Shattky Optometrists

Visique Shattky Optometrists has been serving the people of Hawke's Bay with trusted expert eyecare and eyewear since 1906. We continue a proud history of family ownership with successive father & son teams Ernest & Derek Shattky, Neil & Phil Donaldson plus Mark & Tim Eagle. Using the very latest technologies and systems we specialise in Glaucoma tests, Retinal photography, Diabetic management, Therapeutic drugs, dietary supplements and Behavioural Optometry. We are ACC primary eyecare providers and CAA certificated examiners. Our speciality Orthokeratology and Keratoconus contact lens services are very successful. Using Zeiss, Nikon & Essilor quality lenses, High Fashion frames and sunglasses we excel in providing award winning choice. We provide Irlen and Cellfield specialist services for 3D, binocular problems, Amblyopia and reading problems.

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Home > How We Help > The Best Eyecare Technology > Frequency Doubling Threshold

Zeiss Frequency Doubling Threshold (FDT)

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Frequency Doubling Threshold (FDT) assessment of the Retinal Ganglion Nerve cells is a breakthrough in visual field testing that is efficient and fast.

The FDT is a very user-friendly automated visual field instrument.
It captures screening results in only 45 seconds and full threshold results in under 4 minutes per eye.

The FDT can detect glaucoma at an earlier stage than Standard perimetry. It is a very good test for answering the question 'is the disease present?'.

How does it do it? The FDT isolates a subset of retinal ganglion cell mechanisms in the magnocellular (M-cell) pathway. These M-cells have large diameter fibers and comprise only 3% to 5% of all retinal ganglion cells. The damage of these cells in the disease process makes FDT efficient and effective for the detection of visual field loss.

Clinically Validated:  World-class validation research with 3 years of comprehensive clinical trials. Large age-related normative database.

Rapid Testing Times:  Supra-threshold screening in only 45 seconds. Full threshold testing in under 4 minutes.

No Trial Lens Needed: Patients wear their own correction.  Automatically occludes the opposite (untested) eye. => No Ambient Light Affects so the test can be done in normal room lighting.


Stimulus: Frequency Doubled sinusoidal gratings (0.25 cpd; 25 Hz).

Fixation Monitoring: Heijl-Krakau fixation monitor.

Area of Field Tested: Central 30 degrees.

Test Strategies and Patterns: Supra-threshold C-20 screening, Full threshold C-20 testing, Full threshold N-30 testing.

Analysis Software: Statistical Global Indices (MD and PSD). Probability levels and deviation plot based on age-related normative references.

Printer: High-speed, high-resolution internal thermal printer.