The PUPIL Study - Automated, Quantitative Pupil Assessment Using Binocular OCT

Binocular OCT has the potential to allow for objective, quantitative measurement of pupillary reflexes, that can be performed in a fast, safe, and automated manner. Importantly, binocular OCT pupillometry can be performed alongside binocular retinal OCT imaging in a single testing session, in an automated manner (imaging of the retina using OCT is the commonest ophthalmic imaging procedure worldwide - in 2011, it is estimated that more than 20 million retinal OCT images were obtained, more than the sum of all other ophthalmic imaging procedures combined).

Assessment of pupillary reflexes is an essential component of a comprehensive ocular examination. In patients with visual loss, for example, detection of an RAPD often indicates the presence of serious ophthalmic diseases, such as optic neuropathies or severe retinal disease. As such, RAPD testing is essential as a screening test in the assessment of patients with less serious conditions such as cataract.

RAPD testing is commonly performed using the swinging flashlight method (SFM). A positive SFM test suggests the presence of asymmetric damage involving the afferent limb of the pupillary light reflex pathway. The SFM is a qualitative test, and relies upon visualising no pupillary constriction or immediate or delayed pupillary dilation; if either of these responses is observed, an RAPD is believed to be present. The SFM requires a trained examiner and many potential sources of error may confound the results, including anisocoria, off-axis pupil illumination, and unequal retinal bleaching. Pupil abnormalities may be subtle and easily missed using the SFM.

Automated pupilometers allow examiners to precisely and objectively quantify the pupillary response to light by measuring parameters such as minimum and maximum pupil diameter, the amplitude of constriction, latency of constriction, velocity of constriction, and duration of maximum constriction. Dedicated pupillometry devices are commercially available and have been shown to be highly sensitive and specific for RAPD detection e.g. RAPDx; Konan Medical USA, Inc., Irvine, CA. These devices are also capable of detecting the presence of more subtle RAPD, typically not found using the SFM, in diseases such as glaucoma.

Unfortunately, automated pupilometers such as the Konan RAPDx system are not widely used in clinical practice. This is largely because they are expensive devices, limited to a single purpose. A binocular OCT system that could perform both automated pupillometry and retinal OCT imaging would thus have great clinical utility.

Inclusion criteria

for participants with eye disease will include:

• Presence of RAPD as measured with RAPDx
• Presence of retinal disease, glaucoma or neuro-ophthalmic conditions that affect the optic nerve
• Male or female, aged 18 years or older
• Ability to understand nature/purpose of the study and to provide informed consent
• Ability to undergo binocular OCT imaging
• Ability to follow instructions and complete the study
• Ability to speak English

Exclusion criteria

for participants with eye disease will include:

• Optical media opacity sufficient to preclude adequate ocular imaging with OCT
• Ptosis (drooping of the upper eyelid) sufficient to preclude visualization of the pupils using OCT
• Significant pupil irregularity that precludes reliable measurement of RAPD
• Any condition that is likely to interfere with pupillary constriction (e.g., iris pathology)
• Hearing impairment sufficient to interfere with hearing instructions
• Any condition which, in the investigator's opinion, would conflict or otherwise prevent the subject from complying with the required procedures, schedule, or other study conduct.

Inclusion criteria

for healthy subjects will include:

• No self-reported ocular history (although wearing corrective prescription glasses is permitted)
• Male or female, aged 18 years or older
• Ability to understand nature/purpose of the study and to provide informed consent
• Ability to undergo binocular OCT imaging
• Ability to follow instructions and complete the study
• Ability to speak English

Exclusion criteria

for healthy subjects will include:

• Presence of ocular pathology, including ptosis or pupil irregularities
• Hearing impairment sufficient to interfere with hearing instructions
• Any condition which, in the investigator's opinion, would conflict or otherwise prevent the subject from complying with the required procedures, schedule, or other study conduct.