L Ventura et al 2006 Phys. Med. Biol. 51 3085 doi:10.1088/0031-9155/51/12/006
L Ventura1,2, C Riul1,3, S J F Sousa2, J G S De Groote1, A B Rosa Filho1 and G C D Oliveira1
Show affiliationsWe have developed an automatic keratometer module for slit lamps that provides automatic measurements of the radii of the corneal curvature. The system projects 72 light spots displayed in a precise circle at the examined cornea. The displacement and deformation of the reflected image of these light spots are analysed providing the keratometry. Measurements in the range of 26.8–75 D can be obtained and a self-calibration system has been specially designed in order to keep the system calibrated. Infrared LEDs indicate automatically which eye is being examined. Volunteer patients (492) have been submitted to the system and the results show that our system has a high correlation factor with the commercially available manual keratometers and the keratometry measurements from a topographer. Our developed system is 95% in agreement with the corneal topographer (Humphrey—Atlas 995 CZM) and the manual keratometer (Topcon OM-4). The system's nominal precision is 0.05 mm for the radii of curvature and 1° for the associated axis.
Instrumentation and measurement
Issue 12 (21 June 2006)
Received 14 February 2006, in final form 8 March 2006
Published 31 May 2006
L Ventura et al 2006 Phys. Med. Biol. 51 3085
A. S. Evans et al. 2002 ApJ 580 749
Yukiyasu Ozeki 1996 J. Phys. A: Math. Gen. 29 5805
T. R. Hunter et al. 2006 ApJ 649 888
D Wilkinson and J F Willemsen 1983 J. Phys. A: Math. Gen. 16 3365
A Olivo and R Speller 2006 Phys. Med. Biol. 51 3015
S D Bartlett et al 2002 J. Phys. A: Math. Gen. 35 5599
C Lewiner and G Bastard 1978 J. Phys. C: Solid State Phys. 11 4727
David Sudarsky et al. 2005 ApJ 627 520
A Bianconi et al 2000 J. Phys.: Condens. Matter 12 10655