Sa. Vernon et Ha. Quigley, IMPROVING THE SENSITIVITY OF THE OKP VISUAL-FIELD SCREENING-TEST WITHTHE USE OF NEUTRAL DENSITY FILTERS, Eye, 8, 1994, pp. 406-409
Oculokinetic perimetry (OKP) has been developed to screen for glaucoma
tous field loss but has relatively poor sensitivity when compared with
threshold perimetry. Forty-two eyes from 42 patients with glaucomatou
s field loss on Humphrey threshold perimetry and 32 normals performed
hand-held OKP under controlled conditions of refraction and lighting.
Those who passed the standard test had their OKP cutoff determined wit
h increasing neutral density filters (NDFs) at a new point 15 degrees
from fixation in the inferotemporal held (where first glaucomatous def
ects are rarest). OKP was then repeated with a NDF that increased the
ambient light by 0.3 log units from cut off. Of the 16 glaucomatous ey
es to pass standard OKP, 9 failed the NDF test, improving the sensitiv
ity from 62% to 83% (p<0.05). These 9 eyes had field defects that were
significantly less severe (mean defect 4.85 vs 7.91 (p<0.05) and corr
ected pattern standard deviation 4.12 vs 7.00 (p<0.05) and were from y
ounger patients (mean age 56 vs 66 years; p<0.05) than those who faile
d standard OKP. None of the 32 normals failed standard OKP and only 1
of 32 failed the NDF test. The use of NDFs to customise OKP, producing
essentially a staged suprathreshold contrast sensitivity test, appear
s to increase the sensitivity of the OKP screener without degrading it
s specificity, particularly in younger subjects.