RecruitingACTRN12625000542493

Can eye drops safely replace reading glasses in older adults? A short-term study.

Investigating the physiological effects of acute pilocarpine use for presbyopia treatment on posterior ocular structures

Sponsor

The University of Auckland

Enrollment

24 participants

Start Date

Aug 25, 2025

Study Type

Interventional

Conditions

Retinal ischemia Presbyopia

Summary

Everyone who reaches middle age will eventually need reading glasses due to an age-related eye condition known as presbyopia. Recently, Vuity eye drops (pilocarpine 1.25%) have emerged as an effective treatment for the blurry near vision that comes with presbyopia. However, the safety concerns that accompany this treatment have not yet been adequately addressed. This research aims to determine whether acute administration of Vuity eye drops can change choroidal thickness, choroidal blood flow, or retinal function. We will examine whether any physiological changes to the choroid or retina occur synergistically with uncorrected retinal defocus, resulting from pupil constriction or direct stimulation of the choroid and retina.

Eligibility

Sex: Both males and femalesMin Age: 40 YearssMax Age: 55 Yearss

Plain Language Summary

Simplified for easier understanding

As we get older, most of us eventually need reading glasses — a very common condition called presbyopia, where the eye's natural lens loses its flexibility and close-up objects become blurry. A relatively new treatment called Vuity eye drops (pilocarpine 1.25%) has shown promise in temporarily improving near vision by slightly constricting the pupil, which can sharpen focus without glasses. This short-term study aims to better understand whether Vuity eye drops are safe and whether they cause any changes to the blood flow or tissue at the back of the eye (called the choroid and retina). Researchers are interested in whether these changes, if any, happen because of the pupil constriction or through a more direct effect on eye tissue. You might be eligible if you are between 40 and 55 years old, are generally healthy, and only use glasses or contacts for reading (presbyopia). People with certain eye conditions, narrow eye angles, known allergies to pilocarpine, or those taking specific medications affecting vision or eye pressure would not be able to join this study.

This summary was AI-generated to explain the trial in plain language. It is not medical advice. Always discuss eligibility with your doctor before enrolling in a clinical trial.

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Interventions

This is an interventional study that will investigate Vuity eye drops' (pilocarpine 1.25%) mechanism of action on the choroid and retina, as the first step towards ensuring this treatment is safe for

This is an interventional study that will investigate Vuity eye drops' (pilocarpine 1.25%) mechanism of action on the choroid and retina, as the first step towards ensuring this treatment is safe for long-term use. The aim of this study is to understand whether acute pilocarpine administration can change choroidal thickness, choroidal blood flow, or retinal function. We hypothesise that this occurs via 3 mechanisms: 1/ by failing to correct retinal defocus, 2/ by constricting the pupil, or 3/ by directly stimulating muscarinic receptors within the choroid and retina. Each participant will participate in 3 controlled experiments to understand whether acute administration of Vuity eye drops (pilocarpine 1.25%) can act directly or indirectly on the choroid and retina. Participants will receive 1 drop of Vuity in the experimental eye during each of the 3 study visits. - Experiment 1 will examine whether pilocarpine changes the physiology of the choroid and retina, independently from hyperopic defocus. In this experiment, participants will first undergo a 20-minute stabilisation period by watching a movie at a far viewing distance (6 m). After stabilisation, baseline measures of retinal and choroidal thickness and blood flow (using optical coherence tomography, OCT) and retinal function (using global flash multifocal electroretinography, gmfERG) will be acquired, with participants' eyes fully corrected for any hyperopic defocus. After baseline measures are completed, 1 drop of Vuity (pilocarpine 1.25%) is administered by a study researcher to the participants' experimental eye. Participants will then undergo 60-min stabilisation period by watching a movie at a far viewing distance (6 m) to allow pilocarpine to reach maximal effect in the eye, before measures of retinal and choroidal thickness and blood flow are repeated. - Experiment 2 will examine whether pilocarpine changes the physiology of the choroid and retina independently from both hyperopic defocus AND retinal illuminance (determined by pupil size). In this experiment, 1 drop of tropicamide (1%) will first be instilled by a study researcher to both eyes of the participant to control for pupil size and therefore retinal illuminance. Participants will then undergo a 20-minute stabilisation period by watching a movie at a far viewing distance (6 m). After stabilisation, baseline measures of retinal and choroidal thickness and blood flow (using optical coherence tomography, OCT) and retinal function (using global flash multifocal electroretinography, gmfERG) will be acquired, with participants' eyes fully corrected for any hyperopic defocus. After baseline measures are completed, 1 drop of Vuity (pilocarpine 1.25%) is administered by a study researcher to the participants' experimental eye. Participants will then undergo 60-min stabilisation period by watching a movie at a far viewing distance (6 m) to allow pilocarpine to reach maximal effect in the eye, before measures of retinal and choroidal thickness and blood flow are repeated. - Experiment 3 will examine whether pilocarpine changes the physiology of the choroid and retina by subjecting the eye to sustained periods of hyperopic retinal defocus, independently of retinal illuminance (determined by pupil size). In this experiment, 1 drop of tropicamide (1%) will first be instilled by a study researcher to both eyes of the participant to control for pupil size and therefore retinal illuminance. Participants will then undergo a 20-minute stabilisation period by watching a movie at a far viewing distance (6 m). After stabilisation, baseline measures of retinal and choroidal thickness and blood flow (using optical coherence tomography, OCT) and retinal function (using global flash multifocal electroretinography, gmfERG) will be acquired, with participants' eyes fully corrected for any hyperopic defocus. After baseline measures are completed, 1 drop of Vuity (pilocarpine 1.25%) is administered by a study researcher to the participants' experimental eye. Participants will then undergo 60-min stabilisation period by watching a movie at a near viewing distance (30 cm) to subject the eyes to hyperopic defocus while allowing pilocarpine to reach maximal effect in the eye, before measures of retinal and choroidal thickness and blood flow are repeated. Each experiment is anticipated to take 2 hours (total ~6 hours for the study). The 3 experiments will be conducted across 3 separate study visits, spaced at least 24 hours apart to ensure no carryover effects from the previous visit. Each experiment will be performed at the same time of day (±1 hour) to control for known diurnal variations in choroidal thickness. A random number generator will be used to randomise the experimental eye and the order of experiments for each participant.