Octopus 900 perimeter

The same Octopus 900 perimeter (Haag-Streit AG, Switzerland) with G2 pattern of the central 30 degrees VF (phases 1 and 2, which provide doubled threshold determination) and dynamic strategy were applied for all examinations. Current ametropia was corrected for according to the manufacturer's recommendation. Only reproducible tests with <20% false-positive and 20% false-negative response rates were used for evaluation. The software-provided 10 VF cluster MDs were used [14 ] (Figure 1(a)). The clusters of the left eyes were mirrored and numbered the same as those of right eyes.

Annual visits included a complete ophthalmological examination including slit lamp inspection, applanation tonometry, gonioscopy, funduscopy, standardized qualitative and quantitative analyses of color photographs of the optic nerve head, white-on-white standard automated perimetry (SAP). Scanning laser ophthalmoscopy was performed at baseline using the Heidelberg Retinal Tomograph (HRT) for objective measurement of the cup-disc-ratio.
Full threshold measurements (3 phases) were performed with the Octopus 900 perimeter (Haag-Streit, Schlieren, Switzerland) using the G1 pattern that covers the central field up to 30° eccentricity. The first three measurements were excluded from the analyses to mitigate learning effects. Visual field defects were defined as a loss of > 10 dB in one and > 5 dB in at least two adjacent location or as a loss > 10 dB in two adjacent locations.
Using color fundus photographs, ONH morphology was classified according to the criteria by Jonas and coworkers [5 (link)].

An Octopus 900 perimeter (Haag Streit AG, Koeniz, Switzerland) was used to measure contrast thresholds by presenting circular achromatic luminance increments on an achromatic background of 10 cd/m². Experiments were driven by the Open Perimetry Interface (OPI)³² . Fixation was monitored visually, using the instrument’s fixation monitor. A 1:1 staircase and yes/no response criterion were used to determine individual thresholds. Presentation duration was 200 ms, with a square wave temporal profile. Stimuli were consecutively presented to 12 visual field locations (4 locations at each of 12.7°, 21.2°, and 29.7° eccentricity, Fig. 1).Figure 1

Visual field locations tested in the current study. A conventional 24-2 visual field pattern (right visual field), used in clinical visual field tests, is displayed for clinical reference.

The same calibrated Octopus 900 perimeter (Haag-Streit AG, Koeniz-Berne, Switzerland) was used for all tests. The G 2 test of the central 30° visual field (phases 1 and 2, which provide doubled threshold determination) was tested with normal (bracketing) strategy within 3 months from the OCT imaging (typically on the same day). Current ametropia was corrected for according to the manufacturer’s recommendation. Artificial tear drops were given before the 5-minute adaptation period. The right eye was tested first in all cases. Only reproducible tests with less than 20% false positive and 20% false negative response rates were used for evaluation. The manufacturer-provided 10 visual field clusters [23 (link)] were used (Fig 1). The clusters of the left eyes were mirrored and numbered as those of right eyes. For the cluster structure-function investigation the software-provided uncorrected cluster MD values (in dB) were used. In the normal (bracketing) strategy 4.0 dB luminance steps are used to determine the threshold sensitivity, which is refined using 2.0 and 1.0 dB steps. Of the global indices mean sensitivity (MS) and mean defect (MD) were analyzed. In Octopus perimetry the abnormal MD values are positive numbers.

Ophthalmic examination included visual acuity (VA, using Snellen visual acuity charts), color vision (Ishihara plates) and color fundus photography, either 35° (Topcon Great Britain Ltd, Berkshire, UK) or ultra‐widefield (200°) confocal scanning laser imaging (Optos plc, Dunfermline, UK). Fundus autofluorescence was performed with 30 or 55° Spectralis (Heidelberg Engineering Ltd, Heidelberg, Germany), or ultra‐widefield Optos (Optos plc) imaging with excitation wavelength 488 and 532 nm, respectively. Spectral‐domain optical coherence tomography (OCT) scans (Spectralis; Heidelberg Engineering Ltd) and kinetic visual fields (Goldmann or Octopus 900 Perimeter; Haag‐Streit) were performed.
Electrophysiological testing included full‐field and pattern electroretinography (ERG; PERG) and incorporated the International Society for Clinical Electrophysiology of Vision (ISCEV) standards (Mcculloch et al., 2015 (link)). Pattern ERG testing included recordings to standard (15 × 11°) and large (30 × 22°) stimulus fields (Lenassi, Robson, Hawlina, & Holder, 2012 (link))Additional On–Off ERGs (Sustar et al., 2018 (link)) and S‐cone ERGs (Perlman, Kondo, Chelva, Robson, & Holder, 2020 (link)) were performed according to previously described methods (Audo et al., 2008 (link); Georgiou et al., 2019 (link)).