolonged in four. In patients who failed to regain visual acuity, the visual loss did not correlate with any preoperative risk factors or hypotony, but these patients did have a higher incidence of postoperative complications (p = 0.05).

CONCLUSION

We conclude that patients with primary open-angle glaucoma who have advanced visual field defects are at greater risk of delayed visual recovery after trabeculectomy and that postoperative hypotony contributes to this delay.

Surface area of glaucoma implants and perfusion flow rates in rabbit eyes

PURPOSE

These experiments were designed to analyze the relationship between glaucoma drainage implant surface area and the physiological function of the surrounding encapsulation.

METHODS

Three sizes of Baerveldt implants were studied. Commercially available 200 mm devices were trimmed to reduce surface area to 100 and 50 mm (one side), respectively. Five samples of each size of device were studied 3 weeks after implantation in normal rabbit eyes by perfusing the drain tubes in vivo using a micromanometric system allowing precise control of flow rates. Additional eyes were analyzed at 12 weeks. Resistance to flow was calculated using Poiseuille's equation after at least three different flow rate readings for each implant, and a linear regression line was plotted for each eye. Flow rates at the pressures of 10, 15, 20, and 25 mm Hg were standardized by slope calculation and mean flow rate values for each size of implant compared statistically. Calculated flow per unit area (hydraulic conductivity) was calculated for each sized implant.

RESULTS

The perfusion flow tests demonstrated statistically significant differences for the values of resistance to flow and flow through the implants for the three surface areas tested. The 200 mm implants had higher flow rates and lower resistance values. A statistically significant inverse correlation was found between the surface area of the implant and the resistance to flow (p = 0.0002). A statistically significant direct correlation was also found between the surface area of the implant and the values of flow rates (p = 0.0002) through the capsules. Hydraulic conductivity of the capsules was virtually identical for all three sizes of implants tested.

CONCLUSION

The results demonstrate a direct relationship between the surface area of glaucoma implants and the filtering capacity of their surrounding capsules.

In vitro and in vivo flow characteristics of glaucoma drainage implants

PURPOSE

To determine pressure-flow characteristics at physiologic flow rates in vitro and in vivo in rabbits for Ahmed, Baerveldt, Krupin disk, and OptiMed glaucoma implants. The Molteno dual-chamber implant also was evaluated in vivo only.

METHODS

Five samples of each glaucoma implant were studied. Baerveldt implants were ligated partially for in vitro testing. Opening and closing pressures in air or after immersion in balanced salt solution or plasma were evaluated for the valved devices (Ahmed and Krupin). Pressures were measured in vitro and in vivo in normal rabbits at flow rates preset at between 2 and 25 microliters/minute after the tubes were connected to a closed manometric system. In vivo measurements were made 24 hours after implantation. Resistance to flow was calculated using Poiseuille's equation after at least three separate flow rate readings.

RESULTS

In air, the Ahmed and Krupin valves had opening pressures of 9.2 +/- 3.4 and 7.2 +/- 0.6 mmHg and closing pressures of 5.2 +/- 0.9 and 3.9 +/- 1 mmHg, respectively. Neither opening nor closing pressures could be determined when Ahmed and Krupin valves were immersed. In vitro, the Ahmed and OptiMed devices had higher pressures than did other devices at a 2-microliters/minute flow rate of balanced salt solution. During perfusion with plasma, only the OptiMed device maintained higher pressures than with balanced salt. With all devices, pressures fell rapidly to zero after flow was stopped. The OptiMed device demonstrated the highest resistance values. In vivo, the Ahmed device provided pressures of 7.5 +/- 0.8 mmHg and the OptiMed device gave pressures of 19.6 +/- 5.6 mmHg at a 2-microliters/minute flow rate. After 15 minutes of flow shutdown, the OptiMed implant maintained pressures of 7.1 +/- 1.1 mmHg. The Baerveldt (nonligatured), Krupin, and Molteno dual-chamber implants had similar resistances and pressures in vivo. Pressures with all devices in vivo fell rapidly to zero after conjunctival wound disruption.

CONCLUSION

Neither the Ahmed nor Krupin devices had demonstrable opening or closing pressures when tested in vitro immersed in balanced salt solution or plasma. With all devices, pressures were higher in vivo than in vitro due to tissue-induced resistance around the explant. Both Ahmed and Krupin valves functioned as flow-restricting devices at the flow rates studied, but did not close after initial perfusion with fluid.

Hypotony following trabeculectomy

OBJECTIVE

To determine the risk factors for development of postoperative hypotony and the effects of hypotony on the outcome of surgery in terms of intraocular pressure (IOP) control and final visual acuity in patients who underwent standard trabeculectomy, trabeculectomy with postoperative 5-fluorouracil injections, trabeculectomy with intraoperative mitomycin-C, or trabeculectomy with both antimetabolites.

PATIENTS AND DESIGN

We retrospectively reviewed the outcome in 155 eyes of 155 patients who underwent standard trabeculectomy (n = 15), trabeculectomy with postoperative 5-fluorouracil injections (n = 81), trabeculectomy with intraoperative mitomycin-C (n = 55), or trabeculectomy with both antimetabolites (n = 4).

RESULTS

Hypotony developed in 108 (69.6%) eyes (IOP < 6 mm Hg) at some point postoperatively; this was transient (< 14 days) in 75 eyes, and prolonged (> 14 days) in 33 eyes. The positive preoperative factors for the development of prolonged hypotony were young age, myopia, and preoperative use of carbonic anhydrase inhibitor. The mean age of patients in whom prolonged hypotony developed was 57.3 +/- 18.3 years (compare the mean age without prolonged hypotony, 65.3 +/- 14.5 years, p = 0.02). Sixteen of 33 (48%) patients in whom prolonged hypotony developed were myopic (p = 0.02), and 23 of 33 (70%) patients in whom prolonged hypotony developed used preoperative carbonic anhydrase inhibitor (p = 0.07).

CONCLUSIONS

There was no difference in the incidence of hypotony between patients who received 5-fluorouracil and those who received mitomycin-C. Postoperative hypotony was associated with three types of postoperative complications: shallow anterior chamber, choroidal detachment, and hypotony maculopathy (p = 0.02, 0.000, and 0.05, respectively). Hypotony did not have any effect on the success of surgery in terms of IOP control, but did have an effect on the visual outcome. Fourteen of the 33 patients (42.4%) in whom prolonged hypotony developed had worse visual acuity (p = 0.002); of these cases, four were due to hypotony maculopathy.

[Anisocoria in the chronic phase of Chagas' disease]

To compare the frequency of anisocoria in patients with chronic Chagas' disease a prospective double-blind study was done in 131 patients with positive serology for Chagas' disease and 138 negative, at Mambaí (GO-Brazil), which is an endemic area for Chagas' disease. To detect anisocoria, pupillometry was done with a millimetric ruler. Anisocoria was seen in 10(7.6%) patients with Chagas' disease and in 3(2.1%) normal subjects. The chi-square test showed statistical significance at level of 5%. Chagas' disease must be included among the causes of anisocoria.

Effects of external irrigation on mitomycin-C concentration in rabbit aqueous and vitreous humor

PURPOSE

These experiments were performed to determine what effect external irrigation with balanced salt has on limiting penetration of mitomycin-C into the aqueous and vitreous.

METHODS

Bilateral 5 min scleral applications of mitomycin-C (0.5 mg/ml) were performed in 21 rabbits using identical 6x4x1 mm cellulose sponges uniformly soaked with 0.2 ml of the mitomycin-C solution. Irrigation of one eye, randomly selected, was then carried out with 10 ml of balanced salt solution over 1 min. High performance liquid chromatography was used to analyse aqueous and vitreous samples obtained from separate animals at 5, 15, 30, and 60 min and at 2,4, and 6 h after sponge removal.

RESULTS

Nonirrigated eyes demonstrated continual rise in aqueous mitomycin-C concentration over 1 h. Irrigated eyes demonstrated lower mitomycin-C concentrations at all times studied and a continual fall in aqueous concentration after 15 min. Vitreous mitomycin-C was detected in both groups only at 5 min.

CONCLUSIONS

Irrigation with balanced salt substantially reduces intraocular diffusion of mitomycin-C.

Postoperative complications and short-term outcome after 5-Fluorouracil or mitomycin-C trabeculectomy

PURPOSE

This study was performed to compare the postoperative complications between trabeculectomy with 5-fluorouracil injected after surgery and trabeculectomy with mitomycin-C applied intraoperatively.

METHODS

Retrospective review was done on 77 eyes that had received 5-fluorouracil injections after trabeculectomy, 45 eyes that received mitomycin-C during trabeculectomy, 4 eyes that received both agents, and 15 eyes that received neither agent between January 1991 and July 1992. 5-fluorouracil-treated eyes received a mean of 5 +/- 2.5 subconjunctival injections of 5 mg each (5 mg/0.1 ml). Mitomycin-C-treated eyes received 3-5 min exposure to 0.5 mg/ml mitomycin-C. Several parameters were compared between groups including hypotony defined as intraocular pressure <6 mm Hg. Success was defined as IOP <21 mm Hg with or without medications. Followup averaged 6-12 months.

RESULTS

Complications including hypotony, loss of visual acuity, choroidal effusion, shallow anterior chamber, cataract progression, hyphema and procedure failure were equivalent between 5-fluorouracil and mitomycin-C-treated groups.

CONCLUSIONS

Excluding corneal epithelial toxicity that was more common with 5-fluorouracil, the two agents used had similar success and complications during the short followup period.

Trabeculectomy with mitomycin C in glaucoma associated with uveitis

Twenty-four trabeculectomies performed in 24 patients for control of uveitic glaucoma were retrospectively evaluated to analyze the effect of intraoperative application of mitomycin C (MMC) on the short-term outcome of trabeculectomy for glaucoma associated with uveitis. Success rates, postoperative levels of intraocular pressure (IOP), and complications were studied. After a mean follow up of 9.87 months (range, 3 to 27 months), 18 eyes (75%) achieved an IOP of 21 mm Hg or less without antiglaucoma medications. The same IOP level with one antiglaucoma medication was achieved in four eyes (16.6%). Statistical analysis demonstrated a significant reduction in IOP postoperatively during the period studied (P = .0001). Complications observed included exacerbation of the uveitis (12.5%), choroidal detachment (12.5%), hypotony (8.3%), postoperative shallow anterior chamber (4.2%), wound leak (4.2%), hyphema (4.2%), and macular edema (4.2%). The results of this retrospective and uncontrolled study suggest that intraoperative application of MMC may be a good option for enhancement of short-term trabeculectomy success rates in cases of uveitic glaucoma.

Site of mitomycin-C application during trabeculectomy

The outcome and postoperative complications after trabeculectomies with mitomycin-C application before flap dissection (episcleral) or after flap dissection (scleral bed) were analyzed retrospectively in 82 patients (82 eyes). Thirty-six eyes (43.9%) had an episcleral mitomycin-C application, and 46 (56.1%) had scleral-bed mitomycin-C administration. After a mean follow-up of 10.1 +/- 3.8 months and 9.9 +/- 4.3 months for the episcleral and scleral-bed groups, respectively, complete success (intraocular pressure </=21 mm Hg without medications) was achieved in 18 eyes (50%) in the episcleral group and in 43 eyes (93.5%) in the scleral-bed group. Qualified success (intraocular pressure </=21 mm Hg with glaucoma medications) was achieved in 10 eyes (27.8%) in the episcleral group and in 8 eyes (17.4%) in the scleral-bed group. Rates of cumulative survival and time of trabeculectomy survival were statistically higher in the scleral bed group (p = 0.002 and 0.0004, respectively). There was a statistically significant difference in the success rates between groups (p = 0.03). The final intraocular pressure was significantly lower in the scleral-bed group (p = 0.015). There were no differences in duration of postoperative follow-up or frequency of complications. Mitomycin-C application after the scleral flap dissection appears to be associated with higher success rates than mitomycin-C application before scleral flap dissection.

Mitomycin-C concentration in human aqueous humour following trabeculectomy

The aim of the study was to determine mitomycin-C (MMC) concentrations in human aqueous humour during trabeculectomy and to correlate anterior chamber concentrations with method of application. MMC was applied intra-operatively by saturating sponges, ranging in size from 2 x 2 x 5 mm to 2 x 4 x 10 mm on dry cut, with 0.5 mg/ml MMC during trabeculectomy for 3-5 minutes. Applications to episclera were made in 18 cases and to the scleral bed after scleral flap dissection in 9 cases. Aqueous samples were collected by paracentesis with a 30 gauge needle 2-7 minutes after removal of sponge and external irrigation. Aqueous MMC concentrations were determined by high-performance liquid chromatography. Aqueous MMC concentration in 27 samples ranged from below minimum detectable concentration (less than 5 ng/ml) to 120.8 ng/ml. Mean aqueous drug levels obtained when the applications were to the scleral bed were 35.65 +/- 39.17 ng/ml (range 5-120.8 ng/ml). Applications on episclera gave mean aqueous concentrations of 4.98 +/- 9.11 ng/ml (range 0-33.3 ng/ml). The difference was statistically significant (p = 0.004). There were no correlations between sponge size, time of MMC exposure and aqueous MMC level. In conclusion, MMC is detectable in aqueous humour within minutes of external application and the aqueous concentration level is higher if the application is in the scleral bed than on the episclera. Toxicity of the drug at this concentration range for corneal endothelial cells needs further investigation via in vitro and clinical studies.

Pseudo-Brown's syndrome as a complication of glaucoma drainage implant surgery

Two cases of pseudo-Brown's syndrome occurring after superior nasal implantation of glaucoma filtering devices are described. We hypothesize that this restriction in ocular motility was due to the mechanical effects of large filtering blebs or increased inflammation and scar formation in the superior nasal quadrant. Serial ultrasound examinations of our patients demonstrated development of a large bleb, coincidental with the disturbance in motility. Because of the risk of strabismus, we no longer recommend placing large implant devices in the superior nasal quadrant in eyes that have good vision.