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Richard Chitedze, Vincent Saka, Joseph Msosa, Stephen Cook, Elly Chemey, William E Sponsel; Association of Icare and Applanation Tonometry in a Central African Population. Invest. Ophthalmol. Vis. Sci. 2018;59(9):2701. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Handheld rebound tonometry, which requires no topical anaesthetic, maintenance, calibration or regular service could be ideally suited to screening programs in rural Africa if accurate measurement can be obtained in such individuals. This study compares IOP values obtained with Icare rebound tonometry versus concomitant Perkins applanation among an evenly distributed population of normotensive and ocular hypertensive subjects.
This study was carried out at the Eyes of Africa Clinic at Child Legacy Hospital in Msundwe, Malawi under the auspices of the Malawi Ministry of Health. All tenets of the Declaration of Helsinki were adhered to in this Ministry approved prospective study. Applanation measurements were obtained from both eyes in random sequence using the Icare TAO1i (Icare, Finland) and Perkins applanation (Clement Clarke, UK) handheld tonometers. Mean measurements of 2 masked clinicians (RC&VS) applying standard methodology (including benoxinate fluorescein for applanation) were used. To avoid the typical biasing effect of lower-IOP preponderance on the resulting correlation a maximum of 10 randomly selected measurements per IOP range (0-5,6-10,11-15…46-50) were used to determine the linear association between the two tonometers across a broad IOP range. Patient and clinician preference was also assessed.
280 IOP measurements were obtained (140 adults, 78F/62M, mean 55.5yrs). These included 35 hypertensive measurements (22-50mmHg) with either instrument, all of which were evaluated together with 48 evenly distributed but randomly selected IOP pairs from among the remainder (total analysis n=83).A very strong linear correlation (see Figure) was observed between the two tonometers across a wide IOP range (R=0.90, R2=0.81; P<0.00001). All eyes generating an IOP>21mmHg by applanation also provided an IOP >21mmHg with the Icare, which was systematically confirmed to be easier and quicker to use, and preferred by patients.
Portable Icare rebound tonometery provided IOP values very consistent with those obtained by applanation, and very reliably detected ocular hypertension. It appears ideally suited for use in clinical and rural outreach screening settings in Central Africa.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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