Simple eye conditions

Dry Eyes :: Short Sight :: Long Sight :: Astigmatism :: Reading Difficulties

The eye is a precise image capturing device that relies on an image being formed on the retina by the focussing of light rays through the cornea and fine tuned by the internal lens. Given that the tolerances for good vision are extremely small and that these rely on the correct focussing power given the axial length of the eye all of which one would expect to be as variable as the size of any other part of our body it is a small miracle that many of us need no correction until in later life. When such a perfect fit is not present we end up with a need for optical correction.

Here are some common examples of blurred vision created by slight imperfections of our most valuable sense organ:

Dry Eyes

Short Sight

Long Sight

Astigmatism

Reading Difficulties

The causes, symptoms and treatment of dry eyes

see also our full page on dry eye conditions

You would be surprised how many people suffer from dry eye conditions often without realising the cause.There are estimated to be millions of sufferers worldwide and the problem has been exacerbated by modern environmental conditions caused by air conditioning, computer use and pollution. Even those with relatively normal tear production can suffer if their tear make up is unbalanced or their blink rate abnormal.

It is most common in women, and effects 11% of people between the ages of 30 and 60 and 14% of those older than 60 years old. Moreover it is recognised that more than 50% of contact lens wearers suffer from dry eye symptoms.

Let's take a look at what makes for dry eyes

The tears are for many reasons, to feed the cornea with nutrients, to ensure a smooth optical surface, and to lubricate the surfaces of the lids and cornea that come into contact in each blink and during sleep. They help flush away foreign debris and contain anti-bacterial substances which attack foreign bacteria before it reaches the eye’s surface.So if this important protection to the eye isn’t up to scratch ('scuse the pun) what are the symptoms like?

People complain of dry, itchy or tired eyes, which feel sore, gritty and irritating and are often red. This burning sensation produces photophobia (disliking of strong light) and sometimes blurry vision.

How can we manage Dry Eyes?

There are a number or treatments depending on the cause and severity of the condition. Among them are Tear supplements, Artificial tears, Ointments, sprays and better Lid hygiene as well as more invasive actions such as Punctal plugs to allow for better drainage into the tear ducts and Oral antioxidants as well as Nutrition.

Given a good response by far the simplest action is to use drops that will rewet the surface of the eye. It has been shown that these not only produce a healing effect but that prolonged regular insertion actually improves the condition, by improving the natural epithelium (the outer surface of the cornea) and creating important goblet cells.

Further Product Information

Clinitas Eye Drops - free samples available

Unable to see clearly distant objects and yet close objects are well focussed.

Cause

Either too much focussing power by cornea or too long an axial length of the eye (or combination of both) resulting in the image being focussed in front of the retina.

Correction

The placement of a negative concave lens (spectacle or contact lens) in front of the eye to diverge the light rays before being focused onto the retina.

Onset & Progression

Because we are normally long sighted at birth the development of the eye is to become less long sighted or more short-sighted. Those who are at birth less long sighted will therefore become short sighted throughout their early development. Some will show a gradual increase but others especially from the Orient will show rapid increases. Studies have shown that the early correction of myopia will reduce the eventual increase.

Visual symptoms

In the young to teenage years very little evidence of symptoms are noted. Some will complain of tired or itchy eyes particularly when concentrated viewing at distance and more so for close work is undertaken. At this age we can cheat by using wrongly our fine tuning internal lens to add power to our weak focussing system As we age our fine adjustment lens becomes less flexible and cheating becomes less possible until we are no longer able to do so. Hence close work problems arrive earlier for the hyperope and eventually both distance and near becomes blurred.

Cause

Either too little focussing power by cornea or too short an axial length of the eye (or combination of both) resulting in the image being focussed in behind the retina.

Correction

The placement of a positive convex lens (spectacle or contact lens) in front of the eye to converge the light rays before being focused onto the retina.

Onset & Progression

For the reasons expressed above many of us cope with small amounts of hyperopia until later in life. Significant power changes are rarely seen unlike myopia; however those who are highly hyperopic in early life often develop ocular motor disorders like convergent squints and lazy eyes. Because no visual discomfort is noticed much hyperopia goes undiscovered until the first aye examination which demonstrates the need for a check up before school age.

Visual symptoms

Indistinct but not blurred vision with a propensity to headaches, tired and watery eyes and a possible likleyhood of migraines.

Cause

Created by a non spherical shape of the cornea creating a different focus power through vertical or horizontal slices of it, or obliquely but always at 90 degrees to each other. Simplest way is to think of a non spherical shape like a rugby ball. If it were transparent it would focus light differently through its different curvatures. This can result in grater degrees of long sight or short sight for each axis or mixed astigmatism where one axis will be long sighted and the other short sighted.

Correction

The placement of an astigmatic lens exactly to coincide within a few degrees of the corneal deformity. Often when first prescribed this will require the brain to understand that continual focussing between each plane is not required and so for the first few days will create a tilting or nauseas effect which will soon disappear.

Visual symptoms

At the age of 40 plus things that used to be easy to see are becoming blurred, your watch, small print, and threading needles. Presbyopia is Greek for old eyes which is a little harsh in our increased longevity. Focussing close up becomes far more difficult thus moving the paper away from your body helps in the early stages. If your are long sighted you will begin to see symptoms earlier which might also include distance problems as well. Short sighted people notice the onset later and often amuse their friends when they remove their spectacles to read.

Cause

This is a result of your fine tuning lens loosing its flexibility through age changes disallowing it to bulge and flex to focus the close image on the retina.

Correction

An addition known as the reading addition is added either to your distance specs or given as reading specs. Old methods of correction added a segment or bifocal to the distance pair for dual vision, but these have been superseded by the much more efficient progressive, varifocal or no line bifocal. There advantage being that they give the user multiple focus points across a wide range of close work distances.

Onset & Progression

Starts around middle age and progresses till full addition correction is required at around 65.