High Quality Eyewear Accessories Optical Instrument Optometry Resin Prism Bar Ophthalmic Set Retinoscopy Rack Flipper Functional principle : The vision card is designed according to the minimum visual angle that can be distinguished by the human eye within the reading distance.Combined with the flipper for accommodation facility training.Adjust the pupil distance according to the needs of different trainers. Applicable population : It is mainly used in the treatment of myopia patients with low accommodation capability,accommodation lag and insufficient accommodation facility. Pupil distance range : 40-80mm The available degrees : ±0.50/±1.00/±1.50/±2.00/±2.50/±3.00