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T Y Y Lai

Publications and source records attributed to T Y Y Lai.

At least 19 recordsLinked to original sources
PubMed2006

Peripheral and posterior pole retinal lesions in association with high myopia: a cross-sectional community-based study in Hong Kong.

PURPOSE: To evaluate the prevalence and factors associated with posterior pole and peripheral retinal lesions in Chinese subjects with high myopia. METHODS: Three hundred and thirty-seven asymptomatic adults with high myopia of refractive error <or=-6 D were examined in a cross-sectional community-based study. All subjects underwent cycloplegic refraction, ultrasound biometry and dilated fundal examination. Statistical analysis was performed to assess factors associated with the presence of posterior pole and peripheral retinal lesions. RESULTS: The mean age of the 337 subjects was 36.0 years and the mean spherical equivalent refractive error was -10.2 D. Thirty-eight eyes (11.3%, 95% CI=8.1-15.2%) were found to have one or more posterior pole lesions and subjects with posterior pole lesion had significantly older age, longer axial length and higher degree of myopia (all P<0.001) compared with subjects without posterior pole lesion. After controlling for axial length, both the severity of refractive error and older age were significantly associated with the presence of posterior pole lesion (both P<0.001). For peripheral retinal lesions, 189 eyes (56.1%, 95% CI=50.6-61.5%) were found to have one or more peripheral retinal lesions. The presence of peripheral retinal lesion was associated with younger age and higher degree of refractive error (P=0.046 and 0.002, respectively). CONCLUSION: Posterior pole and peripheral retinal degenerative lesions were found in a considerable proportion of subjects with high myopia. As some of these retinal lesions might predispose to visual impairment, highly myopic individuals should be educated on the symptoms of various eye conditions and seek care immediately if symptoms arise.

Adolescent↗
PubMed2006

Decreasing efficacy of repeated intravitreal triamcinolone injections in diabetic macular oedema.

BACKGROUND/AIM: Intravitreal triamcinolone (IVTA) results in transient improvements in diabetic macular oedema (DMO), necessitating repeated injections. The authors report a case series of 10 eyes of 10 patients with DMO, who received a repeat injection of 4 mg IVTA, at least 26 weeks after the first injection of the same dose. METHOD: Pre-injection and at 2, 4, 9, and 17 weeks post-injection, best corrected visual acuity (BCVA) and central foveal thickness (CFT) on optical coherence tomography, after the first and repeat injections, were compared using paired t test. Side effects were monitored. RESULTS: BCVA, CFT, intraocular pressure (IOP), and cataract scores were not significantly different before initial and repeat injections (given at 32.5 (SD 3.5) weeks after the first injection). Transient improvements of BCVA and CFT were achieved after both injections. However, after the repeat injection, the BCVA was significantly worse at all time points (p<0.05) and so were the best achieved CFT and the CFT at 4 weeks post-injection (p = 0.034 and 0.011 respectively), compared with the initial injection. Post-injection maximum IOPs and increase in cataract scores were not significantly different between the two injections. CONCLUSION: A repeat injection of 4 mg of IVTA may not be as effective as an initial injection for the treatment of DMO.

Aged↗
PubMed2006

Safety enhanced photodynamic therapy with half dose verteporfin for chronic central serous chorioretinopathy: a short term pilot study.

AIM: To evaluate short term safety of an enhanced photodynamic therapy (PDT) protocol with half dose verteporfin for treating chronic central serous chorioretinopathy (CSC). METHODS: 20 eyes of 18 patients with symptomatic chronic CSC underwent PDT using 3 mg/m2 verteporfin. Verteporfin was infused over 8 minutes followed by indocyanine green angiography guided laser application 2 minutes later. Serial optical coherence tomography (OCT) and multifocal electroretinography (mfERG) recordings were performed before PDT, at 4 days, 2 weeks, and 1 month after PDT. The best corrected visual acuity (BCVA), OCT central retinal thickness, and mean mfERG response amplitudes and peak latencies were compared longitudinally. Subgroup analysis was further performed for eyes with or without pigment epithelial detachment (PED). RESULTS: At 1 month after PDT, the median BCVA improved from 20/40 to 20/30 (p = 0.001). The mean central retinal thickness also reduced from 276 microm to 158 microm (p < 0.001) and 17 (85%) eyes had complete resolution of serous retinal detachment and/or PED. MfERG showed no significant changes in the mean N1 and P1 response amplitude and latency for all eyes. Subgroup analysis demonstrated that eyes without PED had a significant increase in the mean central mfERG P1 response amplitude with reduction in P1 peak latency at 1 month post-PDT. For eyes with PED, transient reduction in the mean central P1 response amplitude was observed at 4 days post-PDT. CONCLUSIONS: The modified safety enhanced PDT protocol with half dose verteporfin appeared to be a beneficial treatment option for patients with chronic CSC, especially in eyes without serous PED. Further controlled study is warranted to demonstrate the long term safety and efficacy of this treatment option.

Adult↗
PubMed2006

Retinal ganglion cells toxicity caused by photosensitising effects of intravitreal indocyanine green with illumination in rat eyes.

AIM: To investigate the effects of indocyanine green (ICG) with or without illumination on rat retinal ganglion cells (RGC) and retinal morphology. METHODS: Intravitreal injections of 1.0 mg/ml ICG solution were performed in rat eyes with or without subsequent illumination for 5 minutes. Eyes in the control group had intravitreal injections of balanced salt solution with illumination. Retrograde labelling of RGC with 6% Fluoro-Gold was performed 1 month later and RGC densities were compared between the three groups. Light microscopy with measurements of outer nuclear layer (ONL) and inner nuclear layer (INL) thicknesses were also performed and compared. RESULTS: Eyes with ICG without illumination showed insignificant reduction in RGC density compared with the control group (p = 0.28), whereas a significant decrease in RGC density was found in eyes that had ICG injection with illumination (p = 0.036). A significant increase in ONL thickness was also observed in the ICG with illumination treated eyes compared with the ICG without illumination and the control groups (p<0.001). No significant difference in INL thickness was observed between the three groups. CONCLUSIONS: Intravitreal injection of 0.1 mg/ml ICG in rat eyes followed by illumination resulted in photosensitising toxicity to RGC. Lower ICG concentration or illumination level should be considered when performing ICG assisted macular surgery.

Animals↗
PubMed2006

Combined photodynamic therapy and intravitreal triamcinolone injection for the treatment of subfoveal choroidal neovascularisation in age related macular degeneration: a comparative study.

AIM: To evaluate the outcomes of combined intravitreal triamcinolone (IVTA) and photodynamic therapy (PDT) with verteporfin in the treatment of subfoveal choroidal neovascularisation (CNV) caused by age related macular degeneration (AMD). METHODS: 48 eyes from 48 patients with subfoveal CNV caused by AMD were prospective recruited, with 24 eyes treated with combined PDT with IVTA and compared with a control group of 24 eyes which received PDT monotherapy. In the combined treatment group, IVTA was performed immediately after PDT as an outpatient procedure. The mean number of treatments, mean logMAR best corrected visual acuity (BCVA), mean line of visual acuity changes, and proportion of patients without moderate visual loss at 1 year were compared between the combined and monotherapy groups. RESULTS: At 1 year the logMAR BCVA for the PDT with IVTA group changed from 0.88 to 0.95 (p = 0.32 compared with baseline), whereas the logMAR BCVA for the monotherapy group reduced from 0.74 to 1.09 (p<0.001 compared with baseline). A significantly higher proportion of patients who had PDT with IVTA did not develop moderate visual loss at 1 year compared with the monotherapy group (70.8% and 33.3% respectively, p = 0.009). Eyes which had combined treatment had significantly fewer lines lost compared with monotherapy alone (0.7 and 3.5 lines respectively, p = 0.015). Subgroup analysis showed that PDT with IVTA is effective in preventing visual loss in both predominately classic and occult CNV groups. The mean number of treatments for the combined and monotherapy groups was 1.5 and 1.96 respectively (p = 0.076). CONCLUSIONS: Combined PDT with IVTA appeared more effective statistically at 12 months for stabilisation of vision (<3 logMAR lines change) compared with PDT monotherapy. Further randomised control trials might be justified to conclude the efficacy of PDT with IVTA.

Aged↗
PubMed2005

A prospective study on trypan blue capsule staining under air vs under viscoelastic.

AIM: To compare the safety and effectiveness of trypan blue capsule staining under air vs under viscoelastic. METHODS: A total of 52 consecutive patients planned for phacoemulsification of white mature cataract were randomly assigned to trypan blue staining under air or under viscoelastic. Perioperative changes in best-corrected visual acuity (BCVA), central corneal thickness (CCT), and endothelial cell density (ECD) were compared between the two groups. The differences in operating and phacoemulsification times, staining pattern, and complications between the two groups were also recorded. RESULTS: Phacoemulsification of white mature cataract was performed in 50 (96%) eyes. The median preoperative BCVA was hand movement. No significant differences in the baseline characteristics were found between the two groups. At 3 months after phacoemulsification, the median BCVA improved to 0.8. The mean CCT returned to preoperative level by 1 month postoperatively and the mean ECD loss was 11.9% 3 months postoperatively. No significant differences in median BCVA, mean phacoemulsification and operation times, mean CCT, and mean ECD were found between the two groups. CONCLUSIONS: Trypan blue staining of the anterior lens capsule under air or under viscoelastic were similarly effective and safe methods for the phacoemulsification of white mature cataract.

Aged↗
PubMed2005

Phacoemulsification with intravitreal triamcinolone in patients with cataract and coexisting diabetic macular oedema: a 6-month prospective pilot study.

AIMS: To assess the safety and efficacy of phacoemulsification with intravitreal triamcinolone (ivTA) injection in diabetics with cataract and clinically significant macular oedema (CSMO). METHODS: A total of 19 eyes of 15 consecutive diabetic patients with cataract and CSMO were prospectively recruited. Patients underwent phacoemulsification and intraocular lens implantation with 4 mg ivTA injection at completion of surgery. Patients were followed up on day 1, then weekly for 1 month, and thereafter monthly until 6 months postoperatively. Best corrected visual acuity (BCVA), central macular thickness (CMT) measured by optical coherence tomography, and adverse events were recorded. RESULTS: In total, 17 eyes completed 6 months of follow-up. In all, 58.8% showed improvement in BCVA of >or=2 lines, with statistically significant improvement in mean Snellen BCVA of 2.4 lines at 6 months. The peak BCVA was achieved at 4 months. The mean CMT decreased from a baseline of 449 microm to a minimum of 321+/-148 microm (28.5% reduction) achieved at 2 months, with statistically significant reduction at all postoperative time intervals until 6 months. Of 17 eyes, 4 (23.5%) developed transiently elevated intraocular pressure that normalised by 6 months in all but one patient. No injection- or surgery-related complications were encountered. CONCLUSIONS: Phacoemulsification with concurrent 4 mg ivTA injection appears to be a safe option for managing diabetics with cataract and CSMO. However, large-scaled randomised controlled trials are necessary for delineating the relative contributions of cataract removal and CMT reduction to visual improvement. Moreover, the transient effect on CMT may warrant further studies to determine optimal timing and dosage of further ivTA injections.

Aged↗
PubMed2005

Immediate pars plana vitrectomy for dislocated intravitreal lens fragments during cataract surgery.

PURPOSE: To assess the outcome of patients who underwent instantaneous pars plana vitrectomy for dislocated lens fragments during cataract surgery. METHODS: The medical records of 29 patients who underwent immediate pars plana vitrectomy for dislocated lens fragments at the same sitting of phacoemulsification surgery were reviewed. Data including patients' demographics, preoperative and postoperative vision, risk factors for lens fragment dislocation, and intraoperative and postoperative complications were recorded. RESULTS: The mean follow-up period of the patients was 12.3 months (range, 3-47 months). The median preoperative visual acuity was 6/90 (range, LP to 6/15). The median final postoperative visual acuity was 6/18 (range, NLP to 6/9) and the mean improvement in vision after the operation was 4.5 lines. The commonest risk factors for dislocation of lens fragment were late detection of posterior capsule tear, splitting of anterior capsulorrhexis, and hard nucleus. After excluding nine eyes with other pre-existing ocular comorbidities, 10 (50%) eyes had a final visual acuity of 6/12 or better. Complications after surgery included three (10%) cases of retinal detachment and one (3%) patient developed epiretinal membrane. None of the patients in the study developed secondary glaucoma or cystoid macular oedema following surgery. CONCLUSION: Immediate vitrectomy in the same sitting of the cataract surgery is a surgical option in the management of dislocated intravitreal lens fragments when vitreoretinal support is available. Most patients achieve a good visual outcome with reduced risk of secondary glaucoma and cystoid macular oedema after surgery.

Aged↗
PubMed2005

The effects of indocyanine green and endoillumination on rabbit retina: an electroretinographic and histological study.

AIM: To evaluate the functional and morphological retinal toxicity associated with intravitreal injection of indocyanine green (ICG) dye in rabbit eyes during vitrectomy with endoillumination. METHODS: 20 eyes of 10 New Zealand pigmented rabbits were used in the study. All eyes underwent pars plana vitrectomy and removal of posterior vitreous cortex under endoillumination. In one eye of each rabbit, intravitreal injection of 0.1 ml of 2.5 mg/ml ICG was applied for 30 seconds followed by 10 minutes of endoillumination. The control eye had endoillumination only without ICG injection. Dark adapted and light adapted electroretinograms (ERGs) were performed before the surgery and 1 week after surgery for serial comparisons. Rabbits were killed 1 week after surgery and eyes were enucleated for histological examination. RESULTS: Serial ERG comparisons showed significant reduction in the light adapted a-wave amplitude (p = 0.037) and significant delays in the dark adapted and light adapted b-wave latencies (p = 0.020 and p = 0.038, respectively) in the ICG treated eyes. Histological examinations demonstrated loss of photoreceptor outer segments with focal absence of photoreceptors in some areas in the ICG injected eyes. CONCLUSIONS: Vitrectomy followed by intravitreal injection of 2.5 mg/ml ICG for 30 seconds with endoillumination may result in retinal toxicity causing functional and morphological retinal damages in rabbit eyes. The lowest concentration of ICG should be used if necessary for intraocular use to prevent potential retinal toxicity.

Animals↗
PubMed2005

Vitrectomy and gas tamponade without internal limiting membrane peeling for myopic foveoschisis.

AIM: To evaluate the clinical and anatomical outcomes of pars plana vitrectomy and gas tamponade without internal limiting membrane (ILM) peeling in symptomatic patients caused by myopic foveoschisis. METHODS: Nine eyes in eight highly myopic patients who had myopic foveoschisis with foveal detachment underwent vitrectomy without ILM peeling followed by gas tamponade. Main outcome measures include change in best corrected visual acuity (BCVA) and changes in height of the foveal detachment and resolution of the myopic foveoschisis measured by optical coherence tomography (OCT). RESULTS: After surgery, BCVA improved in eight eyes with the median BCVA improved from 20/80 to 20/50 (p=0.012). The mean line of visual improvement was 3.6 lines. OCT showed complete resolution of myopic foveoschisis with complete foveal reattachment in seven (77.8%) eyes with partial resolution in two (22.2%) eyes. The mean height of foveal detachment decreased from 505 mum preoperatively to 21 mum postoperatively (p<0.001). CONCLUSIONS: Vitrectomy without ILM peeling followed by gas tamponade appeared to result in favourable visual and anatomical outcomes for treating myopic foveoschisis in highly myopic eyes. The results are comparable with studies in which ILM removal was performed. Further controlled study will be useful to determine the role of ILM peeling in these patients.

Adult↗
PubMed2005

Choroidal neovascularisation in pathological myopia: an update in management.

Choroidal neovascularisation (CNV) secondary to pathological myopia is an important cause of significant visual impairment in young and middle aged adults globally and is particularly prevalent in Asian populations. In the past few years, there have been rapid advancements in the different treatments for myopic CNV. The purpose of this perspective is to give an overview of the natural history of myopic CNV and the various treatment options including laser photocoagulation, photodynamic therapy, sub-macular surgery, and macular translocation surgery. Future directions in the management of myopic CNV are also discussed.

Choroidal Neovascularization↗
PubMed2005

Causes of childhood blindness in a school for the visually impaired in Hong Kong.

OBJECTIVE: To identify the causes of blindness in children attending a school for the blind in Hong Kong. DESIGN: Cross-sectional observational study. SETTING: School for blind children in Hong Kong. PARTICIPANTS: Eighty-two blind students at the Ebenezer School and Home for the Visually Impaired were examined between December 1998 and August 1999. MAIN OUTCOME MEASURES: Demographic data were obtained from students and a questionnaire assessment made of their medical and ocular history. Visual acuity was assessed and visual loss classified according to the World Health Organization classification of visual impairment. Complete ophthalmic assessments were performed in all students including slit-lamp examination and dilated binocular indirect ophthalmoscopy. RESULTS: The mean age of the students was 12.2 years. Ten (12.2%) had a family history of eye disease. Major past medical illnesses were reported in 50% with prematurity and diseases of the central nervous system found in 26.8% and 11.0% of students, respectively. The most common anatomical site for visual impairment was the retina (47.6%), followed by diseases of the optic nerve (14.6%), and diseases of the anterior segment and the lens (14.6%). CONCLUSIONS: The pattern of childhood blindness in Hong Kong is similar to that seen in other developed countries. Preventable causes of childhood blindness, such as prematurity and birth asphyxia, were responsible for a large proportion of cases. Early diagnosis and treatment of such conditions may reduce the incidence of childhood blindness in Hong Kong.

Adolescent↗
PubMed2005

Idiopathic macular hole surgery in Chinese patients: a randomised study to compare indocyanine green-assisted internal limiting membrane peeling with no internal limiting membrane peeling.

OBJECTIVE: To compare the anatomical and visual outcomes of primary idiopathic macular hole surgery using indocyanine green-assisted internal limiting membrane peeling versus no internal limiting membrane peeling. DESIGN: Prospective randomised controlled clinical trial. SETTING: University teaching hospital, Hong Kong. PATIENTS: Fifty-one eyes of 49 Chinese patients with primary idiopathic macular hole were studied. INTERVENTIONS: Patients were randomised to undergo pars plana vitrectomy with indocyanine green-assisted internal limiting membrane peeling (26 eyes) or surgery without internal limiting membrane peeling (25 eyes). Perfluorocarbon gas was used in all cases as internal tamponade. MAIN OUTCOME MEASURES: Primary macular hole closure rate and best-corrected visual acuity. RESULTS: The mean follow-up duration was 12 months (range, 6-23 months). Respectively to the indocyanine green-assisted internal limiting membrane peeling group and non-internal limiting membrane peeling group, the primary anatomical closure rate was 92.3% and 32.0% (P<0.001), whereas improvement in best-corrected visual acuity was 3.7 and 1.5 lines (P=0.002). More eyes in the first group (84.6%) had improvement of 2 or more lines of best-corrected visual acuity after surgery than in the second group (32.0%) [P<0.001]. Multivariate logistic regression showed indocyanine green-assisted internal limiting membrane peeling was the only significant predictor for primary closure of the macular hole (adjusted odds ratio=30.8). CONCLUSION: Indocyanine green-assisted internal limiting membrane peeling in idiopathic macular hole surgery results in significantly better anatomical and visual outcomes compared with non-internal limiting membrane peeling in Chinese patients.

Adolescent↗
PubMed2004

Trypan blue- and indocyanine green-assisted epiretinal membrane surgery: clinical and histopathological studies.

PURPOSE: To evaluate the clinical outcome and electron microscopic findings of trypan blue (Tb) and indocyanine green (ICG) assisted epiretinal membrane (ERM) surgery. METHODS: This is a prospective consecutive noncomparative interventional case series. After pars plana vitrectomy, 0.1 ml of 0.6 mg/ml Tb solution was applied for 1 min under air for ERM staining. After ERM removal, internal limiting membrane (ILM) was further peeled after staining with 0.2 ml of 1 mg/ml ICG solution. Intraoperative specimens were sent for electron microscopy. Tb was considered useful if the edge of ERM was stained where peeling could be initiated with a clearer visualisation of the overall extent of the ERM. RESULTS: In all, 16 eyes from 16 patients were recruited. There were nine grade 1 ERMs, five grade 2 ERMs, and two grade 3 ERMs. Tb was useful in six (67%) of the nine eyes with grade 1 ERMs and in all eyes with grade 2 or 3 ERMs. The three remaining grade 1 ERMs were removed together with surrounding ILM that was stained by ICG. The mean line of improvement was 1.3 lines with the median BCVA improved from 6/12 to 6/9. All 16 eyes had symptomatic improvement and none developed ERM recurrence. No complication related to Tb or ICG was observed clinically or angiographically. Electron microscopy of the Tb-stained ERM specimens showed fragments of ILM in all specimens. CONCLUSIONS: Tb and ICG are useful intraoperatively to improve the visualisation and facilitate complete removal of ERM and ILM in macular ERM surgery.

Aged↗