VT Works

Accommodation is defined as the act of focusing the eyes to provide an image clear enough for interpretation. Accommodation also refers to the change in the power of the crystalline lens to bring an object into focus when stimulated by the presence of blur or proximity of the object.

Vision Therapy should strive to help patients improve their accommodative efficiency which includes facility (the ease with which a patient can shift from a relaxed posture to a stimulated posture), amplitude (the accommodative range when viewing a near target), flexibility (the ease with which accommodation is achieved), stamina (the ability to maintain accommodative accuracy without breakdown or diminishing the performance) and speed (the ability to quickly and accurately make the appropriate changes in focusing demand).

The three main areas to consider when working Accommodation are as follows:

• Facility – which is the ability to rapidly jump from different objects of regard at varying distances

• Posture – which is the position of accommodation relative to the object of regard

• Amplitude – which is the maximum amount of accommodative output possible

In my experience, there is definite value and benefit to having patients explore both “real space” activities and “simulated space” activities in instrument. It is also important to use spatial localization and spatial awareness in combination with the blur stimulus to understand where the plane of regard is in space, and where they are looking in relation to that plane. For example, if a minus lens is used to stimulate accommodation, it is useful for the patient to gain the feeling tone of looking closer to help with the ease of making the target clear. Since accommodation is intricately linked to the vergence system, via the accommodative-vergence-pupil triad, it is an important goal in vision therapy to call attention to both, even if the activity is monocular. The vergence system is used first to determine first “where is it”, which in turn, offers a greater opportunity for understanding the “what is it” of the accommodative system. When working well together, they provide input on feeling tone and increase the speed of response for both depth perception and SILO awareness.

In the therapy room, patient responses to changes in accommodative demand will include a change in pupil size as the accommodative system relaxes or constricts, changes in spatial awareness (SILO), as well as some verbalized or demonstrated discomfort through body language. If the patient is wearing a translucent patch while working on monocular accommodative activities, the Vision Therapist may also note a fusional response from the occluded eye. Under binocular conditions, a fusional (convergence or divergence) response depending on the power of the lens is included, and should be noted.

The beginning of the hierarchy for “real space” near/far shift activities we use in our office include a Bullseye near target and a Far Hart Chart, then changing to a Near and Far Hart Charts, on a monocular level. These activities begin with the patient physically touching the near target (an important step in the patient having a spatial awareness of exactly where the object is in space), and then backing away until they reach the maximum distance from which the patient can still see the letters on the distance chart clearly without guessing. Monocularly, these activities isolate accommodation and eliminate the possibility of diplopia which may be caused by an accommodative-vergence integration weakness. Lenses are introduced to include SILO awareness. Once equality and accuracy is achieved one eye at a time, the activities are repeated binocularly to incorporate a vergence demand.

The demand of an activity can also be changed by increasing or decreasing the distance from the target, the power of the lens or lenses (depending on the activity), the cognitive demand, auditory or anti-gravity load, as well as providing a dynamic target versus a static target.

Other examples of activities used in our office listed from higher level to lower level to assist patients in strengthening their accommodative systems are Wachs Mental Minus, MFBF, and Bifocal Rock, respectively. Wachs Mental Minus works on facility, posture and amplitude and even incorporates a bi-ocular demand with dissociated prisms. MFBF activities done with red/green filters not only provide information about suppression, but also whether the patient can successfully satisfy both the accommodative and vergence demands presented by the situation, effectively calibrate both systems, so they can operate together with freedom and flexibility between them. Bifocal rock asks the patient to learn to appreciate the SILO aspects of a minus lens, which compresses space, brings the target closer, and makes the image smaller. This appreciation of SILO in a bifocal rock activity is important because it demonstrates the patient’s ability to “disconnect” from the logic they possess about the real world (when an object gets smaller, logic tells us it is getting farther away) and allows the opportunity to fully understand and embrace what their visual system is experiencing.

Patients and therapists often ask which is better – Real Space or Simulated Space?  While certainly there’s arguments to be made for both, the key for me is always finding the activities which facilitate the greatest change in the patient’s experience, as well as the activities which offer the patient the strongest opportunity to transfer their new found skills into their world. If you can accomplish these two goals, no doubt your patients will be walking out visually stronger than they were when they walked in! You’re on the right track!

Cheers!