Condition category
Eye Diseases
Date applied
Date assigned
Last edited
Retrospectively registered
Overall trial status
Recruitment status
No longer recruiting

Plain English Summary

Lay summary under review 3

Trial website

Contact information



Primary contact

Dr Mauro Cellini


Contact details

Via Dagnini 28

Additional identifiers

EudraCT number number

Protocol/serial number

FDT OH-06-10

Study information

Scientific title

Frequency doubling technology, optical coherence technology and pattern electroretinogram in ocular hypertension: an observational study


Study hypothesis

Glaucoma is an optic neuropathy with the progressive loss of ganglion cells and consequent visual field alterations. The appearance of alterations in the retinal nerve fiber layer represents an early sign of glaucoma damage that precedes the changes in the optic nerve and peripheral alterations.

The quantitative investigation techniques used for the study of the retinal nerve fiber layer (RNFL) are Scanning Laser Polarimetry (SLP), Heidelberg Retinal Tomography (HRT) and, more recently, Optical Coherence Tomography (OCT). OCT makes it possible to examine high resolution cross-sections of ocular tissues using the low coherence interferometry principle and seems more reliable than SLP and HRT in the study of the RNFL.

Due to irreversible nature of the retinal ganglion cell loss and axonal damage, it is particularly important to use high quality investigation techniques for study of glaucoma patients to facilitate early detection of functional deterioration. The qualitative analysis methods currently available are Standard Achromatic Perimetry (SAP) and the more sensitive Short Wavelength Automated Perimetry (SWAP) as well as the recent Frequency-Doubling Technology (FDT) perimetry. The Pattern Electroretinogram (PERG) was introduced 25 years ago to discriminate between healthy and glaucomatous eyes as it records the electrical potentials of retinal ganglion cells and ganglion cell damage is the main cause of the decrease in visual sensitivity in glaucomatous eyes.

Study aim:
To assess which of three methods (Optical Coherence Tomography (OCT), Pattern Electroretinogram (PERG) and Frequency-Doubling Technology (FDT) is the most sensitive and specific for detecting early glaucomatous damage in ocular hypertension (OH).

Ethics approval

Local Ethics Committee of the S. Orsola-Malpighi Hospital, Bologna 26/06/2011 ref: FDT OH-06-10

Study design

Retrospective observational study

Primary study design


Secondary study design

Randomised controlled trial

Trial setting


Trial type


Patient information sheet

Not available in web format, please use the contact details below to request a patient information sheet


Ocular hypertension


All patients underwent:
1. An ophthalmologic examination including visual acuity and applanation IOP assessment
2. Ccorneal radius curvature measurement with automated keratometry (RK, Canon Inc., Tokyo, Japan)
3. Corneal thickness evaluation with a Tomey SP3000 pachymeter (Tomey Corp., Nagoya, Japan)
4. Biomicroscopy of the anterior and posterior segment with automatic measurement of the C/D area ratio of the optic nerve head with OCT3 (Zeiss-Humphrey, Dublin, CA).
5. Standard achromatic perimetry was also performed (SAP) with a Humphrey Field Analyzer-30.2 full threshold program (Zeiss-Humphrey, Dublin, CA)
6. Assessment of the RFNL with OCT3 (Zeiss-Humphrey, Dublin, CA)
7. Frequency-doubling technology (FDT) perimetry with RFA (Zeiss-Humphrey, Dublin, CA) 8. Pattern electrinogram (PERG) with an EREV2000 system (LACE Instruments, Pisa, Italy)

Intervention type



Not Applicable

Drug names

Primary outcome measures

1. The latest generation OCT3 (Zeiss-Humphrey, Dublin, CA) was used to assess and measure the thickness of the peripapillary retinal fiber layer
2. Using the RNFL Thickness Average program, which performs three consecutive, circular scans, each one 3.4 mm in diameter centred around the optic nerve
3. The thickness of the fibers was defined as the number of pixels obtained between the anterior and posterior RNFL projection
4. The values obtained with each scan are shown in graphic form, resembling a clock face divided into four quadrants, representing the superior, nasal, inferior and temporal sections of the RNFL expressed in microns
5. Frequency-doubling technology (FDT) perimetry is a new technique designed for the rapid and effective identification of visual field impairment due to glaucoma. The FDT stimulus consists of a bar grid with a low frequency spatial sinusoidal profile (0.25 cycles/degree) subjected to a sinusoidal temporal commutation at a frequency of 25 Hz. For each visual field we evaluated the mean defect (MD) and the pattern standard deviation (PSD).
6. For PERG recording we followed ISCEV standard guideline. The PERG stimulus was a black and white checherboard of 1.6 cycles/degree with a contrast of 99%, four reversal/s and a mean luminance of 110 cd/m2. The transient PERG response was characterized by three subsequent peaks that in normal subjects are indicated on the basis of polarity and latency: N35, P50 and N95.
7. All statistical analyses were performed using the FASTAT Version 2 program package (Systat Inc., Evanston, Illinois) using the Student t test for unpaired data and Bonferroni correction, assuming p < 0.01 as significant
8. The Chi-square test was used for categorical data
9. The Bartlett correlation test was used to assess any correlation between thinning of the RNFL and alterations in the FDT indexes with IOP and the hemodynamic indices
10. Finally, Receiver Operating Characteristic (ROC) curve analysis was performed to determine the diagnostic sensitivity and specificity of OCT, FDT and PERG

Secondary outcome measures

Data of OCT, FDT and PERG of ocular hypertensive patients were compared to healthy controls

Overall trial start date


Overall trial end date


Reason abandoned


Participant inclusion criteria

1. 52 patients aged between 44 and 76 years (mean 56±9.6), with an intraocular pressure (IOP) greater than 21 mmHg (mean 23.96±1.3)
2. A control group consisted of 55 subjects aged between 42 and 75 years (mean 54.8±10.4)

Participant type


Age group




Target number of participants

52 patients and 55 controls healthy subjects

Participant exclusion criteria

1. Previous history of eye surgery
2. Previous history of ocular inflammation
3. Previous hystory of systemic diseases

Recruitment start date


Recruitment end date



Countries of recruitment


Trial participating centre

Via Dagnini 28

Sponsor information


University of Bologna (Italy)

Sponsor details

Via Palagi
+39 (0)51 34 14 50

Sponsor type




Funder type


Funder name

University of Bologna (Italy)

Alternative name(s)

Funding Body Type

Funding Body Subtype


Results and Publications

Publication and dissemination plan

Not provided at time of registration

Intention to publish date

Participant level data

Not provided at time of registration

Results - basic reporting

Publication summary

1. 2012 results in

Publication citations

  1. Results

    Cellini M, Toschi PG, Strobbe E, Balducci N, Campos EC, Frequency doubling technology, optical coherence technology and pattern electroretinogram in ocular hypertension., BMC Ophthalmol, 2012, 12, 33, doi: 10.1186/1471-2415-12-33.

Additional files

Editorial Notes