Biomedical subjects

A Tim Johnson

Publications and source records attributed to A Tim Johnson.

4 recordsLinked to original sources

PubMed2005

Interim results of the United States investigational device study of the Ophtec capsular tension ring.

PURPOSE: To evaluate the safety and efficacy of the Ophtec capsular tension ring (CTR) in providing capsular support during and/or after cataract extraction in cases of a weak or partially broken ciliary zonule. DESIGN: Phase III multicenter, nonrandomized, investigational device study. PARTICIPANTS: Twelve investigators at 9 sites enrolled 224 subjects and placed 255 CTRs. METHODS: Capsular tension rings were placed in patients who were found to have a weakened or partially broken ciliary zonule comprising <34% of the circumference of the lens capsule. Two CTR models were evaluated, with noncompressed diameters of 12 mm and 13 mm. Patients were examined preoperatively, intraoperatively, and postoperatively at day 1 and months 1, 3, 6, and 12. MAIN OUTCOME MEASURES: Rate of successful stabilization of the capsular bag and intraocular lens (IOL) centration, complications, and adverse events. RESULTS: Interim results from this ongoing study indicate that immediately after surgery 98.8% of IOLs were centered and 1.2% of the IOLs implanted (3/251) were not centered. Subsequently, the prevalence of decentered IOLs was 1.7% (4/236) 3 months after surgery, 3.8% (8/211) 6 months after surgery, and 2.3% (4/172) 12 months after surgery. The primary complication was posterior capsular opacification, which is unlikely to be a complication of CTR insertion. Neodymium:yttrium-aluminum-garnet laser capsulotomies have been performed in 12.8% of eyes by 12 months (22/172). CONCLUSIONS: Ophtec CTR models 275 and 276 safely provided capsular support during and after cataract surgery in cases where the zonule was weak or partially broken.

Adult↗

PubMed2003

Evaluation of optineurin sequence variations in 1,048 patients with open-angle glaucoma.

PURPOSE: To investigate the association of sequence variations in the optineurin (OPTN) gene in patients with open-angle glaucoma. DESIGN: Prospective case control study. METHODS: The OPTN gene was screened for sequence variations using a combination of single-strand conformational polymorphism analysis and automated DNA sequencing. A total of 1,299 subjects (1048 glaucoma patients and 251 controls) were screened for variations in the four portions of the gene that had been previously associated with glaucoma. A subset of these subjects (376 patients and 176 controls) was screened for variations in the entire coding sequence. Twenty-four percent of the patients and 35% of the controls were Japanese, whereas the remainder were predominantly Caucasian. Allele frequencies were compared with the Fisher exact test. RESULTS: The OPTN sequence variations were not significantly associated with any form of high-tension open-angle glaucoma. One proband with familial normal-tension glaucoma was found to harbor the previously reported Glu50Lys variation. Another previously reported change, Met98Lys, was associated with normal-tension glaucoma in Japanese but not in Caucasian patients. CONCLUSIONS: This study provides some additional evidence for the association of the Glu50Lys OPTN sequence variation with familial normal tension glaucoma. However, because familial normal-tension glaucoma is so rare, this change seems to be responsible for less than 0.1% of all open-angle glaucoma. The Arg545Gln variation is likely to be a nondisease-causing polymorphism. The Met98Lys change may be associated with a fraction of normal-tension glaucoma in patients of Japanese ethnicity.

Base Sequence↗

PubMed2002

Variations in the myocilin gene in patients with open-angle glaucoma.

OBJECTIVE: To determine the prevalence and associated phenotype of myocilin (MYOC) coding sequence variations and a specific promoter polymorphism (MYOC.mt1) in patients with glaucoma and glaucoma suspects. METHODS: A consecutive, unselected series of 779 patients (652 with open-angle glaucoma and 127 glaucoma suspects) were recruited from a university medical center and clinically characterized. The coding sequences of the MYOC gene and the MYOC.mt1 locus in the promoter region were screened for sequence variations. We determined the prevalence of MYOC coding sequence mutations and the MYOC.mt1 promoter polymorphism. We also compared the clinical features of individuals with and without mutations and the MYOC.mt1 promoter polymorphism. RESULTS: Plausible disease-causing sequence variations (DCVs) in the MYOC gene were found in 3.0% of the entire group. Such variations were found in patients with most forms of open-angle glaucoma studied. Patients with primary open-angle glaucoma (POAG) who harbored coding sequence DCVs were clinically similar to patients without them. Patients who harbored the rarer allele of the MYOC.mt1 promoter polymorphism were no different in any measure of disease severity from those who harbored the more common allele. CONCLUSIONS: MYOC DCVs were found in approximately 3% of patients with glaucoma and glaucoma suspects. The 2 alleles of the MYOC.mt1 promoter polymorphism were equally distributed among patients with POAG and healthy control subjects. Patients with POAG who harbored the rarer allele of the MYOC.mt1 promoter polymorphism were no different from those with the more common variant in any measure of disease severity. CLINICAL RELEVANCE: Testing for the MYOC.mt1 promoter polymorphism appears to be of no value in the evaluation of patients with glaucoma.

Adult↗

PubMedDate not supplied

Teaching and assessing surgical competency in ophthalmology training programs.

BACKGROUND AND OBJECTIVE: The Accreditation Council for Graduate Medical Education (ACGME) has mandated implementation of six new competencies in resident training in the United States. An implementation strategy is proposed to teach and assess cataract surgical competence. PATIENTS AND METHODS: An intradepartmental Task Force for the ACGME competencies reviewed the literature for assessment tools to develop an implementation matrix for assessing surgical competence. RESULTS: "Good practices" (gleaned from the literature) were adapted for the institution's needs and tested, including (1) written and explicit goals or objectives for each stage of training; (2) substitution of a criterion-referenced (Dreyfus model) scoring rubric for a norm-referenced, peer-benchmarked global evaluation; (3) use of formative rather than summative feedback; (4) incorporation of deliberate practice (Ericsson model); and (5) portfolio-based documentation of sentinel event markers and remediation. CONCLUSION: An implementation matrix for teaching and assessing surgical competence might be useful for local compliance with the ACGME mandate.

Cataract Extraction↗