Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Timothy L. Comstock is active.

Publication


Featured researches published by Timothy L. Comstock.


Archives of Ophthalmology | 2008

Treatment of posterior uveitis with a fluocinolone acetonide implant: three-year clinical trial results.

David Callanan; Glenn J. Jaffe; Daniel F. Martin; Pearson Pa; Timothy L. Comstock

OBJECTIVES To evaluate the safety and efficacy of 0.59-mg and 2.1-mg fluocinolone acetonide (FA) intravitreous implants in noninfectious posterior uveitis. DESIGN A 3-year, multicenter, randomized, historically controlled trial of the 0.59-mg FA intravitreous implant in 110 patients and the 2.1-mg FA intravitreous implant in 168 patients. MAIN OUTCOME MEASURES Recurrence rate, vision, and complications. RESULTS Uveitis recurrence was reduced in implanted eyes from 62% (during the 1-year preimplantation period) to 4%, 10%, and 20% during the 1-, 2-, and 3-year postimplantation periods, respectively, for the 0.59-mg dose group (P < .01) and from 58% to 7%, 17%, and 41%, respectively, for the 2.1-mg dose group (P < .01). More implanted eyes than nonimplanted eyes had improved visual acuity (P < .01). Implanted eyes had higher incidences of intraocular pressure elevation (> or = 10 mm Hg) than nonimplanted eyes (P < .01), and glaucoma surgery was required in 40% of implanted eyes vs 2% of nonimplanted eyes (P < .01). Cataracts were extracted in 93% of phakic implanted eyes vs 20% of phakic nonimplanted eyes (P < .01). CONCLUSIONS The FA implant significantly reduced uveitis recurrence and improved or stabilized visual acuity in subjects with noninfectious posterior uveitis. Most subjects required cataract extraction, and a significant proportion required intraocular pressure-lowering surgery. APPLICATION TO CLINICAL PRACTICE The FA implant provides an alternative therapy for prolonged control of inflammation in noninfectious posterior uveitis. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00407082.


Ophthalmology | 2011

Fluocinolone Acetonide Intravitreal Implant for Diabetic Macular Edema: A 3-Year Multicenter, Randomized, Controlled Clinical Trial

P. Andrew Pearson; Timothy L. Comstock; Michael Ip; David Callanan; Lawrence S. Morse; Paul Ashton; Brian Levy; Eric S. Mann; Dean Eliott

PURPOSE We studied the 3-year efficacy and safety results of a 4-year study evaluating fluocinolone acetonide (FA) intravitreal implants in eyes with persistent or recurrent diabetic macular edema (DME). DESIGN Prospective, evaluator-masked, controlled, multicenter clinical trial. PARTICIPANTS We included 196 eyes with refractory DME. METHODS Patients were randomized 2:1 to receive 0.59-mg FA implant (n = 127) or standard of care (SOC additional laser or observation; n = 69). The implant was inserted through a pars plana incision. Visits were scheduled on day 2, weeks 1, 3, 6, 12, and 26, and thereafter every 13 weeks through 3 years postimplantation. MAIN OUTCOME MEASURES The primary efficacy outcome was ≥15-letter improvement in visual acuity (VA) at 6 months. Secondary outcomes included resolution of macular retinal thickening and Diabetic Retinopathy Severity Score (DRSS). Safety measures included incidence of adverse events (AEs). RESULTS Overall, VA improved ≥3 lines in 16.8% of implanted eyes at 6 months (P=0.0012; SOC, 1.4%); in 16.4% at 1 year (P=0.1191; SOC, 8.1%); in 31.8% at 2 years (P=0.0016; SOC, 9.3%); and in 31.1% at 3 years (P=0.1566; SOC, 20.0%). The number of implanted eyes with no evidence of retinal thickening at the center of the macula was higher than SOC eyes at 6 months (P<0.0001), 1 year (P<0.0001; 72% vs 22%), 2 years (P=0.016), and 3 years (P=0.861). A higher rate of improvement and lower rate of decline in DRSS occurred in the implanted group versus the SOC group at 6 months (P=0.0006), 1 year (P=0.0016), 2 years (P=0.012), and 3 years (P=0.0207). Intraocular pressure (IOP) ≥30 mmHg was recorded in 61.4% of implanted eyes (SOC, 5.8%) at any time and 33.8% required surgery for ocular hypertension by 4 years. Of implanted phakic eyes, 91% (SOC, 20%) had cataract extraction by 4 years. CONCLUSIONS The FA intravitreal implant met the primary and secondary outcomes, with significantly improved VA and DRSS and reduced DME. The most common AEs included cataract progression and elevated IOP. The 0.59-mg FA intravitreal implant may be an effective treatment for eyes with persistent or recurrent DME. FINANCIAL DISCLOSURE(S) Proprietary or commercial disclosure may be found after the references.


Ophthalmology | 2002

A 1-year prospective clinical trial of balafilcon a (purevision) silicone-hydrogel contact lenses used on a 30-day continuous wear schedule

Noel A. Brennan; M.-L. Chantal Coles; Timothy L. Comstock; Brian Levy

PURPOSE To evaluate silicone-hydrogel balafilcon A (PureVision, Bausch & Lomb Inc., Rochester, NY) contact lenses worn on a 30-day continuous wear basis when compared with a traditional hydrogel (Acuvue, Vistakon, Johnson and Johnson Vision Products, Inc., Jacksonville, FL) worn on a 7-day extended wear schedule. DESIGN Prospective, comparative, paired-eye, interventional, multicenter clinical trial. PARTICIPANTS Two hundred twelve ametropes with no significant ocular pathology. METHODS Subjects with normal ocular health who conformed to a set of standard criteria were monitored at seven different sites around the globe. Subjects wore both study lenses simultaneously, one on each eye. Lenses were assigned to right and left eyes according to a randomized schedule. The silicone hydrogel was removed and replaced every month and the traditional hydrogel was removed every 7 days and replaced at 14-day intervals. Subjects were followed for up to 1 year with discontinuation on indication divided between lens-related causes, unrelated factors, and loss to follow-up. MAIN OUTCOME MEASURES Discontinuations, symptoms, vision, lens fit, lens surface assessment, slit-lamp assessment, and patient preferences. RESULTS One hundred twenty three subjects completed the 12-month wearing period. There were no vision-threatening events with either lens type. The silicone-hydrogel lenses showed statistically superior performance in physiologic terms with regard to epithelial microcysts, striae, corneal staining, limbal injection, and bulbar injection. Inflammatory reactions, such as corneal infiltrates and tarsal conjunctival abnormalities occurred at similar rates between the lens types. Visible deposition and postlens debris with associated transient corneal indentation were significantly lower with the traditional hydrogel material at specific time points in the study. Visual acuity was comparable with the two lens types. Subjects rated the silicone-hydrogel material as preferable on subjective scales of dryness, comfort, and lens handling. Overall subjective performance was rated superior with the silicone-hydrogel material. CONCLUSIONS The high oxygen performance of the silicone-hydrogel lenses provides a superior physiologic environment compared with a traditional hydrogel material during continuous wear. Despite the slightly higher levels of visible deposit on the silicone-hydrogels, superior subjective responses suggest that the plasma coating technology on these lenses is effective in providing comfortable lens wear. The results look promising for the success of silicone-hydrogels as the material of choice for continuous wear contact lenses.


Ophthalmology | 2010

Evaluation of an Intravitreal Fluocinolone Acetonide Implant versus Standard Systemic Therapy in Noninfectious Posterior Uveitis

Carlos Pavesio; Manfred Zierhut; Khaled Bairi; Timothy L. Comstock; Dale W. Usner

PURPOSE To evaluate the safety and efficacy of an intravitreal fluocinolone acetonide (FA) implant compared with standard therapy in subjects with noninfectious posterior uveitis (NIPU). DESIGN Randomized, controlled, phase 2b/3, open-label, multicenter superiority trial. PARTICIPANTS Subjects with unilateral or bilateral NIPU. METHODS One hundred forty subjects received either a 0.59-mg FA intravitreal implant (n = 66) or standard of care (SOC; n = 74) with either systemic prednisolone or equivalent corticosteroid as monotherapy (> or =0.2 mg/kg daily) or, if judged necessary by the investigator, combination therapy with an immunosuppressive agent plus a lower dose of prednisolone or equivalent corticosteroid (> or =0.1 mg/kg daily). MAIN OUTCOME MEASURES Time to first recurrence of uveitis. RESULTS Eyes that received the FA intravitreal implant experienced delayed onset of observed recurrence of uveitis (P<0.01) and a lower rate of recurrence of uveitis (18.2% vs. 63.5%; P< or =0.01) compared with SOC study eyes. Adverse events frequently observed in implanted eyes included elevated intraocular pressure (IOP) requiring IOP-lowering surgery (occurring in 21.2% of implanted eyes) and cataracts requiring extraction (occurring in 87.8% of phakic implanted eyes). No treatment-related nonocular adverse events were observed in the implant group, whereas such events occurred in 25.7% of subjects in the SOC group. CONCLUSIONS The FA intravitreal implant provided better control of inflammation in patients with uveitis compared with systemic therapy. Intraocular pressure and lens clarity of implanted eyes need close monitoring in patients receiving the FA intravitreal implant.


Clinical Therapeutics | 2009

Besifloxacin ophthalmic suspension 0.6% in patients with bacterial conjunctivitis: A multicenter, prospective, randomized, double-masked, vehicle-controlled, 5-day efficacy and safety study

Paul Karpecki; Michael DePaolis; Judy A. Hunter; Eric M. White; Lee Rigel; Lynne Brunner; Dale W. Usner; Michael R. Paterno; Timothy L. Comstock

BACKGROUND Besifloxacin ophthalmic suspension 0.6% is a new topical fluoroquinolone for the treatment of bacterial conjunctivitis. Besifloxacin has potent in vitro activity against a broad spectrum of ocular pathogens, including drug-resistant strains. OBJECTIVE The primary objective of this study was to compare the clinical and microbiologic efficacy of besifloxacin ophthalmic suspension 0.6% with that of vehicle (the formulation without besifloxacin) in the treatment of bacterial conjunctivitis. METHODS This was a multicenter, prospective, randomized, double-masked, vehicle-controlled, parallel-group study in patients with acute bacterial conjunctivitis. Patients received either topical besifloxacin ophthalmic suspension or vehicle administered 3 times daily for 5 days. At study entry and on days 4 and 8 (visits 2 and 3), a clinical assessment of ocular signs and symptoms was performed in both eyes, as well as pinhole visual acuity testing, biomicroscopy, and culture of the infected eye(s). An ophthalmoscopic examination was performed at study entry and on day 8. The primary efficacy outcome measures were clinical resolution and eradication of the baseline bacterial infection on day 8 in culture-confirmed patients. The safety evaluation included adverse events, changes in visual acuity, and biomicroscopy and ophthalmoscopy findings in all patients who received at least 1 dose of active treatment or vehicle. RESULTS The safety population consisted of 269 patients (mean [SD] age, 34.2 [22.3] years; 60.2% female; 82.5% white) with acute bacterial conjunctivitis. The culture-confirmed intent-to-treat population consisted of 118 patients (60 besifloxacin ophthalmic suspension, 58 vehicle). Significantly more patients receiving besifloxacin ophthalmic suspension than vehicle had clinical resolution of the baseline infection at visit 3 (44/60 [73.3%] vs 25/58 [43.1%], respectively; P < 0.001). Rates of bacterial eradication also were significantly greater with besifloxacin ophthalmic suspension compared with vehicle at visit 3 (53/60 [88.3%] vs35/58 [60.3%]; P < 0.001). The cumulative frequency of adverse events did not differ significantly between the 2 groups (69/137 [50.4%] and 70/132 [53.0%]). The most common ocular adverse events were eye pain (20/190 treated eyes [10.5%] and 13/188 [6.9%]), blurred vision (20/190 [10.5%] and 22/188 [11.7%]), and eye irritation (14/190 [7.4%] and 23/188 [12.2%]); these events were of mild or moderate severity. Changes in visual acuity and treatment-emergent events observed on biomicroscopy and direct ophthalmoscopy also were comparable between treatment groups. CONCLUSION Besifloxacin ophthalmic suspension 0.6% given 3 times daily for 5 days was both efficacious and well tolerated compared with vehicle in the treatment of these patients with bacterial conjunctivitis. ClinicalTrials.gov Identifier: NCT00622908.


Current Medical Research and Opinion | 2009

Phase III efficacy and safety study of besifloxacin ophthalmic suspension 0.6% in the treatment of bacterial conjunctivitis

Michael Tepedino; Warren H. Heller; Dale W. Usner; Lynne Brunner; Timothy W. Morris; Wolfgang Haas; Michael R. Paterno; Timothy L. Comstock

ABSTRACT Objective: To compare the clinical and antimicrobial efficacy of besifloxacin ophthalmic suspension 0.6% with that of vehicle in the treatment of bacterial conjunctivitis. Research design and methods: This was a randomized, multicenter, double-masked, vehicle-controlled study. A total of 957 patients aged 1 year and older with bacterial conjunctivitis were randomized to treatment with besifloxacin ophthalmic suspension 0.6% or vehicle applied topically three times daily for 5 days. Main outcome measures: Primary endpoints were clinical resolution and microbial eradication of baseline bacterial infection at Visit 2 (Day 5 ± 1). Secondary endpoints included clinical resolution and microbial eradication at Visit 3 (Day 8 or 9), individual clinical outcomes at follow-up visits, and safety. Clinical trial registration: NCT number, NCT00347932. Results: Three hundred and ninety patients had culture-confirmed bacterial conjunctivitis. Clinical resolution and microbial eradication were significantly greater with besifloxacin ophthalmic suspension than with vehicle at Visit 2 (45.2% vs. 33.0%, p = 0.0084; and 91.5% vs. 59.7%, p < 0.0001, respectively) and Visit 3 (84.4% vs. 69.1%, p = 0.0011; and 88.4% vs. 71.7%, p < 0.0001, respectively). Results for secondary endpoints of individual clinical outcomes were consistent with primary endpoints. Fewer eyes receiving besifloxacin ophthalmic suspension experienced adverse events than those receiving vehicle (9.2% vs. 13.9%; p = 0.0047). Conclusions: Besifloxacin ophthalmic suspension produces clinical resolution and microbial eradication rates significantly better than vehicle and is safe for the treatment of bacterial conjunctivitis. Limitations: A limitation of this study is the lack of a non-treatment control group.


Ophthalmology | 2009

Efficacy and Safety of Besifloxacin Ophthalmic Suspension 0.6% Compared with Moxifloxacin Ophthalmic Solution 0.5% for Treating Bacterial Conjunctivitis

Marguerite B. McDonald; Eugene E. Protzko; Lynne Brunner; Timothy W. Morris; Wolfgang Haas; Michael R. Paterno; Timothy L. Comstock; Dale W. Usner

OBJECTIVE To compare the clinical and antimicrobial efficacy of besifloxacin ophthalmic suspension 0.6% with that of moxifloxacin ophthalmic solution 0.5% for the treatment of bacterial conjunctivitis. DESIGN Multicenter, randomized, double-masked, parallel-group, active-controlled, noninferiority study. PARTICIPANTS Patients 1 year of age or older with clinical manifestations of bacterial conjunctivitis. METHODS Eligible patients were randomized to either besifloxacin suspension or moxifloxacin solution, instilled in the infected eye(s) 3 times daily for 5 days, and participated in study visits on days 1, 5 (+/-1 day), and 8 (+1 day). Assessments included clinical evaluation of signs and symptoms, visual acuity, biomicroscopy, and culture of the infected eye(s) at each visit, as well as direct ophthalmoscopy on days 1 and 8. MAIN OUTCOME MEASURES The primary efficacy end points were clinical resolution and microbial eradication of baseline bacterial infection on day 5 in patients with culture-confirmed bacterial conjunctivitis. Secondary end points included clinical resolution and microbial eradication on day 8, individual clinical outcomes, microbial and clinical outcomes by bacterial species, and safety. RESULTS A total of 1161 patients (533 with culture-confirmed bacterial conjunctivitis) were randomized. Based on the 95% confidence interval (CI) of the difference, besifloxacin was noninferior to moxifloxacin for clinical resolution on day 5 (58.3% vs. 59.4%, respectively; 95% CI, -9.48 to 7.29) and day 8 (84.5% vs. 84.0%, respectively, 95% CI, -5.6% to 6.75%) and for microbial eradication on day 5 (93.3% vs. 91.1%, respectively, 95% CI, -2.44 to 6.74) and day 8 (87.3% vs. 84.7%; 95% CI, -3.32 to 8.53). There was no statistically significant difference between the 2 treatment groups for either efficacy end points on days 5 or 8 (P>0.05). Besifloxacin and moxifloxacin were well tolerated. The cumulative frequency of ocular adverse events was similar between treatments (12% and 14% with besifloxacin and moxifloxacin, respectively). However, eye irritation occurred more often in moxifloxacin-treated eyes (0.3% for besifloxacin vs. 1.4% for moxifloxacin; P = 0.0201). CONCLUSIONS Besifloxacin ophthalmic suspension was non inferior to moxifloxacin ophthalmic suspension and provided similar safety and efficacy (clinical and microbiological) outcomes when used for the treatment of bacterial conjunctivitis. FINANCIAL DISCLOSURE(S) Proprietary or commercial disclosure may be found after the references.


Journal of Ocular Pharmacology and Therapeutics | 2009

Ocular Pharmacokinetics of Besifloxacin Following Topical Administration to Rabbits, Monkeys, and Humans

Joel W. Proksch; Camille P. Granvil; Raphaele Siou-Mermet; Timothy L. Comstock; Michael R. Paterno; Keith W. Ward

PURPOSE Studies were conducted to evaluate the ocular penetration and systemic exposure to besifloxacin, a fluoroquinolone antibiotic, following topical ocular administration to animals and humans. METHODS Besifloxacin ophthalmic suspension (0.6%) was administered as a topical ocular instillation to pigmented rabbits, cynomolgus monkeys, and human subjects. At predetermined intervals after dosing, samples of ocular tissues and plasma were collected and analyzed for besifloxacin levels using HPLC/MS/MS methods. RESULTS Besifloxacin demonstrated good ocular penetration in rabbits and monkeys, with rapid absorption and sustained concentrations observed in anterior ocular tissues through 24 h after a single administration. Maximum besifloxacin concentrations in conjunctiva, cornea, and aqueous humor of monkeys were 6.43 microg/g, 2.10 microg/g, and 0.796 microg/mL, respectively, after a single topical dose, and concentrations declined in these tissues with an apparent half-life of 5-14 h. Following a single topical ocular administration to humans, the maximum besifloxacin concentration in tears was 610 microg/g with concentrations decreasing to approximately 1.6 microg/g at 24 h. The resulting pharmacokinetic parameters for besifloxacin in human tears were evaluated relative to the MIC(90) values (microg/mL) for besifloxacin against Streptococcus pneumoniae (0.125), Staphylococcus aureus (0.25), Staphylococcus epidermidis (0.5), and Haemophilus influenzae (0.06). Following a single topical administration, the C(max)/MIC(90) ratios for besifloxacin in human tears were > or =1,220, and the AUC((0-24))/MIC(90) ratios were > or =2,500 for these relevant ocular pathogens. Following repeated 3-times daily (TID) topical ocular administration to human subjects with clinically diagnosed bacterial conjunctivitis, maximum besifloxacin concentrations in plasma were less than 0.5 ng/mL, on average. CONCLUSIONS Taken together, the results of the current investigation provide a PK/PD-based rationale that supports the use of besifloxacin for the safe and effective treatment of ocular infections.


Cornea | 2008

Effects of loteprednol/tobramycin versus dexamethasone/tobramycin on intraocular pressure in healthy volunteers.

Edward J. Holland; Jimmy D. Bartlett; Michael R. Paterno; Dale W. Usner; Timothy L. Comstock

Purpose: To compare the steroid-induced intraocular pressure (IOP) and other ocular adverse effects of loteprednol etabonate 0.5% and tobramycin 0.3% ophthalmic suspension with those of dexamethasone 0.1% and tobramycin 0.3% ophthalmic suspension. Methods: Three hundred six healthy volunteers received either loteprednol etabonate/tobramycin (n = 156) or dexamethasone/tobramycin (n = 150) at 4-hour intervals 4 times a day in both eyes for 28 days in this randomized, double-masked, multicenter, parallel-group trial. IOP, visual acuity (VA), and ocular health were assessed at all study visits (days 1, 3, 8, 15, 22, and 29), whereas undilated direct ophthalmoscopy was completed at the baseline and final visits. Adverse events (AEs) were assessed at all follow-up visits. Results: The number of subjects experiencing IOP increases of ≥10 mm Hg from baseline at any study visit for the loteprednol etabonate/tobramycin group (3 subjects, 1.95%) was significantly lower than that for the dexamethasone/tobramycin group (11 subjects, 7.48%; P = 0.0280), as were mean changes from baseline IOP (P < 0.05 at all visits). The lowest VA recorded for any subject at any visit was 20/40 and reductions of ≥2 lines at any visit were observed in 14 (4.55%) eyes for loteprednol etabonate/tobramycin and in 23 (7.82%) eyes for dexamethasone/tobramycin (P = 0.1257). Both treatments were well tolerated. Conclusions: Loteprednol/tobramycin was significantly less likely to produce elevations in IOP than was dexamethasone/tobramycin in healthy subjects treated for 28 days. Both loteprednol etabonate/tobramycin and dexamethasone/tobramycin were well tolerated with low risks for systemic AEs and ocular AEs other than elevation in IOP for dexamethasone/tobramycin.


International Journal of Inflammation | 2012

Advances in Corticosteroid Therapy for Ocular Inflammation: Loteprednol Etabonate

Timothy L. Comstock; Heleen H DeCory

Topical corticosteroids are effective in reducing anterior segment inflammation but are associated with adverse drug reactions (ADRs) including elevation of intraocular pressure (IOP) and cataract formation. Retrometabolic drug design has advanced the development of new corticosteroids with improved therapeutic indices. Engineered from prednisolone, loteprednol etabonate (LE) has a 17α-chloromethyl ester, in lieu of a ketone group, and a 17β-etabonate group. LE is highly lipophilic and binds with high affinity to the glucocorticoid receptor; any unbound LE is metabolized to inactive metabolites. LE has been studied in several anterior segment inflammatory conditions (giant papillary conjunctivitis, allergic conjunctivitis, anterior uveitis, and keratoconjunctivitis sicca), and in postoperative ocular inflammation and pain. Combined with tobramycin, it is effective in blepharokeratoconjunctivitis. Elevations in IOP are infrequent with LE, and the absence of a C-20 ketone precludes formation of Schiff base intermediates with lens proteins, a common first step implicated in cataract formation with ketone steroids.

Collaboration


Dive into the Timothy L. Comstock's collaboration.

Top Co-Authors

Avatar

David Callanan

University of Texas Southwestern Medical Center

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Researchain Logo
Decentralizing Knowledge