Accommodating spasms eye
In a recent retrospective study of 160 m TBI patients, Ciuffreda et al.
found that approximately 4 percent were clinically diagnosed with accommodative excess , with 41 percent having some type of clinically documented accommodative dysfunction.
Additionally, the patient manifested a markedly reduced accommodative convergence-to-accommodation (AC/A) ratio (1.33:1) that returned to normal (3:1) without treatment 18 months after the injury .
Although accommodative insufficiency has been the most common accommodative abnormality studied in TBI , several authors have reported overaccommodation, also termed accommodative excess, pseudomyopia, or even frank "accommodative spasm" .
These latter two components provide only a small contribution to the overall accommodative response under normal viewing conditions .
The four components interact nonlinearly to produce the overall dynamic and static accommodative response .
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.
Many of the earlier studies employed accommodative amplitude as the primary or sole index of accommodative dysfunction.
Tonic accommodation is commonly thought to result from baseline neural input from dual innervation of the ciliary muscle, namely the parasympathetic and sympathetic systems [3-4].
The results were compared with either 10 control subjects with no visual impairment or normative literature values where available.
Regarding the dynamic parameters, responses in those with m TBI were slowed and exhibited fatigue effects.
With regard to whiplash injuries, which can be conceptualized as an "indirect," and perhaps very mild, form of TBI , several studies found that approximately 18 to 33 percent of whiplash patients exhibited reduced accommodative amplitude [14-15], while another study showed statistically significant differences (i.e., reduction) in accommodative amplitude between 19 whiplash patients and 43 control subjects using the minus-lens test method .
Lastly, a case study reported on a 20-year-old male patient with TBI who exhibited a persistent inability to accommodate in one eye 3 years after the injury .