|Fixation Losses||Fixation is plotted, if the patient moves and the machine re-tests and patient sees spot then a fixation loss is recorded.||Fixation losses above 20% may significantly compromise the reliability of the test.||
OD- Right eye;
OS – Left eye.
Note the longer the test time the more tired the patient will be.
|False POS (Positive) Errors||Patient responds to the normal whirr noise of the computer when it sounds as if is about to present a light but does not.||High false positive score occur in a “trigger happy” patient. < 33% is an unacceptable test.|
|False NEG (Negative) Errors||A brighter light is presented in an area in which the threshold has already been determined and the patient does not respond to it.||High false negative score occurs in fatigued or inattentive patients. < 33% is an unacceptable test.|
|Glaucoma Hemifield Test (GHT)||This assesses clusters of points above and below the horizontal meridian for any significant difference.||It describes the field as “Within normal limits”, “Borderline” or “Outside normal limits”||
24–2 denotes the test strategy (24 degrees temporally and 30 degrees nasally and tests 54 points).
|Mean deviation (MD)||A measure of overall field loss|
|Pattern standard deviation (PSD)||Measure of focal loss or variability within the field taking into account any generalised depression.||An increased PSD is more indicative of glaucomatous field loss than MD.|
|Probability values||These indicate the significance of the defect < 5%, < 2%, < 1% and 0.5%.||The lower the p value the greater its clinical significance and the lesser the likelihood of the defect occurring by chance.|