Displaying all 11 publications

Abstract:
Sort:
  1. 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: Contrast Sensitivity/physiology
  2. Bhandari M, Wei Ern RL, Majumder C, Ho D
    Med J Malaysia, 2019 02;74(1):30-33.
    PMID: 30846659
    PURPOSE: To determine the effects of ChromaGen blue filter lens in reading speed, accuracy and contrast sensitivity.

    METHODS: A cross-over, randomised study was carried out on 40 individuals (11 males and 29 females) aged 21 to 30 years. The rate of reading and reading accuracy was calculated with and without ChromaGen blue filter lens in all subjects. Wilkins Rate of Reading Test was used to measure the rate of reading and reading accuracy. Contrast sensitivity was also evaluated by using with and without the ChromaGen blue filter lens.

    RESULTS: The mean rate of reading with and without ChromaGen blue filter lens was 160.58±16.03 words per minute and 150.52±15.66 words per minute respectively, with significant difference of p<0.001. The mean of reading accuracy (words correctly read per minute) in subjects, with ChromaGen blue filter was 149.30±0.79 words and without using filter lens was 148.53±1.11 words and found to be significant (p<0.001). There was no significant difference in the contrast sensitivity between subjects with and without the ChromaGen blue filter lens (p=0.083). No significant correlation was noted between the reading speed with age, spherical equivalent, contrast sensitivity, and reading accuracy.

    CONCLUSION: This study concludes that there was an increase of 6.68% in the rate of reading and improvement of 0.52% in accuracy among subjects with ChromaGen blue filter lens.

    Matched MeSH terms: Contrast Sensitivity*
  3. Chen AH, Mohamed D
    Clin Exp Ophthalmol, 2003 Oct;31(5):430-4.
    PMID: 14516432
    The Hiding Heidi low-contrast 'face' test is a new paediatric contrast test to evaluate the ability to detect objects with low contrast. The purpose of the present study was to compare the Hiding Heidi low-contrast 'face' test (HH) with the Pelli-Robson contrast sensitivity test (PR) and the functional acuity contrast test (FACT) in the low-contrast assessment.
    Matched MeSH terms: Contrast Sensitivity*
  4. Sharanjeet-Kaur, Kulikowski JJ, Carden D
    Ophthalmic Physiol Opt, 1998 Jan;18(1):49-56.
    PMID: 9666910
    The purpose of this study was to optimise the testing paradigm for isolating the contributions of chromatic and achromatic mechanisms to the human spectral sensitivity function. Spectral sensitivity was determined for a test spot size of 1.2 deg presented with various spatial and temporal masks on a large, 10 deg background field of moderate intensity (1000 td) and colour temperature, CT = 2700 K. Sinusoidal temporal presentation (1 Hz) and a masking annulus of between 3 and 10 min of arc surrounding the test spot, was found to be most effective in separating chromatic from achromatic mechanisms. Square-wave (1 Hz) temporal presentation combined with the annulus was slightly less selective. The presence of the annulus did not affect the shape of flicker detection at 25 Hz which is a measure of the luminosity (achromatic) spectral sensitivity function.
    Matched MeSH terms: Contrast Sensitivity
  5. Narayanasamy S, Vincent SJ, Sampson GP, Wood JM
    Clin Exp Optom, 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: Contrast Sensitivity
  6. Mohamad Fadzil N, Mohammed Z, Mohamad Shahimin M, Saliman NH
    PMID: 31783492 DOI: 10.3390/ijerph16234728
    This study aimed to assess the visual function, reading performance, and compensatory head posture (CHP) in schoolchildren with infantile nystagmus. A total of 18 participants aged between 13 to 18 years old were divided into spectacle (n = 9) and null zone group (n = 9) based on their visual acuity. Visual acuity (LogMAR), contrast sensitivity (Pelli-Robson), reading time and rate (Tobii TX300), and CHP were measured pre and post null zone reading training. Participants in the null zone group received 10 sessions of training (5 weeks). Visual acuity and contrast sensitivity of participants in the spectacle and null zone groups were not significantly different pre and post training. Reading performance, i.e., reading time (z = -1.36; p = 0.173) and reading rate (z = -0.06; p = 0.953), of participants in the spectacle group was not significantly different after 5 weeks. Reading time (z = -2.55; p = 0.011) and reading rate (z = -2.07; p = 0.038 of participants in the null zone group showed significant improvement post training. After 5 weeks, CHP improved in six out of the nine participants (66.7%) of the null zone group and was unchanged in all participants in the spectacle group. Null zone reading training could benefit children with infantile nystagmus in improving reading performance and compensatory head posture.
    Matched MeSH terms: Contrast Sensitivity
  7. Teoh SL, Allan D, Dutton GN, Foulds WS
    Br J Ophthalmol, 1990 Apr;74(4):215-9.
    PMID: 2186795
    The visual acuity, the difference in sensitivity of the two eyes to light (brightness ratio), and contrast sensitivity were assessed in 28 patients with chronic open angle glaucoma and compared with those of 41 normal controls of similar ages and visual acuity. The results obtained were related to the results of Tübingen visual field analysis in patients with glaucoma. Twenty-four of the 28 glaucoma patients (86%) had a significant disparity in brightness ratio between the two eyes. This was found to match the frequency of visual field loss. Moreover, there was a significant relationship between the interocular differences in brightness sense and the difference in the degree of visual field loss between the two eyes. Of the glaucoma patients 39% had sum contrast sensitivities outside the normal range for age-matched normal controls. No significant correlation was found between the interocular difference in brightness sense and the visual acuity or the interocular difference in sum contrast sensitivity. It is concluded that, in the presence of a normal visual acuity, the brightness ratio test warrants evaluation as a potential screening test for chronic open angle glaucoma.
    Matched MeSH terms: Contrast Sensitivity*
  8. Hilmi MR, Che Azemin MZ, Mohd Kamal K, Mohd Tamrin MI, Abdul Gaffur N, Tengku Sembok TM
    Curr Eye Res, 2017 Jun;42(6):852-856.
    PMID: 28118054 DOI: 10.1080/02713683.2016.1250277
    PURPOSE: The goal of this study was to predict visual acuity (VA) and contrast sensitivity function (CSF) with tissue redness grading after pterygium surgery.

    MATERIALS AND METHODS: A total of 67 primary pterygium participants were selected from patients who visited an ophthalmology clinic. We developed a semi-automated computer program to measure the pterygium fibrovascular redness from digital pterygium images. The final outcome of this software is a continuous scale grading of 1 (minimum redness) to 3 (maximum redness). The region of interest (ROI) was selected manually using the software. Reliability was determined by repeat grading of all 67 images, and its association with CSF and VA was examined.

    RESULTS: The mean and standard deviation of redness of the pterygium fibrovascular images was 1.88 ± 0.55. Intra-grader and inter-grader reliability estimates were high with intraclass correlation ranging from 0.97 to 0.98. The new grading was positively associated with CSF (p < 0.01) and VA (p < 0.01). The redness grading was able to predict 25% and 23% of the variance in the CSF and the VA, respectively.

    CONCLUSIONS: The new grading of pterygium fibrovascular redness can be reliably measured from digital images and showed a good correlation with CSF and VA. The redness grading can be used in addition to the existing pterygium grading.
    Matched MeSH terms: Contrast Sensitivity*
  9. Ong Chin Feng W, Wan Hitam WH
    Taiwan J Ophthalmol, 2020 06 20;10(3):189-196.
    PMID: 33110750 DOI: 10.4103/tjo.tjo_22_20
    Purpose: Peripapillary retinal nerve fibre layer (RNFL) thickness might be useful in monitoring ongoing subclinical structural damage especially in eyes with no history of optic neuritis (ON) in neuromyelitis optica (NMO).

    Objective: To evaluate the peripapillary RNFL thickness and optic nerve functions in fellow eye of NMO with unilateral optic neuritis.

    Materials and Methods: A comparative cross-sectional study was conducted in 2 tertiary hospitals from August 2017 to May 2019. RNFL thickness and optic nerve functions were evaluated. Statistical analysis was performed using Statistical Package for Social Science version 24.

    Results: A total of 26 NMO patients and 26 controls were involved in this study. The median age (IQR) of NMO patients was 32.5 (12) years old. The RNFL thickness was significantly reduced in NMO patients with non-ON eyes as compared to control group. Best corrected visual acuity between the 2 groups were comparable (0.20 vs 0.00, p=0.071). Contrast sensitivity was also reduced in NMO patients (non-ON eyes) at all 5 spatial frequencies. In NMO group, 34.6% have normal colour vision. The mean deviation (MD) of Humphrey visual field (HVF) was higher in NMO group (p<0.001). There was a moderate correlation between RNFL thickness and contrast sensitivity. Weak correlation was found between the RNFL thickness with visual acuity and mean deviation of visual field test.

    Conclusion: Our study showed that the fellow eye of NMO patients with unilateral ON revealed a significant reduction in RNFL thickness and all the optic nerve functions have subtle early changes that signify a subclinical retinal damage.

    Matched MeSH terms: Contrast Sensitivity
  10. Amir NN, Kamaruzzaman SB, Effendi-Tenang I, Jamaluddin M, Tan MP, Ramli N, et al.
    Eur Geriatr Med, 2021 Apr;12(2):313-319.
    PMID: 33486745 DOI: 10.1007/s41999-021-00450-2
    PURPOSE: Using data from the Malaysian Elders Longitudinal Research (MELoR), this study investigated the association between visual function (visual acuity and contrast sensitivity) and frailty in a group of urban-dwelling older adults.

    METHODS: This was a cross-sectional study. 1332 participants aged ≥ 55 years were selected by random sampling from the parliamentary electoral register. Only 1274 participants completed the frailty assessment and 1278 participants completed the contrast sensitivity assessment. Impaired vision was defined as a Snellen visual acuity of worse than 6/12 in the better eye. Poor contrast sensitivity was defined as a score on the Pelli Robson chart of lower than 1.65. Frailty was defined with the Fried's phenotype criteria. Inter-group comparisons were determined with the independent T-test for continuous variables and the Pearson's Chi-squared test for categorical variables. The odds ratio (OR) with 95% confidence interval (CI) was used to evaluate the cross-sectional association between frailty and visual function.

    RESULTS: The mean age of participants was 68.8 ± 7.5 years, of which 58.1% (774) were women. Impaired vision and poor contrast sensitivity were present in 187 (14%) and 271 (21.2%) subjects respectively. 73 (5.8%) individuals were classified as frail, 1161 (91.0.%) pre-frail, and 40 (2.8%) non-frail. There was no significant difference in frailty phenotypes between those with good and impaired vision (p = 0.241). Fried's component of handgrip strength, gait speed and exhaustion were significantly better in those with good visual function (p contrast sensitivity were significantly more likely to be frail (OR: 5.34, p = 0.004).

    CONCLUSION: Poor contrast sensitivity was significantly associated with frailty. This highlights the importance of incorporating assessment of contrast sensitivity in those at risk of frailty.

    Matched MeSH terms: Contrast Sensitivity
  11. Matthew TJH, Tharakan J, Tai E, Hussein A
    Cureus, 2019 Apr 27;11(4):e4553.
    PMID: 31275777 DOI: 10.7759/cureus.4553
    Objective Epilepsy is a debilitating disease. Visual function changes have been reported and may be attributed to the epileptic changes or as a result of medication side effect. Sodium valproate and carbamazepine are both first line anti-epileptic medications used in Malaysian health care. Sodium valproate inhibits glutamate and γ-aminobutyric acid (GABA) transaminase while carbamazepine acts on the sodium channel - both are an important part of the retina. This study aimed to compare the visual functions of epilepsy patients on carbamazepine or sodium valproate monotherapy. Design A cross-sectional study was conducted at a tertiary hospital between June 2016 and November 2018. Methods Patients with idiopathic epilepsy that fulfill the inclusion and exclusion criteria were recruited from the neurology clinic. They were divided into two groups and underwent complete eye examinations. Visual functions such as color vision testing, contrast sensitivity, visual field and retinal nerve fiber layer measurement were subsequently performed. Statistical analysis was done using Statistical Package for the Social Science, version 24 (SPSS Inc, Chicago, IL, USA). Results A total of 100 patients (sodium valproate: 50 patients; carbamazepine: 50 patients) were recruited for the study. There were no statistically significant changes in anatomical or visual function between the sodium valproate and carbamazepine group. However, patients from both groups displayed color vision defect in the blue and green axes. Changes in color vision could indicate early retina toxicity secondary to the medication. Although there were no visual field changes, patients recorded a slight reduction of mean deviation. Changes of mean deviation could be attributed to the side effect of medication or the disease process. Conclusions Epileptic patients taking sodium valproate or carbamazepine did not demonstrate statistically significant change in visual function.
    Matched MeSH terms: Contrast Sensitivity
Filters
Contact Us

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links