Effect of Defocus in Soft Contact Lenses on Internal Retinal Vascularization

Université de Montréal

Status: Active, not recruiting

Conditions: Nearsightedness

Treatments: Device: Experimental: Myopic defocus soft lens design (MDSL); Device: Active Comparator: Single vision soft lens design (SVSL

Study type: Interventional

Funder types: Other; Industry

Identifiers

NCT06527274

2024-5133

Details and patient eligibility

About

The purpose of this study is to gain a better understanding of the retinal vascular changes that occur in response to the optical effect of a myopic defocus daily disposable soft contact lens (MDSL) in a group of healthy young myopic adults (18-35 years; myopia -1.00D to -4.00D; all genders). It will also learn about the acceptance of this visual correction modality compared to regular contact lenses.

The main questions to be answered are:

• To evaluate changes in retinal blood flow by visualizing retinal vascular density in the superficial and deep plexus after one week of MDSL wear.
• To evaluate changes in choroidal thickness at the macular level after one week of MDSL wear.
• To evaluate the visual comfort provided by this MDSL design using a questionnaire.

Researchers will compare the MDSL to a daily disposable single vision soft lens (SVSL) used to correct myopia to determine if the addition of a defocus area makes a difference in the retinal response to the visual signal.

Participants will be required to

• Wear both MDSL and SVSL for one week each, in a random order.
• Read letters to measure visual acuity
• Have a deep scan of their retina with an optical coherence tomography (OCT) device
• Rate the comfort and vision provided by both devices using a questionnaire.

Full description

Objective:

The aim of this study is to gain a better understanding of the retinal vascular changes that occur in response to the optical effect of a myopic defocus daily disposable contact lens used in another (ongoing) research project (NCT05191134).

The primary objective of the study is to evaluate changes in retinal blood flow by visualizing retinal vascular density in the superficial and deep plexus following one week's wear of a high peripheral add soft contact lens in a population of young myopic adults.

The second objective is to assess changes in choroidal thickness at the macular level after one week's wear of the high peripheral add soft contact lens.

A third objective is to evaluate, through questionnaire, the visual comfort provided by this lens design.

Materials and methods:

25 myopic participants aged between 18 and 35 will be enrolled. Each participant will be randomly fitted with two lenses: a monofocal spherical soft lens (nesofilcon A) for one week and a high-add bifocal soft lens (anti-myopia) for the same duration of time. Participants will be asked to attend three different visits, one week apart.

At visit #1, initial measurements of deep and superficial plexus blood vessel density and choroidal thickness will be taken with an angiographic optical coherence tomograph (OCT-A Triton, Topcon USA).

These measurements will be repeated with other lenses at visit 2 and 3.

The results will be compared. Participants will be asked to evaluate the visual performance of each lens after 1 week of wear through a questionnaire.

Hypothesis: It is expected that one week's wear of the peripheral myopic defocus contact lens will cause an increase in blood vessel density and a thickening of the choroid compared with initial measurements. A decrease in blood vessel density and choroidal thinning is expected after one week's wear of the spherical soft lens (hyperopic defocus), compared with baseline. Both lenses will be well tolerated during daily activities.

Enrollment: 25 estimated patients

Sex: All

Ages: 18 to 35 years old

Volunteers: Accepts Healthy Volunteers

Inclusion criteria

• · Astigmatism ≤ 1.00 D

  • Myopia between -0.50 and -4.00D
  • Aged between 18 and 35
  • Binocular acuity of 6/6 or better

Exclusion criteria

• · Recent intake (< 3 months) of medication affecting blood pressure (e.g. hypotensive, anovulant, CNS stimulant, etc.).

  • Corneal dystrophy or irregularity
  • Use of topical ocular medications
  • Smoking (tobacco or marijuana)
  • Have contraindications to wearing soft contact lenses
  • Being currently under myopia control treatment or had been under control in the last 3 months
  • Being pregnant or breast-feeding
  • History of refractive surgery
  • Addiction to drugs or alcohol

Trial design

Primary purpose: Basic Science

Allocation: Randomized

Interventional model: Crossover Assignment

Masking: Single Blind

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25 participants in 2 patient groups

Myopic defocus soft lens design (MDSL)

Experimental group

Description:

This arm involves the wear of a daily disposable soft contact lens (nesofilcon A) designed with a myopic defocus zone. This is a 14.2mm total diameter lens with a 4.2mm central zone for distance vision correction. This is followed by an abrupt transition zone of 1.2mm with no optical power. Then a higher convex power zone covers the surface to the edge of the optical zone (8mm). The rest of the lens (up to 14.2 mmOAD) supports the lens on the eye surface and has no power nor refractive effect. The power of the add area is calibrated to the central power to achieve a net add power of +5D. For example: -1.00D central power is surrounded by a +6D convex area; -2D is surrounded by a +7D area, and so on.)

Treatment:

Device: Experimental: Myopic defocus soft lens design (MDSL)

Single vision soft lens design (SVSL)

Active Comparator group

Description:

This arm involves the wear of a daily disposable soft contact lens (nesofilcon A) designed as a regular optical device to compensate for refractive error. In the case of this study, this lens will be made available from -1.00D to -4.00D. This lens is already in regular use in the US (K113703) and Canadian markets. Its design includes a central optical zone of 8mm that is powered to correct distance vision. The rest of the lens is supported on the ocular surface and has no power.

Treatment:

Device: Active Comparator: Single vision soft lens design (SVSL