PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 9866522

Tonometry.

W L Ottar
View original source ↗Export metadata ↓

Abstract

Tonometry is the measure of intraocular pressure. There are several methods used to obtain intraocular pressure, such as Goldmann applanation tonometry, Tono-Pen tonometry, pneumotonometry, and tactile tension. All these methods have advantages and disadvantages. Measurement of intraocular pressure plays an important role in the detection and management of glaucomatous conditions. It is important that the examiner be aware of the various methods and their shortcomings to obtain the most accurate measurement. By obtaining the most accurate intraocular pressure by tonometry, the diagnosis and management of glaucoma can be enhanced.

Explore related subjects

BiasGlaucomaHumansInfection ControlTonometry, OcularJournal ArticleReview

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

W L Ottar. 1998. Tonometry.. https://doi.org/10.1016/s1060-135x(98)90004-5

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2026

Assessment of blinding in pharmacotherapy and noninvasive neuromodulation randomized controlled trials for neuropathic pain in adults.

In randomized controlled trials (RCTs), study participants and research personnel are often blinded to minimize biases related to knowing treatment allocation. To determine if blinding was effective, participants may be asked which treatment they believe they received ("treatment guess"). This descriptive review characterized blinding assessment (BA) reporting in pharmacotherapy and neuromodulation neuropathic pain RCTs. Of 288 papers, 36 (12.5%) reported a BA. One paper reported the results of 2 studies, so in total 37 studies with a BA were assessed. Of these, 19 were crossover, 17 parallel, and 1 partial crossover in design. All 37 studies assessed participant blinding, and 10 also assessed investigator blinding. Approximately 27% included an "unsure" answer option for treatment guess, and 38% asked the reason for the guess. There were no clear patterns in BA reporting across time nor based on treatment type. Seventeen trials provided sufficient data to calculate Bang Blinding Index (BI) to determine blinding success. Participants remained blinded (BI = 0 &#xb1; 0.2) in 10/17 placebo and 10/17 treatment arms, 6 placebo and 5 treatment arms had a BI > 0.2 suggesting possible unblinding, whereas 1 placebo and 2 treatment arms had a BI < -0.2 suggesting misinformed guessing. Overall, we found that BAs are done in a minority of published neuropathic pain trials and with variable methodology. Given the importance of minimizing risk of bias because of treatment unblinding, future studies should consider including BAs, and further consensus building is necessary to determine if and how BAs should be conducted and interpreted in analgesic clinical trials.

Bias↗
PubMed2003

Choice of test for comparing two groups, with particular application to skewed outcomes.

We consider a clinical trial where a skewed outcome variable is to be compared between two groups. While comparison of sample means may lack power, we show that power also depends on the nature of the anticipated treatment effect. For any given distribution in the control arm, there is a family of true distributions in the intervention arm for which the most powerful test is a comparison of arithmetic means. Similar results hold for a comparison of geometric means, and approximately for the Wilcoxon rank sum test and a comparison of medians. We discuss how these methods could be used in planning the analysis of a clinical trial in which the intervention effect alters the shape of the distribution. These ideas are illustrated by a trial in community psychiatry, where the primary outcome (days in hospital) was highly skewed but the intervention was mainly expected to reduce the frequency of values in the tail. We show that a comparison of sample means is a reasonable choice in this case despite the skewness.

Bias↗
PubMed2003

Fidelity and enhanced sensitivity of differential transcription profiles following linear amplification of nanogram amounts of endothelial mRNA.

Although mRNA amplification is necessary for microarray analyses from limited amounts of cells and tissues, the accuracy of transcription profiles following amplification has not been well characterized. We tested the fidelity of differential gene expression following linear amplification by T7-mediated transcription in a well-established in vitro model of cytokine [tumor necrosis factor alpha (TNFalpha)]-stimulated human endothelial cells using filter arrays of 13,824 human cDNAs. Transcriptional profiles generated from amplified antisense RNA (aRNA) (from 100 ng total RNA, approximately 1 ng mRNA) were compared with profiles generated from unamplified RNA originating from the same homogeneous pool. Amplification accurately identified TNFalpha-induced differential expression in 94% of the genes detected using unamplified samples. Furthermore, an additional 1,150 genes were identified as putatively differentially expressed using amplified RNA which remained undetected using unamplified RNA. Of genes sampled from this set, 67% were validated by quantitative real-time PCR as truly differentially expressed. Thus, in addition to demonstrating fidelity in gene expression relative to unamplified samples, linear amplification results in improved sensitivity of detection and enhances the discovery potential of high-throughput screening by microarrays.

Bias↗