Progressive shrinkage of the visual field during automated perimetry following traumatic brain injury - Patients' experience

Purpose: To establish a distinction between the visual field and the attent ional field in patients with traumatic brain injury, and to elucidate the p atients' experience with attentional field defects. Methods: We retrospecti vely reviewed the clinical observations of 25 traumatic brain-injury patien ts. On the basis of the 30-degree visual field printout, we identified six patients with concentric contraction and analyzed their visual fields by co mparing the two consecutive stages of the Octopus NI screening and threshol d program. The recorded fields were compared with the results of clinical c onfrontational field testing. Three of the six patients had been asked to d escribe their experience during automated perimetric evaluation. Results: T he visual fields showed various degrees of contraction, some severe. All si x showed progressive shrinking of the field during the perimetric evaluatio n procedure. However, no defects were apparent with confrontational field t esting. False-negative catch trials ranged from 0 to 50% (mean 18.1%). When asked, the three patients had all described a striking progressive darkeni ng of the background and shrinkage of the visual field during the automated perimetric examination. Conclusions: During automated perimetry, patients with traumatic brain injury may develop mild to severe concentric contracti on, which is progressive over time. This is associated with the experience of dramatic obscuration of the visual field. This may reflect an organic di sturbance in attentional mechanisms, revealed when executing dual task dema nds. When analyzing results from automated perimetry in such patients, a di stinction should be made between visual and attentional fields.