hvf progession

HVF PROGRESSION

SIVATEJA CHALLA

• Glaucoma is progressive optic neuropathy characterised by progressive loss of retinal ganglion cells

• Progress is totally irreversible

In this scenario,the main thrust in glaucoma management is diagnosing progression so as to halt it.

Can be monitored….structurally• HRT• GDX• OCT

functionally• Perimetry

• Clinical detection of changes in the optic disc and RNFL corroborated by visual field assessment still remain the accepted methods to detect progression in glaucoma

• Drawback in clinical evaluation of the optic disc and RNFL is that it is subjective with considerable intra and inter observer variation

• VF is gold standard to asses progression objectively in glaucoma

• conventional perimetry is probably not the most sensitive technique to monitor changes in the visual field.

• lot of programs like modified Andersons criteria,

overview printout, Peridata and delta program of Octopus, and Glaucoma change & Probability analysis in the Humphrey are all designed to facilitate interpretation of change

progression

Trend analysis

Event analysis

PROGRESSIONTREND ANALYISIS

• various parameters TD,MD, CPSD is calculated by the software to analyze change and compared to the threshold value

• significantly negative, then it is said to have progressed

EVENT ANALYSIS

• determined when the threshold deteriorates beyond the previously prescribed level

• uses paired t tests, confidence intervals, point wise glaucoma change probability analysis

Trend analysis

Event analysis

• HVF STATPAC prints field in four formats1.Overview print out2.Change analysis3.Glaucoma change probability plot(GCP)4.Glaucoma progression analysis (GPA)

OVERVIEW PRINT OUT• 16 serial follow ups of a particular

patient, just by a glance• does not give us the reliability

indices• all the fields being compared should

be of the same strategy.

CHANGE ANALYSIS PRINT OUT• Produces analytical summary of changes in

patients visual field from time of earliest test to most recent test

• Box plots are seen• Also gives summary of four global indices

SF,PSD,CPSD and MD

CHANGE ANALYSIS PRINT OUT

Linear regression analysis

Glaucoma change probability

• An improved sensitivity is designated as an Open triangle and a worsened sensitivity is depicted as close triangle

• >3 closed triangles depicts progression

• Important limitation is use of MD as an indicator of progression is its inability to distinguish between focal and diffuse change. Cataracts are characterised by the diffuse perimetric defects which may coincide or be confused wit glaucomatous progression.

GLAUCOMA PROGRESSION ANALYSIS• Developed by carl zeiss,event based• Change based on pattern deviation plot• Requisites2 base line VF and 1 f/u VF• Up to 14 follow up tests can be compared with

baseline

X signifies that the data at that point was out of range for analysis.

BASE LINE EXAMINATIONS

VISUAL FIELD HISTORY AND TREND

CURRENT EXAMINATION

GPA baseline examination• VFI a new summary measurement of visual field status

expressed as a percent of a normal age-adjusted visual field.

VFI rate of progression analysis

Current VF summary

GPA Alert

• Possible progression: same 3 or more points show deterioration in at least 2 consecutive tests

• Likely progression: same 3 or more points show deterioration in at least 3 consecutive tests.

problems• Learning curve• Long term fluctuations• Already Bad fields• Other pathologies

THANK YOU