Open Access Research article

Frequency doubling technology, optical coherence technology and pattern electroretinogram in ocular hypertension

Mauro Cellini*, Pier Giorgio Toschi, Ernesto Strobbe, Nicole Balducci and Emilio C Campos

Author affiliations

Department of Specialistic Surgery and Anesthesiology Science, Ophthalmology Service, University of Bologna, Via Palagi 9, Bologna, Italy

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Citation and License

BMC Ophthalmology 2012, 12:33  doi:10.1186/1471-2415-12-33

Published: 1 August 2012



To assess which of three methods, namely, optical coherence tomography (OCT), pattern electroretinogram (PERG) or frequency-doubling technology (FDT), is the most sensitive and specific for detecting early glaucomatous damage in ocular hypertension (OH).


Fifty-two patients with OH (24 men and 28 women, mean age of 56 ± 9.6 years) with an intraocular pressure (IOP) > 21 mmHg and fifty-two control patients (25 men and 27 women, mean age of 54.8 ± 10.4 years) with IOP < 21 mmHg, were assessed. All the patients had normal visual acuity, normal optic disk and normal perimetric indices.

All subjects underwent OCT, FDT and PERG. Data were analyzed with unpaired t-tests, Chi-square test and Receiver Operating Characteristic (ROC) curve analyses.


In patients with OH, OCT showed retinal nerve fiber layer (RNFL) thinner than in control group in the superior quadrant (130.16 ± 10.02 vs 135.18 ± 9.27 μm, respectively; p < 0.011) and inferior quadrant (120.14 ± 11.0 vs 132.68 ± 8.03 μm; p < 0.001). FDT showed a significantly higher pattern standard deviation (PSD) (3.46 ± 1.48 vs 1.89 ± 0.7 dB; p < 0.001). With respect to PERG, only the amplitude showed significant differences (p < 0.044) between the two groups. ROC curve analysis revealed a sensitivity and specificity of 92% and 86%, respectively, for FDT-PSD (with an area under the ROC curve of 0.940), whereas with OCT, a sensitivity of 82% and a specificity of 74% was recorded in the inferior RNFL quadrant (with an area under the ROC curve of 0.806) finally with PERG amplitude we found a sensitivity of 52% and specificity of 77% (with an area under the ROC curve of 0.595).


FDT is the most sensitive and specific method for detecting early glaucomatous damage in eyes with OH, and together with OCT, can be useful in identifying those patients who may develop glaucoma.

Trial registration

ISRCT number: ISRCTN70295497

Frequency-doubling technology; Ocular hypertension; Optical coherence tomography; Pattern electroretinogram; Retinal ganglion cells; Retinal nerve fiber layer