Accuracy of the Heijl-Krakau Method During Blind-spot Stimulation with the Head Mounted Imo Perimeter in Patients with Glaucoma and Glaucoma Suspects.

Abstract

Prcis: 13.9% of fixation loss responses by the Heijl-Krakau method were observed even in stable fixation eyes. The Heijl-Krakau method would overestimate the fixation loss responses.

Purpose: This study aimed to evaluate the accuracy of the Heijl-Krakau method by measuring eye positions during blind-spot stimulation.

Methods: Two thousand one hundred fifty-three eyes of 1155 glaucoma and glaucoma-suspect patients. All patients underwent a head-mounted perimeter imo test. The imo has an eye tracking system that records eye position during tests and assists the device with stimulating corrected points corresponding to eye movement. All stimulus presentations were classified into three groups: 1. fixation loss (FL) stimulus: responded to Heijl-Krakau stimuli; 2. non-FL stimulus: did not respond to Heijl-Krakau stimuli; 3. total stimuli: all other stimuli except for Heijl-Krakau stimuli. We compared the amount of fixation displacement between the FL, non-FL, and total stimuli by the Mann-Whitney U test. Relationships between the FL and mean deviation (MD), the FL and age were analyzed.

Results: The median fixation displacements with the FL, non-FL, and total stimuli were 3.2°, 1.4° and 1.5°, respectively. The fixation displacement in the FL stimulus group was greater than that in the non-FL and total stimuli groups (P<0.001). When we defined fixation displacement in the range of less than 1° as "stable eye fixation", 13.9% of the stimulus points corresponded to "stable eye fixation" with the FL stimulus. No significant relationships were found in the FL and MD, as well as in the FL and age.

Conclusion: In glaucoma and glaucoma suspected patients, after allowance for eye movement by imo patients still responded to the Heijl-Krakau blind spot monitor on 13.9% of occasions.. Our results suggest that the Heijl-Krakau method overestimates the FL response in glaucoma and glaucoma suspected patients.