Repeatability of Iop Measurement With the Non-Contact Tonometer

Assessment of reproducibility of measures of intraocular pressure and central corneal thickness in young white adults over a 16‐h time period

“…The present data on the expected ranges of values for NCT measures and the calculated variance (COV) are not inconsistent with those from previous studies (Myers, 1974; Brown and Darin, 1989; Russell et al ., 1989; Myers et al ., 1990; Brencher et al ., 1991; Vernon, 1993; Tuck and Crick, 1994; Mackie et al ., 1996; Cho and Liu, 1997; McCaghrey and Mathews, 2001). While it does not appear to be possible to generate a realistic or reliable average number from the literature, a survey of a range of published articles indicates that the repeatability of NCT, like Goldmann tonometry, is likely to be somewhere between ±1 and ±3 mmHg.…”

The Validity of a New Noncontact Tonometer and Its Comparison with the Goldmann Tonometer

“…11 It also demonstrated greater fluctuations in IOP during consecutive NCT measurements. 12 Therefore, it is recommended that an average be taken from several IOP readings.…”

Multiple applications of the NCT: an assessment of the instrument's effect on IOP

“…The A 0 Non-Contact Tonometer (NCT) reading is not affected by ocular rigidity and does not touch the eye, but nevertheless causes a slight corneal flattening during a measurement. In addition, this instrument has been shown to produce repeatable, accurate readings (Myers, 1974;Wittenberg, 1973;Shields, 1980;Sorensen, 1975). The purpose of this study is to evaluate if the NCT is suitable for tonography by multiple application of the air puff in a quick succession.If the NCT is not an effective instrument for the purpose of tonography, the study is intended to also test the value of averaging multiple IOP measurements.…”

“…Wittenberg (1973) has shown that multiple measures are possible with the instrument on the override setting. His study performed fewer measurements on a smaller group of subjects and was not intended to study the NCT's potential tonographic properties.Our protocol differed significantly from the procedure used by Myers (1974) who executed a series of 25 readings per eye over a 22 minute period. In addition to the longer measurement period, Myers alternated the recordings between right and left eye: first five readings on the right eye followed by five readings on the left eye in a 2-minute run followed by a 3-minute subject rest.…”