Clinical Pearls for the equine eye exam - DVM
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Clinical Pearls for the equine eye exam
Vision and cozmfort best assessed in patient's familiar environment


DVM360 MAGAZINE


Lavage placement There are several useful pearls while placing the lavage. Profound sedation is very helpful, permitting first-time placement. The patient's reaction increases substantially with each additional attempt. The needle is slid under the eyelid guarded by a gloved finger until the orbital rim is palpated. If the patient reacts, a Q-tip or finger may be placed initially, and SPL placement may be resumed when the patient again acclimates. Elevating the eyelid reduces the working space and frequently results in incorrect placement. Ensure that no wrinkles of conjunctiva are entrapped on the stylet point to avoid placement in the middle (moving portion) of the eyelid (Figure 2). The lavage line will not move if it is seated within 2-4 mm of the orbital periosteum and sits safely in the dorsal fornix. Corneal ulceration is a complication if the soft tip is permitted to abrade the epithelium during blinking (Figure 2). When positioned for skin puncture, the needle should be held firmly at the distal end to swiftly traverse the eyelid in one pass. I prefer the skin puncture to be at the mid-point of the dorsal orbital rim, where it closely coincides with the acupuncture point Jing Ming. This site can provide chronic low-grade analgesia, and certain individuals appear more comfortable almost immediately, beyond that anticipated with sedation alone. Ensure that no knots are present in the coil of lavage line before threading the needle. Alternatively, the lavage may be placed through the inferior eyelid, or even retrograde within the nasolacrimal duct, although both of these methods require that medication must move against the flow of gravity. Attention to aseptic technique minimizes the risk of eyelid abscessation. Oral antibiotics may resolve a small reaction at the site rapidly, but profound blepharitis indicates the SPL should be repositioned. Minor fibrosis almost always occurs, and granulation is common at the site of the SPL egress through the skin but rapidly resolves after removal. Careful maintenance allows extended treatment periods of four weeks to eight weeks. Sparing amounts of vaseline or other viscous barrier ointment will limit persistent open sores resulting from epiphora and excess medication causing facial wetness and irritation beneath the lower eyelid.

When correctly placed, the flaccid eyelid should not move when the lavage line is pulled. If it does, the cautious action is to reposition the SPL while the stylet is still sterile. A printed area on the tube should be visible adjacent to the eyelid, and allows the client to monitor the lavage position.

Medications are administered analogous to the use of an intravenous catheter. The injection cap is replaced periodically. Syringes with swaged-on small gauge needles (such as insulin syringes) minimize dead space and medication wastage, and extend the life of the injection cap. Dose volume of 0.15-0.2mL is adequate for most patients. I prefer to slowly propel each medication with air and ensure its delivery. An alternative is to sequentially load each medication in the line, allowing the latest medication to propel the oldest. Potential disadvantages are inexact dosing and risk of medication loss. Self-contained pumps may be added to the system to provide continuous irrigation of the ocular surface with ophthalmic solutions. Ophthalmic suspensions and viscous products, such as natamycin (antifungal) and serum should be followed with a solution to prevent obstruction of the line. The major disadvantage of pumps is that individuals most in need of such continuous care typically need more than one medication. A three-way stopcock may be added to allow additional intermittent therapies as desired. The additional expense of the system is rapidly recuperated with more accurately delivered medication, reduced frustrations, and more rapid recovery. Few clients later regret the placement of an SPL, but many wish the it was present from the beginning of medication.

Mechanical protection Protective facewear is helpful to prevent rubbing of the cornea. Hard-cup hoods are ideal but produce tremendous sweating in hot climates. Additional ventilation holes may be bored to reduce sweating. Fly masks are often sufficient to prevent rubbing, but a determined horse can still do damage while wearing a fly mask. Cross-tying is highly effective for individuals who are accustomed to it, but is not recommended otherwise. Rapid control of uveitis with NSAIDs and atropine substantially reduce the impetus to rub. Stall confinement is recommended, and horses with an SPL should be permitted limited turnout under constant observation. Similarly, commingling with other horses is likely to result in SPL damage.


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Source: DVM360 MAGAZINE,
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