Hyperopia is the medical term for far-sightedness, a condition of the eye in which light focuses behind as opposed to on the retina, causing close objects to appear blurry while far objects may just be normal.
It is important to note that while this condition is chiefly characterized by blurry close objects, objects at all distances may eventually blurry should the condition go unattended.
There are two main causes of Hyperopia namely; low converging power of the eye lens as a result of the weak action of the ciliary muscles and an abnormal shape of the cornea.
Aside from the two major causes highlighted above, this condition may also be as a result of diabetes as well as problems with retinal blood vessels, though these cases are rare.
It has also been observed that the condition may be present at birth though due to the flexible nature of children eye lens, it is normally made for with ease.
There are three modes of classification of hyperopia and these include; the clinical appearance of the condition, the severity of the condition and the manner in which the condition relates to the accommodative status of the eye.
Based on the modes of classification above, there are three main categories of this condition as discussed below:
Classification by Clinical Appearance
- Simple Hyperopia – This type of hyperopia results from a decreased convergence power of the cornea or a decreased axial length.
- Pathological Hypropia – It results from atypical development, trauma or an eye disease such as cataract, nanophthalmia, microphthalmia, aniridia and many more.
- Functional Hyperopia – This form is due to paralysis of accommodation and is common at birth and may also be caused be certain drugs such as cycloplegics.
Classification by Degree of Refractive Error
- Low Hyperopia – Under this category, the error is +2.00D or less.
- Moderate Hyperopia – This is the category where the error ranges between +2.25 and +5.00D.
- High Hyperopia – This is considered the most severe form under this category and the error is usually +5.25 or more. It is usually linked to the blurring of the optic disk margin referred to as pseudopapilledema.
Classification by Role of Accomodation to Visual-Functioning
- Facultative Hyperopia – This form can be overcome through accommodation.
- Absolute Hyperopia – Cannot be overcome by accommodation.
- Total Hyperopia – This is the sum of the absolute and the facultative hyperopias.
The most common symptom of this condition is loss of visual acuity or squinting at close distances.
Patients will also report asthenopia which is a eye strain as a result of the condition. Because eye strain is also closely linked to such works as writing, reading or computer work, patients will also report headaches.
Some patients have also reported difficulty seeing with both eyes as well as difficulty with depth, though these cases are few and far between.
The condition can be diagnosed via the silt lamp test. In this test, certain parts of the eye such as the cornea, iris, and the conjunctiva are examined using a yellow dye.
There may also be other tests based on the severity of the condition such as Glaucoma test, Refraction testing, Eye movement, Retina testing and Visual acuity.
However, it is important to note that visual acuity is not a sure way of diagnosing the condition as there may be a wide range of other problems that may present themselves in a similar fashion. Such include but not limited to serious retinal elevation, orbital tumors, posterior scleritis, hypoglycemia, presbyopia and cataract.
The following are some of the treatment options for hyperopia
–LASIK, an acronym for laser eye surgery which is commonly used to reshape the cornea so that the patient would not require glasses.
PRK, which involves removal of a minimal amount of the corneal surface.
-LASEK which resembles PRK but makes use of alcohol to make the corneal surface loose.