MACULAR DEGENERATION TESTS MACULAR EVALUATION

MACULAR DEGENERATION TESTS MACULAR EVALUATION

Age related macular degeneration is the leading cause of progressive loss of central vision even if asymptomatic with a huge impact on ones quality of life.

Be Proactive. Reduce your risk factor or slow  down the  progression of all forms of AMD as part of your regular eye examination and for the health benefits it can bring. People suffering from age-related macular degeneration  have twice the risk of dying from heart disease and stroke.

 

lady for macula check
macular disease foundation

Peter D’Arcy investigates eye disease by a range of procedures including  the latest canon ocular coherence tomography

macular degenration

Age-related macular degeneration (AMD) is a disease associated with an aging immune system that blurs or distorts the critically important and most accurate central vision. This area  is susceptible to oxidative stress because it consumes high levels of oxygen which then leads to the production of high levels of free radicals which can be reduced by anti oxidants

The dry form refers to dry macular degeneration as does the wet form to wet macular degeneration.

DRY AMD (atrophic)(often treated with nutrition,weight control) central deterioration in early stages before blood vessels grow.
WET  AMD (neovascular or exudative). Treated by embryonic stem cells  that can be surgically implanted into the retina,laser therapy or intravitreal injections  employed to lower spread which can occur as abnormal blood vessels grow,some being leaky blood vessels.

(OCT) scans to determine if you have the earliest or advanced signs of macular degeneration

The OCT scans often employed in eye disease studies test for any distorted vision by high resolution of retinal anatomy for abnormal blood vessels in the early stages of loss of central vision to legal blindness. It helps differentiate the two main types of  AMD.

 

Macular degeneration types

looking inside the eye

OCT Angiography (OCTA) is a technology that reproduces retinal blood vessels by the reconstruction of retinal tomograms. With this technology one can observe the retinal vascular state without fluorescein angiography, which is invasive and may cause strong allergic reaction.

To generate the image of the retinal microvascularisation, each B-scan of the examination pattern is consecutively
repeated several times. The contrast comparisons on consecutive B-scans at the same location show areas with a change in contrast  over time and some areas where it remains constant. This is linked to the movement of  red blood cells and hence the location of the vessels.

Cover one eye at a time to look for any distortion evident on a Amsler Grid

Diabetic retinopathy and  the neovascular  type of age-related macular degeneration are the two most frequent retinal degenerative diseases causing  the majority of blindness found in an eye exam.
Exudative retinal detachment can be caused by age-related macular degeneration, injury to the eye, tumors or inflammatory disorders

Stargardt’s disease is the most common form of juvenile macular degeneration.The second most common form of juvenile macular degeneration is Vitelliform macular dystrophy, also referred to as Best disease when it begins before age 6.

Amsler grid, Macular Scan,OCTA

octa exam
octa scan
retinal layers
  • Capillaries can be observed without using fluorecein
  •   Blood vessels can be observed in a designated layer
  •   Microaneurysm and non-perfusion areas can be identified.
  •   CNV(Choroidal neovascularization)  can be identified.
  •   Blood vessels at the back of any leakage can be observed
  • ​ Frequent inspection is possible due to less burden on patient with shorter inspection time
  •  Blood flow visualization is possible in any depth from retina to choroid however the actual leakage cannot be detected (requires fluorescein angiography)

The vitreous is a transparent gel composed of water, collagen, and hyaluronic acid it occupies 80% of the volume of the eye,sometimes it can liquefy somewhat and cause floaters. Epiretinal membranes (ERMs) are sheet-like structures that develop on the inner surface of the neurosensory retina. 

The macular changes that result from either ERM or VMT (vitro-macular traction) lead to similar symptoms: reduced visual acuity, metamorphopsia, difficulty using both eyes together, and even diplopia Epiretinal membranes may evolve between the neurosensory retina and a vitreous attachment. Vitrectomy does carry some risks (e.g., cataract, retinal tears, retinal detachment, endophthalmitis) 

The OCT scans monitor for any distorted vision  by high resolution of retinal anatomy and can even be used as a sensitive early marker of dementia.  OCT scanning may mirror changes going on in the blood vessels in the brain.
Optical coherence tomography (OCT) is a high-resolution, three-dimensional, noninvasive imaging technique. It is often called an optical ultrasound as it is similar to ultrasound imaging but  it obtains subsurface information from laser Interferometry.
People with thinner retinas are more likely to have problems with memory and reasoning according to the dementia study JAMA
OCT scans  have a role in risk profiling also for systemic stroke, myocardial infarction, hypertension, diabetes and an array  of eye health disorders.

If you’re over 50 you are at higher risk of AMD  and everyone with diabetes is at risk of vision loss through diabetic eye disease.

OCT layers
LAYERS OF POSTERIOR RETINA AND CHOROID 
1    retinal nerve fiber layer
2ganglion cell layer
3inner plexiform layer
4inner nuclear layer
5outer plexiform layer
6outer nuclear layer
7external limiting membrane
8photoreceptor inner segment -outersegment junction
9cone outer segment tip
10retinal pigment epithelium
11choroid
12                                                             SCLERA 
retinal layers
VITREOUS FLOATERS

 

vitreous floaters
macular scan

Your eyes have abberations overcome by its  movements and have high resolution in a very small part of the eye responsible for the centre of your vision called the macula.

You have a blind spot where your optic nerve takes the focused vision to the brain.

To take in more information,you move your eyes around a scene to correct for these imperfections in your visual system. 

The OCT scan is particularly useful for high resolution anatomical pathology detection. Having 3micrometre resolution (a red blood cell is about 8 micrometeres)  OCT imaging data extracted by blood flow information and then from reconstructing blood vessel images due to changes in brightness  blood flow can be determined in the greatest of detail.

Eating for your eyes and healthy habits.

The eyes require antioxidant activity to flush out toxins of oxidative stress produced as a result of metabolic reactions.

Indeed certain patients can benefit from a specific mix of vitamins and minerals to slow the diseased condition. Every cell membrane has omega-3 fatty acids which has an anti-inflammatory effect compared with the Omega-6 type  It is desirable to eat more  Omega-3’s in our diet (oily fish, leafy greens etc.)  Omega 6 plant oils needs to be reduced eg margarine, corn, sunflower, soybean in processed foods such as chips. 

Attention to diet eg particular fruit and vegetables eg being a good source of beta carotene (needed to create vitamin A )and antioxidants that also helps with the immune system as well as an array of medical approaches are required to limit potential vision loss.   

How many of these “healthy habits” can you tick off?
No smoking  and a healthy, well-balanced source of antioxidants.  

  • Nuts, fresh fruit and vegetables 
  • Fish two to three times a week
  • Low glycemic index (low GI) carbohydrates instead of  high GI
  • Limiting intake of fats and oils
  • Maintaining a healthy weight,exercise regime and lifestyle.
  • Ensuring regular comprehensive eye tests including macula checks 
  • The Omega 3 to Omega 6 ratio can be present in western diets  1:20 versus the healthier 1:4 in Mediterranean diets.
  • National Eye Institute USA Age-Related Eye Disease Study (AREDS) 2001  clinical trial showed high levels of antioxidants and zinc can reduce some people’s risk of developing advanced AMD by about 25 percent
  • Smoking harms lungs and your eyes. Smokers are four times more likely to develop macular degeneration than non-smokers.
eating for eyes

The correct intake of plant based foods, carrots,eggs,milk and yogurt ,whole grains, quinoa, whole lentils, oats, brown rice ,oysters,red bell pepper,sunflower seeds, lentils, kidney beans, chickpeas, green peas, sprouts sweet potatoes among others are all vital for eye health as they supply the antioxidant activity  including the essential vitamins A,C,E omega-3,Zinc, Zeaxanthin,beta-carotene,lycopene,lutein,selenium.

Sources of  antioxidants can be found in vitamins A, C and E, Dark chocolate, the minerals selenium, zinc and copper, and can also be found in phytochemicals from plants, fruits and vegetables.  Too high doses of antioxidant supplements may work against your own antioxidants which are produced naturally rather than artificially.

Treatment options

​Macutec once daily is an AREDS  2 formulation designed to reduce AMD implications from side effects of oxidative stress
AREDS-2 was an important five-year clinical study that demonstrated positive results for dietary lutein and zeaxanthin being a safe and effective alternative to beta-carotene. 

eye drops and tablets
  • Vitamin E  400 mg
  • Lutein 10 mg   Zeaxanthin 2 mg
  • Zinc (from Zinc Oxide) 25 mg    Copper (as Cupric Oxide) 2 mg
  • Ascorbic acid (Vitamin C) 500 mg​
  • Omega-3 fatty acids – Eicosapentaenoic acid (EPA), and Docosahexaenoic acid (DHA). 
  • The DHA in fish oil is essential for normal retinal  functioning. 

Macutec Once Daily doesn’t contain beta-carotene with its ill effects or fish oil unlike other alternatives eg Lacritec.  Fish oil has a slight blood thinning effect so it is advised to consult your GP if you are taking blood thinning drugs such as warfarin.
Fish oil is an especially rich source of omega-3 fatty acids, which are also found in flaxseed, walnuts, and dark leafy greens. 
There are no known significant drug interactions with Macutec Once Daily
The human body is capable of producing all the fatty acids it needs, except for two: linoleic acid (LA), an omega-6 fatty acid, and alpha-linolenic acid (ALA), an omega-3 fatty acid both found in plant and seed oils.
Omega-3s have anti-inflammatory benefits and help prevent heart disease, whereas Omega-6s lower blood cholesterol and support the skin.
Modern food processing and storage can rob many foods of much of their nutrition. For some natural sources it is difficult to actually eat the quantities required. Examples include fish and spinach. Even food preparation can reduce the nutrition content.
 Macutec is based on a very large clinical trial which showed a significant benefit in slowing the progression of macular degeneration. The majority of the people who were on this trial and showed benefit were also eating healthily. 
Sometimes Resveratrol in red wine is thought to help reduce abnormal angiogenesis.

Blue light protection

Crizal Prevencia lenses are the result of several years of research at  the Vision Institute in Paris, France . By filtering  light wavelengths toxic to retinal cells the risk is lessened.
 
blue light prevencia

Most AMD starts as the dry type and in 10-20% of individuals, it progresses to the wet type.

You can have the early signs without knowing so intervention can be sought.

The Age-Related Eye Disease Study 2 (AREDS 2) was a multi-centre,randomised trial designed to determine the correct composition for macular supplements.

Macutec Essentials are the preferred option for people that need a smaller capsule option taken twice daily,otherwise Macutec Once Daily is recommended.

Macular supplements contain just the right amounts of C and E vitamins along with zinc, lutein and zeazanthin to support your macular health.

Those with susceptible family history for ARM can consider predictive genetic testing, quit smoking, lower cholesterol, and be conscious of your environmental light exposure, and perhaps consider supplementation with antioxidants, such as lutein and zeaxanthin.

The blue violet light  between 415 to 455 nanometres on the light spectrum is believed most toxic to retinal cells and for long-term vision issues such as age related macular degeneration^

Blue light wavelengths  boost our concentration so can impact on sleep 
Blue light  can damage the retina so at risk groups  – family history of AMD, smokers, people who are obese,children can benefit by blue light filter especially when outside.
AMD patients need to wear tinted glasses because of photostress. There can be  many situations where the absorption is too dark or unsuitable ,requiring need for different filter values,sometimes more cheaply overcome by fitover shields of which we have in different densities.

 

^Transmission of light to the aging human retina: possible implications for age related macular degeneration
Experimental Eye Research, 79(6), 753-759, 2004

Photodynamic therapy (PDT) and the administration of compounds acting against vascular endothelial growth factor (anti-VEGF) are approved for the treatment of choroidal neovascularization (CNV) secondary to AMD. 

Periodic intravitreal (into the eye) injections are sometimes required.  Cell-penetrating peptide eye drops will drive the next generation of treatment for people with AMD rather than intraocular injections. Drugs that can activate proteins found in blood vessel cells are being developed to make the blood vessel more stable. Abnormal blood vessel growth and leakage are two primary factors in both age-related macular degeneration and diabetic retinopathy.

In the wet rather than the dry form of ARM anti vegf drugs some now plant based are normally administered by intravitreal injection rather than topical eye drops to reach the back part of the eye.

Photodynamic therapy uses laser light and light-sensitive dye to seal off the leaking areas. Free radicals, referred to as oxidants are unstable molecules in the body with unpaired electrons.

Oxidative stress plays a pivotal role in developing and accelerating retinal diseases including the leading cause of  blindness in Austrlia -age related macular degeneration (AMD) the part of the eye responsible for central vision, glaucoma, diabetic retinopathy (DR), and retinal vein occlusion (RVO). 

Risk factors for retinal vein occlusion  which can cause other problems like heart attacks and strokes. The main risk factors are:

  • Age (most retinal vein occlusions happen in people over 60)
  • High blood pressure
  • High blood lipid levels
  • Diabetes
  • Smoking
  • Overweight

If a retinal vein occlusion causes fragile, abnormal new blood vessels to grow in the eye the risk of beeding can be minimised  by using laser and/or intra-ocular drug injections.
If the central macula is affected and vision is reduced due to swelling of the central macula, treatment with anti-VEGF drugs may be used. Anti-VEGF drugs are administered as injections into the eye. The usual treatment regimen begins with monthly injections for three months. Then to maintain control of the disease, injections are typically continued on an indefinite basis, or until the swelling has resolved.

We also use digital retinal photography and employ tests to measure the effect on vision and if any distortion is present often involving an eye drop to dilate the pupil. 

We can enhance vision by glasses and electronic magnification and with timely referral for laser intervention,injections or surgery. 

Macular Telangiectasia (“MacTel”)

(as distinct from macular degeneration)

 Type 1: congenital and unilateral
Type 2: acquired and bilateral. The most common form of the three types.
Type 3: Primarily occlusive phenomena which is quite rare.
With MacTel, the blood vessels around the fovea become dilated and leakage can be a sign of and cause of  damage.

Type 1 MacTel involves localised dilations, or aneurysms and sometimes bleeding of blood vessels but without the “new” blood vessel growth characterised by widespread dilation and leakage

The MacTel project
The MacTel Project is a collaboration involving more than 60 centres from around the world to better understand the progression of their disease

 

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