Gonioscopic findings associated with a positive dark-room provocative test in narrow angles after laser iridotomy.

PURPOSE: To determine clinical factors and ultrasound biomicroscopic (UBM) findings associated with a positive prone dark-room provocative test (DRPT) in patients with narrow angles after laser peripheral iridotomy (LPI). PATIENTS AND METHODS: Seventeen eyes with a positive DRPT and 18 eyes with a negative DRPT were included in this comparative case series, based on chart review of patients diagnosed with narrow angles persisting after LPI who had undergone clinical evaluation with a 45-minute DRPT and UBM imaging. Subjects with a positive DRPT [an increase of intraocular pressure (IOP) of 6 mm Hg or more] were compared with a negative DRPT control group. Charts were reviewed for age, refraction and gonioscopic examination. UBM measurements obtained included the anterior chamber depth, angle opening distance at 500 µm, angle recess area, anterior chamber angle, trabecular-ciliary process distance, iris thickness, iris-ciliary process distance, height of plateau, and distance of iris-cornea contact. RESULTS: Mean increase in IOP was 11.1±3.5 mm Hg in the positive DRPT group (group A) and 0.9±0.1 mm Hg in the negative DRPT (group B). On indentation gonioscopy, patients in group A had significantly more synechial angle closure of 180 degrees or more (35% vs. 0%, P=0.008), more frequent double-hump sign (59% vs. 11%, P=0.005), and significantly more patients in this group had at least one of these findings, (13/16 vs. 2/15, P=<0.001). Mean age did not differ between groups (P=0.88). There were significantly more women in group B (58% men in group A and 83% women in group B, P=0.01). Mean refraction was +3.41±2.27 D in group A and +2.60±2.06 D in group B (P=0.32). There were no statistically significant differences in any of the UBM parameters between the 2 groups. CONCLUSIONS: A positive DRPT was found in patients presenting a more compromised drainage angle after LPI, due to anterior synechiae and/or an anteriorly positioned ciliary body as shown by the presence of a double-hump sign. DRPT may help identify patients at higher risk of intermittent increases in IOP among those presenting persistent narrow angles after LPI, and indentation gonioscopy remains an important step in evaluating these patients.

Estimation of ocular rigidity in glaucoma using ocular pulse amplitude and pulsatile choroidal blood flow.

PURPOSE: Theoretical models and animal studies have suggested that scleral rigidity plays an important role in the pathogenesis of glaucoma. The aim of this study was to present a noninvasive technique for estimating ocular rigidity (E) in vivo, and to compare the estimated rigidity between patients with open-angle glaucoma (OAG); ocular hypertension (OHT); suspect glaucomatous disc (GS); and normal subjects (N). We hypothesized that OHT patients would have higher rigidity. METHODS: All patients underwent measurements of ocular pulse amplitude (OPA) using dynamic contour tonometry, pulsatile choroidal blood flow (ChBFP) using laser Doppler flowmetry; axial length (AL); and assessment of automated visual field mean deviation (MD). The ratio between OPA and ChBFP was calculated according to the Friedenwald's equation of ocular rigidity. The calculated ratio is denoted as (ER). The average ER values of the four diagnostic groups were compared using nonparametric tests. The relationship between ER and other ocular and systemic factors was examined using correlation and regression analysis. RESULTS: A total of 257 subjects were included in the study (56 N, 108 OAG, 48 GS, and 45 OHT). ER correlated negatively with AL and positively with MD, signifying that a lower rigidity was associated with a longer eye and a worse (more negative) MD. ER was also found to be highest in OHT (0.235 ± 0.16) and lowest in OAG (0.188 ± 0.14; P = 0.01). CONCLUSIONS: Estimated coefficient of ocular rigidity by OPA and ChBFP suggested that glaucoma patients had the lowest rigidity and OHT the highest. It supports the idea that a more compliant ocular shell may predispose the optic nerve head to intraocular pressure (IOP)-related damage.

Savings from the use of a probiotic formula in the prophylaxis of antibiotic-associated diarrhea.

OBJECTIVE: Antibiotic-associated diarrhea (AAD) and particularly Clostridium difficile-associated diarrhea (CDAD) are the most common causes of healthcare associated infectious diarrhea. A double-blind, dose response, placebo-controlled trial of the probiotic formula (Bio-K+ Lactobacillus acidophilus CL1285 and Lactobacillus casei LBC80R formula) for prophylaxis of AAD and CDAD was published in 2010. The Bio-K+ Lactobacillus acidophilus CL1285 and Lactobacillus casei LBC80R formula is a registered trademark of Bio-K Plus International Inc. (Laval, Québec, Canada). Results indicated that the incidence of AAD and CDAD were lower for patients assigned to the probiotic formula compared with the placebo option. The present study aims to estimate the savings in direct medical costs that might result from the use of two different doses of the probiotic formula vs placebo. METHODS: A cost-consequence analysis was conducted to compare the two doses of the probiotic formula compared to placebo. The analysis was based upon published data and adjusted to the North American context. RESULTS: Economic analyses showed that the use of the probiotic formula would result in estimated mean per patients savings of US$1968 for the single dose and US$2661 for the double dose compared with the placebo option if used an average of 13 days by all patients at risk of developing AAD and CDAD. LIMITATIONS: Several key parameters considered within the economic model were not captured within the Gao et al. study. Numerous sensitivity analyses were conducted to address this issue. CONCLUSION: The use of the probiotic formula in prophylaxis of AAD and CDAD would lead to estimated savings in direct medical costs that would substantially offset its acquisition cost. Treating 1000 hospitalized patients on antibiotics with the double dose of the product compared to current practice would save a single payer system the sum of $2,661,218.

Screening for glaucoma with Moorfields regression analysis and glaucoma probability score in confocal scanning laser ophthalmoscopy.

OBJECTIVE: To compare the validity of Moorfields regression analysis (MRA) and glaucoma probability score (GPS) of the confocal scanning laser ophthalmoscopy (Heidelberg retina tomograph 3; HRT3) in detecting glaucomatous optic nerve damage in a screening population. DESIGN: Population-based, cross-sectional study. PARTICIPANTS: Subjects at high risk for development of open-angle glaucoma (OAG). METHODS: All subjects underwent confocal scanning ophthalmoscopy (Heidelberg retina tomograph; HRTII) testing, visual fields testing with frequency-doubling technology perimetry (FDT), and a standard ophthalmologic examination. All HRTII images were reprocessed with HRT3. Based on an ophthalmologic examination and FDT results, eyes were classified into 4 categories: normal, possible glaucoma, probable glaucoma, and definitive glaucoma. Main outcome measures included sensitivity and specificity of HRTII/MRA, HRT3/MRA, HRT3/GPS, and combination HRT3/MRA/GPS. RESULTS: The left eyes of 221 of 291 subjects were included; 4 (1.8%) eyes were classified as definitively having glaucoma. Depending on the reference standard diagnosis as well as on the borderline test-positive definition of the HRTII-3, sensitivity and specificity varied between 36.4% and 100%. For HRTII/MRA, 88.2% to 96.5%, 54.5% to 100%, and 74.5% to 93.6%; for HRT3/MRA, 61.9% to 100% and 64.3% to 85.2%; for HRT3/GPS, 85.7% to 100%; and for combination HRT3/MRA/GPS, 73.4% to 78.2%. CONCLUSIONS: In this pilot study, the MRA of the HRT3 appears to be more sensitive but less specific than the MRA in the HRTII version. The GPS, although somewhat less specific than MRA (and some discs are nonclassifiable by this technique), had greater sensitivity and as a screening method may have the additional advantage of being contour-line independent.

Combining rim area to disc area asymmetry ratio and Moorfields regression analysis of confocal scanning laser ophthalmoscopy for glaucoma screening.

OBJECTIVE: To determine the utility of combining rim area to disc area asymmetry ratio (RADAAR) and Moorfields regression analysis (MRA) to detect primary open-angle glaucoma (POAG) using confocal scanning laser ophthalmoscopy (CSLO) (Heidelberg retina tomograph 3 (HRT3)) in high-risk populations. DESIGN: Cross-sectional study. PARTICIPANTS: Subjects with high risk for developing POAG. METHODS: Subjects underwent HRT, frequency doubling technology perimetry (FDT), and complete ophthalmic examination. Based on an ophthalmologic examination and FDT results of the worse eye, subjects were classified into 4 categories: normal, possible glaucoma, probable glaucoma, and definite glaucoma. Main outcome measures included sensitivities (Se), specificities (Sp), positive and negative predictive values (PPV, NPV), and positive and negative likelihood ratios (PLR, NLR) of the MRA, RADAAR, and combined MRA- RADAAR tests. RESULTS: Of 375 subjects, 11 were classified as having definite glaucoma. Depending on the reference standard, range results for Se, Sp, PPV, NPV, PLR, and NLR were, respectively, 57.7% to 100%; 55.1% to 85.4%; 6.3% to 39%; 92.6% to 100%; 1.97 to 4.9; 0 to 0.49 for MRA; 11.5% to 27.3%; 98.1% to 98.8%; 30% to 60%; 87.4% to 97.8%; 9.29 to 14.1; and 0.74 to 0.89 for RADAAR; and 57.7% to 90.9%; 81.3% to 85.1%; 12.8% to 38.5%; 92.6% to 99.7%; 3.87 to 4.85; 0.11 to 0.50 for combination MRA-RADAAR. DISCUSSION: When using HRT in populations at high risk for glaucoma, RADAAR had a higher specificity than MRA in identifying glaucoma. When patients were classified as borderline on MRA, combining RADAAR values decreased the number of false-positives as well, and may be recommended when high specificity is required.

The validity of screening for open-angle glaucoma in high-risk populations with single-test screening mode frequency doubling technology perimetry (FDT).

PURPOSE: To evaluate whether a single frequency doubling perimetry (FDT) test is a valid screening tool to detect open-angle glaucoma (OAG) in high-risk populations. PATIENTS AND METHODS: All participants underwent frequency doubling Technology perimetry (FDT C-20-5 algorithm, Carl Zeiss Meditec Inc, Dublin, CA) and complete ophthalmic examination. FDT printouts were classified according to Iwasaki and Patel protocols. Gold-standard was clinical diagnosis of glaucomatous optic nerve damage. MAIN OUTCOME MEASURES: Sensitivity, specificity, positive predictive value, negative predictive value, positive, and negative likelihood ratios of a single-test screening FDT. RESULTS: Data of 445 right eyes and 408 left eyes of participants were analyzed. On the basis of clinical diagnosis, 19 right eyes (4.3%) and 20 left eyes (4.9%) had glaucoma. Depending on the gold standard used, the range of sensitivity was between 40.7% and 78.9%, 66% and 70% for specificity, 7.7% and 25.2% for positive predictive value, 82.3% and 98.6% for negative predictive value, 1.25 and 2.37 for positive likelihood ratio, and 0.32 and 0.87 for negative likelihood ratio. The κ coefficient of agreement between the FDT classifications as described by Iwasaki et al and Patel et al was 0.936 in right eyes and 0.935 in left eyes. CONCLUSIONS: The sensitivity and specificity of a single reliable screening FDT test were low. Thus, a single screening FDT test in even a high-risk population has poor validity and steps should be taken to better define the target population before testing, and enhance the FDT screening strategy.

Assessment of factors affecting the difference in intraocular pressure measurements between dynamic contour tonometry and goldmann applanation tonometry.

PURPOSE: To determine if the difference in intraocular pressure (IOP) measurements between dynamic contour tonometry (DCT) and Goldmann applanation tonometry (GAT) is correlated with axial length (AL), and to assess the possible influence of age, sex, central corneal thickness (CCT), corneal hysteresis (CH), ocular pulse amplitude (OPA), and glaucoma status on the difference in IOP measurements between the 2 instruments (ΔIOP=DCTIOP- GATIOP). METHODS: Two hundred sixty-oneparticipants (509 eyes) in these 4 groups were included: 53 normal individuals (N; 106 eyes), 112 glaucoma patients (OAG; 212 eyes), 52 glaucoma suspects (GS; 103 eyes), and 44 patients with ocular hypertension (OHT; 88 eyes). The patients who had had an incisional ocular surgery were excluded. All participants underwent IOP evaluation with DCT and GAT and AL, CCT, and CH measurements. The influence of age, sex, AL, CCT, CH, OPA, and glaucoma diagnostic status on ΔIOP was evaluated using correlation analysis and analysis of variance (ANOVA). Right (OD) and left eyes (OS) were analyzed separately. RESULTS: ΔIOP was higher in eyes with longer axial lengths (OD: r=0.142, P=0.02; OS: r=0.233, P<0.001). ΔIOP also correlated with CH (OD: r=-0. 127, P=0.04; OS: r=-0.169, P=0.01), in which the ΔIOP increased as CH decreased (corresponding to less rigid corneas). OPA also correlated negatively with ΔIOP, but the correlation was only statistically significant in left eye (OD: r=-0.112, P=0.08; OS: r=-0.124, P=0.05). Age, CCT, sex, and diagnostic status did not influence ΔIOP significantly. CONCLUSIONS: GAT underestimated IOP more compared with DCT in patients with longer axial length and in patients with lower corneal hysteresis.

Screening for primary open-angle glaucoma in the developed world: are we there yet?

BACKGROUND: In 1995, the Quebec Agency for Health Services and Technology Assessment (AETMIS) stated that a formal screening program for primary open-angle glaucoma (POAG) could not be recommended for the province of Quebec, owing to "a high degree of uncertainty and because of the high cost such a program would entail." The purpose of this article was to evaluate the possibility of instituting a POAG screening program in light of recent advances in the diagnosis and treatment of glaucoma. METHODS: We reviewed new developments that have occurred since the mid to late 1990s in the field of glaucoma. Changes that could positively influence the feasibility and organization of future glaucoma screening programs were identified. RESULTS: New technologies, including confocal scanning laser ophthalmoscopy (HRT II), optical coherence tomography (Stratus OCT), and scanning laser polarimetry with variable corneal compensation (GDx-VCC), permit early detection of optic nerve and nerve fibre layer structural damage. Together with advanced psychophysical tests (frequency doubling perimetry and short wavelength automated perimetry) for earlier detection of functional damage, they provide an increased understanding of the diagnosis and monitoring of POAG. Elevated intraocular pressure (IOP) remains the most important risk factor for glaucoma. Clinical trials indicate that lowering IOP at different stages of the disease can arrest or decrease its rate of progression. Moreover, it is important to assess pachymetry because IOP measurements are influenced by central corneal thickness. Finally, new treatments, such as prostaglandin analogues or selective laser trabeculoplasty, are safer and may also achieve lower intraocular pressures. INTERPRETATION: Health policy involves the investment of public resources, and cost-effectiveness analyses for POAG screening are heavily weighted by the degree of uncertainty that glaucoma screening can be effectively and reliably achieved. The many new developments and advancements outlined herein, combined with the possible increasing prevalence of POAG, necessitate the re-evaluation of screening for primary open-angle glaucoma.