Myopia
Overview
Also known as short-sightedness, myopia is a refractive disorder where light focuses in front of the retina instead of on it. This may be due to a longer eyeball shape or an overly strong lens.
Clinical significance
- Associations:
- Prematurity
- Marfan’s syndrome
- Ehlers-Danlos syndrome
- Complications:
- Primary open-angle glaucoma
- Retinal detachment
- Cataracts
Hypermetropia
Overview
Also known as hyperopia or long-sightedness, hypermetropia is a refractive disorder where light focuses behind the retina instead of on it. This may be due to a shorter eyeball shape or a lens that isn’t strong enough.
Clinical significance
- Mild hypermetropia is common in babies and resolves by around 3 years of age
- Hypermetropia is associated with an increased risk of acute angle-closure glaucoma
Astigmatism
Overview
To see an image clearly, light must focus at a single point on the retina. In astigmatism, the shape and curvature of the eye lead to rotational asymmetry resulting in a blurred image. In many cases, it can be thought of as the eye being “rugby ball-shaped”.
Clinical significance
- Most cases are sporadic
Presbyopia
Overview
Also known as age-related farsightedness, this describes a physiological insufficiency of accommodation associated with ageing. This occurs due to reduced elasticity of the lens and usually presents with farsightedness at around 40 years of age.
Clinical significance
- Many patients struggle to perform tasks in darker environments and struggle to read things near their faces. They may also experience eye fatigue and headaches when performing too much work requiring near-sightedness.
Anisometropia
Overview
- This describes when two eyes have unequal refractive power. This can lead to mild features such as mild short-sightedness in each eye, or more serious consequences such as amblyopia in children.
