Positive correlation between Tono-pen intraocular pressure and central corneal thickness
Section snippets
Methods
A prospective study was conducted at four public buildings (3 malls, 1 hospital) between 9 am and 4 pm as part of an eye health information and glaucoma-screening program. Participation was strictly voluntary, and all individuals who were willing to be tested were included. Initially, each participant filled out an anonymous questionnaire that asked for information pertaining to possible risk factors and exclusion criteria (Fig 1).
Subjects were then given topical anesthesia (Alcaine; Alcon, Ft.
Results
A total of 351 subjects were tested in the screening protocol. Subjects were excluded from the study if they were diagnosed with glaucoma (n = 7), were wearing contact lenses (n = 7), had no CCT or IOP measurements for both eyes (n = 3), had prior eye trauma (n = 1), or had pseudophakos (n = 1). In total, 19 of 351 subjects were excluded completely from the study. Of the remaining 332 subjects, 651 eyes were included in the study. Some eyes (5 right and 8 left) were excluded because prior
Discussion
Previous investigators have reported on the relationship between CCT and measured IOP for Goldmann applanation tonometry.1, 2, 3, 4, 10, 11 The Goldmann tonometer has been calibrated for a CCT of approximately 0.52 mm and will tend to overestimate IOP in structurally thicker corneas and underestimate IOP in thinner corneas. In corneas with a CCT greater than 0.52 mm, this systematic error in IOP measurement is related to more corneal rigidity due to the increased CCT. This increase in rigidity
Acknowledgements
The authors thank Mentor Canada for supplying the Tono-Pens used in this study.
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C3 Transferase-Expressing scAAV2 Transduces Ocular Anterior Segment Tissues and Lowers Intraocular Pressure in Mouse and Monkey
2020, Molecular Therapy Methods and Clinical DevelopmentCitation Excerpt :Accordingly, corneal edema and thickening were observed in the scAAV2-C3-injected eyes after 7 days, and a quadratic relationship was found between the results of measured IOP and the grade of edema or CCT. The TonoVet tonometer uses rebound tonometry to measure IOP,52 and there was a significant influence of corneal thickness on this type of tonometer.53,54 Our results agree with these findings and showed a significantly positive association found between the CCT and measured IOP when the CCT ratio exceeds a value of 1.6 (Figure 4F).
Central Corneal Thickness and its Associations With Ocular and Systemic Factors in an Urban West African Population
2016, American Journal of OphthalmologyCitation Excerpt :Thinner mean CCT measurements have been reported in African-American persons than in white individuals inclinic-based studies in North America7,21–24 and in population-based studies on Afro-Caribbean persons in Barbados.9 In our study, the mean ± SD of CCT was 533.9 ± 34.0 μm, which is in keeping with the CCT measurements of African Americans and Afro-Caribbeans in earlier studies (range 518.0–531.0 μm).7,22–24 In another study characterizing the corneal thickness of African persons within the African continent itself, Mercieca and associates reported that the mean CCT of 70 patients recruited from a glaucoma clinic in Nigeria was 532.0 μm, which was very similar to our population-based data.10
Numerical study on human cornea and modified multiparametric correction equation for Goldmann applanation tonometer
2014, Journal of the Mechanical Behavior of Biomedical MaterialsCentral corneal thickness does not correlate with TonoLab-measured IOP in several mouse strains with single transgenic mutations of matricellular proteins
2013, Experimental Eye ResearchCitation Excerpt :Prior to the development of rebound tonometry (RT), other techniques to measure IOP were used such as microneedle catheterization of the eye (John et al., 1997) and a modified Goldman applanation tonometry (GAT), which involves the reduction of biprism angles in the instruments applanating tips, was the most widely used and closely studied method for IOP measurement in mice (Cohan and Bohr, 2001; Kim et al., 2007). However, GAT is highly operator dependent and has an observed decline in IOP readings with repeated measurements as is often performed in research studies (Dohadwala et al., 1998). Based on the induction-impact model, rebound tonometry (RT) rapidly bounces a magnetized probe off of the central cornea and analyzes the return motion with a sensing coil (Danias et al., 2003).
Evaluation of trabecular meshwork-specific promoters in vitro and in vivo using scAAV2 vectors expressing C3 transferase
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