What Word Has 2 A’s, 2 C’s, 2 M’s, 3Os, and a Single D,T,I,N?

Accommodation.  A special word when it comes to the information our visual system takes in at near.  Particularly within arm’s length.  We say it’s due to a change in the shape of the lens inside the eye, though that’s really an oversimplification.  The size of the iris plays a big role too, with its size controlling the amount of light getting through the pupil space in the first place, which controls your depth of focus.  For years we measured it with a retinoscope, though I find myself increasingly drawn to our Grand Seiko Open View Autorefractor (OVA) to objectively document what the patient is doing.  The OVA give you a real-time pattern that is easy to demonstrate to parents and other professionals.

First I’ll show you a few pictures of the OVA so you get a feel for what I’m referring to.

Here’s the instrument from a side view.  Note the open view of the rectangular opening, in this instance having a nearpoint card suspended on a rod at a 33 centimeter viewing distance from the patient’s eyes.  The viewing screen tells the examiner when the patient’s eyes are centered.

The patient above has his head on a chin rest, with his forehead positioned against he upper bar.  He looks at letters on the nearpoint card and is instructed to keep them clear.  For younger children you may use pictures.  You can ask the patient questions about the near target if attention is a factor.  The examiner can watch the patient’s pupil centered in the viewing screen, and it should constrict as the patient is accommodating.

We typically record distance measures of focus, while the patient is looking through a window across the room.  You need enough unobstructed space to make sure the patient isn’t accommodating, but you’ll also be able to judge that by looking at the numbers on the screen as focusing state  is being recorded.

So here’s a printout of a representative recording.  Right eye <R> is the upper and left eye <L> is the lower.  The computer samples five times and then gives its best fit result.  We are more interested in the consistency or variability of the five readings than in the best fit data.   The printout to the far left has the distance findings.  For the R eye, the last four of the five findings are +0.25-0.50cx140-ish, so it’s a good bet that is the “true” distance finding as the best fit singular number under the line shows, and that the accommodative posture was at its resting state.  For the L eye, the same holds true except the value is Pl-0.25.

The printout to its right is for near, and it shows accommodative flux for both eyes.  No two findings in succession match each other.  That flux is more important to us than the best fit singular finding.  If you repeat the finding through a tentative nearpoint plus lens addition, and/or yoked prism trial, you can look for increased stability of the accommodative profile.  Ultimately the results of vision therapy are aided by progress evaluations showing change in the data from baseline values.

When talking to parents about this, you can demonstrate the data rather than trying to describe what your retinoscope shows which is very valuable and insightful, but relatively abstract to a patient.  For the accommodative system, it’s the cardiac analog of stethoscope sounds vs. an EKG printout.  One isn’t necessarily a substitute for the other.

A few other applications.   When there is pseudomyopia, or accommodative spasm tendencies, the distance findings will show fluctuations in value similar to the near values above, where they will differ from one another by a diopter or more.  When the patient has amblyopia, the values between the right and left eyes often differ, because accommodation is usually substandard through the amblyopic eye.   Similarly for ABI, or any other condition affecting accommoodation, sequential objective measures that are demonstrable in printout form are very valuable.

Preparing this piece took me back nine years ago to the lovely editorial that Dr. Irwin Suchoff, then editor of the Journal of Behavioral Optometry, wrote about the book from which these concepts are derived, and what a joy it was to work with my co-author, Dr. Werner.  The cover graphic was designed to celebrate the intelligent use of auto-refraction as smart retinoscopy.

– Leonard J. Press, O.D., FCOVD, FAAO

6 thoughts on “What Word Has 2 A’s, 2 C’s, 2 M’s, 3Os, and a Single D,T,I,N?

  1. “A special word when it comes to the information our visual system takes in at near. Particularly within arm’s length. We say it’s due to a change in the shape of the lens inside the eye, though that’s really an oversimplification. The size of the iris plays a big role too, with its size controlling the amount of light getting through the pupil space in the first place, which controls your depth of focus.”

    Don’t disagree with this, but the MOST important part of accommodation is the relative strain on the ciliary body for the task requested of the viewer. As you say ‘particularly within arm’s length’ which is where school children spend most of their time. Very few of us are especially well-suited to managed extended periods of near work, perhaps less than 15%. Of the rest, there is a significant number (20-25% of school children) who will be encumbered by the strain of ciliary muscle tension, some to greater degrees than others. Many ODs are reluctant to correct for hyperopia until it reaches near pathological levels (~+3.0 D, cyclo), but this does not take into account the behavioural aspects of accommodation, or the fact that these children are at a real physical disadvantage with near word compared to their low-myope classmates.

    If you can’t afford the $18k for the GSO, consider a simple and inexpensive alternative: Cycloplegic refraction. Very effective in determining latent stress on the ciliary body. Research shows that after about 3 years of age, the refractive ‘stance’ of the eye is pretty well established, and that correcting even for low hyperopia will not induce an increase in refractive error. What it will do, on the other hand, is even the playing field for all children. While there should be some element of muscular tension for reading, we need to ensure we are taking into account any excess strain and how this impacts over the course of many hour, many days, many weeks.

  2. My ICO professor used to say, “a little plus goes a long way”, and I have found over the years how right he was based on patient symptoms, MEM, and other OEP tests. We now have research proving that Optometry might prescribe more eyeglasses than Opthalmology based on our greater knowledge of neuro-optometry, while their knowledge treated the patient’s eye as a camera.

    For me, I love the objective retinoscope as it tracks the accommodation system through pseudomyopia, spasm, lag of accomodation and of course refraction.
    I agree with Dr. Boulet regarding Cycloplegic refraction for esotropia, and I would add that most of my basic refraction is done with great results with 2.5% neosynephrine gtts (relaxing the iris without accommodation
    changes). Pretesting (pupils, etc is done first) then the moisture drops, then the refraction, then the medical portion of the examination, closing out with Kowa Stereo camera pictures.

    Finally, if you want wavefront refraction, corneal maps, pupil size maps, contact lens maps, pupil size refraction for day and night refraction, all in color, I like the OPD 111, although I agree with Dr. Press that with his practice, the GSO is nice to track changes.

  3. Just to clarify: I don’t only cyclo for ET, but in most cases of hyperopia, astigmatism, and even low myopia. Too many children overaccommodate to meet the requirements of extended near work, and this is too easy to miss without cycloplegia of the ciliary body, not just the iris. Neo-synephrine (you do mean phenylephrine, as opposed to the nasal spray…?) will not provide the insight into ciliary body tonus that is required to properly assess needs for the classroom. I agree that PE can assist in retinoscopy, and likewise it can be useful for A/R, but this is not the same.

  4. I have been using this device for several years in my clinical research, especially over the past few years in my TBI oculomotor studies. It is a great system to get objective documentation of an accommodative dysfunction, for example before and after some form of intervention. It also gives you insight into what is happening dynamically (e.g., 200 msec overshoots) that really cannot be determined any other way. That is, the abnormality can be both visualized on the computer trace and also quantified in its dynamic mode. Of course, other more traditional clinical optometric techniques should also be used as part of one’s overall armamentarium.

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