Some History of the FDT Perimeter

My colleague Ivan Goldberg has goaded me into writing this because he thinks there is confusion about the origins of the FDT method and has suggested that I advertise the history a little more. A published commentary on an article by Ivan and colleges on SWAP and FDT also covers some of these issues[26] and see[5].

As that article mentions I originally had the idea that the FD illusion might be useful in glaucoma diagnosis back 1989. Following some experiments two patent applications were filed (in the USA and Australia) and an ARVO abstract was published on our preliminary results[1]. The USA version and another of my other patents are cited in the FDT manual, the perimeter being produced under licence to the ANU, owners of the IP. After an initial unsuccessful venture with an Australian firm we entered a period I when was discovered by Welch Allyn, who as it happened had recently taken a corporate decision to enter the glaucoma diagnostic market. I met with Rich Newman, now a WA vice president, at the 1990 ARVO meeting. Following that meeting Welsh Allyn signed a first refusal agreement with the ANU and they began to fund my research. We went through two sets of clinical trials before they decided to commit to a larger program. Since my institution was not really set up for large-scale clinical trials I contacted Ivan Goldberg, a leading glaucoma specialist in Australia and member of the Board of the Australian College of Ophthalmologists, and he agreed to let us set up a larger trial, involving a cohort of 330 people, in his practice.

This trial began in February 1991 and carried on for nearly 2 years during which time subjects were tested up to 7 times. After a hiatus during which WA statisticians looked over the data, and some corporate decision time, a short trial for USA FDA approvals occurred in early 1994. From 1993 onwards WA engineers discussed hardware design for a test instrument. The basic threshold method and the ability to easily modify the size and location of the test regions was worked out. By December 1993 a design for the electronics had been finalised this remains largely unchanged in the current model.

During this period WA had been looking for one or more sites in the USA to test the final instrument. In May 1994, following ARVO, my colleague Andrew James and I met with WA engineers to discuss issues of hardware specification and methods for quality control of the hardware. They were trying to glean what they could from our knowledge of video methods. Around this time WA succeeded in attracting Chris Johnson to run clinical trials in the USA. In a meeting at WA following the ’94 JERMOV conference in Montpellier we decided that we should move to more test regions in subsequent experiments. This was in part driven by the encouraging results we had obtained with a multi-region pattern ERG using FD stimuli, co-developed by myself and Andrew James. That test, and its associated patent [USA, Patent, No. 5,539,482; filed March 1, 1993], describe the use of 9 or more stimulus regions. I was pushing for a more sophisticated tessellation of stimuli while the engineers opted for the version you see in the FDT today that simply cut our original stimuli in to several about equal sized pieces. I visited Chris on the way home to Australia to see how things were going with the first of his trials.

During this period I was pushing for more money to be spent on investigating the sources of the FD illusion and also the multi-region FD PERG (MFP). Welch Allyn took the decision that due to limited resources and a higher than expected costs to get the FDT to market that they would only fund Chris’ work, which was critical to producing a final production model and obtaining normative data. This was initially disappointing but in the end it was necessary for the perimeter to get to market. Also, Chris undoubtedly added a great deal of experience and perimetric know-how to the project, which ultimately made the FDT as successful as it is. He added the MOBS threshold method for example.

Since I was not being funded to do glaucoma research this ultimately lengthened publishing delays which had already been made very long by confidentiality issues. Also, I felt strongly that in the end the FDT would require further scientific underpinning and so I have tended to pursue those areas. Consequently the original, ’89 study came out in 1992[2], and the 1990 experiments were only published recently[3,4,5]. The 1993 studies with Goldberg and James, including MFP, also were delayed[6,7,8], as was the work on possible spatial undersampling[9] of M_y-cells, reported originally in my 1990 ARVO abstract[1]. I am currently conducting a retrospective study on our glaucoma suspects with Ivan Goldberg that we hope will be out this year.

In the interim I have published some PERG[10,11,12] and psychophysical studies of FD[13], and in other areas such as insect vision[14,15,16] (an older interest now mainly carried on through co-supervising research students and post-docs), vertebrate visual electrophysiology[17,18], eye movements[19], texture[20,21,22] and brightness[23,24,25] effects. Given all these distractions and delays it is understandable that many assume Chris is the inventor of the FDT. Certainly Chris’s participation has been critical to validating the method and the recent developments of the commercial perimeter. On the clinical side I have been working with Andrew James for several years now on new methods for multi-focal analysis of the visual field which we find have significant advantages over the present technology for glaucoma and other neurological disorders.

References (For a more complete listing and some PDF files)

1. Maddess, T. & Henry, G.H. (1990). Density of Nonlinear visual units and glaucoma. Invest. Ophthal. Vis. Sci., 31, 230. (Sarasota, USA).

2. Maddess, T. & Henry, G.H. (1992). Nonlinear visual responses and visual deficits in ocular hypertensive and glaucoma subjects. Clinical Vision Sci., 7, 371-383.

3. Severt, W.L., Maddess, T. & Ibbotson, M.R. (2000). Employing following eye movements to discriminate normal from glaucoma subjects. Clinical Exp Ophthalmol, 28, 172-174.

4. Maddess, T. & Severt, W.L. (1999). Testing for glaucoma with the frequency doubling illusion in the whole, macular and eccentric visual fields. Aust. N. Z. J. Ophthalmol., 27, 198-200.

5. Maddess, T., Severt, W. & Stange, G. (2001). Comparison of three tests using the frequency doubling illusion to diagnose glaucoma. Clinical Exp. Ophthalmol. 29, 359-367.

6. Maddess, T., James, A.C., Goldberg, I., Wine, S. & Dobinson, J. (2000). A frequency doubling illusion based multiregion PERG for glaucoma. Invest. Ophthalmol. Vis. Sci., 41, 3818-3826.

7. Maddess, T., James, A.C., Goldberg, I., Wine, S. & Dobinson, J. (2000). Comparing a parallel PERG, automated perimetry and frequency doubling thresholds. Invest. Ophthalmol. Vis. Sci., 41, 3827-3832.

8. Maddess, T., Goldberg, I., Wine, S., Dobinson, J., Welsh, A.H. & James, A.C. (1999). Testing for glaucoma with the spatial frequency doubling illusion. Vision Res., 39, 4258-4273.

9. Maddess, T., Hemmi, J. & James, A.C. (1998). Evidence for spatial aliasing effects in the Y-like cells of the magnocellular visual pathway. Vision Res., 38, 1843-1859.

10. Maddess, T., Bedford, S., James, A.C. & Rose, K.A. (1997). A multiple frequency, multiple region pattern electroretinogram investigation of nonlinear retinal signals. Aus. N. Z. J. Ophthalmol.,25, 94-97.

11. Bedford, S., Maddess, T., Rose, K.A. & James, A.C. (1997). Correlations between observability of the spatial frequency doubled illusion and a multi-region PERG. Aus. N. Z. J. Ophthalmol.,25, 91-93.

12. James, A.C., Maddess, T., Rouhan, K., Bedford, S. & Snowball, M. (1995). Evidence for My-cell involvement in the spatial frequency doubled illusion as revealed by a multiple region PERG for glaucoma. J. Opt. Soc. Am. VSIA Tech. Dig., 1, 314-317.

13. Maddess, T. & Kulikowski, J. (1999). Apparent fineness of stationary compound gratings. Vision Res., 39, 3404-3416.

14. Yang, E.C. & Maddess, T. (1997). Orientation-sensitive neurons in the brain of the honeybee (Apis mellifera). J. Insect Physiol., 43, 329-336.

15. Davey, M., Srinivasan, M.V. & Maddess, T. (1998). The Craik-O’Brien-Cornsweet Illusion in Honeybees. Naturwiss., 85, 73-75.

16. Maddess, T., Davey, M. & Yang, E. (1999). Discrimination of complex textures by bees. J. Comp. Physiol. A, 184, 107-177.

17. Ibbotson, M.R., Mark, R.F. & Maddess, T. (1994). Spatiotemporal response properties of direction selective neurons in the nucleus of the optic tract and dorsal terminal nucleus of the wallaby. J. Neurophysiol., 72, 2927-2943.

18. Hemmi, J.M., Maddess, T. & Mark, R.F. (2000). Spectral sensitivity of photoreceptors in an Australian marsupial, the tammar wallaby (Macropus eugenii). Vision Res., 40, 591-599.

19. Ibbotson, M.R. & Maddess, T. (1994). Temporal frequency and binocularity govern adaptation of the human oculomotor system. Exp. Brain Res., 99, 148-154.

20. Nagai, Y., Maddess, T. & Ankiewicz, A. (2001). Discrete algebra on cellular automata and binary textures. Mem.  Kokushikan U. Centre Inf. Sci. 22, 51-64.

21. Maddess, T. & Nagai, Y. (2001). Discriminating isotrigon textures. Vision Res., 41, 3837 - 3860.

22. Nagai, Y. & Maddess, T. (2000). Randomness on binary textures in vision research. Am Inst Phys CP Statistical Phys.,519, 501-503.

23. Maddess, T., Davey, M., Srinivasan, M.V. & James, A.C. (1998). The Craik-O’Brien-Cornsweet effect and brightness induction both proceed by the spreading of brightness information. Aus. N. Z. J. Ophthalmol., 26, 95-97.

24. Maddess, T., Srinivasan, M.V. & Davey, M.P. (1998). Response to Pessoa and Neumann on filling-in effects. Trends Cog. Sci.,2, 425.

25. Davey, M., Maddess, T. & Srinivasan, M.V. (1998). The spatiotemporal properties of the Craik-O'Brien-Cornsweet effect are consistent with "filling-in". Vision Res., 38, 2037-2046.

26. Maddess, T. (2000). Perspectives on the use of frequency doubling and short wavelength perimetry for the diagnosis of glaucoma. Clinical Exp. Ophthalmol., 28, 245-247.