Spontaneous Chronic Corneal Epithelial Defects (SCCEDs) treatment

One of the most frequent causes of ophthalmic pain in our veterinary patients is corneal ulceration.? Because our patients cannot give histories/answer questions, it is up to the veterinarian to identify the underlying origin.? Most non-complicated corneal ulcers should heal within 4-7 days with medical therapy alone.? For those that persist beyond this time frame, deeper investigation is indicated.

Understanding Persistent Corneal Ulcers

Persistent corneal ulcers can stem from a variety of factors including aberrant anatomy (e.g. entropion, ectopic cilia, exophthalmia), lagophthalmos due to cranial nerve defects, uncontrolled keratoconjunctivitis sicca (KCS), infection, foreign bodies, inappropriate medical therapy, and Spontaneous Chronic Corneal Epithelial Defects (SCCEDs). When facing a corneal ulcer that lingers beyond the expected healing time frame, it's crucial to identify the root cause to tailor the therapy appropriately.

One of the primary challenges in the ophthalmology field is becoming comfortable with a complete ophthalmic exam.? The more you do, the easier they become.? Look at the patient both near and far.? Beyond basic menace and pupillary light response testing, Schirmer tear test, intraocular pressure reading, and fluorescein stain are recommended as long as the globe appears stable.? A systematic approach (outward moving inward or vice versa) is important to review all ocular anatomy.? A complete ophthalmic exam in combination with history and signalment is often enough to help you arrive at a correct underlying origin.???

If a superficial ulcer is not healing appropriately, the answer is rarely to add another antibiotic.

Zooming In: Spontaneous Chronic Corneal Epithelial Defects (SCCEDs)

SCCEDs, also known as indolent ulcers, typically affect dogs older than six years, and can be seen in any breed.? They are most commonly seen in Boxers (aka Boxer ulcers), French Bulldogs, West Highland White Terriers, Welsh Corgis, Bull Terriers, Pit Bull Terriers, and Retrievers. SCCEDs are always superficial, are associated with mild to moderate pain, and have a distinctive appearance marked by redundant epithelium and often vascularization. They rarely become infected and are diagnosed after excluding other potential causes of ulceration.

Treatment Strategies for SCCEDs

Medical therapy in conjunction with a procedure is generally the answer for encouraging SCCEDs to heal.? Antibiotic therapy is needed to prevent infection and oral medications are needed to help keep inflammation and pain under control.? However, the root of the problem with SCCED healing is mechanical, and therefore a mechanical therapy is almost always required for their resolution.

These mechanical treatments include cotton tip applicator (CTA) debridement of the epithelium alone, anterior stromal puncture, and CTA debridement followed by grid keratotomy or diamond burr keratectomy.? If the former methods of therapy fail, the last resort is to perform a superficial keratectomy via scalpel under an operating microscope. The choice of treatment depends on the specific case and the success rates of these procedures can vary.? In general, grid keratotomy and/or diamond burr keratectomy are the most consistent way to resolve a SCCED.

If you have a SCCED that persists despite 1-2 attempts of mechanical therapy, referral is indicated.? If you have any doubt about your diagnosis of a SCCED, referral is indicated.

Grid Keratotomy Technique and Postoperative Care

A grid keratotomy involves creating a grid pattern over the ulcer surface with a needle.? This provides grooves for the cells to attach down to, and breaks up the acellular hyaline zone noted with SCCED ulcers on histopathology.? Preparation involves sedation (for the general practitioner), application of an ophthalmic betadine preparation, and application of proparacaine for local anesthesia.? An eyelid speculum, 0.3 mm forceps, 27 gauge needle, and numerous dry cotton tip applicators are recommended.? After the corneal epithelium has been thoroughly debrided, the grid keratotomy is performed keeping the needle bevel up at a 15-30 degree angle to the cornea. Numerous superficial grid marks are made across the corneal surface in different directions, encompassing 1-2 mm of normal cornea to encourage cell migration.? Postoperative recommendations include the use of a topical antibiotic (e.g. tobramycin), lubricant, oral anti-inflammatory, oral pain medication, and E-collar.?

Recheck in 2-3 weeks is recommended.? Color changes including blue (edema) and red (vascular) changes are common, and are usually a normal part of the healing process.? Owners should be instructed to watch for increased discomfort after the first 2-3 days, yellow-green corneal color change, and/or corneal contour changes (e.g. divots).? It is uncommon, but until healed, any indolent ulcer pre- or post-procedure can become infected.? If owners have concerns, patients should be re-evaluated as soon as possible.

Once healed, the presence of corneal scarring is highly variable.? If the ulcers were present for a long period of time prior to treatment, some corneal scarring never resolves.? In general, most scars fade or disappear within a few months of ulcer resolution.?

When Not to Perform a Grid Keratotomy

If any of the following are observed with the ulcer being treated, do not perform a grid keratotomy: stromal loss, depth, infection evident before or after staining, very painful ulcers, and cases involving pets with specific anatomical challenges like entropion.? Consider referring your case or scheduling a virtual consultation with an ophthalmologist if you suspect you are treating a SCCED with a patient <6 years old or if your patient is a brachycephalic.? Do not perform a grid keratotomy on a cat.? Consideration of CTA debridement and/or diamond burr for cats is recommended only under specialty direction.

Conclusion

Diagnosis and resolution of SCCEDs requires a comprehensive ophthalmic exam and willingness to select and perform mechanical therapies effectively.? Clear client communication regarding the healing process, at home care, potential for repeat procedure(s), and warning signs to look out for will go a long way in helping you to manage client expectations and avoid serious complications.? With the right approach, including timely referral to specialists when necessary, most pets can achieve a full recovery.? Professional consultation and referral can make a significant difference in the outcome for these often-challenging cases.