Abstract
Purpose: :
Visual Field Index VFI is a new perimetric index allowing evaluation of visual function level and progression in OAG. Expressed in percentage, VFI is evaluated from the age corrected defect depth of each test-point of successive pattern deviation probability maps.
Methods: :
Retrospective study on 94 eyes: 35 IOHT, 34 early OAG (0>MD>-6), 13 moderate OAG (-6>MD>-12) and 12 advanced OAG (MD<-12), with a mean follow-up of 6,5 years (4 to 8 years). Each subject perfomed a mean number of 10 SAP visual field tests (Humphrey SITA Standard 24.2), excluding tests without reliable indices. Analysis concerns: VFI progression rate and curve aspect, predictibility of further evolution at follow-up meantime, and correlation with alert signals (likely or probable evolution) of the GPA2 Glaucoma Progression Analysis .
Results: :
IOHT: VFI stability during the follow-up with a predictibility at 3 years noted in 97% of eyes; concordance with GPA2 results in 97% of cases. Early OAG: stable VFI: 88%; predictibility: 76%; no progression detected by GPA2 in 76% of eyes; VFI-GPA2 concordance in 85% of cases. Moderate OAG: stable VFI in 31% of eyes; predictibility:70%; no progression detected by GPA2: 54%; VFI-GPA2 concordance: 85%. Advanced OAG: stable VFI only in 33% of eyes; predictibility: 75%. GPA2 could not be performed in very advanced OAG with large and deep defects (30% of subjects), where VFI can be evaluated. When allowed, VFI and GPA2 concordance were present in 87% of eyes. These results point out a good VFI predictibility at 3-years follow-up, with a comparable value in all OAG subjects in this study. The authors discuss about the usefullness of VFI in OAG and about the concordance between VFI and GPA2.
Conclusions: :
VFI appears to be a complementary and reliable index for OAG follow-up survey, usefull in each evolution stage, particularly in advanced OAG and in case of recent progression, when GPA2 statistic analysis is not allowed. Predictibility at 3-years follow-up seems to be good but must be confirmed by studies with more subjects.
Keywords: perimetry • visual fields • intraocular pressure