CompletedPhase 4ACTRN12623000297628

Exploring the potential of pupil-dilating and pupil-constricting eye drops as a treatment for presbyopia

Investigating the role of mainstream Pharmacological agents in the Regulation of the Optical Properties of the in vivo human ocular Lens (PROPeL) study

Sponsor

The University of Auckland

Enrollment

20 participants

Start Date

Jun 13, 2023

Study Type

Interventional

Conditions

Presbyopia

Summary

Presbyopia is the loss of the eye’s near focusing ability with age. Most people begin to notice the symptoms of presbyopia at 40-50 years old, when they start experiencing difficulty reading small print. For this reason, people usually have to rely on reading glasses (or some other form of optical correction) to see near objects clearly from middle-age onwards. Presbyopia is believed to be due to a ‘stiffening‘ of the crystalline lens inside the eye with age. Because of this, the lens can no longer change its shape to help our eye change its focus from distance to near objects. The lens is thought to get stiffer because of failure to properly circulate water and important nutrients to protect its proteins against damage. Recently, animal research studies have shown that it is possible to regulate the water and nutrient circulation around the lens using pharmacological agents which are found in eye drops commonly used during eye examinations. This raises the question of whether these eye drops have the potential to be used as a treatment for delaying or preventing the onset of presbyopia. The goal of this study therefore is to use magnetic resonance imaging (MRI) to assess whether water circulation and protein distribution in the lens changes when commonly-used diagnostic eye drops are instilled into the eye. The results of this study will inform us on future strategies for developing new treatments for presbyopia, and alleviate our reliance on reading glasses.

Eligibility

Sex: Both males and femalesMin Age: 18 YearssMax Age: 55 Yearss

Inclusion Criteria1

Healthy adults who are willing and able to provide written informed consent for study participation.

Exclusion Criteria5

Significant refractive error, defined as over 6 Dioptres of myopic or hyperopic mean sphere refractive error
History of ocular pathology or intraocular surgery that has the potential to affect the participant’s vision at the time of study participation
A personal or family history of epilepsy or seizures, neurological disorders/ disease, or serious head injury and/or skull fracture, as these may affect performance in MRI procedures involving viewing flickering visual patterns (e.g. epilepsy) and/or lying still for an extended period of time (e.g. claustrophobia)
Having metal implants (e.g. a cardiac pacemaker) or other contraindications that would put the safety of the participant at risk when undergoing an MRI scan
Pregnant or breastfeeding women, as safety of the eye drops used in this study has not been established for use in pregnancy and lactation. For this reason, participants who become pregnant during the study will also not be able to continue participation.

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Interventions

Eye drops that relax the ciliary muscle (i.e. pupil-dilating eye drops) will be instilled in young participants (those aged between 18 and 40 years old). These include: Tropicamide 10 mg/mL (1%) and/or Cyclopentolate hydrochloride 10 mg/mL (1%). Eye drops that contract the ciliary muscle (i.e. pupil-constricting eye drops) will be instilled in participants with presbyopia (those aged over 40 years old). These include: Pilocarpine hydrochloride 10 mg/mL (1%) or 12.5 mg/mL (1.25%). The ability of the ciliary muscle to contract or relax is dependent on age, hence instillation of different eye drops to induce different ciliary muscle behaviour in young vs. middle-aged participants is required. Amongst the eye drops listed for each age group, which one a participant receives is personalised according to how pigmented their iris is, as iris pigmentation is a factor that influences the time to onset, duration of action, and recovery period of these eye drops. Grading of iris pigmentation and subsequent allocation of eye drops will be done by an NZ-registered optometrist who is a named study investigator at the initial study visit. Participants will have 1 drop of their allocated eye drops administered into each eye at two out of three study visits by an NZ-registered optometrist who is a named study investigator. The first study visit involves an optometric examination and will be between 1 and 1.5 hours long. It includes a general assessment of vision and eye health, baseline measurements of study parameters, instillation of eye drops, and then repeat measurement of study parameters 30-60 min after eye drop administration. The second and third study visits involve an MRI scan to obtain measures of study parameters. The first MRI scan (i.e. the second study visit) will be to obtain baseline measurements. The second MRI scan (i.e. the third study visit) will be performed 30-60 min after eye drop instillation to remeasure the same study parameters. Each MRI scan will take approximately 30-45 mins. All study visits will be conducted on separate days but with no specific time interval between visits required. However, all 3 visits must be completed within 6 to 8 weeks of the first study visit.