Table 4.

Overview of recent studies comparing the repeatability and reproducibility of different instruments for measuring CCT, ECD and CV

Author (year)	Instruments and parameters compared		Sample size	Age range	Clinical condition	Agreement between results?
	CCT	ECD/CV
Cheung et al. (2000)[29]		SP-2000P vs. IMAGEnet®	1.) 8 eyes to evaluate SP-2000P performance	20–29	Some subjects were contact lens wearers	No*
			2.) 7 eyes to evaluate reproducibility
			3.) 12 eyes to evaluate repeatability
O’Donnell et al. (2004)[28]		SP1000P vs. CS3	50 eyes	21–42	Neonates and contact lens wearers	No*
Uçakhan et al. (2007)[26]	USP vs. SP-2000P		45 eyes**/62 eyes†	13–52	Mild myopia and keratoconics	No*
Brugin et al. (2007)[32]	USP vs. z-ring CS4		44 eyes	22–49	22 eyes were post refractive surgery	No*

*In all studies the variation between instruments was statistically significant.

**Mild myopia (minus 1–6 dioptres).

†Patients with keratoconus.