Researchers recently evaluated a novel objective perimetry method—multifocal pupillographic objective perimetry—against standard automated perimetry techniques to improve reliability and test-retest variability with methods such as SITA and SITA Faster.
Specifically, the study compared the diagnostic power and test-retest variability (TRV) of multifocal pupillographic objective perimetry (mfPOP) with two standard automated perimetry (SAP methods): Humphrey Field Analyzer (HFA) SITA Fast 24-2 and Matrix Frequency Doubling Technology perimetry. In their article in the Journal of Glaucoma, the investigators described mfPOP as follows: “When appropriate dichoptic multifocal luminance stimuli are used, the 2 pupils provide independent, direct, and consensual responses to every point in the fields of both eyes.” Whereas SAP tests one eye at a time and therefore “confounds test-time and eye”, mfPOP tests both eyes concurrently and offers a “good statistical basis for measuring asymmetries between eyes at each test location.”
Participants were divided into those with glaucoma (40 participants and 80 eyes, including perimetric and preperimetric eyes) and 94 controls who were recruited from optometry practices and academic institutions. mfPOP tests (OFA30 and OFA15) assessed the central ±30 and ±15 degrees of the visual field, generating 30-2 and 10-2 style reports. Each test was repeated two weeks apart to evaluate TRV, and diagnostic power was quantified using area under receiver operating characteristic curves (AUROC).
AUROC values were comparable across methods. mfPOP, HFA, and Matrix were 93% in perimetric eyes and 73% in preperimetric eyes. mfPOP’s diagnostic accuracy was also consistent across sensitivity and delay metrics.
Differences were apparent in testing speed and TRV, however. mfPOP tests were faster than SAP: OFA30 took 4.09 minutes per eye while HFA and Matrix took ~5 minutes per eye. mfPOP demonstrated lower TRV than SAP, especially in damaged fields, and provided additional metrics such as response delays and between-eye asymmetries. The shorter test duration and non-invasive nature of mfPOP improved patient experience and reduced fatigue compared to SAP.
Hypersensitivity was also a strength of OFA, the researchers explained: “OFA hypersensitivity was indicated, possibly reflecting excitotoxicity, which is a feature of glaucoma and could contribute to early-stage disease. When employing threshold perimetry, hypersensitivity is difficult to measure because quantifying it via threshold measures requires test subjects to perform super-human discrimination of tiny contrasts, whereas OFA simply measures a larger neural response.”
The inclusion of novel metrics such as delay data and asymmetry measures allowed clinicians to gain a more comprehensive understanding of glaucomatous damage, and suggests that mfPOP may be integrated into routine practice for early glaucoma detection, monitoring progression, and identifying asymmetries not captured by SAP.
Larger, longitudinal studies are needed to evaluate mfPOP’s utility in tracking glaucoma progression.
A full list of author disclosures can be found in the published research