Displaying publications 1 - 20 of 244 in total

  1. Narayanasamy S, Vincent SJ, Sampson GP, Wood JM
    Clinical & experimental optometry, 2016 May;99(3):233-40.
    PMID: 26889920 DOI: 10.1111/cxo.12365
    BACKGROUND: The visual demands of modern classrooms are poorly understood yet are relevant in determining the levels of visual function required to perform optimally within this environment.

    METHODS: Thirty-three Year 5 and 6 classrooms from eight south-east Queensland schools were included. Classroom activities undertaken during a full school day (9 am to 3 pm) were observed and a range of measurements recorded, including classroom environment (physical dimensions, illumination levels), text size and contrast of learning materials, habitual working distances (distance and estimated for near) and time spent performing various classroom tasks. These measures were used to calculate demand-related minimum criteria for distance and near visual acuity, contrast and sustained use of accommodation and vergence.

    RESULTS: The visual acuity demands for distance and near were 0.33 ± 0.13 and 0.72 ± 0.09 logMAR, respectively (using habitual viewing distances and smallest target sizes) or 0.33 ± 0.09 logMAR assuming a 2.5 times acuity reserve for sustained near tasks. The mean contrast levels of learning materials at distance and near were greater than 70 per cent. Near tasks (47 per cent) dominated the academic tasks performed in the classroom followed by distance (29 per cent), distance to near (15 per cent) and computer-based (nine per cent). On average, children engaged in continuous near fixation for 23 ± 5 minutes at a time and during distance-near tasks performed fixation changes 10 ± 1 times per minute. The mean estimated habitual near working distance was 23 ± 1 cm (4.38 ± 0.24 D accommodative demand) and the vergence demand was 0.86 ± 0.07(Δ) at distance and 21.94 ± 1.09(Δ) at near assuming an average pupillary distance of 56 mm.

    CONCLUSIONS: Relatively high levels of visual acuity, contrast demand and sustained accommodative-convergence responses are required to meet the requirements of modern classroom environments. These findings provide an evidence base to inform prescribing guidelines and develop paediatric vision screening protocols and referral criteria.
    Matched MeSH terms: Visual Acuity*
  2. Yahya AN, Sit JA, Raman S
    The success of cataract surgery is accessed by the improvement in visual acuity and accuracy of the post-operation refractive outcome against the pre-operation refractive target. Hence, the benchmark of 85% of patients achieving a final spherical equivalent within 1D of the desired target is used to monitor the refractive outcome. Meanwhile, the unaided visual acuity threshold of 6/12 after cataract operation is chosen as a yardstick because it allows patients to perform instrumental activities of daily living (IADL) independently without relying on spectacles.
    Matched MeSH terms: Visual Acuity*
  3. Muzaliha MN, Nurhamiza B, Hussein A, Norabibas AR, Mohd-Hisham-Basrun J, Sarimah A, et al.
    PMID: 23055674 DOI: 10.2147/OPTH.S33270
    There is limited data in the literature concerning the visual status and skills in children with learning disabilities, particularly within the Asian population. This study is aimed to determine visual acuity and visual skills in children with learning disabilities in primary schools within the suburban Kota Bharu district in Malaysia.
    Matched MeSH terms: Visual Acuity
  4. Koh A, Lai TYY, Wei WB, Mori R, Wakiyama H, Park KH, et al.
    Retina, 2020 Aug;40(8):1529-1539.
    PMID: 31385918 DOI: 10.1097/IAE.0000000000002624
    PURPOSE: To evaluate the real-world effectiveness and safety of intravitreal ranibizumab 0.5 mg in treatment-naive patients with and without polypoidal choroidal vasculopathy (PCV).

    METHODS: Assessment of neovascular age-related macular degeneration patients with or without PCV after 12 months of ranibizumab treatment during the LUMINOUS study. Outcome measures were visual acuity and central retinal thickness changes from baseline and the rate of ocular adverse events.

    RESULTS: At baseline, 572 and 5,644 patients were diagnosed with and without PCV, respectively. The mean visual acuity gain from baseline at Month 12 in the PCV and non-PCV groups was +5.0 and +3.0 letters, respectively; these gains were achieved with a mean of 4.4 and 5.1 ranibizumab injections. Eighty percent of PCV patients and 72.2% of non-PCV patients who had baseline visual acuity ≥73 letters maintained this level of vision at Month 12; 20.6% and 17.9% of patients with baseline visual acuity <73 letters achieved visual acuity ≥73 letters in these groups. Greater reductions in central retinal thickness from baseline were also observed for the PCV group versus the non-PCV group. The rate of serious ocular adverse events was 0.7% (PCV group) and 0.9% (non-PCV group).

    CONCLUSION: LUMINOUS confirms the effectiveness and safety of ranibizumab in treatment-naive patients with PCV.

    Matched MeSH terms: Visual Acuity
  5. Abd Manan F, Jenkins TC, Collinge AJ
    Malays J Med Sci, 2001 Jul;8(2):25-31.
    PMID: 22893757 MyJurnal
    We measured stereoacuity using TNO test on 25 patients without fixation disparity (FD) and compared the result with other 25 patients exhibited FD related to visual stress. All patients were presbyopes of ages ranging from 40 to 80 years, with visual acuity 6/6 or better in each eye, free from ocular diseases and generally healthy. The results showed statistically significant difference in the stereoacuities measured between the groups (Mann-Whitney U = 181.0, p < 0.01), suggesting that FD significantly reduced stereoacuity. Although the correlation between the magnitudes of FD and stereothreshold is statistically not significant (Spearman's r(s) = 0.33, p>0.01), elimination of FD using prisms correction statistically improved stereoacuity (Wilcoxon's Z = 2.43, p<0.01). The findings conclude that visual stress manifested as FD causes deficit in stereoperformance measurable with the TNO test and can be improved by prism correction.
    Matched MeSH terms: Visual Acuity
  6. Thevi T, Sahoo S
    Med J Malaysia, 2016 Apr;71(2):45-6.
    PMID: 27326939
    PURPOSE: To analyse the visual outcomes of cases with posterior capsule rupture (PCR) compared to those without PCR following phacoemulsification. The occurrence of posterior capsule rupture during phacoemulsification surgery for cataract can have serious implications in the visual recovery. However, recognition of PCR and proper management can yield a successful visual outcome. This study analysed the visual outcomes of cases with PCR compared to those without PCR.

    METHODS: This is a case-control study. All patients who underwent cataract surgery from 2011 to 2012 in Hospital Melaka were traced from the National Eye Database (NED) of Malaysia. The visual outcomes were classified as good, borderline and poor as per WHO guidelines. The data was analysed with SPSS version 12 IBM.

    RESULTS: Out of 80.4% (2519) of eyes that had undergone phacoemulsification (PHACO) type of surgery, 3.06% (77 cases) had posterior capsule rupture complication. There was no significant difference in the visual outcome of borderline between cases with PCR and cases without PCR (Odds Ratio (OR) 0.989; 95% Confidence Interval (CI) 0.382- 2.560). However, cases with PCR were significantly less likely to have good vision compared to those without PCR (OR 0.335; 95% CI 0.157-0.714).

    CONCLUSION: The study reveals that a significant number of patients without PCR had good vision, whereas those with PCR did not get good vision. We would like to suggest meticulous care during phacoemulsification surgery to avoid PCR in order to obtain good visual outcomes.
    Matched MeSH terms: Visual Acuity*
  7. Mohammed Z, Dickinson CM
    Ophthalmic Physiol Opt, 2000 Nov;20(6):464-72.
    PMID: 11127126 DOI: 10.1111/j.1475-1313.2000.tb01124.x
    For the reading task, contrast reserve is defined as the ratio of the letter contrast of the printed letters, to the reader's contrast threshold. Acuity reserve is the ratio of the print size used for the reading task, to the reader's visual acuity. The effects of low contrast reserve on reading performance were investigated at various magnifications, ranging from 3x to 7.5x, with the field of view systematically controlled. Eye movements were recorded whilst normally sighted subjects read using the magnifiers. It was shown that with adequate contrast reserve, increasing the field of view improved the reading rate because of the resulting increase in forward saccade length. Conversely, reducing the contrast reserve slowed the reading rate by decreasing the length of forward saccades and increasing the mean fixation duration, suggesting that the perceptual span is reduced at low contrast reserve. This study also shows that when the contrast reserve is low, providing magnification higher than that required for letter recognition (that is, increasing the acuity reserve) will not improve the reading performance. Furthermore, even when the contrast reserve was high, reading rates were lower for the magnifications of 5x and higher, because increases in saccade length do not match those of the retinal image size at these magnifications.
    Matched MeSH terms: Visual Acuity/physiology*
  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.

    Matched MeSH terms: Visual Acuity/physiology*
  9. Ghoshal R, Sharanjeet-Kaur S, Mohamad Fadzil N, Mutalib HA, Ghosh S, Ngah NF, et al.
    PMID: 32887214 DOI: 10.3390/ijerph17176379
    In early and intermediate age related macular degeneration (ARMD), visual acuity alone has failed to explain the complete variation of vision. The aim of the present study was to determine correlation between different visual functions and retinal morphology in eyes with early and intermediate ARMD. In this single center cross sectional study, patients diagnosed as early or intermediate ARMD in at least one eye were recruited. Visual functions measured were best- corrected distance visual acuity (DVA), near vision acuity (NVA), reading speed (RS), and contrast sensitivity (CS). Parameters such as thickness (RT) and volume (RV) of the retina, outer retinal layer thickness (ORLT) and volume (ORLV), outer nuclear layer thickness (ONLT) and volume (ONLV), retinal pigment epithelium layer-Bruch's membrane complex thickness (RPET) and volume (RPEV) were assessed employing semi-auto segmentation method of Spectralis optical coherence tomography (OCT). Twenty-six eyes were evaluated. DVA, CS, and RS showed significantly good correlation with RPET, ONLT, and ONLV, whereas NVA showed good correlation with ONLV and RPET. The present study concluded that RS, CS, NVA, and DVA represent the morphological alteration in early stages and should be tested in clinical settings. ONLT, ONLV, and RPET morphological parameters can be employed as important biomarkers in diagnosis of early to intermediate ARMD.
    Matched MeSH terms: Visual Acuity*
  10. Yeow PT, Taylor SP
    Ophthalmic Physiol Opt, 1989 Apr;9(2):171-5.
    PMID: 2622652
    A study is made of the accuracy and repeatability of the Humphrey autorefractor (HAR) objective refraction for different refractive groups as measured against subjective refraction. The value of the autofogging mechanism in objective refraction for different refractive groupings is assessed.
    Matched MeSH terms: Visual Acuity
  11. Umi Kalthum, M.N.
    Medicine & Health, 2012;7(1):57-61.
    Dengue fever is a common pyrexial-viral infection in the Asian region and the incidence is increasing yearly. There are various ocular manifestations of dengue fever such as maculopathy, retinal hemorrhages, retinal lesions and vasculitis. Reduction in visual acuity and other visual disturbances such as metamorphopsia is the most common presentation of dengue-associated maculopathy. We report an interesting case of a young lady with bilateral maculopathy secondary to dengue fever who was managed conservatively with dramatic visual improvements. This case highlights the possibility of bilateral and simultaneous ocular involvements in patients infected with dengue fever. Both ophthalmologists and physicians need to be aware of ocular complications following dengue fever and advice patients regarding the symptoms.
    Matched MeSH terms: Visual Acuity
  12. Hopkins S, Narayanasamy S, Vincent SJ, Sampson GP, Wood JM
    Clinical & experimental optometry, 2020 05;103(3):278-289.
    PMID: 31441091 DOI: 10.1111/cxo.12953
    The role of visual acuity and refractive errors in the academic performance of children is controversial due to the variable quality of the research in this area and the mixed findings reported. This review aims to provide clarity by reviewing and critiquing relevant peer-reviewed publications and also summarises what is known regarding the visual demands of modern classroom environments. The outcomes of this review suggest that while a number of studies have investigated the role of vision in relation to children's academic performances, the veracity of the evidence obtained from the majority of these studies is undermined by methodological limitations. Comparisons between studies are constrained by differences in experimental designs, instrumentation and sample characteristics. Despite these limitations, the weight of evidence suggests there is an association between academic performance and both visual acuity and refractive error in children. However, well-designed experimental studies are necessary to further understand the relationship between these parameters.
    Matched MeSH terms: Visual Acuity
  13. Kaur S, Waheeda Azwa, Norliza Mohd Fadzil, Azrin E. Ariffin
    Sains Malaysiana, 2011;40:1325-1329.
    This study was conducted to compare the treatment outcome using patching in patients with strabismic amblyopia and refractive amblyopia. The treatment outcome was measured by visual acuity and refractive error. A total of 28 patients participated in this study. One group comprised of strabismic amblyopes who had either congenital esotropia or intermittent exotropia and spherical equivalent refractive error of less than -3.00 DS. Another group of patients were purely refractive amblyopes. Patients were first corrected with the best correction for a month. When the VA in the amblyopic eye did not improve over the month, then patching treatment was started. Patching was done daily for 2 h together with near activity. The treatment was carried out for 4 months, with the patients reviewed once every month. The results of the study revealed that VA improved by 17 alphabets or 3 lines after patching treatment for patients with strabismic amblyopia. In the refractive amblyopia group, the VA only improved by 8 alphabets or 1 line 3 alphabets. The mean spherical equivalent refractive error changed by less than -0.50DS and therefore was clinically not significant in both groups. This present study showed that patching treatment was better at improving the VA of patients with strabismic amblyopia.
    Matched MeSH terms: Visual Acuity
  14. Abd-Manan F
    Malays J Med Sci, 2000 Jul;7(2):18-26.
    PMID: 22977386 MyJurnal
    Previous studies have shown that stress on the vergence and accommodation systems, either artificially induced or naturally occurring, results in small misalignment of the visual axes, reduces binocular visual acuity and produces symptoms of ocular discomfort. This study examines the effect of artificially induced visual stress using ophthalmic prisms on three dimensional perception on 30 optometry students ages ranging from 19 to 29 years old. 6D base-in prisms, equally divided between the eyes (3D base-in each) was used to induce stress on the visual system producing misalignment of visual axes known as fixation disparity. The fixation disparity is quantified using near vision Mallett Unit and an enlarged scaled diagram. Stereoscopic perception was measured with the TNO test, with and without the presence of stress and the results was compared. Wilcoxon's matched pair ranked tests show statistically significant difference in the stereo thresholds of both conditions, p = 0.01 for advancing stereopsis and p = 0.01 for receding stereopsis, respectively. The study concludes that visual stress induced by prisms, produce misalignment of the visual axes and thus reduces three dimensional performance.
    Matched MeSH terms: Visual Acuity
  15. Woi PJ, Kaur S, Waugh SJ, Hairol MI
    F1000Res, 2016;5:1961.
    PMID: 28184281 DOI: 10.12688/f1000research.9410.1
    The human visual system is sensitive in detecting objects that have different luminance level from their background, known as first-order or luminance-modulated (LM) stimuli. We are also able to detect objects that have the same mean luminance as their background, only differing in contrast (or other attributes). Such objects are known as second-order or contrast-modulated (CM), stimuli. CM stimuli are thought to be processed in higher visual areas compared to LM stimuli, and may be more susceptible to ageing. We compared visual acuities (VA) of five healthy older adults (54.0±1.83 years old) and five healthy younger adults (25.4±1.29 years old) with LM and CM letters under monocular and binocular viewing. For monocular viewing, age had no effect on VA [F(1, 8)= 2.50, p> 0.05]. However, there was a significant main effect of age on VA under binocular viewing [F(1, 8)= 5.67, p< 0.05].  Binocular VA with CM letters in younger adults was approximately two lines better than that in older adults. For LM, binocular summation ratios were similar for older (1.16±0.21) and younger (1.15±0.06) adults. For CM, younger adults had higher binocular summation ratio (1.39±0.08) compared to older adults (1.12±0.09). Binocular viewing improved VA with LM letters for both groups similarly. However, in older adults, binocular viewing did not improve VA with CM letters as much as in younger adults. This could reflect a decline of higher visual areas due to ageing process, most likely higher than V1, which may be missed if measured with luminance-based stimuli alone.
    Matched MeSH terms: Visual Acuity
  16. Noraisyah Bt Azmi, Arifah Nur Binti Yahya, Hosana Christyon Sipon Gilong, Sit Jo Anne, Ruby Huong Yeng Ting, Nurul Hafizah Binti Amil Bangsa, et al.
    Introduction: Good visual acuity (VA) coupled with the ability to discriminate colours and having a sufficiently wide field of view are factors needed for safe driving. This study aimed to determine the types of colour vision deficiency (CVD) among failed candidates for driving license and to identify the accuracy of the Road Transport Department (RTD) screening tests in detecting those who have poor VA and CVD in Sabah.
    Matched MeSH terms: Visual Acuity
  17. Omar R, Knight VF, Hussin DA
    Med J Malaysia, 2013 Jun;68(3):245-8.
    PMID: 23749015 MyJurnal
    This study determined the outcome of combining home based and clinic based amblyopia therapy among preschool children. A total of 479 preschool children were randomly selected for vision screening. Amblyopic therapy was prescribed to children whose visual acuity (VA) could not be improved to <0.1 LogMAR after a 6 week adaptation period with glasses. Intensive near work activities were conducted daily at home for 12 weeks, monitored by parents while weekly therapy was conducted at the optometry clinic by an optometrist. Six preschool children were diagnosed with refractive amblyopia, spherical equivalent (SE) was -11.25D to +0.75D. Significant improvement was found in the VA of right eye, t(6) = 3.07, left eye t(6) = 3.07 and both eyes t(6) = 3.42) p<0.05, at the end of the 12 week therapy. Combining home based and clinic based amblyopia therapy among preschool children showed a positive improvement in VA after 12 weeks of therapy.
    Study site: kindergarten, optometry clinic, Perak (site unclear)
    Matched MeSH terms: Visual Acuity
  18. Lee MW, Lee YC
    PMID: 26107477 DOI: 10.1097/APO.0b013e318260f730
    PURPOSE: The objective of this study was to describe our initial experience with the newest refractive platform, the Wavelight Refractive Suite.
    DESIGN: This was a consecutive case series of first 50 eyes that underwent myopic laser in situ keratomileusis.
    METHODS: A total of 50 myopic eyes (28 patients) were included in this study. Uncorrected distance visual acuity, manifest refraction, and keratometry readings were taken preoperatively and 3 months postoperatively. Emmetropia was targeted with an optical zone of 6.5 mm, and flap dimensions were of 130-μm thickness and 9-mm diameter with a superior hinge in all eyes. Flap thickness was measured with optical coherence tomography postoperatively.
    RESULTS: At 3 months postoperatively, 82% (41/50) of eyes achieved uncorrected distance visual acuity of 6/6 or better, 98% (49/50) achieved 6/9 or better, and all eyes achieved 6/12 or better. Eighty-four percent of eyes were within 0.5 diopter (D) of target of emmetropia, and 98% of eyes were within 1 D. Mean postoperative flap thickness was 124 ± 7.8 μm.
    CONCLUSIONS: The Wavelight Refractive Suite consisting of the femtosecond laser FS200 and Excimer laser EX500 is the newest integrated refractive surgical platform available and can offer good refractive predictability as shown by the results in our initial 50 myopic eyes.
    Matched MeSH terms: Visual Acuity
  19. Lim TK
    Med J Malaysia, 1984 Sep;39(3):205-9.
    PMID: 6544921
    50 cases of anterior chamber intraocular lens implantation at the University Hospital, Kuala Lumpur were studied. 80% of the cases achieved visual acuity of 6/9 or better. The percentage would be higher if cases with pre-existing pathology are excluded and the period of follow-up is longer. Complications, mainly minor and non sight-threatening, are discussed.
    Matched MeSH terms: Visual Acuity
  20. Then SM, Chandran S
    Med J Malaysia, 1975 Mar;30(3):180-6.
    PMID: 1160676
    Matched MeSH terms: Visual Acuity
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