Contact lenses are used increasingly to provide pain management and to promote corneal healing. There are animal specific bandage lenses as well as human bandage lenses on the market. The human bandage lenses can be used in animals.
The sizes of the bandage contact lens are as follows:
- Human bandage contact lenses are typically 14mm Diameter/8.6 Base Curve/0 Power
- Dog bandage contact lenses range from 15.5 to 22mm Diameter/8.5 to 11.8 Base Curve/0 Power
- Cat contact lenses range from 14 to 18mm Diameter/8.3 to 9.4 Base Curve/0 Power
Contact Lens Basics
When using a contact lens, a topical antibiotic drop should be applied at least twice daily. Using the antibiotic prevents infection secondary to the contact lens use. The contact lens contains microscopic holes to allow medication to penetrate and reach the cornea. Once placed, the contact lens does not need to be removed and cleaned. Most contact lenses are used for two weeks, however, contact lenses may be left in place for two to three months. If a contact lens falls out of the eye, do not replace the same lens.
Depending on the disease that is being treated and the patient’s clinical signs, a new contact lens may be placed. Do not place a contact lens if there is significant mucoid, purulent ocular discharge, or if there is an infected or deep corneal ulcer.Using a topical tear supplement after placing a contact lens may cause the lens to fold on itself or slip off the cornea.
Ocular Diseases Treated with Contact Lenses in Dogs and Cats
Common ocular diseases treated with contact lens placement are indolent ulcers, superficial ulcers, and corneal calcium degeneration. Sometimes contact lenses will be used for deep corneal ulcers or descemetoceles. A consultation with an ophthalmologist is best before attempting to place contact lenses in those patients.
- Indolent Ulcers. Also known as recurrent ulcers, these are a specific type of corneal ulcer in which the outer layer of the cornea (the epithelium) will not adhere to the underlying layer (the stroma). This condition often occurs spontaneously in dogs over six years of age. Certain breeds of dogs (Boxers) are more commonly affected. Regardless of the cause, these ulcers can persist for months if left untreated, causing pain and scar formation. Contact lenses are placed after a corneal debridement and grid keratotomy are performed. They provide comfort and protect the fragile epithelium during healing and have been shown to decrease the amount of time it takes to heal an indolent ulcer.
- Superficial Non-infected Ulcers. These ulcers can be treated with a contact lens (See Figure 1). The lens provides pain management and protects the corneal epithelium. A contact lens can be used to protect the cornea from irritation due to ectopic cilia prior to surgical excision. Contact lenses may be placed in entropic animals to provide pain management prior to surgical correction.
- Superficial Ulcers Cats with a High Risk of Corneal Sequestrum Development. Sequestrums can be painful and many require surgical excision. Placement of a contact lens can prevent sequestrum formation as well as facilitate corneal healing. Sometimes pigment will adhere to the contact lens rather than in the cat’s cornea.
- Corneal Calcium Degeneration. Age, breed and underlying diseases (such as Diabetes Mellitus, Hyperadrenocorticism, Hypothyroid and Renal Disease) cause calcium and lipid deposits to form in the cornea. These deposits (Figure 2) are often raised and cause significant corneal irritation. Contact lenses can be placed to provide comfort by creating a smoother surface for the eye. In this condition, a contact lens can be left in place for two to three months.
If the contact lens is still in place in two to three months, the contact lens should be removed and a new contact lens can be placed if indicated. In addition to a topical antibiotic to prevent infection during contact lens use, 0.02% Tacrolimus ophthalmic solution is used to lessen or smooth out the corneal deposits. Tacrolimus is recommended for corneal calcium degeneration with or without contact lens placement.
We hope these tips help you understand more how how to use contact lenses in your veterinary patients.