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Biomedical subjects

Margaret A Chang

Publications and source records attributed to Margaret A Chang.

7 recordsLinked to original sources
PubMed2005

The association between myopia and various subtypes of lens opacity: SEE (Salisbury Eye Evaluation) project.

PURPOSE: To establish the relationship between myopia and lens opacity. DESIGN: Population-based cross-sectional study. PARTICIPANTS: Two thousand five hundred twenty participants from the Salisbury Eye Evaluation aged 65 to 84 years. METHODS: Participants filled out questionnaires regarding medical history, social habits, and a detailed history of distance spectacle wear. They underwent a full ocular examination. Lens photographs were taken for assessment of lens opacity using the Wilmer grading system. Multivariate logistic regression models using generalized estimating equations were used to analyze the relationship between lens opacity type and degree of myopia, while accounting for potential confounders. MAIN OUTCOME MEASURES: Presence of posterior subcapsular opacity, cortical opacity, or nuclear opacity. RESULTS: Significant associations were found between myopia and both nuclear and posterior subcapsular opacities. For nuclear opacity, the odds ratios (ORs) were 2.25 for myopia between -0.50 diopters (D) and -1.99 D (P<0.001), 3.65 for myopia between -2.00 D and -3.99 D (P<0.001), 4.54 for myopia between -4.00 D and -5.99 D (P<0.001), and 3.61 for myopia -6.00 D or more (P = 0.002). For posterior subcapsular cataracts, ORs were 1.59 for myopia between -0.50 D and -1.99 D (P = 0.11), 3.22 for myopia between -2.00 D and -3.99 D (P = 0.002), 5.36 for myopia between -4.00 D and -5.99 D (P<0.001), and 12.34 for myopia -6.00 D or more (P<0.001). No association was found between myopia and cortical opacity. The association between posterior subcapsular opacity and myopia was equally strong for those wearing glasses by age 21 years and for those without glasses; for nuclear opacity, significantly higher ORs were found for myopes who started wearing glasses after age 21. CONCLUSIONS: These results confirm the previously reported association between myopia, posterior subcapsular opacity, and nuclear opacity. Furthermore, the strong association between early spectacle wear and posterior subcapsular opacity among myopes, absent for nuclear opacity, suggests that myopia may precede opacity in the case of posterior subcapsular opacity, but not nuclear opacity. Measures of association between posterior subcapsular opacity and myopia were stronger in the current study than have previously been found. Longitudinal studies to confirm the association are warranted.

Aged↗
PubMed2005

Bilateral endogenous endophthalmitis in a patient with hemoglobin SC disease.

CASE REPORT: Bilateral endogenous endophthalmitis in the setting of pneumococcal bacteremia was diagnosed in a woman with hemoglobin SC disease who presented with decreased vision, increased redness, burning pain, and photophobia. All gram stains and cultures remained negative, and the exact source of her bacteremia was not clear. Nonetheless, early diagnosis and prompt treatment were vital to avoiding a visually devastating outcome. COMMENTS: Aggressive treatment with intravitreal and systemic antibiotics, with or without pars plana vitrectomy, was successful in restoring final visual acuity.

Anti-Bacterial Agents↗
PubMed2004

Total anterior corneal surface and epithelial stem cell harvesting: current microkeratomes and beyond.

Currently, most corneal lamellar allografts are performed by manually dissecting donor corneoscleral material for transplantation. Manual dissection is technically challenging and time intensive, and excessive handling of tissue may decrease the likelihood of obtaining viable grafts. These mechanical factors, along with problems controlling immune rejection, have prevented limbal stem cell lamellar allografts in particular from becoming more widely used. Anterior lamellar keratoplasty is gaining in clinical importance and usage but is still only practiced by a limited number of surgeons. Recently, new mechanical and femtosecond laser microkeratomes have been adapted to harvest the anterior corneal surface, including the limbal stem cell region. Preliminary results have been encouraging and give hope that this technique may prove to be of benefit to patients in the future.

Corneal Opacity↗
PubMed2003

Corneal edema resolution after "descemetorhexis".

A 79-year-old woman had left eye phacoemulsification complicated by inadvertent excision of Descemet's membrane (DM). One day postoperatively, the visual acuity was counting fingers with diffuse corneal edema. The patient was treated medically, with gradual resolution of the corneal edema over a 6-month period. The torn edge of DM could be visualized as the edema cleared, and no endothelial cell count could be obtained centrally. Approximately 1 year postoperatively, the central endothelial cell count was 2114 cells/mm(2) in the right eye and 827 cells/mm(2) in the left eye. The decreased cell count, increased polymegethism, and pleomorphism suggested that endothelial cells migrated to cover the stromal surface area in the absence of DM.

Aged↗
PubMed2002

Outcome of phacoemulsification after pars plana vitrectomy.

PURPOSE: To compare the outcome of phacoemulsification surgery in patients with and without prior vitrectomy, adjusted for confounding factors. DESIGN: Retrospective cohort study. PARTICIPANTS AND CONTROLS: Thirty-one consecutive eyes undergoing phacoemulsification after pars plana vitrectomy (PPV) and 116 consecutive eyes undergoing phacoemulsification without previous PPV. METHODS: Office records of the operating surgeons were reviewed for age, gender, type of cataract, vitrectomy status, best-corrected visual acuity (BCVA) before and after phacoemulsification, intraoperative difficulties, and postoperative complications. Bivariate analyses between these predictors and the main outcome, BCVA of 20/40 or better after phacoemulsification, were performed using Pearson's chi-square tests. An adjusted analysis of the relationship between outcome and vitrectomy status was performed with logistic regression. Pearson's chi-square tests were used to compare type of cataract, intraoperative difficulties, and postoperative complications in study and control eyes. MAIN OUTCOME MEASURES: BCVA of 20/40 or better after phacoemulsification, rates of intraoperative difficulties, and postoperative complications. RESULTS: The most common indication for PPV was macular hole. The average interval from PPV to phacoemulsification was 15.4 months. Study eyes were followed for an average of 10 months compared with 6.6 months for controls. Study eyes were more likely than controls to have predominantly nuclear sclerotic cataracts (P = 0.002). After cataract extraction, 24 of 31 study eyes (77.4%) and 110 of 116 control eyes (94.8%), had BCVAs of 20/40 or better. After adjusting for confounders, eyes without previous vitrectomy were 3.44 times more likely to obtain a BCVA of 20/40 or better than eyes with prior PPV, but this difference was not statistically significant (95% CI, 0.72-16.67). Only 3 of 31 (9.7%) study and 11 of 116 (9.4%) control eyes had intraoperative difficulties (P = 0.47). Posterior capsule plaque was the most common intraoperative difficulty in study eyes; small pupil requiring stretching or iris hooks was most common in controls. Only 1 of 31 (3.2%) study eyes had a postoperative complication other than posterior capsule opacification compared with 18 of 116 (15.5%) controls (P = 0.07). CONCLUSIONS: A large proportion of patients with prior PPV obtain good visual acuity after phacoemulsification. We did not find significantly higher rates of intraoperative difficulties or postoperative complications compared with controls. The benefits of phacoemulsification seem to be limited only by retinal comorbidity.

Adolescent↗
PubMedDate not supplied

Infections following laser in situ keratomileusis: an integration of the published literature.

Infections occurring after laser in situ keratomileusis (LASIK) surgery are uncommon, but the number of reports have steadily increased in recent years. This systematic, comprehensive review and analysis of the published literature has been performed in order to develop an integrative perspective on these infections. We have stratified the data by potential associations, microbiology, treatment, and the degree of visual loss, using Fisher's exact tests and Student's t-tests for analysis. In this review, we found that Gram-positive bacteria and mycobacterium were the most common causative organisms. Type of postoperative antibiotic and steroid use was not associated with particular infecting organisms or severity of visual loss. Gram-positive infections were more likely to present less than 7 days after LASIK, and they were associated with pain, discharge, epithelial defects, and anterior chamber reactions. Fungal infections were associated with redness and tearing on presentation. Mycobacterial infections were more likely to present 10 or more days after LASIK surgery. Moderate or severe visual reductions in visual acuity occurred in 49.4% of eyes. Severe reductions in visual acuity were significantly more associated with fungal infections. Flap lift and repositioning preformed within 3 days of symptom onset may be associated with better visual outcome.

Adolescent↗