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Biomedical subjects

S J Chew

Publications and source records attributed to S J Chew.

48 records · Page 3Linked to original sources
PubMed1991

A study of amblyopia in 18-19 year old males.

During a vision screening of 6,556 National Service pre-enlistees aged 18-19 years at the Medical Classification Centre of Central Manpower Base, 48 subjects were found to have visual acuity of 6/12 or less in one or both eyes in the absence of ocular pathology. The prevalence of amblyopia in this population is 0.73%. Amblyopia was due to anisometropia in 24 cases (50%), strabismus in 9 cases (18.7%), high astigmatism (meridional) in 7 cases (14.5%) and other causes or a combination of factors in 8 cases (16.7%). Strabismic amblyopia is most commonly associated with esotropia. There is a positive association between the severity of amblyopia and the degree of strabismus in strabismic amblyopes. Meridional amblyopia tends to be less severe than most other types of amblyopia. The amblyopes were detected late (average 7-10 years of age) and orthoptic treatment of a small minority of them upon diagnosis was unsuccessful.

Adolescent↗
PubMed1991

Validation of the General Health Questionnaire in female video display unit (VDU) operators in Singapore.

Fifty-seven Chinese female Video Display Unit operators employed in a multi-national company were asked to complete the 28-item General Health Questionnaire (GHQ-28). This is part of a study on stress and asthenopia in this group of workers. Validity of the GHQ-28 was determined by comparison with the Clinical Interview Schedule (CIS). The GHQ-28 was found to give optimum results with a cut-off score of 5/6. The CIS classified 28.07% as cases and this was comparable to the estimated prevalence of 28.03% derived from the GHQ.

Adult↗
PubMed1991

Paraneoplastic optic neuropathy in nasopharyngeal carcinoma--report of a case.

A 31-year-old Chinese man developed left optic neuritis with left sectorial field loss as a remote effect of nasopharyngeal carcinoma. The field defect showed interesting fluctuations in response to the dosage of systemic steroid therapy. Neuropathologic findings from an exploratory craniotomy did not show any gross tumour mass around the left optic nerve nor any histological evidence of tumour infiltration. This case illustrates that "optic neuritis" could be a paraneoplastic effect of nasopharyngeal carcinoma.

Adult↗
PubMed1990

Refractive errors in Singapore medical students.

The refraction of 128 third-year medical students aged 20-22 was studied using a Topcon autorefractometer. The population was predominantly Chinese and comprised 44% females and 56% males. The mean refractive error was -3.75 D for males and -4.76D for females. In all, 82% of the students were myopic, 72% were found to have astigmatism. This study confirms clinical impressions that Singapore students have one of the highest prevalence rates of myopia and astigmatism in the world.

Adult↗
PubMed1990

Ophthalmic screening for diabetics: the importance of physician-ophthalmologist collaboration in the prevention of blindness.

Diabetes mellitus as a disease is a dragon with many heads. To cope with it, each manifestation must be deftly handled by family physician and specialists in unison. Similarly, the spectre of diabetic retinopathy is best exorcised before it manifests - by effective prophylactic screening. This programme can only be successful through a co-ordinated effort of both physicians and ophthalmologists. In this paper, we present one such agenda which we have adopted, The result indicate that a fifth of diabetics have retinopathy, and that sight threatening disease affects 7% of those screened. More critically, it also establishes that a cost-effective method of screening can be achieved through a synergetic endeavour of primary care physician and specialist.

Adolescent↗
PubMed1990

Leber's hereditary optic atrophy: an atypical case with response to hydroxycobalamine therapy.

A 15-year old Chinese boy was diagnosed to have Leber's hereditary optic neuropathy (LHOA), having manifested with typical findings of bilateral severe visual loss and telangiectasia at the optic disc. However, no family history was elicited and an interval of more than 5 years separated visual loss in the two eyes. The latter is an extremely uncommon finding. Visual improvement was rapid and marked after instituting intramuscular hydroxycobalamine 5 mg weekly. Bilateral improvement of Snellen acuity to 6/9 was achieved within 6 months. This is also unusual in that visual prognosis is generally poor in LHOA, although spontaneous remissions have occasionally been recorded. In addition, the eye with a longer history of poor vision responded to therapy first.

Adolescent↗
PubMedDate not supplied

Confocal microscopy of corneal penetration by tarantula hairs.

In vivo identification of foreign bodies in the cornea may be impossible if the size and/or location precludes visualization by slit lamp biomicroscopy, which has an upper limit of magnification of 50x. These limitations became obvious when we attempted to identify the offending material in the inflamed eye of a patient who complained of foreign body sensation after contact with a pet tarantula. As a model of this clinical situation, we used a newly developed tandem scanning confocal microscope to observe and to photograph tarantula hairs as they penetrated the corneal stroma and endothelium and entered the anterior chamber in rabbit eyes. We found that, experimentally, the hairs penetrated the ocular tissues apparently without inciting inflammation or causing fibrosis. The instrument we used--a prototype with a Nipkow disk from Noran, Inc. (Middleton, Wis.) and a 25/0.8 na glycerin immersion lens (Plan-Neofluor, Zeiss)--provides magnifications of 100-500x, real-time viewing in vivo, optical sectioning, contrast control, high resolution, processing through image analysis systems, and video and hard copy output. We believe that confocal microscopy offers a new approach to the identification and localization of foreign bodies in the anterior segment, as well as to the visualization and diagnosis of ocular diseases, including bacterial, fungal, and other parasitic invasions, in the human eye.

Animals↗
PubMedDate not supplied

Near-work activity and myopia in rural and urban schoolchildren in China.

PURPOSE: To examine the prevalence of myopia in rural and urban schoolchildren in Xiamen, China, and to assess the impact of environmental factors on rates of myopia. METHODS: Second-grade children attending either a city (n=119) or rural (n=91) school in Xiamen, China, were examined using cycloplegic autorefraction and biometry. Detailed questions on socioeconomic status, near-work activity, reading and writing habits, and family histories of myopia were asked in a face-to-face interview using a standard questionnaire. RESULTS: The prevalence of myopia was 19.3% (95% confidence interval [CI], 12.3, 29) in the city and 6.6% (95% CI, 2.4, 14.3) in the countryside. The average hours per day children spent reading and writing outside of school was 2.2 hours in the city compared with 1.6 hours in the countryside (P<.0001). In both schools, the odds ratio for total reading and writing, adjusted for parental history of myopia, was 2.2 (95% CI, 1.1, 4). CONCLUSION: These data suggest the prevalence of myopia is higher in the city than in the countryside. One possible explanation for these different rates could be that schoolchildren in the city spend more time reading and writing outside of school compared with children in the countryside. Myopic children in both the city and the countryside spent more time reading and writing compared with nonmyopic children. This increased near-work activity may contribute to the prevalence of myopia.

Child↗
PubMedDate not supplied

Real-time confocal microscopy of keratocyte activity in wound healing after cryoablation in rabbit corneas.

A modified tandem scanning confocal microscope was used for real-time in vivo examination of the rabbit cornea following a cryogenic injury. The corneas of New Zealand white rabbits were frozen with a probe that had been cooled by immersion in liquid nitrogen, effectively destroying keratocytes in a central 5 mm diameter zone throughout the total thickness of the cornea. In these eyes, keratocyte repopulation and corneal stromal wound healing proceeded similarly to that which occurs after epikeratophakia, a refractive surgical procedure designed to change the curvature and optical power of the cornea. In epikeratophakia, a cryolathed donor corneal stroma lenticule is sutured onto the bare stroma of the recipient cornea. The collagen tissue lenticule is repopulated by keratocytes (corneal fibroblasts) that migrate in from the host cornea. In our study, the confocal microscope permitted sequential, noninvasive examination of the corneal stroma in the treated animals. Necrosis of the keratocytes, followed by activation of the remaining viable cells in the corneal periphery, was observed in the first 2 to 3 days after cryo injury. A fine stromal fibrous network was seen to develop; in three eyes, this network progressed to the development of a retrocorneal fibrous membrane and dense stromal fibrosis, both of which resulted in significant loss of corneal clarity. Our results suggest that the confocal microscope may be a valuable tool to provide much needed information on wound healing processes at the cellular level after corneal surgery and injury.

Animals↗