Yu-Chieh Ko

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.

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.

Factors related to corneal endothelial damage after phacoemulsification in eyes with occludable angles

PURPOSE: To evaluate the influence of preoperative variables and early postoperative intraocular pressure (IOP) on the loss of corneal endothelial cells after phacoemulsification in eyes with occludable angles. SETTING: Taipei Veterans General Hospital, Taipei, Taiwan. METHODS: Sixty patients with occludable angles having phacoemulsification were prospectively enrolled. Corneal endothelial cell evaluation was conducted preoperatively and 3 months postoperatively. RESULTS: Three months postoperatively, the mean corneal endothelial cell density decreased by 14.5% ± 25.8% (SD) (P < .001). Greater corneal endothelial cell loss was associated with shorter axial length (AL) (P = .008), steeper anterior corneal curvature (P = .03), greater nuclear opalescence (P = .04), and higher IOP measured 4 to 8 hours after surgery (P = .04) and the following morning (P = .002). Multiple linear regression analysis identified AL and the IOP measured 4 to 8 hours after surgery as the best predictors of postoperative corneal endothelial cell loss after adjusting for nuclear opalescence and phacoemulsification time (R2 = 0.40, P = .001). CONCLUSIONS: The corneal endothelial cell loss after phacoemulsification in eyes with occludable angles was associated with preoperative AL measurement and postoperative IOP within 24 hours. To minimize corneal endothelial cell damage, it is critical to avoid an IOP spike during the early postoperative period and to exercise extreme caution intraoperatively in eyes with an AL less than 22.6 mm.

Comparisons of Risk Factors and Visual Field Changes between Juvenile-Onset and Late-Onset Primary Open-Angle Glaucoma

Purpose: To identify the differences in risk factors and visual field (VF) changes between juvenile primary open-angle glaucoma (JOAG) and late-onset chronic open-angle glaucoma (COAG). Methods: The demographic and presenting clinical data of 27 JOAG and 30 COAG patients were retrospectively reviewed. Comparisons between the two groups were performed using Mann-Whitney U test, Wilcoxon signed-rank test, and Fisher’s exact test. Results: A family history of glaucoma (37%) and a history of steroid usage (14.8%) were identified in JOAG patients only. The JOAG patients had a longer axial length (p < 0.001) and more often a myopic refractive state (p < 0.001) than the COAG patients. Patients with COAG showed a deeper (p = 0.016) and a more extensive (p = 0.008) defect in the superior than in the inferior hemifield, as well as a deeper (p = 0.016) and a more extensive (p = 0.001) defect in the superior than in the inferior arcuate area, while JOAG patients showed symmetric VF defects between the superior and inferior hemifields. Purely diffuse VF depression is more common in JOAG than in COAG patients (p = 0.03). Conclusions: JOAG patients demonstrated more axial myopic changes than patients with COAG as well as a pattern of superior-inferior symmetric VF defects. Axial myopia may play a critical role in the pathogenesis of JOAG.

Elevated nitric oxide level in aqueous humor of AIDS patients with cytomegalovirus retinitis.

Human cytomegalovirus (HCMV) retinitis is the most common ocular opportunistic infection in AIDS. It often leads to blindness if left untreated. The questions as to how HCMV infection causes retinal immunopathogenesis and visual destruction in AIDS patients have not been completely established. Here we reported that the nitric oxide (NO) levels in aqueous humor samples in 10 AIDS patients with CMV retinitis (104.3 ± 27.1 µM) were higher than the levels in 7 AIDS patients without CMV retinitis (36.1 ± 10.4 µM; p < 0.001). After ganciclovir treatment, the NO level in the vitreous body of 5 patients declined dramatically (53.4 ± 11.8 µM). By using immunohistochemistry assay, we found that the aggregates of macrophages infiltrated in the CMV-infected retina of 4 AIDS patients. Moreover, the expression of inducible-form NO synthase was detected in the infected retina of these patients. These results suggest that NO production in the eye may play a fundamental role in the immunopathogenesis of AIDS patients with CMV retinitis.

Seven-Year Incidence of Age-Related Cataracts Among an Elderly Chinese Population in Shihpai, Taiwan: The Shihpai Eye Study

PURPOSE To report the 7-year incidence of age-related cataracts in a metropolitan Chinese elderly population. METHODS The Shihpai Eye Study 2006 included 460 (55.8%) of 1361 participants in the 1999 baseline survey for a follow-up eye examination. Cataract was graded by one ophthalmologist using the Lens Opacities Classification System III. RESULTS The 7-year incidence of pure nuclear opacity was 18.5% (95% confidence interval [CI]: 12.7%-24.3%)]; 34.7% (95% CI: 27.6%-41.8%) for cortical opacity; and 0.6% (95% CI: 0%-1.8%) for posterior subcapsular opacity. On the other hand, 11.6% (95% CI: 6.8%-16.4%) participants developed both nuclear and cortical opacity, 3.5% (95% CI: 0.8%-6.2%) nuclear and posterior subcapsular opacity; and 1.7% (95% CI: 0%-3.6%) cortical and posterior subcapsular opacity. A total of 3.5% (95% CI: 0.8%-6.2%) of participants developed all three types of cataract. Nuclear cataract was significantly associated with current smoking (P = 0.04; relative risk [RR]: 2.05; 95% CI: 1.05-3.99). Males were almost half as likely (P = 0.04; RR: 0.57; 95% CI: 0.34-0.97) to develop cortical opacity, whereas participants with a history of diabetes were approximately twice as likely to develop cortical opacity (P = 0.05; RR 2.43; 95% CI: 1.02-5.81). A higher level of education (P = 0.03; RR: 0.40; 95% CI: 0.18-0.91) and a higher body mass index (P = 0.02; RR: 0.28; 95% CI: 0.10-0.79) was protective of posterior subcapsular cataract. CONCLUSIONS This study indicated a high incidence of cortical opacities and lower incidence of nuclear opacities compared with Caucasians. Posterior subcapsular opacity incidence and cataract surgery rate were comparable.

Impact of Socioeconomic Status on the Diagnosis of Primary Open-Angle Glaucoma and Primary Angle Closure Glaucoma: A Nationwide Population-Based Study in Taiwan

Purpose To understand the impact of socioeconomic status (SES) on the diagnosis of primary open-angle glaucoma (POAG) and primary angle closure glaucoma (PACG) in Taiwan. Methods Subjects with glaucoma were identified from the National Health Insurance Research Database of year 2006, which included one million randomly selected insurants. Individuals who had ≥4 ambulatory visits within one year which had the diagnosis code of POAG (ICD-9-CM 365.11 or 365.12) or PACG (365.23) and concurrent prescription of anti-glaucoma medication or surgery were selected. Individual SES was represented by monthly income calculated from the insurance premium. Neighborhood SES was defined based on neighborhood household income averages. Urbanization level of habitation was categorized into 3 levels. The odds ratio of having POAG or PACG in subjects with different SES was evaluated by using multiple logistic regression analysis. Results In total, 752 and 561 subjects with POAG and PACG, respectively, who were treated on a regular basis, were identified. The diagnosis of glaucoma was affected by age, gender, frequency of healthcare utilization, individual SES, and urbanization level of habitation. With the adjustment of age, gender, healthcare utilization, neighborhood SES and level of urbanization, subjects with lower income were more likely to be diagnosed as PACG, but less likely as POAG. Conclusions Subjects with more frequent healthcare utilization were more likely to be diagnosed with glaucoma. Subjects with low SES were more susceptible to PACG, but subjects with high SES were more likely to be diagnosed as POAG. This information is useful for the design and target participant setting in glaucoma education and screening campaign to maximize the efficacy of limited resources in preventing glaucoma blindness.

Bilateral endogenous Candida endophthalmitis as the presenting manifestation of diabetes mellitus.

Bilateral endogenous Candida endophthalmitis as the presenting manifestation of diabetes mellitus

Effects of Phacoemulsification and Intraocular Lens Implantation on the Corneal Endothelium in Primary Angle-closure Glaucoma

Background Phacoemulsification and intraocular lens implantation (P-IOL) is an option for intraocular pressure (IOP) control for primary angle-closure glaucoma (PACG). This study examined the effects of P-IOL on the corneal endothelium in eyes with PACG. Patients and Methods Ultrasound biometry and pachymetry, as well as specular microscopy, were performed preoperatively and 3 months after surgery in 24 eyes with PACG that underwent P-IOL. The postoperative changes in central corneal endothelial density and central corneal thickness (CCT) were evaluated. The correlations between postoperative endothelial changes and both preoperative IOP control and biometric features were analyzed. Results After surgery, corneal endothelial cell density decreased significantly (p 0.001), with a mean cell loss of 15.7%, and mean CCT increased by 7 μm (p = 0.034). A greater postoperative corneal endothelial loss was correlated with a higher preoperative mean IOP and more glaucoma medications (correlation coefficients=0.487 and 0.427, p = 0.016 and 0.038, respectively). The corneal endothelial changes did not correlate with preoperative biometric features including anterior chamber depth, lens thickness, and axial length. Conclusion Significant corneal endothelial cell loss after P-IOL in PACG patients suggests that corneal endothelium status should be carefully evaluated before performing this surgery in these patients, especially those with poor preoperative IOP control.