Phoropter; it’s definition, meaning and specifications

Phoropter; definition and explanation

1. Phoropter Md . Nooruz Zaman M.Optom Faculty and consultant optometrist Sankara College of Optometry

2. Phoropter is an instrument designed to provide convenient way of placing trial lenses in front of patient to measure refractive state of eye. Principle: To determine the refractive status of the eye and refractive correction

3. Manual Refractors: Reichert Refractors Topcon Refractors Macro Refractors Bausch & Lomb Refractors Automatic Refractors: Tomey TAP 1000 Digital Refractor Huvitz CDR-3100 Types

4. Basic Model of Refractors Parameters are adjusted using knobs and dials. Manual Refractors

5. Both monocular and binocular PD is adjusted using knobs on the top of the instrument. 48 to 75mm by 1mm step Pupillary Distance

6. Rotating the wheel or by tuning the knob. Rotating the downward for plus power and upward for minus power. Range of power: 0 to –19.00D in 0.25D step (0.12D step) 0 to +16.75D in 0.25D step (0.12D step) Spherical power

7. Power and axis is accompanied by turning the knobs. Changing Power by small centre knob and axis by rotating. B&L green type refractor, small knob for axis and larger one for the power available in plus or minus cylinder models. 0° a 180° ( Increments : 1° , 5° , 15° ) 0 to –6.00D (-8.00D) in 0.25D step (0.12D step). Cylinderical power

8. Refining cylindrical power and axis. Equal powers with opposite sign in the two principal meridians. Knurled knob to flip the lens ± 0.25D (± 0.37D and ± 0.50D as option) Cross Cylinder

9. Risley prism / Rotatory prism Used for measuring phorias and fusional vergence 20 ∆D in 1 prism steps. Prism

10. "0/0": Open Aperture "R": Retinoscopic Lens: +1.50D standard +2.00D option "P": Polarizing Filter "WMV/RMV": Maddox Rod, vertical: white(left) red (right) WMH/RMH": Maddox Rod, horizontal: white(left) red (right) +/-12 Strong spherical power "GL": Green Lens (left) "RL": Red Lens (right ) "PH": Pin hole "10 L": 10 Diopter Prism Base In (Left) "6 U": 6 Diopter Prism Base Up (Right) "+_ 50": +_0.50D Fixed Cross Cylinder "OC": Occluder Auxiliary lenses

11. Automated Phoropter

12. Two disc like castings that house the lenses Instrument is mounted on a pole or stand A forehead rest is present to ensure that the patient is correctly positioned. Large central knob – to adjust the interpupilary distance Body of phoropter

13. Sphere and cylinder lenses on three disc Disc closest to eye – high power sphere Second disc - low power sphere Third disc - cylindrical lenses The axis is marked on the front surface are in degrees 0 to 180 degrees with axis marking in 5 degrees Contd..

14. Occluders Maddox rods + 1.50D lens for retinoscopy Pinholes Prisms Reading card holder is also attached to front of the phoropter . Contd …

15. Amplitude of accommodation Relative accommodation Fusional vergence Various Binocular Balancing Test Other Tests

16. Useful data-link among mirror chart, projector, refractor & lensmeter . Automatic data transmission & integrated management of customer´s data. Refractometer´s data and lensmeter´s data can be shared. Built-in printer in the Operation Panel . More test at less time.

17. Parameters

18. Less Time consuming More comfortable. No scratches or dust on the lenses. Additive errors can be reduced. Convenient way of Changing lenses and accessories Same instrument for child . Special test can be carried out with the same instrument. Axis of cylindrical correction can be read off from the refractor head with greater accuracy. Advantages

19. It hide the patients face Difficult to observe Head posture and eye position, Difficult to do cover test Off axis cylindrical correction, in patients with head tilt. Children below 4 yrs/ special child/ elderly people. Frequent calibration is required. Expensive Disadvantages