Catherine Jui-Ling Liu

Varying Effects of Corneal Thickness on Intraocular Pressure Measurements with Different Tonometers

AbstractAimsTo compare the intraocular pressure (IOP) measurements using the Goldmann applanation tonometer (GAT), noncontact tonometer (NCT), and ocular blood flow tonometer (OBFT), and to evaluate the effects of varying central corneal thickness (CCT) on the readings.MethodsUltrasound pachymetry and tonometry were performed on 170 eyes. Using the corrected GAT values that took CCT into account as the standard, we calculated the NCT and OBFT measurement errors related to the CCT variable by a linear regression model. Group comparisons were performed with the χ2 test and one-way ANOVA test. The correlation between the various tonometer measurements was analysed by Pearsons correlation method.ResultsBoth the NCT (r=0.872, P<0.001) and OBFT measurements (r=0.861, P<0.001) were highly correlated with the GAT measurements. IOP measurements using the three tonometers were all correlated with CCT (all P<0.001), with the NCT measurements showing the greatest regression coefficient (β=0.063, r=0.650) and the GAT measurements the least (β=0.037, r=0.496). A linear regression model indicated that a 10 μm change in CCT resulted in a NCT measurement deviation of 0.47–0.98 mmHg and an OBFT measurement deviation of 0.29–0.81 mmHg.ConclusionPressure readings with the GAT, NCT, and OBFT are all affected by CCT, with the NCT being the one most affected and the GAT the least. Our findings suggest CCT an essential variable to consider in interpreting IOP readings, especially for the NCT measurements.

Changes in intraocular pressure and ocular perfusion pressure after latanoprost 0.005% or brimonidine tartrate 0.2% in normal-tension glaucoma patients

OBJECTIVE To evaluate and compare the effects of latanoprost 0.005% once daily and brimonidine tartrate 0.2% twice daily in patients with normal-tension glaucoma (NTG). DESIGN A randomized, open-label, crossover study. PARTICIPANTS Twenty-eight NTG patients with progressive visual field defects/optic disc excavation, new disc hemorrhage, or field defects that threatened fixation. INTERVENTION Patients were randomly allocated to one of two groups. Patients in group 1 were treated with latanoprost, lubricant, and brimonidine for 4 weeks each, whereas patients in group 2 were treated with brimonidine, lubricant, and latanoprost for 4 weeks each. MAIN OUTCOME MEASURES Intraocular pressure (IOP), pulse rate, and blood pressure were measured at 8 am, 12 noon, and 4 pm after each 4-week treatment. Ocular perfusion pressure (OPP) was calculated. RESULTS Latanoprost and brimonidine reduced the average IOP by 3.6 +/- 1.9 mmHg (P < 0.001) and 2.5 +/- 1.3 mmHg (P < 0.001), respectively, with a significant difference between the two regimens (P = 0.009). Both drugs significantly reduced IOP at each time point. Latanoprost decreased IOP significantly more than did brimonidine at 8 am (11.7 +/- 2.2 mmHg vs. 13.7 +/- 2.1 mmHg, P = 0.004) and 4 pm (11.4 +/- 2.1 mmHg vs. 13.2 +/- 2.9 mmHg, P = 0.004), but IOP was equal between the two agents at 12 noon (11.5 +/- 2.6 mmHg vs. 11.5 +/- 2.3 mmHg, P = 0.967). IOP was maintained at 12 mmHg or lower in 18 (66.7%) of 27 patients after treatment with latanoprost and in 9 (33.3%) of 27 patients after treatment with brimonidine. Latanoprost monotherapy reduced IOP by 30% in 8 patients (29.6%), but brimonidine monotherapy did not reduce IOP by that much in any of the patients. OPP increased after latanoprost treatment (P < 0.001) but did not increase after brimonidine treatment (P = 0.355). There was no significant change in pulse rate or blood pressure. CONCLUSIONS Both latanoprost and brimonidine reduce IOP in NTG patients. Brimonidine has a peak IOP-lowering effect equal to that of latanoprost but produces a higher mean diurnal IOP than does latanoprost because of its shorter effect. Latanoprost might favorably alter optic disc blood perfusion by increasing OPP.

Sustained delivery of latanoprost by thermosensitive chitosan-gelatin-based hydrogel for controlling ocular hypertension

Glaucoma is an irreversible ocular disease that may lead to progressive visual field loss and eventually to blindness with inadequately controlled intraocular pressure (IOP). Latanoprost is one of the most potent ocular hypotensive compounds, the current first-line therapy in glaucoma. However, the daily instillation required for efficacy and undesirable side-effects are major causes of treatment adherence failure and persistence in glaucoma therapy. In the present study, we developed an injectable thermosensitive chitosan/gelatin/glycerol phosphate (C/G/GP) hydrogel as a sustained-release system of latanoprost for glaucoma treatment. The latanoprost-loaded C/G/GP hydrogel can gel within 1min at 37°C. The results show a sustained release of latanoprost from C/G/GP hydrogel in vitro and in vivo. The latanoprost-loaded C/G/GP hydrogel showed a good in vitro and in vivo biocompatibility. A rabbit model of glaucoma was established by intravitreal injection of triamcinolone acetonide. After a single subconjunctival injection of latanoprost-loaded C/G/GP hydrogel, IOP was significantly decreased within 8days and then remained at a normal level. The results of the study suggest that latanoprost-loaded C/G/GP hydrogel may have a potential application in glaucoma therapy.

Power vector analysis of refractive, corneal, and internal astigmatism in an elderly Chinese Population: The Shihpai Eye Study

PURPOSE To investigate age-related trends in refractive, corneal, and internal astigmatism and to assess the association between internal astigmatism and lens opacity in an elderly Chinese population. METHODS A population-based study was conducted among 1360 inhabitants aged 65 years and older in Taipei, Taiwan. Participants underwent measurements of refraction, corneal dioptric power, and slit lamp biomicroscopy with lens grading. A total of 2084 eyes were included in power vector analyses of Cartesian astigmatism (J(0)) and oblique astigmatism (J(45)) components of refractive, corneal, and internal astigmatism. RESULTS The crude prevalence of refractive astigmatism (defined as ≥0.75 diopters) was 73.0% based on the right eyes and 76.4% based on the left eyes. The vector values in both refractive J(0) and corneal J(0) tended to be more negative with increasing age (P < 0.001), indicating the trend toward against-the-rule (ATR) astigmatism. Corneal J(0) alone accounted for 54% of the variability in refractive J(0). Refractive J(45) increased with age in the right eyes (P < 0.001) and decreased slightly with age in the left eyes (P = 0.012). Cortical opacity was associated with internal J(0) (P = 0.025), but the association was weak. CONCLUSIONS Astigmatism affects approximately three quarters of the Chinese population aged 65 years and older in Taiwan. With increasing age, the prevalence of astigmatism increases, and refractive and corneal astigmatism shift toward ATR. Continuous corneal changes appear to be responsible for the age trend in refractive astigmatism. The severity of lens opacity plays only a minor role in the change of internal astigmatism.

Combined Trabeculectomy and Cataract Extraction versus Trabeculectomy Alone in Primary Angle-Closure Glaucoma

Aims: To compare the long-term efficacy and safety of combined trabeculectomy and cataract extraction versus trabeculectomy alone in primary angle-closure glaucoma (PACG). Methods: Hospital files were retrospectively examined for 99 Chinese PACG patients; 75 patients underwent combined surgery and 24 underwent trabeculectomy alone. Success rates were assessed with the Kaplan–Meier survival analysis. The main outcome was the complete success rate defined as either a >20% reduction in intraocular pressure (IOP) or an IOP that remained below 15 mm Hg, with no medications required. Results: Patients in the combined group and trabeculectomy group had a mean follow-up period of 25.8 (SD 10.8) months and 31.4 (8.9) months, respectively. Survival analysis showed that the complete success rate at 3 years was 56% in the combined group and 54% in the trabeculectomy group (p = 0.903). There were no significant differences between groups in either IOP or the number of glaucoma medications throughout the 3-year follow-up. The incidences of postoperative complications were similar between groups (p = 0.232). No additional IOP-lowering surgical procedures were required in the combined group, while 13 (54%) eyes in the trabeculectomy group required either cataract extraction or further IOP-lowering surgical procedures (p <0.001). Conclusion: In patients with PACG, the long-term IOP-lowering effect and surgical complications of combined trabeculectomy and cataract extraction are comparable with those of trabeculectomy alone. However, the combined surgery incurred fewer subsequent surgical interventions.

Patterns of visual field defects in chronic angle-closure glaucoma with different disease severity.

PURPOSE To evaluate the patterns of visual field defects in patients with chronic angle-closure glaucoma (CACG) with varying extent of optic nerve damage. DESIGN Prospective, consecutive, observational case series. PARTICIPANTS One hundred forty-six Asian patients with well-controlled CACG. METHODS Visual field tests were performed using program 24-2 of the Humphrey Field Analyzer (Humphrey Instruments, San Leandro, CA) with the Swedish interactive thresholding algorithm standard. One hundred ten eligible visual fields were scored with the system adopted by the Advanced Glaucoma Intervention Study and were categorized into 4 groups accordingly: mild, moderate, severe, and end-stage. Each hemifield was divided into the nasal, paracentral, and arcuate areas, and field loss that involved respective areas was defined as nasal step, paracentral scotoma, and arcuate scotoma. MAIN OUTCOME MEASURES The distribution of field defect patterns in each group was evaluated. The mean deviation (MD) was compared among the 3 areas within one hemifield and between each pair of corresponding areas across the median raphe. RESULTS The nasal area was the most commonly damaged area in the mild group, being noted in 52% of eyes in the superior hemifield and 58% of eyes in the inferior hemifield. In the moderate group, field loss involving both the nasal and arcuate areas dominated the superior hemifield, whereas field loss involving all three areas dominated the inferior hemifield. The MD of the nasal area was the worst among the three areas in each hemifield of the mild and moderate groups, as well as in the inferior hemifield of the severe group (all P < 0.001). There were no significant differences in the MD of each area between the superior hemifield and their inferior counterparts. However, the superior hemifield as a whole showed a better MD than the inferior hemifield (P=0.034) in the mild group. CONCLUSIONS Visual field loss that involved the nasal area was the most common pattern in the early stage of CACG. The MD of the nasal area was worse than those of the arcuate and the paracentral areas within the same hemifield in the mild, moderate, and severe groups of CACG patients.

Color Doppler imaging study of retrobulbar hemodynamics in chronic angle-closure glaucoma.

PURPOSE To evaluate the retrobulbar hemodynamics in patients with chronic angle-closure glaucoma (CACG) by using color Doppler imaging (CDI) and to correlate the degree of glaucomatous visual field loss with the hemodynamic parameters. DESIGN Prospective case series. PARTICIPANTS AND CONTROLS Twenty-six Chinese patients with CACG and 26 age-matched and gender-matched normal subjects were recruited. All CACG patients had history of chronic intraocular pressure (IOP) elevation and asymmetric visual field defects between their fellow eyes. After receiving laser peripheral iridotomy and/or filtration surgery, all of them had bilateral medication-free controlled IOP before enrolling into the study. METHODS Each subject underwent CDI measurement in the central retinal artery (CRA) and the nasal and temporal short posterior ciliary arteries (PCA). Visual fields of the CACG patients were obtained with Humphrey 24-2 program. The visual field defects were scored with the Advanced Glaucoma Intervention Study (AGIS) system. For each CACG patient, the eye with lower AGIS score was defined as the better eye and the eye with higher score as the worse eye. MAIN OUTCOME MEASURES Peak-systolic velocity (PSV), end-diastolic velocity (EDV) and resistance index (RI) were determined. RESULTS The EDV in the CRA and the temporal PCA was decreased significantly (P = 0.041 and 0.023, respectively) in the worse eyes of CACG patients compared with those in the control eyes. The better eyes of CACG patients showed no significant change in hemodynamic parameters compared with the control eyes. While comparing the fellow eyes of CACG patients, the worse eyes had significantly lower EDV in the temporal PCA (P = 0.012) than the contralateral better eyes. In 11 CACG patients with a difference of at least 8 in AGIS visual field scores between their fellow eyes, the worse eyes had significantly lower EDV (P = 0.041) in the CRA and lower PSV (P = 0.018) and EDV (P = 0.018) in the temporal PCA compared with those in the contralateral eyes. In multivariate regression analysis, the AGIS scores were significantly correlated with the PSV in the CRA (P = 0.015) and with the EDV (P < 0.001) and RI (P = 0.027) in the temporal PCA in patients with CACG. CONCLUSIONS Patients with well-controlled CACG may have decreased retrobulbar blood flow velocities and increased vascular resistance in the CRA and temporal PCA. The degree of retrobulbar hemodynamic impairment was well correlated with the degree of glaucomatous visual field loss.

Determinants of long-term intraocular pressure after phacoemulsification in primary angle-closure glaucoma.

AimsTo determine the preoperative factors associated with long-term intraocular pressure (IOP) after cataract surgery in primary angle-closure glaucoma (PACG). MethodsThe data of 56 PACG patients who had undergone phacoemulsification consecutively were analyzed after detailed chart review. The associations between postoperative IOP and various preoperative factors were determined by multivariate linear regression analyses. ResultsThe mean postoperative follow-up was of 33.0±13.6 months. The postoperative IOP decreased (P<0.05 at each visit) from the preoperative level over the years, with a mean percent reduction of 20%. Glaucoma medication number also reduced significantly, except at month 30 (P=0.088), 36 (P=0.585), and 48 (P=0.104). Preoperative factors of higher IOP (P<0.001) and deeper anterior chamber depth (ACD) (P=0.006) were associated with higher postoperative IOP over the years. The multiplication product IOP×ACD accounted for 49% of the IOP variations 1 year after surgery, and eyes with this index less than or equal to 35 were more likely to achieve postoperative IOP readings of less than or equal to 12 mm Hg (odds ratio, 9.2, P=0.001) than those with an index more than 35. ConclusionsLong-term IOP after phacoemulsification in PACG is positively associated with preoperative IOP and preoperative ACD.

Patient-Reported Vision-Related Quality of Life Differences Between Superior and Inferior Hemifield Visual Field Defects in Primary Open-Angle Glaucoma

IMPORTANCE Previous studies have found that glaucoma is associated with impaired patient-reported vision-related quality of life (pVRQOL) but few, to our knowledge, have assessed how the visual field (VF) defect location impacts the pVRQOL. OBJECTIVE To investigate the associations of VF defects in the superior vs inferior hemifields with pVRQOL outcomes in patients with primary open-angle glaucoma. DESIGN, SETTING, AND PARTICIPANTS Prospective cross-sectional study at a tertiary referral center from March 1, 2012, to January 1, 2013, including patients with primary open-angle glaucoma who had a best-corrected visual acuity in the better eye equal to or better than 20/60 and reliable VF tests. The pVRQOL was assessed by a validated Taiwanese version of the 25-item National Eye Institute Visual Function Questionnaire. Reliable VF tests obtained within 3 months of enrollment were transformed to binocular integrated VF (IVF). The IVF was further stratified by VF location (superior vs inferior hemifield). MAIN OUTCOMES AND MEASURES The association between each domain of the 25-item National Eye Institute Visual Function Questionnaire and superior or inferior hemifield IVF was determined using multivariable linear regression analysis. RESULTS The analysis included 186 patients with primary open-angle glaucoma with a mean age of 59.1 years (range, 19-86 years) and IVF mean deviation (MD) of -4.84 dB (range, -27.56 to 2.17 dB). In the multivariable linear regression analysis, the MD of the full-field IVF showed positive associations with near activities (β = 0.05; R2 = 0.20; P < .001), vision-specific role difficulties (β = 0.04; R2 = 0.19; P = .01), vision-specific dependency (β = 0.04; R2 = 0.20; P < .001), driving (β = 0.05; R2 = 0.24; P < .001), peripheral vision (β = 0.03; R2 = 0.18; P = .02), and composite scores (β = 0.04; R2 = 0.27; P = .005). Subsequent analysis showed that the MD of the superior hemifield IVF was associated only with near activities (β = 0.04; R2 = 0.21; P < .001) while the MD of the inferior hemifield IVF was associated with general vision (β = 0.04; R2 = 0.12; P = .01), vision-specific role difficulties (β = 0.04; R2 = 0.20; P = .01), and peripheral vision (β = 0.03; R2 = 0.17; P = .03). CONCLUSIONS AND RELEVANCE Superior hemifield IVF was strongly associated with difficulty with near activities. Inferior hemifield IVF impacted vision-specific role difficulties and general and peripheral vision. The impact of a VF defect on a patients pVRQOL may depend not only on its severity, but also on its hemifield location.

The effect of photo-oxidative stress and inflammatory cytokine on complement factor H expression in retinal pigment epithelial cells.

PURPOSE Genetic variation in complement factor H (CFH) has been implicated as a major risk factor for age-related macular degeneration (AMD). The reduction in CFH amount or its complement-modulating activity may lead to inadequate control of complement-driven inflammation at the outer retina. We explored the effect of photo-oxidative stress and inflammatory cytokine on the expression of CFH in retinal pigment epithelial (RPE) cells. METHODS Cultured human RPE cells were exposed to blue light in the presence of interferon-γ (IFN-γ). CFH expression in cell lysate was examined by Western blot and the secretory CFH in culture medium was analyzed by ELISA. RPE cells were treated with vitamin C and exogenous superoxide dismutase mimetic (Tempol) before photo-oxidative treatments. The intracellular reactive oxygen species were examined by flow cytometry. RESULTS IFN-γ increased CFH expression in RPE and the expression was suppressed significantly under concomitant blue light illumination. The secretory CFH level also decreased significantly under blue light illumination, which was related to the decreased intracellular mRNA and protein expressions of CFH. The suppression was mediated through an oxidative mechanism, and was particularly related to superoxide anion generation. The suppression of CFH expression in RPE under blue light illumination was abrogated by vitamin C and Tempol. CONCLUSIONS Photo-oxidative stress reduces the ability of IFN-γ to increase CFH expression in RPE. Apart from reducing the oxidative damage, vitamin C reduces the suppression of CFH under photo-oxidative stress. These results suggest a new perspective of the interaction between oxidative stress and inflammation, and provide a potential novel treatment strategy for age-related macular degeneration.