A visual field index for calculation of glaucoma rate of progression.
(2008) In American Journal of Ophthalmology 145(2). p.343353 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 agecorrected 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 agecorrected 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 cutoff for pattern deviation was, at mean deviation, worse than 20 decibels (dB) in fields in which the eightyfifth 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:
http://lup.lub.lu.se/record/1035297
 author
 Bengtsson, Boel ^{LU} and Heijl, Anders ^{LU}
 organization
 publishing date
 2008
 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
 18791891
 DOI
 10.1016/j.ajo.2007.09.038
 language
 English
 LU publication?
 yes
 id
 a829d6d47b724e76a0028a1b0cf9a65d (old id 1035297)
 alternative location
 http://www.ncbi.nlm.nih.gov/pubmed/18078852?dopt=Abstract
 date added to LUP
 20080228 09:10:05
 date last changed
 20170924 04:15:19
@article{a829d6d47b724e76a0028a1b0cf9a65d, 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 agecorrected 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 cutoff for pattern deviation was, at mean deviation, worse than 20 decibels (dB) in fields in which the eightyfifth 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.}, author = {Bengtsson, Boel and Heijl, Anders}, issn = {18791891}, language = {eng}, number = {2}, pages = {343353}, 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}, }