Biomedical subjects

Robert Chong

Publications and source records attributed to Robert Chong.

3 recordsLinked to original sources

PubMed2006

Magnification-corrected photodynamic therapy.

BACKGROUND: To present a method for performing photodynamic therapy (PDT) with a constant predictable light fluence based on actual laser spot magnification. METHODS: A calibrated Gullstrand-type model eye with a scale of half circles in the centre of the artificial fundus was used for this study. The axial length of the model eye was set to different values ranging from 20 to 31 mm, and the actual laser spot magnification of four indirect condensing laser lenses were determined using a PDT laser unit. RESULTS: Equations for determining the actual laser spot magnification were calculated for each laser lens. The total change in laser spot magnification from hyperopia (axial length 20 mm) to myopia (axial length 31 mm) was -20% to +24.8% for Mainster Standard lens (Ocular Instruments Inc, Bellevue, Washington, USA), -15.7% to +27.7% for Mainster Wide Field lens (Ocular Instruments Inc), -16.3% to +33.1% for Volk Transequator lens (Volk Optical Inc, Mentor, Ohio, USA), and -19.2% to +24.4% for Volk PDT Laser lens (Volk Optical Inc). CONCLUSIONS: Axial length of the eye has a considerable effect on PDT laser spot magnification when an indirect laser lens is used. By calculating the actual laser spot magnification in conjunction with knowledge of the true greatest linear dimension of the neovascular lesion, the clinician may be able to deliver a constant predictable amount of light fluence to the fundus independent of the axial length of the PDT treating eye.

Choroidal Neovascularization↗

PubMed2005

Spectrum of clear corneal incision cataract wound infection.

PURPOSE: To describe the presentation, management, and outcome of 5 patients who presented with main-port or side-port wound infection after uneventful clear corneal cataract surgery. SETTING: Ophthalmic Surgery Centre, Chatswood, and Department of Ophthalmology, Prince of Wales Hospital, Randwick, Australia, and Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom. METHODS: This retrospective case series comprised 5 patients who had uneventful clear corneal phacoemulsification surgery and developed either a main-port or side-port wound infection. The clinical features, microbiologic studies, management, and results are reported. RESULTS: The median age of the patients was 79 years. Infection of the main-port incision occurred in 3 cases and of the side port in 2 cases. The patients presented from a few days to several weeks after uneventful phacoemulsification. In 2 cases, the bacteria Pseudomonas aeruginosa and Staphylococcus aureus were isolated. In 1 case, the fungus Aspergillus was isolated and required extensive medical and surgical treatment. In the other 2 cases; empiric antimicrobial therapy was given because no organism was isolated in 1 case, and in the other milder case, microbiological investigations were not performed. Final visual acuity was 6/4 in 2 cases and 6/5, 6/12, and 6/18 in 1 case each. CONCLUSIONS: Bacterial or fungal wound infection can present within days or even several weeks following clear corneal cataract surgery. Patients with ocular discomfort or blurred vision after such surgery should be advised to report promptly. Rapid identification and appropriate management of patients with clear corneal wound infection can result in good visual outcomes.

Aged↗

PubMed2002

Survey of major chronic iIlnesses and hospital admissions via the emergency department in a randomized older population in Randwick, Australia.

OBJECTIVE: To find out if patients with chronic illnesses living in the community are at risk of unplanned hospital admissions through emergency departments; what types of chronic illnesses may be putative risk factors; and if an increase in the number of chronic illnesses may be associated with increased risk. METHODS: The survey included the completion of a standardized questionnaire for medical illnesses in a random sample of older people dwelling in the community and analysis of admission records to our hospital. The principal diagnoses for admissions were recorded. The risk factors for admissions were analysed. RESULTS: Five hundred and twenty-six (239 men and 287 women) people aged 55 years and over were interviewed. Musculoskeletal disorders, hypertension, gastrointestinal disorders and ischaemic heart disease were the most frequently reported of the chronic illnesses surveyed. A total number of 70 people from the survey group with a total of 115 admissions through emergency departments were recorded. Using logistic regression model, hypertension, ischaemic heart disease and age were found to be risk factors for emergency admissions amongst this group of community-dwelling residents. The ratios were 2.03 (95% confidence interval (CI): 1.2-3.44), 2.02 (95% CI: 1.16-3.49) and 1.05 (95% CI: 1.02-1.09), respectively. Furthermore, multiple (three or more) chronic illnesses were found to be a strong predictor of hospital admission via emergency department (chi-square = 16.647, DF = 1, P-value < 0.001). CONCLUSION: We conclude that there was significant association between multiple chronic diseases and emergency admissions for older people. Of these, hypertension and ischaemic heart disease were found to be significant predictors. Age per se was found to be of borderline significance.

Aged↗