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Biomedical subjects

Dorothy S P Fan

Publications and source records attributed to Dorothy S P Fan.

At least 19 recordsLinked to original sources
PubMed2006

Changes in refraction and ocular dimensions after cataract surgery and primary intraocular lens implantation in infants.

PURPOSE: To study refraction and axial length changes after cataract extraction and primary intraocular lens (IOL) implantation in children younger than 1 year of age. SETTING: Two regional hospitals. METHODS: After determining the IOL power for emmetropia, 80% of the value was used to choose the IOL for implantation to counter anticipated myopic shift with age. The main outcome measures were changes in refraction and axial length 3 years after surgery. RESULTS: Thirty-four eyes of 20 children (mean age 6.7 months +/- 3.9 [SD]) were studied. Refraction in the immediate postoperative period was +4.53 +/- 1.45 diopters (D). Three years after surgery, the mean refraction was -2.49 +/- 3.08 D (P<.001). Twenty-two eyes (64.7%) had surgery during the first 6 months of life (group 1) and had a shorter axial length at surgery (mean 18.92 +/- 1.32 mm) compared with 12 eyes (35.3%) that received surgery between 7 and 12 months (group 2, mean 20.29 +/- 1.00 mm) (P = .007). However, the final axial length was greater in group 1 (mean 22.67 +/- 1.04 mm) than in group 2 (mean 21.23 +/- 0.26 mm) (P = .019). CONCLUSIONS: Primary IOL implantation is an option for children having cataract surgery in the first year of life. Significant myopic shifts occurred, and this seemed to be more pronounced in younger children. It appears that rethinking current strategies for IOL power calculation may be required to achieve more optimal refractive outcomes.

Cataract↗
PubMed2006

The use of peribulbar anaesthesia in paediatric cataract surgery (age 7-15 years) in a mobile eye camp in China.

AIM: To evaluate the feasibility and acceptability of the use of peribulbar anaesthesia (PA) in paediatric cataract surgery in rural areas in China, where there are limitations in expertise and equipment for general anaesthesia (GA). METHODS: We prospectively evaluated the feasibility and acceptability of carrying out paediatric cataract surgery under PA in children aged 7-15 years. Informed consent was obtained from the subjects and their parents. Children were assessed for their suitability for PA. Peribulbar anaesthesia was given as a peribulbar block using a 2% lidocaine, 0.5% bupivacaine-hyaluronidase mixture administered before lens aspiration with intraocular lens implantation. The acceptability of the PA was evaluated by questionnaire. RESULTS: A total of 19 patients were recruited. Their mean age was 12 +/- 2 years (range 7-15 years). None required conversion to GA. All subjects regarded PA as either totally acceptable (63.2%) or acceptable (36.8%). The mean pain scores (from 0 to 100) during the injection and surgery were 28 +/- 26 and 6 +/- 8, respectively. Seventeen patients (89.5%) said they would prefer PA if choices in anaesthesia were offered again. CONCLUSIONS: Peribulbar anaesthesia can be considered as a viable option in selected children undergoing cataract surgery when facilities for safe and optimal general anaesthesia are unavailable.

Adolescent↗
PubMed2006

Updates on the surgical management of paediatric cataract with primary intraocular lens implantation.

With the advent of modern surgical techniques, paediatric cataract has become much more manageable. Intraocular lens (IOL) implantation is the standard of care for patients over the age of 2 years. The use of IOL in young infants is still controversial. In addition, there are still unresolved issues, such as the minimum age at which IOL can be safely implanted, IOL power selection and IOL power calculation. The current trends in the management of the above challenges are discussed. Although numerous reports on the prevention and management of posterior capsule opacification have been published, there are ongoing intensive debates and research. Long-term postoperative complications like glaucoma and rhegmatogenous retinal detachment are problems that cannot be overemphasised and these issues are also reviewed.

Cataract↗
PubMed2005

Failure of systemic antibiotic in preventing sequential endogenous endophthalmitis of a bronchiectasis patient.

PURPOSE: To report a rare presentation of bilateral, sequential Pseudomonas aeruginosa endogenous endophthalmitis in a woman with bronchiectasis. DESIGN: Interventional case report. METHODS: A 69-year-old woman with bronchiectasis developed right and then left endogenous endophthalmitis with the microbial of P. aeruginosa, even though a course of 3-week intravenous ceftazidime antibiotic was prescribed. RESULTS: The presentation of endogenous endophthalmitis in the right eye was late, and final visual acuity was hand movements. The condition was recognized much earlier in the left eye, and the infection was treated early on with vitrectomy and intravitreal antibiotics. Visual acuity at 1 year was stable at 20/40. CONCLUSION: Systemic antibiotic failed to eradicate the primary source of Pseudomonas infection in the bronchiectasis patient. Unusual, painful red eye may be the presenting feature of endogenous endophthalmitis. Early vitrectomy may be considered in endogenous endophthalmitis caused by virulent pathogens such P. aeruginosa.

Aged↗
PubMed2005

Macular pigment optical density in a Chinese sample.

PURPOSE: Extensive efforts have been devoted to determining the macular pigment optical density (MPOD) in Caucasian subjects. Unfortunately, no such data in ethnic groups with naturally dark irises are currently available. In this study, we report the values in a sample of Chinese subjects. METHODS: The MPOD was measured psychophysically using a densitometer at 0.25 degrees , 0.50 degrees , 1.00 degrees , and 2.00 degrees eccentricity from the foveal center in 92 Chinese subjects. RESULTS: The spatial profile for the averaged MPOD was approximately exponential in form and showed a decline with age (r = -0.23). Subjects aged below 60 years had significantly higher averaged MPOD than those aged 60 years or above. Significant gender differences, in favor of males, were also found in the middle-age groups. CONCLUSIONS: Our study reports for the first time the MPOD in a Chinese population. Baseline information on MPOD would aid future research in preventive measures against age-related macular degeneration.

Adolescent↗
PubMed2005

Prevalence and characteristics of peripheral retinal degeneration in Chinese adults with high myopia: a cross-sectional prevalence survey.

PURPOSE: The purpose of this study was to study the prevalence of peripheral retinal findings in adult Chinese patients with high myopia (refraction < or = -6.00 D) and to investigate the correlation between the retinal lesions and the severity of myopia or axial length. METHODS: A cross-sectional prevalence survey screening was conducted in high ethnic Chinese myopes with refractions equal to or less than -6.00 D. The examinations included cycloplegic refraction, A and B scan ultrasonography, and retinal examinations by indirect ophthalmoscopy with scleral indentation and Goldmann three-mirror contact lens examination. RESULTS: Two hundred thirteen eyes in 213 patients with a mean refraction of -10.10 +/- 4.23 D (range = -6.00 to -27.00 D) were examined. The mean axial length was 26.69 +/- 1.68 mm (range = 25.18-33.62 mm) and the mean age was 33.5 +/- 10.6 years (range = 18-73 years). The most common peripheral retinal finding was pigmentary degeneration (51.2%), followed by lattice degeneration in 12.2% and retinal holes in 7.5% of eyes. A positive correlation was noted between axial length and the lesions of pigmentary degeneration and pavingstone degeneration. The prevalence of retinal holes was 6.4% and 30.0% in eyes with axial length of < 30 mm and > or = 30 mm, respectively (chi-squared test, p = 0.006). CONCLUSION: A high prevalence of peripheral retinal degenerations was found in adult Chinese high myopes. The presence of retinal holes was positively correlated with very high myopia of an axial length of > or = 30 mm.

Adult↗
PubMed2005

Intraocular pressure measurement in patients with previous LASIK surgery using pressure phosphene tonometer.

PURPOSE: To compare intraocular pressure (IOP) assessment in post-LASIK patients using non-contact tonometry, pressure phosphene tonometry and applanation tonometry. METHODS: Sixty-two consecutive LASIK patients were analysed preoperatively and postoperatively with non-contact, pressure phosphene and applanation tonometry. Comparisons among these values were assessed with paired sample Student t-test, Pearson's correlation test and Bland-Altman plotting. RESULTS: There was no significant difference for preoperative IOP measurement between non-contact, pressure phosphene and applanation tonometry. The mean +/-SD difference between the preoperative non-contact tonometry and postoperative pressure phosphene tonometry IOP measurements was 0.80 +/- 2.77 mmHg (P < 0.01). Postoperative applanation tonometry significantly underestimated IOP measurement by 5.45 +/- 2.96 mmHg (P < 0.001) and postoperative non-contact tonometry significantly underestimated IOP measurement by 9.96 +/- 2.25 mmHg (P < 0.001). CONCLUSION: Pressure phosphene tonometry may provide an alternative method for the assessment of IOP in post-LASIK patients.

Adult↗
PubMed2005

Ocular hypertensive and anti-inflammatory responses to different dosages of topical dexamethasone in children: a randomized trial.

BACKGROUND: The purpose of the present study was to investigate the ocular hypertensive and anti-inflammatory responses to two different dosage schedules of 0.1% topical dexamethasone in a population of Chinese children undergoing strabismus surgery. METHODS: Children undergoing bilateral strabismus surgeries were randomly assigned to receive topical 0.1% dexamethasone eye drops four times daily (group A) or twice daily (group B) for 4 weeks. Intraocular pressure (IOP) and anti-inflammatory responses were monitored for 8 weeks. RESULTS: A total of 137 children with mean age 6.5 years (SD, 1.9 years; range, 3-10 years) participated in the study. The IOP increased significantly after 4 weeks in both groups compared to the preoperative values (P < 0.001). Peak IOP ranged from 14.0 to 50.3 mmHg in group A and 11.0-41.3 mmHg in group B. Cases in group A (mean, 13.8 mmHg; SD, 8.4 mmHg) had a greater net increase in IOP than cases in group B (mean, 10.2 mmHg; SD, 6.2 mmHg; P = 0.004). Younger-aged children had higher peak IOP (r = -0.244, P = 0.048), and attained the peak IOP earlier (r = 0.252, P = 0.041) in group A. There was no significant difference in ocular inflammatory response between the two groups. CONCLUSION: Ocular hypertensive effect to topical 0.1% dexamethasone is dose and age dependent in children. Twice-daily 0.1% topical dexamethasone eye drops control inflammation after strabismus surgery as effectively as four-times-daily dosage, but induces less increase in IOP, and may be a better treatment schedule.

Age Factors↗
PubMed2005

25-gauge transconjunctival sutureless vitrectomy system in the surgical management of children with posterior capsular opacification.

PURPOSE: To evaluate the safety and efficacy of the 25-gauge transconjunctival sutureless vitrectomy (TSV) system in the surgical management of posterior capsular opacification (PCO) in pseudophakic children. METHODS: Pars plana membranectomy was performed for PCO in 10 pseudophakic eyes of six children (mean age 35.1 +/- 37.8 months; range 6-93 months) using the TSV system. Surgical technique, intraoperative problems and postoperative complications including wound leakage, hypotony and the need for suturing were recorded. RESULTS: Wound leakage and other intraoperative problems were not noted in any of the eyes. All eyes showed improvement of visual acuity from a mean of 6/67 before to 6/29 after surgery (P = 0.001). Mean postoperative intraocular pressure (IOP) was 7.8 +/- 3.1 mmHg (range: 3-10 mmHg). Four eyes (40%) had hypotony on the first postoperative day (IOP: 3-5 mmHg), which was transient in three eyes. One eye in a patient with uveitis had persistent hypotony, but hypotony was also present preoperatively, and the postoperative IOP returned to preoperative levels. This eye also developed recurrent PCO and a second capsulotomy was performed using the 25-gauge TSV system. CONCLUSIONS: Posterior capsulotomy using the 25-gauge TSV system appears to be a safe and effective approach in the management of PCO in pseudophakic children. Advantages include easier manipulation with the smaller instruments in these small eyes, and it can be considered in appropriate cases.

Cataract↗
PubMed2005

The effect of parental history of myopia on eye size of pre-school children: a pilot study.

PURPOSE: To evaluate parental history of myopia as a predictor of refractive error and eye size in Chinese pre-school children. METHODS: A total of 514 pre-school children (aged 2.3--6.4 years) were examined. Parental history of myopia, amount of near work performed, refractive status and ocular biometry were recorded. RESULTS: There was no significant difference in spherical equivalent refraction (SER) among children with no myopic parents (mean+0.94+/-0.05 D), one myopic parent (mean+0.77+- 0.07 D) and two myopic parents (mean+0.79+/- 0.12 D) (p=0.102) after controlling for age and amount of near work. Further, children with more myopic parents did not have longer eyeballs (p=0.335). CONCLUSIONS: In this study in Chinese pre-school children, parental history of myopia was not found to be associated with a myopic refractive error or increased eyeball length. Further studies with larger sample sizes would help to confirm these results.

Asian People↗
PubMed2005

Clinical implications of promoter hypermethylation in RASSF1A and MGMT in retinoblastoma.

We investigated the epigenetic silencing and genetic changes of the RAS-associated domain family 1A (RASSF1A) gene and the O6-methylguanine-DNA methyltransferase (MGMT) gene in retinoblastoma. We extracted DNA from microdissected tumor and normal retina tissues of the same patient in 68 retinoblastoma cases. Promoter methylation in RASSF1A and MGMT was analyzed by methylation-specific PCR, RASSF1A sequence alterations in all coding exons by direct DNA sequencing, and RASSF1A expression by RT-PCR. Cell cycle staging was analyzed by flow cytometry. We detected RASSF1A promoter hypermethylation in 82% of retinoblastoma, in tumor tissues only but not in adjacent normal retinal tissue cells. There was no expression of RASSF1A transcripts in all hypermethylated samples, but RASSF1A transcripts were restored after 5-aza-2'-deoxycytidine treatment with no changes in cell cycle or apoptosis. No mutation in the RASSF1A sequence was found. MGMT hypermethylation was present in 15% of the retinoblastoma samples, and the absence of MGMT hypermethylation was associated (P = .002) with retinoblastoma at advanced Reese-Ellsworth tumor stage. Our results revealed a high RASSF1A hypermethylation frequency in retinoblastoma. The correlation of MGMT inactivation by promoter hypermethylation with lower-stage diseases indicated that MGMT hypermethylation provides useful prognostic information. Epigenetic mechanism plays an important role in the progression of retinoblastoma.

Cell Cycle↗
PubMed2004

Absence of myocilin and optineurin mutations in a large Philippine family with juvenile onset primary open angle glaucoma.

PURPOSE: To analyze the role of the two primary open angle glaucoma (POAG) genes, myocilin (MYOC) and optineurin (OPTN), in a large Philippine family segregating autosomal dominant juvenile onset open angle glaucoma (JOAG). METHODS: The coding sequences of the MYOC and OPTN genes were screened in 27 family members by polymerase chain reaction and direct sequencing. The specific MYOC promoter polymorphism (MYOC.mtl) was identified by restriction endonuclease assay. All of the ABI MD-10 microsatellite markers on chromosomes 1, 2, 3, 7, 8, and 10, which harbor the six known POAG loci, were analyzed for linkage with POAG. RESULTS: No mutation was identified in this large kindred. Instead, three polymorphisms (-80G->A, -1000G->C, R76K) in MYOC and four polymorphisms (T34T, M98K, R545Q, IVS7+24G->A) in OPTN were found. All markers flanking the six known POAG loci gave LOD scores not more than 1.1. Non-parametric linkage analysis for all these markers resulted in p values more than 0.05. CONCLUSIONS: Both mutation testing and linkage analysis provide strong evidence against MYOC and OPTN being the causative gene in this large family. It indicates that unidentified genes will underlie the occurrence of glaucoma in this family.

Adult↗
PubMed2004

Ocular screening in severe acute respiratory syndrome.

PURPOSE: To investigate the ocular manifestations of patients with severe acute respiratory syndrome (SARS) and to monitor the possible ocular complications arising from the treatment regimen with high-dose systemic corticosteroid drugs. DESIGN: Prospective, observational cohort case series. METHODS: Ninety eyes from 45 patients with the diagnosis of SARS during an epidemic outbreak in Hong Kong were analyzed. Relevant medical and ophthalmic histories were taken. Ophthalmic examinations, including best-corrected visual acuity, intraocular pressure, slit-lamp, and indirect ophthalmoscopy examination, were performed at baseline and at 2-month and 3-month follow-up. SETTING: Faculty practice in university hospital. RESULTS: Only two patients had mild elevated intraocular pressure at baseline and at subsequent follow-up. There was no loss of visual acuity, cataract progression, or increased cup-disk ratio. Fundus examinations were unremarkable in all patients. CONCLUSIONS: Our study did not demonstrate any ocular manifestations in patients with SARS. The treatment regimen of high-dose corticosteroid also did not show any significant ocular complications. Routine ocular screening of patients with SARS for diagnosis or for complications might not be indicated.

Adult↗
PubMed2004

Polymorphisms in the myocilin promoter unrelated to the risk and severity of primary open-angle glaucoma.

PURPOSE: To investigate the proximal 2.5 kb promoter in the myocilin (MYOC) gene for mutations in Chinese patients with primary open-angle glaucoma (POAG). PATIENTS AND METHODS: We screened for sequence alterations in the MYOC promoter in 88 unrelated Chinese patients with POAG and 94 unrelated individuals without glaucoma, aged 50 years or above, as control subjects. In addition, the specific MYOC.mt1 polymorphism was determined in a total of 212 POAG patients and 221 control subjects. The relationships between POAG phenotype and the identified polymorphisms were studied by univariate analysis, multivariable logistic regression analysis, and haplotype analysis. RESULTS: All polymorphisms identified in this study followed Hardy-Weinberg equilibrium (P > 0.12) both in POAG patients and controls. Both univariate and multivariable logistic regression analyses showed no polymorphism that was significantly associated with the risk of POAG, P > 0.08 and P > 0.044 respectively. Haplotype analysis further indicated no association of MYOC promoter polymorphisms with the susceptibility for POAG (P > 0.1). On the other hand, there was no difference of POAG phenotypes among different genotypes of MYOC.mt1 (P > 0.31). CONCLUSIONS: In this study on the Chinese population, polymorphisms in the MYOC promoter are not related to the risk of POAG. There is no association between the MYOC.mt1 promoter polymorphism with the severity of POAG.

Adolescent↗
PubMed2004

Comparative study on the safety and efficacy of different cycloplegic agents in children with darkly pigmented irides.

BACKGROUND: The ideal cycloplegic drug that is safe, effective and convenient in children is not yet available. This study aimed to evaluate the safety and efficacy of three cycloplegic regimens in hyperopic children with pigmented irides. The responses to cycloplegia in different age groups and presence of strabismus were also compared. METHODS: Tropicamide 0.5% and phenylephrine 0.5% (regimen I), tropicamide 1.0% and cyclopentolate 1.0% (regimen II), and atropine 1.0% (regimen III) were evaluated in 25 children using a crossover study design. Cycloplegic refractions were assessed. RESULTS: The mean age of the children was 5.7 +/- 2.0 years (range 2.5-10.8 years). Six (24.0%) of them had strabismus. The spherical equivalent (SE) refraction for regimens I, II and III were +5.11 +/- 2.04 D, +5.29 +/- 1.89 D and +5.71 +/- 1.90 D, respectively, and were significant different from the manifest SE (+3.95 +/- 2.17 D) (P < 0.001). There was no statistical difference between regimen I and II in children without strabismus (P = 0.258) or aged older than 5 years (P > 0.050). CONCLUSION: In older children, regimen I was as effective as regimen II and can be used to avoid cyclopentolate toxicity.

Atropine↗