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Autorefractometer
- 1. Presented by :- Optom-Santosh mangate MGM school of biomedical sciences
- 2. Introduction • The refractometry is an objective method to finding out the error of the refraction. • AR is also called as refractometer , optometr and objective refractometer.
- 4. History • Over the last 200 years or so many attempts have been made to automate process to refraction but with little success. • Until recently, when successful autorefractors were developed Over the 30 years which could objectively determine a patient refractive status with an acceptable level of reability.
- 5. The scheiner Principle • Scheiner discovered in 1619 that the point at which an eye was focused could be precisely determined by placing double pinhole apertures before the pupil. • Parallel Rays of light from a distant object Are reduced to too small bundles of light by the scheirner disc. • These form a single focus on the retina if the eye is emetropic; but if there is any refractive error two spots fall on a retina.
- 9. Fogging • Alle autorefractometers now use the fogging technique to relax accommodation prior to objective refraction. • These is the reason why patients state the target is blurred prior to measurements being taken-these is the effect of the fogging lens.
- 10. 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 Autorefractometers today come with an 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
- 12. Features • The computerised autorefractometer quickly gives information about the refractive error of the patient in form of sphere, cylinder with axis and interpupilary distance. • These method is good alternative to retinoscope in busy practice.
- 13. Indications • Myopia . • Hipermetropia. • Astigmatism . • Presbyopia. • Glass priscription. • Contact lens priscription. • The starting point for optometrist and ophthalmologist .
- 14. • Paediatric refraction • People with disability requiring glasses
- 15. Contraindications • Mentaly disabled patients • Patients with postural problems • Acute troumatic injury to the eye • Artificial prosthesis • Very small children • Patients with accommodation anomalies
- 16. Complications • Poor fixation - the patient blinks excessively and doesn’t fix the primary point • High refractive error - The autorefractors may not be fairly accurate at high refractive errors. • Media opacity -such as pterigium, corneal opacity, cataract • Cost -they are realatively costly equipment comparatively to retinoscopy Instruements.
- 17. Types • Autorefractometer Semi automated Fully automated • Autokeratorefractometer • Portable refractometer
- 19. Use of AR • Estimation of refractive error hipermetropia, myopia , astigmatism. • Vertex distance • Interpupilary distance • Mode can be change as phakic eye, pseudophakic eye and aphakic eye.
- 20. Limitations of AR • Not use for near refraction • Peripheral light rays from the room can affect the readings so dark room is required.
- 21. Problems can face with autorefractometer 1. Alignment problem:- • Improper chin on chin rest • Improper head on head rest • Patients not co-operative - Irregula astigmatism:- • Axis change • Irregular mires due to irregular cornea:- pterizium , keratoconus, corneal opacity Corneal distrophy.
- 22. Question for you ?
- 23. Thanks for attention 😊