Abstract
AimsTo evaluate Compass, a new instrument for glaucoma screening and diagnosis that combines scanning ophthalmoscopy, automated perimetry, and eye tracking.Materials and MethodsA total of 320 human subjects (200 normal, 120 with glaucoma) underwent full ophthalmological evaluation and perimetric evaluation using the Humphrey SITA standard 24° test (HFA), and the Compass test that consisted of a full-threshold program on the central 24° with a photograph of the central 30° of the retina. A subgroup of normal subjects and glaucoma patients underwent a second Compass test during the same day in order to study test-retest variability. After exclusion of 30 patients due to protocol rules, a database was created to compare the Compass to the HFA, and to evaluate retinal image quality and fixation stability.ResultsThe difference in mean sensitivity between Compass and HFA was -1.02 ± 1.55 dB in normal subjects (p<0.001) and -1.01 ± 2.81 dB in glaucoma (p<0.001). Repeatability SD for the average sensitivity was 1.53 for normal subjects and 1.84 for glaucoma. Test time with the Compass was 634±96 s (607±78 for normals, 678±108 for glaucoma). Compass analysis showed the percentage of fixation within the central 1° was 86.6% in normal subjects, and 79.3% in glaucoma patients. Color image quality was sufficient for diagnostic use in >65% of cases; Image-based diagnosis was in accordance with the initial diagnosis in 85% of the subjects.ConclusionsBased on preliminary results, Compass showed useful diagnostic characteristics for the study of glaucoma, and combined morphological information with functional data.
Highlights
Glaucoma is the leading cause of irreversible blindness with a prevalence of 3.5% in the population aged 40–80 years
Compass analysis showed the percentage of fixation within the central 1° was 86.6% in normal subjects, and 79.3% in glaucoma patients
The diagnosis of glaucoma relies on the assessment of intraocular pressure (IOP) and its confounding factors, as well as specific changes occurring in the visual field (VF), the optic nerve head (ONH), and the retinal nerve fiber layer (RNFL)
Summary
Glaucoma is the leading cause of irreversible blindness with a prevalence of 3.5% in the population aged 40–80 years. Due to the lack of symptoms up to advanced stages and to the limitations of world-wide diagnostic resources and information (so that a high number of subjects are very rarely seen by ophthalmologists in the course of their life), the current undetection rate for the disease is about 50%, even in so-called “developed” countries [2,3]. Perimetry is commonly considered the diagnostic gold-standard for glaucoma progression, as it is a reliable test with a very accurate database, which has been validated over many decades of clinical use. It enables the detection of small glaucomatous changes, which directly impact the visual function of patients. Perimetry is limited by low diagnostic sensitivity in early stages of the disease.[4], and being a psychophysical test, it is influenced by learning, fatigue, psychophysical status, as well as eye movements. [5]
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