As we enter adulthood, eye trauma, or the seemingly ‘early’ onset of age-associated eye conditions, can come as a cruel shock. Modern lenses offer a range of solutions, however.
Common eye problems affecting young adults
Aniridia is the absence of an iris, which is the coloured part of the eye.
Anisometropia is an imbalance in the prescription between one eye and the other.
Astigmatism is a condition whereby the cornea is more curved along one meridian and less along another, resulting in a cornea that is rugby ball-shaped. Consequently, the eye cannot resolve images into sharp focus, no matter what distance an object is viewed from or how much the viewer accommodates.
A caustic burn is a chemical burn to the eyes, usually the result of it coming into contact with an irritant, such as an acid or alkaline.
Corneal dystrophies are a group of conditions that are genetic in origin and cause the normal metabolism of the cornea to not operate normally. These may or may not cause symptoms (asymptomatic). Some are progressive in nature and may produce both visual issues and discomfort.
The cornea is the thin, transparent structure at the front of the eye. Any opacity or scarring of the cornea can prevent light from passing through it, or cause the light to scatter, causing glare.
The eye is lubricated by tears produced by the lacrimal gland as well as mucous and oily secretions produced by glands in the eye and the lids, but as we get older our eyes lids become less efficient. Dry eye syndrome is when this issue becomes a permanent problem rather than an occasional irritation.
In a long-sighted or hyperopic patient the eye is normally too short for the focussing power of the eye. Light rays enter the eye from a distant object and are focussed on a point behind the retina, resulting in an out-of-focus or blurred image.
Inability to wear spectacles
While many contact lens wearers choose to wear lenses rather than spectacles for cosmetic reasons, and some wear them for visual needs, there is a group of patients who cannot wear spectacles because they are allergic to frame materials, or have some facial injury or problem that means that conventional spectacles are not suitable.
Intolerance to moulded contact lenses
The diameter of most eyes falls within a limited range. By carefully selecting the correct base curve and diameter, a manufacturer can customise a lens design for any eye. If you are unlucky enough to fall outside of this stock size, then you may struggle to achieve the comfortable wear that most people experience.
Astigmatism is normally caused by the cornea being more curved in one direction than another. Fortunately, the maximum and minimum curves are normally at right angles to one another, resulting in a surface rather like that of a rugby football. Irregular astigmatism is normally the result of injury or keratoconus and occurs when the cornea is pulled into a distorted shape, due to scarring or the progression of a cone in keratoconus.
In keratoconus, the cornea, which is the clear dome-shaped structure at the front of the eye, bulges forward making the surface of the cornea irregular in shape and distorting vision through the affected part.
Commonly referred to as a corneal transplant, the term keratoplasty applies when all or part of a damaged or diseased cornea is removed and replaced with a donor cornea.
In a short-sighted or myopic eye the eye grows too long, and rays of light entering it from a distant object are focussed at a point in front of the retina, which means that the image appears blurred.
Myopia is not just an inconvenience to be corrected by glasses or contact lenses. Higher rates of myopia can give rise to more serious pathologies, such as retinal detachment, and the trend is towards higher and higher degrees of myopia.
Pellucid marginal degeneration (PMD)
Pellucid marginal degeneration, or PMD, is often confused with keratoconus, and indeed it is a type of irregularity affecting the cornea which results in visual impairment. PMD is caused by a thinning of a narrow band of the cornea between 4 and 8 o’clock, approximately 2mm in from the edge of the cornea and the white of the eye.
In trichiasis the eyelashes turn inwards and irritate the cornea and conjunctiva.