AUTOREFRACTOMETER

1. AUTOREFRACTOMETER
ASKAR.PK

2. lntroduction
• The refractometry is an objective method to finding out the
error of the refraction
•
• A R is also called as refractometer, optometer and objective
refractometer.

4. History
• Over the last 200 years or so many attempts have been made toautomate
process to refraction but with little success.
• Recently. when successful autorefractors weredevelopedoverthe30
yearswhichcould objectively determine apatient refractive status with
an acceptable level of reliability

13. FIXATION TARGET:-
• A variety of targets have been used
for fixation ranging from animations to
pictures with peripheral blur to further
relax accommodation.
• Accommodation is most relaxed when
the patient identifies the scene as one
typically seen at a distance which can
be achieved by using visual fixation
targets composed of photographs or
animations of outdoor scenes.

14. Fogging
• Autorefractometers are now use the fogging technique to relax
accommodation prior to objective refraction.
• This is the reason why patients state the target 1s blurred prior
to measurements being taken-this is the effect of be fogging
lens.
•

15. Autorefractometers currently in use
• Autorefractometers are most commonly used to provide the
starting point of refraction to obtain an objective result before
performing subjective refraction.
Most commercially available Autoreftactometers today come with
inbuilt Automated keratometer are known as Auto kerato-
refractometer..
• Recently new equipments with additional corneal topographers
have been developed in which corneal topography can also be
performed.
•

17. Features
• The computerised autorefractometer quickly gives
information about the refractive error of the patient in form
of sphere,cylinder with axis and interpupilaiy distance.
• These method is good alternative to retinoscope in busy
practice.

18. Indications• The starting point for optometrist
and ophthalmologist .
• Paediatric refraction
• People with disability requiring
glasses
• Myopia .
• Hypermetropia.
•Astigmatism .
•Presbyopia.
• Glass prescription.
• Contact lens prescription
“

19. Contraindications
•Mentaly disabled patients
•Patients with postural problems
•Acute traumatic injury to the eye
•Artificial prosthesis
•Very small children
•Patients with accommodation anomalies

20. Complications
• Poor fixation
• The patient bIinks excessively and doesn't fix the primary
point
• High refractive error-The autorefractors may not be fairly
accurate at high refractive errors.
• Media opacity- suchas Pterygium, Corneal opacity, Cataract
• Cost- They are relatively costly equipment comparatively to
retinoscopy Instruments.

21. Types
•Autorefractometer
-Semi automated
-Fully automated
• Autokeratorefractometer
• Portable refractometer

23. Use of AR
• Estimation of refractive error hypermetropia,myopia ,
astigmatism.
• Vertex distance
• Interpupilary Distance
-Mode can be change as phakic eye, pseudophakic eye and
aphakic eye.

24. Limitations of AR
• Not use for near refraction
• Peripheral light from the room can affect the reading.So dark
room is required

25. Problems can face with autorefractometer
• Alignment problem
• Improper chin or chin resr
• Improper head or head rest
• Patient not co-operative
• Irregular astIgmarism:-
• Axis change
• Irregular mires due to irregular cornea