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Biomedical subjects

A A Chang

Publications and source records attributed to A A Chang.

16 recordsLinked to original sources
PubMed2005

Vitrectomy with short term postoperative tamponade using perfluorocarbon liquid for giant retinal tears.

AIM: To determine the efficacy and safety of perfluorocarbon liquid as a short term postoperative tamponade in patients with retinal detachment from giant retinal tears. METHOD: A retrospective consecutive case series of patients with retinal detachment from giant retinal tears who underwent vitrectomy using perfluorocarbon liquid as a short term postoperative internal tamponade. The perfluorocarbon liquid was removed 5-14 days (mean 7.5 days) later and replaced by gas or silicone oil. Scleral buckling was performed in some cases with proliferative vitreoretinopathy. The crystalline lens was removed if there was interference with the surgical view or if it was subluxated. The success rate of retinal reattachment, visual outcome, and postoperative complications were assessed. RESULTS: A total of 62 eyes of 61 patients with a follow up of 8-69 months (mean 24.5 months) were included. All retinas were attached intraoperatively. 14 eyes (22.6%) developed re-detachment and additional operations were performed in 13 eyes. At final visit, 58 eyes (93.5%) had retinas that remained attached with visual acuity 6/12 or better in 27 eyes (46.5%). The visual acuity improved in 34 eyes (54.8%) with 28 eyes (45.2%) improving at least two Snellen lines, it was unchanged in 20 eyes (32.3%), and was worse in eight eyes (12.9%). Three patients developed glaucoma that was controlled medically. There was no retained perfluorocarbon liquid in any eyes. CONCLUSION: Perfluorocarbon liquid appears safe and effective to use as a short term postoperative tamponade in management of retinal detachment from giant retinal tears.

Adolescent↗
PubMed2000

Indocyanine green angiographic features of varix of the vortex vein ampulla.

Varix of the vortex vein ampulla is a rare, benign, asymptomatic condition, which may be confused with a choroidal naevus or melanoma. A 28-year-old man was referred to a tertiary retinal practice with a diagnosis of choroidal naevus. The lesion was an elevated choroidal mass in the superonasal peripheral retina measuring 2 by 1 disc diameters. It was dark red to burgundy in colour and disappeared under digital pressure applied to the globe. The methods used in diagnosis were colour fundus photography, fluorescein angiography and indocyanine green angiography using a scanning laser ophthalmoscope. On fluorescein angiography the lesion was initially hypofluorescent, becoming isofluorescent 25 s after dye injection. Indocyanine green angiography demonstrated the lesion to be two separate dilatations of the vortex vein ampullae. The dilatations collapsed when pressure was applied to the globe. A choroidal mass that collapses under pressure applied to the globe should suggest a varix of the vortex vein ampulla. Indocyanine green angiography is useful in demonstrating the outline of the varix of the vortex vein ampulla.

Adult↗
PubMed2000

The macular hole: report of an Australian surgical series and meta-analysis of the literature.

PURPOSE: To report an Australian series of macular hole surgery by pars plana vitrectomy and fluid-gas exchange, and to identify factors influencing the outcome of the surgery through meta-analysis of the literature. METHODS: Fifty-six consecutive cases of macular hole were treated by pars plana vitrectomy, fluid-gas exchange and face-down positioning for at least 7 days, and prospectively followed for 3-12 months. Thirty-six reports of macular hole surgery were reviewed. A meta-analysis on the pre- and postoperative parameters was performed on 389 cases, in which case-specific data-points were available. RESULTS: In the current series, anatomical closure was achieved in all (100%) of 16 stage 2, and in 35 (87.5%) of 40 stage 3 or 4 macular holes. At least 2 logMAR lines of improvement in visual acuity were seen in 10 (62.5%) stage 2 and 20 (50.0%) stage 3 or 4 holes. Postoperative visual acuity was 6/12 or better in 10 (62.5%) stage 2 and 17 (42.5%) stage 3 or 4 holes. In both the current series and the meta-analysis, favourable surgical outcomes were associated with stage 2 macular holes, better preoperative visual acuity, and shorter preoperative duration. Adjuvant use was associated with a higher rate of anatomical closure but there was no clear benefit in terms of postoperative visual acuity. CONCLUSION: Our experience and the results of the meta-analysis suggest that macular hole surgery should be offered as early as possible once full-thickness neuroretinal defect occurs.

Aged↗
PubMed1999

Management of acute myocardial infarction in general medical wards in Sri Lanka.

The study was designed to evaluate the management of acute myocardial infarction in the general medical wards of the National Hospital of Sri Lanka. All patients with acute myocardial infarction admitted from September 1996 to August 1997, were evaluated with regard to the time delay in admission and drug treatment. The facilities for monitoring and resuscitation were also assessed. A total of 259 patients were included in the study, 173 males and 86 females. The median time delay from the onset of the pain to admission at the out-patients department was 12 hours and that between out-patients department admission and ward admission was 20 minutes. The median delay in obtaining a 12-lead electrocardiogram when the patient was in the ward was 90 minutes. Review of the data showed that thrombolytic therapy, beta-blockers and angiotensin-converting enzyme inhibitors are underused. Complications were common. All the medical wards had adequate monitoring and resuscitation facilities. With adequate training of doctors and the availability of specialised cardiac nurses, thrombolytic therapy can be used effectively in medical wards.

Acute Disease↗
PubMed1998

Histologic localization of indocyanine green dye in aging primate and human ocular tissues with clinical angiographic correlation.

OBJECTIVE: This study aimed to histologically localize indocyanine green (ICG) dye in the geriatric primate and human eye and to correlate these findings with clinical ICG angiography. DESIGN: The study design was a clinicopathologic correlation. PARTICIPANTS: Six eyes of three geriatric monkeys (Maccaca mulatta) with macular drusen, 19 to 29 years of age, housed at the California Primate Research Center and an enucleated human eye from a 66-year-old patient with choroidal melanoma were examined. INTERVENTION: All six monkey eyes and the human eye underwent clinical ICG angiography. Five monkey eyes were enucleated at varying intervals after intravenous ICG dye injection for histologic examination. One monkey eye was removed without prior ICG injection as an age-matched control. The human eye was enucleated after intravenous injection of ICG dye. MAIN OUTCOME MEASURES: Infrared fluorescence microscopy of freeze-dried tissue sections was performed to detect ICG fluorescence. Histologic sections were stimulated with an 810-nm diode laser, and the fluorescence emitted was detected with a Hamamatsu infrared camera. The images were digitally recorded. The distribution of fluorescence on histologic examination was correlated with the fluorescence of the clinical ICG angiogram. RESULTS: Infrared fluorescence microscopy of monkey sections localized fluorescence within retinal and choroidal vessels early after injection of ICG dye. The ICG fluorescence was seen in the extravascular choroidal stroma within 10 minutes after injection. The stromal fluorescence persisted in sections obtained 50 minutes after injection of ICG. The retinal pigment epithelium (RPE)-Bruch's membrane complex was brightly fluorescent in the middle- and late-stage histologic sections. Drusen deposits were brightly fluorescent at all timepoints examined. Similar findings were observed in freeze-dried tissue sections of the human eye. The fluorescence detected on histologic sections correlated closely with the fluorescence of the clinical ICG angiograms for the same interval. CONCLUSIONS: The ICG dye does not remain solely within the choroidal intravascular space but extravasates into the choroidal stroma and accumulates within the RPE. Extravascular ICG binds to drusen material. These findings will enhance the interpretation of clinical ICG angiography.

Aged↗
PubMed1997

An audit of structure, process and outcome of care of the diabetic clinic, National Hospital of Sri Lanka.

AIMS: To audit the structure, process and outcome of care. SETTING: The diabetic clinic, National of Hospital Sri Lanka (NHSL). METHODS: A previously validated MCQ paper of 10 questions which assessed knowledge of diabetes on insulin therapy, dietary management, management during acute illness and management of emergencies was administered to all patients. The function of the clinic was assessed using previously validated audit case record forms. MEASURES OF OUTCOME: Diabetes knowledge among patients, waiting times, bypassing of local institutions, availability of diagnostic equipment, screening activities and time spent for consultation. RESULTS: The clinic had a daily average attendance of 186 patients seen between 0800 to 1200 hours. A single medical officer spent 2.1 minutes for each patient. No screening was performed. There were no facilities to examine patients or for them to sit during consultation. The diabetes knowledge score was 15.1 (SD 3) from a maximum score of 40.43% had bypassed a local institution. Reasons for bypass included non-availability of drugs and the expectation of quality care at NHSL. Patients spent a mean of 1.5 (SD 0.7) hours travelling to the clinic and waited a mean of 1.56 (SD 0.4) hours to see the doctor and 1.3, (SD 0.12) hours to obtain drugs. CONCLUSIONS: The services of the diabetic clinic do not meet the standards expected of a clinic at a tertiary referral centre. Lack of planning and resources (space, manpower and management skills) can be identified as principal shortcomings.

Diabetes Mellitus↗
PubMed1996

Release of interleukin-12 in experimental Escherichia coli septic shock in baboons: relation to plasma levels of interleukin-10 and interferon-gamma.

Interleukin (IL)-12 is thought to be a key factor for the induction of interferon gamma (IFN-gamma), a cytokine essential for the lethal effects of endotoxin. We report here on the release of the nonfunctional subunit of IL-12, p40, as well as biologically active heterodimeric IL-12, p70, after administration of a lethal (n = 5) or sublethal (n = 8) dose of live Escherichia coli to baboons. Remarkably, on lethal challenge, peak levels of p40 were observed at 3 hours that were about twofold lower than those elicited after sublethal challenge (2,813 +/- 515 pg/mL v 4,972 +/- 732 pg/mL, P < .05). This disparity was also observed, although to a lesser extent, for IL-12 p70 antigen, of which maximum levels of 91 +/- 47 pg/mL and 151 +/- 41 pg/mL were measured 6 hours after a lethal or sublethal dose of E coli, respectively. Circulating p70 antigen correlated with IL-12 biologic activity (r = 0.869; P < .001). When comparing lethal to sublethal conditions, lower peak levels of IL-12 on lethal E coli sharply contrasted with higher levels of other proinflammatory cytokines, such as tumor necrosis factor (TNF)-alpha, IL-1beta, IL-6, and IL-8 observed in these animals. Lower IL-12 concentrations in the lethal group may have resulted in part from the enhanced production of IL-10, a known inhibitor of IL-12 synthesis in vitro, as peak levels of this cytokine 3 hours postchallenge inversely correlated with peak levels of IL-12, in particular p40 (r = -0.802; P < .01). Contrary to what might be expected if IFN-gamma were solely induced by IL-12, lethally challenged baboons generated threefold more IFN-gamma at 6 hours than those receiving a sublethal dose (P < .05). Moreover, higher levels of IFN-gamma were associated with lower p40/p70 ratios, suggesting that, in agreement with observations in vitro, IFN-gamma may have preferentially upregulated the release of p70 over p40. These data show that IL-12 is released in experimental septic shock in nonhuman primates and suggest that IL-10 and IFN-gamma are involved in the regulation of this release. Furthermore, this study indicates that the systemic release of IL-12 might be essential, but is not likely sufficient, to promote lethal production of IFN-gamma in sepsis.

Animals↗
PubMed1995

Clinical exophthalmometry: a comparative study of the Luedde and Hertel exophthalmometers.

Exophthalmometry, the quantitative assessment of the position of the globe in the orbit, is a clinically useful measurement. The purpose of this study was to examine the performance of a simple exophthalmometer that would lend itself to accurate and convenient use in clinical practice. In this study, two observers independently performed exophthalmometry on 100 eyes using the Hertel and Luedde instruments. The results were compared between instruments and between observers. There was no statistically or clinically significant difference between measurements taken with the Luedde as compared with the Hertel instrument. The Luedde exophthalmometer has a number of advantages over the Hertel exophthalmometer, and represents a simple, inexpensive and equally reliable means of evaluating clinically the anteroposterior position of the eye in the orbit.

Aged↗