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Biomedical subjects

Clement C Y Tham

Publications and source records attributed to Clement C Y Tham.

12 recordsLinked to original sources
PubMed2003

Trabeculectomy with beta radiation: long-term follow-up.

PURPOSE: To evaluate the long-term outcome and complications of trabeculectomy with beta radiation. DESIGN: Retrospective noncomparative case series. PARTICIPANTS: Forty-three patients with confirmed primary open-angle glaucoma (POAG), who received trabeculectomy with adjunctive beta radiation at the Prince of Wales Hospital between June 1991 and November 1994. METHODS: Patients fulfilling the preceding criteria were followed up longitudinally. The visual acuity, intraocular pressure (IOP), bleb morphology, and complications were evaluated. MAIN OUTCOME MEASURES: Visual acuity, IOP, bleb morphology, complications. RESULTS: Forty-three eyes of 43 consecutive Chinese patients were recruited and successfully followed up for a minimum of 7 years. The mean age +/- 1 standard deviation (SD) was 60.9 +/- 13.0 years. There were 29 males and 14 females. The mean baseline IOP +/- 1 SD was 28.3 +/- 5.8 mmHg. The mean postoperative IOP +/- 1 SD after the initial trabeculectomy was 11.9 +/- 4.3 mmHg, and the mean number of preoperative IOP-lowering eyedrops +/- 1 SD was reduced from 2.8 +/- 0.5 to 0.7 +/- 1.0 at 7 years follow-up. The qualified success rate at 7 years follow-up, defined as IOP <or=21 mmHg with and without medication(s), was 88.4%. The complete success rate at 7 years defined as IOP <or=21 mmHg without medication was 60.7%. Two eyes developed blebitis, and one of them progressed to corneal decompensation after the infection. One eye had hypotony, and one eye had a traumatic ruptured bleb. Twelve eyes (27.9%) developed significant cataract. No corneal ulceration or scleral necrosis was encountered. CONCLUSIONS: From this noncomparative study, trabeculectomy with a single dose of 1000 rad beta radiation used as an adjunctive measure for POAG in Chinese eyes had achieved a qualified success rate of 88.4% at 7 years.

Adult↗
PubMed2003

Diode laser transscleral cyclophotocoagulation in the treatment of chronic angle-closure glaucoma: a preliminary study.

PURPOSE: To evaluate the efficacy and safety of diode laser transscleral cyclophotocoagulation in the treatment of chronic angle-closure glaucoma. PATIENTS AND METHODS: A prospective, non-comparative interventional pilot study was conducted. Fourteen eyes of 14 Chinese patients with chronic angle-closure glaucoma whose intraocular pressures were greater than 21 mm Hg on medications were treated with diode laser transscleral cyclophotocoagulation using the G-probe at the United Christian Hospital between February 2000 and May 2001. The inferior 270 degrees quadrant (from 2 to 11 o'clock for right eye and from 1 to 10 o'clock for left eye) was treated and the patients were followed up regularly. The initial laser energy was set at 2,000 mWatt with a duration of 2 seconds. The post-treatment anti-glaucoma medications were adjusted according to the intraocular pressure. If medications failed to lower the intraocular pressure to below 21 mm Hg, cyclophotocoagulation to the same inferior 270 degrees quadrant was repeated. RESULTS: All patients completed a 12-month follow-up period. The total success rate defined as IOP < 21 mm Hg with or without medication(s) was 85.7% at 1 year of follow-up review. The mean +/- SD intraocular pressure decreased from pre-treatment level of 36.9 +/- 11.7 mm Hg to 18.9 +/- 6.5 mm Hg at 1 year after treatment. The difference was statistically significant (P < 0.001) (Paired t test). The mean +/- SD number of IOP-lowering eyedrops was significantly reduced from 1.9 +/- 0.7 before cyclophotocoagulation to 0.4 +/- 0.8 at 1 year after treatment (P = 0.0002) (Paired t test). Two eyes required repeat treatment. Seven eyes (50%) had atonic pupil following the laser treatment. CONCLUSION: Diode laser transscleral cyclophotocoagulation is effective in lowering the intraocular pressure in chronic angle-closure glaucoma and its effect lasts for at least 1 year.

Aged↗
PubMed2003

Different optineurin mutation pattern in primary open-angle glaucoma.

PURPOSE: The optineurin gene (OPTN) is the second gene besides MYOC in which mutations have been identified to be associated with primary open-angle glaucoma (POAG). In this study, sequence alterations in the OPTN gene associated with POAG in Chinese subjects were investigated. METHODS: All the coding exons of OPTN were screened, including the intron-exon boundaries, for sequence alterations in a Chinese sample of 119 sporadic patients with POAG and 126 unrelated control subjects by polymerase chain reaction-conformation-sensitive gel electrophoresis and DNA sequencing. RESULTS: Sixteen sequence changes were identified: 3 had been reported (T34T, M98K, and R545Q) and 13 were novel (T49T, E103D, V148V, P199P, T202T, H486R, IVS6-5T-->C, IVS6-10G-->A, IVS7+24G-->A, IVS8+20G-->A, IVS13+21C-->G, IVS15+10G-->A, and IVS15-48C-->A). Among them, only E103D, H486R, V148V, and IVS13+21C-->G were found exclusively in patients with POAG, whereas P199P, T202T, and IVS8+20G-->A were present only in control subjects. The genotype of IVS7+24G-->A showed a significant association with POAG (P = 0.02, Fisher two-tailed exact test) and with and increased cup-to-disc ratio in these patients (P = 0.005, Mann-Whitney test). CONCLUSIONS: The findings in the current study enrich the evidence on the OPTN gene as a causative gene for POAG and suggest a different mutation pattern of OPTN in Chinese than in whites. The wide spectrum of putative mutations detected in this study suggests that both structural and functional disruptions in OPTN may contribute to the pathogenesis of glaucoma.

Adolescent↗
PubMed2002

Efficacy and safety of immediate anterior chamber paracentesis in the treatment of acute primary angle-closure glaucoma: a pilot study.

OBJECTIVE: To study the safety and effectiveness of immediate anterior chamber paracentesis, combined with antiglaucomatous medications, in the intraocular pressure control and relief of symptoms of acute primary angle-closure glaucoma (PACG). DESIGN: Prospective noncomparative case series. PARTICIPANTS: Eight consecutive patients with their first attack of acute PACG, with intraocular pressure > or =50 mmHg, were recruited into the study. INTERVENTION: On presentation, each patient received topical pilocarpine (4%) and timolol (0.5%), immediate anterior chamber paracentesis, and systemic acetazolamide and mannitol as primary treatment. The intraocular pressures at 15 and 30 minutes, and then at 1, 2, 3, 12, and 24 hours, were documented by applanation tonometry. MAIN OUTCOME MEASURES: Symptoms, visual acuity, intraocular pressure, corneal edema, angle status on gonioscopy, pupillary size, and reaction. RESULTS: Ten eyes of eight patients seen with acute PACG were recruited. The mean intraocular pressure was reduced from 66.6 +/- 9.1 mmHg to 15.1 +/- 3.5 mmHg immediately after paracentesis, and then to 17.1 +/- 7.0 mmHg at 15 minutes, 21.7 +/- 10.2 mmHg at 30 minutes, 22.7 +/- 11.0 mmHg at 1 hour, and 20.1 +/- 14.6 mmHg at 2 hours after paracentesis. The mean intraocular pressure was less than 21 mmHg at 2 hours and beyond. There was instant symptomatic relief for all patients. No complications from the paracentesis were encountered. CONCLUSIONS: From this preliminary study, immediate paracentesis seems to be safe and effective in controlling the intraocular pressure and eliminating symptoms in acute PACG.

Acetazolamide↗
PubMed2002

Argon laser peripheral iridoplasty versus conventional systemic medical therapy in treatment of acute primary angle-closure glaucoma : a prospective, randomized, controlled trial.

OBJECTIVE: To study whether argon laser peripheral iridoplasty (ALPI) is as effective and safe as conventional systemic medications in treatment of acute primary angle-closure glaucoma (PACG) when immediate laser peripheral iridotomy is neither possible nor safe. DESIGN: Prospective, randomized, controlled trial. PARTICIPANTS: Seventy-three eyes of 64 consecutive patients with their first presentation of acute PACG, with intraocular pressure (IOP) levels of 40 mmHg or more, were recruited into the study. INTERVENTION: The acute PACG eye of each consenting patient received topical pilocarpine (4%) and topical timolol (0.5%). The patients were then randomized into one of two treatment groups. The ALPI group received immediate ALPI under topical anesthesia. The medical treatment group was given 500 mg of intravenous acetazolamide, followed by oral acetazolamide 250 mg four times daily, and an oral potassium supplement until IOP levels normalized. Intravenous mannitol also was administered to the latter group if the presenting IOP was higher than 60 mmHg. The acute PACG eye of both groups continued to receive topical pilocarpine (1%) until peripheral iridotomy could be performed. MAIN OUTCOME MEASURES: Intraocular pressure profile, corneal clarity, symptoms, visual acuity, angle status by indentation gonioscopy, and complications of treatment. RESULTS: Thirty-three acute PACG eyes of 32 patients were randomized to receive immediate ALPI, whereas 40 acute PACG eyes of 32 patients had conventional systemic medical therapy. Both treatment groups were matched for age, duration of attack, and IOP at presentation. The ALPI-treated group had lower IOP levels than the medically treated group at 15 minutes, 30 minutes, and 1 hour after the start of treatment. The differences were statistically significant. The difference in IOP levels became statistically insignificant from 2 hours onward. The duration of attack did not affect the efficacy of ALPI in reducing IOP in acute PACG. No serious laser complications occurred, at least in the early postlaser period. CONCLUSIONS: Argon laser peripheral iridoplasty significantly is more effective than conventional systemic medications in reducing IOP levels in acute PACG in eyes not suitable for immediate laser peripheral iridotomy within the first 2 hours from the initiation of treatment. Argon laser peripheral iridoplasty is a safe and more effective alternative to conventional systemic medications in the management of acute PACG not amenable to immediate laser peripheral iridotomy.

Acetazolamide↗
PubMed2002

Traumatic subluxation causing variable position of the crystalline lens.

We present a case of traumatic lens subluxation that was evident only when the patient was in the supine position. This case illustrates that a crystalline lens with traumatic zonular rupture can change its position depending on the posture of the patient. If such a lens is suspended by the remaining zonules at the superior quadrant while the patient is erect, phacodonesis may be present while the lens remains in its normal position. However, when the patient is in the supine position, the lens drops back into the vitreous cavity. Examination in erect and supine positions is important in the preoperative assessment of patients with traumatic phacodonesis or iridodonesis.

Aged↗
PubMed2002

Physical effects of reuse and repeated ethylene oxide sterilization on transscleral cyclophotocoagulation laser G-probes.

PURPOSE: The authors documented the physical effects of reuse and repeated ethylene oxide sterilization on transscleral cyclophotocoagulation laser G-probes. METHODS: Transscleral cyclophotocoagulation was performed using G-probes on fresh porcine eyes. Each of two G-probes was used for four transscleral cyclophotocoagulation procedures, with three cycles of ethylene oxide sterilization in between. The power output from the G-probes was measured by a laser output meter before and after each transscleral cyclophotocoagulation procedure. The G-probes were also examined under a slit lamp for signs of physical damage. RESULTS: Repeated use of the G-probe in transscleral cyclophotocoagulation, with ethylene oxide sterilization in between, resulted in an average decrease of 3% in laser energy delivered per repeated cycle of use up to the fourth cycle. No signs of physical damage were found. CONCLUSIONS: Laser G-probes remain functional after repeated use and ethylene oxide resterilization for up to four cycles. No visible physical damage to the probes was identified. It is safe and cost-effective to reuse G-probe for transscleral cyclophotocoagulation with ethylene oxide sterilization, provided the surgeon stays alert for signs of probe damage. This alertness should be retained regardless of whether new or old G-probes are used.

Animals↗
PubMed2002

Topical anesthesia in phacotrabeculectomy.

PURPOSE: To study the safety and efficacy of topical anesthesia alone, without systemic sedation, in phacotrabeculectomy for cataract and primary open-angle glaucoma. METHODS: In this prospective study, topical anesthesia with 2% lidocaine hydrochloride jelly without systemic sedation was used for combined phacoemulsification, posterior chamber intraocular lens implantation, and trabeculectomy in consecutive patients with primary open-angle glaucoma and concurrent cataract at the United Christian Hospital, Kowloon, Hong Kong, from September 2000 to May 2001. Visual analog pain score and change in vital signs were used to assess the intraoperative pain experience. Other outcome measures included postoperative visual acuity and intraocular pressure at 3 months. RESULTS: Twenty-two eyes of 22 consecutive patients were included in the study. The mean intraoperative pain score was 0.9 (range, 0-3). Three patients reported discomfort intraoperatively. No injection of supplementary anesthetic was required in any of the eyes. None of the patients had significant increase of pulse rate or blood pressure during the whole surgical procedure. Six patients required oral analgesic for postoperative discomfort. The mean preoperative medically treated IOP was 20.3 +/- 5.9 mm Hg and the mean postoperative IOP at 3 months was 14.4 +/- 4.7 mm Hg. All except two patients had improved visual acuity. There was no serious intraoperative or postoperative complication. CONCLUSION: Topical 2% lidocaine hydrochloride jelly without systemic sedation may be a safe and effective anesthetic method in phacotrabeculectomy for patients with primary open-angle glaucoma with coexisting cataract.

Aged↗
PubMed2002

Laser peripheral iridoplasty as initial treatment of acute attack of primary angle-closure: a long-term follow-up study.

PURPOSE: To study the long-term clinical course and complications of patients with acute primary angle-closure treated with immediate laser peripheral iridoplasty followed by laser peripheral iridotomy. PATIENTS AND METHODS: Consecutive patients with acute primary angle closure treated with immediate laser peripheral iridoplasty, followed by laser peripheral iridotomy, at the Prince of Wales Hospital from July 1997 through January 2000 were followed up to document the clinical course of their disease and any complications from the laser treatment. Visual acuity, intraocular pressure, gonioscopic findings, corneal and lens clarity, iris appearance, pupillary reaction, and progression of glaucomatous optic neuropathy were evaluated. RESULTS: Thirty eyes of 29 Chinese patients with acute primary angle closure treated initially with either argon or diode laser peripheral iridoplasty were recruited. The mean follow-up period was 33.0 +/- 9.3 months. Twenty-one eyes (70%) had no further attack and maintained normal intraocular pressure without medications, and 9 eyes (30%) developed chronic angle-closure glaucoma with peripheral anterior synechiae. All eyes had pigmented laser marks on the peripheral iris, but none had peripheral corneal burn. CONCLUSIONS: Long-term follow-up data indicated that 30% of Chinese eyes with acute primary angle closure successfully treated with immediate laser peripheral iridoplasty followed by laser peripheral iridotomy developed peripheral anterior synechiae and an increase in intraocular pressure. There were minimal long-term complications on the cornea and the lens from the laser treatment.

Acute Disease↗
PubMed2002

Intracameral lidocaine in trabeculectomy. A preliminary safety and efficacy study.

PURPOSE: To study the safety and efficacy of intracameral lidocaine as anaesthesia in trabeculectomy for primary open-angle glaucoma. METHODS: Trabeculectomy under intracameral anaesthesia using 1% preservative-free lidocaine was performed in 10 patients with primary open-angle glaucoma. Intraoperative pain score, postoperative intraocular pressure (IOP) and endothelial cell count at 3 months were recorded. RESULTS: The mean pain score was 1.70 +/- 1.34. The mean IOP was lowered from 24.60 +/- 8.28 mmHg preoperatively to 14.1 +/- 3.11 mm Hg postoperatively. There was no significant decrease in the mean endothelial cell count 3 months after the surgery (P = 0.375). CONCLUSION: Intracameral lidocaine may be a safe and effective alternative anaesthesia method in trabeculectomy for uncomplicated primary open-angle glaucoma.

Aged↗