, but do not cut the lateral orbital ligament. An eyelid speculum in the eye at the time of the canthotomy will make this easier.
Preparation of the Patient
Chemical restraint and general anesthesia
Medication with antibiotics or steroids prior to surgery
Adnexal surgery
Intraocular surgery
Emergency procedures
Systemic medications
Protect cornea
Clipping
Skin and globe preparation
Principles of Surgery of the Globe
Exposure
Canthotomy
Keeping the eye open
Globe stabilization
Fixation or bridle suture
Forceps stabilization
Instrumentation
Surgical instruments
Suture material
Absorbable
Non-absorbable
Epilators
Choice depends on the examination or procedure.
Examination, minor manipulations, and minor surgery of adnexa can be accomplished with ketamine and a tranquilizer.
Major intraocular surgery or enucleations - inhalation anesthesia is necessary to provide immobilization of the extraocular muscles and adequate anesthesia.
Examination and minor manipulations - topical anesthetic usually is adequate.
General surgery - short procedures can be done with intravenous, fast acting barbiturates; long procedures should be done using inhalation anesthesia.
Examination and minor manipulations - xylazine is excellent and can be combined with topical anesthesia with auriculopalpebral nerve block for minor adnexal surgery.
General surgery - similar to dog.
Local blocks in the bovine species - see article by Elmore for information.
You generally should not do elective surgery on infected or inflamed tissue.
If there is conjunctivitis or blepharitis, it should be controlled with medication before surgery; otherwise, no medication is required before surgery.
Treatment with antibiotics and steroids is required prior to all elective procedures; this type of surgery generally should be limited to specialists or to those who want to do it routinely thus developing and maintaining competence; discussion of intraocular surgery is beyond the scope of these notes.
Antibiotic preparation is not routinely placed in the eye before emergency surgery.
Only needed for intraocular surgery or involved eyelid surgery and parotid duct transposition. Use standard doses of a broad spectrum antibiotic and steroids if you believe they are necessary.
For intraocular surgery, aspirin, flunixin or other anti-inflammatory drug often is used beginning 24 hours prior to surgery to reduce prostaglandin-induced postoperative inflammation. Each specialist, however, may have her or his own regimen.
It may be desirable to place a scleral shell beneath the eyelids prior to clipping - however, this does not mean that you then can be careless or that the eyeball is totally protected - if you are careful, no shell is necessary.
Hair should be removed as gently as possible. You may want to use curved scissors rather than clippers if there is a recent penetrating injury to the globe which is not sealed with fibrin (otherwise, manipulation may result in prolapse of intraocular structures); petroleum jelly on the scissor blades helps collect the hairs as they are cut.
Cleanse with iodine-based surgical scrubs - do not use soap, alcohol or iodine tincture as in general surgery; when doing the scrub and rinse do not use free-flow water or dripping-wet sponges - the proper technique is to wet the sponge (usually cotton or gauze) with water, squeeze out the water until the sponge is just moist, apply some scrub material to it and then use this for scrubbing; this applies to rinsing also - squeeze out the sponge before applying to the skin to remove the scrub material; the conjunctival sac and globe should be rinsed with either sterile saline or mild eye wash (most commercial products are adequate).
Be aware that there is the oculocardiac reflex which may complicate surgery involving the globe (Clutton, et al.). Other references which might be useful to you include: cryosurgery (West and Barrie) and general surgery (Wyman).
Good exposure is necessary, but excessive manipulation or tension to expose the eye can be detrimental. If necessary, a lateral canthotomy may be done. An eyelid speculum of some sort should be used.
Prolapsing or proptosing of the eye is the alternative to canthotomy and eyelid stabilization. It easily is done in cattle and in dogs with large eyelid openings. However, proptosis is not a satisfactory method of exposing and stabilizing the eye in most cases because it 1) reduces blood flow to the anterior segment, 2) increases intraocular pressure, which in turn 3) makes intraocular surgery disastrous. It should be reserved for cattle in the field where good surgical technique is not always convenient.
The entire thickness of the eyelid at the lateral canthus is incised with scissors
Barraquer wire speculum - manufactured by many companies (see section on instruments). This is one of the best specula available. It is effective, simple and inexpensive. The small version is best for dogs and cats; the larger version can be used on larger animals.
The eye tends to rotate downward and medially when the eye is manipulated or the patient is in lighter planes of anesthesia. This necessitates fixing the globe in position if the region to be operated disappears from view.
This should be placed in the sclera 1-2 mm from the limbus at the 12:00 o'clock position.
Use 5-0 or 6-0 non-absorbable suture with a cutting needle to minimize trauma. An open loop can be tied and then attached to skin using a towel clamp. A similar suture can be used at the 6:00 o'clock position if necessary.
Can use Allis tissue forceps on conjunctiva; can also use Graefe fixation forceps or Bishop-Harmon forceps to temporarily hold the globe in the correct position.
Do not use hemostats as they crush tissue.
Most are designed for a specific job, but can be used for several different ones. For delicate surgery, must use the correct instruments or else difficulty and poor results will occur.
The following are those which I believe are the minimum the general practitioner should have in order to do some of the routine ophthalmic surgery not requiring a specialist's expertise:
..; these can be helpful in some forms of entropion surgery. Although you could use tongue depressors or other means of protecting the eye during entropion or similar surgery, these forceps are advantageous for not only protection, but also for hemostasis.. I recommend this type rather than the ones with spring action because you can easily open them even when there is blood or other tissue on the blades.. These are essentially indispensable for handling conjunctiva, pulling out many types of foreign bodies and so forth.. These are particularly useful for 'digging' out corneal foreign bodies. They are considerably cheaper than, although as efficient as, so-called foreign body forceps. for flushing nasolacrimal system. You also can make your own cannulas by filing down the tip of an appropriately sized needle beyond the bevel using a very fine file such as a jeweler's file (it is better not to cut off the sharp tip because you may crush the needle). Round the edges of the new tip with the file, remove any burrs inside the tip using the point of a #11 scalpel blade, and polish the tip using very fine steel wool. The tip must be smooth so that it does not damage the canaliculus or lacrimal sac. These cannulas work best if there is a moderate bend towards the end: slight curve for dogs, about 45 degrees for cats.. A good pair of eyebrow tweezers can satisfactorily substitute for these and are considerably less expensive.Only a few of the most popular ones used by ophthalmic surgeons are listed here. Sizes smaller than 6-0 require special handling and should be reserved for use by specialists.
Dexon® - 7-0 polyglycolic acid with CE-20 cutting needle.
Ethicon® - 6-0 plain collagen with G-1 cutting needle.
Ethicon® - 5-0 chromic catgut with C-3 cutting needle.
Ethicon® - 4-0 Ethibond® with FS-2 cutting needle.
Perma Tweez® - General Medical Company. According to another source dated July 2000, can be ordered through Johnson Smith Company catalog; 914.747.2356.
Inverness One Touch - Stalling Technology, 17-10 Willow Street, Fair Lawn, NJ 07410; 800.631.0860; available through most chain drug stores and some department stores.