A Viual Field Index for Calculation of Glaucoma Rate of Progreion Original Reearch Article

Purpoe To preent a new perimetric index for calculating the rate of glaucomatou progreion and to compare it performance with the traditional mean deviation index (MDI). Deign Experimental tudy decribing a device and retropective cohort tudy. Method We developed a new viual field index, the glaucoma progreion index (GPI), intended to be le affected by cataract than the MDI by calculating age-corrected defect depth at tet point identified a ignificantly depreed in pattern deviation probability map. The valid operating range for pattern deviation analyi wa etimated. When exceeding thi range, the total deviation probability map were ued for identification of ignificantly depreed point. The GPI i expreed in percentage, where 100% repreent a normal viual field and 0% repreent a perimetrically blind field, and i plotted v patient age. Rate of progreion, preented a yearly change in the GPI, i calculated by linear regreion analyi. We conducted a pilot evaluation in three group of patient: 1) eye with developing cataract, 2) eye without cataract, and 3) eye in which cataract urgery wa performed in the middle of the erie. Reult The cut-off for pattern deviation wa, at mean deviation, wore than −20 decibel (dB) in field in which the eighty-fifth percentile of the total deviation value wa ignificantly depreed. In the firt group (n = 45), the meaured rate of progreion wa greater with the MDI than with the GPI (P < .0001). The mean lo per year wa 3.6%/year for the MDI and 2.1%/year for the GPI. In the econd group (n = 42), the rate of progreion did not differ between the MDI and the GPI (P = .52); the mean were 2.7%/year and 2.6%/year, repectively. In the third group (n = 44), the confidence limit for the rate of progreion were ignificantly maller with the GPI than with the MDI (P = .04). Concluion Glaucoma progreion rate calculated uing the GPI eem to be coniderably le affected by cataract and cataract urgery than rate baed on the traditional MDI.