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Biomedical subjects

Robert F Lam

Publications and source records attributed to Robert F Lam.

11 recordsLinked to original sources
PubMed2006

Comparison of outcomes of primary scleral-fixated versus primary anterior chamber intraocular lens implantation in complicated cataract surgeries.

OBJECTIVE: To compare the visual outcomes and complication profiles of primary scleral-fixated intraocular lens (SFIOL) versus primary anterior chamber intraocular lens (ACIOL) implantation in cataract surgeries complicated by inadequate capsular support. DESIGN: Retrospective, interventional, comparative cases series. PARTICIPANTS: Thirty-six eyes of 36 patients undergoing SFIOL implantation (group 1) and 46 eyes of 46 patients undergoing ACIOL implantation (group 2). METHODS: Retrospective analysis of medical records of a consecutive series of complicated cataract surgeries with primary SFIOL or ACIOL implantation. MAIN OUTCOME MEASURES: Postoperative best-corrected visual acuity (BCVA), intraoperative and postoperative complications, if any, and postoperative corneal endothelial cell counts. A multiple linear regression model was constructed with postoperative BCVA as the dependent variable and with IOL group (SFIOL vs. ACIOL), preoperative BCVA, surgeon's operative experience, planned operation, and patient's age as independent variables. RESULTS: Fifty-eight percent (group 1) and 37% (group 2) of patients underwent phacoemulsification, whereas the rest underwent extracapsular cataract extraction. The mean postoperative follow-up was 33.4+/-17.9 months (range, 6-61 months). Postoperative Snellen BCVA of 20/40 or better was achieved in 47.2% (group 1) and 71.7% (group 2) of patients (P = 0.038). Regression analysis showed that primary ACIOL implantation was associated with a significantly better postoperative BCVA of -0.157 on the logarithm of minimum angle of resolution scale (95% confidence interval, -0.306 to -0.007; P = 0.040), compared with primary SFIOL implantation. Although both the number of eyes with complications and the total number of complications were higher in the SFIOL group, the differences in early (P = 0.073) and late (P = 0.377) complications were not statistically significant. CONCLUSIONS: The results indicate that satisfactory results are achieved with primary implantation of current open-loop ACIOLs during cataract surgery complicated by loss of posterior capsule integrity. Eyes with these IOLs fared better than a cohort of eyes undergoing SFIOL implantation in a similar situation, at intermediate-term follow-up. Further prospective clinical trials with longer follow-up may help to evaluate the long-term visual outcomes and complication profiles after primary implantation of these lenses.

Aged↗
PubMed2006

Pars plana vitrectomy and perfluoropropane (C3F8) tamponade for retinal detachment due to myopic macular hole: a prognostic factor analysis.

PURPOSE: To determine the prognostic factors associated with anatomical success in the treatment of retinal detachment (RD) due to myopic macular hole by pars plana vitrectomy (PPV) and perfluoropropane (C3F8) gas tamponade. DESIGN: Retrospective, interventional, comparative case series. METHODS: In an institutional setting, 57 eyes with myopic macular hole RDs treated by PPV and C3F8 tamponade, with or without concomitant internal limiting membrane (ILM) peeling, endolaser photocoagulation, and/or phacoemulsification, were analyzed. Outcome measures were anatomical success, defined as closure of macular hole with reattachment of the surrounding retina, and postoperative best-corrected visual acuity (BCVA). RESULTS: The mean postoperative follow-up was 26.9 +/- 16.5 months. The anatomical success rate after primary PPV and C3F8 tamponade was 63.2%. Regression analysis showed that shorter axial lengths (odds ratio [OR] = 6.73, 95% confidence interval [95% CI] 1.86 to 12.22, P = .010), concomitant ILM peeling (OR 1.59, 95% CI 1.14 to 2.38, P = .013), and shorter duration of macular hole RD (OR 0.81, 95% CI 0.67 to 0.98, P = .033) were associated with a higher anatomical success. The mean pre- and postoperative BCVAs were 1.430 +/- 0.273 (range, 0.523 to 1.700) and 1.403 +/- 0.271 (range, 0.699 to 1.800) logarithm of minimal angle of resolution units, respectively. The postoperative BCVA was significantly better in eyes with macular hole closure than in eyes without (P = .021). CONCLUSIONS: Axial length, concomitant ILM peeling, and duration were important prognostic factors for PPV and C3F8 tamponade in the treatment of myopic macular hole RDs.

Adult↗
PubMed2006

How evidence-based are publications in clinical ophthalmic journals?

PURPOSE: To evaluate the methodological quality and level of evidence of publications in four leading general clinical ophthalmology journals. METHODS: All 1919 articles published in the American Journal of Ophthalmology, Archives of Ophthalmology, British Journal of Ophthalmology, and Ophthalmology in 2004 were reviewed. The methodological rigor and the level of evidence in the articles were rated according to the McMaster Hedges Project criteria and the Oxford Centre for Evidence-Based Medicine levels of evidence. RESULTS: Overall, 196 (24.4%) of the 804 publications that were included for assessment met the Hedges criteria. Articles on economics evaluation and those on prognosis achieved the highest passing rate, with 80.0% and 74.4% of articles, respectively, meeting the Hedges criteria. Publications on etiology, diagnosis, and treatment fared less well, with respective passing rates of 28.3%, 20.2%, and 14.7%. Published systematic reviews and randomized controlled trials were uncommon in the ophthalmic literature, at least in these four journals during 2004. According to the Oxford criteria, 57.6% of the articles were classified as level 4 evidence compared with 18.1% classified as level 1. Articles on prognosis had the highest proportion (43.0%) rated as level 1 evidence. Generally, articles that reached the Hedges threshold were rated higher on the level-of-evidence scale (Spermans rho = 0.73; P < 0.001). CONCLUSIONS: The methodological quality of publications in the clinical ophthalmic literature was comparable to that in the literature of other specialties. There was substantial heterogeneity in quality between different types of articles. Future methodological improvements should focus on the areas identified as having the largest deficiencies.

Biomedical Research↗
PubMed2005

Retained presumed intraocular cotton fiber after cataract operation: long-term follow-up with in vivo confocal microscopy.

PURPOSE: To evaluate the long-term clinical outcomes in eyes with retained presumed intraocular cotton fibers after cataract surgery. SETTING: Hong Kong Eye Hospital, Hong Kong, The People's Republic of China. METHODS: A retrospective review of 19 eyes with retained presumed intraocular cotton fibers after cataract surgery was performed. Outcome measures were fiber-related complications. In vivo confocal microscopy was performed in eyes with entrapped cotton fibers at the wound site. RESULTS: The duration of retained presumed cotton fibers ranged from 5 to 110 months (mean 42.3 months). No complications were noted in any of these eyes, including endophthalmitis, persistent uveitis, or corneal endothelial cell loss. In vivo confocal microscopy in eyes with entrapped fibers at the wound site showed normal corneal endothelium morphology with no keratocyte activation or inflammatory response. CONCLUSIONS: Retained presumed fibers after cataract operations are more common than anticipated. In contrast to other organic foreign bodies, these retained fibers appear to be well tolerated. Conservative treatment can be adopted for these fibers as these pose minimal toxicity to the eye.

Adolescent↗
PubMed2005

Macular pigment optical density in a Chinese sample.

PURPOSE: Extensive efforts have been devoted to determining the macular pigment optical density (MPOD) in Caucasian subjects. Unfortunately, no such data in ethnic groups with naturally dark irises are currently available. In this study, we report the values in a sample of Chinese subjects. METHODS: The MPOD was measured psychophysically using a densitometer at 0.25 degrees , 0.50 degrees , 1.00 degrees , and 2.00 degrees eccentricity from the foveal center in 92 Chinese subjects. RESULTS: The spatial profile for the averaged MPOD was approximately exponential in form and showed a decline with age (r = -0.23). Subjects aged below 60 years had significantly higher averaged MPOD than those aged 60 years or above. Significant gender differences, in favor of males, were also found in the middle-age groups. CONCLUSIONS: Our study reports for the first time the MPOD in a Chinese population. Baseline information on MPOD would aid future research in preventive measures against age-related macular degeneration.

Adolescent↗
PubMed2005

Extent and predictors of microbial hand contamination in a tertiary care ophthalmic outpatient practice.

PURPOSE: To measure the extent of microbial hand contamination among ophthalmologists during routine clinic practice and examine its association with hand cleansing practices and beliefs, glove use, and patient load. METHODS: This was a single-masked analysis of resident and transient flora of ophthalmologists before and after patient examination and after handwashing by agar imprints of the dominant hand. Standardized questionnaires were used to collect information concerning subjects' hand cleansing practices and patient load. RESULTS: Of the 108 cultures, 107 (99.1%) were culture positive, yielding 15 separate organisms. Gram-negative bacilli were the most common transient flora, followed by Gram-positive cocci and fungi. Thirty-five (97.2%) ophthalmologists were culture positive for at least one resident and 8 (22.2%) ophthalmologists were culture positive for at least one transient organism, before patient contact. Regression models showed alcohol-based hand rub use, transient and resident floral load before patient contact, and patient load collectively accounted for 58.7% of the variance in resident floral load after patient contact. Use of alcohol-based hand rubs was associated with a mean resident floral reduction of 324.4 CFUs (95% confidence interval [CI] = 185.4 to 463.5; P < 0.01) and 31.6 CFUs (95% CI = 1.2 to 62.0; P < 0.05) after patient contact and handwashing, respectively. Handwashing with chlorhexidine was a significant predictor for transient floral load after handwashing (unstandardized beta = -17.2; 95% CI = -10.2 to -24.2; P < 0.01). CONCLUSIONS: The extent of contamination with pathogenic organisms after contact with eye outpatients, who have traditionally been perceived as relatively "clean," was of concern. Previously identified risk factors for hand contamination in inpatient settings, such as patient load, only explained a small proportion of variance in microbial load in the ophthalmic outpatient setting.

Bacteria↗
PubMed2004

Prevalence, incidence, and progression of myopia of school children in Hong Kong.

PURPOSE: To determine the prevalence, incidence, and progression of myopia of Chinese children in Hong Kong. METHODS: A cross-sectional survey was initially conducted. A longitudinal follow-up study was then conducted 12 months later. RESULTS: A total of 7560 children of mean age 9.33 (95% confidence interval [CI] = 9.11-9.45; range, 5-16) participated in the study. Mean spherical equivalent refraction (SER) was -0.33 D (SD = 11.56; range, -13.13 to +14.25 D). Myopia (SER <or= -0.50 D) was the most common refractive error and was found in 36.71% +/- 2.87% (SD) of children. Prevalence of myopia correlated positively with older age. Children aged 11 years were almost 15 times more likely to have myopia than were children younger than 7 years (Odds ratio [OR] = 14.81; 95% CI = 14.17-15.48). Incidence of myopia was 144.1 +/- 2.31 (SD) per 1000 primary school children per annum. Increasing age was correlated with increased incidence of myopia, with highest risk in children ages 11 years (OR = 2.27; 95% CI = 2.11-2.44). The average annual change in SER for children with myopia (SER <or= -0.50 D) was -0.63 D (SD = 3.44) compared with -0.29 D (SD = 2.96) for those who were not myopic at the beginning of the study (P < 0.001). CONCLUSIONS: The results show that the prevalence and progression of myopia in Hong Kong children was much higher than those previously reported in Western countries. The long-term socioeconomic impact of these findings warrants further studies.

Adolescent↗