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A visual field index for calculation of glaucoma rate of progression.

Bengtsson, Boel LU and Heijl, Anders LU (2008) In American Journal of Ophthalmology 145(2). p.343-353
Abstract
PURPOSE: To present a new perimetric index for calculating the rate of glaucomatous progression and to compare its performance with the traditional mean deviation index (MDI). DESIGN: Experimental study describing a device and retrospective cohort study. METHODS: We developed a new visual field index, the glaucoma progression index (GPI), intended to be less affected by cataract than the MDI by calculating age-corrected defect depth at test points identified as significantly depressed in pattern deviation probability maps. The valid operating range for pattern deviation analysis was estimated. When exceeding this range, the total deviation probability maps were used for identification of significantly depressed points. The GPI is expressed... (More)
PURPOSE: To present a new perimetric index for calculating the rate of glaucomatous progression and to compare its performance with the traditional mean deviation index (MDI). DESIGN: Experimental study describing a device and retrospective cohort study. METHODS: We developed a new visual field index, the glaucoma progression index (GPI), intended to be less affected by cataract than the MDI by calculating age-corrected defect depth at test points identified as significantly depressed in pattern deviation probability maps. The valid operating range for pattern deviation analysis was estimated. When exceeding this range, the total deviation probability maps were used for identification of significantly depressed points. The GPI is expressed in percentage, where 100% represents a normal visual field and 0% represents a perimetrically blind field, and is plotted vs patient age. Rate of progression, presented as yearly change in the GPI, is calculated by linear regression analysis. We conducted a pilot evaluation in three groups of patients: 1) eyes with developing cataract, 2) eyes without cataract, and 3) eyes in which cataract surgery was performed in the middle of the series. RESULTS: The cut-off for pattern deviation was, at mean deviation, worse than -20 decibels (dB) in fields in which the eighty-fifth percentile of the total deviation value was significantly depressed. In the first group (n = 45), the measured rate of progression was greater with the MDI than with the GPI (P < .0001). The mean loss per year was 3.6%/year for the MDI and 2.1%/year for the GPI. In the second group (n = 42), the rate of progression did not differ between the MDI and the GPI (P = .52); the means were 2.7%/year and 2.6%/year, respectively. In the third group (n = 44), the confidence limits for the rate of progression were significantly smaller with the GPI than with the MDI (P = .04). CONCLUSIONS: Glaucoma progression rates calculated using the GPI seem to be considerably less affected by cataract and cataract surgery than rates based on the traditional MDI. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
American Journal of Ophthalmology
volume
145
issue
2
pages
343 - 353
publisher
Elsevier
external identifiers
  • pmid:18078852
  • wos:000253205000024
  • scopus:38349107673
ISSN
1879-1891
DOI
10.1016/j.ajo.2007.09.038
language
English
LU publication?
yes
id
a829d6d4-7b72-4e76-a002-8a1b0cf9a65d (old id 1035297)
alternative location
http://www.ncbi.nlm.nih.gov/pubmed/18078852?dopt=Abstract
date added to LUP
2008-02-28 09:10:05
date last changed
2017-09-24 04:15:19
@article{a829d6d4-7b72-4e76-a002-8a1b0cf9a65d,
  abstract     = {PURPOSE: To present a new perimetric index for calculating the rate of glaucomatous progression and to compare its performance with the traditional mean deviation index (MDI). DESIGN: Experimental study describing a device and retrospective cohort study. METHODS: We developed a new visual field index, the glaucoma progression index (GPI), intended to be less affected by cataract than the MDI by calculating age-corrected defect depth at test points identified as significantly depressed in pattern deviation probability maps. The valid operating range for pattern deviation analysis was estimated. When exceeding this range, the total deviation probability maps were used for identification of significantly depressed points. The GPI is expressed in percentage, where 100% represents a normal visual field and 0% represents a perimetrically blind field, and is plotted vs patient age. Rate of progression, presented as yearly change in the GPI, is calculated by linear regression analysis. We conducted a pilot evaluation in three groups of patients: 1) eyes with developing cataract, 2) eyes without cataract, and 3) eyes in which cataract surgery was performed in the middle of the series. RESULTS: The cut-off for pattern deviation was, at mean deviation, worse than -20 decibels (dB) in fields in which the eighty-fifth percentile of the total deviation value was significantly depressed. In the first group (n = 45), the measured rate of progression was greater with the MDI than with the GPI (P &lt; .0001). The mean loss per year was 3.6%/year for the MDI and 2.1%/year for the GPI. In the second group (n = 42), the rate of progression did not differ between the MDI and the GPI (P = .52); the means were 2.7%/year and 2.6%/year, respectively. In the third group (n = 44), the confidence limits for the rate of progression were significantly smaller with the GPI than with the MDI (P = .04). CONCLUSIONS: Glaucoma progression rates calculated using the GPI seem to be considerably less affected by cataract and cataract surgery than rates based on the traditional MDI.},
  author       = {Bengtsson, Boel and Heijl, Anders},
  issn         = {1879-1891},
  language     = {eng},
  number       = {2},
  pages        = {343--353},
  publisher    = {Elsevier},
  series       = {American Journal of Ophthalmology},
  title        = {A visual field index for calculation of glaucoma rate of progression.},
  url          = {http://dx.doi.org/10.1016/j.ajo.2007.09.038},
  volume       = {145},
  year         = {2008},
}