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Retinoscopy procedure

A Beginner’s Guide to Conducting a Retinoscopy Procedure

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The retinoscopy procedure and refraction is not an intuitive or easy skill to learn. It requires the optometrist to exact patience and undergo a significant amount of practice. Most importantly, optometry students and beginners should steer clear of uncooperative patients, such as babies and patients with corneal or lens pathology. However, the following information provides a few simple, but highly effective tips to help beginners complete the retinoscopy procedure.

What Is the Retinoscopy Procedure?

The retinoscopy procedure is a technique used to obtain an objective measurement of the refractive error of a patient’s eyes. This refractive error can include astigmatism, farsightedness, nearsightedness, and the need for glasses. The retinoscopy procedure is conducted with the retinoscope and should be quick, reliably accurate, and requires little cooperation from the patient.

Understanding Prescription for Retinoscopy Procedure Success

The first step in a successful retinoscopy procedure is to understand the components of a glasses prescription. The first number represents the spherical power in diopters. This number can represent the degrees of:

  • Hyperopia – plus power caused by the extra convergence required to neutralize farsightedness
  • Myopia – minus power because a divergent lens is necessary to neutralize nearsightedness

If astigmatism exists, the second and third figures will represent it. The second number refers to the power in diopters of the cylinder. It’s important to understand the cylindrical power can be represented in minus or plus cylinder form; lens transposition can convert one to the other. The third number specifies the axis in which the cylinder is neutralized. If your patient needs bifocals, “ADD” will be the extra spherical power.

Determining Retinoscopy Working Distance

When conducting the retinoscopy procedure, get started by asking your patient to fixate on a distant target. On the other hand, you get the patient to relax by dilating their eyes with a cycloplegic agent. You can start determining the appropriate retinoscopy working distance by sitting at arm’s length from the phoropter. Make sure to consider this when figuring your patient’s final spherical error.

In order to calculate the number of diopters that must be offset, take the inverse of your working distance in meters. For instance, if your retinoscopy working distance is 50 cm, subtract 2 diopters or 1/0.5m from the final spherical correction to account for this.

The Retinoscopy Procedure

Beginning on the right side, shine the retinoscopy streak into their eye and move the streak from side to side. You must decide whether the patient’s light reflex moves “with” their pupil or “against” motion. Make sure to look at the reflex in different meridians as you rotate the axis of the streak.

If the reflex has a consistent brightness and width all around, the patient doesn’t have astigmatism. In contrast, if the reflex looks dimmer/brighter or thinner/thicker when alternating the axis of the streak, then the patient does have astigmatism, and you will need to correct it.

Adjusting the Script & Achieving Neutrality

If the patient’s refractive error is spherical only, decide if you need to add minus or plus power. Use the pneumonic “SPAM” to remember:

  • Same (“with” motion) requires
  • Plus power
  • Against motion requires
  • Minus power

Then, use the spherical power dial on your phoropter to add the right amount of power until a bright red reflex light is seen without any motion that fills the pupil. At this point, you have achieved neutrality.

Retinoscopy Procedure for Astigmatism

If your patient has astigmatism, you will notice the reflex moving obliquely as you move the streak from side to side. Continue to rotate the beam until it is parallel with the reflex motion. After neutralizing the “against” or “with” movement, the secondary meridian should be 90 degrees away at the axis of the patient’s astigmatism.

Neutralize the “against” or “with” movement in the second meridian to find the cylindrical power. Repeat the retinoscopy procedure with the patient’s other eye. Make sure you subtract the retinoscopic working distance prior to writing the prescription.

Contact Keeler Ophthalmic Instruments

If you’re looking for the latest, most cutting-edge ophthalmic instrumentation, Keeler Ophthalmic Instruments can help. For more than 100 years, Keeler has been a leader in the industry.We pride ourselves in providing exceptional thought leadership, innovative instrumentation, optometry student residencies, and much more.

Contact Keeler Ophthalmic Instruments today.

About the Author Eugene VanArsdale

Eugene is the Director of Marketing Communications at Keeler Instruments. He has been with Keeler since 1982 and is co-holder of two patents for the company. Eugene has a true passion for the eye care industry and has dedicated himself to understanding the ins and outs of the optometric and ophthalmic equipment market.