Accommodative inertia, also known as accommodative infacility
, is a condition where the accommodative system has difficulty switching focus between distances.
Rouse, "Relation of symptoms to accommodative infacility
of school-aged children," Optometry and Vision Science, vol.
The least studied accommodative deficit in TBI has been dynamic accommodative infacility
. This is diagnosed when a patient exhibits a slowed accommodative response (i.e., reduced peak velocity) to a change in dioptric lens power or target distance, which can occur alone or in conjunction with either AI or AE .
This may be assessed using +2.00/-2.00 flipper lenses (Figure 7), whereby the patient views a near target through positive lenses, maintaining clarity of the target, and then the lenses are flipped to the negative ones requiring the patient to maintain clarity of the target through these; the number of repetitions/flips which can be performed in one minute is assessed (fewer repetitions are possible with accommodative infacility
as more effort is needed for clear focus) and is reported as cycles per minute (cpm) completed.
The most common dysfunctions of accommodation include accommodative insufficiency (underaccommodation), accommodative excess/ spasm (overaccommodation), and accommodative infacility
(inflexibility of accommodation) .
Patients with ABI might present with accommodative insufficiency, accommodative fatigue, accommodative lag and accommodative infacility
. Optometric intervention includes provision of appropriate lenses as well as accommodation training where appropriate.
The previous literature has revealed three types of accommodative dysfunctions in traumatic brain injury (TBI): accommodative insufficiency, pseudomyopia/ spasm of accommodation, and dynamic accommodative infacility.
The least-studied accommodative effect in TBI has been dynamic accommodative infacility, which is diagnosed when a patient exhibits a slowed accommodative response to a change in either dioptric lens power or target distance that can occur either alone or in conjunction with either accommodative insufficiency or excess .
Both patients with accommodative infacility improved significantly, and four of the five with reduced accommodative amplitude resolved as well.
Even in cases without a refractive aetiology, refractive modification is often successful Prismatic Prismatic correction is occasionally used correction in exophoria, typically in reading glasses for older patients Surgery Surgery is a last resort for any case of heterophoria, and is only rarely required Table 3 Clinical characteristics of the four main types of accommodative anomalies Symptoms/test results Accommodative Accommodative infacility
insufficiency Symptoms Near blur Difficulty changing focus (e.g.