Various Ways of Continuous Intraocular Pressure Monitoring in Glaucoma Patients: A Narrative Review

@#Glaukoma adalah sejenis penyakit neurodegeneratif yang berlaku akibat ketidakseimbangan dalam peredaran cecair akues yang disebabkan oleh resistan pada sistem pengaliran keluar cecair tersebut. Ini meningkatkan tekanan intraokular (TIO) yang menyebabkan kerosakan pada saraf optik dan seterusnya mengakibatkan kebutaan yang kekal. Oleh kerana TIO adalah satu faktor risiko glaukoma yang boleh dikawal, ciri-ciri dan variasi tekanan sepanjang 24 jam perlu dikenalpasti sebelum rawatan dimulakan. Pemantauan TIO adalah satu aspek yang terpenting dan kritikal dalam pengurusan glaukoma. Pelbagai tindakan kawalan melalui penggunaan teknologi yang berbeza telah dan sedang dilakukan untuk pemantauan TIO yang kerap dan berterusan selama 24 jam untuk menentukan kewujudan TIO yang tinggi (peak) dan fluktuasi tekanan. Artikel ini bertujuan untuk meninjau pendekatan inovatif yang terkini serta untuk mengulas kepentingan dan kelemahan setiap teknik bagi memperolehi profil TIO selama 24 jam.

Visual Functions And Retinal Morphology In Patients With Polypoidal Choroidal Vasculopathy Seen In An Age Related Macular Degeneration Referral Centre Of Malaysia

@#The aim of the present study was to evaluate visual functions and retinal morphology of Polypoidal Choroidal Vasculopathy (PCV) patients seen in an AMD referral centre of Malaysia and to further explore association between visual functions and optical coherence tomography (OCT) parameters in PCV eyes. In this single centre, cross sectional study, best corrected distance visual acuity (DVA), near vision acuity (NVA), reading speed (RS), and contrast sensitivity (CS) were measured in naïve PCV eyes. Selective parameters such as integrity of external limiting membrane (ELM), inner segment and outer segment junction (IS-OS), retinal pigment epithelium and Bruch’s membrane (RPE-BM) complex, average retinal thickness (ART) and volume (ARV), central retinal thickness (CT), centre maximum (CTmax) and centre minimum (CTmin) thickness were assessed using spectral-domain OCT. Forty-three new PCV eyes of 42 patients were evaluated. Mean (±SD) DVA, NVA, CS, RS were 0.83 ± 0.35 logMAR, 0.77 ± 0.3 logMAR, 0.69 ±.26 log CS and 59.56 ±14 words per minutes respectively. ART and CT showed good correlation with DVA (r=0.571& 0.546) and CS (r= 0.576 & 0.586). ARV and CTmax showed good correlation with CS (r=0.516 &, 0.513). The mean DVA, NVA and CS between three ELM and IS-OS status were significantly different (p=.002 & .000; p=.012 & .029; p=.005 & .001). In conclusion, present study reports visual functions and OCT characteristics of PCV patients in an AMD referral centre of Malaysia. Many of the quantitative and qualitative OCT parameters showed good association with the visual functions in eyes with PCV.

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 / Jurnal Sains Kesihatan Malaysia

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.

Corneal Cell Morphology in Keratoconus: A Confocal Microscopic Observation

Purpose: To evaluate corneal cell morphology in patients with keratoconus using an in vivo slit scanning confocal microscope. Methods: A cross-sectional study was conducted to evaluate the corneal cell morphology of 47 keratoconus patients and 32 healthy eyes without any ocular disease. New keratoconus patients with different disease severities and without any other ocular co-morbidity were recruited from the ophthalmology department of a public hospital in Malaysia from June 2013 to May 2014. Corneal cell morphology was evaluated using an in vivo slit-scanning confocal microscope. Qualitative and quantitative data were analysed using a grading scale and the Nidek Advanced Visual Information System software, respectively. Results: The corneal cell morphology of patients with keratoconus was significantly different from that of healthy eyes except in endothelial cell density (P = 0.072). In the keratoconus group, increased level of stromal haze, alterations such as the elongation of keratocyte nuclei and clustering of cells at the anterior stroma, and dark bands in the posterior stroma were observed with increased severity of the disease. The mean anterior and posterior stromal keratocyte densities and cell areas among the different stages of keratoconus were significantly different (P 0.05) among the three stages of keratoconus. Conclusion: Confocal microscopy observation showed significant changes in corneal cell morphology in keratoconic cornea from normal healthy cornea. Analysis also showed significant changes in different severities of keratoconus. Understanding the corneal cell morphology changes in keratoconus may help in the long-term monitoring and management of keratoconus.

A Comparative Study on the Inter-Session and InterExaminer Reliability of Corneal Power Measurement Using Various Keratometry Instruments

The purpose of this study was to evaluate inter-session repeatability, inter-examiner reproducibility and inter-device agreement of corneal power measurements from manual keratometer, autokeratometer, topographer, Pentacam high resolution and IOLMaster. Methods: Two sets of mean corneal power measurements (n=40) were compared for inter-session repeatability and inter-examiner reproducibility in each instrument. Repeatability and reproducibility were evaluated by within-subject standard deviation (Sw), coefficient of variation (COV) and intraclass correlation coefficient (ICC). A oneway repeated measures analysis of variance was conducted to compare differences in the corneal power between each instrument pair. The Bland and Altman analysis and Pearson’s correlation were employed to assess agreement and determine strength of relationship between measurements. Results: There were no significant differences in mean corneal power measurements between 2 different visits (p > 0.05). The Sw and COV values between 2 visits were lower than 0.09 D and 0.20 % respectively. The ICCs were stronger than 0.99 in all instruments. For reproducibility of each instrument, differences of the measurements between 2 different examiners were also insignificant (p > 0.05). The Sw and COV values between 2 examiners were lower than 0.11 D and 0.23 % respectively. The ICCs were 0.99 and above in all instruments. The 95% limit of agreement between instruments ranged from -0.29 to 1.13 D and the r-values were stronger than 0.84. Conclusion: The corneal power measurements using these 5 instruments were repeatable and reproducible. These instruments can also be used interchangeably, however the topographer should be used with caution.

Brain Activation Due to Various Visual Stimuli: A Pilot Study using Fixed-effects Analysis on Healthy Participants / Jurnal Sains Kesihatan Malaysia

Ocular abnormalities have apparent effects on brain activation. However, neuroimaging data about the ocular characteristics of healthy participants are still lacking to be compared with data for patients with ocular pathology. The objective of this multiple participants’ functional magnetic resonance imaging (fMRI) studies was to investigate the brain activation characteristics of healthy participants when they view stimuli of various shapes, pattern and size. During the fMRI scans, the participants view the growing ring, rotating wedge, fl ipping hour glass/bow tie, quadrant arc and full checker board stimuli. All stimuli have elements of black-and-white checkerboard pattern. Statistical parametric mapping (SPM) was used in generating brain activation via fi xed-effects (FFX) and conjunction analyses. The stimuli of various shapes, pattern and size produce different brain activation with more activation concentrated in the left hemisphere. These results are supported by the conjunction analysis which indicated that the left pre-central, post-central, superior temporal and occipital gyrus as well as the left cingulate cortices were involved when the participants viewed each given stimulus. Differential activation analysis showed activation with high specifi city in the occipital region due to the stimuli of various shapes, pattern and size. The activation in the right middle temporal gyrus was found to be signifi cantly higher in response to moving stimuli as compared to stationary stimuli. This confi rms the involvement of the right middle temporal gyrus in the observation of movements. The black-and-white checkerboard stimuli of various shapes, pattern and size, stationary and moving was found to 1) activate visual as well as other cortices in temporal and parietal lobes, 2) cause asymmetry in brain function and 3) exhibit functional integration characteristics in several brain areas.

Heredity factor in myopia development among a sample in Klang Valley, Malaysia / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Development of myopia among young children is often contributed to the refractive status of the parents. This study was conducted to determine whether myopia can be inherited across the generation among a sample in the Klang Valley. Three generations involved are: G1 (grandparents), G2 (parents) and G3 (children).</p><p><b>METHODS</b>Sixty-two families were screened and forty families were selected to participate in this study. The inclusion criterion is having at least one myopic member in any of the three generations. Subjects (G2) were first asked to fill up a questionnaire form before their refractive status was determined by clinical examination that provided acuity of 6/6 or better. Refractive status of G1 was determined using information from the questionnaire while for G2 and G3 through clinical examination.</p><p><b>RESULTS</b>Generally, the prevalence of myopia is seen to increase throughout the generations from G1 being the lowest (25.6%) to G3 being the highest (41.1%). Strong genetic influence can be found between G1 and G2 as majority of myopes in G2 is when both parents were myopic. However, although the prevalence of myopia increased from G2 to G3, there was no strong genetical influence. Majority of subjects in G3 were non-myopes when both their parents were myopic.</p><p><b>CONCLUSION</b>Parental history accounts for a limited proportion of variance in myopia development.</p>

The Changes of Tear Status after Conventional and Wavefront-Guided IntraLASIK

Background: IntraLASIK is a LASIK surgery that involved IntraLase femtosecond laser for the corneal flap creating. The objective of this research was to investigate and compare the changes in tear status at 1 and 3 months after undergoing conventional IntraLASIK with Bausch & Lomb PlanoScan (PS) algorithm, Bausch & Lomb Zyoptix Tissue Saving (ZTS) algorithm, and wavefrontguided (WG) IntraLASIK with VISX CustomVue. Methods: Tear status of 36 patients who were divided into 3 groups depending on the type of IntraLASIK they underwent (PS, n = 13; ZTS, n = 9; WG, n = 14) was evaluated. Tear status was determined by classifying the category of the thickness of pre-corneal tear lipid layer, non-invasive tear break-up time, and tear meniscus height. Repeated measures analysis of variance (ANOVA) and one way ANOVA were used for the statistical analyses. Results: The category of the thickness of tear lipid layer, non-invasive tear break up time and tear meniscus height were neither significantly changed after IntraLASIK for all groups nor showed significant difference among groups at 1 and 3 months post-IntraLASIK (P > 0.05). Blinking rate and palpebral aperture also had no significant changed after IntraLASIK. Conclusion: Both conventional (PS and ZTS) and WG IntraLASIK did not affect tear status up to 3 months post-IntraLASIK. WG IntraLASIK did not show superiority in preserving tear status 1 and 3 months post-surgery compared with conventional IntraLASIK.