Which instrument uses a projected light target controlled by a handle on a pantograph?

Which instrument uses a projected light target controlled by a handle on a pantograph?

• A. Goldmann Bowl Perimeter
• B. Humphrey Field Analyzer
• C. Autoplot Tangent Screen
• D. Octopus Perimeter

Answer: (C)

This question highlights the manual control of stimulus placement on a tangent screen. In this setup, a flat tangent screen is positioned at a fixed distance from the patient, and the light stimulus is projected onto the screen. The key feature is a hand-held control connected to a pantograph—the mechanism that translates the examiner’s movements into precise positioning of the light target on the screen. This combination of a projected light target and a pantograph-controlled handle is what defines the Autoplot Tangent Screen. The other instruments use different geometries or automation: for example, a bowl perimeter relies on a curved space rather than a tangent plane, and automated perimeters move stimuli without a pantograph.

This question highlights the manual control of stimulus placement on a tangent screen. In this setup, a flat tangent screen is positioned at a fixed distance from the patient, and the light stimulus is projected onto the screen. The key feature is a hand-held control connected to a pantograph—the mechanism that translates the examiner’s movements into precise positioning of the light target on the screen. This combination of a projected light target and a pantograph-controlled handle is what defines the Autoplot Tangent Screen. The other instruments use different geometries or automation: for example, a bowl perimeter relies on a curved space rather than a tangent plane, and automated perimeters move stimuli without a pantograph.