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Dive into the research topics where Christopher J. Dickens is active.

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Featured researches published by Christopher J. Dickens.


Ophthalmology | 1992

Intraocular Pressure Reduction in Normal-tension Glaucoma Patients

Michael Schulzer; P.J. Airaksinen; Wallace L.M. Alward; Marcel Amyot; Douglas R. Anderson; Gordon Balazsi; P. Blondeau; L.F. Cashwell; J. Cohen; D. Desjardins; Christopher J. Dickens; Gordon R. Douglas; Stephen M. Drance; F. Feldman; H.C. Geijssen; A. Grajewski; Erik L. Greve; John Hetherington; Dale K. Heuer; Elizabeth Hodapp; H. D. Hoskins; Andrew G. Iwach; Henry D. Jampel; Oscar Kasner; Yoshiaki Kitazawa; R. Komulainen; R. Z. Levene; Jeffrey M. Liebmann; Frederick S Mikelberg; R. Mills

BACKGROUND In a collaborative study, patients with untreated normal-tension glaucoma were randomly assigned to a marked intraocular pressure reduction group or to a no therapy group. It was anticipated that medical therapy and laser trabeculoplasty would generally not achieve adequate pressure lowering and that fistulizing surgery would be required. This hypothesis was examined using current observations in the study. METHODS Patients randomized to the therapy group had a pressure reduction of at least 30% from their last prerandomization level. This was achieved within 6 months by means of fistulizing surgery or with pilocarpine and/or laser trabeculoplasty. Beta-blockers and adrenergic agonists were excluded from both eyes. RESULTS Of 30 patients with documented stable 30% pressure reduction, 17 (57%) achieved this with topical medication and/or laser trabeculoplasty: 8 with pilocarpine alone, 2 with laser trabeculoplasty alone, and 7 with laser trabeculoplasty after initial topical medication. The remaining 13 (43%) patients required a single fistulizing procedure. There was no statistically significant difference between the mean follow-up time for the nonfistulized group (533.8 +/- 437.6 days) and for the fistulized group (502.7 +/- 344.7 days). Both treatment groups had similar baseline profiles. CONCLUSION Marked pressure reduction can be achieved and maintained on a long-term basis by means other than fistulizing surgery in a large proportion of patients with untreated normal-tension glaucoma.


Ophthalmology | 1996

Trabeculectomy with Intraoperative Sponge 5-Fluorouracil

Justin S. Mora; Ngoc Nguyen; Andrew G. Iwach; Michelle M. Gaffney; John Hetherington; H. Dunbar Hoskins; Patricia C. Wong; Henry Tran; Christopher J. Dickens

PURPOSE To retrospectively assess the outcome of trabeculectomy surgery performed using intraoperative sponge 5-fluorouracil (5-FU) (50 mg/ml). METHODS Trabeculectomy with intraoperative sponge 5-FU was performed on 140 eyes of 119 patients. The reduction in intraocular pressure (IOP), the number of supplementary postoperative injections, and any treatment complications were noted. RESULTS The mean preoperative IOP was 25.7 +/- 8.6 mmHg. The mean postoperative IOP was 12.5 +/- 5.7 mmHg with a mean IOP reduction of 52 percent (P < 0.0001). One hundred twenty-one (86.4 percent) eyes required no postoperative glaucoma medications, with the mean number of glaucoma medications dropping from 2.5 +/- 1.1 before operation to 0.3 +/- 0.8 after operation (P < 0.001). One hundred five eyes received a mean of 5.3 +/- 2.7 postoperative 5-FU injections. There was no significant difference in final IOP or success rate between low- and high-risk eyes, but high-risk eyes seemed to require supplementary postoperative 5-FU. Corneal epithelial damage arose in 52 (37 percent) eyes and correlated strongly with postoperative 5-FU supplementation. CONCLUSION Intraoperative sponge 5-FU is a reasonably safe and effective adjunct to trabeculectomy surgery.


Ophthalmology | 1995

Long-term results of noncontact transscleral neodymium:YAG cyclophotocoagulation.

Christopher J. Dickens; Ngoc Nguyen; Justin S. Mora; Andrew G. Iwach; Michelle M. Gafffney; Patricia C. Wong; Henry Tran

PURPOSE To determine the long-term efficacy of noncontact transscleral neodymium:YAG (Nd: YAG) cyclophotocoagulation. METHODS A retrospective analysis was made of 167 patients (173 eyes) with intractable glaucoma treated with noncontact Nd:YAG cyclophotocoagulation between December 1987 and November 1993, reviewing the treatment parameters, complications, and pre- and posttreatment intraocular pressure (IOP). The IOP was compared using a Students t test, and the results were subjected to a Kaplan-Meier life-table analysis. Success was defined as an IOP of 22 mmHg or lower in the absence of phthisis and without having undergone any additional surgical procedures. RESULTS Mean follow-up was 30.5 +/- 22.8 months. Mean preoperative IOP was 40.0 +/- 12.9 mmHg. Mean postoperative IOP was 19.8 +/- 11.4 mmHg (P < 0.05). The mean number of treatment sessions was 1.8 +/- 1.3 (range, 1-8) with 95 eyes (55%) having only one treatment. Kaplan-Meier survival analysis showed a probability of continued success at 3 years of approximately 73% and at 5 years of 45%. Complications included loss of two or more lines of Snellen visual acuity or one or more categories in the low-vision range (40%), phthisis (6.9%), epithelial defects (1.9%), and hyphema (0.6%). CONCLUSION This study suggests that Nd:YAG transscleral cyclophotocoagulation provides a useful long-term reduction of IOP in eyes with advanced or complicated glaucoma, but there is a significant risk of visual loss associated with the procedure.


Ophthalmology | 2002

Long-term follow-up of initially successful trabeculectomy with 5-fluorouracil injections

Ricardo Suzuki; Christopher J. Dickens; Andrew G. Iwach; H. Dunbar Hoskins; John Hetherington; Richard P. Juster; Patricia C. Wong; Martha T Klufas; Clifford J Leong; Ngoc Nguyen

PURPOSE To study the long-term results (1-14 years) of trabeculectomies with 5-fluorouracil injections that were successful at 1 year. DESIGN A retrospective noncomparative case series. INTERVENTION/PARTICIPANTS: We identified 87 patients (87 eyes) who had trabeculectomies with 5-fluorouracil injections from 1984 to 1989 that were successful at 1 year and had a follow-up range of 1.0 to 14.7 years (mean, 8.1, standard deviation of 4.4 years). All patients had previously failed glaucoma surgery (66.7%), cataract surgery (47.1%), or other diagnoses making them at high risk for failure. MAIN OUTCOME MEASURES Successful control of intraocular pressure (IOP) was defined as IOP less than 21 mmHg or a reduction of 33% if preoperative pressure was less than 21 mmHg. Statistical analysis was performed using Kaplan-Meier life table analysis. RESULTS If an eye is considered successful by IOP at 1 year, the probability of successful control is 61% at 5 years, 44% at 10 years, and 41% at 14 years. CONCLUSIONS Despite successful IOP control at 1 year, trabeculectomies with 5-fluorouracil injections show a continual loss of IOP control over time.


Ophthalmology | 1996

A High Prevalence of Occludable Angles in a Vietnamese Population

Ngoc Nguyen; Justin S. Mora; Michelle M. Gaffney; Albert S. Ma; Patricia C. Wong; Andrew G. Iwach; Henry Tran; Christopher J. Dickens

PURPOSE To assess the prevalence of occludable angles in a Vietnamese population. METHODS The authors retrospectively reviewed the angle status in 482 Vietnamese patients who presented to a general ophthalmology practice. All angles were graded by a glaucoma specialist according to the Shaffer method. Patients were excluded if they had known glaucoma or narrow angles, or a history of trauma or intraocular surgery. RESULTS A total of 29.5% of all patients surveyed and 47.8% of those 55 years of age or older had grade 0 to 2 angles. In the Framingham study, 3.8% of white patients 55 years of age or older had grade 0 to 2 angles. Of the patients in our study population, 8.5% had grade 0 to 1 angles and were considered at high risk for occlusion. CONCLUSIONS Vietnamese patients have a much higher prevalence of narrow angles and a greater risk of angle-closure glaucoma than white patients.


Ophthalmology | 1997

Clinical Experience of Trabeculotomy for the Surgical Treatment of Aniridic Glaucoma

Misato Adachi; Christopher J. Dickens; John Hetherington; H. Dunbar Hoskins; Andrew G. Iwach; Patricia C. Wong; Ngoc Nguyen; Albert S. Ma

OBJECTIVE The purpose of this study is to determine the efficacy of initial trabeculotomy in the patient with aniridic glaucoma. DESIGN Clinical charts were reviewed. PARTICIPANTS Twenty-nine eyes of 16 patients with aniridia were studied. INTERVENTION Glaucoma surgery was performed. As an initial procedure, trabeculotomy was performed in 12 eyes, other surgery was performed in 17 eyes (trabeculectomy, 5; goniotomy, 5; other, 7). MAIN OUTCOME MEASURES Success was defined as an intraocular pressure (IOP) of 21 mmHg or lower, and no further surgery was performed. RESULTS Ten (83%) of 12 eyes obtained IOP control after first (6 eyes) or second (4 eyes) trabeculotomy with a mean follow-up period of 9.5 years. Five eyes maintained visual acuity of 20/40 to 20/200. No serious complications were found after trabeculotomy. Three (18%) of 17 eyes were controlled with the first glaucoma surgery other than trabeculotomy (goniotomy, trabeculectomy, trabeculectomy combined with trabeculotomy, and Molteno implant). Good IOP control was obtained in 8 (47%) of 17 eyes after several surgeries with a mean follow-up period of 10.4 years. Four of 17 eyes became phthisical. CONCLUSION This study suggests that trabeculotomy is the preferred initial operation for uncontrolled glaucoma with aniridia.


Ophthalmology | 2003

Long-term results of noncontact neodymium:yttrium–aluminum–garnet cyclophotocoagulation in neovascular glaucoma

Maria F Delgado; Christopher J. Dickens; Andrew G. Iwach; Gary D. Novack; Diana S Nychka; Patricia C. Wong; Ngoc Nguyen

PURPOSE To determine the long-term efficacy and safety of noncontact transscleral neodymium:yttrium-aluminum-garnet (Nd:YAG) cyclophotocoagulation (CP) for the treatment of neovascular glaucoma (NVG). DESIGN Retrospective, noncomparative, interventional case series. PARTICIPANTS One hundred fifteen eyes of 111 subjects treated from December 1987 to January 2001. METHODS Eyes with uncontrolled NVG underwent noncontact Nd:YAG CP. Treatment parameters and pretreatment and posttreatment intraocular pressures (IOP) were reviewed. Preoperative and postoperative IOP were compared using a paired Students t test. Success was defined as an IOP </=22 mmHg, with or without medications, in the absence of phthisis bulbi, and without having undergone further surgical procedures. Results were subjected to a Kaplan-Meier life-table analysis. RESULTS Mean follow-up was 27.0 +/- 34.3 months (range, 1-148 months). Mean preoperative IOP was 47.4 +/- 11.1 mmHg (range, 26-70 mmHg). Mean postoperative IOP was 18.3 +/- 12.2 mmHg (range, 0-44 mmHg). The mean number of treatment sessions was 1.4 +/- 0.7 (range, 1-6), with 82 eyes (71.3%) having only one treatment. Kaplan-Meier survival analysis showed a probability of continued success at 1 year of 65.0%, at 3 years of 49.8%, and at 6 years of 34.8%. Phthisis developed in 8.6% of the eyes. CONCLUSIONS Noncontact Nd:YAG CP provides long-term IOP reduction in eyes with medically uncontrolled NVG. This can be associated with complications that include inflammation, visual loss, and hypotony. Repeat treatment may be necessary.


Ophthalmology | 1994

Errors in the Diagnosis of Visual Field Progression in Normal-tension Glaucoma

Michael Schulzer; P. Juhani Airaksinen; Wallace L.M. Alward; Marcel Amyot; Douglas R. Anderson; Gordon Balazsi; Pierre Blondeau; L. Frank Cashwell; John S. Cohen; Daniel Desjardins; Christopher J. Dickens; Gordon R. Douglas; Stephen M. Drance; Frederick Feldman; H. Caroline Geijssen; Alana Grajewski; Erik L. Greve; John Hetherington; Dale Heuer; Elizabeth Hodapp; H. Dunbar Hoskins; Andrew G. Iwach; Henry Jampel; Oscar Kasner; Yoshiaki Kitazawa; Rauni Komulainen; Ralph Levene; Jeffrey M. Liebmann; Frederick S. Mikelberg; R. Mills


Ophthalmology | 1993

Subconjunctival THC:YAG (“Holmium”) Laser Thermal Sclerostomy Ab Externo: A One-year Report

Andrew G. Iwach; H. Dunbar Hoskins; Michael V. Drake; Christopher J. Dickens


Ophthalmology | 1993

Subconjunctival THC:YAG (“Holmium”) Laser Thermal Sclerostomy Ab Externo

Andrew G. Iwach; H. Dunbar Hoskins; Michael V. Drake; Christopher J. Dickens

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Andrew G. Iwach

University of British Columbia

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Andrew G. Iwach

University of British Columbia

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H. Dunbar Hoskins

University of British Columbia

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John Hetherington

University of British Columbia

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Justin S. Mora

University of California

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H. Dunbar Hoskins

University of British Columbia

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