Assessment of visual function in glaucoma: a report by the American Academy of Opthalmology

Methodological quality of the review: Low confidence

Author: Jampel HD, Singh K, Lin SC, Chen TC, Francis BA, Hodapp E, Samples JR, Smith SD

Geographical coverage: Not specified

Sector: Glaucoma

Sub-sector: Assessment of visual function

Equity focus: 12 years of age and older

Review type: Other review

Quantitative synthesis method: Narrative/thematic synthesis

Qualitative synthesis method: Not applicable

Background: There is a need to understand how well automated tests of the visual field detect glaucomatous damage or detect the progression of glaucoma, and what new testing strategies are under development and show promise.

Objectives: To review the published literature, and summarise and evaluate the effectiveness of visual function tests in diagnosing glaucoma and in monitoring progression.

Main findings: A total of 85 studies were included in the review. One study was rated as level I evidence. The remaining articles were classified broadly as providing level II evidence. Studies deemed to provide level III evidence were not included in the assessment.

Based on the information of included studies, authors noted that standard white-on-white automated perimetry remains the most commonly performed test for assessing the visual field, with the Swedish interactive threshold algorithm (SITA) largely replacing full-threshold testing strategies. Frequency-doubling technology and its refinement into Matrix perimetry, as well as short-wavelength automated perimetry, now available with SITA, have been evaluated extensively.

Machine learning classifiers seem to be ready for incorporation into software to help distinguish glaucomatous from non-glaucomatous fields. Other technologies, such as multifocal visual-evoked potential and electro-retinography, which were designed as objective measures of visual function, provide testing free of patient input, but issues prevent their adoption for glaucoma management.

Based on findings, authors concluded that advances in technology and analytic tools over the past decade have provided us with more rapid and varied ways of assessing visual function in glaucoma, but they have yet to produce definitive guidance on the diagnosis of glaucoma or its progression over time.

Methodology: PUBMED and Cochrane Library databases were searched for relevant articles from January 1 1994 to May 7 2010. The following search terms were used: visual fields, perimetry, standard, automated, short wavelength, frequency doubling technology, high pass resolution, motion, multifocal electroretinogram, algorithms, image processing, computer-assisted, computer simulation, glaucoma and ocular hypertension.

The search was limited to studies of persons 12 years of age and older, and those in the English language. The titles and abstracts were reviewed by the first author and 185 articles were selected. These articles were further reviewed by the panel members, who determined that 85 met inclusion criteria. Data was abstracted and the panel methodologist assigned a level of evidence to each of the selected articles using a rating scale based on one developed by the Centre for Evidence-Based Medicine.

Applicability/external validity: No methods were used either to assess the applicability/external validity of the results or to discuss how generalizable the results are.

Summary of quality assessment: Authors conducted a narrative synthesis of the findings and appropriately reported inclusion/exclusion criteria used for study selection. However, this review had some important limitations. The authors did not avoid publication and language bias in the search as articles written in English only were included in the review. Authors did not report methods used to select studies and to extract data of included studies, nor did they discuss the quality and risk of bias of included studies. Therefore, there is low confidence in the conclusions about the effects of this study.