Use of a portable head mounted perimetry system to assess bedside visual fields

Abstract

Aim: This study was designed to test the ability of a portable computer driven, head mounted visual field testing system to perform automated perimetry on patients at their bedside and to compare these results with the "gold standard" for bedside examinations, confrontation visual fields.

Methods: The Kasha visual field system is a portable automated perimeter which utilises a virtual reality headset. 37 neurosurgery patients were examined at their bedside with a central 24 degree suprathreshold testing strategy after confrontation visual field testing. The patterns of visual field defects were categorised and compared with the results of confrontation testing.

Results: A total of 42 field examinations were completed on 37 patients, and the average testing time for both eyes was 4.8 minutes with the perimetry system. Each of the 11 fields (100%) classified with defects on confrontation testing was similarly categorised on head mounted perimetry. 26 out of 31 (84%) visual fields were normal on both confrontation and perimetry testing, while five out of the 31 fields (16%) which were full on confrontation had visual field defects identified by head mounted perimetry.

Conclusion: The head mounted, automated perimetry system proved easily portable and convenient for examining neurosurgical patients at their bedside in the perioperative period. The device demonstrated equal sensitivity to confrontation visual field testing methods in detecting field defects and offers the advantage of standardised, quantifiable testing with graphic results for follow up examinations.

Figure 1

Head mounted perimetry test in progress with perimetrist monitoring examination on the computer screen.

Figure 2

Head mounted perimetry field of a 58 year old man 4 days after a transsphenoid resection of a pituitary adenoma, with a classic bitemporal field defect consistent with chiasmal dysfunction.

Figure 3

Head mounted perimetry fields of a 37 year old man taken preoperatively (A) and 2 days following a right temporal lobe resection for an anaplastic astrocytoma (B). The left superior homonomous quadrant defect is consistent with the right temporal lobe resection.

Figure 3

Head mounted perimetry fields of a 37 year old man taken preoperatively (A) and 2 days following a right temporal lobe resection for an anaplastic astrocytoma (B). The left superior homonomous quadrant defect is consistent with the right temporal lobe resection.

Figure 4

Head mounted perimetry field of a 34 year old woman 3 days following a craniotomy for central nervous system sarcoid (A). The three quadrant defect in the left eye (B) and enlarged blind spot in the right eye correlated well with the results of a Humphrey field examination performed 3 months earlier (C).

Figure 4

Head mounted perimetry field of a 34 year old woman 3 days following a craniotomy for central nervous system sarcoid (A). The three quadrant defect in the left eye (B) and enlarged blind spot in the right eye correlated well with the results of a Humphrey field examination performed 3 months earlier (C).