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.
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.
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.
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
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.
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.
PURPOSE: The purpose of this study was to investigate the clinical characteristics, including 24-hour ocular perfusion pressure and risk of progression in patients with baseline central VF defect, as compared with those with peripheral VF defect in NTG.
DESIGN: This was a prospective, longitudinal study.
METHODS: A total of 65 NTG patients who completed 5 years of follow-up were included in this study. All the enrolled patients underwent baseline 24-hour intraocular pressure and blood pressure monitoring via 2-hourly measurements in their habitual position and had ≥5 reliable VF tests during the 5-year follow-up. Patients were assigned to two groups on the basis of VF defect locations at baseline, the central 10 degrees, and the peripheral 10- to 24-degree area. Modified Anderson criteria were used to assess global VF progression over 5 years. Kaplan-Meier analyses were used to compare the elapsed time of confirmed VF progression in the two groups. Hazard ratios for the association between clinical risk factors and VF progression were obtained by using Cox proportional hazards models.
RESULTS: There were no significant differences between the patients with baseline central and peripheral VF defects in terms of demography, clinical, ocular and systemic hemodynamic factors. Eyes with baseline defects involving the central fields progressed faster (difference: βcentral=-0.78 dB/y, 95% confidence interval=-0.22 to -1.33, P=0.007) and have 3.56 times higher hazard of progressing (95% confidence interval=1.17-10.82, P=0.025) than those with only peripheral defects.
CONCLUSION: NTG patients with baseline central VF involvement are at increased risk of progression compared with those with peripheral VF defect.
METHODS: This retrospective study analysed data of 60 eyes from 30 patients with bilateral uveitic glaucoma who had undergone glaucoma surgery in both eyes on separate occasions. Humphrey VF progression was assessed using the Progressor software.
RESULTS: The pre-operative IOP between the FE (43.1 ± 7.7 mmHg) and SE (40 ± 8.7 mmHg) was not statistically significant (p = 0.15). IOP reduction was greater in the FE (64 %) than SE (59.7 %) post-operatively, but the mean IOP at the final visit in the FE (12.3 ± 3.9 mmHg) and SE (14.5 ± 7 mmHg) was not statistically different (p = 0.2). There was no significant change in mean logMAR readings pre and post-operatively (0.45 ± 0.6 vs 0.37 ± 0.6, p = 0.4) or between the FE and SE. The number of SE with CDR > 0.7 increased by 23 % compared to the FE. From 23 available VFs, five SE (21.7 %) progressed at a median of five locations (range 1-11 points) with a mean local slope reduction of 1.74 ± 0.45 dB/year (range -2.39 to -1.26), whereas only one FE progressed. However, there was no significant difference between mean global rate of progression between the FE (-0.9 ± 1.6 dB/year) and SE (-0.76 ± 2.1 dB/year, p = 0.17) in the Humphrey VF.
CONCLUSION: In eyes with bilateral uveitic glaucoma requiring glaucoma surgery, the SEs had more progressed points on VF and glaucomatous disc progression compared to FEs at the final visit.
AIM: Aging-associated CI can impair the ability of individuals to perform a VF test and compromise the reliability of the results. We evaluated the association between neurocognitive impairment and VF reliability indices in glaucoma patients.
METHODS: This prospective, cross-sectional study was conducted in the Ophthalmology Department, Hospital Kuala Pilah, Malaysia, and included 113 eyes of 60 glaucoma patients with no prior diagnosis of dementia. Patients were monitored with the Humphrey Visual Field Analyzer using a 30-2 SITA, standard protocol, and CI was assessed using the clock drawing test (CDT). The relationships between the CDT score, MD, pattern standard deviation, Visual Field Index (VFI), fixation loss (FL), false-positive values, and FN values were analyzed using the ordinal regression model.
RESULTS: Glaucoma patients older than 65 years had a higher prevalence of CI. There was a statistically significant correlation between CDT scores and glaucoma severity, FL, FN, and VFI values (rs=-0.20, P=0.03; rs=-0.20, P=0.04; rs=-0.28, P=0.003; rs=0.21, P=0.03, respectively). In a multivariate model adjusted for age and glaucoma severity, patients with lower FN were significantly less likely to have CI (odds ratio, 0.91; 95% confidence interval, 0.89-0.93) and patients with higher MD were more likely to have CI (odds ratio, 1.10; 95% confidence interval, 1.05-1.16); false positive, FL, pattern standard deviation, and VFI showed no significant correlation.
CONCLUSION: Cognitive decline is associated with reduced VF reliability, especially with higher FN rate and overestimated MD. Screening and monitoring of CI may be important in the assessment of VF progression in glaucoma patients.