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Biomedical subjects

Jimmy S M Lai

Publications and source records attributed to Jimmy S M Lai.

At least 19 recordsLinked to original sources
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

Corneal injury by wild taro.

We report a case of crystalline keratopathy caused by Alocasia macrorrhiza. The diagnosis was made based on the observation of needle-like crystals in the corneal stroma following injury to that eye. The condition resolved in 3 months with the disappearance of the crystals confirmed by follow-up confocal microscopy.

Alocasia↗
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

Safety of trypan blue 1% and indocyanine green 0.5% in assisting visualization of anterior capsule during phacoemulsification in mature cataract.

PURPOSE: To evaluate the safety of trypan blue 1% and indocyanine green (ICG) 0.5% in assisting visualization of anterior capsule during phacoemulsification in mature cataract. SETTING: Department of Ophthalmology, United Christian Hospital, Hong Kong, China. METHODS: This prospective randomized clinical trial comprised 46 eyes with mature cataract receiving phacoemulsification and posterior chamber intraocular lens implantation. They were randomized into 3 groups (trypan blue, ICG, and control without stain). Visual acuity, endothelial cell count, corneal clarity, anterior chamber reaction, and intraocular pressure (IOP) were documented before surgery and 1 week, 1 month, and 3 months postoperatively. The absolute phaco time was also recorded. RESULTS: There was no significant difference in absolute phaco time (P=.17), mean endothelial cell loss (P=.72 at 1 week, P=.43 at 1 month, and P=.60 at 3 months) and no significant correlation between the absolute phaco time and the change in endothelial cell count (P=.50 at 1 week, P=.10 at 1 month, and P=.60 at 3 months) in the 3 groups. None of the patients had postoperative IOP greater than 21 mm Hg. All eyes had clear corneas and a quiet anterior chamber 3 months after surgery. CONCLUSION: Both trypan blue 1% and ICG 0.5% are safe for assisting visualization of the anterior capsule during phacoemulsification of mature cataract.

Capsulorhexis↗
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

Visual sensation during phacoemulsification and intraocular lens implantation using topical and regional anesthesia.

PURPOSE: To evaluate patients' visual sensations at different stages of phacoemulsification and posterior chamber intraocular lens (PC IOL) implantation under topical and regional anesthesia. SETTING: Department of Ophthalmology, United Christian Hospital and Tseung Kwan O Hospital, Kowloon, Hong Kong, China. METHODS: Seventy-six consecutive patients having phacoemulsification were randomized to a topical anesthesia group (n = 35) or regional anesthesia group (n = 41). The topical anesthesia group received lidocaine hydrochloride 2% gel (Xylocaine) and the regional anesthesia group, a peribulbar or retrobulbar injection of lignocaine 2%. The patients' visual sensations, including light and color sensations, shape of objects, and visual patterns, were evaluated at different stages of surgery. RESULTS: Two patients (4.9%) in the regional anesthesia group and none in the topical anesthesia group experienced total loss of light sensation throughout surgery (P =.50). There was a significant association between color perception and the type of anesthesia at stages 1 and 2 (P<.05) but not at stages 3, 4, and 5 (P>.05). The perception of objects and visual patterns had no association with the type of anesthesia at any stage (P>.05). Of all patients in the study, 56 (73.7%) reported color changes as surgery proceeded. Both groups saw waves, defined as curves with periodic fluctuations in amplitude, at all stages. The perception of some colors and a rectangular moving object was significantly associated with the type of anesthesia at some or all stages (P<.05). CONCLUSIONS: Patients having phacoemulsification and PC IOL implantation under topical or regional anesthesia had a wide spectrum of visual sensations that were similar at most stages of surgery. Patients in the topical anesthesia group perceived more colors at the early stages and more blue throughout surgery than patients in the regional anesthesia group.

Aged↗
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↗
PubMed2003

In vivo confocal microscopy of corneal insect foreign body.

PURPOSE: To report a case of insect corneal foreign body with in vivo confocal microscopy performed. METHODS: Clinical presentation, clinical pictures, and treatment are discussed. Confocal microscopy of the injured cornea was performed in areas showing foreign bodies with and without infiltrations seen under the slit-lamp. CONCLUSION: Confocal microscopy is useful in detection of subtle inflammatory reaction, monitoring the progress of the injury and decision of treatment plans.

Administration, Topical↗