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If you have diabetes, you have probably already heard about retina checks. The surface of the eye gets less attention: the cornea, the tears and the eyelids. Diabetes raises the risk of dry eyes, inflammation of the eyelid margins and slow healing of the cornea. On this page we explain why this happens, what the eye doctor checks, and what can be done when home care is no longer enough.
Why diabetes affects the surface of the eye
Diabetes is a disease of the whole body, and high blood sugar levels over a long time damage small blood vessels and nerves. The surface of the eye is particularly sensitive to both of these. Major reviews of dry eye list diabetes among the factors linked to dryness, and the mechanism is made up of several parts that affect one another.
Less sensation in the cornea
The cornea (the clear window at the front of the eye) is one of the most nerve-rich tissues in the body. These nerves do not only sense: they also send a signal to the lacrimal gland to produce tears, and to the eyelids to blink. In long-standing diabetes the nerves can be damaged, much like the nerve damage in the feet. The result is fewer tears and less blinking, but also less sensation. So some people with diabetes feel only mild dryness, while the examination shows real damage to the surface of the eye.
Slow healing of the top layer of cells
The top layer of the cornea is called the epithelium. It normally renews itself quickly and heals within a short time after a scratch. In diabetes the epithelium tends to be more fragile, and it heals more slowly. In severe cases a defect forms that does not heal for a long time, a condition called neurotrophic keratopathy (damage to the cornea caused by a reduction in its nerve supply). This condition is relatively rare, but it is important to recognise it early.
Inflammation of the eyelids and the meibomian glands
In the eyelid margins there are small glands called meibomian glands, which produce the oily layer of the tears. This layer stops the tears from evaporating quickly. In people with diabetes, blockage and inflammation of these glands (MGD, meibomian gland dysfunction) and inflammation of the eyelid margins (blepharitis) are more common. When the oil does not flow out properly, the tears evaporate quickly and the eye dries out.
Which symptoms to look out for
- Burning, itching or a gritty, sandy feeling in the eyes.
- Vision that blurs and clears after blinking, especially at a screen or when reading.
- Red eyelids, scales at the base of the lashes or sticky eyelids in the morning.
- Watery eyes, paradoxically, as the eye's reaction to dryness.
- A scratch or wound in the eye that heals more slowly than expected.
It is important to remember: because of the reduced sensation, having no symptoms does not guarantee that the surface of the eye is healthy. Changes in blood sugar levels can also cause fluctuations in vision that are not related to dryness, so it is worth reporting any change to the doctor.
Why dryness is sometimes hard to recognise
In people without diabetes, significant dryness usually causes clear symptoms, and they go to the doctor. In diabetes the picture can be the reverse: the more the corneal nerves are damaged, the weaker the symptoms may be, even when the surface of the eye is damaged. That is why some people discover the dryness only at a routine eye examination, or after a small scratch that does not heal.
Blurred vision can also be confusing. It can come from dryness, from changes in blood sugar levels that affect the lens of the eye, from a cataract or from involvement of the retina. Only a proper examination can tell them apart. If your vision changes, do not assume in advance that it is just dryness.
After eye surgery
People with diabetes have quite a few eye operations and treatments: cataract surgery, laser treatment of the retina and injections into the eye. All of these can make existing dryness worse for a while. The drops used after surgery, especially if they contain a preservative, can also irritate the surface of the eye. More on this on the preservative-free drops page.
Before cataract surgery, untreated dryness can affect the measurements used to choose the lens. After surgery, slow healing of the epithelium can prolong recovery. So it is worth telling the surgeon about dryness or eyelid inflammation, and treating them in advance as they advise.
What you can do at home
- Preservative-free lubricating drops, as needed, and especially when you use them several times a day.
- Warming and cleaning the eyelids when there is a meibomian gland or blepharitis component. How to do this properly is explained on the warm compresses for the eyes page.
- Breaks from screens and full, conscious blinking, because in diabetes blinking may be less frequent.
- Blood sugar control together with your diabetes care team, as part of looking after the health of the whole eye.
- Care with rubbing your eyes and with any object that could scratch the cornea, because scratches heal more slowly.
When home care is not enough: what the specialist checks
If the dryness continues despite home care, or your eye doctor has seen signs on the surface of the eye, a thorough assessment helps to understand which mechanism is dominant in your case. A dry eye examination usually includes:
- Examination with a slit lamp (a microscope for examining the eye) of the cornea, the conjunctiva and the eyelid margins.
- Fluorescein staining (a harmless yellow-orange dye) to see damaged areas of the epithelium and to measure how long the tears stay stable.
- Measuring the amount of tears with the Schirmer test (a thin paper strip at the edge of the eyelid).
- Assessment of the meibomian glands with gentle pressure, and a check of the eyelid margins and for Demodex (a tiny mite that lives at the base of the lashes).
- Assessment of corneal sensation, when nerve damage is suspected.
Details of the tests are on the dry eye testing page. It is important to know that these tests do not replace the diabetic retina check, which is done separately.
Treatments at the clinic
The choice of treatment depends on the findings. Alongside drops that the eye doctor may prescribe, for example anti-inflammatory drops, these are the treatments given at the clinic, as needed and after an examination:
- Meibomian gland expression: gentle emptying of blocked glands after warming.
- IPL treatment: broad-spectrum pulsed light (not a laser) that may improve the function of the meibomian glands and reduce redness of the eyelid margins.
- BlephEx treatment: thorough cleaning of the eyelid margins in blepharitis and Demodex.
- Punctal plugs: when there is a shortage of tears, they keep the tears on the eye for longer.
- Autologous serum eye drops: drops prepared from the patient's own blood, for severe dryness or an epithelium that is struggling to heal.
- Bandage contact lens: a soft lens that protects the cornea like a bandage, in selected cases and under close follow-up, because in diabetes the risk of infection calls for caution.
Coordination with your diabetes care team
Eye treatment works better when all the doctors know the full picture. Tell your eye doctor about the type of diabetes, how long you have had it and all the medicines you take. Tell your family doctor or diabetes doctor about findings in your eyes, for example reduced corneal sensation, because it may point to nerve damage in other parts of the body too. Do not stop or change a medicine by yourself.
When to see a doctor straight away: eye pain that is getting worse, a red eye with strong sensitivity to light, a white or grey spot on the cornea, a pus-like discharge, a sudden drop in vision, or a scratch in the eye that does not improve within a day or two. In diabetes a wound in the cornea can get worse and become infected more quickly, so do not wait.
Want a basic explanation first?For basic information on cleaning your eyelids at home: the guide on the Mitzmutz site
Frequently asked questions
Why do I feel less dryness than the doctor sees in the examination?
In long-standing diabetes the nerves of the cornea can be damaged, and sensation on the surface of the eye decreases. So there can be damage to the eye surface even when the symptoms are relatively mild. This is one of the reasons why an examination by an eye doctor is important even when you hardly feel anything.
Will controlling my blood sugar improve the dryness?
Good blood sugar control is important for the health of the whole eye, and it may also benefit the eye surface. However, dryness that is already present usually also needs local treatment, and does not disappear through blood sugar control alone.
Does a dry eye examination replace the diabetic retina check?
No. The diabetic retina check is a separate examination, which usually includes dilating the pupils. Keep having retina checks at the intervals set by your eye doctor, even if you are being treated for dryness.
I have diabetes and I am planning cataract surgery. Should dryness be checked beforehand?
Yes, it is worth telling the surgeon about dryness or eyelid inflammation. Treating dryness before surgery may improve the accuracy of the measurements taken before the operation and your comfort afterwards. The decision on timing is the surgeon's.
Home care not enough? We can look into it.
At the dry eye clinic in Haifa we find out what is causing the dryness and build a personal treatment plan.
Sources
- Stapleton F, Alves M, Bunya VY, et al. TFOS DEWS II Epidemiology Report. Ocul Surf. 2017;15(3):334-365.
- Bron AJ, de Paiva CS, Chauhan SK, et al. TFOS DEWS II pathophysiology report. Ocul Surf. 2017;15(3):438-510.
- Gomes JAP, Azar DT, Baudouin C, et al. TFOS DEWS II iatrogenic report. Ocul Surf. 2017;15(3):511-538.
- Zhang X, Zhao L, Deng S, Sun X, Wang N. Dry Eye Syndrome in Patients with Diabetes Mellitus: Prevalence, Etiology, and Clinical Characteristics. J Ophthalmol. 2016;2016:8201053.
- Akpek EK, Amescua G, Farid M, et al. Dry Eye Syndrome Preferred Practice Pattern®. Ophthalmology. 2019;126(1):P286-P334.
The information on this site is general only. It is not medical advice and does not replace an examination by an eye doctor.