Glaucoma, Macula and Cataracts
Learn about the causes, symptoms, and treatment options for Glaucoma, Macula, and Cataracts in this comprehensive article. Find out how to protect your eye health and prevent vision loss from these common eye conditions.
Glaucoma
Currently 80 million people worldwide have Glaucoma and it is predicted that this number will grow to 111millionby 2040."Global Prevalence of Glaucoma and Projections of Glaucoma Burden through 2040", Ophthalmology 2014; 121:2081-2090Early stages of Glaucoma do not have any symptoms and is not related to things like general blur, eye discomfort or whether someone wears glasses or not. This group of eye disorders eventually lead to loss of the nerve fibres that run through the optic nerve sending signals to the brain. The Optic nerve is really an extension of the brain much like the spinal cord. Many people are unaware they have the condition until there is significant vision loss. Initially, glaucoma affects peripheral or side vision but it can advance to central vision loss and even blindness in some cases.
Risk factors include:
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Family history
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High myopia ( short sightedness)
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Thin cornea
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Age over 60
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Medical conditions e.g. Diabetes, High Blood Pressure, Heart disease
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Use of Corticosteroidseg Cortisone, Prednisone
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High eye pressure
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Suspicious optic nerve (large cupping)
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Eye injury or trauma
Interestingly, high eye pressure is not a diagnosis of glaucoma as people with high pressure may not develop glaucoma and conversely those with normal or low pressure may do so. What is important in diagnosing glaucoma is to understand the pressure level that is too high for a particular eye’s optic nerve. The exact cause of glaucoma is unknown and although eye pressure is a significant there are other theories about blood supply to the eye also being a factor.
Types of Glaucoma and their possible causes
Primary Open Angle Glaucoma – The Angle referred to here is the area that filters fluid in the eye ( formed by the iris and the cornea) This may become compromised allowing fluid to build up increasing internal eye pressure compressing the optic nerve. It is a painless slow vision loss of part of the field of vision not the central vision used to say read a book or see street signs.
Normal-tension glaucoma – The optic nerve here is damaged despite normal or low eye pressure readings. It is proposed that chronic vascular perfusion (blood supply) such as in nocturnal hypotension, over treated hypertension, Raynauds syndrome, migraine and atherosclerosis.
Secondary glaucoma – This type of glaucoma occurs as a result of other eye or medical conditions or trauma to the eye.
Angle-closure glaucoma – This type of glaucoma, also called closed-angle glaucoma or narrow-angle glaucoma, is a less common. Closure of the angle can be acute with sudden onset of pain and blurred vision and is a medical emergency. Chronic or gradual angle closure can happen with age as the eyeball becomes larger and the lens ages it becomes thicker taking up more space causing the angle to narrow and pressure build sup as drainage is compromised. The other eye is usually at risk as well in these cases.
DIAGNOSIS
Glaucoma is found via a comprehensive eye examination that will determine what is a progressive disease by the appearance of the optic nerve over time as well as loss of nerve fibre and possible vision loss. Tests may include :
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A thorough patient history to determine any risk factors particularly a family history of Glaucoma
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Visual acuity measurements to determine if vision is being affected.
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Tonometry to measure the pressure inside the eye.
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Pachymetry to measure cornel thickness (increased risk with thinner corneas)
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A Visual Field test to quantify the central and peripheral vision by a series of light targets to determine if there is a reduced sensitivity outside what is age normal . This is also used to show if any progression of the disease has occurred or into the disease state from a previously healthy eye.
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Examining the retina (inside movie screen of the eye) which may include photographs or scans of the optic nerve, to monitor any changes over time.
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Additional testing may include gonioscopy which looks at the angle of fluid drainage. Other devices can be used to look for specific loss of the nerve fibre function.
TREATMENT
If vision loss has occurred no treatment will restore this however the aim of treatment is to stop or reduce further vision loss.
Medications
The aim of these drugs in eyedrop form is to reduce the fluid pressure in the eye. One or a combination of these will be prescribed by an Eye Doctor. Ongoing monitoring of the optic nerve will determine if these are effective. This as well as minimising side effects may mean that eye drops are changed over the lifetime course of treatment.
Surgery
Surgical options for the treatment of glaucoma can be via traditional incision surgery such as trabeculectomy, deep sclerectomy and glaucoma drainage device surgery. These are very effective with a higher risk profile.
Modern procedures referred to as MIGS (minimally invasive glaucoma surgery) these surgeries can be somewhat less effective than traditional surgery but are safer. MIGS can be characterised into procedures that assist the eye’s natural internal drainage and those that create a small controlled flow to the external surface of the eye. Often this surgeries are generally undertaken in conjunction with cataract surgery.
Any decision regarding glaucoma surgery will be discussed at length with your eye Doctor to weigh up the risks and benefits.
Age-related Macular Degeneration (AMD)
The macula is a tiny delicate structure that is the centre “bullseye” of your Retina (the movie screen of your eye which gives you detail and colour vision), used for example to read and see people’s faces. It is not responsible for your peripheral vision.
There are many diseases of the macula of which degenerative age change is the most commonly known. Age is the biggest risk factor, however a controllable risk factor is smoking. Smokers are 2 - 4 times more likely to develop macular degeneration (AMD) than non-smokers.
The disruption of the cell structure and organisation interrupts communication and signalling resulting in a waste build-up seen as bright yellow deposits called drusen via Digital Fundus Photography.
There can be no symptoms in early AMD, however as the condition progresses fine detail can be difficult to see as well as vision distortion or parts of objects may appear to be missing.
THE CLASSIFICATIONS OF AMD
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Dry – due to loss of cells in the macula. Develops slowly and irreversibly reduces vision. Currently there are no approved treatments for this late-stage AMD
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Wet – due to abnormal blood vessels growing under the macula and leaking. Sudden vision loss is noticed quickly, unlike slow Dry AMD.
TREATMENT
Treatment for wet AMD is via medication injection into the eye. The progression of macular degeneration and individual responses to treatment are highly variable. Ongoing injections are often necessary to help stabilise vision. This does not cure the disease.
In some people vision is improved.
Self-monitoring between eye check-ups can be done with an Amsler Grid at home. This is a check pattern around a black fixation point. Your Optometrist can discuss lifestyle changes and diet to maximise macular health.
Cataract
Cataract in most cases is an ageing process of the human lens located behind the pupil, the opening of light entering the eye. As the lens hazes and is no longer a clear pathway for light to the back of your eye – its “movie screen”.
There are other risk factors, which include:
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Smoking
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Diabetes
Prolonged use of oral steroidal medications.
Symptoms you may experience include difficulty reading, seeing well at night and glare when driving at night or sensitivity to sunlight.
There are different cataract types by location:
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Nuclear sclerotic – the most common type is a general hardening and yellowing of the lens that can take many years to develop, usually slowly. This can in the hardening phase give you temporarily good near sight for some months or years. Some people even discard their reading glasses. However, eventually this progresses to worsen vision.
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Cortical Cataracts – these changes start at the edge of the lens structure and appear like spokes of a bicycle wheel. They affect vision eventually as the spokes (which are areas blocking light getting into the eye) extend to come into the visual axis, the centre of the vision.
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Posterior Subcapsular Cataract – as the name implies this opacification of the lens is at the centre back of the lens. It affects vision early on and develops quite quickly and in a younger age group. The world projected onto your eye’s “movie screen” is hazy. Poor night vision is a commonly experienced.
Cataract can be determined in a Routine Eye Check-up. You may need to alter your prescription to support your vision to be optimal whilst your symptoms are mild. Your Optometrist can help track the progress of cataract and work with you in determining when you are ready for surgical treatment. As we have worked with you we can provide the bridge between you and your eye surgeon about your desired vision outcomes after surgery, such as the need for good distance vision for golf or the need for sharp near vision for sewing or hobbies.
Surgery for cataracts is a two step process that involves removing your cloudy lens and replacing it with a clear, plastic intraocular lens (IOL). Cataract surgery is a safe outpatient microsurgery. The surgery only takes a few moments and for most, no stitches are required. After the surgery, patients return home and resume normal activities in a couple of days. The result of the surgery is a lens clear of cloudiness and an improvement in your vision.
The need for some use of eyeglasses after surgery is common. Your Ophthalmologist (surgeon) will review your healing some 3 to 4 weeks after surgery. Your course of eye drop therapy will be finalised and at this stage you can have your eyes re-tested by your Optometrist.
It is important to continue your regular eye examinations after cataract surgery to continue to monitor your eye health as you age. Having had cataract surgery does not exclude you from other eye diseases.