Conservative therapy
An important and effective treatment in which a good administration technique plays a major role. It influences the effectiveness of the medication and ensures that it is administered safely and as gently as possible. The duration of action of eye drops is relatively short, as the tear film is renewed within a few minutes. Eye ointments remain in the eye a little longer. We often administer cortisone eye ointment, as cortisone has a very high anti-inflammatory effect and saves many eyes from blindness. At the same time, we administer this active ingredient for as short a time as possible, as cortisone reduces the regeneration of the cornea and increases the risk of infection. Particularly in the case of the horse's large cornea, frequent and repeated treatment with anti-inflammatory medication can therefore lead to degenerative changes, subsequent calcifying inflammation and serious infections. This is particularly the case in the warm summer months. Here, too, we try to administer and recommend as few doses as possible. If frequent doses are necessary, we administer them conscientiously, as gently as possible and at high frequency while monitoring the patients in the clinic.
At the moment we use a chlortetracycline eye ointment approved for animals for slightly infected or larger corneal defects. Superficial epithelial defects can be treated with heparin or hyaluronic acid preparations, avoiding the use of antibiotics, provided that good monitoring is possible. Deep corneal ulcers carry the risk of being infected with fungi and/or pseudomonads (bacteria), which can cause the corneal tissue to melt quickly and even break through. In these cases, reserve antibiotics that penetrate the cornea well and antifungal agents must sometimes be used by repurposing the medication. Examples of antibiotics that can be used for this include the active ingredients tobramycin, levofloxacin and ofloxacin, which should only be used after resistance testing and only in exceptional cases. Antifungal agents such as miconazole, voriconazole or nystatin are usually not available commercially as eye medication. In this case, preparations must be repurposed or eye ointments must be manufactured by pharmacies. We reject the systemic administration of doxycycline for the treatment of eye diseases.
In rare cases, swelling of the mucous membrane of the nasolacrimal duct leads to blockages and a subsequent tear trail. Rinsing the nasolacrimal duct with sterile saline solution or balanced salt solution from the nostril can clear this channel. Subsequent administration of anti-inflammatory (eg cortisone) and decongestant eye drops (eg tetryzoline) can reduce swelling of the mucous membrane and keep the duct open.
This form of administration is ideal if frequent administration of eye medication is necessary. In particular, horses that are wary due to pain or horses whose eyes are covered by a protective head bandage can be treated without having to touch the eye.
In cases of treatment-resistant or recurring corneal diseases, we often rely on the healing effect of blood vessels growing into the cornea. This allows many corneal diseases to be cured permanently and operations to be avoided.
In many cases, we use mitomycin for corneolimbal squamous cell carcinomas, taking safety precautions (gloves, eye protection, administration via catheter). This is a one-week follow-up treatment 3-4 times a day after surgical removal of the tumor. Several treatment sequences with a weekly break are also possible. Equine sarcoids are sometimes treated with cytostatics before, during and/or after laser surgery. On the eyelid, we also carry out combination therapies for squamous cell carcinomas and equine sarcoids, consisting of cytostatic injections and surgical laser therapy with a CO2 laser followed by photodynamic therapy (indocyanine green with an 810 nm diode laser).
Surgical therapy
Here, superficial layers of callus are gently removed. This can be done using a diamond bur or other blunt or sharp instruments. The diamond bur should not be used on horses for deep or incipiently infected defects. It is more for refreshing the wound edge in non-healing and non-infected callus defects.
corneal surgery
Keratectomy is the surgical removal of layers of the cornea. It is useful for removing eosinophilic deposits, calcifications, dead or demarcated corneal tissue and non-healing corneal wounds. In the case of severely infected wounds, particularly fungal infections, it must be considered whether a conjunctival flap is also necessary.
corneal surgery
In this procedure, the conjunctiva is mobilized and usually sewn onto the infected wounds after a previous keratectomy. This creates a blood vessel supply directly to the affected area, which can be used to ward off germs and build up healthy tissue. In the case of endothelial diseases or degenerative corneal diseases, e.g. corneal dystrophy in Friesians, a conjunctival flap can lead to stability and permanent freedom from irritation of the eyes.
corneal surgery
Here, after the superficial corneal layer (epithelium) has been removed, riboflavin is dripped onto the corneal tissue. This penetrates to a depth of around 300 µm. UV light is then held onto the area soaked in riboflavin using a special, very homogeneous light source. Depending on the energy output and duration of application, stabilizing, anti-enzymatic and/or antibacterial effects are achieved. The protocols and effectiveness, as well as the benefits and duration of healing in horses, are still being researched. One indication may currently be in the case of a developing corneal ulcer in order to avoid surgery. A stabilizing effect is possible in the case of corneal dystrophy in Friesians, but I currently recommend conjunctival flap surgery.
corneal surgery
In the case of abscesses located deep in the cornea, a transplant of corneal tissue may be necessary. If possible, only the deep, diseased layer is removed and replaced (lamellar). In some cases, all layers must be replaced (perforating).
corneal surgery
In equine glaucoma, there is an irreversible disruption of the drainage of eye fluid, so that the intraocular pressure increases when fluid is supplied or produced normally. Laser light with a wavelength of 810 nm penetrates the white sclera (the sclera of the eye) and is absorbed by the ciliary body tissue directly underneath. This partially destroys the tissue that produces eye fluid, so that eye fluid production can adjust to the disruption of drainage.
glaucoma surgery
Here, the vitreous body is rinsed. The benefit lies in the healing of an intraocular leptospira infection, which leads to a certain form of ERU (ERU: equine recurrent uveitis, "periodic eye inflammation", moon blindness). In addition, damaging deposits are removed from the eye. Access to the vitreous body is created using laser surgery.
vitreous surgery
Lens surgery in horses is particularly helpful for foals that have congenital or juvenile lens opacities and are unable to orient themselves. The operation is technically feasible in adult horses. However, the risks of retinal detachment are high, even after an operation without complications. In this case, the costs and benefits must be weighed up on a case-by-case basis. Access to the vitreous body, with the option of introducing BSS to maintain intraocular pressure, is a good idea.
surgery on the lens
This is a fluid-filled cavity surrounded by thin tissue at the upper or lower edge of the iris. The cysts can become so large that they impair vision or the cornea becomes cloudy and irritated from the inside. A relatively simple method of treatment is transcorneal laser application with the aim of creating a hole or several holes so that the cyst drains and becomes smaller.
cyst surgery
Tumors located in the angle between the iris and the cornea can be brought out and removed by partially removing the iris through an incision close to the edge of the cornea.
tumor surgery
Another less invasive form of therapy is photodynamic therapy. It can be used in particular for eyelid margin or conjunctival tumors. Here, a dye is applied to or in the affected area. The dye accumulates particularly in tumor cells. After irradiation with a light source that matches the dye, e.g. diode laser, different effects occur in the tissue, e.g. cell-destroying and vascular-sclerosing reactions, which leads to tumor regression.
tumor surgery
For example, in the case of eyelid margin melanoma, it is sometimes necessary to remove the tumor together with the eyelid margin. To prevent the cornea from drying out, the eyelid margin can be largely restored using eyelid surgery.
tumor surgery
The CO2 laser is used to remove tumor tissue layer by layer. For tumor operations on horses, an attachment is advantageous that moves laser beams in the form of Lissajouse patterns homogeneously and at the same time effectively over surfaces.
tumor surgery
This laser is particularly well suited for making tissue cuts using a laser fiber.
tumor surgery
