Diabetic retinopathy is a potentially sight-threatening complication that affects people with both type 1 and type 2 diabetes. Diabetic retinopathy affects the small blood vessels in the retina, at the back of the eye, causing them to leak or become blocked. This can lead to blurred vision and even blindness if left untreated. The mainstay of treatment is laser, or injections into the eye, or a combination of both.
There is an ongoing, significant rise in the number of people in Ireland with diabetes – particularly type 2, due to obesity – so diabetic retinopathy is no longer a rare complication. In fact, it is the leading cause of blindness in adults under the age of 65. More than 18,000 people in Ireland are estimated to have diabetic retinopathy, which causes on average one person with diabetes to go blind every week.
It is estimated that 25 per cent of people with type 1 diabetes will have some degree of diabetic retinopathy five years after their symptoms develop, according to the HSE. In the case of type 2 diabetes, 25 per cent of people who do not require insulin will have some degree of diabetic retinopathy five years after the onset of symptoms. The figure is higher for people who require insulin (an estimated 40 per cent who develop diabetic retinopathy at five years).
A national screening programme for diabetic retinopathy, called Diabetic RetinaScreen, was launched on a phased basis in 2013. The programme offers regular eye screening to people with diagnosed diabetes, aged 12 years and over, who are registered with the programme. People with diabetes are commonly not aware that it can cause visual problems, according to William Power, a consultant ophthalmologist at the Royal Victoria Eye and Ear Hospital (RVEEH) in Dublin.
“In addition, diabetes patients develop cataracts more frequently and at a younger age, often in their 40s and 50s. Diabetes type 2 patients also develop different problems with their retina compared with type 1 diabetics, and diabetics are also at an increased risk of glaucoma and other eye conditions,” says Power, who is also the incoming president of the Irish College of Ophthalmology (ICO).
Underlying systemic diseases
Autoimmune diseases such as rheumatoid arthritis and lupus can cause dry eye and reduced vision.
Sjögren’s syndrome, a chronic systemic inflammatory autoimmune disorder that causes dry mouth and decreased tear production leading to dry eye, can occur by itself or in conjunction with other autoimmune diseases.
Multiple sclerosis (MS), a chronic disease that attacks the central nervous system, can also cause eye problems to develop in patients.
Blurred or reduced vision and painful or involuntary eye movements can develop after a person has been diagnosed with MS, although sometimes eye problems are the initial manifestation of the disease.
“What we would see in that case would be optic neuritis, where the person is having inflammation of the optic nerve, and characteristically loses vision over a period of a few days – not complete but substantial visual loss – and it tends to return over a few weeks and can be associated with discomfort and painful eye movements,” Power explains.
An MRI scan is commonly performed on these patients and, depending on the results, they can be referred to a neurologist with an interest in MS to test whether they have the disease or have just experienced isolated optic neuritis.
Sexually transmitted infections
Certain sexually transmitted infections (STIs) can also cause eye problems.
It emerged at the ICO annual conference last year that a small but rising number of patients complaining of eye problems that turn out to be caused by syphilis or gonorrhoea are presenting at the RVEEH, and at hospitals and GP surgeries around the country.
Syphilis can cause blurred vision or floaters, pain in the eye, and painful sensitivity to light. In a minority of patients, gonorrhoea can cause eye swelling and weeping, or pus-filled sores to form around the eye, and these symptoms can be mistaken for standard conjunctivitis.
The underlying STIs need to be treated to resolve the eye issues and, if left untreated, can cause more serious, long-term visual problems.
Retinal detachment is a rare but very serious eye complication that requires immediate treatment to prevent permanent vision loss or blindness. Retinal detachment occurs when the retina pulls away from the layer of blood vessels that provide it with oxygen and nourishment. Trauma, retinal tears and complications from eye surgery can cause retinal detachment, while people with diabetes, poor eyesight and a family history are more at risk.
“Retinal detachment is also associated with people who are quite short-sighted, so the higher your prescription in terms of your short-sightedness, the greater your risk of developing retinal detachment,” says Power.
Signs of retinal detachment include the sudden onset of “floaters” – little squiggles or dots – in the visual field. “When we see somebody with a new onset of floaters, we do a good examination of the retina to make sure there are no holes or tears, because if we spot a tear we can laser around the tear and seal it so fluid can’t get in and cause a retinal detachment,” he says.
If an actual retinal attachment has occurred, immediate surgery is necessary. This is successful in restoring reasonably good vision in 90-95 per cent of cases, particularly when the surgery is carried out as soon as possible after the onset of symptoms, Power says.
The RVEEH carries out at least two emergency retinal reattachments weekly, with some planned surgery too. “We have three retinal surgeons in the RVEEH and have to provide a full 24/7 service for retinal detachments.”
Rosacea is a skin condition that causes facial redness and flushing and it can also cause dry eye, eye and eyelid redness, soreness, and light sensitivity. Known as the Celtic curse, Rosacea is very common in Ireland due to the prevalence of fair skin. “Some of the most common eye presentations in the casualty in RVEEH are because of rosacea. It can cause burning, stinging, sore eyes and can, in a minority of cases, cause serious corneal issues such as corneal ulcers and problems needing corneal transplants,” says Power.
Rosacea is incurable but can be managed, and the latest treatment involves low-dose antibiotics as well as good eye hygiene and eye drops for dry eye.
Household accidents, sporting injuries and assaults can cause serious eye and eye-socket trauma leading to vision loss or blindness. Hammering a nail or using a knife or scissors while distracted can cause serious eye injuries, while sometimes, in the construction or mechanical industries, tiny fragments of metal can become lodged in the eye. Scratching the eye while walking into a bush or tree branch is also common.
One or twice a year the RVEEH treats people who have superglued their eyelids together accidently. “My mantra is if you have a hammer in your hand and you are banging anything with it, you should have protective eyewear on,” Power says.
Burns to the eye can be caused by industrial or household chemicals, and by lime, and can have very serious outcomes. “We see chemical injuries particularly to do with an alkaline substance, anything that is caustic, from the agricultural or construction industry, particularly from lime. A bad lime burn can cause blindness, so a chemical injury is an acute emergency and they need to irrigate the eye. So if that happens, stick your head under the tap and rinse the eye really well, then go to an eye casualty immediately,” Power says.
Acquired brain injury
People commonly believe that visual ability is simply linked to the eyes, but they are just part of the complex visual pathway. Eyesight can be negatively affected by an acquired brain injury (ABI) or a neurological medical condition. ABI-related visual issues can occur due to severe head trauma, stroke, tumours, certain diseases such as MS, and as a result of neurosurgery.
Dr Patricia Logan is a consultant ophthalmic surgeon specialising in neuro-ophthalmology at Beaumont Hospital in Dublin. Speaking at a recent Royal College of Physicians of Ireland (RCPI) meeting about traffic medicine, she said neuro-ophthalmology issues typically have a rapid, sudden onset and can occur in young, otherwise healthy patients with good vision and can significantly affect driving ability.
Sudden onset of diplopia, ie double vision, loss of visual acuity and field, and oscillopsia (in which objects in the visual field appear to oscillate, ie jump or move) are the main visual issues that neuro-ophthalmologists deal with, Logan told the meeting.
Diplopia is commonly treated with prism therapy and occlusion therapy or occasionally eye muscle surgery, depending on the amount of muscle damage, but not all patients will recover binocular vision, according to Logan.
Many stroke patients with visual field loss may recover it within six months, although if they don’t significantly improve within six months they are not likely to improve any further. So while many ABI issues will resolve with time or are treatable, some patients will never be able to drive again, which may impact on their ability to work and this can be devastating for them, Logan noted.
The third edition of Ireland’s Medical Fitness to Drive Guidelines were launched in March.
Paediatric eye conditions
The most common eye conditions in children are vision deficiencies that require correction with glasses, or strabismus, a visual problem in which the eyes are not aligned properly and point in different directions. This affects about one in 20 children and usually develops before a child is five.
If strabismus is left untreated, the brain will eventually suppress or ignore the image of the weaker eye, resulting in amblyopia (‘lazy eye’ when an eye is unable to focus on details) or permanent vision loss. Longstanding eye misalignment can impair the development of depth perception or the ability to see in 3D.
Less common paediatric eye conditions include retinopathy of prematurity (ROP), a disease of the eye that occurs in premature babies. ROP can cause the retina to detach from the back of the eye, leading to blindness, explains Prof Michael O’Keefe, consultant ophthalmologist at Temple Street Children’s University Hospital, and Ireland’s foremost paediatric eye expert.
Some cases of ROP are mild and correct themselves, but others require treatment with laser eye surgery to prevent vision loss or blindness, though anti-VEGF (vascular endothelial growth factor) injections are now emerging as a new viable treatment option.
Babies who are born before 30 weeks’ gestation have their eyes screened and if ROP is detected, these babies require surgery as soon as possible, within 36 to 72 hours. O’Keefe treats about 25 babies a year with ROP. “Ninety per cent of these babies who are treated for ROP do well, but about 10 per cent can develop significant vision loss,” he says.
Other serious eye issues in children include tumours and retinoblastoma, a rare cancer of the eye. Temple Street is the all-Ireland treatment centre for retinoblastoma and treats about eight cases of the disease annually.
Retinoblastoma can occur in one or both eyes and about half of cases require the eye to be removed. Over the course of his career O’Keefe has had to remove both eyes in two children diagnosed with aggressive retinoblastoma. “If parents see what is known as a white reflex in photos of their baby, instead of the normal red reflex, ie ‘red eye’, they should get their baby checked out urgently as this can be an indicator of retinoblastoma,” he says.
Cataracts are associated with ageing but can develop in young children too. O’Keefe treats about 50 cases of paediatric cataracts a year. Paediatric cataract cases can be congenital, and have to be treated within eight weeks, or developmental, where they develop spontaneously for no known reason; there is a higher incidence in children with Down syndrome or certain metabolic disorders.
About once a month, O’Keefe treats a child with severe accidental eye trauma. Occasionally, young children suffer severe eye burns caused by liquid laundry detergent capsules, so these should be stored safely.
AssistIreland.ie, provided by the Citizens Information Board, contains information about living aids, mobility aids, assistive technology and products for people with disabilities and older people. For products related to visual impairment, see assistireland.ie/eng/Products_Directory/ Blind_and_Low_Vision/
Fighting Blindness is a patient-led organisation funding research into treatments and cures for blindness. It supports people experiencing sight loss, and their families.Fighting Blindness, 3rd Floor, 7 Ely Place, Dublin 2. Tel: 01-6789004. fightingblindness.ie Irish Guide Dogs for the Blind is the national charity dedicated to helping people who are blind or vision impaired and families of children with autism to achieve improved mobility and independence. Guide Dogs for the Blind Model Farm Road, Cork. 1850-506300; guidedogs.ie
The National Council for the Blind is a not-for-profit charitable organisation that provides support and services nationwide to people experiencing sight loss. It also helps public and private organisations ensure that their services are accessible to people who are blind and vision impaired. National Council for the Blind, Drumcondra, Dublin 9. Tel: 01-8307033/1850-334353; ncbi.ie