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Biomedical subjects

Clement C Y Tham

Publications and source records attributed to Clement C Y Tham.

At least 19 recordsLinked to original sources
PubMed2006

Microincision bimanual phacotrabeculectomy in eyes with coexisting glaucoma and cataract.

PURPOSE: To report the technique and surgical outcomes of microincision bimanual phacotrabeculectomy in eyes with glaucoma and coexisting cataract. SETTING: Glaucoma Service, Hong Kong Eye Hospital, Hong Kong SAR, China METHODS: Microincision bimanual phacoemulsification with a sleeveless phaco needle and irrigating chopper was performed in combination with trabeculectomy. Phacoemulsification was performed through 2 small clear corneal wounds, sparing the trabeculectomy site from trauma. The intraocular lens (IOL) was then implanted through the trabeculectomy site, so no corneal wound larger than 1.5 mm was required for IOL implantation. RESULTS: The first 10 consecutive eyes of 10 patients who had combined phacotrabeculectomy by a microincision bimanual technique had significantly reduced intraocular pressure. There was a 10.5% reduction in the mean corneal endothelial cell count. There were no other complications up to 6 months after surgery. CONCLUSION: Microincision bimanual phacotrabeculectomy appeared to be an effective and safe option in patients with glaucoma and coexisting cataract.

Aged↗
PubMed2006

The clinical outcomes of cataract extraction by phacoemulsification in eyes with primary angle-closure glaucoma (PACG) and co-existing cataract: a prospective case series.

PURPOSE: To evaluate the clinical outcomes of minimally invasive cataract extraction by phacoemulsification, with primary intraocular lens implantation, in eyes with primary angle-closure glaucoma (PACG) and co-existing cataract. MATERIALS AND METHODS: Consecutive primary angle-closure glaucoma patients with co-existing visually significant cataract were invited to participate in this prospective study. After obtaining informed consent, cataract extraction by phacoemulsification through a clear corneal incision was performed under topical anesthesia. Foldable intraocular lenses were implanted in the same setting. These patients were then followed up for a minimum of 1 year. Outcome measures included intraocular pressure (IOP), requirement for glaucoma drugs, and visual acuity. RESULTS: Twenty-one primary angle-closure glaucoma eyes of 21 patients were recruited. Mean age (+/- SD) was 73.7 +/- 8.1 years (range, 60-87 years). There were 12 female patients and 9 male patients, with 13 right eyes and 8 left eyes. Nine eyes (42.9%) had history of acute primary angle closure. Mean follow-up duration was 20.7 +/- 3.6 months (range, 13-26 months). Intraocular pressure was decreased from a mean preoperative level of 19.7 +/- 6.1 mm Hg (range, 11 mm Hg-40 mm Hg) to 15.5 +/- 3.9 mm Hg (range, 9 mm Hg-26 mm Hg) at final follow-up (P = 0.022) (paired t test). The number of glaucoma eye drops required was decreased from a mean preoperative level of 1.91 +/- 0.77 (range, 1-3) to 0.52 +/- 0.87 (range, 0-3) at final follow-up (P < 0.001) (paired t test). In 10 eyes (47.6%), visual acuity improved significantly after surgery. In 9 eyes (42.9%), visual acuity remained the same. In 2 eyes (9.5%), visual acuity deteriorated significantly after surgery. Mean cup-to-disc ratio was 0.6 +/- 0.2 (range, 0.3-0.9) preoperatively, and 0.7 +/- 0.2 (range, 0.3-0.9) postoperatively (P = 0.047) (paired t test). CONCLUSIONS: In primary angle-closure glaucoma patients with co-existing cataract, cataract extraction alone (by phacoemulsification) can significantly reduce both intraocular pressure and the requirement for glaucoma drugs.

Aged↗
PubMed2006

Comparison of postoperative refractive outcome in phacotrabeculectomy and phacoemulsification with posterior chamber intraocular lens implantation.

PURPOSE: To compare the postoperative refractive outcomes following phacotrabeculectomy and phacoemulsification with posterior chamber intraocular lens implantation. METHODS: A retrospective comparative study of 90 consecutive patients (95 eyes) with cataract with or without co-existing glaucoma who had undergone uncomplicated phacotrabeculectomy or phacoemulsification by a single surgeon. The biometry prediction error was determined for each case by the difference between the actual postoperative refraction and the preoperative predicted refractive outcome, in spherical equivalent. This was followed by a comparative analysis of the mean biometry prediction error, and the number of cases with error >0.50 D or 1.00 D. All biometry measurements were performed by one of the two qualified optometrists. RESULTS: The mean and absolute mean biometry prediction error of the 25 eyes that received phacotrabeculectomy (+0.20 D, absolute error 0.96 D) was comparable to the 70 eyes that received phacoemulsification (-0.14 D, absolute error 0.68 D), P = 0.18 (absolute error, P = 0.12). The proportion of cases with prediction error >0.50 D or 1.00 D was 60% or 40% for phacotrabeculectomy, and 44% or 17% for phacoemulsification, respectively. Phacotrabeculectomy was more likely to have a prediction error >1.00 D (P = 0.02) and a myopic shift of >0.50 D or 1.00 D (P = 0.03 or 0.02, respectively). No significant differences were found with regard to the frequency of hyperopic shift or prediction error >0.50 D. There was no significant difference in either the mean error or the frequency of the different types of error for the different biometry operators, types of glaucoma, or postoperative intraocular pressure control success status. CONCLUSION: Myopically shifted prediction error was significantly more frequent following posterior chamber intraocular lens implantation with phacotrabeculectomy compared with phacoemulsification, even when surgery was uncomplicated and performed by the same surgeon.

Aged↗
PubMed2006

Effect of a previous acute angle closure attack on the corneal endothelial cell density in chronic angle closure glaucoma patients.

PURPOSE: To document the effect of a previous acute angle closure attack on the corneal endothelial cell density in chronic angle closure glaucoma (CACG) patients. METHODS: Consecutive cases of CACG with patent peripheral iridotomy had their central corneal endothelial cell density measured by specular microscopy. The corneal endothelial cell density of those CACG eyes with a previous documented acute angle closure attack were compared with those eyes without such a history, to determine the effect of a previous acute angle closure attack on corneal endothelial cell density. RESULTS: From July 2003 to July 2005, a total of 52 CACG eyes of 52 patients fulfilling the study criteria were recruited. Thirteen eyes (25%) had a previous documented acute angle closure attack, whereas 39 eyes (75%) did not. The mean central corneal endothelial cell density +/-1 standard deviation was 2271.7+/-312.9 (range, 1556 to 2661) cells/mm in those CACG eyes with previous acute angle closure, and 2570.0+/-429.9 (range, 1669 to 3861) cells/mm in those CACG eyes without previous acute angle closure (P < 0.05, Student t test). A previous acute angle closure attack in a CACG eye correlates with a 11.6% reduction in corneal endothelial cell density, compared with a CACG eye without such a history. There were no statistically significant differences between the 2 groups in age, LogMAR visual acuity, intraocular pressure, number of glaucoma eye drops, vertical cup-to-disk ratio, mean deviation or pattern standard deviation in Humphrey automated perimetry (P > 0.05). CONCLUSIONS: A previous acute angle closure attack correlates with a significantly reduced corneal endothelial cell density in CACG patients.

Acute Disease↗
PubMed2006

Scanning laser polarimetry in pulmonary tuberculosis patients on chemotherapy.

INTRODUCTION: The aim of this study was to analyse the thickness of the retinal nerve fibre layer (RNFL) of pulmonary tuberculosis patients on ethambutol and isoniazid. MATERIALS AND METHODS: This was a prospective cohort study where patients with newly diagnosed pulmonary tuberculosis requiring chemotherapy, including ethambutol and isoniazid, were imaged using scanning laser polarimetry. Their mean baseline RNFL thickness and various scanning laser polarimetry parameters of both eyes were measured 2 weeks after the commencement of chemotherapy. The measurements were repeated at 3 months and 6 months after treatment. The various parameters of the baseline and the follow-up measurements were compared using paired sample t-test with Bonferroni correction. RESULTS: Twenty-four patients (16 males and 8 females; mean age, 51.0 +/- 17.6 years) were recruited. There was no statistically significant difference between the baseline and the follow-up measurements in RNFL thickness and all other scanning laser polarimetry parameters. CONCLUSION: In this cohort of subjects, there was no subclinical change in RNFL thickness detected by scanning laser polarimetry in pulmonary tuberculosis patients on chemotherapy, including ethambutol and isoniazid, after 6 months of treatment.

Adult↗
PubMed2005

Changes in the RNFL.

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Antihypertensive Agents↗
PubMed2005

Diode laser transscleral cyclophotocoagulation as primary surgical treatment for medically uncontrolled chronic angle closure glaucoma: long-term clinical outcomes.

PURPOSE: To evaluate the long-term efficacy and safety of diode laser transscleral cyclophotocoagulation as primary surgical treatment of medically uncontrolled chronic angle closure glaucoma. PATIENTS AND METHODS: Thirteen eyes of 13 Chinese patients with medically uncontrolled chronic angle closure glaucoma were treated with diode laser transscleral cyclophotocoagulation between February 2000 and May 2001, and followed up for over 18 months. Post-treatment anti-glaucoma medications were adjusted according to intraocular pressure. If intraocular pressure remained above 21 mm Hg despite medications for more than 4 weeks after cyclophotocoagulation, the procedure was repeated. RESULTS: Mean follow-up +/- SD was 26.5 +/- 4.2 months. Two eyes required repeat cyclophotocoagulation at 6 weeks. Rate of relative success, defined as maintaining an intraocular pressure of 21 mm Hg or below with or without medications, was 92.3% (12 of 13 eyes). Rate of absolute success, defined as maintaining an intraocular pressure of 21 mm Hg or below without medications, was 0% (0 of 13 eyes). Mean +/- SD intraocular pressure was reduced from 36.4 +/- 12.6 mm Hg pre-operatively, to 18.7 +/- 12.2 mm Hg at final follow-up (P = 0.003, paired t test). The mean +/- SD number of intraocular pressure-lowering eye drops was reduced from 2.0 +/- 0.8 pre-operatively, to the lowest point of 0.5 +/- 0.8 at 12 months, and then gradually increased to 2.1 +/- 0.9 at final follow-up. The visual acuity improved after treatment in 2 of 13 eyes (15.4%), remained unchanged in 6 of 13 eyes (46.2%) and deteriorated in 5 of 13 eyes (38.5%). No major complications were encountered. CONCLUSION: Diode laser cyclophotocoagulation appeared to be an effective and safe primary surgical treatment of medically uncontrolled chronic angle closure glaucoma, with intraocular pressure-lowering effect persisting for up to two years.

Aged↗
PubMed2005

Prevalence and mechanism of appositional angle closure in acute primary angle closure after iridotomy.

PURPOSE: A prospective observational case series to assess the prevalence of appositional angle closure in darkness among iridotomized Chinese eyes after acute primary angle closure (APAC) with the use of both clinical methods and ultrasound biomicroscopy. METHODS: Sixteen Chinese patients who had history of APAC and subsequent successful treatment with laser peripheral iridotomy were examined. Fourteen additional control subjects were studied. Gonioscopy and ultrasound biomicroscopic examination were performed in the dark. Gonioscopic appearance of the angle was assessed, and quantitative measurements of the angle from the ultrasound biomicroscopic images were taken. RESULTS: Of the APAC eyes 55.6% had appositionally closed angle clinically and in 38.9% only Schwalbe's line was visible on gonioscopy. Ultrasound biomicroscopy confirmed structurally different anterior segments between eyes with APAC and the control eyes. In particular, the trabecular-ciliary-process distances were markedly different between the two groups. CONCLUSION: This study documented a high prevalence of appositional closure in iridotomized eyes after APAC in Chinese patients. The anteriorly positioned ciliary body, as documented in these cases by ultrasound biomicroscopy, is the likely mechanism of the angle crowding in this patient population.

Acute Disease↗
PubMed2004

Long-term success of argon laser peripheral iridoplasty in the management of plateau iris syndrome.

OBJECTIVE: To document the long-term effect of argon laser peripheral iridoplasty (ALPI) in eyes with plateau iris syndrome. DESIGN: Retrospective, noncomparative, interventional case series. SETTING: New York Eye and Ear Infirmary. METHODS: The charts of all patients with plateau iris syndrome treated with ALPI from 1982 to 1991 and subsequently followed for 6 or more years were retrospectively reviewed. Patients with lens-related mechanisms contributing to angle closure (e.g., phacomorphic or malignant glaucoma) were excluded. MAIN OUTCOME MEASURES: Necessity for repeat ALPI and/or any additional means of intervention. RESULTS: A total of 26 ALPI procedures were performed in 23 eyes of 14 patients (4 men, 10 women). The mean age was 61+/-8.7 years. The mean follow-up was 78.9+/-8.0 months (range, 72-188 months). The angle in 20 of 23 (87.0%) eyes remained open throughout the entire follow-up period after only 1 treatment with ALPI. In 3 eyes, there was gradual reclosure of the angle 5 to 9 years after initial ALPI, but they were readily reopened and maintained open by a single repeat treatment. No filtration surgery was necessary in any eye during follow-up. CONCLUSIONS: ALPI is highly effective in eliminating residual appositional closure after laser iridotomy caused by plateau iris syndrome. The effect is maintained for years, although a small proportion of patients might require retreatment.

Aged↗
PubMed2004

Intraocular pressure profile of a child on a systemic corticosteroid.

PURPOSE: To report the ocular hypertensive response to high-dose systemic corticosteroid in a pediatric patient. DESIGN: Observational case report. METHODS: A 9-year-old patient with leukemia received oral prednisolone at a dosage of 2.3 mg/kg/d for 5 weeks, followed by a 4-month break and then a 4-week course of oral dexamethasone at 10 mg/d. Detailed ocular examination was performed for both eyes before and regularly throughout the two courses of treatment. RESULTS: The intraocular pressure in both eyes rose to almost 40 mm Hg after only 8 days of oral corticosteroid. On stopping systemic corticosteroid, the intraocular pressure rapidly returned to baseline level within 2 days. A similar intraocular pressure profile was recorded for both eyes during the course of oral dexamethasone. The patient remained largely asymptomatic throughout. CONCLUSIONS: Systemic corticosteroid may give rise to significant but asymptomatic ocular hypertension in pediatric patients.

Administration, Oral↗
PubMed2004

Five-year follow up of selective laser trabeculoplasty in Chinese eyes.

PURPOSE: To study the effectiveness and safety of selective laser trabeculoplasty (SLT) on primary open-angle glaucoma and ocular hypertension in Chinese eyes. METHODS: This was a prospective randomized controlled clinical study in which 58 eyes of 29 patients with primary open-angle glaucoma or ocular hypertension were included. One eye of each patient was randomized to receive SLT (Group 1) and the fellow eyes received medical treatment (Group 2). Patients were evaluated after laser treatment at 2 h, 1 day, 1 week, 2 weeks, 1 month, 3 months, 6 months, and then yearly. RESULTS: All patients (13 male, 16 female) were Chinese. The mean age was 51.9 +/- 14.7 years. The mean baseline intraocular pressure was 26.8 +/- 5.6 mmHg in group 1 and 26.2 +/- 4.2 mmHg in group 2 (P = 0.62). The failure rate, defined as intraocular pressure >21 mmHg with maximal medications, was 17.2% in group 1 and 27.6% in group 2 at 5-year follow-up (P = 0.53). Eight eyes (27.6%) in group 1 required medications to control the intraocular pressure to below 21 mmHg. There was no statistically significant difference in the intraocular pressure reductions between the two groups at all time intervals (P > 0.05). The mean number of antiglaucoma medications was significantly lower in the SLT than the medical treatment group up to 5 years of follow up (P < 0.001). Transient post-SLT intraocular pressure spike >5 mmHg was observed in three eyes (10.3%). CONCLUSION: With fewer medications, SLT gives similar intraocular pressure reduction to medical therapy alone in Chinese patients with primary open-angle glaucoma or ocular hypertension.

Asian People↗
PubMed2004

Pressure phosphene self-tonometry: a comparison with goldmann tonometry in glaucoma patients.

PURPOSE: To evaluate whether the pressure phosphene tonometer (PPT) is suitable for self-tonometry in patients with glaucoma or ocular hypertension. METHODS: This was a prospective comparative study of 102 eyes of 102 patients with chronic glaucoma or ocular hypertension. Intraocular pressure (IOP) measurements by the Goldmann tonometer (GT) were compared with self-measured readings with the PPT. Patients evaluated the ease of home use of the PPT. The last 15 patients were asked to stop their glaucoma medications, and the ability of the PPT to detect an elevated IOP during self-tonometry was studied. RESULTS: The mean +/- SD difference between PPT and GT readings was -0.24 +/- 1.57 mm Hg. Comparing the PPT with the GT, 86% of the readings were within +/- 2.0 mm Hg, and 91% were within +/- 3.0 mm Hg. Spearman's correlation coefficient was 0.91. A Bland-Altman plot showed that the 95% limits of agreement between the two methods lay between 2.90 and -3.38 mm Hg. Within-subject coefficients of variation for the GT and the PPT were 4.4% and 7.3%, respectively. In detecting an elevated IOP of more than 21 mm Hg, the sensitivity and the specificity of the PPT were 92.3% and 98.6% respectively. The mean satisfaction score for home use of the PPT was 87.4 +/- 16.3 (maximum 100). CONCLUSIONS: With proper training and technique, self-tonometry with the PPT appears to be accurate up to at least 25 mm Hg and is reproducible. The PPT was sensitive and specific in detecting an elevated IOP of more than 21 mm Hg. As patients were expected to seek ophthalmic care before the self-measured IOP reaches 25 mm Hg, the PPT may have a value for self-monitoring. Patients rated the PPT as satisfactory for home use. Because the PPT is portable and relatively inexpensive and requires no topical anesthesia or direct contact with the eyeball, it may have potential as an instrument for home self-tonometry.

Adult↗
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↗