Intraocular Pressure and Medication Changes Associated with Xen Gel Stent: A Systematic Review of the Literature

The Xen gel stent (Allergan Inc, an AbbVie company; Dublin, Ireland) was conceived as an option for patients requiring modest IOP reduction but for whom trabeculectomy was not yet indicated. As with any glaucoma surgery, establishing criteria for patient selection and identifying factors that contribute to a high likelihood of success are important. To help guide clinical decision-making, a systematic review of published studies on the gel stent was performed, with the goal of understanding postoperative outcomes based on clinical and patient factors. Results were organized around a series of pertinent clinical questions based on scenarios encountered in clinical practice. Criteria for including studies were intentionally broad, with the objective of simulating the diverse population of glaucoma patients encountered in real-world practice. Outcomes for IOP and medication reduction postoperatively were assessed in various analyses, including in eyes with various glaucoma types and severity; in eyes naïve to surgery as well as those with a history of prior incisional glaucoma surgery; and when surgery was performed as a standalone procedure or at the time of cataract surgery. The results of each of the various analyses were consistent in demonstrating that successful gel stent surgery achieved a postoperative IOP of approximately 14.0 mm Hg and reduction to fewer than 1 glaucoma medication. Additional data are shown on outcomes by method of implant (ab interno vs ab externo); intraoperative use of antifibrotics; and rates of needling in published studies.

Early results of micropulse transscleral cyclophotocoagulation for the treatment of glaucoma

PURPOSE

To describe our clinical experience with the efficacy and safety of micropulse transscleral cyclophotocoagulation as a treatment for glaucoma.

METHODS

In this retrospective case series, we reviewed the charts of 95 consecutive patients with various glaucoma subtypes who underwent micropulse transscleral cyclophotocoagulation. Patients were offered micropulse transscleral cyclophotocoagulation if they had perimetric glaucoma refractory to intraocular pressure-lowering topical medications and who were poor candidates for traditional filtering surgery. Eligible patients were treated with the Micropulse P3 device (IQ 810 Laser Systems; Iridex, Mountain View, CA, USA) at 2.0-2.5 W for a duration of 90 s per hemisphere at a 31.3% duty cycle. If a retreatment was needed, the power was increased to up to 3.0 W with other parameters remaining the same. Patients were considered successfully treated if their intraocular pressure was lowered by at least 20% compared to their baseline. The main outcome measure was post-operative intraocular pressure; secondary outcome measures included the number of adverse events and complications that occurred with treatment.

RESULTS

The glaucoma subtypes treated included primary open-angle glaucoma (n = 51), exfoliation glaucoma (n = 24), chronic angle-closure glaucoma (n = 15), and congenital/juvenile glaucoma (n = 5). The mean pre-operative intraocular pressure was 25.1 ± 5.3 mm Hg and the mean post-operative intraocular pressure at 12 months was 17.5 ± 5.1 mm Hg (p = 0.004). The mean number of intraocular pressure-lowering medications used preoperatively was 3.0 ± 1.1; the mean number of medications used at the 12-month post-operative visit was 1.4 ± 1.0 (p = 0.03). Success with one treatment was achieved in 73 (76.8%) of patients. With multiple treatments, all patients had significant intraocular pressure-lowering compared to baseline. The maximum number of treatments received by any single patient was 5. There were no instances of prolonged intraocular inflammation or long-term hypotony.

CONCLUSION

Micropulse transscleral cyclophotocoagulation appears to be a safe and efficacious treatment for glaucoma. Given its improved safety profile compared to continuous-wave transscleral cyclophotocoagulation, it deserves consideration as a primary procedure.

Comparison of retinal nerve fiber layer thickness measurement bias and imprecision across three spectral-domain optical coherence tomography devices

PURPOSE

We compared retinal nerve fiber layer (RNFL) bias and imprecision among three spectral-domain optical coherence tomographs (SD-OCT).

METHODS

A total of 152 eyes of 83 subjects (96 healthy and 56 glaucomatous eyes) underwent peripapillary RNFL imaging using at least 2 of the following 3 SD-OCT devices on the same day: Cirrus HD-OCT (optic nerve head [ONH]) cube 200 × 200 protocol), RTVue-100 (ONH protocol [12 radial lines and 13 concentric circles]), and 3D OCT-1000 (3D Scan 256 × 256 protocol). Calibration equations, bias and imprecision of RNFL measurements were calculated using structural equation models.

RESULTS

The calibration equations for healthy and glaucoma RNFL thickness measurements among the 3 devices were: Cirrus = 2.136 + 0.831*RTVue; Cirrus = -15.521 + 1.056*3D OCT-1000; RTVue = -21.257 + 1.271*3D OCT-1000. Using Cirrus bias as an arbitrary reference, RTVue bias was 1.20 (95% CI 1.09-1.32, P < 0.05) times larger and 3D OCT-1000 was 0.95 (0.87-1.03, P > 0.05) times smaller. Relative to 3D OCT-1000, the RTVue bias was 1.27 (1.13-1.42, P < 0.05). RTVue imprecision (healthy eyes 7.83, 95% CI 6.43-9.58; glaucoma cases 5.71, 4.19-7.64) was statistically significantly higher than both Cirrus (healthy eyes 3.23, 2.11-4.31; glaucoma cases 3.53, 0.69-5.24) and 3D OCT-1000 (healthy eyes 4.07, 3.11-5.35; glaucoma cases 5.33, 3.77-7.67) in healthy eyes. The imprecision also was significantly higher for RTVue measurements in healthy compared to glaucomatous eyes. None of the other comparisons was statistically significant.

CONCLUSIONS

RTVue-100 showed higher imprecision (or higher measurement variability) than Cirrus HD-OCT and 3D OCT-1000 RNFL measurements. Three-dimensional cube scanning with post-hoc data sampling may be a factor reducing imprecision.

Evaluating objective and subjective quantitative parameters at the initial visit to predict future glaucomatous visual field progression

BACKGROUND AND OBJECTIVE

To evaluate the ability of structural assessment to predict glaucomatous visual field progression.

PATIENTS AND METHODS

A total of 119 healthy eyes with suspected glaucoma and glaucomatous eyes with 5 or more optic nerve stereophotographs, optical coherence tomography (OCT), and confocal scanning laser ophthalmoscopy (CSLO) all acquired within 6 months of each other were enrolled. Odds ratios to predict progression were determined by generalized estimating equation models.

RESULTS

Median follow-up was 4.0 years (range: 1.5 to 5.7 years). Fifteen eyes progressed by glaucoma progression analysis, 20 by visual field index, and 10 by both. Baseline parameters from stereophotographs (vertical cup-to-disc ratio and Disc Damage Likelihood Scale), OCT (global, superior quadrant, and inferior quadrant retinal nerve fiber layer thickness), and CSLO (cup shape measure and mean cup depth) were significant predictors of progression. Comparing the single best parameter from all models, only the OCT superior quadrant RNFL predicted progression.

CONCLUSION

Baseline stereophotographs, OCT, and CSLO measurements may be clinically useful to predict glaucomatous visual field progression.

A comparison of active ingredients and preservatives between brand name and generic topical glaucoma medications using liquid chromatography-tandem mass spectrometry

BACKGROUND

This work compares the concentration of active ingredients and preservatives in commonly used brand name versus generic glaucoma medications.

MATERIALS AND METHODS

Active ingredient and benzalkonium chloride (BAK) concentrations in brand name latanoprost and dorzolamide-timolol were each compared to two generic counterparts using liquid chromatography-mass spectrometry at baseline and after exposure to 25°C and 50°C for 30 days. Micro flow imaging was used to quantify particulate material greater than one micron in diameter.

RESULTS

Brand name formulations contained active ingredients and BAK in concentrations that were generally in agreement with their package inserts at baseline. The two generic formulations of latanoprost contained baseline levels of active ingredients that were 10% greater than their labeled value. Generic latanoprost formulations had significant loss of active ingredient concentration after exposure to 25°C and 50°C for 30 days. Both generic and brand name dorzolamide-timolol appeared relatively resistant to degradation. BAK concentrations remained stable at 25°C but decreased in some bottles at 50°C. Bottles of both generic medications had higher levels of particulate matter compared to brand name versions.

CONCLUSIONS

Exposure to temperatures at the high end of the labeled value may lead to a significant decrease in concentration of active ingredients in generic formulations that could influence clinical efficacy. Re-evaluation of intraocular pressure lowering efficacy may be indicated in glaucoma patients switching from brand name to generic formulations.

Recurrent enterococcal endophthalmitis seeded by an intraocular lens biofilm

A case of endophthalmitis following uneventful phacoemulsification and posterior chamber intraocular lens (IOL) implantation in a 77-year-old diabetic man was culture-positive for Enterococcus faecalis. After successful treatment with intravitreal, topical, and systemic antibiotic agents, the infection seemed to clear and the patient achieved a corrected visual acuity of 20/25. Four months after the initial presentation, the patient again developed signs and symptoms of endophthalmitis, with regrowth of E faecalis. The antibiotic therapy was repeated. One month later, the IOL was removed surgically and found to harbor a biofilm of the strain demonstrated by DNA analysis. The microbiologic and DNA analyses support that a biofilm on an IOL could be a vector for a cause of recurrent endophthalmitis. Intraocular lens exchange in cases of postoperative endophthalmitis caused by E faecalis may be considered to decrease the risk for recurrent infection.

Variation in optical coherence tomography signal quality as an indicator of retinal nerve fibre layer segmentation error

PURPOSE

Commercial optical coherence tomography (OCT) systems use global signal quality indices to quantify scan quality. Signal quality can vary throughout a scan, contributing to local retinal nerve fibre layer segmentation errors (SegE). The purpose of this study was to develop an automated method, using local scan quality, to predict SegE.

METHODS

Good-quality (global signal strength (SS) ≥ 6; manufacturer specification) peripapillary circular OCT scans (fast retinal nerve fibre layer scan protocol; Stratus OCT; Carl Zeiss Meditec, Dublin, California, USA) were obtained from 6 healthy, 19 glaucoma-suspect and 43 glaucoma subjects. Scans were grouped based on SegE. Quality index (QI) values were computed for each A-scan using software of our own design. Logistic mixed-effects regression modelling was applied to evaluate SS, global mean and SD of QI, and the probability of SegE.

RESULTS

The difference between local mean QI in SegE regions and No-SegE regions was -5.06 (95% CI -6.38 to 3.734) (p<0.001). Using global mean QI, QI SD and their interaction term resulted in the model of best fit (Akaike information criterion=191.8) for predicting SegE. Global mean QI ≥ 20 or SS ≥ 8 shows little chance for SegE. Once mean QI<20 or SS<8, the probability of SegE increases as QI SD increases.

CONCLUSIONS

When combined with a signal quality parameter, the variation of signal quality between A-scans provides significant information about the quality of an OCT scan and can be used as a predictor of segmentation error.

The management of glaucoma and intraocular hypertension: current approaches and recent advances

In the last decade, numerous novel ocular hypotensive agents have been introduced for the control of intraocular pressure (IOP). Clinicians now have more options than ever in the selection of medical therapy for the treatment of glaucoma and ocular hypertension. When selecting an ocular hypotensive medication for their patients, clinicians should consider not only the IOP-lowering efficacy of an agent, but also the ability of the drug to allow patients to achieve target levels of IOP that are low enough to stop the progression of glaucomatous damage. Other considerations should include how well the drug controls diurnal IOP, the likelihood of serious adverse events, the versatility of the medication for use as an adjunctive agent, as well as other potential attributes (ie, neuroprotection).

Effects of benzalkonium chloride- and polyquad-preserved combination glaucoma medications on cultured human ocular surface cells

INTRODUCTION

The aim of this study is to investigate potential adverse effects of fixed combination glaucoma medications preserved with either benzalkonium chloride (BAK) or Polyquad® (PQ; Alcon Research Ltd., Fort Worth, TX, USA) on cultured ocular epithelial cells.

METHODS

Confluent cultures of human cornea and conjunctival cell lines were exposed for 25 minutes to different glaucoma medications as well as a range of concentrations of BAK (0.001%-0.050%). Balanced salt solution was used as the "live" control and a solution containing 70% methanol and 0.2% saponin was used as a "dead" control. The number of dead and live cells were determined via ethidium homodimer (Eth-1) and calcein acetoxymethyl ester (AM) fluorescence, respectively.

RESULTS

The toxicity of the prostaglandin analog with beta-blocker timolol fixed-combination formulations preserved with BAK was different from that observed in the respective BAK concentrations. Travoprost plus timolol fixed combination with BAK performed better than its respective BAK concentration alone, while the latanoprost plus timolol fixed combination performed worse than its respective BAK concentration. Travoprost plus timolol fixed combination preserved with PQ had greater corneal and conjunctival cell survival than either the travoprost plus timolol fixed combination preserved with BAK or the latanoprost plus timolol fixed combination.

CONCLUSION

Ocular surface side effects have previously been demonstrated with chronic, long-term exposure to intraocular-pressure-lowering medications containing the common preservative BAK. BAK alone has significant in-vitro cytotoxicity to cultured ocular epithelial cells. Substitution of BAK with PQ resulted in significantly higher percentages of live conjunctival and corneal cells. Further studies are needed to understand the clinical implications of these findings.

Intracameral dexamethasone reduces inflammation on the first postoperative day after cataract surgery in eyes with and without glaucoma

Purpose:

To evaluate whether dexamethasone injected intracamerally at the conclusion of surgery can safely and effectively reduce postoperative inflammation and improve surgical outcomes in eyes with and without glaucoma.

Methods:

Retrospective chart review of 176 consecutive eyes from 146 patients receiving uncomplicated phacoemulsification (PE) (n = 118 total, 82 with glaucoma), glaucoma drainage device (GDD) (n = 35), combined PE/GDD (n = 11) and combined PE/endoscopic cyclophotocoagulation (n = 12). Ninety-one eyes from 76 patients were injected with 0.4 mg dexamethasone intracamerally at the conclusion of surgery. All eyes received standard postoperative prednisolone and ketorolac eyedrops. Outcomes were measured for four to eight weeks by subjective complaints, visual acuity (VA), slit-lamp biomicroscopy, intraocular pressure (IOP) and postoperative complications.

Results:

Dexamethasone significantly reduced the odds of having an increased anterior chamber (AC) cell score after PE (p = 0.0013). Mean AC cell score ± SD in nonglaucomatous eyes was 1.3 ± 0.8 in control and 0.8 ± 0.7 with dexamethasone; scores in glaucomatous eyes were 1.3 ± 0.7 in control and 0.9 ± 0.8 with dexamethasone. Treated nonglaucomatous eyes had significantly fewer subjective complaints after PE (22.2% vs 64.7% in control; p = 0.0083). Dexamethasone had no significant effects on VA, corneal changes, IOP one day and one month after surgery, or long-term complications.

Conclusions:

Intracameral dexamethasone given at the end of cataract surgery significantly reduces postoperative AC cells in eyes with and without glaucoma, and improves subjective reports of recovery in nonglaucomatous eyes. There were no statistically significant risks of IOP elevation or other complications in glaucomatous eyes.

Trabeculectomy with intraoperative retrobulbar triamcinolone acetonide

Use of topical steroids is an important component of postoperative care after filtration surgery. Efficacy of postoperative medications is affected by patient adherence and physical limitations in the elderly population often prohibit proper dosing of ophthalmic drops. We describe a technique for the use of intraoperative retrobulbar triamcinolone acetonide in trabeculectomy surgery and report on postoperative outcomes. This technique appears safe and may be an attractive method of delivering a steroid depot at the time of trabeculectomy.

Relationship between glaucoma and selenium levels in plasma and aqueous humour

AIM

The aim of the study was to compare selenium levels in plasma and aqueous humour in subjects with and without primary open-angle glaucoma (POAG).

METHODS

Forty-seven POAG cases and 54 controls in this case-control study were recruited from surgery patients at the University Physician's Ophthalmology Clinic in Tucson, Arizona, USA. Aqueous humour and plasma selenium were determined by high-performance liquid chromatography ion channel plasma mass spectrometry (HPLC ICP-MS). Potential confounders were assessed via a questionnaire. Biological samples were collected and processed at surgery and analysed for selenium content after collection was complete. Outcome measures included the odds of glaucoma in relationship to plasma selenium, aqueous humour selenium, and the ratio of levels of aqueous humour selenium to plasma selenium.

RESULTS

Tertile of selenium and its relationship to POAG was examined. After adjustment for common glaucoma risk factors, the odds of glaucoma in the highest tertile of plasma selenium (OR = 11.3; p = 0.03) and the middle tertile of aqueous humour selenium (OR = 0.06; p = 0.02) was significantly associated with glaucoma.

CONCLUSION

Although a causal pathway cannot be inferred from our analysis, our data, added to that of others, suggest that the pathology is selenium-related.

Comparison of corneal and conjunctival changes after dosing of travoprost preserved with sofZia, latanoprost with 0.02% benzalkonium chloride, and preservative-free artificial tears

PURPOSE

To evaluate corneal and conjunctival changes after chronic, once-daily dosing of travoprost preserved with sofZia, latanoprost preserved with 0.02% benzalkonium chloride (BAK), or preservative-free artificial tears.

METHODS

Thirty New Zealand white rabbits were randomized to receive once-daily instillation of travoprost with sofZia, latanoprost, or preservative-free artificial tears in 1 eye. Corneal epithelial changes were evaluated by transmission electron microscopy and graded on a standard scale by 2 masked observers. Conjunctival inflammation was evaluated by light microscopy after hematoxylin and eosin staining. Lymphocytes were counted in the epithelium and superficial stroma by 2 masked observers and compared among groups.

RESULTS

Corneal tissue treated with preservative-free artificial tears and travoprost with sofZia revealed similar changes under transmission electron microscopy (P = 0.53). Significantly more corneal epithelial damage was noted with latanoprost than travoprost with sofZia (P = 0.0001). The number of lymphocytes in the conjunctival epithelium and stroma was significantly lower in eyes treated with travoprost with sofZia than eyes treated with latanoprost (P = 0.0001). The number of conjunctival lymphocytes was similar among conjunctival specimens exposed to travoprost with sofZia and preservative-free artificial tears (P = 0.65).

CONCLUSIONS

Once-daily dosing of travoprost with sofZia produced significantly fewer corneal changes and less conjunctival inflammation than latanoprost preserved with BAK. Corneal and conjunctival changes noted with travoprost with sofZia were similar to those induced by preservative-free artificial tears. Glaucoma medication with high levels of BAK may cause more deleterious effects on the ocular surface than non-BAK-preserved medications. Human studies are needed to better understand the clinical effects of different preservative types and concentrations on the ocular surface.

The effect of probe placement and type of viscoelastic material on endoscopic cyclophotocoagulation laser energy transmission

BACKGROUND AND OBJECTIVE

Endoscopic cyclophotocoagulation is a laser modality used to treat refractory glaucoma through the ablation of ciliary epithelium on the ciliary processes, which results in reduced aqueous production. The purpose of this study was to investigate the effect of various viscoelastics and optimal probe positioning on endoscopic cyclophotocoagulation treatment.

MATERIALS AND METHODS

Six different viscoelastic materials and a balanced salt solution, which was used as a control, were evaluated by placing 2 mL of each in a separate 2 mL glass tube. Laser power was measured at six distances to represent clinical placement of the laser probe in relation to the ciliary processes.

RESULTS

The amount of energy measured with the probe at the bottom of the tube and 1 and 2 mm away was not statistically significantly different among the viscoelastic materials or the balanced salt solution. There was a gradual decrease in transmission of laser energy in all viscoelastics as the laser probe was moved farther away.

CONCLUSION

To preserve the intended laser energy setting, the optimal distance between the treated tissue and the laser probe is 2 mm.

Evaluation of circadian control of intraocular pressure after a single drop of bimatoprost 0.03% or travoprost 0.004%

PURPOSE

To compare circadian control of intraocular pressure (IOP) after a single drop of bimatoprost 0.03% or travoprost 0.004% in patients with glaucoma or ocular hypertension.

METHODS

Randomized, investigator-masked, paired-eye, 36-hour clinical comparison. After completing a washout, patients (N = 19) were randomized to a single drop of bimatoprost in one eye and travoprost in the other eye at 8 PM. At night, IOP was measured with patients lying in bed and sitting. IOP was measured every 4 h for 36 h in total.

RESULTS

Mean IOP at 8 PM (prior to drop instillation) was 20.6 mmHg (18.5-24.0 mmHg) with the bimatoprost eye group and 21.1 mmHg (18.5-26.5 mmHg) with the travoprost eye group (p = 0.369). At every measurement, both bimatoprost and travoprost significantly reduced IOP from baseline. During the first 24 h, mean IOP (while sitting) after instillation of a single drop of study medication ranged from 17.8 to 19.7 mmHg with bimatoprost and from 17.2 to 20.0 mmHg with travoprost (p > or = 0.075). While in the supine position, IOP ranged from 21.6 to 24.9 mmHg with bimatoprost and from 21.1 to 25.2 mmHg with travoprost (p > or = 0.351). Both medications continued to control IOP for the remaining 12 h, with IOP approaching baseline after 36 h (mean IOP of 20.5 mmHg with bimatoprost and 21.5 mmHg with travoprost, p = 0.381). Study limitations included single-drop instillation and a short follow-up time.

CONCLUSIONS

This marks the first time a single drop has been used for this type of evaluation. These findings suggest that both bimatoprost and travoprost provide comparable and lasting control of circadian IOP in patients with glaucoma or ocular hypertension.

A multicentre evaluation of the effect of patient education on acceptance of hyperaemia associated with bimatoprost therapy for glaucoma or ocular hypertension

INTRODUCTION

The aim of this study was to evaluate the incidence of hyperaemia in patients using bimatoprost and to determine if simple interventions result in increased understanding of glaucoma and hyperaemia.

METHODS

This was a multicentre, open-label, evaluator-masked clinical trial of 106 patients. Prior to enrolling in the trial, patients were washed out from any ocular hypotensive medications and prescribed bimatoprost daily in the evening for 6 weeks. Patients were randomised to one of two groups: intervention and no intervention. Patients in the intervention group (n=63) were given a fact sheet explaining the importance of reducing intraocular pressure (IOP) and the efficacy of bimatoprost, while patients in the no intervention group (n=43) were instructed only to instil bimatoprost daily and were given no additional instructions.

RESULTS

As graded by the masked investigators, conjunctival hyperaemia peaked 1 day after commencing bimatoprost, with a mean of 1.2 (0=none, 0.5=trace, 1=mild, 2=moderate, 3=severe). By day 7, hyperaemia levels were approximately trace (0.79) and continued to decrease throughout the study. There were no significant differences between groups in mean conjunctival hyperaemia at any study visit (P> or =0.215). At every visit, patients in the intervention group were significantly more likely than patients in the no intervention group to report that lowering IOP was very important for preserving vision (P< or =0.001). At week 6, 98% of patients in the intervention group reported that IOP-lowering was very important for preserving vision, compared with 76% of patients who did not receive the intervention (P< or =0.001). Patients in the intervention group were more likely than patients in the no intervention group to be willing to continue to use bimatoprost, despite hyperaemia. This difference was statistically significant at day 1 (P=0.003).

CONCLUSION

Patients were not bothered by the trace.mild hyperaemia associated with bimatoprost therapy. Patient education can improve patient acceptance of a prescribed regimen and potentially increase compliance.

One-site Versus Two-site Endoscopic Cyclophotocoagulation

PURPOSE

To report the intraocular pressure (IOP) lowering effect of endoscopic cyclophotocoagulation (ECP) treatment through 1 versus 2 corneal incisions.

METHODS

This is a retrospective consecutive case review of combined ECP and phacoemulsification (PE). Group 1 included patients undergoing PE-ECP through 1 clear cornea incision and group 2 involved PE followed by ECP through 2 incisions. The 1 versus 2 site selection was performed in a nonrandomized fashion at the time of surgery. Data including age, sex, preoperative diagnosis, number of preoperative and postoperative glaucoma medications, complications, treatment failures, and IOP were collected and analyzed using analysis of variance and t tests where appropriate.

RESULTS

Group 1 included 15 patients and group 2 included 25 patients. Age of patients in group 1 (66.07+/-17.73) and group 2 (73.48+/-11.31) were similar (P=0.11). Visual acuity in group 1 ranged from 20/40 to 20/400 and from 20/40 to counting fingers in group 2. The preoperative diagnoses were similar between the 2 groups. Preoperative IOP was 23.60+/-3.89 in group 1 and 24.48+/-8.99 in group 2 (P=0.72). IOP decreased in group 1 from 23.60+/-3.89 to 17.93+/-4.38 (P=0.0008) and in group 2 from 24.48+/-8.99 to 13.88+/-3.22 (P=0.00001) with 3 months of follow-up. IOP at 3 months was significantly lower in group 2 compared with group 1 (P=0.002). Six-month IOP data for group 1 (16.00+/-2.77) and group 2 (13.00+/-3.09) remained statistically significant in favor of 2-site PE-ECP (P=0.04). Glaucoma medication use decreased more in group 2 (2.56+/-0.71 to 0.52+/-0.59) versus group 1 (2.47+/-0.74 to 1.93+/-0.88) (P=0.00001).

CONCLUSIONS

Two-site PE-ECP may result in statistically significant IOP lowering and less dependence on glaucoma medications compared with single site PE-ECP.

Travoprost 0.004%/timolol 0.5% fixed combination

Fixed-combination travoprost/timolol solution consists of travoprost 0.004% and timolol 0.5%. Several studies have demonstrated the efficacy and safety of this medication used once daily for the treatment of open-angle glaucoma and ocular hypertension. This fixed combination has been compared to travoprost and timolol used concomitantly, latanoprost and timolol used concomitantly, latanoprost/timolol fixed combination and travoprost and timolol monotherapy. Fixed-combination medicines such as travoprost/timolol offer the potential of maximizing patient adherence by decreasing the burden of using multiple topical agents that lower intraocular pressure, and by potentially decreasing the overall cost to both the patient and the health-care system. We discuss the benefits of fixed-dose medications, report on previous clinical trials and summarize the existing data on the performance of travoprost/timolol.

Endoscopic cyclophotocoagulation using iris hooks versus viscoelastic devices

Endoscopic cyclophotocoagulation utilizes a diode laser to ablate ciliary body epithelium, resulting in decreased intraocular pressure. Viscoelastic devices are often used to elevate the iris for improved exposure and efficient treatment of targeted tissue. Occasionally, early postoperative intraocular pressure spikes may occur due to retained viscoelastic material. Iris hooks may provide a safe alternative for elevation of the iris during endoscopic cyclophotocoagulation treatment and may be particularly advantageous in cases of aphakia or posterior capsule compromise in which viscoelastic removal is made more difficult.

Peripapillary schisis in glaucoma patients with narrow angles and increased intraocular pressure

PURPOSE

To describe two cases of peripapillary retinal schisis in patients with glaucoma without evidence of optic nerve pits, pseudopits, or X-linked retinoschisis.

DESIGN

Two observational case reports and literature review.

METHODS

Imaging of the peripapillary nerve fiber layer and schisis cavities was completed in two patients, and one patient was followed over time.

RESULTS

The first patient, diagnosed with narrow angle glaucoma, was noted to have peripapillary schisis in the right eye with matching changes on visual field and optical coherence tomographic (OCT) results. Follow-up examination revealed that the schisis disappeared in the right eye while appearing in the left. The findings were verified with high-speed ultra-high-resolution OCT performed in both eyes. The second case involved a patient with anatomically narrow angles, high intraocular pressure (IOP), and peripapillary schisis extending into the macula.

CONCLUSIONS

Peripapillary retinoschisis may represent a unique sequelae of intraocular fluctuations in patients with uncontrolled glaucoma. Further studies are needed to better understand this disease process.

Comparison of acute structural and histopathological changes of the porcine ciliary processes after endoscopic cyclophotocoagulation and transscleral cyclophotocoagulation

BACKGROUND

The objective of this study is to investigate the acute histological effects of transscleral cyclophotocoagulation and endoscopic cyclophotocoagulation on the ciliary body and other structures of porcine eyes compared with untreated controls.

METHODS

Transscleral cyclophotocoagulation and endoscopic cyclophotocoagulation were performed on porcine eyes. Detailed histological evaluations were performed with light and scanning electron microscopy of treated eyes and compared with untreated controls.

RESULTS

Histological changes were observed with both light and scanning electron microscopy for all treated tissues. Tissue treated with transscleral cyclophotocoagulation showed pronounced tissue disruption of the ciliary body muscle and stroma, ciliary processes, and both pigmented and non-pigmented ciliary epithelium. Endoscopic cyclophotocoagulation-treated tissue exhibited pronounced contraction of the cilliary processes with disruption of the ciliary body epithelium, with less architectural disorginization and sparing of the ciliary body muscle. The sclera was not affected by either laser treatment.

CONCLUSION

The endoscopic cyclophotocoagulation treatment caused less damage to the ciliary body compared with the transscleral cyclophotocoagulation when evaluated by light and scanning electron microscopy. Compared with transscleral cyclophotocoagulation, endoscopic cyclophotocoagulation appears to be a more selective form of cyclophotocoagulation resulting in less tissue disruption while achieving the goal of destroying ciliary body epithelium.

Evaluation of adherence to morning versus evening glaucoma medication dosing regimens

PURPOSE

Compare patient adherence to glaucoma therapy with morning versus evening dosing schedules.

METHODS

Retrospective chart review of 41 consecutive patients who had used the Travatan Dosing Aid (Alcon, Fort Worth, TX). Patients had been nonrandomly assigned morning or evening dosing at initiation of usage. Dosing aid data was recorded and analyzed using paired student t-tests where appropriate. Adherence was defined as the dose being administered within 3 hours of the prescribed dosing time.

RESULTS

Records of 18 patients in the morning group and 23 in the evening group were reviewed. Average time of use was 51.06 +/- 4.94 days for the morning group and 50.65 +/- 5.38 days for the evening group (p = 0.80). Patients taking the morning dose were less likely to miss an entire day of dosing (days missed in morning group = 3.33 +/- 1.33; evening group = 5.87 +/- 1.52, p < 0.001). The overall adherence rate was not statistically different between groups (morning group = 82.72 +/- 7.32%; evening group = 78.96 +/- 6.12%, p = 0.08) although the morning group tended to be more adherent to therapy. Patients in the morning group were also more likely to take their drops later rather than miss the entire day's dose.

CONCLUSIONS

The rate of adherence for both the morning and evening dosing groups was better than previously reported. Dosing drops in the morning, rather than in the evening, may lead to fewer entirely missed days of glaucoma eye drop therapy.

Ocular hypotensive efficacy of brimonidine 0.15% as adjunctive therapy with latanoprost 0.005% in patients with open-angle glaucoma or ocular hypertension

This study was undertaken to evaluate the ocular hypotensive efficacy of brimonidine Purite 0.15% (Alphagan P 0.15%; Allergan, Inc., Irvine, Calif) given as adjunctive therapy with latanoprost 0.005% (Xalatan; Pfizer Inc., New York, NY( to patients with open-angle glaucoma or ocular hypertension. In this multicenter, open-label, prospective evaluation, the intraocular pressure (IOP) of the 43 enrolled patients was > or =18 mm Hg after at least 6 wk of latanoprost monotherapy. The primary outcome measure was IOP at peak drug effect )10 AM, or approximately 2 h after the morning dose of brimonidine 0.15%(. IOP at trough drug effect (8 AM, or approximately 12 h after the evening dose of brimonidine) was also measured. Baseline IOP was 21.9 (+/-2.3) mm Hg. After 1 mo of treatment, additional mean IOP reductions from latanoprost-treated baseline values were 5.8 mm Hg (26%) at peak drug effect (P<.001) and 3.3 mm Hg (15%) at trough (P<.001). At the month 2 visit, additional mean IOP reductions from latanoprost-treated baseline values were 5.1 mm Hg (23%) at peak drug effect (P<.001) and 2.0 mm Hg (9%) at trough (P=.002). Brimonidine Purite 0.15% provided statistically significant additional reductions in IOP from latanoprost-treated baseline values. These findings suggest that brimonidine Purite 0.15% is an efficacious adjunctive therapy in patients given latanoprost who require additional lowering of IOP.

Comparing bimatoprost and travoprost in black Americans

OBJECTIVE

To compare the intraocular pressure-lowering efficacy and safety of topical bimatoprost 0.03% with that of travoprost 0.004% for the treatment of black patients with open-angle glaucoma (OAG) and ocular hypertension (OHT).

RESEARCH DESIGN AND METHODS

Multicenter, prospective, randomized, investigator-masked trial of 94 black patients previously diagnosed with OAG or OHT. All patients completed washout of ocular hypotensive medications before study participation. Patients were assigned to either once-daily bimatoprost 0.03% or once-daily travoprost 0.004% for 3 months.

MAIN OUTCOME MEASURES

The primary outcome measures were mean intraocular pressure (IOP), mean change from baseline IOP, and percentage of patients who reached a target IOP reduction. Secondary measures included ophthalmologic examination and adverse events.

RESULTS

Both bimatoprost and travoprost significantly lowered IOP at all study visits (p < 0.001). Bimatoprost provided mean IOP reductions from baseline that ranged from 6.8 mmHg to 7.8 mmHg (27% to 31%). Travoprost provided mean IOP reductions from baseline that ranged from 6.2 mmHg to 6.9 mmHg (25% to 28%). By month 3, 85% of participants in the bimatoprost group had a mean IOP reduction of at least 20%, compared with 68% of those in the travoprost group. Furthermore, 31.9% of those in the bimatoprost group had a mean IOP reduction of more than 40% at month 3 compared with 20.9% of those in the travoprost group. There were no significant differences in biomicroscopy, ophthalmoscopy, or visual acuity. Ocular redness was the most commonly reported adverse event in both treatment groups. No serious adverse events were reported.

CONCLUSIONS

Bimatoprost and travoprost each effectively lowered IOP in this population of black patients. More patients achieved clinically relevant IOP reductions with bimatoprost.

Comparison of acute structural and histopathological changes in human autopsy eyes after endoscopic cyclophotocoagulation and trans-scleral cyclophotocoagulation

AIM

To study the histological effects of trans-scleral cyclophotocoagulation (TCP) and endoscopic cyclophotocoagulation (ECP) on the ciliary body and other structures collected at autopsy and to compare with untreated controls.

MATERIALS AND METHODS

TCP and ECP were performed on human eyes at autopsy. Detailed histological evaluations were perfomed using light microscopy and scanning electron microscopy on treated eyes and compared with untreated controls.

RESULTS

Histological changes were observed with both light microscopy and scanning electron microscopy for all treated tissues. Tissue treated with TCP showed pronounced tissue disruption of the ciliary body muscle and stroma, ciliary processes, and both pigmented and non-pigmented ciliary epithelium. ECP-treated tissue exhibited pronounced contraction of the ciliary processes with disruption of the ciliary body epithelium, sparing of the ciliary body muscle and less architectural disorganisation. The sclera was not affected by either laser treatment.

CONCLUSIONS

ECP treatment caused less damage to the ciliary body compared with TCP when evaluated by light microscopy and scanning electron microscopy. Compared with TCP, ECP seems to be a more selective form of cyclophotocoagulation, resulting in less tissue disruption while achieving the goal of destroying ciliary body epithelium.

Fibrin glue-assisted glaucoma drainage device surgery

AIM

To describe the use of fibrin glue as a suture substitute for portions of glaucoma drainage device (GDD) surgery.

METHODS

Retrospective non-randomised case-control study reviewing 28 consecutive cases of GDD implantation using traditional suture material compared with 14 consecutive cases of GDD implantation using Tisseel fibrin glue (Baxter AG, Vienna, Austria) for portions of the procedure. The fibrin glue was used to close the conjunctiva, secure the pericardium patch graft and secure the tube to the sclera. Three-month follow-up data for each group as well as data on operating times, postoperative conjunctival inflammation, drugs used for glaucoma and intraocular pressure (IOP) were evaluated. Statistical analysis was carried out using analysis of variance.

RESULTS

The mean (SD) age of the patients in the suture group (17 men and 11 women) was 56.6 (10.5) years and that in the Tisseel-assisted group (8 men and 6 women) was 54.7 (8.6) years (p = 0.56). No significant differences were observed in IOP levels at any time point between the two groups. No significant differences were found for the need for postoperative glaucoma drops or postoperative complication rates in both groups. Conjunctival inflammation was more pronounced in the suture group (p = 0.002) using a standard scale for comparison. The mean (SD) time of surgery was significantly less for the Tisseel-assisted group, 15.0 (3.11) min, than for the suture group, 25.93 (4.04) min (p<0.001).

CONCLUSIONS

Tisseel fibrin glue seems to be a safe substitute for some of the sutures used in GDD surgery. Use of Tisseel seems to have no effect on IOP control or complications, whereas it considerably improved postoperative conjunctival inflammation and reduced time of surgery. Further studies are needed to better understand the role of fibrin glue in GDD implantation.

Accuracy and performance of a commercially available Dosing Aid

AIM

To evaluate the recently introduced Travatan Dosing Aid (TDA) for its accuracy in recording and dispensing eyedrops.

METHODS

The number of eyedrops dispensed with each lever depression and agreement of total number of drops dispensed with that recorded by the device was evaluated in a controlled setting.

RESULTS

The TDA correctly recorded a drop being dispensed 100% of the time with full TDA lever depression for <3 s. Under these conditions, agreement between numbers of drops dispensed and recorded was 99%. However, failure to fully depress the lever or prolonged lever depression for >4 s resulted in unreliable TDA recording.

CONCLUSION

Eyedrops were reliably recorded by the TDA after each full lever depression. However, patients need to be instructed about optimal technique so that evaluation of compliance is not confounded by mechanical factors.

Trypan blue–assisted neodymium:YAG laser treatment for overfiltering bleb

Overfiltering blebs can lead to postoperative problems including hypotony maculopathy, decreased vision, and increased ocular discomfort. Many methods have been used in the past with varying results. Various lasers have been used in an attempt to cause localized scarring and fibrosis. We report a treatment technique to noninvasively treat a patient with an overfiltering bleb using trypan blue and a frequency-doubled continuous-wave neodymium:YAG laser emitting green light.

Effect of corneal drying on optical coherence tomography

PURPOSE

To determine the effect of corneal drying on the outcome of optical coherence tomography (OCT).

DESIGN

Cohort study.

PARTICIPANTS

Seventeen normal participants (mean age, 39+/-12 years).

METHODS

Subjects underwent a series of peripapillary circular StratusOCT scans (version 3.0; Carl Zeiss Meditec, Inc., Dublin, CA) in a randomly selected eye. Baseline scan sets were acquired, and thereafter, blinking was prevented by taping the eyelid. Eyelid taping was immediately followed by 6 to 8 serial scan sets, each separated by 20 seconds. After removing the eyelid tape, 3 additional scans were acquired at 1, 2, and 4 minutes of blinking freely.

MAIN OUTCOME MEASURES

The analyzed outcome measures were scan quality as defined by signal-to-noise ratio (SNR) and signal strength (SS) provided by the built-in OCT software and mean nerve fiber layer (NFL) thickness.

RESULTS

Significant reductions in SNR, SS, and NFL were noted at each scanning point in the drying phase (for each, P<0.015, paired t test) except for NFL thickness measurements acquired at 140 and 160 seconds. The reduction in NFL thickness exceeded the 95% confidence limit of the reported reproducibility error of StratusOCT after 15 seconds of corneal drying. After 1 and 2 minutes of blinking freely, there was still a significant reduction in NFL thickness compared with the baseline value, which was no longer evident at the 4-minute scan.

CONCLUSIONS

Corneal dryness affects OCT scan quality and measured NFL thickness after a short exposure time. It is recommended to instruct those who are scanned to blink frequently or to instill artificial tears.

Comparison of Initial Treatment Response to Two Enhanced-Viscosity Artificial Tears

PURPOSE

To compare the effectiveness of 1.0% carboxymethylcellulose (CMC) (Refresh Liquigel, Allergan, Inc., Irvine, CA) and propylene glycol/polyethylene glycol 400 (PG-HPG) (Systane, Alcon, Fort Worth, TX) in providing relief of dry eye symptoms and signs.

METHODS

To evaluate patient comfort and drop preference, patients were given CMC in one eye and PG-HPG in the other. Five minutes after the initial drop application, patients were questioned on overall preference and comfort, as measured by stickiness, blurring, and soothing. Patients were then randomized to receive CMC or PG-HPG in both eyes for 1 week. Fluorescein staining was evaluated at baseline and week 1.

RESULTS

Of patients with a preference, more patients preferred CMC than PG-HPG. Thirty-six percent preferred CMC, and 24% preferred PG-HPG. More (35%) patients found CMC to be more soothing than PG-HPG (22%). After 1 week of treatment, eyes treated with CMC consistently showed less ocular surface staining than did eyes treated with PG-HPG. Mean corneal staining score in the inferior region was significantly lower in the CMC group than in the PG-HPG group (P = 0.008) at week 1. CMC provided a statistically significant decrease in mean corneal inferior staining (P < 0.001), whereas the PG-HPG group (P = 0.185) had no significant change. In the temporal conjunctival region, CMC provided a significantly lower mean staining score than PG-HPG after 1 week of treatment (P = 0.005).

CONCLUSIONS

Patients found CMC to be more comfortable than PG-HPG. After 1 week of use, CMC provided greater relief of dry eye signs and symptoms than PG-HPG.

A 3-month clinical trial comparing the IOP-lowering efficacy of bimatoprost and latanoprost in patients with normal-tension glaucoma

This multicenter, randomized, double-blind clinical trial was undertaken to compare the intraocular pressure (IOP)-lowering efficacy and safety of topical bimatoprost 0.03% with that of latanoprost 0.005% for the treatment of patients with normal-tension glaucoma. After washout of all ocular hypotensive medications, patients with normal-tension glaucoma (n=60) were randomly assigned to oncedaily bimatoprost 0.03% or latanoprost 0.005% for 3 mo. Diurnal IOP measurements were taken at each study visit. Primary outcome measures consisted of mean change from baseline IOP (8 AM, Noon, 4 PM) and change in visual field. Secondary measures included mean IOP, ophthalmologic examination findings, results of clinical evaluation, and adverse events. Mean change from baseline IOP at each study visit was statistically significant at all diurnal measurements for patients taking bimatoprost and for those taking latanoprost (P<.001). The 8 AM mean change from baseline IOP measurement showed a significant between-group difference (P< or =.033) in favor of bimatoprost at both follow-up visits. After 3 mo of treatment, mean IOP reductions from baseline ranged from 2.8 to 3.8 mm Hg (17.5%-21.6%) with bimatoprost and from 2.1 to 2.6 mm Hg (12.7%-16.2%) with latanoprost. Overall mean reduction in IOP after 3 mo of treatment was 3.4 mm Hg (19.9% rpar; with bimatoprost and 2.3 mm Hg (14.6%) with latanoprost (P=.035). No significant between-group differences were observed in incidence of adverse events, clinical success, or demographic variables. Bimatoprost was found to be more effective than latanoprost in lowering IOP in the patient with normal-tension glaucoma. Both drugs were efficacious and well tolerated.

Location of glaucoma drainage devices relative to the optic nerve

BACKGROUND

Limited data are available to guide optimal positioning of glaucoma drainage devices (GDD) in relation to the limbus and optic nerve. The authors aim to provide guidelines for appropriate and safe GDD implantation.

METHOD

The optimal positioning of five different GDD were evaluated using necropsy eyes of varying axial lengths. The dependent variable that was measured was the maximum distance that a GDD could be placed posterior to the limbus while remaining 2 mm away from the optic nerve.

RESULTS

The average maximum distance posterior to the limbus of the anterior plate edge ranged between 9.0-15.0 mm in the superotemporal quadrant for the GDD tested. The distances for superonasal, inferonasal, and inferotemporal quadrants ranged between 8.0-14.0 mm, 9.0-14.0 mm, and 11.0-17.0 mm, respectively. The Molteno device could be placed most posteriorly while remaining 2 mm away from the nerve. The Ahmed FP7 and S2 were the least amenable to posterior placement before encroaching on the 2 mm limit.

CONCLUSION

The maximum distance that a GDD can be placed posterior to the limbus, before encroachment around the optic nerve, varies between different devices and quadrants of placement. Taking a measurement of the exact distance of the plate from the limbus during GDD surgery is recommended.

Needle bleb revision of encapsulated filtering bleb with bevacizumab

The utility of needle bleb revision with bevacizumab in a patient with a failing bleb following trabeculectomy is explored. The patient had previously failed needle bleb revision with mitomycin C. After needling and injection of 1 mg of bevacizumab, the bleb was noted to be more diffuse with a decrease in surface neovascularization. Bevacizumab may be an effective medication for rescuing failing filtering blebs that exhibit neovascularization.

Intravitreal bevacizumab in a patient with neovascular glaucoma

The utility of intravitreal bevacizumab injection in a patient with neovascular glaucoma following central retinal vein occlusion is explored. Bevacizumab (1 mg in 0.04 mL) was used after failed intraocular pressure (IOP) control with transscleral cyclophotocoagulation and panretinal photocoagulation. IOP improved within 2 days and the patient experienced marked improvement in comfort. Bevacizumab may be an effective medication for the treatment of neovascular glaucoma.

A new quality assessment parameter for optical coherence tomography

AIM

To create a new, automated method of evaluating the quality of optical coherence tomography (OCT) images and to compare its image quality discriminating ability with the quality assessment parameters signal to noise ratio (SNR) and signal strength (SS).

METHODS

A new OCT image quality assessment parameter, quality index (QI), was created. OCT images (linear macular scan, peripapillary circular scan, and optic nerve head scan) were analysed using the latest StratusOCT system. SNR and SS were collected for each image. QI was calculated based on image histogram information using a software program of our own design. To evaluate the performance of these parameters, the results were compared with subjective three level grading (excellent, acceptable, and poor) performed by three OCT experts.

RESULTS

63 images of 21 subjects (seven each for normal, early/moderate, and advanced glaucoma) were enrolled in this study. Subjects were selected in a consecutive and retrospective fashion from our OCT imaging database. There were significant differences in SNR, SS, and QI between excellent and poor images (p = 0.04, p = 0.002, and p<0.001, respectively, Wilcoxon test) and between acceptable and poor images (p = 0.02, p<0.001, and p<0.001, respectively). Only QI showed significant difference between excellent and acceptable images (p = 0.001). Areas under the receiver operating characteristics (ROC) curve for discrimination of poor from excellent/acceptable images were 0.68 (SNR), 0.89 (IQP), and 0.99 (QI).

CONCLUSION

A quality index such as QI may permit automated objective and quantitative assessment of OCT image quality that performs similarly to an expert human observer.

A Multicenter, Retrospective Pilot Study of Resource Use and Costs Associated With Severity of Disease in Glaucoma

OBJECTIVE

To examine resource consumption and the direct costs of treating glaucoma at different disease severity levels.

DESIGN

Observational, retrospective cohort study based on medical record review.

PARTICIPANTS

One hundred fifty-one records of patients with primary open-angle or normal-tension glaucoma, glaucoma suspect, or ocular hypertension (age > or =18 years) were randomly selected from 12 sites in the United States and stratified according to severity based on International Classification of Diseases, Ninth Revision, Clinical Modification codes. Patients had to have been followed up for a minimum of 5 years. Patients with concomitant ocular disease likely to affect glaucoma treatment-related resource consumption were excluded.

METHODS

Glaucoma severity was assessed and assigned using a 6-stage glaucoma staging system, modified from the Bascom Palmer (Hodapp-Anderson-Parrish) system. Clinical and resource use data were collected from the medical record review. Resource consumption for low-vision care and vision rehabilitation was estimated for patients with end-stage disease based on specialist surveys. For each stage of disease, publicly available economic data were then applied to assign resource valuation and estimate patient-level direct costs from the payer perspective.

MAIN OUTCOME MEASURES

Average annual resource use and estimated total annual direct cost of treatment were calculated at the patient level and stratified by stage of disease. Direct costs by specific resource types, including ophthalmology visits, glaucoma surgeries, medications, visual field examinations, and other glaucoma services, were also assessed.

RESULTS

Direct ophthalmology-related resource use, including ophthalmology visits, glaucoma surgeries, and medication use, increased as disease severity worsened. Average direct cost of treatment ranged from $623 per patient per year for glaucoma suspects or patients with early-stage disease to $2511 per patient per year for patients with end-stage disease. Medication costs composed the largest proportion of total direct cost for all stages of disease (range, 24%-61%).

CONCLUSIONS

The study results suggest that resource use and direct cost of glaucoma management increase with worsening disease severity. Based on these findings, a glaucoma treatment that delays the progression of disease could have the potential to significantly reduce the health economic burden of this chronic disease over many years.

Categorizing the stage of glaucoma from pre-diagnosis to end-stage disease

PURPOSE

To provide a reliable, comprehensive staging system to assess glaucoma stage in the absence of an universally accepted glaucoma staging system (GSS) on the basis of visual field results.

DESIGN

Literature review and GSS adaptation.

METHODS

After a review of published GSSs was conducted, the Bascom Palmer (Hodapp-Anderson-Parrish) GSS was selected as an appropriate platform for a retrospective GSS on the basis of visual fields. The system was modified by a panel of glaucoma specialists, and additional modifications were made after pilot testing to cover the full range of disease progression, from preglaucoma diagnosis to complete blindness; the ordered stages reflect the typical progression of glaucoma.

RESULTS

The GSS is comprised of six ordered stages and is on the basis of the Humphrey visual field. The completed GSS was validated by reviewing patient charts from 12 US glaucoma centers.

CONCLUSIONS

The GSS allows accurate staging of 100% of glaucoma on the basis of visual fields and other data, enabling evaluation of disease progression and resource utilization at various glaucoma stages. Additionally, treatment costs may be assigned to determine cost-effectiveness of treatment. Research utilizing the GSS has found that cost of care increases with increasing disease severity. The GSS may be used as the basis for creating treatment guidelines, which have the potential to delay glaucoma progression and lower treatment costs.

Cost-effectiveness of monotherapy treatment of glaucoma and ocular hypertension with the lipid class of medications

PURPOSE

Cost-effectiveness evaluation of monotherapy with the newer lipid class of intraocular pressure (IOP)-lowering medications in glaucoma and ocular hypertension.

DESIGN

Retrospective pharmacoeconomic analysis.

METHODS

Analysis included all published studies measuring IOP reduction from untreated baseline with once-daily bimatoprost (Lumigan), latanoprost (Xalatan), or travoprost (Travatan) monotherapy in patients with elevated IOP. Percentage IOP reduction at the final study visit was calculated using the early morning IOP measurement to control for diurnal variation in IOP. Patient-weighted average percentage IOP reductions were computed for each medication. Cost per 2.5-ml bottle was determined using PriceAlert 2005 (February). Cost-effectiveness was defined as monthly cost of medication per patient-weighted average 1% reduction in IOP.

RESULTS

Studies included 951 bimatoprost, 1598 latanoprost, and 765 travoprost patients. The AWP in February, 2005 for a 2.5-ml bottle was 62.10 dollars for bimatoprost, 61.29 dollars for latanoprost, and 62.19 dollars for travoprost. Patient-weighted average IOP reduction was 32.4% for bimatoprost, 29.6% for latanoprost, and 29.0% for travoprost. Calculated cost-effectiveness was 1.92 dollars for bimatoprost, 2.07 dollars for latanoprost, and 2.14 dollars for travoprost. Incremental cost-effectiveness ratio (ICER) analysis showed an incremental cost of 0.29 dollars for each additional 1% IOP reduction provided by bimatoprost over latanoprost. The rank order of the cost-effectiveness of the drugs (bimatoprost > latanoprost > travoprost) was robust in sensitivity analyses to cost and efficacy.

CONCLUSIONS

On the basis of AWP and patient-weighted average percentage IOP reduction in published studies, bimatoprost had the most favorable cost-effectiveness among the drugs compared. Cost-effectiveness should be considered along with traditional clinical safety and efficacy measures to make individual and group healthcare decisions.

Optical coherence tomography machine learning classifiers for glaucoma detection: a preliminary study

PURPOSE

Machine-learning classifiers are trained computerized systems with the ability to detect the relationship between multiple input parameters and a diagnosis. The present study investigated whether the use of machine-learning classifiers improves optical coherence tomography (OCT) glaucoma detection.

METHODS

Forty-seven patients with glaucoma (47 eyes) and 42 healthy subjects (42 eyes) were included in this cross-sectional study. Of the glaucoma patients, 27 had early disease (visual field mean deviation [MD] > or = -6 dB) and 20 had advanced glaucoma (MD < -6 dB). Machine-learning classifiers were trained to discriminate between glaucomatous and healthy eyes using parameters derived from OCT output. The classifiers were trained with all 38 parameters as well as with only 8 parameters that correlated best with the visual field MD. Five classifiers were tested: linear discriminant analysis, support vector machine, recursive partitioning and regression tree, generalized linear model, and generalized additive model. For the last two classifiers, a backward feature selection was used to find the minimal number of parameters that resulted in the best and most simple prediction. The cross-validated receiver operating characteristic (ROC) curve and accuracies were calculated.

RESULTS

The largest area under the ROC curve (AROC) for glaucoma detection was achieved with the support vector machine using eight parameters (0.981). The sensitivity at 80% and 95% specificity was 97.9% and 92.5%, respectively. This classifier also performed best when judged by cross-validated accuracy (0.966). The best classification between early glaucoma and advanced glaucoma was obtained with the generalized additive model using only three parameters (AROC = 0.854).

CONCLUSIONS

Automated machine classifiers of OCT data might be useful for enhancing the utility of this technology for detecting glaucomatous abnormality.

Comparison of Corneal Surface Effects of Gatifloxacin and Moxifloxacin Using Intensive and Prolonged Dosing Protocols

PURPOSE

To compare the effects of the commercial formulations of moxifloxacin and gatifloxacin on rabbit corneal epithelium using two dosing protocols: high-frequency dosing for bacterial keratitis and cataract surgery prophylaxis.

METHODS

Forty eyes of 20 New Zealand white rabbits were randomized to receive topical gatifloxacin, topical moxifloxacin, or no drops as controls. Eighteen eyes received 1 drop of antibiotic every 5 minutes for 15 minutes followed by 1 drop every 15 minutes for 4 hours. Twelve eyes received topical gatifloxacin or topical moxifloxacin 4 times a day for 10 days. Rabbits were euthanized, eyes enucleated, and the corneas separated, washed, and fixed; scanning electron microscopy was performed. Photomicrographs of three separate areas from the corneal apex were taken at x1200 and x3000 for each cornea. Two masked, experienced examiners then graded the corneal epithelial damage.

RESULTS

In the high-frequency dosing group, mean corneal damage score for eyes treated with gatifloxacin was 1.593, that for moxifloxacin was 1.407, and control was 1.000. No statistically significant difference was found between gatifloxacin and moxifloxacin (P = 0.41), gatifloxacin and control (P = 0.14), or moxifloxacin and control (P = 0.23). In the cataract surgery prophylaxis group, mean corneal damage scores for eyes treated with gatifloxacin was 1.167, that for moxifloxacin was 1.368, and control was 1.000. No statistically significant difference was found between gatifloxacin and moxifloxacin (P = 0.23), gatifloxacin and control (P = 0.08), or moxifloxacin and control (P = 0.23).

CONCLUSION

Despite differences in formulations, with short-term dosing neither gatifloxacin nor moxifloxacin appears to be toxic to the corneal epithelium in this rabbit model.

Comparative penetration of moxifloxacin and gatifloxacin in rabbit aqueous humor after topical dosing

PURPOSE

To evaluate the aqueous penetration of the fourth-generation fluoroquinolones moxifloxacin and gatifloxacin.

SETTING

University of Arizona, Tucson, Arizona, USA.

METHODS

Forty eyes of 20 New Zealand white rabbits were divided into 2 experimental groups. In Experiment I rabbits (20 eyes), a commercial preparation of topical gatifloxacin 0.3% was administered to 9 eyes and moxifloxacin 0.5% to 9 eyes; 2 eyes served as a control. Eyes were dosed according to a keratitis protocol; ie, every 15 minutes for 4 hours. The aqueous humor was sampled 10 minutes after the last dose. Experiment II rabbits (20 eyes) were dosed according to a cataract prophylaxis protocol; ie, 4 times a day for 10 days. The aqueous humor was sampled 1 hour after the last dose of antibiotic in 12 eyes and 24 hours after the last dose in 8 eyes. High-performance liquid chromatography was used to determine the fluoroquinolone concentration.

RESULTS

In the keratitis dosing protocol, the mean concentration of moxifloxacin in the aqueous (n=9) was 11.057 microg/mL (range 7.66 to 18.87 microg/mL), which was significantly higher than the mean concentration of gatifloxacin (n=8) (7.570 microg/mL [range 4.75 to 10.86 microg/mL]) (P=.030). In the cataract prophylaxis dosing protocol, the mean aqueous concentration of moxifloxacin (n=6) was 1.745 microg/mL (range 0.92 to 3.87 mg/mL). The mean concentration of gatifloxacin (n=6) was 1.207 microg/mL (range 0.44 to 2.44 microg/mL). The difference was not statistically significant (P=.359).

CONCLUSIONS

Higher mean levels (x1.46) of aqueous penetration were achieved with moxifloxacin than with gatifloxacin in the keratitis-dosing model. There was no statistically significant difference between the 2 drugs in the cataract prophylaxis dosing model. Both antibiotics had aqueous levels in excess of the minimum inhibitory concentration for most pathogenic organisms in both models.

Bimatoprost versus latanoprost in lowering intraocular pressure in glaucoma and ocular hypertension: results from parallel-group comparison trials

This review evaluated the clinical evidence of the comparative efficacy and safety of bimatoprost and latanoprost in lowering intraocular pressure (IOP) in patients with glaucoma and ocular hypertension. Four head-to-head, randomized, and controlled clinical trials of bimatoprost and latanoprost with treatment periods ranging from 1 to 6 months were identified from searches of the MEDLINE database through February 2004. According to a review and comparison of the results, bimatoprost, when compared with latanoprost, was associated with greater mean reductions in IOP, greater mean increases in the percentage of patients demonstrating target IOP, and greater response rates. The differences between drugs were not always statistically significant. Overall, the between-group differences in mean IOP ranged from 0 to 1.5 mm Hg. In 92% of the IOP measurements, the mean IOP was lower among patients given bimatoprost than among those given latanoprost; in the remaining 8%, the IOP reduction was equal. Transient, mild conjunctival hyperemia was the most frequently reported adverse effect associated with either drug, but it occurred more frequently with bimatoprost. Overall, both drugs were well tolerated. As a 1-mm Hg change in IOP has been shown to reduce the risk of progression in patients with glaucoma (according to the Early Manifest Glaucoma Trial), the greater efficacy demonstrated by bimatoprost in lowering IOP may be clinically significant.