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An auto-refractor or optometer is an instrument that helps in the automated assessment of refraction. This is an alternative method of finding out the refraction error in contrast to the conventional refractive technique. The procedure is called refractometry or optometry. The auto-refractors can be of various types depending on the underlying principle. The various indications of performing optometry are myopia, hyperopia, astigmatism, presbyopia, spectacle prescription, and contact lens prescription, which serve as a starting point for subjective refraction for ophthalmologists and optometrists in pediatric refraction and people with a disability requiring spectacles. This activity covers the various commercially available subjective and objective auto-refractors and provides information for healthcare providers who work with ocular disorders that auto-refractors can address. Objectives: Review the indications of the auto-refractor. Summarize how an auto-refractor functions and the types of auto-refractors. Outline the clinical significance of auto-refractor. Explain the interfering factors in auto-refractor. Access free multiple choice questions on this topic.

Manual refraction is the commonly performed optical investigation to understand the errors of refraction, and the procedure has been widely developed.[1] The retinoscopic procedure is time-consuming, subjective, and may not yield accurate results consistently. Not all optometrists or ophthalmologists can accomplish it accurately.[2] The alternative to this refractometry. Refractometry or optometry is assessing refractive error with a refractometer or optometer instrument. Automated refractors or autorefractors are instruments designed to assess the refractive error and can vary based on the underlying principle.[3] The last 200 years were focused on automating the process of refraction, but little success was achieved. The last few years have noticed the advent of successful autorefractors, and in the last 30 years, autorefractors have been manufactured which can objectively assess the patient's refractive status with a good level of reliability.[4] As technology has improved, autorefractors have become reliable and sophisticated, and recently published literature has labeled them more reliable, repeatable, and accurate than subjective retinoscopy. Autorefractors were initially designed by NASA to assess the vision of the pilots. The growing popularity of these devices is due to increased speed, repeatability, accuracy, and repeatability.[5] In high-volume tertiary eye care setups, autorefractors offer the speed and accuracy for patient assessment in a short period.[6] The autorefractors are based on Scheiner's principle and the optometer principle.[7] The development of autorefractors can be grouped as early autorefractors and modern autorefractors. The early subjective autorefractors are the Badal optometer and Young's optometer. The early objective autorefractors are based on the optometer principle.[8] The limitations of earlier autorefractors were alignment issues, accommodation problems, and irregular astigmatism.[9] The activity deals with the general comparison of objective and subjective autorefractors, types of autorefractors, general characteristics of autorefractors, commercially available autorefractors, their indications, and technique of performing autorefractometry, interfering factors, and clinical significance.

Proximal accommodation errors should not be used in young children with cycloplegic retinoscopic as proximal accommodation errors can occur, resulting in over minus refraction compared to subjective refraction.[33] Poor fixation- The patient blinks excessively and doesn't fix the primary gaze.[34] High refractive errors- The autorefractors may not be fairly accurate at high refractive errors.[4] Pupil dilatation- Small and constricted pupil may interfere with autorefractor results.[35] Media opacity – The results are unreliable, such as pterygium, adherent leucoma, corneal opacity, cataract, etc.[36] Involuntary eye movement- Nystagmus, opsoclonus, myoclonus, ocular bobbing, etc., all interfere with autorefractor readings.[37] Other factors- Pseudophakia, amblyopia, age-related macular degeneration, etc Lack of assessment of media opacity- Keratoconus, pterygium, cataract, etc Cost- They are relatively costly equipment's as compared to retinoscopy Non-portable- These instruments occupy more space compared to retinoscopy instruments Breakdown- The software or the electrical circuit can break down, sometimes interfering with the results. Early Optometers Limitations The limited acceptance of optometers in practice is due to alignment issues, irregular astigmatism, and accommodation.[38]

Autorefraction is a basic investigation to assess the refractive error in a patient presenting to the routine outpatient setting. It serves as a start point for subjective refraction and helps optometrists and ophthalmologists to pinpoint the refractive error accurately. Patient satisfaction and outcome result from the multidisciplinary approach of the ophthalmologist and the optometry team. Autorefractors also help to reduce patient waiting time at large volume centers.[39]

The nursing staff also handles the autorefractor at most centers to assist the optometrists and ophthalmic technicians. They should be taught and be aware of this common ophthalmic investigation for rapid patient assessment and reduce chair time in a busy OPD.[40]

The senior nursing staff must assist, teach and monitor the technique of autorefraction being performed by the junior nursing staff. Junior nursing should be monitored and motivated daily to improvise their ophthalmic skill for better patient management and care.[41]