Displaying all 18 publications

  1. Zahari M, Ong YM, Taharin R, Ramli N
    Optom Vis Sci, 2014 Apr;91(4):459-63.
    PMID: 24637481 DOI: 10.1097/OPX.0000000000000220
    To evaluate ocular biometric parameters and darkroom prone provocative test (DPPT) in family members of primary angle closure (PAC) glaucoma (PACG) patients and to establish any correlation between these biometric parameters and the DPPT response.
  2. Price H, Allen PM, Radhakrishnan H, Calver R, Rae S, Theagarayan B, et al.
    Optom Vis Sci, 2013 Nov;90(11):1274-83.
    PMID: 24100478 DOI: 10.1097/OPX.0000000000000067
    To identify variables associated with myopia progression and to identify any interaction between accommodative function, myopia progression, age, and treatment effect in the Cambridge Anti-Myopia Study.
  3. Efron N, Morgan PB, Woods CA, International Contact Lens Prescribing Survey Consortium
    Optom Vis Sci, 2013 Feb;90(2):113-8.
    PMID: 23262991 DOI: 10.1097/OPX.0b013e31827cd8be
    PURPOSE: To determine the extent of rigid contact lens fitting worldwide and to characterize the associated demographics and fitting patterns.
    METHODS: Survey forms were sent to contact lens fitters in up to 40 countries between January and March every year for five consecutive years (2007 to 2011). Practitioners were asked to record data relating to the first 10 contact lens fits or refits performed after receiving the survey form. Survey data collected between 1996 and 2011 were also analyzed to assess rigid lens fitting trends in seven nations during this period.
    RESULTS: Data were obtained for 12,230 rigid and 100,670 soft lens fits between 2007 and 2011. Overall, rigid lenses represented 10.8% of all contact lens fits, ranging from 0.2% in Lithuania to 37% in Malaysia. Compared with soft lens fits, rigid lens fits can be characterized as follows: older age (rigid, 37.3 ± 15.0 years; soft, 29.8 ± 12.4 years); fewer spherical and toric fits; more bifocal/multifocal fits; less frequent replacement (rigid, 7%; soft, 85%); and less part-time wear (rigid, 4%; soft, 10%). High-Dk (contact lens oxygen permeability) (36%) and mid-Dk (42%) materials are predominantly used for rigid lens fitting. Orthokeratology represents 11.5% of rigid contact lens fits. There has been a steady decline in rigid lens fitting between 1996 and 2011.
    CONCLUSIONS: Rigid contact lens prescribing is in decline but still represents approximately 10% of all contact lenses fitted worldwide. It is likely that rigid lenses will remain as a viable, albeit increasingly specialized, form of vision correction.
  4. Efron N, Morgan PB, Woods CA, International Contact Lens Prescribing Survey Consortium
    Optom Vis Sci, 2012 Feb;89(2):122-9.
    PMID: 22179218
    PURPOSE: To determine the extent of extended wear (EW) contact lens prescribing worldwide and to characterize the associated demographics and fitting patterns.
    METHODS: Up to 1000 survey forms were sent to contact lens fitters in up to 39 countries between January and March every year for five consecutive years (2006-2010). Practitioners were asked to record data relating to the first 10 contact lens fits or refits performed after receiving the survey form. Survey data collected since 1997 was also analyzed to assess EW fitting trends since that time.
    RESULTS: Details for lens modality were received for 107,094 rigid and soft lens fits of which 88,392 were for soft lens daily wear (DW) and 7470 were for soft lens EW. Overall, EW represents 7.8% of all soft lens fits, ranging from 0.6% in Malaysia to 27% Norway. Compared with DW fittings, EW fittings can be characterized as follows: older age (32.7 ± 13.6 vs. 29.4 ± 12.0 years for DW); males are over-represented; greater proportion of refits; 72% silicone hydrogel; higher proportion of presbyopia and spherical designs; and higher proportion of monthly lens replacement. Of those wearing EW lenses, 80% use multipurpose solutions, whereas 9% do not use any care system. Between 1997 and 1999, the rate of EW prescribing decreased from 5 to 1% of all soft lens fits; it increased to a peak of 12% in 2006, and settled back to 8% by 2010.
    CONCLUSIONS: EW prescribing has failed to break through the "glass ceiling" of 15% and is unlikely to become a mainstream lens wearing modality until the already low risks of ocular complications can be reduced to be equivalent to that for DW.
  5. Ramli N, Supramaniam G, Samsudin A, Juana A, Zahari M, Choo MM
    Optom Vis Sci, 2015 Sep;92(9):e222-6.
    PMID: 25730335 DOI: 10.1097/OPX.0000000000000542
    PURPOSE: To evaluate the prevalence of ocular surface disease (OSD) in glaucoma and nonglaucoma subjects using different clinical tests and to determine the effect of number of antiglaucoma medications and preservatives on OSD.
    METHODS: This is a cross-sectional, case-comparison study at the Eye Clinic of the University of Malaya Medical Centre, Malaysia, between June 2012 and January 2013. Glaucoma subjects (n = 105) using topical antiglaucoma medications were compared with control subjects (n = 102) who were not on any topical medications. The presence of OSD was assessed using the tear film breakup time (TBUT) test, corneal staining, Schirmer test, and Ocular Surface Disease Index (OSDI) questionnaire grading.
    RESULTS: The prevalence of OSD varied from 37 to 91% in the glaucoma group, depending on the type of clinical test. More subjects in the glaucoma group had corneal staining (63% vs. 36%, p = 0.004), abnormal Schirmer tests (39% vs. 25%, p = 0.049), and moderate OSDI symptoms (17% vs. 7%, p = 0.028). The percentage with abnormal TBUT increased with higher numbers of topical medications and was high with both benzalkonium chloride-containing and preservative-free eye drops (90% and 94%, respectively, both p < 0.001). Benzalkonium chloride was associated with a nearly three times higher odds ratio of showing abnormal OSDI.
    CONCLUSIONS: Ocular surface disease is common in those using topical antiglaucoma medications. Abnormal TBUT is associated with increasing number of eye drops and benzalkonium chloride-containing eye drops, although this also occurs with the use of preservative-free eye drops.
    Study site: Eye Clinic, University of Malaya Medical Centre (UMMC), Kuala Lumpur, Malaysia,
  6. Ismail F, Peyman M, Waran V, Vasudevan S, Subrayan V
    Optom Vis Sci, 2015 Apr;92(4 Suppl 1):S33-5.
    PMID: 25730333 DOI: 10.1097/OPX.0000000000000528
    To report a rare case of nasal chondroma presenting as hypertelorism.
  7. Nadarajah S, Samsudin A, Ramli N, Tan CT, Mimiwati Z
    Optom Vis Sci, 2017 10;94(10):981-985.
    PMID: 28858045 DOI: 10.1097/OPX.0000000000001117
    SIGNIFICANCE: To our knowledge, this is the first time a study looking at the association between corneal hysteresis (CH) and obstructive sleep apnea syndrome (OSAS) severity has been reported. We provide evidence that CH is lower in OSAS and speculate on the possible causes.

    PURPOSE: The present study aims to look at the association between CH and severity of OSAS, and whether CH could be another link between OSAS and the development of glaucoma.

    METHODS: This was a cross-sectional, observational study at the University Malaya Medical Centre, Kuala Lumpur. Patients undergoing polysomnography for assessment of OSAS were recruited. We measured central corneal thickness (CCT) using optical biometry, and CH using ocular response analysis. Intraocular pressure (IOP) and Humphrey visual field (HVF) indices were also measured. The Apnea Hypopnea Index (AHI) divided patients into normal, mild, moderate, and severe OSAS categories. The normal and mild categories (47.9%) were then collectively called group 1, and the moderate and severe categories (52.1%) were called group 2. T tests, Pearson correlation tests, and general linear model analysis were performed, with P .05). CH correlated negatively with AHI (r = -0.229, P = .013) and positively with lowest oxygen saturation (r = 0.213, P = .022).

    CONCLUSIONS: CH is lower in moderate/severe OSAS than in normal/mild cases. This may be another link between OSAS and the development of glaucoma; further studies are indicated to determine the significance of this connection.

  8. Sailoganathan A, Rou LX, Buja KA, Siderov J
    Optom Vis Sci, 2018 08;95(8):643-647.
    PMID: 30063661 DOI: 10.1097/OPX.0000000000001253
    SIGNIFICANCE: Vision charts comprising single Lea symbols surrounded by either flanking bars or flanking Lea symbols are available for measurement of visual acuity in children. However, the results obtained with such charts may not be interchangeable owing to potential differences in the crowding effect.

    PURPOSE: The purpose of this study was to compare habitual visual acuity in a sample of young children using two versions of the single Lea symbols charts with different crowding features.

    METHODS: Monocular habitual visual acuity was measured in a sample of 77 young children aged between 4 and 6 years using crowded Lea symbols charts with either flanking bars separated from the central symbol by 0.5 optotype width or flanking Lea optotypes separated from the central symbol by 1.0 optotype width.

    RESULTS: Mean visual acuity was higher (i.e., lower logarithm of the minimum angle of resolution) with the Lea symbols crowded using flanking optotypes, equivalent to about 1.5 optotype difference. Visual acuity measured with the two charts was significantly correlated; however, the 95% limits of agreement were larger than expected from repeatability studies using Lea symbols.

    CONCLUSIONS: Lea symbols with flanking optotypes resulted in higher visual acuity than the Lea symbols with flanking bars, probably as a result of differences in the crowding effect. The two charts showed insufficient agreement, and we do not recommend their use interchangeably. We recommend using the Lea symbols with flanking bars because of the closer flanker-target separation.

  9. Chung KM, Mohidin N, Yeow PT, Tan LL, O'Leary D
    Optom Vis Sci, 1996 Nov;73(11):695-700.
    PMID: 8950751
    We performed a vision screening of 1883 Chinese schoolchildren from 4 schools around Kuala Lumpur in June 1990. The group contained 1083-males and 800 females. Visual acuity, refractive error, oculomotor balance, and axial length were measured. The prevalence of myopia in Chinese schoolchildren was found to be 37% in the 6- to 12-year age group and 50% in the 13- to 18-year age group. Approximately 63% of the sample had unaided visual acuity of 6/6 or better and 24% had unaided acuity of 6/12 or worse. Six hundred twenty-five students (33%) failed the vision screening test and were referred for further examinations. The group which failed the vision screening test and had the highest rate of referral (46%) was the 11- to 12-year-old age group. The most common visual disorder was uncorrected myopia, accounting for 38% of the referrals (235 students). Only 26% of the sample were wearing a spectacle correction.
  10. Chung KM
    Optom Vis Sci, 1993 Mar;70(3):228-33.
    PMID: 8483585
    Studies of optical defocus on refractive development and ocular growth in animals are presented and discussed in relation to the accommodation hypothesis. None of these studies fully support the accommodation hypothesis. The problems encountered in these studies are also discussed.
  11. Chung KM
    Optom Vis Sci, 1999 Feb;76(2):121-6.
    PMID: 10082059
    The clinical significance of fundus magnification produced during direct ophthalmoscopy of the corrected eye has not been fully established. Based on paraxial ray tracing, fundus magnification (M) can be defined by a simple equation, M = (K'/4) x (Fs/K), where K' is the dioptric axial power of the eye, Fs is the correcting thin lens power and K is the ocular ametropia. Refractive myopes produce greater fundus magnification than axial myopes, whereas refractive hyperopes produce lower fundus magnification than axial hyperopes. If we assume 15 x fundus magnification as our standard magnification for an emmetropic reduced eye, then wearing glasses or putting the focusing lens at or close to the anterior focus of the eye is able to achieve the standard magnification for axial myope and axial hyperope, whereas wearing contact lenses is able to achieve the standard magnification for refractive myope and refractive hyperope. Vertex distance has greater influence on fundus magnification produced during direct ophthalmoscopy than other funduscopic techniques. In conclusion, the newly defined formula has clinical applications during direct ophthalmoscopy.
  12. Ong BL
    Optom Vis Sci, 1996 Mar;73(3):208-10.
    PMID: 8725025
    This study attempted to determine whether contact lens wear has any adverse effect on the Meibomian glands. The study also tried to elucidate the prevalence of Meibomian gland dysfunction in the general population. The results of the study showed that Meibomian gland dysfunction exists in 43% of the population (lens wearers and nonlens wearers), 49% of the contact lens wearing population (81 subjects), and 39% of nonlens wearers (150 subjects). No statistically significant difference was found in the prevalence of Meibomian gland dysfunction between healthy contact lens wearers and the control group of nonlens wearers. The study therefore could not prove that contact lens wear is a contributing factor to Meibomian gland dysfunction.
  13. Yeow PT, Taylor SP
    Optom Vis Sci, 1991 Dec;68(12):930-41.
    PMID: 1787950
    Since their rapid introduction into the workplace visual display terminals (VDT's) have been the source of a number of studies aimed at detecting effects on office workers. The published studies have been either short-term or cross-sectional, with one exception. The results have shown varying degrees of relation but by not having a comparable control group all have been limited in their value. We set out to monitor at regular intervals over a 2-year period specific visual functions that have been reported to be affected by VDT usage, and to compare VDT and non-VDT users in the same office environment. By assessing the VDT operators from the time the systems were introduced we have an accurate baseline to work from when assessing change due to the introduction of the VDT.
  14. Yeow PT, Taylor SP
    Optom Vis Sci, 1989 Jul;66(7):459-66.
    PMID: 2771333
    An on-site comparative study was carried out on the effects of video display terminal (VDT) and non-VDT work on visual functions in two working populations in the same office environment. Both continuous VDT usage in a training situation over a few days and intermittent VDT usage in a normal working situation were assessed and particular attention paid to their effects on the refractive error of different refractive groups and for different age populations. Other visual functions measured were visual acuity (VA), accommodation, and convergence. Results show that VDT work does not have a significantly greater effect on visual function than non-VDT work.
  15. Md Isa NA, Koh PY, Doraj P
    Optom Vis Sci, 2019 09;96(9):678-685.
    PMID: 31479023 DOI: 10.1097/OPX.0000000000001422
    SIGNIFICANCE: Prominent ocular surface dryness and poor tear film quality among electronic cigarette (e-cigarette) smokers (or vapers) indicate potential harm to the eyes from vaping. These findings may serve as precautionary signs for e-cigarette users and exposed bystanders.

    PURPOSE: Little is known about the effect of e-cigarettes on the eyes except for reported eye irritation among individuals who were exposed to e-cigarette vapors and e-liquids. This study aims to investigate the effect of vaping on ocular surface health of long-term vapers.

    METHODS: Twenty-one vapers and 21 healthy nonsmokers who are all male underwent measurements of the Ocular Surface Disease Index, noninvasive tear breakup time, fluorescein breakup time, ocular surface staining, tear meniscus height, and the Schirmer test. The effect of voltage used during vaping was also evaluated against the measurements.

    RESULTS: Vapers experienced moderate-to-severe eye dryness (25.0 [interquartile range, 14.6 to 43.7]) as indicated by the Ocular Surface Disease Index. Significant reductions of noninvasive tear breakup time (3.13 ± 0.97 vs. 6.57 ± 2.31 seconds; P < .0001), fluorescein breakup time (2.68 [interquartile range, 2.33 to 3.18] vs. 4.12 [3.56 to 5.07] seconds; P < .0001), and tear meniscus height (203.0 [193.0 to 225.5] vs. 235.0 [210.0 to 253.50] μm; P = .002) were noted in vapers, but the Schirmer test showed higher results (14.5 [12.0 to 17.0] vs. 8.0 [7.0 to 11.0] mm; P = .001) compared with nonsmokers. Increase in vaping voltage aggravated the dry eye symptoms and tear instability (P < .05). Higher Schirmer test result was also noted as voltage increases.

    CONCLUSIONS: Vapers showed moderate-to-severe symptomatic dry eye and poorer tear film quality compared with nonsmokers. High vaping voltage may have aggravated the dry eye syndrome because of hazardous by-products from pyrolysis of the e-liquid constituents. Investigation of the ocular surface health at cellular and molecular levels is warranted to gain a deeper understanding on the effect of e-cigarette to the eyes.

  16. Wu HM, Seet B, Yap EP, Saw SM, Lim TH, Chia KS
    Optom Vis Sci, 2001 Apr;78(4):234-9.
    PMID: 11349931
    PURPOSE: To study interethnic variation in myopia prevalence and severity in young adult males in Singapore and to determine whether these variations are related to differences in education level.

    METHODS: A population-based survey of refractive errors in a cohort of 15,095 military conscripts between July 1996 and June 1997 using noncycloplegic autorefraction and a standard questionnaire. Prevalence rates of myopia (

  17. Amil-Bangsa NH, Mohd-Ali B, Ishak B, Abdul-Aziz CNN, Ngah NF, Hashim H, et al.
    Optom Vis Sci, 2019 12;96(12):934-939.
    PMID: 31834153 DOI: 10.1097/OPX.0000000000001456
    SIGNIFICANCE: Total protein concentration (TPC) and tumor necrosis factor α (TNF-α) concentration in tears are correlated with severity of retinopathy. However, minimal data are available in the literature for investigating tear TPC and TNF-α concentrations in Asian individuals with different severity of nonproliferative diabetic retinopathy (NPDR).

    PURPOSE: This study evaluated differences of TPC and TNF-α concentrations in tears at different severity of NPDR among participants with diabetes in comparison with normal participants.

    METHODS: A total of 75 participants were categorized based on Early Treatment for Diabetic Retinopathy Study scale, with 15 participants representing each group, namely, normal, diabetes without retinopathy, mild NPDR, moderate NPDR, and severe NPDR. All participants were screened using McMonnies questionnaire. Refraction was conducted subjectively. Visual acuity was measured using a LogMAR chart. Twenty-five microliters of basal tears was collected using glass capillary tubes. Total protein concentration and TNF-α concentrations were determined using Bradford assay and enzyme-linked immunosorbent assay, respectively.

    RESULTS: Mean ± SD age of participants (n = 75) was 57.88 ± 4.71 years, and participants scored equally in McMonnies questionnaire (P = .90). Mean visual acuity was significantly different in severe NPDR (P = .003). Mean tear TPC was significantly lower, and mean tear TNF-α concentration was significantly higher in moderate and severe NPDR (P < .001). Mean ± SD tear TPC and TNF-α concentrations for normal were 7.10 ± 1.53 and 1.39 ± 0.24 pg/mL; for diabetes without retinopathy, 6.37 ± 1.65 and 1.53 ± 0.27 pg/mL; for mild NPDR, 6.32 ± 2.05 and 1.60 ± 0.21 pg/mL; for moderate NPDR, 3.88 ± 1.38 and 1.99 ± 0.05 pg/mL; and for severe NPDR, 3.64 ± 1.26 and 2.21 ± 0.04 pg/mL, respectively. Tear TPC and TNF-α concentrations were significantly correlated (r = -0.50, P < .0001). Visual acuity was significantly correlated with tear TPC (r = -0.236, P = .04) and TNF-α concentrations (r = 0.432, P < .0001).

    CONCLUSIONS: This cross-sectional study identified differences in tear TPC and TNF-α concentrations with increasing severity of NPDR.

  18. Sharudin SN, Saaid R, Samsudin A, Mohamad NF
    Optom Vis Sci, 2020 Feb;97(2):81-85.
    PMID: 32011579 DOI: 10.1097/OPX.0000000000001480
    SIGNIFICANCE: To our knowledge, this is the first time a study looking at the association between subfoveal choroidal thickness (SFCT) and the parameters affecting the severity of pre-eclampsia has been reported. We provide evidence that SFCT is thicker in pre-eclamptic (PE) patients and speculate on the possible causes.

    PURPOSE: The purposes of this study were to compare SFCT in PE, normal pregnant, and nonpregnant women using spectral domain optical coherence tomography and to correlate SFCT with severity of pre-eclampsia.

    METHODS: A cross-sectional, observational study was performed. A total of 150 participants were divided into three groups: group 1 (50 PE women), group 2 (50 normal pregnant women), and group 3 (50 nonpregnant healthy women). Subfoveal choroidal thickness was measured using spectral domain optical coherence tomography. Other parameters including mean arterial blood pressure (MABP), central corneal thickness, macular thickness, IOP, ocular perfusion pressure (OPP), and urine protein-to-creatinine ratio were also measured. ANOVA and Pearson correlation analysis were used to look at differences between the groups. P < .05 was considered as statistically significant.

    RESULTS: The MABP was higher in group 1 than in groups 2 and 3 (103.0 ± 12.9 vs. 83.2 ± 9.8 vs. 89.5 ± 7.2 mmHg, respectively; all P < .001). The SFCT of the PE group was higher than in groups 2 and 3 (370.7 ± 23.8 vs. 344.5 ± 30.8 vs. 315.8 ± 49.9 μm, respectively; all P < .001). There were no statistically significant differences in central corneal thickness, macular thickness, or IOP between the PE and healthy pregnant groups (all P > .05). The OPP was greater in PE patients (52.8 ± 8.5 vs. 41.9 ± 6.9 vs. 43.4 ± 5.2 mmHg, respectively; both P < .001). The SFCT was positively correlated with MABP (r = 0.464, P < .001), OPP (r = 0.495, P < .001), and urine protein-to-creatinine ratio (r = 0.635, P < .001) in the PE group.

    CONCLUSIONS: Subfoveal choroidal thickness is higher in pre-eclampsia and is proportional to established markers of severity of the condition. This parameter might serve as a novel predictive marker for the severity of pre-eclampsia.

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