Neil T. Choplin

A six-month randomized clinical trial comparing the intraocular pressure-lowering efficacy of bimatoprost and latanoprost in patients with ocular hypertension or glaucoma

Abstract Purpose To compare the intraocular pressure (IOP)-lowering efficacy and safety of topical bimatoprost 0.03% with latanoprost 0.005%. Design Multicenter, randomized, investigator-masked clinical trial. Methods After washout of glaucoma medications, ocular hypertension or glaucoma patients were randomly assigned to once-daily bimatoprost 0.03% (n = 133) or latanoprost 0.005% (n = 136) for 6 months. The primary outcome measure was mean change from baseline IOP (8 am, 12 pm, 4 pm). Secondary measures included mean IOP, ophthalmologic examination, adverse events, and the percentage of patients reaching specific target IOPs. Results Mean change from baseline IOP was significantly greater for bimatoprost patients than for latanoprost patients at all measurements on each study visit; 1.5 mm Hg greater at 8 am ( P P P = .004) at month 6. At the end of the study, the percentage of patients achieving a ≥20% IOP decrease was 69% to 82% with bimatoprost and 50% to 62% with latanoprost ( P ≤ .003). In addition, the distribution of patients achieving target pressures in each range (≤13 to ≤ 15 mm Hg, >15 to ≤ 18 mm Hg, and > 18 mm Hg) showed that bimatoprost produced lower target pressures compared with latanoprost at all times measured ( P ≤ .026). Few patients were discontinued for adverse events (6 on bimatoprost; 5 on latanoprost). On ophthalmologic examination, conjunctival hyperemia ( P P = .064) were more common in bimatoprost patients. Conclusions Bimatoprost is more effective than latanoprost in lowering IOP. Both drugs were well tolerated, with few discontinuations for adverse events.

Initial Clinical Experience With the Ahmed Glaucoma Valve Implant

PURPOSE We studied the Ahmed Glaucoma Valve implant, an aqueous shunting device that has a unidirectional valve mechanism designed to prevent postoperative hypotony in eyes with intractable glaucoma. METHODS In this multicenter, prospective clinical trial, we studied 60 eyes (60 patients) with increased intraocular pressure or glaucoma that had not responded to medical treatment, laser photocoagulation, or previous glaucoma surgery, in which the Ahmed Glaucoma Valve implant was placed to decrease intraocular pressure. RESULTS Success was defined as intraocular pressure less than 22 mm Hg and greater than 4 mm Hg for two months or longer, intraocular pressure that was lowered by at least 20% from preoperative values (in eyes with preoperative intraocular pressures less than 22 mm Hg), and no additional glaucoma surgery or visually devastating complications. Cumulative probability of success at 12 months was 78%. Eight (13%) of 60 eyes had intraocular pressure less than 5 mm Hg the first postoperative day. Two other eyes had shallow anterior chambers, which required anterior chamber reformation. The major complications associated with the use of the valve were serous choroidal detachments in 13 eyes (22%), blockage of the tube in six eyes (10%), malposition of the tube in four eyes (7%), a suprachoroidal hemorrhage in one eye (2%), and corneal graft rejections in three (19%) of 16 eyes with corneal grafts. CONCLUSIONS Although the 12-month success with the Ahmed Glaucoma Valve implant is similar to that reported for other drainage devices, the complications associated with overfiltration in the immediate postoperative period appear to be less frequent than with other valved drainage devices. Randomized, prospective studies to compare the Ahmed Glaucoma Valve implant with other drainage devices are needed to make clinical comparisons of the different devices.

Follow-up of the original cohort with the Ahmed glaucoma valve implant

PURPOSE To study the long-term results of the Ahmed glaucoma valve implant in patients with complicated glaucoma in whom short-term results have been reported. METHODS In this multicenter study, we analyzed the long-term outcome of a cohort of 60 eyes from 60 patients in whom the Ahmed glaucoma valve was implanted. Failure was characterized by at least one of the following: intraocular pressure greater than 21 mm Hg at both of the last two visits less than 6 mm Hg at both of the last two visits, loss of light perception, additional glaucoma surgery, devastating complications, and removal or replacement of the Ahmed glaucoma valve implant. Devastating complications included chronic hypotony, retinal detachment, malignant glaucoma, endophthalmitis, and phthisis bulbi; we also report results that add corneal complications (corneal decompensation or edema, corneal graft failure) as defining a devastating complication. RESULTS The mean follow-up time for the 60 eyes was 30.5 months (range, 2.1 to 63.5). When corneal complications were included in the definition of failure, 26 eyes (43%) were considered failures. Cumulative probabilities of success at 1, 2, 3, and 4 years were 76%, 68%, 54%, and 45%, respectively. When corneal complications were excluded from the definition of failure, 13 eyes (21.5%) were considered failures. Cumulative probabilities of success at 1, 2, 3, and 4 years were 87%, 82%, 76%, and 76%, respectively. Most of the failures after 12 months of postoperative follow-up were because of corneal complications. CONCLUSIONS The long-term performance of the Ahmed glaucoma valve implant is comparable to other drainage devices. More than 12 months after the implantation of the Ahmed glaucoma valve implant, the most frequent adverse outcome was corneal decompensation or corneal graft failure. These corneal problems may be secondary to the type of eyes that have drainage devices or to the drainage device itself. Further investigation is needed to identify the reasons that corneal problems follow drainage device implantation.

Differentiating patients with glaucoma from glaucoma suspects and normal subjects by nerve fiber layer assessment with scanning laser polarimetry.

PURPOSE A study was conducted to determine normative data for nerve fiber layer measurements as obtained by scanning laser polarimetry with the Laser Diagnostic Technologies Nerve Fiber Analyzer II, identify factors affecting the measurements, and identify parameters capable of differentiating normal subjects from patients with glaucoma and patients suspected of having glaucoma because of ocular hypertension or because of a large cup-to-disc ratio (GS-disc). DESIGN A case series. PARTICIPANTS Four hundred normal subjects, 35 patients with ocular hypertension, 42 patients with glaucoma, and 17 glaucoma suspects based on optic disc appearance participated. METHODS Nerve fiber layer thickness assessments were determined in normal subjects (with normal-appearing optic nerves and normal visual fields). The results were compared to measurements from samples of age-matched patients with ocular hypertension (with normal visual fields), patients suspected of having glaucoma based on enlarged cup-to-disc ratios, and patients with open-angle glaucoma who had visual field loss. RESULTS The majority of the parameters derived from the measurements showed no significant relationship to age, although some parameters tended to decrease with increasing age. Multiple parameters showed statistically significant differences between normal subjects and patients with glaucoma. In particular, the intraellipse sector variability, an indirect measure of the shape of the nerve fiber layer in an ellipse surrounding the nerve head, showed statistically significant differences between normal subjects and patients with glaucoma as well as between glaucoma suspects and normal subjects. Similar results were seen with the superior maxima, the average thickness assessment value of the 1500 thickest points in the superior bundle. CONCLUSIONS Assessments of nerve fiber layer thickness as determined by scanning laser polarimetry can differentiate patients with glaucoma from normal subjects and may identify otherwise undetected damage in glaucoma suspects.

Original ArticlesFollow-up of the original cohort with the Ahmed glaucoma valve implant1☆

PURPOSE To study the long-term results of the Ahmed glaucoma valve implant in patients with complicated glaucoma in whom short-term results have been reported. METHODS In this multicenter study, we analyzed the long-term outcome of a cohort of 60 eyes from 60 patients in whom the Ahmed glaucoma valve was implanted. Failure was characterized by at least one of the following: intraocular pressure greater than 21 mm Hg at both of the last two visits less than 6 mm Hg at both of the last two visits, loss of light perception, additional glaucoma surgery, devastating complications, and removal or replacement of the Ahmed glaucoma valve implant. Devastating complications included chronic hypotony, retinal detachment, malignant glaucoma, endophthalmitis, and phthisis bulbi; we also report results that add corneal complications (corneal decompensation or edema, corneal graft failure) as defining a devastating complication. RESULTS The mean follow-up time for the 60 eyes was 30.5 months (range, 2.1 to 63.5). When corneal complications were included in the definition of failure, 26 eyes (43%) were considered failures. Cumulative probabilities of success at 1, 2, 3, and 4 years were 76%, 68%, 54%, and 45%, respectively. When corneal complications were excluded from the definition of failure, 13 eyes (21.5%) were considered failures. Cumulative probabilities of success at 1, 2, 3, and 4 years were 87%, 82%, 76%, and 76%, respectively. Most of the failures after 12 months of postoperative follow-up were because of corneal complications. CONCLUSIONS The long-term performance of the Ahmed glaucoma valve implant is comparable to other drainage devices. More than 12 months after the implantation of the Ahmed glaucoma valve implant, the most frequent adverse outcome was corneal decompensation or corneal graft failure. These corneal problems may be secondary to the type of eyes that have drainage devices or to the drainage device itself. Further investigation is needed to identify the reasons that corneal problems follow drainage device implantation.

Brimonidine Tartrate: A One-month Dose Response Study

BACKGROUND Brimonidine tartrate is a relatively selective alpha2-agonist that effectively reduces mean intraocular pressure (IOP) and the incidence of IOP spikes after laser trabeculoplasty. The authors were interested in evaluating the dose response of brimonidine when applied topically for a longer duration in patients with elevated IOPs. METHODS The authors conducted a 1-month, multicentered, double-masked, randomized, placebo-controlled, parallel clinical study in 194 patients with ocular hypertension or glaucoma (mean IOP, 25.6 +/- 3.2 mmHg). The authors administered three concentrations of brimonidine (0.08%, 0.2%, and 0.5%) or placebo bilaterally every 12 hours for 1 month. The authors evaluated the following parameters: IOP, heart rate, blood pressure, visual acuity, pupil size, basal tear secretion as well as patient comfort at baseline, day 1, week 1, week 3, and week 4. RESULTS All concentrations of brimonidine significantly reduced IOP, compared to baseline and placebo, at all follow-up visits. Maximum mean IOP decreases from baseline of 20.8%, 27.2%, and 30.1% were observed for the 0.08%, 0.20%, and 0.5% treatment groups, respectively. On days 1 and 21, the 0.2% and 0.5% treatment groups exhibited significantly greater IOP decreases than did the 0.08% group. After the initial steep decline in IOP, the effect decreased slightly and stabilized at day 14 at the level that was maintained throughout the study. The most frequent side effects reported were fatigue and dry mouth. No significant changes in heart rate were reported. Statistically significant decreases in mean blood pressure without clinical symptoms were observed within the 0.2% and 0.5% treatment groups. CONCLUSION Brimonidine 0.2% is well tolerated, efficacious, and shows potential as an agent in the long-term treatment of elevated IOP.

Effect of individualized compensation for anterior segment birefringence on retinal nerve fiber layer assessments as determined by scanning laser polarimetry

PURPOSE Scanning laser polarimetry estimates retinal nerve fiber layer (RNFL) thickness through measurement of retardation of a polarized laser light passing through the naturally birefringent RNFL and cornea. The commercial instrument, the GDx Nerve Fiber Analyzer (Laser Diagnostic Technologies, Inc., San Diego, CA), uses an anterior segment compensator of fixed magnitude and slow polarization axis to eliminate the contribution of the cornea to the total signal. Previous studies have shown up to 30% of patients are not adequately compensated by this method. The aim of this study was to determine the effect of individualized anterior segment compensation using a newly designed variable compensator on estimates of retinal nerve fiber layer thickness compared with those as determined with the fixed compensator in the commercial device. DESIGN Comparative, observational case series. PARTICIPANTS Twenty-eight eyes from 14 normal participants and 24 eyes from 12 patients with bilateral glaucoma. METHODS Using information derived from a scan of the macula, a newly designed variable anterior segment compensator for the GDx was set to neutralize anterior segment birefringence. Normal participants and patients with glaucoma underwent RNFL measurements using the standard (fixed) compensator and the variable compensator. The results were compared using Hotellings generalized means test and Bonferronis adjustment for multiple comparisons. MAIN OUTCOME MEASURES Standard GDx modulation and thickness parameters as determined with the fixed and variable compensators. RESULTS All thickness values were statistically significantly lower as determined with the variable compensator, with no discernible differences in any of the modulation parameters. CONCLUSIONS Individualized anterior segment compensation lowers the RNFL thickness values as determined by scanning laser polarimetry compared with those determined with the standard fixed compensator. This may narrow the normal range and increase the discriminating ability of scanning laser polarimetry between normal and disease. However, modulation is less affected, and the modulation parameters may thus prove more useful for distinguishing between normal and glaucoma.

The effect of excimer laser photorefractive keratectomy for myopia on nerve fiber layer thickness measurements as determined by scanning laser polarimetry

OBJECTIVE Scanning laser polarimetry measures the retardation of polarized laser light as it passes through the birefringent retinal nerve fiber layer (RNFL). Because retardation is directly proportional to the number of retinal nerve fibers, indirect measurements of the RNFL thickness are obtained. A fixed compensatory mechanism is used to correct for retardation attributed to birefringence in the cornea and anterior segment. Excimer laser photorefractive keratectomy (PRK) corrects myopia by ablating tissue from the cornea. This study was conducted to determine the effect of this ablation on RNFL measurements. DESIGN Prospective comparative case series. PARTICIPANTS Eighteen patients. METHODS Patients undergoing PRK had RNFL measurements performed with the GDx Nerve Fiber Analyzer (Laser Diagnostic Technologies, San Diego, CA), a scanning laser polarimeter, in both eyes before and 90 days after PRK in the first eye. MAIN OUTCOME MEASURES Fourteen different GDx parameters were analyzed for statistically significant differences preoperatively and 3 months postoperatively in the treated and untreated eye using Hotellings T-squared generalized means test. RESULTS Eighteen patients underwent PRK in the nondominant eye first. Preoperative refractions averaged -3.8+/-1.6 diopters (D), with an average correction of 3.4+/-1.9 D, corresponding to 49.7+/-20.5 microns of ablation. There were no statistically significant preoperative differences between the fellow eyes in refractive error (P = 0.65). Postoperatively, there were no statistically significant changes in any GDx parameter in the treated eye compared with the untreated control eye (P = 0.21). CONCLUSIONS Excimer laser PRK for moderate myopia has no significant effect on RNFL thickness measurements as determined by scanning laser polarimetry.