Visual Fields - documenting progression

Glaucoma Progression Analysis (GPA)

• change in the total deviation values over time may be due to factors other than glaucoma such as advancing cataract or decreased pupillary size.
• by using the pattern deviation values, the GPA software specifically targets the localized change associated with glaucoma
• If there were a diffuse component to the glaucomatous change, it would not be reflected in the GPA result, but the more likely localized component due to the formation of new glaucomatous defects or the expansion and deepening of existing defects would be characterized
• change needs to be present in 3 consecutive visual fields before progression can be confirmed
• if progression has occurred and there is a resultant change in therapy, the clinician should
  establish a new baseline so that any additional progression can be found
• if the patient undergoes ocular surgery or develops another ocular condition, new baseline
  tests after he stabilizes should be selected for use in evaluating subsequent examinations

Mean deviation plot

• gives the slope associated with change in the mean deviation
• this change will include anything that affects the subject’s visual sensitivity, including advancing cataract, and that it may not reflect change due to glaucoma.

• The GPA software will automatically assess the next visual field (and the next) to determine if that change is repeatable.
• If it is present on two consecutive tests, a half-filled triangle will appear at the location
• For repeatable change on three consecutive tests, a closed triangle will appear.
• The GPA software then assesses the repeatability of three or more points and gives a plain-language report of “possible progression” if two consecutive fields show that
• the same three or more points changed from baseline or “likely progression” if three consecutive fields show change at the same three or more points.