The binocular videorefractoscope for visual screening in infancy.
Photorefraction is a promising technique for screening infants for amblyopiogenic defects, but currently used instruments often produce images that are difficult to interpret due to inaccurate control of the subject's fixation, to the narrow range (+/- 4 D) of the measurable error, to ill-defined crescent borders, and to chromatic aberration. A charge-coupled device (CCD) camera with near-infrared sensitivity connected to a computer with an image grabber for real-time equalization was devised to overcome the aforementioned problems. This binocular videorefractoscope (VRB) enables a dynamic and nondissociating refractive status and an ocular motility testing. Fixation and accommodative response are observed on-line and the strabismic angle is measured off-line. Arrays of infrared-emitting diodes with a variable eccentricity and position reveal sphere and/or cylinder errors (+/- 10 D; null interval, +0.00 to -2 in an 8-mm pupil diameter) as well as squint (> 5 prism diopters) and dioptric media opacities. The VRB was tested during noncycloplegic screening for amblyopiogenic defects in 212 3-year-old children. The findings were compared with the results of manifest and cycloplegic autorefractometry in a blind study. The VRB revealed a sensitivity of 81% and a specificity of 97%. In conclusion, the VRB can give a fast, noninvasive, and reliable evaluation of amblyopiogenic factors in infants.
Angi
M R
MR
Clinica Oculistica Università di Padova, Italy.
Bergamo
L
L
Bisantis
C
C
D000065:Accommodation, Ocular; D000293:Adolescent; D000328:Adult; D000550:Amblyopia / Q000517:prevention & control*; D002138:Calibration; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D009885:Ophthalmology / Q000295:instrumentation*; D012029:Refraction, Ocular; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012984:Software; D015351:Vision Screening / Q000379:methods*