Amblyopia (Lazy eyes)

Amblyopia is a neuro-developmental condition in which vision does not develop adequately in one eye. Amblyopia may be caused by any condition that affects normal visual development or use of the eyes including an eye turn, uncorrected refractive error, or ocular pathology which blocks light from reaching the retina such as a cataract. In each of these cases, the brain chooses to ignore the image produced by the affected eye (known as suppression), which inhibits the growth and development of the nerve fibers of the affected eye. Most children adapt well to seeing through one eye, so many parents are unaware that the child has a problem and the condition often goes undiagnosed. All children are recommended to have a thorough eye examination before they start school.

Astigmatism

Astigmatism is a condition in which the shape of the cornea – the clear window at the front of the eye – is unequal in different directions. A useful analogy is to compare the shape of a soccer ball with a rugby or AFL ball. A soccer ball is spherical in shape with equal curvatures in all meridians. The surface of a rugby or AFL ball on the other hand, has different curvatures in the horizontal and vertical meridians i.e. the horizontal meridian is flatter, whilst the vertical meridian is steeper. The shape of a normal cornea typically resembles the shape of a soccer ball whereas an astigmatic cornea can be likened to the shape of a rugby or AFL ball. Symptoms of astigmatism include headaches, fatigue, eyestrain, as well as distorted or blurred vision.

Blepharitis

Blepharitis is a common condition that causes inflammation of the eyelids. Blepharitis is often associated with overgrowth of bacteria or a parasite known as demodex on the eyelashes or eyelid margins. Blepharitis can affect people of all ages and is often associated with certain skin conditions including acne, rosacea and seborrheic dermatitis. Common signs and symptoms of blepharitis include chronic irritation, redness of the eyelid margins and crusting of the eyelashes (particularly in the morning).

Cataract

Cataract is a condition which causes clouding of the clear lens in the eye and is one of the leading causes of vision impairment. Cataracts can be congenital yet more commonly occur with age as the focusing lens in the eye becomes progressively less clear, disrupting the flow of light through the eye and onto the retina. Cataracts are generally slowly progressive but certain types of cataracts can progress more quickly. Common symptoms of cataract include blurred vision, sensitivity to glare and distorted or double vision.

Colour vision deficiencies (CVD)

Colour vision deficiencies (CVD) (sometimes called colour blindness) represent a group of conditions that affect the perception of colour. Red-green colour vision defects are the most common form of colour vision deficiency.

CVDs are almost always inherited in an X-linked recessive pattern, although they can be acquired as a result of particular diseases and injuries. Males are affected by X-linked recessive disorders much more frequently than females since males have only one X chromosome and females have two, both X chromosomes on a female would have to have a genetic change in order to cause the disorder.

Males inherit their X chromosome from their mother and their Y chromosome from their father. Therefore, if a mother is a carrier of a CVD on one of her two X chromosomes, her son has a 50/50 chance of inheriting a CVD. Since females have two X chromosomes, one from the mother and one from the father they have less of a chance of being affected. About 8% (1 in 12) of males and 0.5% (1 in 200) of females have CVDs.

CVDs affect the ability to discriminate between certain colours such as red and green. A person with a CVD will try to discriminate colour differences by using other cues such as brightness differences. CVDs often do not impair quality of life but can affect career choices where colour discrimination is important for safety reasons.

Diabetic retinopathy

Diabetic retinopathy is a complication of diabetes where the tiny blood vessels in the retina at the back of the eye become damaged and begin to leak blood and other fluids, which can lead to vision loss.

Most people, who have suffered from diabetes for over 20 years, will have some degree of retinopathy (nearly all patients with Type 1 diabetes and 58% of patients with Type 2 diabetes).

Early signs of diabetic retinopathy include small haemorrhages and microaneurysms appearing in the retina. In later stages, excessive microvascular leakage can cause swelling at the macular (the region of the retina responsible for all detailed central vision).

Symptoms of diabetic retinopathy include blur or loss of vision. For diabetics, strict control of blood sugar levels is essential in preventing the progression of diabetic retinopathy.

At Charlestown Eyecare we utilise Digital Retinal Imaging (DRI) and Optical Coherence Tomography (OCT) to detect diabetic retinopathy. Digital retinal imaging photographs the surface of the retina looking for signs of haemorrhages, lipid exudates or micro-aneurysms. OCT is a non-invasive imaging test, which uses light waves to take cross-sectional images of the retina. OCT allows the optometrist to see each of the retina’s distinctive layers allowing them to detect leaking blood or fluid beneath the surface of the retina.

i Hietala K, Harjutsalo V, Forsblom C, Summanen P, Groop PH; FinnDiane Study Group. Age at onset and the risk of proliferative retinopathy in type 1 diabetes. Diabetes Care. 2010;33(6):1315–1319. doi:10.2337/dc09-2278