Related Experiment Video
Updated: Jul 15, 2026
07:06
Binocular Dynamic Visual Acuity in Eyeglass-Corrected Myopic Patients
Published on: March 29, 2022
Contrast visual acuity with bifocal contact lenses
1Ueda Eye Clinic, Shimonoseki, Japan. uedaganka@stellar.meon.ne.jp
Eye & Contact Lens
|May 15, 2007
Summary
Bifocal rigid gas-permeable contact lenses offer superior visual performance for presbyopia compared to soft bifocal lenses. This study found better clarity and acuity with RGP lenses, especially for near vision.
Area of Science:
- Ophthalmology
- Optometry
- Vision Science
Background:
- Presbyopia affects the eye's ability to focus on near objects, commonly requiring reading glasses or multifocal contact lenses.
- Bifocal contact lenses offer a potential solution for presbyopia by correcting distance and near vision simultaneously.
Purpose of the Study:
- To compare the visual performance of bifocal rigid gas-permeable (RGP) contact lenses versus bifocal soft contact lenses in individuals with presbyopia.
Main Methods:
- A crossover study design was employed with 16 healthy presbyopic subjects experienced in contact lens wear.
- Contrast visual acuity (distance and near) was measured under photopic and scotopic conditions for both lens types.
- Subjective clarity ratings and lens preference were collected after lens wear.
Main Results:
- Bifocal soft contact lenses showed decreased distance and near visual acuity at lower contrast levels under photopic conditions.
- Bifocal RGP lenses demonstrated a decrease in distance visual acuity at 5% contrast under scotopic conditions.
- Subjects reported significantly clearer near vision with bifocal RGP lenses compared to soft bifocal lenses.
Conclusions:
- Bifocal rigid gas-permeable contact lenses provide superior visual performance compared to bifocal soft contact lenses for presbyopic individuals.
- RGP bifocal lenses may be a preferred option for presbyopic patients seeking improved near vision clarity.
Related Concept Videos
01:16Focusing of Light in the Eye
Light rays enter the eye through the cornea, a transparent dome-shaped tissue that is the eye's outermost layer. The cornea bends or refracts, light rays traveling to the pupil. The shape of the cornea determines how much of the light is bent and whether the image will be focused correctly on the retina at the back of the eye. Once the light has passed through both refraction layers, it converges into a single focal point onto a small area. This is where photoreceptors start transforming...
01:20Anatomy of the Eyeball
The eye is a spherical, hollow structure composed of three tissue layers. The outer layer — the fibrous tunic, comprises the sclera — a white structure — and the cornea, which is transparent. The sclera encompasses some of the ocular surface, most of which is not visible. However, the 'white of the eye' is distinctively visible in humans compared to other species. The cornea, a clear covering at the front of the eye, enables light penetration. The eye's middle layer, the vascular tunic,...
01:15Depth Perception and Spatial Vision
Depth perception is the ability to perceive objects three-dimensionally. It relies on two types of cues: binocular and monocular. Binocular cues depend on the combination of images from both eyes and how the eyes work together. Since the eyes are in slightly different positions, each eye captures a slightly different image. This disparity between images, known as binocular disparity, helps the brain interpret depth. When the brain compares these images, it determines the distance to an object.
01:28Angle Closure Glaucoma: Treatment
Angle-closure glaucoma, or closed-angle glaucoma, is an eye condition where the iris bulges out and blocks the iridocorneal angle, resulting in a buildup of aqueous humor and increased intraocular pressure. Immediate medical attention is necessary due to the sudden onset of symptoms. The treatment for angle-closure glaucoma includes short-term and long-term approaches. Short-term treatment involves using eye drops like pilocarpine to lower intraocular pressure by increasing aqueous humor...