Marcus C C Lim

Singapore Health Services, Tumasik, Singapore

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Publications (17)46.1 Total impact

  • Marcus C C Lim, Wing-Kwong Chan
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    ABSTRACT: To report a case of Salzmann nodular degeneration after laser in situ keratomileusis (LASIK). Case report. A 36-year-old woman with no significant medical history underwent routine myopic LASIK in both eyes and 3 months later developed Salzmann nodular degeneration at the inferotemporal and inferonasal flap edges of the left eye only. The visually inconsequential nodules, which did not respond to topical steroids, slowly increased in size and remained 4 years post-LASIK. Salzmann nodular degeneration is a rare complication of LASIK.
    Cornea 05/2009; 28(5):577-8. · 1.75 Impact Factor
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    ABSTRACT: To assess the ability of high-definition optical coherence tomography (HD-OCT) to image the anterior chamber angle. Forty-five consecutive subjects with phakic eyes underwent gonioscopy and anterior chamber angle imaging with HD-OCT adapted with a 60-diopter aspheric lens mounted over the imaging aperture. The patients' fixation was directed to the side using an external fixation light, and scans were taken of the temporal and nasal quadrants. The visibility of angle structures was assessed and the diagnosis of angle closure using HD-OCT was compared with that of gonioscopy. The majority of subjects were Chinese (91.1%) and female (62.2%). Cross-sectional HD-OCT allowed in vivo visualization of the scleral spur in 71 of 90 quadrants (78.9%) and the termination of the Descemet membrane (Schwalbe line) in 84 of 90 quadrants (93.3%). It was possible to image the trabecular meshwork in 56 quadrants (62.2%). Angle closure was observed in 17 eyes with gonioscopy and 12 eyes with HD-OCT (P = .12, McNemar test). The 2 modalities showed good agreement for angle closure diagnosis by quadrant (kappa = 0.65). The adapted HD-OCT provided magnified views of the anterior chamber angle and allowed visualization of the Schwalbe line and trabecular meshwork in most eyes.
    Archives of ophthalmology 04/2009; 127(3):256-60. · 3.86 Impact Factor
  • Marcus C C Lim, Han T Aung, Tin Aung, Audrey L G Looi
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    ABSTRACT: The human nasolabial fold angle (NFA) has been measured using MRI and photogrammetry and has been shown to decrease with age. The authors aimed to evaluate a novel method using optical coherence tomography to measure the NFA. In this cross-sectional observational series, the authors used anterior segment optical coherence tomography (ASOCT) to image the NFA of both cheeks of 126 subjects aged 21 to 79 years. A dental vinylpolysiloxane custom-designed mould was used as a chin rest. The mean of 3 scans on each side was calculated and analysis of variance, multiple comparisons, and multiple linear regression were carried out using SPSS 11.0. Sixty-one subject (48.4%) were men and 65 (51.6%) were women. Mean age was 50.6 +/- 16.8 years (range, 21-79 years). The ASOCT successfully imaged the NFA in all subjects. Mean right and left NFA were 144.4 degrees +/- 17.1 degrees and 145.4 degrees +/- 17.7 degrees. The NFA were dissimilar between the 6 age categories by decade (p < 0.001). Age was the significant predictor of NFA, accounting for 55% of NFA variation. Every year accounted for a decrease of 0.78 degrees (p < 0.001) and 0.80 degrees (p < 0.001) for the right and left cheeks, respectively. Male sex resulted in an increase in NFA of 5.4 degrees (p = 0.007) and 4.0 degrees (p = 0.06) in the right and left cheeks, respectively. The NFA decreases with age and increases with male sex and can be measured with ASOCT accurately and easily.
    Ophthalmic plastic and reconstructive surgery 01/2009; 25(5):387-9. · 0.69 Impact Factor
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    ABSTRACT: The aim of the study was to describe the prevalence and risk factors for diabetic retinopathy in a multi-ethnic diabetic patient cohort referred for retinal evaluation from a nationwide diabetic retinopathy screening programme in Singapore. Seven hundred and forty-two patients, aged 21 to 95, referred for suspected diabetic retinopathy on annual one-field non-mydriatic 45 degree retinal photographs (Topcon TRC-NW6, Topcon Corporation, Tokyo, Japan) from primary care to the Singapore National Eye Centre diabetic retinopathy clinic were included. The photographs had been interpreted by 24 trained family physicians accredited every 2 years with a training programme. Patients underwent a standardised interview and examination. Fundi were examined with indirect ophthalmoscopy by 2 examiners. Presence and severity of diabetic retinopathy was graded into none, mild, moderate, severe, very severe non-proliferative diabetic retinopathy and proliferative diabetic retinopathy. Macular oedema and clinically significant macular oedema were also graded. Ninety-nine per cent of patients were type 2 diabetics. The prevalence of diabetic retinopathy was 38.1%, visionthreatening retinopathy was 11.8% and macular oedema was 6.9%. There were no racial differences. Significant predictors of any retinopathy were longer duration of diabetes, lower body mass index, being on treatment for hypertension, hypercholesterolaemia and use of diabetic medication. Predictors for vision-threatening retinopathy were younger age, longer duration of diabetes and lower body mass index. The use of one-field non-mydriatic 45 degree photography as a screening tool for diabetic retinopathy resulted in a cohort of which 38.1% had diabetic retinopathy. Risk factors for diabetic retinopathy of this cohort are also presented.
    Annals of the Academy of Medicine, Singapore 10/2008; 37(9):753-9. · 1.36 Impact Factor
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    ABSTRACT: To estimate the direct costs of myopia in Singapore children. A cross-sectional study of 377 Singaporean school children aged 12-17 years from one school in Singapore Cohort study of the Risk factors for Myopia (SCORM) was conducted. A combination of parent and self-administered questionnaires asked about the cost of each optometrist visit, spectacles, and contact lenses, transport costs, father's educational level, and total family income. A total of 377 subjects participated and cost data were available from 301 subjects. The mean annual direct cost of myopia was S$221.7+/-313.7 (CI, S$186.5-258.1) or US$147.8+/-209.1 (CI, US$124.3-172.1) and median annual direct cost of myopia was S$125.0 or US$83.3. The mean cost per pair of spectacles was S$123.2+/-61.2 (CI, S$116.6-129.8) or US$82.1+/-40.8 (CI, US$77.8-86.5). Sixty subjects (15.9%) wore contact lenses. The mean annual cost of contact lenses was S$567.1+/-565.7 (CI, S$422.2-712.0) or US$378.1+/-377.1 (CI, US$281.4-474.6). Subjects of families with higher total family income and those with fathers with secondary or higher education had higher annual direct expenditure (P=0.03 and P=0.001 respectively). Subjects from families with higher household incomes had higher frequency of change of spectacles (P=0.02) and shorter time since the last change of spectacles (P=0.03). The mean annual direct cost of myopia for Singapore school children was S$221.68 (US$148) and the median, S$125.00 (US$83.33) per subject. Myopia is associated with significant financial burden in Singapore.
    Eye (London, England) 09/2008; 23(5):1086-9. · 1.97 Impact Factor
  • Marcus C C Lim, Tat-Keong Chan
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    ABSTRACT: To report a case of central serous chorioretinopathy after unilateral LASIK for hyperopia. A 50-year-old Chinese man underwent unilateral hyperopic LASIK in the right eye. One week postoperatively, he complained of poor vision. The working diagnosis 5 weeks postoperatively was hyperopic refractive surprise. Visual quality worsened over 5 months at which time a dilated fundus examination revealed central serous chorioretinopathy. Focal argon laser was performed, and visual acuity subsequently improved. Dilated fundus examination is helpful in revealing subtle retinal pathology that may be the cause of unexplained poor visual acuity following refractive surgery.
    Journal of refractive surgery (Thorofare, N.J.: 1995) 07/2008; 24(6):651-2. · 2.47 Impact Factor
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    ABSTRACT: Polypoidal choroidal vasculopathy (PCV) is a major cause of serosanguinous maculopathy in Chinese patients with age-related macular degeneration (AMD). Variants in the CFH and HTRA1/LOC387715 genes are strongly associated with AMD in Caucasians and Chinese. Variants in the C2 and BF genes have been found to confer a significantly reduced risk of AMD. This study was undertaken to determine whether these associations occur in Chinese patients with PCV. Patients of Chinese ethnicity with clinically and angiographically diagnosed PCV and normal control subjects were recruited from the Singapore National Eye Centre. Five single-nucleotide polymorphisms (SNPs) in the CFH gene, two each within the C2 and BF genes and two variants located in the LOC387715 and HTRA1 genes, were screened in all patients and control subjects. Seventy-two patients with PCV and 93 normal control subjects were studied. A significant association was noted with CFH variants rs3753394 and rs800292 among the PCV cases (P = 0.0015 and P = 0.0045, respectively). Individuals homozygous for the TT genotype of rs3753394 had a significantly higher risk (P = 0.0076) of PCV (OR = 4.29; 95% CI: 1.47-12.50) than those carrying a single copy of the T allele (P = 0.3210; OR = 1.69; 95% CI: 0.60-4.78), after adjustment for such risk factors as age and sex. The genotype frequencies of rs11200638 and rs10490924 in HTRA1 and LOC387715, respectively, were also found to be significantly different between patients with PCV and normal control subjects (P = 0.00032 and P = 0.003, respectively). The AA genotype of rs11200638 and TT genotype of rs10490924 conferred a 4.9-fold (95% CI: 1.85-12.95) and 4.89-fold (95% CI: 1.85-12.90) increased risk of PCV, respectively, after adjustment for age and sex. The Y402H variant of CFH (rs1061170) and the BF and C2 variants were not significantly different in patients and normal control subjects. The SNPs rs3753394 and rs800292 of CFH and rs11200638 of HTRA1 are significantly associated with the risk of PCV in Chinese patients.
    Investigative Ophthalmology &amp Visual Science 07/2008; 49(6):2613-9. · 3.44 Impact Factor
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    ABSTRACT: A recent study identified the single nucleotide polymorphism (SNP) rs2664538 within the MMP-9 gene with risk for acute primary angle closure glaucoma (PACG). The aim of this study was to confirm this association in Singaporean Chinese subjects with both acute and chronic PACG. This was an observational cross-sectional study. Genomic DNA was extracted from leukocytes of peripheral blood and genotypes were determined by polymerase chain reaction and direct sequencing. The association of the SNP with PACG was evaluated using chi tests. A total of 217 subjects with PACG (consisting of 85 acute and 132 chronic PACG), and 83 normal control Chinese subjects were studied. There was no significant difference in the rs2664538 SNP allele frequencies for acute or chronic PACG subjects compared with controls. This study did not find an association between the rs2664538 polymorphism within the MMP-9 gene and PACG in this sample of Chinese subjects.
    Journal of Glaucoma 05/2008; 17(4):257-8. · 1.87 Impact Factor
  • Ophthalmic Plastic and Reconstructive Surgery 01/2008; 24(3):245-6. · 0.67 Impact Factor
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    ABSTRACT: The genetic basis of primary angle closure glaucoma (PACG) has yet to be elucidated. Ocular characteristics related to PACG such as short hyperopic eyes with shallow anterior chambers suggest the involvement of genes that regulate ocular size. CHX10, a retinal homeobox gene associated with microphthalmia, and MFRP, the membrane-type frizzled-related protein gene underlying recessive nanophthalmos, represent good candidate genes for PACG due to the association with small eyes. To investigate the possible involvement of CHX10 and MFRP in PACG, we sequenced both genes in PACG patients with small ocular dimensions. One hundred and eight Chinese patients with axial lengths measuring 22.50 mm or less were selected for analysis. Ninety-three age- and ethnically-matched control subjects were also screened. Genomic DNA was extracted from leukocytes of peripheral blood samples, and the exons of CHX10 and MFRP were amplified by polymerase chain reaction (PCR) and subjected to bidirectional sequencing and analysis. All study patients were Chinese with a mean age of 66.2+/-9.1 years (range 46-86). There were 77 females (71.3%). Forty-nine out of the one hundred and eight subjects had previous symptomatic PACG, and 59 had asymptomatic PACG. The mean axial length was 21.90+/-0.50 mm (range 19.98-22.50 mm). We identified a possible disease-causing variant in CHX10 (c.728G>A) resulting in Gly243Asp substitution in one patient. This variant was not found in 215 normal controls. Several CHX10 and MFRP polymorphisms were also identified. Our results do not support a significant role for CHX10 or MFRP mutations in PACG.
    Molecular vision 01/2008; 14:1313-8. · 1.99 Impact Factor
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    ABSTRACT: A recent study identified single nucleotide polymorphisms (SNPs) within the IL-1 gene cluster at chromosomal locus 2q13 that were associated with reduced risk for primary open-angle glaucoma (POAG) in whites. The purpose of this study was to investigate the association between IL-1 SNPs and glaucoma in Chinese patients with either POAG or primary-angle closure glaucoma (PACG). Patients with POAG with a mean IOP without treatment that was consistently <21 mm Hg on diurnal testing were classified as having normal-tension glaucoma (NTG) and those with higher IOP were classified as having high-tension glaucoma (HTG). Subjects with PACG had at least 180 degrees of angle closure on gonioscopy. Genotypes were determined by polymerase chain reaction and restriction digest enzymes at the following loci: IL1A (-889C/T), IL1B (+3953C/T), and IL1B (-511C/T). The association of individual SNPs with glaucoma was evaluated by using chi(2) testing. Haplotype analysis was performed with the PHASE program, with haplotype frequency estimated for combined cases and controls, assuming Hardy-Weinberg equilibrium (HWE) of haplotypes. Of the Chinese subjects studies, 194 had POAG (94 NTG and 100 HTG), 125 had PACG, and 79 were normal control subjects. There was no significant difference in IL-1 SNP or allele frequencies for in subjects with POAG or PACG compared with control subjects, or between NTG and HTG. None of the common haplotypes showed any significant difference between the HTG, NTG, PACG, and normal control subjects. This study did not find an association between IL-1 gene cluster polymorphisms and glaucoma in this sample of Chinese subjects.
    Investigative Ophthalmology &amp Visual Science 05/2007; 48(5):2123-6. · 3.44 Impact Factor
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    ABSTRACT: To compare lens thickness (LT), lens position (LP), relative lens position (RLP), and degree and type of lens opacity between affected and fellow eyes of subjects with acute primary angle closure (APAC) to identify any differences in lens characteristics that may be contributory to the acute episode. In addition, axial length (AL) and anterior chamber depth (ACD) measurements were evaluated. Seventy-three study subjects with unilateral APAC were treated with sequential laser iridotomy (LI) in both eyes. Two weeks after LI, ACD, LT, and AL measurements were made in both eyes using ultrasound pachymetry. LP was defined as ACD+1/2LT and RLP as LP/AL. The Lens Opacity Classification III (LOCS III) System was used for grading lens opacity. The subjects were 90% Chinese and 63% female. Mean age was 61.0+/-10.9 years. Significant differences between the affected and fellow eyes were found in the ACD (2.11+/-0.35 vs 2.18+/-0.23; P=0.02) and LP (4.61+/-0.47 vs 4.75+/-0.29; P=0.02). Cortical opacity was greater in fellow eyes (0.32+/-0.72 vs 0.53+/-0.95; P=0.02). There was no difference in LT, RLP, or degree of lens opacity in the nuclear and posterior subcapsular regions. Compared with fellow eyes, APAC-affected eyes have shallower ACD, more anterior LP, and less cortical opacity. These differences may be contributory to APAC.
    Journal of Glaucoma 07/2006; 15(3):260-3. · 1.87 Impact Factor
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    ABSTRACT: To determine the relationship between peripapillary retinal nerve fiber layer (RNFL) thickness and myopia using optical coherence tomography (OCT). Prospective observational case series. One hundred thirty-two young males with myopia (spherical equivalent [SE], -0.50 to -14.25 diopters) underwent ophthalmic examination of one randomly selected eye. Optical coherence tomography (OCT-1, version 4.1) was performed by a single operator using circular scans concentric with the optic disc with scan diameters of 3.40 mm, 4.50 mm, and 1.75 x vertical disc diameter (VDD). For each scan diameter, mean peripapillary RNFL thickness was calculated. Statistical analysis comprised repeated-measurements analysis and Pearson correlation. Mean peripapillary RNFL thickness did not correlate with SE for the 3.40-mm (r = -0.11, P = 0.22), 4.50-mm (r = -0.103, P = 0.24), or 1.75xVDD (r = -0.08, P = 0.36) OCT scan diameters. Neither did mean peripapillary RNFL thickness correlate with axial length for the 3.40-mm (r = -0.04, P = 0.62), 4.50-mm (r = 0.03, P=0.75), or 1.75xVDD (r = -0.02, P = 0.78) scan diameters. Mean peripapillary RNFL thicknesses for the 3.40-mm, 4.50-mm, and 1.75xVDD scans were 101.1+/-8.2 microm (95% confidence interval [CI], 99.4-102.8), 78.9+/-8.2 microm (95% CI, 77.5-80.3), and 97.5+/-10.9 microm (95% CI, 95.6-99.4), respectively. Mean peripapillary RNFL thickness did not vary with myopic SE or axial length for any OCT scan diameter investigated. Retinal NFL thickness measurements may be a useful parameter to assess and monitor glaucoma damage in myopic subjects.
    Ophthalmology 06/2006; 113(5):773-7. · 5.56 Impact Factor
  • Marcus C C Lim, Aliza H E Jap, Edmund Y M Wong
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    ABSTRACT: A case of late spontaneous dislocation of the lens capsular bag (CB) with foldable acrylic intraocular lens (IOL) and endocapsular tension ring (CTR) and its surgical management is reported in a 52-year-old man. The dislocation occurred 2 years 3 months after phacoemulsification cataract surgery in which a CTR was used for zonular instability. A 3-port pars plana vitrectomy was performed. Because it was not possible to grasp the IOL-CTR-CB complex, perfluorocarbon liquid was used to attempt to float it up. This was unsuccessful, so a scleral indenter was used to apply external pressure on the sclera to tilt the IOL-CTR-CB complex into a position where it could be grasped with a forceps and removed through a corneal section. A scleral-fixated IOL was placed, and the patient achieved a best corrected visual acuity of 6/9. The procedure was safe and effective without intraocular complications.
    Journal of Cataract and Refractive Surgery 04/2006; 32(3):533-5. · 2.53 Impact Factor
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    ABSTRACT: To evaluate the use of Surodex (Oculex Pharmaceuticals, Sunnyvale, California) a drug delivery system incorporating 60 micrograms of dexamethasone in a pellet, in phacotrabeculectomy surgery. Nonrandomized, prospective, interventional case series. Phacotrabeculectomy was performed on 37 Asian subjects with primary open-angle glaucoma (POAG) using a standardized technique. All subjects received a Surodex pellet underneath the scleral flap. Results were compared with those of 31 POAG subjects who had undergone phacotrabeculectomy augmented with 50 mg/ml of intraoperative 5-fluorouracil (5-FU) during the same period. Mean follow-up in months was 19.7 +/- 7.9 and 22.1 +/- 6.2 for the Surodex and 5-FU groups, respectively (P = .29). There was a 20.1% decrease in intraocular pressure in the Surodex group compared with 28.5% decrease in the 5-FU group (P = .6). Postoperative complications occurred in three cases (8.1%) and six cases (19.3%), respectively (P = .04). Combined phacotrabeculectomy surgery augmented by intra-scleral placement of Surodex results in good control of IOP and a low incidence of complications.
    American Journal of Ophthalmology 06/2005; 139(5):927-8. · 3.63 Impact Factor
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    ABSTRACT: To investigate the variation in macular retinal thickness in otherwise normal young Asian myopic subjects by using optical coherence tomography (OCT). One hundred thirty ophthalmically normal men 19 to 24 years of age with myopia (spherical equivalent, -0.25 to -14.25 D) underwent examination of one randomly selected eye. Visual acuity, refraction, slit lamp examination, applanation tonometry, gonioscopy, A-scan ultrasound, fundus examination, visual field testing, and optic disc photography were performed. Exclusion criteria were visual acuity worse than 20/30, previous intraocular surgery, intraocular pressure >21 mm Hg, or other ocular diseases. Three horizontal transfixation and three vertical transfixation OCT scans (ver.4.1; Carl Zeiss Meditec, Dublin, CA) of 6 mm each were conducted on each eye by a single operator. Neurosensory retinal thicknesses at 100 points along each scan were measured, and the overall average, maximum, and minimum retinal thicknesses were analyzed by simple linear regression and analysis of variance. The average macular retinal thickness (overall) was 230.9 +/- 10.5 microm and was not significantly related to the degree of myopia. The mean maximum retinal thickness (at the parafovea) was 278.4 +/- 13.0 microm, and correlated negatively with axial length (P = 0.03). The mean minimum retinal thickness (at the foveola) was 141.1 +/- 19.1 microm, and this was positively correlated with axial length (P = 0.015) and spherical equivalent (P = 0.0002). The retina was thicker at the superior and nasal parafovea compared to the inferior or temporal parafovea. Average retinal thickness of the macula does not vary with myopia. However, the parafovea was thinner and the fovea thicker with myopia.
    Investigative Ophthalmology &amp Visual Science 04/2005; 46(3):974-8. · 3.44 Impact Factor
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    ABSTRACT: To investigate the relationship between drainage angle configuration with untreated intraocular pressure (IOP) and optic disc cupping in subjects with chronic angle-closure glaucoma (CACG). Prospective, observational study. Two hundred seventy-five Asian subjects with CACG who participated in a randomized controlled trial that investigated the IOP-reducing effect of latanoprost and timolol. Chronic angle-closure glaucoma was defined as the presence of glaucomatous optic neuropathy (with or without a visual field defect), an anterior chamber angle in which the pigmented trabecular meshwork was not visible for at least 180 degrees on gonioscopy, and evidence of peripheral anterior synechiae (PAS) in association with elevated IOP of 21 mmHg or more. Static and dynamic gonioscopy were performed, the angles were graded in each quadrant according to the Shaffer scheme, and the number of clock hours of PAS was recorded. The untreated IOP and vertical cup-to-disc ratio were correlated with mean angle width and extent of PAS. Mean angle width, clock hours of PAS, IOP, and vertical cup-to-disc ratio. Most subjects were female (75%), and the mean age was 62.9+/-9.4 years. The mean angle width was 0.77+/-0.53 and the mean number of clock hours of PAS was 4.77+/-3.2 hours. Untreated IOP correlated with angle width (r = -0.23; P<0.001) and clock hours of PAS (r = 0.22; P<0.001). Vertical cup-to-disc ratio also correlated with angle width (r = -0.17; P = 0.004) and PAS (r = 0.28; P<0.001). Performing a multiple linear regression using baseline IOP as the outcome variable with age, gender, clock hours of PAS, and angle width as predictors, there was a 0.39-mmHg (95% confidence interval, 0.15-0.63) increase in baseline untreated IOP for each unit increase in clock hours of PAS (P = 0.002). In subjects with CACG, the extent of PAS and a narrower width of the drainage angle were associated with higher untreated IOP and a larger vertical cup-to-disc ratio.
    Ophthalmology 01/2005; 112(1):28-32. · 5.56 Impact Factor

Publication Stats

234 Citations
4 Downloads
1k Views
46.10 Total Impact Points

Institutions

  • 2009
    • Singapore Health Services
      Tumasik, Singapore
    • Tan Tock Seng Hospital
      Tumasik, Singapore
  • 2005–2009
    • Singapore National Eye Centre
      Tumasik, Singapore