Functional MRI characteristics in visual cortex (BA 17, 18 and 19) corresponding to the visual field of normal, glaucoma suspect (GS) and primary open angle glaucoma (POAG) patients

The purpose of this study was to characterize, differentiate and correlate visual field and brain activation in visual cortex for normal, glaucoma suspect (GS) and primary open angle glaucoma (POAG) participants using Standard Automated Perimetry (SAP) and functional Magnetic Resonance Imaging (fMRI) respectively. The fMRI scans and SAP test were both carried out in Pusat Perubatan Universiti Kebangsaan Malaysia (PPUKM). Two types of black-and-white checkerboard pattern were displayed to the participants during the fMRI scans. The fMRI data were analyzed using WFU pickatlas toolbox targeting visual cortex area. The results showed that there was no significant difference in number of activated voxel between the three groups in visual cortex (BA 17, 18 and 19) while viewing all the given stimuli (p > 0.05). The pattern standard deviation (PSD) of SAP for visual field also revealed no significant differences (p > 0.05) in all groups of participants. However, negative correlation between PSD and fMRI activation was observed. The PSD values increased with a decrease in fMRI activation. With reference to visual field analysis, the results suggest that glaucomatous neuropathy of POAG patients has led to a gradual decrease in visual cortex activation and a gradual increase in PSD

Signal change in BA17, 18 and 19: A comparative study of normal, glaucoma suspects and POAGpatients

Magnetic resonance signal change is expected to be different between normal, glaucoma suspect (GS) and Primary Open Angle Glaucoma (POAG) subjects. Functional magnetic resonance imaging (fMRI) technique was employed to investigate the differences. This multiple subject studies were carried out to characterize the percentage of signal change (PSC) in Brodmann Area (BA) 17, 18 and 19 of the visual cortex. The block designed fMRI was implemented. The subjects were requested to focus on the black and white checkerboard stimulus of the visual world (A, B and CD), visual field (EF) and visual area (G). The data were analysed using Statistical Parametric Mapping (SPM8) via Matlab platform. results showed that GS subjects have the highest PSC, followed by normal and POAG subjects. However, no significant difference was observed in PSC between BA17, 18 and 19 for normal, GS and POAG groups with p = 0.0869, p = 0.0688 and p = 0.2690, respectively. In conclusion, none of the BA can be suggested to be the most dominant area in responding to the visual stimuli used in this study

Relationship between refractive error, axial length and macula thickness in Malay subjects / Noor Hidayah Mohamad … [et al.]

Background: In myopic eyes, the axial length of the globe exceeds normal dimensions, and the sclera becomes thinner, especially at the posterior pole. Therefore, the retina at the posterior pole may stretch in myopic eyes. Thus, it has been hypothesized that highly myopic eyes have thinner retinas as compared with emmetropic eyes. Problem statement: It is still controversial on the results of the correlation between the axial length, the retinal thickness and refractive error in healthy eyes. It may be because of the ocular dimensions are varies according to race. There is no study has been done to measure the correlation between the axial length, retinal thickness and refractive error among the Malay population. Objective: This research will be done to measure the correlation between the axial length, retinal thickness and refractive error of the healthy eyes among Malay students in UiTM. Methodology: A cross-sectional study will be conducted at Optometry Clinic, FSK, UiTM, which 45 UiTM students will be screened with history taking and preliminary tests to be a subject. The preliminary tests include visual acuity measurement using Snellen chart, Hirschberg test using pen torch, fundus examination using direct ophthalmoscope and anterior segment examination using slit lamp. The refractive error of the subject then will be objectively examined by autorefractor and will be refined subjectively. The retinal thickness will be measured using Optical Coherence Tomography (OCT) and the axial length will be measured using B-scan. Data will be analyzed using SPSS programme. Hypothesis: There are correlation between the axial length, retinal thickness and refractive error of healthy eyes among Malay students in UiTM. Outcomes: If this hypothesis is proven, these parameters should always be considered when assessing axial length progression, or retinal thickening, or refractive error progression among Malay population in future study

Perbandingan zon interaksi ruang dua dimensi subjek normal dan ambliopia anisometropik

Akuiti visual subjek ambliopia anisometropik sering disimulasi pada individu normal dengan mengkaburkan penglihatan fovea mereka. Walau bagaimanapun, prestasi akuiti visual periferi subjek ini tidak diketahui dan kaedah pengkaburan ini tidak semestinya dapat mensimulasi penglihatan periferi mereka. Untuk mendalami ketepatan kaedah ini, kami mengkaji akuiti dan bentuk zon interaksi ruang di fovea dan periferi retina subjek normal dan ambliopia anisometropik serta kesan pengkaburan pada akuiti subjek normal pada esentrisiti retina yang berbeza untuk dibandingkan dengan periferi subjek ambliopia. Akuiti diukur menggunakan Kaedah Rangsangan Malar untuk huruf Sheridan-Gardiner pada 6 orang subjek normal dan 6 orang subjek ambliopia anisometropik. Kesan kesesakan diukur dengan membandingkan respons pengesanan huruf sasaran yang diapit oleh huruf lain yang diletakkan pada orientasi mendatar, menegak dan pepenjuru. Rangsangan dipaparkan pada fovea dan 2.5, 5 dan 10 darjah di medan penglihatan inferior. Selain itu, akuiti fovea 4 orang subjek normal dikaburkan supaya sepadan dengan akuiti fovea subjek ambliopia menggunakan kaedah pengkaburan optik dan penuras digital Gaussian. Subjek normal menunjukkan kemerosotan akuiti yang lebih besar dengan peningkatan esentrisiti retina (E2: 2.25±0.21) berbanding subjek ambliopia anisometropik (E2: 6.02±1.45). Kesemua subjek menunjukkan zon interaksi ruang yang tidak simetri di kesemua esentrisiti retina yang diuji. Interaksi antara jenis kabur dan esentrisiti retina adalah signifikan F(2.13,6.38)=4.93, p=0.049) tetapi akuiti subjek normal yang dikaburkan dengan kedua-dua kaedah pengkaburan tidak berbeza secara signifikan dengan akuiti subjek ambliopia. Zon interaksi ruang subjek ambliopia anisometropik adalah sama dengan subjek normal. Akuiti fovea subjek ambliopia anisometropik lebih teruk berbanding subjek normal kerana peningkatan pengkaburan intrinsik. Walau bagaimanapun, periferi subjek ambliopia adalah normal secara fungsian

Comparison of habitual visual acuity and stereoacuity between children attending KEMAS and urban private preschools

The assessment of a preschooler’s visual status is important as it forms part of the measure to assess the child’s school readiness. However, not all children attending preschools have equal opportunity to undergo vision screening programmes. In this study, we measured presenting habitual near and distance visual acuity and stereoacuity in 6-year-old children (n=385). These parameters were measured in and compared between preschoolers attending urban, privately-run kindergartens and those attending KEMAS preschools, which were typically from suburban and rural areas with families of very low income. Seven percent of KEMAS preschoolers failed the distance visual acuity test while the failure rate for private preschoolers was 6.0%. For near visual acuity, a higher percentage of private preschoolers failed the test (8.7%) than KEMAS preschoolers (4.9%). A slightly higher percentage of private preschoolers had weak stereopsis (3.3%) compared to KEMAS preschoolers (2.5%). However, the differences found between the two preschooler groups were not statistically significant (all p>0.05). The proportion of children who failed each of the screening criteria for distance vision, near vision, and stereopsis was similar between KEMAS and private preschools. Therefore, an universally inclusive vision screening programme should be conducted for all preschool types to detect, diagnose, treat, and potentially prevent any visual impairment

Behavioural and emotional issues among primary school pupils with congenital colour vision deficiency in the Federal Territory of Kuala Lumpur, Malaysia: A case-control study [version 1; referees: 2 approved, 1 approved with reservations]

Background: Congenital colour vision deficiency (CCVD) is an untreatable disorder which has lifelong consequences. Increasing use of colours in schools has raised concern for pupils with CCVD. This case-control study was conducted to compare behavioural and emotional issues among age, gender and class-matched pupils with CCVD and normal colour vision (NCV). Methods: A total of 1732 pupils from 10 primary schools in the Federal Territory of Kuala Lumpur were screened, of which 46 pupils (45 males and 1 female) had CCVD. Mothers of male pupils with CCVD (n=44) and NCV (n=44) who gave consent were recruited to complete a self-administered parent report form, Child Behaviour Checklist for Ages 4-18 (CBCL/ 4-18) used to access behavioural and emotional problems. The CBCL/ 4-18 has three broad groupings: Internalising, Externalising and Total Behaviour Problems. Internalising Problems combines the Withdrawn, Somatic Complaints and Anxiety/ Depression sub constructs, while Externalising Problems combines the Delinquent and Aggressive Behaviour sub constructs. Results: Results from CBCL/ 4-18 showed that all pupils from both groups had scores within the normal range for all constructs. However, results from the statistical analysis for comparison, Mann-Whitney U test, showed that pupils with CCVD scored significantly higher for Externalising Problems (U=697.50, p=0.02) and Total Behaviour Problems (U=647.00, p= 0.01). Significantly higher scores were observed in Withdrawn (U=714.00, p=0.02), Thought Problems (U=438.50, p<0.001) and Aggressive Behaviour (U=738.00, p=0.04). Odds ratios, 95% CI, showed significant relative risk for high Total Behaviour Problem (OR:2.39 ,CI:1.0-5.7), Externalising Problems (OR:2.32, CI:1.0-5.5), Withdrawn (OR:2.67, CI:1.1-6.5), Thought Problems (OR:9.64, CI:3.6-26.1) and Aggressive Behaviour (OR:10.26, CI:3.4-31.0) scores among pupils with CCVD. Conclusion: Higher scores among CCVD pupils indicates that they present more behavioural and emotional problems compared to NCV pupils. Therefore, school vision screenings in Malaysia should also include colour vision to assist in the early clinical management of CCVD children

A Component of Retinal Light Adaptation Mediated by the Thyroid Hormone Cascade

Analysis with DNA-microrrays and real time PCR show that several genes involved in the thyroid hormone cascade, such as deiodinase 2 and 3 (Dio2 and Dio3) are differentially regulated by the circadian clock and by changes of the ambient light. The expression level of Dio2 in adult rats (2–3 months of age) kept continuously in darkness is modulated by the circadian clock and is up-regulated by 2 fold at midday. When the diurnal ambient light was on, the expression level of Dio2 increased by 4–8 fold and a consequent increase of the related protein was detected around the nuclei of retinal photoreceptors and of neurons in inner and outer nuclear layers. The expression level of Dio3 had a different temporal pattern and was down-regulated by diurnal light. Our results suggest that DIO2 and DIO3 have a role not only in the developing retina but also in the adult retina and are powerfully regulated by light. As the thyroid hormone is a ligand-inducible transcription factor controlling the expression of several target genes, the transcriptional activation of Dio2 could be a novel genomic component of light adaptation

Blue deficiency in patients with diabetis mellitus without retinopathy - its clincial implications

This study was conducted for 3 main purposes: 1) to determine if there was blue colour deficiency amongst diabetes mellitus (IDDM and NIDDM) patients without retinopathy, 2) to determine if the Dl5 test could be used to detect any colour vision defects amongst diabetics without retinopathy (all previous workers have used FM 100-Hue), and 3) to assess the performance of diabetics without retinopathy in detecting correct colour changes with the urine strip test. Thirty eight non-insulin dependent diabetes mellitus (NIDDM) and 30 insulin-dependent diabetes mellitus (IDDM) patients without retinopathy participated in this study. A control group of 23 normal subjects were also included in the study. Dl5 colour vision test was performed under daylight conditions. Colour dependent urine glucose test (Glukotest) was also performed on all subjects. The study showed that 47.1% of diabetics (47.4% NIDDM and 46.7% IDDM patients) without retinopathy had a blue colour deficiency. Amongst the diabetics with a blue colour deficiency, 25% of diabetics (22% of NIDDM and 28.6% of IDDM patients) failed to accurately match the strip colour with the comparison chart on the bottle