The Effect of Diurnal Fluctuation in Intraocular Pressure on the Evaluation of Risk Factors of Progression in Normal Tension Glaucoma.

PURPOSE: To investigate whether diurnal fluctuation in intraocular pressure (IOP) can influence the result of the correlations between IOP-related factors and progression of normal tension glaucoma (NTG). METHODS: Glaucoma progression was defined as visual field (VF) progression and changes in the optic disc and/or retinal nerve fiber layer (RNFL). Two different methods were used to evaluate the impact of the diurnal fluctuation in IOP. 'Conventional method' used in previous studies included all IOP measurements during the follow up time. 'Time adjusted method' was used to adjust diurnal fluctuation in IOP with the preferred time. Mean IOP, long term IOP fluctuation and the difference between the lowest and highest IOP were calculated using both methods. Cox regression analyses were performed to evaluate the association between IOP-related factors and NTG progression. RESULTS: One hundred and forty eyes of 140 patients with NTG were included in this study. 41% (58 of 140 eyes) of eyes underwent NTG progression. Long term IOP variation calculated by conventional method was not a significant risk factor for NTG progression (hazard ratio[HR], 0.311; 95% confidence interval[CI], 0.056-1.717; P = 0.180). Long term IOP variation calculated by time adjusted method, however, was related to progression, with an HR of 5.260 (95% CI,1.191-23.232; P = 0.029). CONCLUSION: Although having the same IOP-related factors, if diurnal fluctuation is included, different results may be found on the relationship between IOP-related factors and NTG progression. Based on our results, diurnal fluctuation in IOP should be considered when IOP-related factors are studied in the future.

Performance of and Pressure Elevation Formed by Small-diameter Microtubes Used in Constant-flow Sets.

PURPOSE: We explored the performance of and pressure elevation caused by small-diameter microtubes used to reduce overfiltration. METHODS: Using a syringe pump-driven constant-flow setting (2 µL/min), pressures were measured for polytetrafluoroethylene (PTFE) microtubes 5 mm in length with inner diameters of 51, 64, and 76 µm and for polyether block amide (PEBAX) microtubes with an inner diameter of 76 µm. Experiments (using microtubes only) were initially performed in air, water, and enucleated pig eyes and were repeated under the same conditions using intraluminal 9/0 nylon stents. RESULTS: The pressures measured in air in 51-, 64-, and 76-µm-diameter PTFE microtubes differed significantly (22.1, 16.9, and 12.2 mmHg, respectively; p < 0.001), and that of the 76-µm-diameter PEBAX microtube was 15.8 mmHg (p < 0.001 compared to the 12.2 mmHg of the 76-µm-diameter PTFE microtube). The pressures measured in water also differed significantly among the three microtubes at 3.9, 3.0, and 1.4 mmHg, respectively, while that in the PEBAX microtube was 2.6 mmHg (all p < 0.001). Using the intraluminal stent, the pressure in water of the three different PTFE microtubes increased to 22.6, 18.0, and 4.1 mmHg, respectively, and that in the PEBAX microtube increased to 10.5 mmHg (all p < 0.001). Similar trends were evident when measurements were performed in pig eyes. CONCLUSIONS: Although microtubes of smaller diameter experienced higher pressure in air, reduction of the inner diameter to 51 µm did not adequately increase the pressure attained in water or pig eyes. Insertion of an intraluminal stent effectively elevated the latter pressures. PEBAX microtubes created higher pressures than did PTFE microtubes.

Changes of choroidal thickness, intraocular pressure and other optical coherence tomographic parameters after haemodialysis.

BACKGROUND: The aim was to evaluate changes in choroidal thickness, intraocular pressure (IOP) and other parameters of optical coherence tomography, such as central foveal thickness (CFT), macular volume, peripapillary retinal nerve fibre layer (RNFL) thickness after haemodialysis (HD). METHODS: Thirty-four eyes of 34 chronic renal failure patients (9 eyes with diabetic patients) who underwent haemodialysis in the Dialysis Unit of Gangneung Asan Hospital were included. CFT, macular volume, peripapillary RNFL and choroidal thickness were measured before and after haemodialysis by optical coherence tomography (OCT, Spectralis; Heidelberg Engineering). Changes in the IOP were evaluated with Goldmann applanation tonometry before and after haemodialysis. RESULTS: The average choroidal thickness decreased significantly, from 233.1 ± 77.5 µm to 219.1 ± 76.8 µm (paired t-test, p < 0.001). This change correlated with the amount of body weight lost (Pearson's correlation coefficient = 0.348, p = 0.044). The mean IOP decreased from 15.1 ± 2.6 mmHg to 13.9 ± 2.2 mmHg after haemodialysis (paired t-test, p = 0.03). The change in macular volume and the small decrease in CFT (214.0 ± 21.0 µm to 213.8 ± 21.8 µm) were not significant. The measured overall change in RNFL thickness from 93.6 ± 15.5 µm to 94.7 ± 14.6 µm was not significant. CONCLUSIONS: Haemodialysis can affect various ocular parameters, particularly choroidal thickness and IOP.

Effect of Ginkgo biloba extract on visual field progression in normal tension glaucoma.

PURPOSE: To evaluate the long-term effect of Ginkgo biloba extract (GBE) on progression of visual field (VF) defects in patients with normal tension glaucoma (NTG). METHODS: Forty-two eyes of 42 patients with treated NTG who received 80 mg GBE 2 times daily and who had at least 5 VF tests using the Humphrey Visual Field Analyzer for more than a 4-year period before and after GBE treatment were evaluated in this retrospective study. We evaluated the change of progression rate using mean deviation (MD), pattern standard deviation (PSD), and visual field index (VFI) after GBE treatment. The time course of mean total deviation in 10 zones corresponding to the glaucoma hemifield test was analyzed using a linear mixed effects model with unequal random effect variances. RESULTS: The mean follow-up period was 12.3 years. The posttherapeutic intraocular pressures before and after GBE treatment were not significantly different (P=0.509 paired t test). Before GBE treatment, the regression coefficients (RCs) of MD, PSD, and VFI change were -0.619 dB/y, 0.626 dB/y, and -2.153%/y, respectively. After GBE treatment, the RCs of MD, PSD, and VFI change improved significantly to -0.379 dB/y, 0.342 dB/y, and -1.212%/y (P <0.001), respectively. In zone 1, the RC of mean total deviation change was significantly increased after GBE administration (P <0.005). CONCLUSIONS: GBE administration slowed the progression of VF damage in patients with NTG, especially in zone 1 corresponding to the superior central field.

Surgical outcome of mitomycin C-soaked collagen matrix implant in trabeculectomy.

PURPOSE: To assess the surgical outcomes and wound healing reaction of a filtering bleb after trabeculectomy using mitomycin C-soaked biodegradable collagen matrix (ologen). METHODS: Thirty eyes, in which the intraocular pressure (IOP) could not be controlled within the proper range by medication or laser treatment, were targeted in this study. After trabeculectomy with mitomycin C (0.2 mg/mL, 0.1 mL)-soaked ologen, surgical outcomes were assessed by evaluating bleb morphology by the Moorfield bleb grading system, as well as internal reflectivity and wound healing response of the bleb using a slit lamp and ultrasound biomicroscopy. The follow-up period continued for 12 months after surgery. RESULTS: Twelve months after surgery, 12/30 (40.0%) eyes were considered complete successes and 24/30 (80%) eyes as qualified successes. This rate is similar to the rate of our conventional trabeculectomy. The encapsulated bleb was the most frequent complication (9 eyes) and generally occurred at approximately 2 weeks after surgery. No avascular blebs were observed at final follow-up. CONCLUSIONS: Trabeculectomy with mitomycin C-soaked ologen do not seem to exert any synergistic effect with antimetabolites in terms of a reduction in IOP. However, the mitomycin C-soaked collagen matrix implant used in trabeculectomy resulted in comparatively stable IOP and did not aggravate wound healing or scar formation. Encapsulated blebs were generated at a more rapid pace in larger amounts compared with conventional trabeculectomy. The management of encapsulated blebs may be crucial to improving the success rate of surgery.

Influence of the extent of myopia on the progression of normal-tension glaucoma.

PURPOSE: To evaluate the influence of the extent of myopia on the progression rate of normal-tension glaucoma (NTG). DESIGN: Retrospective, observational case series. METHODS: One hundred forty-three eyes of 143 patients with NTG who were treated from 1994 through 2006 and followed up with standard automated perimetry were evaluated in this study. The participants were divided into 4 groups: mild myopia (-0.76 to -2.99 diopters [D]), moderate myopia (-3 to -5.99 D), severe myopia (-6 D or less), and nonmyopia (emmetropia and hyperopia, -0.75 D or more) groups. The change in mean deviation, corrected pattern standard deviation, mean thresholds of 10 zones corresponding to the glaucoma hemifield test, and thresholds of 52 points of the nonmyopia group were compared with those of the other myopia groups. Additionally, we controlled each analysis for age and posttherapeutic intraocular pressure to preclude the possibility of these covariates influencing the analysis of the effect of myopia on the progression of glaucoma. RESULTS: There was no statistically significant difference between the nonmyopia group and each of the myopia groups in terms of mean deviation, corrected pattern standard deviation, mean thresholds of 10 zones corresponding to the glaucoma hemifield test, and the thresholds of 52 point changes against refraction. Moreover, with the control of the other covariates (age and posttherapeutic intraocular pressure), no statistically significant differences were noted (multivariate analysis using mixed model, P > .1). CONCLUSIONS: Although a high incidence of open-angle glaucoma among myopic patients has been reported previously, myopia did not influence the progression rate of NTG after treatment.