Myopia
Nearsightedness (myopia- minus prescription), an eye condition most commonly diagnosed in childhood, can cause your distance vision to become blurry. Myopia can progress and worsen over time, leading to more severe sight conditions later in life such as retinal detachment, myopic maculopathy, glaucoma, and cataracts.
Myopia Management
Various methods that eye doctors use to slow down the progression of myopia in children to keep it from getting worse quickly.
Hyperopia
Farsightedness (hyperopia- plus prescription) is a common vision condition in which you can see distant objects clearly, but objects nearby may be blurry. The degree of your farsightedness influences your focusing ability. People with severe farsightedness may be able to clearly see only objects a great distance away, while those with mild farsightedness may be able to clearly see objects that are closer as well.
Astigmatism
Astigmatism (uh-STIG-muh-tiz-um) is a common and treatable imperfection in the curvature of the eye that causes blurred distance and near vision. Astigmatism occurs when either the front surface of the eye (cornea) or the lens inside the eye has mismatched curves. Instead of having one curve like a round ball, the surface is egg-shaped. This causes blurred vision at all distances. Astigmatism may occur in combination with nearsightedness or farsightedness.
Presbyopia
Gradual decline in the ability to focus on close objects or to see small print. Regardless of your prior vision correction needs, presbyopia is considered a normal and almost inevitable part of the aging process.
Amblyopia
The standard test for amblyopia is to have a patient read the eye chart. When one of the eyes can’t read the chart clearly (this is called poor visual acuity) even with corrective lenses, the patient has amblyopia. Because lenses cannot fix the vision in the weak eye, we know that there is a problem with the eye-brain connection: the eye is not communicating images to the brain properly.
Binocular Vision
Vision as a result of both eyes working as a team; when both eyes work together smoothly, accurately, equally and simultaneously.
Binocular vision dysfunction
General binocular dysfunction is the inability to move your eyes together in an effective manner. Each eye has six eye muscles that move the eyes in a coordinated manner. This movement is controlled by the brain. Signs and symptoms of general binocular vision dysfunction.
Strabismus
General binocular dysfunction is the inability to move your eyes together in an effective manner. Each eye has six eye muscles that move the eyes in a coordinated manner. This movement is controlled by the brain. Signs and symptoms of general binocular vision dysfunction.
Conjunctivitis
An inflammation of the conjuctiva, the thin, transparent layer that lines the inner eyelid and covers the white part of the eye
Floaters
Tiny spots or specks that float across the field of vision. Generally harmless, they can be a warning of certain eye problems, especially if there is a sudden change.
Cataracts
Opacity or cloudiness that usually develops gradually as the lens in the eye loses transparency and the lens material yellows. Cataracts are the leading cause of visual disability in people older than 65.
Dry Eye
Occurs when tear glands produce too few tears, causing itching, burning or even reduced vision.
Glaucoma
A condition in which the pressure in the eye increases, causing eye damage and potential blindness. A leading cause of blindness in the United States, glaucoma can be prevented if the disease is detected and treated in time.
Macular Degeneration
The progressive deterioration of the part of the retina responsible for central vision and a leading cause of blindness in America.
Retinal Detachment
The separation of the light-sensitive membrane in the back of the eye (the retina) from its supporting layers.
Sclera
The tough, white outer layer of the eyeball; with the cornea, it protects the entire eyeball.
Accommodation (also known as focusing)
The eye’s ability to adjust focus on objects at varying distances. See Near point of accommodation and accommodative facility. Behavioural theory suggests that focusing is closely related to the identification mechanism which ensures that the object under scrutiny is the most clearly seen ensuring it remains the centre of attention. See near point of accommodation and accommodative facility.
Convergence
The ability of both eyes to turn inwards together. This enables both eyes to be looking at the exact same point in space. This skill is essential to being able to pay adequate attention at near to be able to read. Not only is convergence essential to maintaining attention and single vision, it is vital to be able to maintain convergence comfortably for long periods of time. For good binocular skills it is also to be able to look further away. This is called divergence. Sustained ability to make rapid convergence and divergence movements are vital skills for learning.
Binocular
Of or involving both eyes at once.
Peripheral Vision
The ability to see or be aware of the vision around about us or to the sides. Defects in this ability can be caused by diseases such as glaucoma, tumors, retinal detachments and strokes to name but a few. Good peripheral vision is essential in driving, most sports and reading. Peripheral vision can be tested using visual field testing instruments.
Depth Perception
The ability to see in 3D or depth to allow us to judge the relative distances of objects. Often referred to as stereo vision or stereopsis.
Ophthalmologist
A doctor of medicine specializing in diseases of the eye and surgery.
Refraction
The part of an eye examination that determines the refractive error.
Refractive error
The measure of the error of focus of an eye compared to an assumed normal point of zero. The error is measured in diopters which is the reciprocal of the focal length in centimeters. The refractive error will include measurements for myopia (short sight), hypermetropia (long sight) astigmatism and presbyopia (the loss of focusing power due to age for near work).
Vision Therapy (also known as vision training)
Therapy involving exercises which are aimed at improving visual skills such as, eye teaming, binocular co-ordination and depth perception, focusing, acuity (clarity of sight), and “hand-eye” or “vision-body” co-ordination. Vision therapy can involve a variety of procedures to correct neuro-physiological or neuro-sensory visual dysfunctions. Practiced by optometrists.
Visual Acuity
The ability to see clearly at a distance. In Europe and the UK this is usually measured at 6 meters. It is usually given as a fraction where the top number is the distance at which the test is performed. The second figure is the level of vision. It is usual to think of 6/6 as normal. In the USA it is known as 20/20 because the distances are measured in feet instead of meters. The larger the number on the bottom of the fraction the worse the vision. Many people are able to see better than 6/6 and figures of 6/5 or even 6/4 are not uncommon.