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Catherine Howard, Parul Patel, Roger Wong; Validation Of Three Handheld Automated Keratometers Against The Pentacam In Adults. Invest. Ophthalmol. Vis. Sci. 2012;53(14):115.
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© ARVO (1962-2015); The Authors (2016-present)
To compare three handheld keratometers (Nikon Retinomax-2, Nidek ARK-30, and Nidek KM-500) with the Oculus Pentacam keratometer.
18 staff members (36 eyes) age 24-72 were recruited. Prior to involvement in the study, all patients underwent slitlamp review in order to establish normal corneal clarity and structure. In addition, all patients were refracted by an experienced optometrist. No patient had ocular astigmatism of more than ±3.25 DC. Each subject underwent keratometry readings from all four machines on both eyes, although the order in which each machine was used was randomised. For all machines except the Pentacam, 2 measurements were taken for each eye. The same operator (an experienced optometrist) performed all measurements. Each autorefractor was calibrated prior to testing on a daily basis. The same autorefractors were used for all subjects throughout the study.
All three hand-held keratometers demonstrated a statistically significant correlation co-efficient with the Pentacam. In the vertical meridian,The NIDEK ARK-30 correlated most closely with the Pentacam, demonstrating a correlation co-efficient (r) of 0.968 (p<0.01). The NIDEK KM-500 and Nikon Retinomax-2 followed with r= 0.927 (p<0.01) and r=0.915 (p=0.01) respectively. In the horizontal meridian, the Nikon Retinomax-2 correlated most closely with the Pentacam, achieving a correlation co-efficient of 0.986 (p=<0.01). NIDEK ARK-30 measured r=0.977 (p<0.01) and NIDEK KM-500 r=0.969 (p=0.01).
The NIDEK ARK-30, NIDEK KM-500 and Nikon Retinomax-2 hand held portable keratometers compare favorably with the Pentacam. Overall, the NIDEK ARK-30 demonstrated the closest correlation with the keratometry readings provided by the Pentacam. The additional advantage of portability means they should be considered suitable alternatives to the Pentacam in pediatric patients and those with poor mobility.
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