Displaying publications 1 - 20 of 29 in total

  1. Zouache MA, Eames I, Samsudin A
    PLoS One, 2016;11(3):e0151490.
    PMID: 26990431 DOI: 10.1371/journal.pone.0151490
    In vertebrates, intraocular pressure (IOP) is required to maintain the eye into a shape allowing it to function as an optical instrument. It is sustained by the balance between the production of aqueous humour by the ciliary body and the resistance to its outflow from the eye. Dysregulation of the IOP is often pathological to vision. High IOP may lead to glaucoma, which is in man the second most prevalent cause of blindness. Here, we examine the importance of the IOP and rate of formation of aqueous humour in the development of vertebrate eyes by performing allometric and scaling analyses of the forces acting on the eye during head movement and the energy demands of the cornea, and testing the predictions of the models against a list of measurements in vertebrates collated through a systematic review. We show that the IOP has a weak dependence on body mass, and that in order to maintain the focal length of the eye, it needs to be an order of magnitude greater than the pressure drop across the eye resulting from gravity or head movement. This constitutes an evolutionary constraint that is common to all vertebrates. In animals with cornea-based optics, this constraint also represents a condition to maintain visual acuity. Estimated IOPs were found to increase with the evolution of terrestrial animals. The rate of formation of aqueous humour was found to be adjusted to the metabolic requirements of the cornea, scaling as Vac(0.67), where Vac is the volume of the anterior chamber. The present work highlights an interdependence between IOP and aqueous flow rate crucial to ocular function that must be considered to understand the evolution of the dioptric apparatus. It should also be taken into consideration in the prevention and treatment of glaucoma.
    Matched MeSH terms: Intraocular Pressure/physiology*
  2. Mohan SM, Reddy SC, Wei LY
    Int Ophthalmol, 2001;24(6):305-11.
    PMID: 14750567
    PURPOSE: To determine the effects of unilateral right/left nostril breathing (URNB/ULNB) and forced unilateral right/left nostril breathing (FURNB/FULNB) on intraocular pressure (IOP) and to examine the differences in the IOP during the various phases of nasal cycle.

    METHODS: Young healthy volunteers of either sex aged between 19-24 years, participated in the sessions using URNB/ULNB (n = 52) and FURNB/FULNB (n = 28). The nostril dominance was calculated from signals recorded on the PowerLab equipment, representing pressure changes at the end of the nostrils during respiration. The IOP was measured with Tono-Pen. The subjects were divided into 4 groups viz. right nostril dominant (RND), left nostril dominant (LND), transitional right nostril dominant (TRND) and transitional left nostril dominant (TLND) groups. The IOP data 'before and after' URNB/ULNB or FURNB/FULNB were compared by using paired t-test. The baseline data of IOP between the groups were analysed by using independent samples t-test.

    RESULTS: The URNB decreased the IOP in the LND and TLND (p < 0.01) and also in the RND (p < 0.05) groups but not significantly in the TRND group. The ULNB decreased the IOP in the RND group (p < 0.01) only. The FURNB significantly reduced the IOP (p < 0.05) only in the LND and RND groups. The FULNB decreased the IOP but not significantly. The baseline IOP did not differ significantly between the LND, RND, TLND and TRND groups.

    CONCLUSION: The URNB/FURNB reduced the IOP, while ULNB/FULNB failed to increase the IOP significantly. It is suggested that the lowering of IOP by URNB indicated sympathetic stimulation.

    Matched MeSH terms: Intraocular Pressure/physiology*
  3. Samsudin A, Mimiwati Z, Soong T, Fauzi MS, Zabri K
    Eye (Lond), 2010 Jan;24(1):70-3.
    PMID: 19229270 DOI: 10.1038/eye.2009.33
    To study the effect of haemodialysis on intraocular pressure (IOP) of patients at the University Malaya Medical Centre, Kuala Lumpur, and the influence of anterior chamber angles, surgery, and diabetes on the change in IOP after haemodialysis.
    Matched MeSH terms: Intraocular Pressure/physiology*
  4. Singh M, Kaur B
    Int Ophthalmol, 1992 May;16(3):163-6.
    PMID: 1452420
    Postural behaviour of intraocular pressure (IOP) was studied in 29 glaucomatous eyes before and after argon laser trabeculoplasty (ALT) and compared with that of 60 normal eyes. Although argon laser trabeculoplasty was successful in lowering the IOP below 21 mm Hg, it produced little effect on the postural behaviour of the IOP. No significant change was observed in the amplitude of postural rise of IOP in ALT treated eyes.
    Matched MeSH terms: Intraocular Pressure/physiology*
  5. Marcus AJ, Iezhitsa I, Agarwal R, Vassiliev P, Spasov A, Zhukovskaya O, et al.
    Eur J Pharm Sci, 2018 Mar 01;114:245-254.
    PMID: 29274441 DOI: 10.1016/j.ejps.2017.12.015
    In an effort to find new ocular hypotensive drug candidates, a total of 27 condensed benzimidazoles based compounds were screened. This study was done in normotensive rats and rebound tonometry was used to estimate IOP. All compounds were topically applied as a single drop, unilaterally, at 3 different concentrations (0.1%, 0.2% and 0.4%). The contralateral eye was instilled with vehicle and served as control. The IOP reduction was measured up to 6h. It was observed that with a single topical instillation, compounds RU 551, RU 555, RU839 (pyrimido[1,2-a]benzimidazole derivatives), and RU 615 (imidazo[1,2-a]benzimidazole derivative) showed significant IOP lowering activities in ocular normotensive rats. All other compounds showed none, weak and inconsistent IOP lowering effect. The relationship between ability of IOP lowering and hypotensive activities was studied. According to the pharmacophore analysis, the class of pyrimido[1,2-a]benzimidazole is more promising than the class of imidazo[1,2-a]benzimidazole as a source of compounds with high IOP lowering activity. Pharmacophore analysis also showed that the critical features of high IOP lowering activity are methoxyphenyl and [phenyl]alkyl fragments, and non-conjugated six-membered heterocyclic ring.
    Matched MeSH terms: Intraocular Pressure/physiology
  6. Choo MM, Yeong CM, Grigg JR, Khaliddin N, Kadir AJ, Barnes EH, et al.
    Medicine (Baltimore), 2018 Nov;97(48):e13357.
    PMID: 30508927 DOI: 10.1097/MD.0000000000013357
    To report observations of horizontal corneal diameter (HCD) and central corneal thickness (CCT) changes in premature infants with stable optic disc cupping and intraocular pressures (IOPs). The HCD and CCT at term serve as a baseline for premature infants.Sixty-three premature infants were enrolled in a prospective case series. HCD, CCT, and IOP were measured. RetCam images of the optic discs were used to evaluate the cup-disc ratio (CDR) and read by an independent masked observer. Data were collected at between preterm (32-36 weeks) and again at term (37-41 weeks) postconceptual age. Left eye measurements were used for statistical analysis. Left eye findings were combined to construct predictive models for HCD and CCT.The mean HCD was 9.1 mm (standard deviation [SD] = 0.7 mm) at preterm and 10.0 mm (SD = 0.52 mm) at term. The mean CCT preterm was 618.8 (SD = 72.9) μm and at term 563.9 (SD = 50.7) μm, respectively. The average preterm CDR was 0.31 and at maturity was 0.33. Average IOP of preterm and term was 13.1 and 14.11 mm Hg, respectively. There was significant linear correlation between HCD with the postmenstrual age (r = 0.40, P 
    Matched MeSH terms: Intraocular Pressure/physiology*
  7. Samsudin A, Eames I, Brocchini S, Khaw PT
    J Glaucoma, 2016 Jan;25(1):e39-45.
    PMID: 25719236 DOI: 10.1097/IJG.0000000000000243
    PURPOSE: ExPress devices are available as P50 and P200 models, the numbers related to their luminal diameters in μm. We compared their Poiseuille's Law-based theoretical resistance values with experimental values and correlated these with their luminal dimensions derived from electron microscopy.

    METHODS: Scanning electron microscopy was performed on P50 and P200 devices. Bench-top flow studies were performed to find the resistances of the devices. Devices were also incorporated into a perfused, ex vivo porcine sclera model to test and compare their control of pressure, with and without overlying scleral flaps, and with trabeculectomies.

    RESULTS: The luminal dimensions of the P200 device were 206.4±3.3 and 204.5±0.9 μm at the subconjunctival space and anterior chamber ends, respectively. Those of the P50 device were 205.0±5.8 and 206.9±3.7 μm, respectively. There were no significant differences between the P200 and P50 devices (all P>0.05). The resistances of the P200 and P50 devices were 0.010±0.001 and 0.054±0.002 mm Hg/μL/min, respectively (P<0.05). Equilibrium pressures with overlying scleral flaps were 17.81±3.30 mm Hg for the P50, 17.31±4.24 mm Hg for the P200, and 16.28±6.67 mm Hg for trabeculectomies (P=0.850).

    CONCLUSIONS: The luminal diameters of both devices are externally similar. The effective luminal diameter of the P50 is much larger than 50 μm. Both devices have low resistance values, making them unlikely to prevent hypotony on their own. They lead to similar equilibrium pressures as the trabeculectomy procedure when inserted under the scleral flap.

    Matched MeSH terms: Intraocular Pressure/physiology
  8. Chong KL, Samsudin A, Keng TC, Kamalden TA, Ramli N
    J Glaucoma, 2017 Feb;26(2):e37-e40.
    PMID: 27599172 DOI: 10.1097/IJG.0000000000000542
    PURPOSE: To evaluate the effect of nocturnal intermittent peritoneal dialysis (NIPD) on intraocular pressure (IOP) and anterior segment optical coherence tomography (ASOCT) parameters. Systemic changes associated with NIPD were also analyzed.

    METHODS: Observational study. Nonglaucomatous patients on NIPD underwent systemic and ocular assessment including mean arterial pressure (MAP), body weight, serum osmolarity, visual acuity, IOP measurement, and ASOCT within 2 hours both before and after NIPD. The Zhongshan Angle Assessment Program (ZAAP) was used to measure ASOCT parameters including anterior chamber depth, anterior chamber width, anterior chamber area, anterior chamber volume, lens vault, angle opening distance, trabecular-iris space area, and angle recess area. T tests and Pearson correlation tests were performed with P<0.05 considered statistically significant.

    RESULTS: A total of 46 eyes from 46 patients were included in the analysis. There were statistically significant reductions in IOP (-1.8±0.6 mm Hg, P=0.003), MAP (-11.9±3.1 mm Hg, P<0.001), body weight (-0.7±2.8 kg, P<0.001), and serum osmolarity (-3.4±2.0 mOsm/L, P=0.002) after NIPD. All the ASOCT parameters did not have any statistically significant changes after NIPD. There were no statistically significant correlations between the changes in IOP, MAP, body weight, and serum osmolarity (all P>0.05).

    CONCLUSIONS: NIPD results in reductions in IOP, MAP, body weight, and serum osmolarity in nonglaucomatous patients.

    Matched MeSH terms: Intraocular Pressure/physiology*
  9. Samsudin A, Eames I, Brocchini S, Khaw PT
    J Glaucoma, 2016 07;25(7):e704-12.
    PMID: 26561421 DOI: 10.1097/IJG.0000000000000360
    PURPOSE: Intraocular pressure and aqueous humor flow direction determined by the scleral flap immediately after trabeculectomy are critical determinants of the surgical outcome. We used a large-scale model to objectively measure the influence of flap thickness and shape, and suture number and position on pressure difference across the flap and flow of fluid underneath it.

    METHODS: The model exploits the principle of dynamic and geometric similarity, so while dimensions were up to 30× greater than actual, the flow had similar properties. Scleral flaps were represented by transparent 0.8- and 1.6-mm-thick silicone sheets on an acrylic plate. Dyed 98% glycerin, representing the aqueous humor was pumped between the sheet and plate, and the equilibrium pressure measured with a pressure transducer. Image analysis based on the principle of dye dilution was performed using MATLAB software.

    RESULTS: The pressure drop across the flap was larger with thinner flaps, due to reduced rigidity and resistance. Doubling the surface area of flaps and reducing the number of sutures from 5 to 3 or 2 also resulted in larger pressure drops. Flow direction was affected mainly by suture number and position, it was less toward the sutures and more toward the nearest free edge of the flap. Posterior flow of aqueous humor was promoted by placing sutures along the sides while leaving the posterior edge free.

    CONCLUSION: We demonstrate a new physical model which shows how changes in scleral flap thickness and shape, and suture number and position affect pressure and flow in a trabeculectomy.

    Matched MeSH terms: Intraocular Pressure/physiology*
  10. Chua J, Tham YC, Liao J, Zheng Y, Aung T, Wong TY, et al.
    Ophthalmology, 2014 Oct;121(10):2013-22.
    PMID: 24950592 DOI: 10.1016/j.ophtha.2014.04.041
    To determine the ethnic differences in the distribution of intraocular pressure (IOP) and central corneal thickness (CCT) in a multi-ethnic Asian population by self-reported ethnicity and genetic ancestry.
    Population-based, cross-sectional study.
    A total of 10 033 adults (3353 Chinese, 3280 Malays, and 3400 Indians) aged >40 years.
    Participants underwent standardized systemic and ocular examinations and interviewer-administered questionnaires for risk factor assessment. The IOP readings were obtained by Goldmann applanation tonometry (Haag-Streit, Konig, Switzerland) before pupil dilation. The CCT was measured with ultrasound pachymetry. Genetic ancestry was derived using principal component (PC) analysis. Regression models were used to investigate the association of IOP and CCT with potential risk factors and genetic ancestry.
    Intraocular pressure and CCT.
    After excluding participants with a history of glaucoma surgery or medication, refractive surgery, corneal edema, or corneal dystrophy, IOP and CCT readings were available for 3251 Chinese, 3232 Malays, and 3317 Indians. The mean IOP readings in the Chinese, Malay, and Indian participants were 14.3±3.1, 15.3±3.7, and 15.8±2.9 mmHg, respectively (P 
    Matched MeSH terms: Intraocular Pressure/physiology*
  11. Sharmini AT, Yin NY, Lee SS, Jackson AL, Stewart WC
    J Ocul Pharmacol Ther, 2009 Feb;25(1):71-5.
    PMID: 19232007 DOI: 10.1089/jop.2008.0061
    The aim of this study was to evaluate risk factors for progression in chronic angle-closure glaucoma (CACG) patients.
    Matched MeSH terms: Intraocular Pressure/physiology*
  12. Tajunisah I, Reddy SC, Fathilah J
    Graefes Arch. Clin. Exp. Ophthalmol., 2007 Dec;245(12):1851-7.
    PMID: 17901971
    BACKGROUND: A case-controlled prospective study was conducted to evaluate the diurnal variation of intraocular pressure (IOP); the mean, the amplitude of variation and the peak and trough times of pressure readings in the suspected open-angle glaucoma patients as compared with a control group. We also looked at the outcome of these suspects after diurnal variation of IOP measurements.

    METHODS: Diurnal variation of intraocular pressure was measured in 202 eyes of suspected open-angle glaucoma patients and 100 control eyes, at 4-hourly intervals for 24 hours (phasing). Based on the phasing results, optic disc changes and visual field defects, the patients were diagnosed as primary open angle glaucoma (POAG), normal tension glaucoma (NTG), ocular hypertension (OHT), or physiologic cup (PC), or still remained as glaucoma suspects due to inconclusive diagnosis. The last group (glaucoma suspects) was then followed up 6-monthly for their eventual outcome.

    RESULTS: The highest percentage of suspected glaucoma patients had peak (maximum) readings in the mid-morning (10-11 A.M.) and trough (minimum) readings after midnight (2-3 A.M.); the highest percentage of control group had peak readings in the late evening (6-7 P.M.) and trough readings after midnight (2-3 A.M.). The mean amplitude of variance was 6 mm Hg in suspected glaucoma group and 4 mm Hg in the control group. After 'phasing', 18.8% of the suspected glaucoma patients were diagnosed as POAG, 16.8% as NTG, 5% as OHT, and 28.7% as physiologic cup; 30.9% remained as glaucoma suspects. After 4 years follow-up, 70% of the glaucoma suspects still remained as glaucoma suspects, 6.7% developed NTG and another 6.7% POAG; 16.6% were normal.

    CONCLUSIONS: Serial measurement of IOP ( phasing) in a 24-hour period is still needed, in order not to miss the peak and the trough IOP readings in suspected open-angle glaucoma patients, which helps in better management of glaucoma. Among 30.9% of patients who remained as glaucoma suspects after the initial phasing, 13.4% developed NTG/POAG over a period of 4 years.

    Matched MeSH terms: Intraocular Pressure/physiology*
  13. Ramli N, Nurull BS, Hairi NN, Mimiwati Z
    Prev Med, 2013;57 Suppl:S47-9.
    PMID: 23352960 DOI: 10.1016/j.ypmed.2013.01.007
    In the absence of raised intraocular pressure (IOP), haemodynamic parameters have been implicated in the development of normal tension glaucoma (NTG). The purpose of this study is to compare 24-hour IOP and haemodynamic parameters in NTG patients and non-glaucoma patients.
    Matched MeSH terms: Intraocular Pressure/physiology
  14. Wong EY, Chew PT, Chee CK, Wong JS
    Am J Ophthalmol, 1997 Dec;124(6):797-804.
    PMID: 9402826
    PURPOSE: To evaluate the effectiveness and safety of diode laser contact transscleral cyclophotocoagulation in Asian patients with refractory glaucoma by lower energy settings with an innovative probe featuring a glass ball tip that focused the laser beam onto the ciliary body.

    METHODS: This prospective clinical study included consecutive Asian patients with dark irides and confirmed for glaucoma. Only one eye of each patient was treated. Diode laser contact transscleral cyclophotocoagulation treatment was performed with the center of the probe placed 1.5 mm behind the limbus. About 30 pulses of 810-mm laser radiation (power, 1.8 to 2.0 W; duration, 0.3 to 0.5 second) were applied around the eye. Patients were examined at fixed postoperative intervals. Intraocular pressure levels and postoperative complications were recorded. The relation between patient and disease characteristics, total laser energy delivered, and intraocular pressure effects were analyzed.

    RESULTS: Thirty-three patients were studied, with a mean follow-up period of 9.4 months. An average 56% of patients showed a 30% or greater drop in intraocular pressure. About 38% of patients achieved sustained intraocular pressure lowering to below 22 mm Hg at 18 months. Complications were few and included transient hypotony and iritis.

    CONCLUSIONS: In Asian patients with refractory glaucoma or painful glaucomatous eyes with poor visual acuity (defined for this study as worse than 20/200), low-energy-setting diode laser contact transscleral cyclophotocoagulation by means of the glass ball probe is relatively effective and safe.

    Matched MeSH terms: Intraocular Pressure/physiology
  15. Fang SY, Wan Abdul Halim WH, Mat Baki M, Din NM
    Graefes Arch. Clin. Exp. Ophthalmol., 2018 Apr;256(4):783-790.
    PMID: 29492688 DOI: 10.1007/s00417-018-3919-7
    PURPOSE: Obstructive sleep apnea syndrome (OSAS) patients are at risk of glaucoma but the risk increases if they have higher intraocular pressure (IOP) while sleeping. We aim to evaluate the postural effect of upright and prolong supine positions on IOP in these patients.

    METHODS: This is a cross-sectional study involving 27 patients with symptoms of OSAS seen at a tertiary institutional center and 25 normal controls performed between June 2015 and June 2016. All patients and controls underwent a polysomnography (PSG) test and were diagnosed with OSAS based on the apnea-hypopnea index (AHI). Patients are those with OSAS symptoms and had AHI > 5, whereas controls are staffs from the ophthalmology clinic without clinical criteria for OSAS and had PSG result of AHI

    Matched MeSH terms: Intraocular Pressure/physiology*
  16. Raman P, Suliman NB, Zahari M, Kook M, Ramli N
    Eye (Lond), 2018 07;32(7):1183-1189.
    PMID: 29491486 DOI: 10.1038/s41433-018-0057-8
    OBJECTIVE: To assess the relationship between baseline intraocular pressure (IOP), blood pressure (BP) and ocular perfusion pressure (OPP), and the 5-year visual field progression in normal-tension glaucoma (NTG) patients.

    DESIGN: Prospective, longitudinal study.

    METHODS: Sixty-five NTG patients who were followed up for 5 years are included in this study. All the enrolled patients underwent baseline 24-h IOP and BP monitoring via 2-hourly measurements in their habitual position and were followed up for over 5 years with reliable VF tests. Modified Anderson criteria were used to assess VF progression. Univariable and multivariable analyses using Cox's proportional hazards model were used to identify the systemic and clinical risk factors that predict progression. Kaplan-Meier survival analyses were used to compare the time elapsed to confirmed VF progression in the presence or absence of each potential risk factor.

    RESULTS: At 5-year follow-up, 35.4% of the enrolled patients demonstrated visual field progression. There were statistically significant differences in the mean diastolic blood pressure (p  43.7 mmHg (log rank = 0.018).

    CONCLUSION: Diastolic parameters of BP and OPP were significantly lower in the NTG patients who progressed after 5 years. Low nocturnal DOPP is an independent predictor of glaucomatous visual field progression in NTG patients.

    Matched MeSH terms: Intraocular Pressure/physiology*
  17. Ting SL, Lim LT, Ooi CY, Rahman MM
    Asia Pac J Ophthalmol (Phila), 2019 06 05;8(3):229-232.
    PMID: 31165604 DOI: 10.22608/APO.2018433
    PURPOSE: To compare the measurement of intraocular pressure (IOP) of Icare rebound tonometer and Perkins applanation tonometer (PAT) during community eye screening and to assess the agreement between these 2 instruments.

    DESIGN: A cross-sectional, non-interventional study.

    METHODS: The IOP measurements by handheld Icare rebound tonometer (Finland) were first performed by a primary care physician. Then the IOP was measured using Perkins Mk3 applanation tonometer (Haag-Streit, UK) by an ophthalmologist who was masked to previous readings from the Icare rebound tonometer. The mean IOP measured by each tonometer was compared. Pearson correlation coefficient was used to explore the correlation between the IOP measurements of the 2 instruments. The level of agreement between them was assessed using the Bland and Altman method.

    RESULTS: A total of 420 left eyes were examined. The mean age of subjects was 38.6 ± 18.2 years. Approximately 67% of subjects were female. The mean IOP was 16.3 ± 4.0 mm Hg using Icare and 13.4 ± 2.3 mm Hg using PAT. Pearson correlation coefficient showed a moderate positive correlation between the 2 methods (r = +0.524, P < 0.001). Linear regression analysis revealed a slope of 0.28 with R² of 0.255. The mean difference between the 2 methods was 2.90 ± 3.5 mm Hg and the sample t-test revealed a statistically significant mean difference from 0 (P < 0.001). The 95% limits of agreement between the 2 methods were between -9.73 and 3.93 mm Hg.

    CONCLUSIONS: The handheld Icare rebound tonometer is a reasonably acceptable screening tool in community practices. However, Icare overestimated IOP with a mean of 2.90 mm Hg higher than the PAT. Thus, using Goldmann applanation tonometer as a confirmatory measurement tool of IOP is suggested.

    Matched MeSH terms: Intraocular Pressure/physiology*
  18. Abdullah SN, Sanderson GF, Husni MA, Maddess T
    PMID: 32034583 DOI: 10.1007/s10633-020-09750-7
    PURPOSE: To compare two forms of perimetry that use large contrast-modulated grating stimuli in terms of: their relative diagnostic power, their independent diagnostic information about glaucoma and their utility for mfVEPs. We evaluated a contrast-threshold mfVEP in normal controls using the same stimuli as one of the tests.

    METHODS: We measured psychophysical contrast thresholds in one eye of 16 control subjects and 19 patients aged 67.8 ± 5.65 and 71.9 ± 7.15, respectively, (mean ± SD). Patients ranged in disease severity from suspects to severe glaucoma. We used the 17-region FDT-perimeter C20-threshold program and a custom 9-region test (R9) with similar visual field coverage. The R9 stimuli scaled their spatial frequencies with eccentricity and were modulated at lower temporal frequencies than C20 and thus did not display a clear spatial frequency-doubling (FD) appearance. Based on the overlapping areas of the stimuli, we transformed the C20 results to 9 measures for direct comparison with R9. We also compared mfVEP-based and psychophysical contrast thresholds in 26 younger (26.6 ± 7.3 y, mean ± SD) and 20 older normal control subjects (66.5 ± 7.3 y) control subjects using the R9 stimuli.

    RESULTS: The best intraclass correlations between R9/C20 thresholds were for the central and outer regions: 0.82 ± 0.05 (mean ± SD, p ≤ 0.0001). The areas under receiver operator characteristic plots for C20 and R9 were as high as 0.99 ± 0.012 (mean ± SE). Canonical correlation analysis (CCA) showed significant correlation (r = 0.638, p = 0.029) with 1 dimension of the C20 and R9 data, suggesting that the lower and higher temporal frequency tests probed the same neural mechanism(s). Low signal quality made the contrast-threshold mfVEPs non-viable. The resulting mfVEP thresholds were limited by noise to artificially high contrasts, which unlike the psychophysical versions, were not correlated with age.

    CONCLUSION: The lower temporal frequency R9 stimuli had similar diagnostic power to the FDT-C20 stimuli. CCA indicated the both stimuli drove similar neural mechanisms, possibly suggesting no advantage of FD stimuli for mfVEPs. Given that the contrast-threshold mfVEPs were non-viable, we used the present and published results to make recommendations for future mfVEP tests.

    Matched MeSH terms: Intraocular Pressure/physiology
  19. Niven TCS, Azhany Y, Rohana AJ, Karunakar TVN, Thayanithi S, Jelinar Noor MN, et al.
    J Glaucoma, 2019 01;28(1):7-13.
    PMID: 30461551 DOI: 10.1097/IJG.0000000000001120
    PURPOSE: The purpose of this study was to determine the association between cigarette smoking and the severity of primary angle closure glaucoma (PACG) in Malay patients residing in Malaysia.

    METHODS: A cross-sectional study was conducted involving 150 Malay PACG patients between April 2014 and August 2016. Ocular examination was performed including Humphrey visual field (HVF) 24-2 analysis assessment. On the basis of the 2 consecutive reliable HVFs, the severity of glaucoma was scored according to modified Advanced Glaucoma Intervention Study (AGIS) by 2 masked investigators and classified as mild, moderate, and severe. Those with retinal diseases, neurological diseases, memory problem, and myopia ≥4 diopters were excluded. Their smoking status and details were obtained by validated questionnaire from Singapore Malay Eye Study (SiMES). The duration of smoking, number of cigarettes per day, and pack/year was also documented. Multiple linear regression analysis was conducted.

    RESULTS: There was a significant association between education level and severity of PACG (P=0.001). However, there was no significant association between cigarette smoking and severity of glaucoma (P=0.080). On the basis of multivariate analysis, a linear association was identified between cigarette smoked per day (adjusted b=0.73; 95% CI: 0.54, 1.45; P<0.001) and body mass index (adjusted b=0.32; 95% CI: 0.07, 1.35; P=0.032) with AGIS score.

    CONCLUSIONS: There was no significant association between cigarette smoking and severity of PACG. Cigarette smoked per day among the smokers was associated with severity of PACG. However, because of the detrimental effect of smoking, cessation of smoking should be advocated to PACG patients.

    Matched MeSH terms: Intraocular Pressure/physiology
  20. Ashworth J, Flaherty M, Pitz S, Ramlee A
    Acta Ophthalmol, 2015 Mar;93(2):e111-7.
    PMID: 25688487 DOI: 10.1111/aos.12607
    Purpose: The mucopolysaccharidoses (MPS) are a group of rare lysosomal storage disorders, characterized by the accumulation of glycosaminoglycans within multiple organ systems including the eye. This study aimed to determine the prevalence of glaucoma in patients with MPS, as well as the characteristics, diagnosis and management of patients with MPS and glaucoma.
    Methods: A multicentre retrospective case-note review was carried out by ophthalmologists from four tertiary referral centres to identify patients with MPS who had been treated for glaucoma. Clinical ophthalmological data were collected using standardized data collection forms.
    Results: Fourteen patients were identified (27 eyes) of 294 patients with MPS. The prevalence of glaucoma ranged from 2.1% to 12.5%. The median age at diagnosis of glaucoma was 8 years. Diagnostic evaluation of glaucoma was incomplete in many patients: intraocular pressure was documented in all eyes, but optic disc appearance was only assessed in 67%, central corneal thickness in 26%, visual fields in 19% and iridocorneal angle in 15%.
    Conclusions: Patients with MPS need regular assessment for possible glaucoma including during childhood. Multiple factors contribute to the challenges of assessment, diagnosis and monitoring of glaucoma in these patients.
    Keywords: Hunter; Hurler; Hurler-Scheie; Maroteaux-Lamy; Morquio; Scheie; glaucoma; mucopolysaccharidosis; prevalence.
    Matched MeSH terms: Intraocular Pressure/physiology
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