Retinoscopy

18 Questions

Which instrument is commonly used to perform objective retinoscopy?

Photorefractor

What is the main advantage of photorefraction over retinoscopy?

Requires less patient attention

Which component of the eye reflects light back to the camera in photorefraction techniques?

Eye defocus

What is the purpose of a transposition in retinoscopy?

To convert negative to positive form

Which technique can be particularly useful for testing infants and young children due to requiring less cooperation?

Photorefractive methods

In retinoscopy, what do (+) cyl lenses aim to achieve when added until neutrality is obtained in the most plus meridian?

Neutralize the most plus meridian

What is the purpose of using a trial frame and trial lenses in eye examinations?

To observe eye movements better in children and bedridden patients

In Mohindra's Set Up for retinoscopy, why is it important to have the room completely dark?

To enhance the visibility of the retinoscope reflex

What type of lenses are used in screening exams with Mohindra's Set Up?

Loose lenses or skiascopy bars

Which instrument is specifically designed for objective retinoscopy?

Retinoscope

What is the main purpose of using prisms in refractors or phoropters?

To measure astigmatic axis and power

Why are minus cylinders used from -0.12DC to 6.00DC in certain eye examinations?

To correct myopia during retinoscopy

What is the purpose of placing a lens ≥+1.50D during the eye examination process?

To relax the patient's accommodation

What is the recommended working distance for performing retinoscopy?

50 cm

Which part of the eye is scoped with the examiner's OD during a 3-eye retinoscopy?

Right eye

What is the purpose of disinfecting the phoropter with alcohol?

To prevent infection transmission

What should the examiner do to ensure that they are close to the patient's visual axis during retinoscopy?

Scope OD with OD and OS with OS

Which feature should be adjusted on the phoropter to ensure correct alignment with the patient's eyes?

Vertex distance

Study Notes

Accommodation

MEM or BELL Accommodation is used for instrumentation
Refractor or phoropter, Skioscopy bars, Trial lenses, and trial frame are used
Trial lenses and frame are used for children who cannot stand behind phoropter and for bedridden patients

Trial Lenses and Frame

Used for children who cannot stand behind phoropter and for bedridden patients
Lenses are larger in diameter, allowing the examiner to observe eye movements better
Verify distance Rx and near Rx

Mohindra's Set Up

Examiner sits 50cm from the patient in a completely dark room
Uses loose lenses or skiaoscopy bars
Retinoscope light intensity is adjusted to observe the reflex while keeping the patient comfortable
Have the patient look at the light while scoping the meridians and neutralizing

Phoropters/Refractors

Phoropters and refractors are interchangeable terms
Used for sphere and cylinder lenses
Jackson cross cylinder is used for astigmatic axis and power
Risley rotating prisms are used for phorias and vergences

Objective Retinoscopy

Refractive error is determined without patient input
(+) cyl lenses are added until neutrality is obtained in the most plus meridian
Recording: OD: +2.00-1.00x060, 20/30 NIPH OS -3.00-3.00x120, 20/20

Transposition

Transposition of negative to positive form: +3.00 − 1.00𝑥090 = +2.00 + 1.00𝑥180
+3.00 − 1.00 = +2.00 −1.00 𝑐𝑜𝑛𝑣𝑒𝑟𝑡𝑠 𝑡𝑜 + 1.00 090 + 090 = 180

Photorefraction

Axial and paraxial techniques
Measures refractive error and accommodative response
Rapid and objective, requires patient attention for short periods
Useful for testing infants and young children

Phoropter Set Up

Disinfect with alcohol, remove corrective lenses, measure IPD, and adjust height of chair
Adjust IPD in phoropter, level phoropter, vertex distance (12mm), and check pantoscopic tilt
Place target of 20/200 or larger with R/G filter at distance

Test your knowledge on optometry equipment and procedures including MEM or BELL accommodation, skiascopy bars, trial lenses and frames, prisms, occluders and more. Learn about the instruments and techniques used in eye examinations.

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