Recent developments in perimetry: test stimuli and procedures

Automated perimetry has evolved substantially in recent years, in part due to modern computer technology that enables more complex visual stimuli and test procedures to be realised than those incorporated in traditional white-on-white luminance increment perimetry. This paper reviews briefly a number of advances in automated perimetry. The review includes discussion of new test types: frequency doubling technology perimetry, short wavelength automated perimetry, flicker perimetry, high-pass resolution perimetry and rarebit perimetry. Test algorithms applied to perimetry such as zippy estimation of sequential thresholds (ZEST), Swedish interactive thresholding algorithm (SITA), tendency-oriented perimetry (TOP) and multi-sampling supra-threshold perimetry are also discussed.

Recent developments in automated perimetry in glaucoma diagnosis and management

Recently, there have been several new developments in automated perimetry that have contributed to enhanced diagnosis and management of glaucoma. This paper will briefly review four of the latest advances in automated perimetry: (1) efficient test strategies that reduce the testing time and variability of automated perimetric testing, in particular, the Swedish Interactive Threshold Algorithm (SITA) and Tendency Oriented Perimetry (TOP) test strategies will be described; (2) Frequency Doubling Technology (FDT) perimetry, which has been shown to be a rapid, effective method of detecting glaucomatous visual field loss; (3) Short Wavelength Automated Perimetry (SWAP), which has demonstrated the ability to predict the onset and progression of glaucomatous visual field deficits; (4) The Multifocal Electroretinogram (mfERG) and the Multifocal Visual Evoked Potential (mfVEP), which provide an objective measurement of the visual field. Each of these techniques has presented distinct advantages for the diagnosis and management of glaucoma.

What's new in perimetry

Despite important refinements that have improved quantitation and shortened test time, modern perimetry remains relatively insensitive and plagued by high test-retest variability. Some novel methods, though not yet fully vetted, offer the promise of improving sensitivity and reducing variability.

[Pulsar perimetry. A review and new results]

We present a review and update on Pulsar perimetry, which combines temporal frequency, contrast and spatial frequency stimuli. The effects of age, visual acuity, and learning on results are described. Data on threshold fluctuation, signal-to-noise ratio, and the possibility of reducing noise with filtering techniques are provided. We describe its dynamic range and the possibility of compensating for profound defects. Finally, we show the results obtained in normal patients and in those with ocular hypertension or initial glaucoma, as well as an analysis of glaucoma progression.

Update on the imaging techniques in the diagnosis of diabetic retinopathy

Diabetic retinopathy is one of the leading causes of vision loss worldwide. Fluorescein angiogram still plays a primary role in its diagnosis but new non-invasive technologies as optical coherence tomography, fundus autofluorescence and microperimetry are gaining popularity in the last years. Anatomical changes found with these devices have been widely described but their correlation with visual function needs to be assessed and several features have been proposed as indicators of visual prognosis. The aim of this paper is to give a scope of the actual role of these techniques in the evaluation of retinal impairment secondary to diabetes.

Perimetry, today and tomorrow

Perimetry is clearly in an explosive stage of development. Here, an attempt is made to bring together major developments and put them into an orderly perspective. The projection-bowl-perimeters of Bern and Tübingen set the stage. Standardization provides the base for future development and data exchange. Automation and inclusion of computational procedures enhance the possibility of broad utilization for better screening and advanced testing. New test procedures make possible extremely fine localization of functions and allow superior definition of areas of involvement in pathology. New fundus perimeters make possible instantaneous fine correlations between functional changes and observed retinal anatomic lesions.

[Modern diagnostic methods for suspected glaucoma and glaucoma]

BACKGROUND

Diagnosis of early glaucomatous damage as well as the detection of glaucomatous change are still difficult tasks. During the last years numerous new diagnostic techniques have been investigated and some of them have been introduced to the market.

METHODS

This paper reviews the different aims of diagnostic technologies in the field of glaucoma. Methods appearing suitable for a large-scale use by ophthalmologists will be judged according to their suitability to meet the goals of early diagnosis, objective diagnosis, progression analysis and screening.

CONCLUSIONS

The new diagnostic techniques have not yet greatly influenced our diagnostic procedure. This is mainly due to the fact that, for the most difficult borderline cases of glaucoma, these methods are of limited value, or have not yet been sufficiently investigated. Nevertheless, the Heidelberg retina tomograph (HRT), the nerve fiber analyzer GDX, short wavelength perimetry (SWAP), and the frequency doubling test (FDT) may play a role in these cases. For follow-up, HRT and GDx have proven valuable, especially in early stages of the disease. The very short testing time of FDT together with good specificity qualifies this test for glaucoma screening.

Perimetry update

The possible applications of computer-assisted static perimetry are examined after five years of personal controlled studies of different types of computerized perimeters. The common advantage of all computer-assisted perimeters is the elimination of the influence of the perimetrist on the results. However, some perimeters are fully computer-assisted and some are only partially so. Even after complete elimination of the perimetrist's influence, some physiological and psychological influences remain due to the patient and will cause fluctuations of the results. In perimeters, the density of the grid and the adaptive strategy of exact threshold measurement are important in obtaining reproducible results. A compromise between duration of the test and exactness has to be found. The most acceptable compromise seems to be an uneven distribution of stimuli, which form a denser grid in areas of special interest and a wider grid in areas less likely to be involved, combined with exact threshold measurements only in suspicious areas. Multiple stimulus presentation is not adequate. High sensitivity of screening is not a great advantage, unless combined with a high specificity. We have shown that using the same stimulus luminosity for center and periphery (a nonadaptive strategy) produces nonspecific results. Only an adaptive strategy can result in high sensitivity and specificity. Adaptive strategy means that the luminosity of the stimulus is adapted to the individual threshold curve of the visual field. In addition, the exact individual thresholds are bracketed by small up and down steps of variation in luminosity. In some cases, scanning programs with two levels of adaptation can be sufficient. The user of modern perimeters must understand such terms as: asb, dB, presentation time, and diameter of stimuli. Projection of stimuli is preferred to light emitting diodes or glass fiber optics. The programs (software) of the modern instruments are of the greatest importance, because the clinical experience that the perimetrist had to acquire in previous manual perimetry is incorporated in these programs. In the Octopus perimeter a delta program is available that differentiates patient fluctuations that may be insignificant from directed significant alterations of the field which might require alteration of therapy. The programs are listed for different computer-assisted perimeters, and their choice is described. The costs of the perimeters are also given. Many controlled clinical studies are quoted briefly where they are useful for understanding the discussion. A brief chapter deals with the reliability of the perimetric test.(ABSTRACT TRUNCATED AT 400 WORDS)