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Glaucoma The Visual Field in Glaucoma Paolo Brusini, 1 Claudia Tosoni 2 and Marco Zeppieri 3 1. Chief of Department of Ophthalmology; 2. Senior Glaucoma Specialist; 3. Junior Glaucoma Specialist, Azienda Ospedaliero-Universitaria ‘Santa Maria della Misericordia’, Udine, Italy Abstract Visual field (VF) testing is currently the most useful technique in both confirming diagnosis and monitoring patients during the follow-up of chronic glaucoma. Relative paracentral scotomas and nasal steps are usually the earliest signs of glaucomatous functional damage. VF damage severity can be assessed by various classification systems, like the Hodapp et al. and Advanced Glaucoma Intervention Study (AGIS) method and the Glaucoma Staging System. Progression can be analysed based on clinical judgment, defect classification systems, trend analysis and event analysis. When standard automated perimetry is within normal limits in suspect glaucoma patients, various non-conventional VF testing techniques can be useful in detecting the first signs of functional damage. These techniques include short-wavelength automated perimetry, frequency doubling technology, flicker automated perimetry and other methods that are still experimental (e.g. motion perimetry, rarebit perimetry and pulsar perimetry). It should be remembered, however, that VF testing, even if automated, is a psycho-physical test with physiological short- and long-term fluctuations, and possible artifacts. Keywords Visual field, glaucoma, standard automated perimetry, non-conventional visual field testing techniques, functional damage Disclosure: The authors have no conflicts of interest to declare. Received: 1 September 2012 Accepted: 25 October 2012 Citation: European Ophthalmic Review, 2012;6(4):222–6 Correspondence: Paolo Brusini, Department of Ophthalmology, Azienda Ospedaliero-Universitaria ‘Santa Maria della Misericordia’, p.le S. Maria della Misericordia 15, Udine 33100, Italy. E: brusini@libero.it Glaucoma was rightly defined as a ‘perimetric disease’. The visual field (VF) examination actually offers the most useful information for defining and quantifying the severity of functional damage. White-on-white standard automated perimetry (SAP), notwithstanding its well-known limits, is still the most commonly used technique for testing the VF in patients affected with chronic glaucoma or suspect glaucoma. The central 30° of the VF are of great importance, which can be explored by methods composed of regular grids with test locations evenly distanced at 6° from each other (30-2 or 24-2 test) or with stimuli that are more densely positioned in the centre (i.e. Octopus G tests), with a white light stimuli of size III. The classic strategy for quantifying VF defects is the full threshold, but the Swedish interactive threshold algorithm (SITA) standard has the same accuracy and takes 30–40 % less time than the former, thus should be currently preferred in all cases. In some cases (i.e. subjects with difficult concentration, elderly patients, etc.), however, fast threshold strategies such as tendency oriented perimetry (TOP) and dynamic, may be preferable, even if these methods offer less precision. Visual Field Defects in Glaucoma The earliest VF defects in glaucoma include clusters of points having slight sensitivity depressions and high threshold fluctuations in the central 20° area (relative paracentral scotomas) and an asymmetric sensitivity along the nasal hemi-meridian (Rønne’s nasal step). 1,2 The blind spot enlargement, which was interpreted in the past as a characteristic sign of early glaucoma damage, is currently considered to be of scarce clinical importance, especially considering that it is often caused by a 222 peripapillary chorioretinal atrophy and/or other non-glaucomatous anomalies of the optic disk. In early glaucoma a significant depression of the pericoecal sensitivity can sometimes be found. 3 A diffuse sensitivity depression that may have a homogenous or heterogeneous distribution, can sometimes be found in the initial phases of glaucoma, especially in young patients with high intraocular pressure (IOP) values. 4 This finding is not very specific and is most commonly due to an incipient cataract; thus should always be carefully evaluated. Modern statistical analysis programmes have greatly improved the interpretation of the VF printout. 5–8 The statistical assessment and comparison of the total and pattern deviation maps, for example, provide useful information in the detection of very small scotoma and can also be helpful in differentiating the various types of damage (e.g. diffuse, localised and mixed). The criteria most commonly used to define a VF as abnormal include the presence of at least one of the following conditions: 9 • glaucoma hemifield test (GHT) outside normal limits in two consecutive tests; • statistically abnormal corrected pattern standard deviation (CPSD) confirmed in at least two consecutive tests; and • a cluster of three or more significantly abnormal (p<5 %) non-peripheral points with at least one with a p<1 % in two consecutive tests. When interpreting a VF printout, it is very important to be aware that several artifacts can affect the test, these include: © TOUCH MEDICAL MEDIA 2012