Before cataract surgery: decide on outcome

If you have a cataract in one or both eyes and before cataract surgery, you will want to give some thought to the following:

  1. Do you want  a good chance to stop glasses wear after the cataract surgery in both eyes?
  2. If you do not mind wearing glasses after surgery, do you prefer to wear it for distance viewing or for near viewing?

These decisions will have bearing on the lens implant that your eye surgeon implants into your eye at the end of cataract surgery.

The current state of your cataracts in both eyes and your current glasses prescription may influence the choices available to you.  You should tell your eye surgeon your wishes so he/she can advise you.

Choices before cataract surgery

In general, the choices of outcomes when cataract surgery has been done in both eyes are:

  • Glasses needed for near viewing but not for distance.
  • Glasses needed for distance viewing but not for near.
  • No glasses needed – Multifocal lenses implanted into both eyes at the time of surgery.
  • No glasses needed for casual viewing but glasses may be needed for prolonged viewing – Monofocal lenses have been implanted to achieve monovision.

 

The final choice of outcome is sometimes down to your personal preference. Moreover, you should  take care when choosing monovision and multifocal lenses. Your eye surgeon can discuss the pros and cons of each choice.

Monovision is not for everyone. You should ask for a monovision trial before surgery to see if you are happy with monovison.

Multifocal lenses may cause you to see glare and haloes around lights.  Some people may find this disturbing. The lenses may also worsen your night vision in extremely dark environments.

In general “Glasses needed for near viewing but not for distance”,  is the most common choice, particularly among people who are already wearing glasses and do not mind continuing to wear them.

 

Wishing you a safe and successful surgery.

 

 

Floaters and Flashes: when to be concerned

Floaters and flashes are common eye complaints.

Floaters are little dots, specks, lines, clouds or shadows that people see in their vision.

They appear to be objects in front of the eye but are actually within the eye. They are more obviously seen against a white background or blue sky and in bright lighting. Most people have some floaters but only notice them when the number of them increase.

Flashes are dim lights, like lightning,  which are seen in the corners of the vision. they are more obvious in the dark and when moving the eye.

Causes of floaters and flashes

Most floaters are usually related to ageing. Due to ageing,  the jelly in the eye, the vitreous, changes.  The jelly in the eye becomes more liquid and interfaces form between the liquid and jelly causing shadows to be cast to the back of the eye. Due to these same changes, the jelly may also shrink and pull on the retina of the eye causing flashes to be seen. The retina is the nerve tissue of the eye that senses light.

There is  concern when  seeing a sudden increase in the number of floaters.  The concern is whether a retina tear has occurred. This concern is heightened if a denser shadow in the vision has occurred anywhere in the vision.  In such an instance, an eye check by an ophthalmologist is required.

Treatment

If an eye check does not find a retinal tear or retinal detachment, no treatment is required. Often, the floaters and flashes will reduce in number and frequency over time. However, a retinal tear will require treatment with laser. A retinal detachment will require major eye surgery.

Age related Macular Degeneration (AMD)

Age related Macular Degeneration (AMD) is a major cause of blindness in the developed world. It affects older people in one or both eyes.

AMD affects the macula of the eye. The macula is the part of the retina which is used for fine central vision. When the macula is affected, central vision is loss. Peripheral vision, which does not see so clearly as central vision, is preserved.

Central vision loss from AMD

Central vision loss as may occur in age-related macular degeneration. Credits: AAO

There are 2 types of AMD. Dry and Wet AMD.  Both types can cause blindness but vision loss with wet AMD is more sudden.

In dry AMD there are changes in the macula called drusen and thinning out of the macula layer called geographic atrophy.

Dry AMD

Dry Age-related macular degeneration showing drusen. Credits: AAO

In wet AMD, there are changes such as bleeding, leakage of fluid and swelling at the macula. Ultimately, scarring occurs and leads to vision loss.

Wet AMD

Wet Age-related macula degeneration showing a sub-retinal neovascular membrane. Credit: AAO

Treatment of Age related Macular Degeneration

Early in the disease, treatment consists of regular injections into the eye of medicines called anti-vascular endothelial growth factor (Anti-VEGF).  Several injections spread over months may be required and  for a few years.

Some forms of AMD are also treated with lasers and special injected medicine in what is called photodynamic therapy (PDT). Sometimes, steroids are also injected into the eye.

If one eye is severely affected, special eye vitamins are taken to reduce the occurrence of AMD in the other eye.

If both eyes are severely affected, visual rehabilitation with low vision devices is the treatment.

How to prevent blindness from Age related Macular Degeneration

If you have signs of dry AMD in any eye, you should monitor your vision regularly with an Amsler Grid. An Amsler Grid is a piece of paper printed with small squares.

Amsler Grid

Amsler Grid. Credit: AAO

Cover one eye. With the other eye, look at the centre of the grid.

If you see any area of the printed squares with distortion or wavy lines or you do not see some small squares, you should seek medical assistance immediately.

Glaucoma: a major cause of blindness worldwide

Glaucoma is the most common cause of irreversible blindness and visual impairment in the world.

It is a group of eye diseases where there is damage to the nerve of the eye. The nerve of the eye carries vision from the eye to the brain. Damage to this nerve, called the optic nerve, results in vision loss.  We call the vision loss a visual field defect. This damage is often progressive and left untreated results in blindness.

The major risk factors to have the eye disease include raised eye pressure, older age, cardiovascular disease, myopia and diabetes mellitus.

Early damage leads to vision loss but. Unfortunately,  this is seldom noticed by the individual.  For that reason, individuals often present with severe vision loss or blindness.

Fortunately, blindness can be prevented by early detection and treatment.  Treatment is meant to reduce the pressure of the eye. The eye pressure reduction is by means of eyedrops, surgery or laser.

Glaucoma treatment

Eyedrops used include beta-blockers, carbonic anhydrase inhibitors, prostaglandin analogues and alpha agonists.

Glaucoma eyedrops - to lower eye pressure

Glaucoma eyedrops – to lower eye pressure. Credits: AAO

 

 

 

 

 

 

 

Surgery includes trabeculectomy, aqueous shunt device implantation and minimally invasive glaucoma surgery.

Glaucoma Surgery - Trabeculectomy

Glaucoma Surgery – Trabeculectomy. Credits : AAO

 

 

 

 

 

 

 

Lasers include laser peripheral iridotomy and selective laser trabeculoplasty.

Laser Surgery for Glaucoma

Laser Surgery for Glaucoma. Credits : AAO

 

 

 

 

Types of glaucoma

The two main types are primary open angle glaucoma and primary angle closure glaucoma. Other types  are called secondary glaucoma.  These are due to inflammation, trauma, steroids, diabetes mellitus and other causes. Irrespective of the cause, treatment is still directed by treating the cause where possible and reduce the eye pressure.

Prevention

Finally,  what is important to know is prevention is key. Prevention of vision loss is by early detection. The best way is by regular eye screening by an eye doctor. Screening  is recommended 2 to 4 yearly after the age of 40.  If there is a family member with glaucoma, eye screening should be 2 yearly.

 

 

Stroke and the eye: vision loss

Stroke

A stroke is said to occur when the brain does not function properly because it does not receive enough blood supply. Death of brain cells occurs.

Different parts of the brain control different body functions. If the particular part of the brain that controls a certain function does not receive it’s blood supply, that body function will be affected.

Risk factors for stroke include older age, hypertension, diabetes, smoking, high cholesterol and disturbances of heart rhythm. Strokes can be of 2 main types, ischaemic (most common type) or haemorrhagic strokes (less common).

Vision

Left hemianopia in the right eye

When the posterior circulation of the brain is affected by a stroke and the occipital lobe is involved, vision will be affected. It is possible that only the vision is affected without other features.

When the occipital lobe is involved, vision  in each eye is affected in a pattern called a “hemianopia”.  In the case of a left hemianopia (see image to right representing right eye vision), the vision to the left of the vertical midline is affected.  Strokes cause a homonymous hemianopia meaning that both eyes are affected. The vision loss may not be apparent to the affected person. They may notice that they bump into objects or may be found by chance during a check by a healthcare professional.

These stroke related vision problems have effects on reading, driving ability and many other aspects of daily living.

Vision recovery after stroke

One-fifth of patients may make a full recover in the first month. Fifty percent will have some improvement over the first month. Most of the recovery occurs within the first 2 months post stroke but further recovery is unlikely after 6 months.

References:

Goodwin D. Homonymous hemianopia: challenges and solutions. Clinical Ophthalmology 2014.

Diabetes Mellitus and the eye

Diabetes Mellitus

Diabetes Mellitus is a common condition where there is poor blood sugar control.

This results in damage to the blood microcirculation to many organs in the body e.g. the kidneys.

Unfortunately, diabetes mellitus also affects the eye. In fact, it is one of the most common causes of irreversible blindness in the western world.

Diabetic retinopathy

When diabetes mellitus affects the eye, it is called diabetic retinopathy.

Longer duration of being diabetic, poorer control of diabetes, hypertension and high cholesterol all make it more likely that diabetic retinopathy will develop.

Proliferative diabetic retinopathy

Proliferative diabetic retinopathy with new vessels at the optic disc. Credits: AAO

Doctors classify diabetic retinopathy into a non-proliferative and proliferative form. ‘Proliferative’ refers to the growth of abnormal blood vessels at the back of the eye, called the retina. These abnormal blood vessels are fragile and can bleed and cause the eyeball to be filled with blood.

 

 

 

Diabetic maculopathy. Credits: AAO

Diabetic maculopathy. Credits: AAO

The part of the eye that provides or serves the sharpest vision is called the macular. When it is affected by fluid leakages from leaky blood vessels due to diabetes, it is called diabetic maculopathy. Diabetic maculopathy is a common cause of visual impairment in the world.

Fortunately, diabetic retinopathy can be prevented with good blood sugar and blood pressure control. Early detection can also prevent serious visual impairment.  A yearly eye check is recommended.

 

Treatments include laser treatment (focal, grid and panretinal photocoagulation) and anti-vascular endothelial growth factor (VEGF) injections into the eye.

Rarely, surgery called vitrectomy is required to either remove blood in the eye or to facilitate removal of fibrous membranes that form on the retina.

Zika virus causes conjunctivitis

Zika virus conjunctivitis

The Zika virus hit the news headlines in 2016 for causing birth defects, e.g. microcephaly, in women infected during pregnancy.

It is a mosquito borne Flavivirus.

The acute symptoms of infection are fever, headache, rash, joint pains and red eye (conjunctivitis). There should be a history of travel within 2 weeks to a country with a Zika outbreak.

An increase in the number of people with Guillain-Barre syndrome, a condition causing paralysis, is thought to be also  linked to Zika outbreaks.

It has also been reported to have caused macular atrophy in children affected by infection by Zika virus during pregnancy.

Preventive measures include destroying breeding grounds of the Aedes mosquito, use of mosquito netting and repellants.

No specific treatment is needed for the conjunctivitis.

References:
Zika virus in Brazil and macular atrophy in a child with microcephaly

Dry Eyes

Dry eyes is a very common eye condition where there is insufficient tears to wet the surface of the eye and keep it moisturized.

The symptoms include sensation of dry eyes, itchy eyes, eye discomfort, tired eyes, red eyes and on and off blurring of vision. Paradoxically, dry eyes may present with excessive tearing.

It is more common with advancing age and menopause in women but can also be due to other conditions such as

  • Sjogren’s syndrome,
  • rheumatoid arthritis,
  • systemic lupus erythematosus,
  • thyroid eye disease,
  • long term contact lens wear,
  • long term eyedrop use,
  • after chemical injuries to the eyes,
  • severe drug allergies which have affected the eye e.g. Stevens Johnson Syndrome
  • certain medications
  • post laser refractive surgery

Dry Eyes treatment

Dry eyes are mainly treated by the use of lubricant eye drops and eye ointments.

dry eyes- applying eye drops

Dry eyes: applying lubricant eye drops. Credit: AAO

In severe cases, the use of ciclosporin eye drops to increase tear production may be helpful. Punctal plugs are also sometimes used.

Environmental modifications that may be helpful include reducing direct exposure of the eye to drafts from fans and air conditioners and reducing the use of dehumidifiers.

Cataract definition

Cataract definition

The natural lens of the eye is in the front of the eye. It has an important function to focus light entering the eye from varying distances onto the retina.

Lens position in the eye

The lens of the eye is in the front of the eye (blue structure on the right in diagram). Credits: AAO

A cataract is a clouding of this natural lens of the eye. When we are born, the lens of the eye is usually clear. As we get older, the lens becomes cloudier.

cataract

Top: Clear lens when born. Bottom: Brown lens in older eyes. Credit: AAO

There are different types of cataract. The main 3 types are nuclear sclerotic, cortical and posterior subcapsular. If the entire lens is involved by cataract, it is called a mature cataract.

Mature white cataract

Mature cataract: the entire lens has become involved by the cataractous change and become white

The main cause of cataract is ageing. Other common causes include injury to the eye, long term steroid use, radiation exposure and prolonged ultraviolet light exposure. Diabetics tend to develop cataract earlier. Previous eye surgery or eye inflammation may lead on to cataracts too.

The symptoms of cataract include blurring of vision, dulling of colors, glare, change in spectacle power and eye pain (lens- induced glaucoma).

To prevent cataracts, protection from ultraviolet light is suggested e.g by wearing sunglasses.  Early cataracts may be initially treated by changing glasses or contact lenses. The treatment of more significant cataracts is by cataract surgery. Evidence is lacking that eyedrops can prevent cataract worsening. Some eyedrops like glaucoma eyedrops can cause cataracts with prolonged use.

Myopia definition

Myopia Definition

In myopia or short sightedness, objects in the distance are blur to the viewer but objects that are near are clear. Optically, objects in the distance are focused in front of the retina of the eye.

Emmetropia

Normal eye: distant light rays are focused on to the retina. Credit: AAO

myopia definition

Myopic eye: distant light rays are focused in front of the retina. Credit: AAO

Myopia tends to develop during childhood and is a result of elongation of the eyeball. The increase of myopia slows down after puberty. Children who spend more time outdoors are thought to be less likely to develop myopia. In older people who develop myopia in their twilight years, the cause is development of cataract (index myopia).

The condition is called high myopia when the power is above -6 diopters.

Myopia treatment

Myopia can be corrected by wearing glasses, contact lenses or undergoing refractive surgery. Myopia increase can be slowed down by atropine eye drop treatment. Myopia glasses lenses are plano concave in design.

myopia corrective lens

Myopic eye with concave lens in front of the eye. Credit: AAO

Myopia Complications

Myopia complications include macular degeneration, choroidal neovascularisation, retinal tears and retinal detachments. Glaucoma is also associated with the condition.

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