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Chapter 5: The Schematic Eye : Eye Lane Setup for Retinoscopy Practice

Richard Reffner, COT

Typically, retinoscopy workshops are staged under less than optimal conditions. Meeting rooms are poorly illuminated—too dark to see engravings on the trial lens, or too bright for beginners to evaluate
red reflexes adequately! Problems arise trying to find trial lenses in dim light. This is compounded by lenses that have been placed in the wrong sections of the trial case. Lenses may have become smudged from repeated handling. Further problems arise from drained or dead batteries or blown bulbs—with no replacements to be found!

Various authors have suggested an alternate method. One in-office method calls for using the refractor with a schematic eye secured to the headrest of the patient examination chair. The advantages of practicing retinoscopy with this method, rather than with loose trial lenses, are numerous. Refractor practice is more realistic, since you use the very instrument employed when seeing patients. Refractor lens selection is quick; you do not have to verify lens power before selection and there is less problem setting cylinder axis.

The disadvantage of in-office training when compared to a formal workshop is that you do not have the workshop instructor’s knowledge and experience to help you. The service of a skilled retinoscopy instructor is paramount, if you are a rank beginner. Your sponsoring ophthalmologist or an ophthalmic medical assistant skilled in the art of retinoscopy may act as your mentor.

A schematic eye such as the RTE (Retinoscopic Training Eye; Franel Optical, Apopka, FL) is required. The RTE (Figure 5-12) schematic eye is a good choice because it provides a base that has the rigid flat surface needed to firmly secure the schematic eye to the headrest of the patient examination chair.

The RTE can swivel vertically, and this feature enhances alignment with the refractor’s aperture. Remember to check the optics of any schematic eye you buy. Schematic eyes with 0.50 cylinder or more are unacceptable, and should be returned for exchange.

Here’s how to use the schematic eye in the exam lane:

  1. Secure schematic eye to the headrest of the patient examination chair with a length of 3/8” Velcro strap (Figure 5-13).

    fig. 5-13a
    Figure 5-13A. Velcro strap.

    fig. 5-13b
    Figure 5-13B. Schematic eye secured to headrest of exam chair.

  2. Elevate the examination chair to a height that will position the schematic eye level with that of your eye.

  3. Swing the refractor into place and align the optics of the schematic with the open cell of the right refractor aperture (Figure 5-14).

    fig. 5-14
    Figure 5-14. Swing refractor in place.

  4. Be sure that the schematic eye is aligned as close to the back of the refractor as possible (Figure 5-15). Adjust spirit to level.

    fig. 5-15
    Figure 5-15. Be sure schematic eye is close to refractor.

  5. Tie a length of string (66 cm) to the retinoscope to check your working distance.

  6. Use trial lenses to provide the phantom refractive error. Place the lenses in the cell closest to the schematic eye.

Most skilled refractometrists prefer not to use the +1.50 retinoscopy lens built into the accessory dial of the refractor. The reason for this is to eliminate an additional lens between patient and examiner, thus eliminating two refracting surfaces that threaten you with additional annoying reflexes. The fewer lenses between you and your patient, the better!

Next, check the calibration of your schematic eye:

  1. Set the schematic eye at zero refractive error.
  2. We will use the +1.50 retinoscopy lens to aid with calibration of the schematic eye to emmetropia.* With the +1.50 retinoscopy lens in the refractor and your streak retinoscope in hand, check the red reflex for neutrality when you scope it from 66 cm.
  3. Adjust the cylinder of the schematic eye slightly in and out until a neutral end point is reached.
  4. Check your reflex by moving to and fro slightly. Note WITH when you move toward the refractor (in front of the far point) and AGAINST when you move away from the refractor (behind the far point).
  5. Once you are certain of neutrality, try to have this verified by your mentor. Then, remove the +1.50 retinoscopy lens. Tape or mark the cylinder of the schematic eye to hold the position.
  6. At this point, you will observe WITH movement consistent with that of the emmetropic eye. In other words, this is how an emmetropic eye looks without the working lens in place. Various spherical and or cylindrical trial lenses, alone or in combination, can be placed in the trial lens cells of the schematic eye to create various refractive errors. Your patient’s “eye” can now be neutralized, using the refractor lenses.

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