Types of Medications for Dog Eye Diseases: A Comprehens

1. Key Medication Forms for Eye Treatments:

Eyedrops: Available in two forms, solutions and suspensions. When the tonicity of the eye drops is equivalent to a 0.720% NaCl solution, animals typically experience minimal discomfort after use. For human use, the tonicity should match that of a 1.4% NaCl solution. The ideal pH range for eye drops is between 3.5 and 10.5. The more alkaline the solution, the better it penetrates the eye, although this can compromise the stability of the medication. Eye drops usually do not contain preservatives, as these can be harmful to the eyes.

Eyedrops ointments: The drugs in ointments cannot be ionized, so their tonicity and pH are less critical. Ointments allow for a prolonged contact time between the drug and the eye tissues, and the medication remains more stable than in solutions. However, ointments can interfere more with corneal growth than drops and can also cause inflammatory reactions when the oil base is absorbed into the eye's tissues. Therefore, ointments should be avoided in cases of corneal ulcers, traumatic eye conditions, or after eye surgery until the wounds have healed.

2. Common Administration Methods for Eye Medications:

The administration of eye medications for dogs is limited by four factors: the nature of the drug itself, such as polymyxin B, which has strong nephrotoxicity and can only be used topically; the characteristics of the treatment area, such as using eye drops or subconjunctival injections for corneal treatments, while systemic medications or posterior chamber injections may be needed for choroidal inflammation; the possibility of repeat dosing, as veterinarians may only have one opportunity to administer medication in the hospital; and the required drug concentration, which can be maintained or extended through methods like increasing concentration, frequent dosing, reducing absorption rates, or disrupting the lipid layer in the epithelium to enhance drug penetration.

Eyedrops ointment: With a relatively stable drug concentration, ointments are not as frequently needed and are suitable for dogs that find it difficult to repeatedly drop eye medications. However, they are not effective for treating corneal ulcers. Clinically, they are often used to protect the cornea during anesthesia or paralysis. Generally, applying the ointment at night is more effective. Before bathing a dog, applying the ointment can prevent irritation from bath products.

Eyedrops: Easy to use and costeffective, but their effectiveness can be quickly diluted by tears, necessitating frequent administration throughout the day. Chloramphenicol eye drops are known to enter the eye quickly, but their absorption rate is not faster than other drugs in dogs with intact corneas.

Subconjunctival injection: This method allows for rapid entry of the drug into the eye's vascular system, making it suitable for most antibiotics and corticosteroids. However, it is necessary to anesthetize the conjunctiva with a proparacaine eye drop 23 minutes before the injection. For doses of 1 milliliter or more, the medication should be divided into 0.5 ml per injection point. If there is some bleeding at the injection site, there is no need to worry; it typically resolves completely within 7 days.

IV injection: In cases of intraocular inflammation, intravenous administration is necessary to achieve the required therapeutic drug concentration within the eye. Additionally, rapid reduction of intraocular pressure requires the intravenous administration of diuretics, such as 20% mannitol.

Oral and intramuscular injections: When treating eye diseases, this route of administration must consider both the absorption status and effective plasma drug concentration at the administration site, as well as the drug's ability to cross the bloodaqueous humor barrier. The goal is to ensure an effective drug concentration at the site of the eye disease.