AutoPeri(NM)

INTERPRETATION OF AUTOMATED PERIMETRY

Automated perimetry

© Thomas R

Automated perimetry

I.Perimetry logic

II.Identifying field defects

III. Criteria for glaucomatous defects IV. Detecting glaucomatous progression

V.Advanced field defects

© Thomas R

Bracketing strategy

B

A

© Thomas R

Normal thresholds

•Mean threshold in disease-free fields

•In a given age group

•At a given location in the visual field

•Mean normal values are stored in the automated perimeter and compared against patient data

© Thomas R

Computers and ease of interpretation

Sensitivity

+

Simple set of rules

Computer

Diagnosis

© Thomas R

Perimeter logic (1)

•Sensitivity determined at each location

•Normal range developed

•Normal range is arbitrary

–Includes the values of 95% of the normal population

© Thomas R

Perimeter logic (2)

•‘Abnormal’ values include the lowest 5% of those in normal individuals

•Therefore, 5% of normal individuals will be labelled abnormal

‘Abnormal’ is not the same as diseased

© Thomas R

Perimeter logic (3)

•General population – 100 tested

•1% glaucoma; 99% normal

•Six will have abnormal tests:

•1 glaucoma patient

•5 normal individuals

© Thomas R

Perimeter logic (4)

•Clinic population – 100 tested

•30% glaucoma; 70% normal

•33 will have abnormal tests

•30 glaucoma patients

•3 normal individuals

© Thomas R