Switching patients with glaucoma to SITA Faster may improve test performance
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Transitioning from SITA Standard to SITA Faster may improve visual field performance in moderate to advanced glaucoma but may conceal disease progression, according to a retrospective, longitudinal study.
The study, published in Ophthalmology, assessed eyes with glaucoma to determine the effect of switching from Swedish Interactive Thresholding Algorithm (SITA) Standard to SITA Faster on visual field (VF) performance in a large range of glaucoma severity.
“We found that eyes that transition from SITA Standard to SITA Faster in a real-world clinical setting, on average, demonstrate an improvement in VF performance (MD) depending on disease severity,” Alex T. Pham, BS, and colleagues wrote. “In particular, eyes that have moderate and severe disease demonstrate a greater increase in MD when transitioned to SITA Faster compared with eyes that have mild disease, which, on average, demonstrate no change.”
The study included 766 eyes of 421 patients at the Wilmer Eye Institute Glaucoma Center of Excellence between 2018 and 2020. Researchers used a temporal sequence of testing strategies, which consisted of two SITA Standards followed by SITA Faster, with a mean time of 13.9 months between each test to “investigate the effect of testing sequence on eye-level VF performance for different stages of glaucoma severity.”
Mean deviation (MD) between the second and first VF in the sequence, either Standard-Standard or Standard-Faster, was studied to detect significant longitudinal deterioration.
SITA-Faster was 52.91% shorter than SITA Standard.
There was 0.87 dB improvement in MD change with Standard-Faster compared with Standard-Standard in eyes with moderate glaucoma and an improvement of 1.49 dB in eyes with advanced glaucoma. There was no significant difference in mild glaucoma.
There were more false positive errors seen in SITA Faster (6.82%) compared with SITA Standard (4.81%; P < .01) as well as more seeding point errors in SITA Faster (39.03%) compared with SITA Standard (27.28%; P < 01).
“Our results indicate that transitioning from SITA Standard to SITA Faster is associated with improved VF performance in eyes with moderate and advanced glaucoma but no difference in VF performance in eyes with mild glaucoma,” Pham and colleagues wrote. “Overall, changing testing strategies from SITA Standard to SITA Faster may obscure the detection of worsening disease in those with more severe stages of glaucoma at baseline, and clinicians should consider this effect when implementing this transition.”
Perspective
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Automated visual field (AVF) testing was introduced nearly 50 years ago, and it remains the cornerstone of assessing functional loss in the management of glaucoma today. Contemporary automated perimetry leverages novel testing strategies and powerful statistical packages to minimize testing time, maximize accuracy and precision, and facilitate the detection of disease progression. In view of the importance of the latter, it is critical that clinicians appreciate factors that may confound the recognition of change over time.
Pham and colleagues have demonstrated that the transition from SITA-Standard to -Faster halves testing time, but at the expense of an “improvement” in MD that may mask increasing VF loss. Moreover, this is most pronounced in patients with more advanced glaucoma, where overlooking progression can have significant ramifications.
In a world increasingly dominated by objective imaging, AVF testing and functional progression analyses remain invaluable. However, practitioners would be wise to recognize idiosyncrasies – including but not limited to the influence of logarithmic scales, VF index ceiling effects in early disease, instability in advanced disease, the relative central field under-sampling and the subtle but important differences between thresholding algorithms – that can impact the detection of functional loss and its progression across the glaucoma continuum.
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