[The Octopus G1 program. Description and use].
The Octopus global analysis Program G1 was developed as a glaucoma program. It is the combination in a single program of: examination procedures, visual field assessment methods. The whole examination is carried out in three phases: the first phase measures 59 test locations in the central 30 degrees field. All locations are measured with the normal strategy. The local threshold is precisely determined to +/- 1 dB by the proven bracketing method. At the end of the first phase, the system automatically calculates the key values (visual field indices) for mean defect and loss variance. the second phase, which retests the same central field, starts from the threshold values measured during phase one. The additional indices corrected loss variance and short term fluctuation, are calculated. in the last phase 14 selected peripheral points between 30 and 60 degrees excentricity with particular emphasis on the superior and inferior nasal step are determined in a qualitative test. Visual field changes can be detected and categorized in three major groups: (Flammer and coll., 1985). 1. local defects or scotomas in varying depths and sizes. 2. diffused depression of the whole field. 3. Increased short-term. The original index called Corrected Loss Variance could determine an early defect before the existence of a light scotoma. Particularly, an increased Corrected Loss Variance indicates that the deviations are due to real scotomas and not just to scattering effects. The therapeutic decision could be more rational.