Normative Data Collection Study of the Zilia Ocular for the Measurement of Oxygen Saturation in the Retina

Normative Data Collection Study of the Zilia Ocular for the Measurement of Oxygen Saturation in the Retina

Mainstream oximetry devices use two-wavelength systems to photograph the retina and estimate the oxygen saturation levels in the retinal vessels by comparing light absorption in the blood of the vessels at the selected wavelengths. This method limits the measurements to large retinal vessels, depends heavily on calibration and is non-reproducible across machines. The few numbers of wavelengths used (two) also makes it very susceptible to noise (such as cataract). These shortcomings have largely limited the use of retinal oximetry in clinical practice.

A new technology for retinal oximetry has recently been developed to address issues of dual-wavelength oximeters. Zilia Ocular's oximetry machine uses multi-wavelengths of light to take continuous oxygenation measurements of any targeted regions of the retina. It can measure any area of the retina, including the blood vessels, retinal tissues and the optic nerve head. Its multi-wavelength design also allows it to be less susceptible to noise, more precise and reproducible. This technology has the potential to extend our understanding of retinal pathologies, serve as a new marker for retinal health and even be used as a diagnostic tool to detect retinal injuries before they become visible.

Zilia's novel technology is one of its kind, allowing continuous and accurate measurements of the retina's oxygen saturation. In order to apply this technology to study and investigate retinal diseases, we need to first examine its performance in normal eyes and build a normative database as a reference. Thus, the purpose of the current study is to build a database of baseline oximetry values in healthy Caucasian subjects. The reproducibility of the measurements will also be studied in a subset of patients.

STUDY OBJECTIVES

Objectives

Primary:

1. To measure the oxygen saturation at different locations on the retina (macula, optic nerve head, nasal retina) in order to provide the range of these values in normal eyes.

Secondary:

1. To assess the repeatability of the device's measurements (on a subset of patients).
2. To assess the variability of measurements between the two eyes (on a subset of patients).

Outcomes

Primary Outcome:

1. Normative values of the retinal oxygen saturation at different locations on the retina.

Secondary Outcomes:

1. Intraclass correlation coefficient of the measurements on the same patient at the same visit.
2. Percent difference between the measurements of the two eyes.

STUDY HYPOTHESES

Primary:

1. Oxygen saturation should have a consistent range among healthy subjects.

Secondary:

1. Intraclass classification (ICC) between two measurements on the same eye of the same participant should be at least 90%.
2. Measurements between the two eyes should have a percent difference less than 5%.

STUDY DESIGN

Type of study: single-center.

Expected number of subjects:

For primary objective: N=120 subjects For secondary objective #1: n= 62 For secondary objective #2: n= 12

Inclusion Criteria:

• Adult patients above 18 years old, able to consent and willing to undergo mydriasis.
• Caucasian descent.
• Intraocular pressure ≤ 21 mmHg.
• Normal ophthalmological exam.

Exclusion Criteria:

• Any history of systemic disease, which could affect the eye or oxygen levels (eg: diabetes, severe cardiovascular or respiratory disease).
• History of epilepsy.
• Prior intraocular surgery (except cataract surgery).
• Any history or signs of retinal or optic nerve diseases.
• Pregnancy, or breastfeeding.
• Familial history of glaucoma.
• Ametropia > 6 Diopters.
• Pupil dilation < 3.6 mm.
• Current smoker.