Dr. Christine ThyssenDr. Christine Thyssen is a veterinary surgeon with an additional qualification in ophthalmology. After her studies at the Ludwig-Maximilians-University of Munich, she worked first as an assistant, then as a senior physician at the Surgical Veterinary Hospital of the LMU. She then ran her own practice in Gut Lichtenberg, Scheuring. Since 2016, Dr. Christine Thyssen senior physician for ophthalmology in the veterinary clinic Gessertshausen. Specialties: Diagnostics and therapy of eye diseases, operations also intraocular (z.B. cataract), examinations for hereditary eye diseases. The specialist veterinarian is a member of the "Dortmunder Kreis" (DOK).
Anicura small animal specialists Augsburg GmbH
The "dry eye" in dogs – recognition and therapy
The "dry eye", also
Keratoconjunctivitis sicca or Sicca syndrome is a common eye disease in dogs. The problem: The protective tear film in the eye fails. As a consequence, painful inflammations with consequential damages may occur. Timely treatment is therefore important. Promises good therapeutic results.
Why the tear film is so important!
The tear film in the eye is composed of three components: the Lipid layer, of the aqueous component (largest proportion with 90-98 %) and the Mucin/mucus layer. Together with nerves and eyelids it protects conjunctiva, cornea and ocular surface by constant moistening and nourishment. With each blink of the eye, a very thin film of moisture is distributed on the cornea and at the same time foreign material (z.B. dust, plant particles) but also bacteria and viruses are carried away. Via the nasolacrimal duct, impurities are carried away from the eye with the lacrimal fluid. At the same time, a healthy tear film is important for the optics, i.e. for the whole vision.
What causes the disease?
In the case of "dry eye" there is a Dysfunction of the tear film, usually due to deficiency of the individual components or excessive evaporation. As a result, changes occur in the conjunctiva and cornea. A distinction is made between a quantitative disorder in the absence of the fluid and a qualitative disorder in the deficiency of the lipid and mucin components. Why it comes to a disturbance, can have various causes: Often they are race-related, i.e. congenital. But also a previous eye disease or. Infection can trigger the problems. Likewise, the cause may be related to systemic diseases, d.h. autoimmune, hormonal, neurogenic causes.
What happens when the eye is too dry?
Like the causes, the clinical symptoms of sicca syndrome are varied. In early stages, the eyes appear red, with varying degrees of watery or mucous to purulent discharge. Often "only" in the morning the sticky eyes are noticeable. Since the signs in the early stage are unspecific, there is a risk to confuse the disease with a primary bacterial conjunctivitis. In advanced cases, pain becomes noticeable, there is severe eyelid twitching. The conjunctiva is highly red, sticky and thickened. The cornea appears dull, rough, cloudy to opaque. If no therapy is done, cellular infiltration and brown to black pigmentation and ingrowth of vessels will occur. Ulceration to perforation of the cornea may also occur.
How dry eye is diagnosed. Several tests are available for this purpose:
1. Slit lamp examination of the eyelid margin, conjunctiva, cornea and the entire ocular surface.
2. Schirmer tear test (STT) to measure the aqueous component of the tear film (STT 1: measurement of irritant tear production, STT 2 measurement of basal tear production).
3. A Vital staining with fluorescein stains the precorneal tear film and the epithelial defects, a Vital staining with lissamine green Stains superficially damaged cells.
4. Tear film break-up time examination with dye (fluorescein) under the blue filter of the slit lamp.
Dry eye has many faces: acute, highly painful, an emergency – moderate, almost unnoticed, nevertheless associated with pain and consequential damage to the eye. Individual treatment is always necessary!"
What successful therapy looks like.
The aim of the therapy is a sufficient and stable moistening of the ocular surface. This relieves pain, improves the quality of life and reduces consequential damage to the eye. This is achieved by replacing the tear fluid and stimulating its production. Depending on the severity, the tear fluid must be supplemented artificially. Basically: rather too much than too little. Here a multiplicity of tear substitute drops/gels/ointments is available, it is recommended to use preservative-free preparations. Depending on the severity, low-viscosity preparations up to highly viscous gels and ointments are used. An individual adaptation to the patient is crucial.
Good eyelid and eye hygiene is also necessary by cleaning the area around the eye, the eyelids and rinsing out the mucus from the conjunctival sac before applying the medication.
In addition, the natural tear production are stimulated. Immunomodulating substances such as topical ciclosporin A and tacrolimus lead to increased tear production and improvement of keratopathy and decrease of symptoms by local release of neurotransmitters. Cholinergics are suitable in selected cases to activate tear secretion via the parasympathetic nerve. Supportive measures can be omega-3 fatty acids are fed, which are described as having anti-inflammatory effects. Local antibiosis and anti-inflammatory therapy with local corticoids are necessary in some cases. Resistance tests and strict consideration especially with corticosteroids are necessary.
If local therapy is not successful, surgical intervention can be considered. In this case, the salivary gland excretory duct (parotid duct) is transplanted into the conjunctival sac. In conclusion, even if the symptoms of dry eye are initially discrete and inconspicuous, it should be diagnosed and treated as early as possible.