Displaying publications 21 - 31 of 31 in total

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  1. Radhakrishnan H, Hartwig A, Charman WN, Llorente L
    Clin Exp Optom, 2015 Nov;98(6):527-34.
    PMID: 26450168 DOI: 10.1111/cxo.12296
    BACKGROUND: Differences in accommodation when reading Chinese, as compared to Latin, characters have been suggested to have a role in the higher prevalence of myopia in some Asian countries. Yeo and colleagues (Optom Vis Sci 2013; 90: 156-163) found that, in Chinese-literate children, accommodation was marginally more accurate (by less than 0.05 D), when reading Chinese text. This was attributed to the additional cognitive demand associated with interpreting the more complex Chinese symbols. The present study compared responses to single Chinese and Latin characters, while controlling for cognitive demand.
    METHODS: The monocular accommodative response was measured in Chinese-illiterate adults (10 emmetropes, mean spherical equivalent: -0.07 ± 0.42 D, age: 29.9 ± 4.2 years; 11 myopes, mean spherical equivalent: -4.28 ± 2.84 D, age: 31.7 ± 4.6 years) with an open-field autorefractor. Four Chinese and three Latin characters (approximately 1.15 degrees subtense) were individually presented on a display screen one metre away from the subject, while their vergence was varied over the range zero to 5.00 D using spectacle trial lenses. The slope and the accommodative error index (AEI) were calculated from the accommodative stimulus/response curves (ASRC).
    RESULTS: No statistically significant differences were found between refractive groups or among characters within the same refractive group in ARSC slopes (Latin: 0.87 ± 0.14 for myopes versus 0.81 ± 0.12 for emmetropes; Chinese: 0.84 ± 0.12 for myopes versus 0.85 ± 0.12 for emmetropes). No significant differences were found between characters in accommodative error index either (Latin, 0.78 ± 0.42 D for myopes versus 1.15 ± 0.72 D for emmetropes; Chinese, 0.74 ± 0.37 D for myopes versus 1.17 ± 0.83 D for emmetropes). However, accommodative error indices and accommodative errors were significantly higher for emmetropes.
    CONCLUSION: Under controlled cognitive demand, Chinese and Latin characters elicited similar responses in both individual refractive groups. This study fails to support the hypothesis that development of myopia in some Asian populations is associated with larger lags of accommodation when reading or viewing Chinese characters.
    Study site: Manchester, United Kingdom
    Matched MeSH terms: Refraction, Ocular/physiology*
  2. Lee MW
    Int Ophthalmol, 2024 Jul 24;44(1):334.
    PMID: 39046597 DOI: 10.1007/s10792-024-03247-x
    PURPOSE: To evaluate the clinical outcomes following bilateral implantation of the AcrySof™ IQ Vivity™ toric extended depth of focus (EDOF) intraocular lens (IOL).

    DESIGN: Prospective interventional case series.

    METHODS: Patients with bilateral significant cataracts and pre-existing corneal astigmatism underwent cataract surgery and implantation with the AcrySof™ IQ Vivity™ toric IOL. Dominant eyes were targeted at emmetropia and non-dominant eyes at -0.50D. Primary endpoints were binocular uncorrected distance (UDVA), intermediate (UIVA at 66 cm) and near (UNVA at 40 cm) acuities at 3 months. Secondary outcomes were corrected distance (CDVA), distance corrected intermediate (DCIVA) and distance corrected near (DCNVA), refractive predictability, rotational stability, binocular defocus curve, contrast sensitivity, Questionnaire for Visual Disturbances (QUVID) and Visual Function Index (VF-14) questionnaire scores. All visual acuities were converted to logarithm of minimum angle of resolution (logMAR) for analysis.

    RESULTS: 30 patients underwent uneventful phacoemulsification. The mean binocular UDVA, UIVA and UNVA were 0.06 ± 0.12, 0.11 ± 0.10 and 0.26 ± 0.10 respectively. The mean refractive spherical equivalent (MRSE) for dominant and non-dominant eyes were - 0.07D ± 0.27 and - 0.12D ± 0.54 respectively. 92.4% of dominant eyes and 84.6% of non-dominant eyes within 0.50D of target. The mean IOL rotation was 3.85° ± 5.09 with 86.7% of eyes with less than 5° of rotation. 26.7%, 20% and 36.7% of patients reported starbursts, haloes and glare respectively. The mean VF-14 score was 91.77.

    CONCLUSION: Bilateral implantation of the AcrySof™ IQ Vivity™ Toric IOL resulted in very good unaided visual acuities for far and intermediate distance with functional near vision. Dysphotopsias were reported but despite this, a high level of visual function was achieved.

    Matched MeSH terms: Refraction, Ocular/physiology
  3. Wu AL, Ling KP, Chuang LH, Chen KJ, Chen YP, Yeung L, et al.
    Acta Ophthalmol, 2020 Nov;98(7):e839-e847.
    PMID: 32243725 DOI: 10.1111/aos.14418
    PURPOSE: To investigate the long-term surgical outcomes of macular hole retinal detachment (MHRD) following vitrectomy with macular plug in highly myopic eyes.

    METHODS: Thirty-five cases of highly myopic eyes with MHRD in 35 patients who underwent an initially successful vitrectomy with macular plug and were followed up for at least 3 years were reviewed. The anatomical outcomes were evaluated by fundus examination, fundus photographs and optical coherence tomography (OCT). Myopic features after the surgery were differentiated according to recommendations of the Meta-analysis of Pathologic Myopia (META-PM) Study Group. The best-corrected visual acuities (BCVAs) before and after surgery were analysed as the functional outcome. Main outcome measures time-course changes in BCVA and complications.

    RESULTS: The mean patient age was 61.0 ± 11.4 years. The follow-up was 45.2 ± 8.6 months (ranged from 36 to 71 months). The mean axial length was 29.3 ± 1.2 mm. All eyes demonstrated attached retina, but 2 eyes (5.7%) developed reopened macular holes until the last follow-up. Complications of postoperative rhegmatogenous retinal detachment were detected in 2 eyes (5.7%) within 1 year and retina reattached after the secondary vitrectomy. Three cases (8.6%) of prolonged subretinal fluid lasting more than 1 year were detected but finally absorbed completely. Comparing 1-3 years postoperatively, myopic features showed significant progression of myopic maculopathy category (p = 0.035). Functionally, significantly improved BCVA could be maintained postoperatively between 6 months and 3 years. However, vision of 14 eyes (40.0%) worsened within 1-3 years postoperatively, and visual deterioration was associated with progression of myopic maculopathy (p = 0.004) and pre-existing disease of glaucoma (p = 0.006).

    CONCLUSIONS: A vitrectomy combined with macular plug provided favourable outcomes in the long term, over the ≥3-year follow-up period.

    Matched MeSH terms: Refraction, Ocular/physiology*
  4. Fam HB, Lim KL
    J Cataract Refract Surg, 2006 Aug;32(8):1281-7.
    PMID: 16863962 DOI: 10.1016/j.jcrs.2006.02.060
    PURPOSE: To determine an index that distinguishes keratoconus and keratoconus-suspect eyes from normal eyes with Orbscan (Bausch & Lomb) corneal elevation maps.
    SETTING: Department of Ophthalmology, Tan Tock Seng Hospital, Singapore, and iLaser Centre, Island Hospital, Penang, Malaysia.
    METHODS: In this initial phase of this multicenter nonrandomized retrospective study, 1 eye of 166 normal subjects, 15 keratoconus patients, and 11 keratoconus suspects was examined at 1 clinic. The anterior best-fit sphere (BFS), posterior BFS, anterior elevation, posterior elevation, and maximum and minimum keratometries were analyzed. Two indices with the highest sensitivity and specificity classifying these conditions were identified using receiver operating characteristic curves. These 2 indices were evaluated in a subsequent validation study using 1 eye of 221 normal subjects, 43 keratoconus patients, and 23 keratoconus suspects from another clinic.
    RESULTS: The anterior elevation and anterior elevation ratio (anterior elevation ratio = anterior elevation/anterior BFS) best classified the different groups. An anterior elevation ratio of 0.5122 mm or less had 99% sensitivity and 95.2% specificity while a ratio 16.5 mum or less had 80.1% sensitivity and 80.8% specificity in discriminating normal eyes from keratoconus and keratoconus suspects. The results were similar in the validation study. In addition, these anterior elevation and anterior elevation ratio cutoff values had high sensitivity and specificity in identifying keratoconus suspects from normal eyes in the validation study.
    CONCLUSION: Anterior corneal elevation parameters are clinically relevant measures for detecting keratoconus and suspected keratoconus eyes.
    Matched MeSH terms: Refraction, Ocular
  5. Goh PP, Abqariyah Y, Pokharel GP, Ellwein LB
    Ophthalmology, 2005 Apr;112(4):678-85.
    PMID: 15808262 DOI: 10.1016/j.ophtha.2004.10.048
    To assess the prevalence of refractive error and visual impairment in school-age children in Gombak District, a suburban area near Kuala Lumpur city.
    Matched MeSH terms: Refraction, Ocular
  6. 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 (

    Matched MeSH terms: Refraction, Ocular
  7. 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.
    Matched MeSH terms: Refraction, Ocular
  8. Mohd Radzi H, Khairidzan MK, Mohd Zulfaezal CA, Azrin EA
    J Optom, 2019 05 13;12(4):272-277.
    PMID: 31097348 DOI: 10.1016/j.optom.2019.04.001
    PURPOSE: To describe an objective method to accurately quantify corneo-pterygium total area (CPTA) by utilising image analysis method and to evaluate its association with corneal astigmatism (CA).

    METHODS: 120 primary pterygium participants were selected from patients who visited an ophthalmology clinic. We adopted image analysis software in calculating the size of invading pterygium to the cornea. The marking of the calculated area was done manually, and the total area size was measured in pixel. The computed area is defined as the area from the apex of pterygium to the limbal-corneal border. Then, from the pixel, it was transformed into a percentage (%), which represents the CPTA relative to the entire corneal surface area. Intra- and inter-observer reliability testing were performed by repeating the tracing process twice with a different sequence of images at least one (1) month apart. Intraclass correlation (ICC) and scatter plot were used to describe the reliability of measurement.

    RESULTS: The overall mean (N=120) of CPTA was 45.26±13.51% (CI: 42.38-48.36). Reliability for region of interest (ROI) demarcation of CPTA were excellent with intra and inter-agreement of 0.995 (95% CI, 0.994-0.998; P<0.001) and 0.994 (95% CI, 0.992-0.997; P<0.001) respectively. The new method was positively associated with corneal astigmatism (P<0.01). This method was able to predict 37% of the variance in CA compared to 21% using standard method.

    CONCLUSIONS: Image analysis method is useful, reliable and practical in the clinical setting to objectively quantify actual pterygium size, shapes and its effects on the anterior corneal curvature.

    Matched MeSH terms: Refraction, Ocular
  9. Au Eong KG, Tay TH, Lim MK
    Singapore Med J, 1993 Dec;34(6):489-92.
    PMID: 8153707
    Computerised data of 110,236 Singaporean males aged 15 to 25 (mean 17.75) years who underwent compulsory medical examination from April 1987 to January 1992 were used to estimate the prevalence and severity of myopia among young Chinese, Malay, Indian and Eurasian Singaporean males with different educational levels. The prevalence and severity of myopia amongst the groups with different educational levels were compared. These groups were fairly well-matched for important known confounding factors such as age, sex, race and degree of urbanisation of place of residence. Our data showed a positive association between educational attainment and both the prevalence and severity of myopia. Both the prevalence of myopia and the proportion of myopes with severe myopia were in general higher among those with more years of formal education.
    Matched MeSH terms: Refraction, Ocular
  10. Hashim SE, Tan HK, Wan-Hazabbah WH, Ibrahim M
    Ann Acad Med Singap, 2008 Nov;37(11):940-6.
    PMID: 19082201
    INTRODUCTION: Refractive error remains one of the primary causes of visual impairment in children worldwide, and the prevalence of refractive error varies widely. The objective of this study was to determine the prevalence of refractive error and study the possible associated factors inducing refractive error among primary school children of Malay ethnicity in the suburban area of Kota Bharu, Kelantan, Malaysia.

    MATERIALS AND METHODS: A school-based cross-sectional study was performed from January to July 2006 by random selection on Standard 1 to Standard 6 students of 10 primary schools in the Kota Bharu district. Visual acuity assessment was measured using logMAR ETDRS chart. Positive predictive value of uncorrected visual acuity equal or worse than 20/40, was used as a cut-off point for further evaluation by automated refraction and retinoscopic refraction.

    RESULTS: A total of 840 students were enumerated but only 705 were examined. The prevalence of uncorrected visual impairment was seen in 54 (7.7%) children. The main cause of the uncorrected visual impairment was refractive error which contributed to 90.7% of the total, and with 7.0% prevalence for the studied population. Myopia is the most common type of refractive error among children aged 6 to 12 years with prevalence of 5.4%, followed by hyperopia at 1.0% and astigmatism at 0.6%. A significant positive correlation was noted between myopia development with increasing age (P <0.005), more hours spent on reading books (P <0.005) and background history of siblings with glasses (P <0.005) and whose parents are of higher educational level (P <0.005). Malays in suburban Kelantan (5.4%) have the lowest prevalence of myopia compared with Malays in the metropolitan cities of Kuala Lumpur (9.2%) and Singapore (22.1%).

    CONCLUSION: The ethnicity-specific prevalence rate of myopia was the lowest among Malays in Kota Bharu, followed by Kuala Lumpur, and is the highest among Singaporean Malays. Better socio-economic factors could have contributed to higher myopia rates in the cities, since the genetic background of these ethnic Malays are similar.

    Matched MeSH terms: Refraction, Ocular
  11. Mahmud I, Kelley T, Stowell C, Haripriya A, Boman A, Kossler I, et al.
    JAMA Ophthalmol, 2015 Nov;133(11):1247-52.
    PMID: 26291752 DOI: 10.1001/jamaophthalmol.2015.2810
    Aligning outcome measures for cataract surgery, one of the most frequently performed procedures globally, may facilitate international comparisons that can drive improvements in the outcomes most meaningful to patients.
    Matched MeSH terms: Refraction, Ocular
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