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MM Bullin, R Tesnau, J Gaa; 30 Hz Flicker mf-ERG in Normal-tension (NTG) and Low-tension Glaucoma (LTG) Detecting Preperimetric Glaucomatous Lesions . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2146.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Recently (ARVO 2001) we demonstrated our studies on non-linearities performing a 30 Hz Flicker mf-ERG in order to confirm glaucomatous lesions. Our former study based on the relationship between the DFT 1st harmonic and the DFT basewave, e.g. the quotient DFT (=Discrete Fourier Transformation): confirming a scotoma in the perimetry, in glaucoma patients the DFT quotient 1H/BW was reduced from at least 20% to 50% compared to non-scotoma areas of the same eye. In our present study we want to detect whether there will be a pathological mf-ERG result in preperimetric glaucoma suspects using this stimulation and analysing technique. Methods: 92 eyes from 46 patients with OAG (NTG and LTG) were examined - all of them presenting with at least normal visual fields in one eye and HRT results that had been classified as normal - versus a group of healthy volunteers: 90 eyes from 45 normal-sighted subjects. Each of them underwent visual acuity, perimetry by a Humphrey Field Analyzer(program 30-2), measurement of IOP by applanation tonometry, total ophthalmological eye exam including fundus examination, laser-scanning tomography (HRT, Heidelberg Retina Tomograph) and 30 Hz Flicker mf-ERG. The recording was done monocular in mydriasis with a Retiscan device (Roland Consult, Wiesbaden, Brandenburg). For stimulation we used a CRT display, 61 hexagons, full field stimulation 60°. Results: 1. In 22 eyes of 11 patients with no visual field defect we’re able to detect in 2 eyes a decreased DFT quotient (compared to the fellow-eye), 2. in 18 eyes of 9 patients no remarkable differences of the DFT quotient were noticed comparing a defined area to any other of the same eye as well as to any additional of the fellow-eye, 3. in 52 eyes of 26 patients the scotoma in perimetry was confirmed by a pathological DFT quotient concerning the first eye and 4. within 26 fellow-eyes - in 8 eyes preperimetric glaucomatous lesions were registered by using this stimulation and analysing technique. In the control group of healthy volunteers no pathological DFT quotient had been registered. Conclusion: Glaucoma suspects followed off therapy generally require close follow-up. The DFT-quotient 1H/BW may have the possibility and the potential to detect early - even preperimetric - glaucomatous lesions in a more precise way than other assessment techniques like the HRT will do. Follow-up studies have to reveal the development of the preperimetric glaucoma suspects - especially in that groups presenting with a normal IOP as the patients with NTG and LTG do.
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