Biomedical subjects

Donald T Tan

Publications and source records attributed to Donald T Tan.

4 recordsLinked to original sources

PubMed2005

Prevalence of cataract in rural Indonesia.

PURPOSE: To describe the prevalence of cataract in adults in rural Sumatra, Indonesia. DESIGN: Population-based cross-sectional study. PARTICIPANTS: A random sample of all adults aged 21 years or older living in 3 rural villages in central Sumatra was assessed. Nine hundred nineteen of 1089 (84.4%) eligible adults participated. METHODS: A team of 7 ophthalmologists examined the anterior segment of both eyes using a portable slit lamp after pupil dilatation. Lens opacity was graded according to the Lens Opacities Classification System III (LOCS III). A structured questionnaire was used to collect data on education level and income. MAIN OUTCOME MEASURES: Cataract was defined as either a LOCS III nuclear region score of > or =4.0, cortical > or =4.0, or posterior subcapsular (PSC) cataract > or =2.0, in either eye. RESULTS: Two hundred one (21.9%) of 919 subjects were found to have cataract. The age-adjusted prevalence rate of cataract (including cataract surgery) was 23.0% (95% confidence interval, 20.8-25.2). The most common type of cataract for both genders (adjusted for age) was mixed (13%) followed by nuclear only (5.7%), and cortical only (4%). The prevalence rate of any cataract for adults aged 21 to 29 was 1.1%, increasing to 82.8% for those aged older than 60 years. Similar trends with age were noted for nuclear, cortical, and PSC cataract. Women had higher prevalence rates than men for all types of cataract except cortical. There was a trend of increasing prevalence of all types of cataract with decreasing education (P<0.001). CONCLUSIONS: Cataract prevalence in adults aged 21 years and older in rural Indonesia is among the highest reported in Southeast Asia. Despite this, there are inadequate resources available to manage this treatable disease. Allocation of resources to tackle the present burden of cataract would likely have large personal, social, and economic benefits.

Adult↗

PubMed2004

Cataract surgery with the AlphaCor artificial cornea.

PURPOSE: To review the outcomes of AlphaCor artificial cornea (Argus Biomedical Pty Ltd.) implantation concurrent with or subsequent to cataract surgery. SETTING: Nonrandomized multicenter clinical trial. METHODS: AlphaCor devices were implanted under an approved protocol. Extracapsular cataract extraction with intraocular lens implantation was concurrently performed in 5 cases; an additional case had a displaced cataractous lens removed after severe blunt trauma subsequent to AlphaCor implantation. RESULTS: Cataract surgery was difficult because the view was restricted and residual soft lens matter was retained. There was an increased incidence of postoperative complications (eg, melt, glaucoma) in cataract cases compared with noncataract AlphaCor cases. The mean best corrected visual acuity was worse in cases with cataract than in cases without. CONCLUSIONS: The technique for cataract surgery in AlphaCor cases needs to be refined. Imaging studies performed postoperatively may help ascertain whether soft lens matter remains so additional antiinflammatory medication can be considered. Melting appears to be preventable by topical medroxyprogesterone 1% therapy.

Adult↗

PubMed2003

AlphaCor cases: comparative outcomes.

PURPOSE: To describe clinical outcomes after a novel type of corneal surgery, implantation of an artificial cornea, AlphaCor , and to evaluate outcomes in comparison with alternative keratoprostheses and high-risk grafts. METHODS: Case reports and data from a noncontrolled clinical trial and a literature review. RESULTS: The probability of AlphaCor retention to 1 year is 80%. Postoperative best corrected visual acuity ranges from Perception Light to 20/30. The most significant complications are stromal melts and optic depositions, for both of which the main risk factors have been identified. Complications can be managed without loss of the eye. CONCLUSION: Results from the clinical trial period have helped to determine the indications and risk factors for AlphaCor surgery and to refine surgical techniques. Continued monitoring of outcomes as the series increases will allow a more accurate determination of comparative outcomes. The series provides preliminary evidence that AlphaCor may have a lower incidence of complications than traditional keratoprostheses and may prove to be preferable to a donor graft in high-risk cases.

Aged↗

PubMed2002

Outcomes of implantation of an artificial cornea, AlphaCor: effects of prior ocular herpes simplex infection.

PURPOSE: To review outcomes of AlphaCor artificial cornea implantation in patients with and without a history of ocular herpes simplex virus (HSV) and to determine whether herpetic eye disease is an indication for AlphaCor surgery. METHODS: Outcomes of the initial 40 implantations were reviewed and stratified by the presence of a history of ocular disease caused by HSV. Outcomes measures (complications, visual acuity gained) were compared. RESULTS: Eight of the 40 AlphaCor implantations (20%) were in patients with a history of ocular HSV. Six of these eight patients (75%) developed melt-related complications after AlphaCor insertion. Half of the affected patients required removal of the AlphaCor and replacement with a donor corneal graft to restore ocular integrity. In comparison, only six of the 32 (18.8%) patients without HSV developed a melt after AlphaCor insertion. Patients with HSV with devices in situ exhibited a mean loss of 0.3 line of best-corrected visual acuity compared with the preoperative visual acuity, whereas patients without HSV exhibited a mean gain of 1.4 lines of best-corrected visual acuity. CONCLUSIONS: The extensive lamellar corneal surgery involved in AlphaCor implantation may precipitate reactivation of latent HSV such that reactivation and resultant inflammation reduce device biointegration and facilitate melting of corneal stromal tissue anterior to the device. Although there may be some benefit from systemic antiviral medication, the current series is not large enough to demonstrate such a benefit, and melting can occur despite medication. The statistically significant difference in outcomes between recipients of AlphaCor with and without HSV is evidence that a history of HSV should be an exclusion factor for AlphaCor surgery.

Artificial Organs↗