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Ophthalmic Surgical Instruments
TOPICAL REVIEW
Ophthalmic Surgical Instruments Gia Klauss, DVM, DACVO With proper training and diligent practice, many orbital, extraocular, and corneo-conjunctival surgeries can be successfully performed by the general practitioner. Specialized surgical instrumentation is necessary to achieve optimal results. This article reviews the essential surgical instruments required for these routine ophthalmic surgeries and provides guidelines for suture selection. Recommendations for handling and care of ophthalmic surgical instruments, including cleaning, sterilization, and storage, are provided. © 2008 Elsevier Inc. All rights reserved. Keywords: veterinary medicine, ophthalmology, ophthalmologic surgical instruments, microsurgical instrumentation, suture, cautery, instrument sterilization
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eneral practitioners are frequently presented with an ophthalmic patient requiring surgical intervention. The general practitioner with advanced surgical training, the requisite ophthalmic surgical instrumentation, and a source of magnification can successfully perform many ophthalmic surgeries of the orbit, eyelids, and ocular surface. Knowledge of ophthalmic anatomy, training in ophthalmic microsurgical technique, and diligent practice of learned techniques on cadaver specimens are necessary for the practitioner to become proficient in ophthalmic surgery. While general surgical instruments can be used for many surgical procedures of the orbit and eyelids, specialized ophthalmic surgical instruments will be of great benefit in orbital and eyelid procedures and are prerequisite to success with corneo-conjunctival surgeries. Standard ophthalmic surgical instruments, such as an eyelid speculum, chalazion forceps, or enucleation scissors, are designed to accomplish specific tasks during the surgical procedure. Minimal training is necessary to use these instruments for their intended purpose. Microsurgical instruments are extremely delicate and expensive instruments that are specifically designed for corneal, conjunctival, and intraocular use. Proper use of these instruments requires advanced training in microsurgical technique. The individual is encouraged to attend continuing education programs with surgical wet labs and to practice surgical technique on cadaver eyes to gain proficiency. Purchasing these instruments represents a significant financial investment, but well-designed instruments forged of high-quality stainless steel or titanium will last many years if handled carefully and serviced routinely by an instrument craftsman. Microsurgical instruments have a shortened length (less than 150 mm) designed for comfortable use within the surUniversity of Minnesota, College of Veterinary Medicine, St. Paul, MN. Address reprint requests to: Gia Klauss, DVM, DACVO, University of Minnesota, College of Veterinary Medicine, 1352 Boyd Avenue, St. Paul, MN 55108. E-mail: [email protected]. © 2008 Elsevier Inc. All rights reserved. 1527-3369/06/0604-0171\.00/0 doi:10.1053/j.ctsap.2007.12.002
gical field, which is limited by the working distance of an operating microscope.1 A brushed satin finish will limit glare from light reflection within the operating field. They are intended to be held as a pencil in the hand, and the instrument tips may be angled to afford better visibility of the tips when held in working position (Fig. 1A).2 Delicate manipulations require fine-motor control, which is executed with the fingertips. Therefore, the surgeon should be seated with forearms and hands supported because fine-motor movements are not possible when the large muscle groups of the upper arms are engaged.3 The surface of an instrument’s finger grip is commonly knurled or serrated to provide a firm grasping platform. The location of the finger grip indicates appropriate placement of the fingers for handling the instrument. The shape of the grasping surface is dictated by the intended purpose of the instrument.4 For example, a forceps that is meant to grasp and stabilize tissue will have a flat, gripping platform (Fig. 1B). An instrument requiring versatility of movement will have a rounded or six-sided handle, which allows the instrument to be rotated by the fingertips about its long axis. An example is the microsurgical needle holder, which is used to pass a small needle along a tight arc through corneal tissue (Fig. 1C).
Magnification Magnification greatly increases the proficiency of the surgeon and allows more precise dissection, suture placement, and wound apposition. A source of magnification can be beneficial for many blepharoplastic procedures and is required for surgeries of the cornea and conjunctiva. Binocular magnifier loupes are an inexpensive source of magnification and commonly provide fixed magnification (generally from ⫻1.75 to ⫻2.5) with a short working distance (20.5 to 51 cm) (Fig. 2).5 Customized surgical telescopes provide increased magnification (up to ⫻4.5) with a wider field of view and can be tailored to the individual’s interpupillary distance and refractive error (Fig. 3). External light sources are required for
3
4
Figure 1. Ophthalmic microsurgical instruments are specially designed for specific tasks. (A) An instrument, such as the Colibri corneal forceps, may have an angled tip to allow visualization of the tissue when the instrument is held in the working position. (B) Conjunctival fixation forceps have a flat handle to provide firm grasp for fixation of the globe. (C) The Barraquer needle driver has a rounded handle that allows the instrument to be rolled between the fingertips to rotate the instrument along its long axis. illumination of the surgical field with magnifier loupes and surgical telescopes. An operating microscope affords the surgeon a wide field of view, variable magnification (generally from ⫻3 to ⫻20), greater working distance (125 to 500 mm), and an integral source of illumination.5 Operating microscopes are available in stationary table- or ceiling-mounted units, or as mobile free-standing units.
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Figure 3. Surgical telescopes can be customized for magnification, working distance, interpupillary distance, and correction of the user’s refractive error (Designs for Vision, Inc., Ronkonkoma, NY). tropion, eyelid laceration repair, aberrant cilia removal, and surgeries of the third eyelid, such as replacement of prolapsed gland of the third eyelid (Table 1). The corneo-conjunctival pack is designed for conjunctival flaps and corneal laceration repair (Table 2). Extraocular procedures are more frequently performed in general practice, and thus, the extraocular pack will experience heavier use. The creation of a dedicated corneo-conjunctival pack, which contains the majority of the microsurgical instruments used in ophthalmic surgeries, prevents these delicate instruments from subjection to unnecessary resterilization with the more frequently used instruments of the extraocular pack.
Eyelid Specula Surgical Instruments Individual packs designed for extraocular and corneo-conjunctival use should be created. The extraocular pack should contain instruments for routine orbital and blepharoplastic procedures such as enucleation, correction of entropion/ec-
Globe exposure is facilitated by use of a self-retaining eyelid speculum (Fig. 4). These are designed to widen the palpebral
Table 1. Extraocular instrument pack
Figure 2. Binocular magnifier loupes provide ⫻1.75 to ⫻2.5 magnification and can be used over eyeglasses (Donegan Optical Co., Lenexa, KS).
Towel clamps Mosquito forceps Bulb syringe and 19 g. cannula Stainless steel bowl Eyelid speculum Chalazion forceps Chalazion curette Lid plate Jameson caliper Cilia forceps Bishop-Harmon forceps Adson forceps Curved Metzenbaum scissors Enucleation scissors Stevens tenotomy scissors Mayo scissors Bard-Parker scalpel handle Derf needle holder
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Volume 23, Number 1, February 2008
Table 2. Corneo-conjunctival instrument pack Towel clamps Mosquito forceps Bulb syringe and cannula Stainless steel bowl Eyelid speculum Castroviejo calipers Iris spatula Bishop-Harmon forceps Conjunctival fixation forceps Colibri corneal forceps Tying forceps Stevens tenotomy scissors Wescott tenotomy scissors Locking Castroviejo needle holders Non-locking Barraquer needle holders
fissure without placing pressure on the globe, which must be avoided in cases where the corneal integrity is weakened or the globe is perforated.6 Two types of eyelid specula are available in various sizes. Wire lid specula are inexpensive, light, and quite versatile (Fig. 4A). A pediatric-sized wire lid speculum is appropriate for globe exposure in cats and small dogs. Sturdier metal eyelid specula of the Castroviejo, Williams, or Guyton-Park types can be used in larger dogs and horses (Fig. 4B). When inserted into the palpebral fissure, the hinge joints are placed temporally with both types of eyelid specula.
Lid Plate Surgical incisions created in the eyelids, as for entropion surgery or wedge-resection of eyelid tumors, are greatly facili-
Figure 4. Eyelid specula. (A) Wire eyelid speculum; (B) Castroviejo eyelid speculum.
Figure 5. Jaeger lid plate. tated with the aid of a rigid lid plate (Fig. 5). Unsupported eyelid tissue will shift under the pressure of an advancing scalpel blade, resulting in a jagged incision.4 With a firm surface to create tautness of the eyelid tissue and to provide counterpressure to the scalpel blade, a smooth incision line can be created. The lid plate is inserted into the conjunctival fornix for use and is available in stainless steel or rigid plastic models.
Forceps A chalazion forceps is available in various sizes and is most commonly used for surgical removal of eyelid tumors, cryoepilation of distichiasis, and en-bloc resection of ectopic cilia (Fig. 6). This forceps serves the dual purposes of stabilizing eyelid tissue and providing temporary hemostasis. The Bishop-Harmon forceps has right-angled 1 ⫻ 2 teeth and is used for manipulation of eyelid and conjunctiva (Fig. 7). Fine and delicate models are available. Fine tips measure 0.5 mm across the tips and are appropriately sized for grasping of eyelid tissue. The delicate tips are 0.3 mm and should be reserved for conjunctival use. Conjunctival fixation forceps are mouse-toothed forceps used to fixate the globe (Fig. 8). The 1 ⫻ 2 teeth are angled, or splayed, and grasp tissue in advance of the forceps during closure, engaging Tenon’s capsule and the deep episcleral and scleral tissue.4 When closed, the points form a trident or anchor for point fixation of the globe. Colibri corneal forceps are very fine forceps with rightangled 1 ⫻ 2 teeth and an angled shaft for grasping cornea (Fig. 9). These teeth are extremely delicate and susceptible to damage with careless use. These are available with or without a short tying platform behind the teeth for tying the fine sutures (7-0 to 10-0) used for corneal suturing. Smooth-tipped forceps are used for tying suture and cilia removal. Tying forceps have flat platforms for tying sutures
Figure 6. Chalazion clamp.
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Figure 7. Bishop-Harmon forceps. Interdigitating 1 ⫻ 2 teeth are right-angled (inset). 7-0 and finer (Fig. 10). Straight and curved tying platforms are available. Cilia forceps are used to epilate cilia and vary in tip design from the broad, rectangular tip of the Storz cilia forceps (Fig. 11A) to the narrow angled tip of the Barraquer cilia forceps (Fig. 11B).
Scissors Ophthalmic scissors are available with blunt, sharp, or semirounded tips and are used for cutting and dissection of conjunctiva and eyelid. Blunt-tipped scissors are most appropriate for conjunctival dissection from the underlying Tenon’s capsule during conjunctival grafting. When the blades are closed, the tips can be safely introduced into the subconjunctival and episcleral tissues for blunt dissection.4 When sharp tips are advanced into these tissues, they act as point cutting edges and may perforate, or “button-hole,” the conjunctiva during dissection. Stevens tenotomy scissors are used for dissection of conjunctival and eyelid tissue and are the most commonly utilized scissors in the ophthalmic instrument pack. They are available with straight or curved blades, sharp or blunt tips, and ring or ribbon-style handles (Fig. 12A). These can be used for cutting of suture finer than 5-0, but larger caliber suture will dull these blades and operating scissors should be used instead. Wescott tenotomy scissors are microsurgical instruments with spring-loaded handles and are utilized for conjunctival dissection to harvest conjunctival flaps (Fig. 12B). These are
Figure 8. Conjunctival fixation forceps. Interdigitating 1 ⫻ 2 teeth are angled (inset). When closed, the forceps teeth form a trident or anchor for point fixation of the globe.
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Figure 9. Colibri corneal forceps have interdigitating 1 ⫻ 2 right-angled teeth and are available with or without a flat tying platform behind the teeth. available in delicate, fine, and heavy-duty blades. The delicate blades could be used for keratectomy of diseased corneal tissue before conjunctival grafting. The highly curved blades of enucleation scissors facilitate transection of the optic nerve during enucleation (Fig. 12C). The semi-rounded tips are closed and inserted behind the globe. Once the optic nerve is identified, the scissors tips are opened to straddle the optic nerve and then closed to transect it.
Needle Holders Standard ophthalmic needle holders, such as the Derf needle holder, are used for 4-0 to 5-0 suture (Fig. 13). Derf needle holders should not be used with larger gauge suture as the larger needles will damage the instrument tips. These needle drivers have smaller jaws, and the serrated grasping surface will not flatten or damage the finer needles of 5-0 suture. Carbide platforms at the tips are more expensive but prevent wear and damage to the instrument caused by the hard steel of the needle. Microsurgical ophthalmic needle holders are available with nonlocking or locking spring-loaded handles (Fig. 14A and B). Both types can be used for suturing conjunctiva and eyelid. Locking needle holders are designed to lock and unlock smoothly with minimal movement of the tips, but they should not be used for corneal suturing because subtle tip movement is unavoidable during disengagement of the locking mechanism. These instruments are available with straight or curved tips and come in heavy-duty, fine, and delicate sizes. The heavy-duty size is appropriate for 6-0 suture, and
Figure 10. Tying forceps are available with straight or curved tips.
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Volume 23, Number 1, February 2008
Figure 11. Cilia forceps. (A) Storz cilia forceps. (B) Barraquer cilia forceps.
the fine and delicate sizes are best suited to 7-0 and finer suture. If the jaws splay at the tips when grasping the needle, then the needle is too large for the instrument.4
Figure 13. Derf needle holder with carbide tip platforms.
Blade Handles
Jameson or Castroviejo calipers are necessary for accurate measurement of tissues during blepharoplastic and corneoconjunctival surgeries (Fig. 16A and B). These instruments permit measurement of tissues in 1-mm increments up to 20 mm (Castroviejo) or 80 mm (Jameson) in length.
The Beaver blade handle is used for disposable Beaver blades and has a rounded handle with knurled griping surface (Fig. 15). The Beaver blade and handle are used for incision of the cornea and for keratectomy of malacic corneal tissue in preparation for conjunctival grafting procedures. The Bard–Parker handle fitted with a no. 15 blade is appropriate for incisions of the eyelid and third eyelid.
Calipers
Cannulas Irrigation cannulas are available in a variety of gauges and are used for tissue irrigation and for intraocular injection of viscoelastic material to manipulate the iris and reform the anterior chamber during corneal laceration repair. These are typically used in conjunction with silicone bulb syringes; however, 5- to 10-mL plastic syringes are reasonable and readily available substitutes. Nasolacrimal cannulas are intended for cannulation of the nasolacrimal punctae and have a malleable metal tip that can be deformed for ease of use. An intravenous catheter (20 to 24 g, with stylet removed) is an acceptable alternative for nasolacrimal cannulation in small animals.
Chalazion Curette Chalazion curettes are used in the surgical treatment of chalazia and are also useful for removal of lipogranulomatous material in surgical debulking of Meibomian gland tumors.
Figure 12. Ophthalmic scissors. (A) Stevens tenotomy scissors with straight blades and blunt tips. (B) Wescott tenotomy scissors with curved, fine blades, and blunt tips. (C) Enucleation scissors have very curved blades to transect the optic nerve.
Figure 14. Microsurgical needle holders. (A) Barraquer nonlocking needle holder with delicate, curved tips. (B) Castroviejo locking needle holder with heavy duty, straight tips.
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Figure 15. Beaver blade handle. Figure 17. Meyerhoefer chalazion curette. The Meyerhoefer chalazion curette has a cup-shaped curette available in varying sizes (1.75 to 3 mm diameter) (Fig. 17).
Dermal Biopsy Punch A 2- to 3-mm diameter dermal biopsy punch can be used for transconjunctival excision of ectopic cilia.7 The biopsy punch is applied to the conjunctival surface to remove a partial thickness section of eyelid tissue, which includes the entire hair follicle of the ectopic cilia.
wire loop that can be gently crimped with hemostats to create a fine point for precise delivery of heat. With repeated use and resterilization, the thermal output intensity of the disposable unit wanes. Thermokeratoplasty is a delicate procedure used for treatment of spontaneous chronic corneal epithelial defects. Referral to a veterinary ophthalmologist for this procedure should be considered as imprecise application of heat can result in deep corneal burns.9
Sponges Sterile cotton-tipped applicators are used as surgical swabs and for hemostasis during extraocular procedures. For intraocular procedures, the cotton-tipped applicators should be avoided as loose fibers may enter the anterior chamber and incite inflammation. Cellulose sponges should be used for corneal and intraocular procedures and are commonly available as wedge-shaped spears (Xomed Surgical Products, Jacksonville, FL).
Pen Cautery Electrocautery can be useful for hemostasis during blepharoplastic procedures and for thermokeratoplasty, or corneal diathermy, for treatment of bullous keratopathy.8 A handheld, disposable, battery-operated electrocautery unit has a
Figure 16. Calipers. (A) Castroviejo calipers. (B) Jameson calipers.
Suture Material For suturing eyelid skin, 4-0 to 5-0 suture is appropriately sized. Silk has been considered the gold standard for suturing of eyelid skin because of its excellent handling properties, knot security, and soft pliable suture ends that are unlikely to traumatize the cornea with inadvertent contact. However, tissue reactivity is high; the braided filaments can wick bacteria to result in infection, and suture granulomas can develop.10 Nonabsorbable monofilament suture, such as nylon or polypropylene, is less likely to cause suture reactions or to act as a wick for bacterial contamination, but care must be taken with knot placement to ensure that that the stiff suture ends do not rub on the cornea. If difficulty with suture removal is anticipated, absorbable braided or monofilament suture can be used for closure of eyelid skin incisions. The absorbable braided suture polyglactin 910 has the advantages of good handling properties, knot security, and softer suture ends, which are less traumatic with corneal contact than more rigid monofilament suture. Stainless steel surgical staples can be used for everting eyelid tacking for temporary correction of entropion. For corneal suturing of conjunctival flaps or corneal laceration repair, 6-0 to 8-0 suture swaged onto an eyeless needle should be selected. Spatula-type needles are best for suturing corneal tissue, but reverse cutting needles are an acceptable alternative.4,11 Absorbable braided or monofilament suture (polyglactin 910 and polyglycolic acid) or nonabsorbable monofilament suture (nylon) may be used in cornea. Absorbable suture results in slightly increased tissue reactivity and vascular response, but suture removal is typically not necessary.12 Nonabsorbable suture elicits minimal suture reaction; however, suture removal is necessary and typically requires sedation or anesthesia. For the general surgeon performing corneal and conjunctival surgeries, 6-0 and 7-0 are the most practical suture sizes, and surgical loupes should provide sufficient magnification. Suture material finer than 7-0 is dif-
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Volume 23, Number 1, February 2008 ficult to see without the magnification afforded by an operating microscope.
Cleaning, Storage, Sterilization, and Maintenance of Surgical Instruments Great diligence and care must be taken with the cleaning, storage, and maintenance of expensive ophthalmic surgical instrumentation to increase the life expectancy of these instruments. The careless surgeon or nurse will experience diminished returns on the costly investment that has been made in the ophthalmic instrument pack if handling protocols are not properly followed. Immediately after surgery, instruments should be soaked in distilled water to soften dried blood and debris and then cleaned with a soft-bristled brush or instrument wipe and rinsed with distilled water. Instruments should be disassembled or opened fully at hinges to ensure complete cleaning of all surfaces and crevices. To prevent damage and dulling of delicate tips and cutting surface, instruments should not come in contact with each other. Instruments should then undergo a final cleaning using a neutral pH instrument cleanser and distilled water in an ultrasonic cleaner. To remove detergents and residue, the instruments are rinsed in distilled water. Tap water should not be used because the minerals present can stain and corrode an instrument’s metal surface. Instruments with moveable parts should then be soaked in an instrument lubricant following the manufacturer’s instructions, and lubricated instruments should be allowed to dry without rinsing. All instruments should dry completely, and compressed air can be used to dry those instruments with lumens, such as cannulas. Delicate instruments should be stored in specifically designed surgical packs which keep the instruments separated. Alternatively, a simple metal tray can be used with surgical drapes or gauze sponges strategically placed to prevent contact between instruments. To increase the longevity of expensive microsurgical instrumentation, tip covers should be used to protect the fine tips of forceps and scissors. Tip covers are commercially available but can also be created from sections of variously sized silicone tubing. The extremely delicate teeth of corneal forceps are easily damaged unless great care is taken with this particularly expensive instrument. Ethylene oxide gas sterilization is ideal for sterilization of ophthalmic surgical packs, but cost and accessibility of this sterilization method is often prohibitive. Autoclaving is the most commonly available method of sterilization and is appropriate for most ophthalmic surgical instruments. Over time, however, the high temperatures used in autoclaving can damage or corrode the most delicate instruments. Flash autoclaving should be avoided when possible as the higher temperatures used are detrimental to the fine points and cutting surfaces of microsurgical instruments and will take a toll on instrument longevity.
Inspection of all instruments should be performed routinely using magnification with head loupes or magnifying glass. Instruments are examined for burrs on cutting surfaces of blades, misaligned or damaged teeth of forceps, or loosened screws at scissors hinges. With early identification of defects, instruments can often be repaired for less than the cost of replacement. The manufacturers of high-quality instruments will often provide servicing of heavily used or damaged items, including sharpening of frequently used scissors, realignment of instruments with mechanical parts, and repair of damaged forceps. The author thanks Dr. Kathryn Diehl for review of this manuscript.
References 1. Gelatt KN: Surgical instrumentation, in Gelatt KN, Gelatt JP (eds): Small Animal Ophthalmic Surgery: Practical Techniques for the Veterinarian. Oxford, Butterworth–Heinemann, 2001, pp 1-16 2. Troutman RC: Instruments, in Troutman RC (ed): Microsurgery of the Anterior Segment of the Eye: Introduction and Basic Techniques, vol 1. St. Louis, MO, CV Mosby, 1974, pp 37-86 3. Troutman RC: Handling the instruments, in Troutman RC (ed): Microsurgery of the Anterior Segment of the Eye: Introduction and Basic Techniques, vol 1. St. Louis, MO, CV Mosby, 1974, pp 87-104 4. Eisner G. Tissue tactics, in Eisner G (ed): Eye Surgery: An Introduction to Operative Technique (ed 2). Berlin, Springer-Verlag, 1990, pp 38-118 5. Gelatt KN: The operating room, in Gelatt KN, Gelatt JP (eds): Small Animal Ophthalmic Surgery: Practical Techniques for the Veterinarian. Oxford, Butterworth–Heinemann, 2001, pp 17-33 6. Eisner G: Preparation of the operating field, in Eisner G (ed): Eye Surgery: An Introduction to Operative Technique (ed 2). Berlin, Springer-Verlag, 1990, pp 119-132 7. D’Anna N, Sapienza JS, Guandalini A, et al: Use of a dermal biopsy punch for removal of ectopic cilia in dogs: 19 cases. Vet Ophthalmol 10:65-67, 2007 8. Murphy CJ, Burling T, Hollingsworth S: Thermokeratoplasty for the treatment of chronic bullous keratopathy in the dog. Trans Am Coll Vet Ophthalmol 24:21, 1993 9. Bentley E, Murphy CJ: Thermal cautery of the cornea for treatment of spontaneous chronic corneal epithelial defects in dogs and horses. J Am Vet Med Assoc 224:250-253, 2004 10. Martin CL: Principles of ophthalmic surgery, in Martin CL (ed): Ophthalmic Disease in Veterinary Medicine. London, Manson Publishing Ltd., 2005, pp 105-112 11. Troutman RC: Needles and sutures, in Troutman RC (ed): Microsurgery of the Anterior Segment of the Eye: Introduction and Basic Techniques, vol 1. St. Louis, MO, CV Mosby, 1974, pp 105-124 12. Van Ee RT, Nasisse MP, Helman G, et al: Effects of nylon and polyglactin 910 suture material on perilimbal corneal wound healing in the dog. Vet Surg 15:435, 1986
Ophthalmic Surgical Instruments Gia Klauss, DVM, DACVO With proper training and diligent practice, many orbital, extraocular, and corneo-conjunctival surgeries can be successfully performed by the general practitioner. Specialized surgical instrumentation is necessary to achieve optimal results. This article reviews the essential surgical instruments required for these routine ophthalmic surgeries and provides guidelines for suture selection. Recommendations for handling and care of ophthalmic surgical instruments, including cleaning, sterilization, and storage, are provided. © 2008 Elsevier Inc. All rights reserved. Keywords: veterinary medicine, ophthalmology, ophthalmologic surgical instruments, microsurgical instrumentation, suture, cautery, instrument sterilization
G
eneral practitioners are frequently presented with an ophthalmic patient requiring surgical intervention. The general practitioner with advanced surgical training, the requisite ophthalmic surgical instrumentation, and a source of magnification can successfully perform many ophthalmic surgeries of the orbit, eyelids, and ocular surface. Knowledge of ophthalmic anatomy, training in ophthalmic microsurgical technique, and diligent practice of learned techniques on cadaver specimens are necessary for the practitioner to become proficient in ophthalmic surgery. While general surgical instruments can be used for many surgical procedures of the orbit and eyelids, specialized ophthalmic surgical instruments will be of great benefit in orbital and eyelid procedures and are prerequisite to success with corneo-conjunctival surgeries. Standard ophthalmic surgical instruments, such as an eyelid speculum, chalazion forceps, or enucleation scissors, are designed to accomplish specific tasks during the surgical procedure. Minimal training is necessary to use these instruments for their intended purpose. Microsurgical instruments are extremely delicate and expensive instruments that are specifically designed for corneal, conjunctival, and intraocular use. Proper use of these instruments requires advanced training in microsurgical technique. The individual is encouraged to attend continuing education programs with surgical wet labs and to practice surgical technique on cadaver eyes to gain proficiency. Purchasing these instruments represents a significant financial investment, but well-designed instruments forged of high-quality stainless steel or titanium will last many years if handled carefully and serviced routinely by an instrument craftsman. Microsurgical instruments have a shortened length (less than 150 mm) designed for comfortable use within the surUniversity of Minnesota, College of Veterinary Medicine, St. Paul, MN. Address reprint requests to: Gia Klauss, DVM, DACVO, University of Minnesota, College of Veterinary Medicine, 1352 Boyd Avenue, St. Paul, MN 55108. E-mail: [email protected]. © 2008 Elsevier Inc. All rights reserved. 1527-3369/06/0604-0171\.00/0 doi:10.1053/j.ctsap.2007.12.002
gical field, which is limited by the working distance of an operating microscope.1 A brushed satin finish will limit glare from light reflection within the operating field. They are intended to be held as a pencil in the hand, and the instrument tips may be angled to afford better visibility of the tips when held in working position (Fig. 1A).2 Delicate manipulations require fine-motor control, which is executed with the fingertips. Therefore, the surgeon should be seated with forearms and hands supported because fine-motor movements are not possible when the large muscle groups of the upper arms are engaged.3 The surface of an instrument’s finger grip is commonly knurled or serrated to provide a firm grasping platform. The location of the finger grip indicates appropriate placement of the fingers for handling the instrument. The shape of the grasping surface is dictated by the intended purpose of the instrument.4 For example, a forceps that is meant to grasp and stabilize tissue will have a flat, gripping platform (Fig. 1B). An instrument requiring versatility of movement will have a rounded or six-sided handle, which allows the instrument to be rotated by the fingertips about its long axis. An example is the microsurgical needle holder, which is used to pass a small needle along a tight arc through corneal tissue (Fig. 1C).
Magnification Magnification greatly increases the proficiency of the surgeon and allows more precise dissection, suture placement, and wound apposition. A source of magnification can be beneficial for many blepharoplastic procedures and is required for surgeries of the cornea and conjunctiva. Binocular magnifier loupes are an inexpensive source of magnification and commonly provide fixed magnification (generally from ⫻1.75 to ⫻2.5) with a short working distance (20.5 to 51 cm) (Fig. 2).5 Customized surgical telescopes provide increased magnification (up to ⫻4.5) with a wider field of view and can be tailored to the individual’s interpupillary distance and refractive error (Fig. 3). External light sources are required for
3
4
Figure 1. Ophthalmic microsurgical instruments are specially designed for specific tasks. (A) An instrument, such as the Colibri corneal forceps, may have an angled tip to allow visualization of the tissue when the instrument is held in the working position. (B) Conjunctival fixation forceps have a flat handle to provide firm grasp for fixation of the globe. (C) The Barraquer needle driver has a rounded handle that allows the instrument to be rolled between the fingertips to rotate the instrument along its long axis. illumination of the surgical field with magnifier loupes and surgical telescopes. An operating microscope affords the surgeon a wide field of view, variable magnification (generally from ⫻3 to ⫻20), greater working distance (125 to 500 mm), and an integral source of illumination.5 Operating microscopes are available in stationary table- or ceiling-mounted units, or as mobile free-standing units.
Topics in Companion Animal Medicine
Figure 3. Surgical telescopes can be customized for magnification, working distance, interpupillary distance, and correction of the user’s refractive error (Designs for Vision, Inc., Ronkonkoma, NY). tropion, eyelid laceration repair, aberrant cilia removal, and surgeries of the third eyelid, such as replacement of prolapsed gland of the third eyelid (Table 1). The corneo-conjunctival pack is designed for conjunctival flaps and corneal laceration repair (Table 2). Extraocular procedures are more frequently performed in general practice, and thus, the extraocular pack will experience heavier use. The creation of a dedicated corneo-conjunctival pack, which contains the majority of the microsurgical instruments used in ophthalmic surgeries, prevents these delicate instruments from subjection to unnecessary resterilization with the more frequently used instruments of the extraocular pack.
Eyelid Specula Surgical Instruments Individual packs designed for extraocular and corneo-conjunctival use should be created. The extraocular pack should contain instruments for routine orbital and blepharoplastic procedures such as enucleation, correction of entropion/ec-
Globe exposure is facilitated by use of a self-retaining eyelid speculum (Fig. 4). These are designed to widen the palpebral
Table 1. Extraocular instrument pack
Figure 2. Binocular magnifier loupes provide ⫻1.75 to ⫻2.5 magnification and can be used over eyeglasses (Donegan Optical Co., Lenexa, KS).
Towel clamps Mosquito forceps Bulb syringe and 19 g. cannula Stainless steel bowl Eyelid speculum Chalazion forceps Chalazion curette Lid plate Jameson caliper Cilia forceps Bishop-Harmon forceps Adson forceps Curved Metzenbaum scissors Enucleation scissors Stevens tenotomy scissors Mayo scissors Bard-Parker scalpel handle Derf needle holder
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Volume 23, Number 1, February 2008
Table 2. Corneo-conjunctival instrument pack Towel clamps Mosquito forceps Bulb syringe and cannula Stainless steel bowl Eyelid speculum Castroviejo calipers Iris spatula Bishop-Harmon forceps Conjunctival fixation forceps Colibri corneal forceps Tying forceps Stevens tenotomy scissors Wescott tenotomy scissors Locking Castroviejo needle holders Non-locking Barraquer needle holders
fissure without placing pressure on the globe, which must be avoided in cases where the corneal integrity is weakened or the globe is perforated.6 Two types of eyelid specula are available in various sizes. Wire lid specula are inexpensive, light, and quite versatile (Fig. 4A). A pediatric-sized wire lid speculum is appropriate for globe exposure in cats and small dogs. Sturdier metal eyelid specula of the Castroviejo, Williams, or Guyton-Park types can be used in larger dogs and horses (Fig. 4B). When inserted into the palpebral fissure, the hinge joints are placed temporally with both types of eyelid specula.
Lid Plate Surgical incisions created in the eyelids, as for entropion surgery or wedge-resection of eyelid tumors, are greatly facili-
Figure 4. Eyelid specula. (A) Wire eyelid speculum; (B) Castroviejo eyelid speculum.
Figure 5. Jaeger lid plate. tated with the aid of a rigid lid plate (Fig. 5). Unsupported eyelid tissue will shift under the pressure of an advancing scalpel blade, resulting in a jagged incision.4 With a firm surface to create tautness of the eyelid tissue and to provide counterpressure to the scalpel blade, a smooth incision line can be created. The lid plate is inserted into the conjunctival fornix for use and is available in stainless steel or rigid plastic models.
Forceps A chalazion forceps is available in various sizes and is most commonly used for surgical removal of eyelid tumors, cryoepilation of distichiasis, and en-bloc resection of ectopic cilia (Fig. 6). This forceps serves the dual purposes of stabilizing eyelid tissue and providing temporary hemostasis. The Bishop-Harmon forceps has right-angled 1 ⫻ 2 teeth and is used for manipulation of eyelid and conjunctiva (Fig. 7). Fine and delicate models are available. Fine tips measure 0.5 mm across the tips and are appropriately sized for grasping of eyelid tissue. The delicate tips are 0.3 mm and should be reserved for conjunctival use. Conjunctival fixation forceps are mouse-toothed forceps used to fixate the globe (Fig. 8). The 1 ⫻ 2 teeth are angled, or splayed, and grasp tissue in advance of the forceps during closure, engaging Tenon’s capsule and the deep episcleral and scleral tissue.4 When closed, the points form a trident or anchor for point fixation of the globe. Colibri corneal forceps are very fine forceps with rightangled 1 ⫻ 2 teeth and an angled shaft for grasping cornea (Fig. 9). These teeth are extremely delicate and susceptible to damage with careless use. These are available with or without a short tying platform behind the teeth for tying the fine sutures (7-0 to 10-0) used for corneal suturing. Smooth-tipped forceps are used for tying suture and cilia removal. Tying forceps have flat platforms for tying sutures
Figure 6. Chalazion clamp.
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Figure 7. Bishop-Harmon forceps. Interdigitating 1 ⫻ 2 teeth are right-angled (inset). 7-0 and finer (Fig. 10). Straight and curved tying platforms are available. Cilia forceps are used to epilate cilia and vary in tip design from the broad, rectangular tip of the Storz cilia forceps (Fig. 11A) to the narrow angled tip of the Barraquer cilia forceps (Fig. 11B).
Scissors Ophthalmic scissors are available with blunt, sharp, or semirounded tips and are used for cutting and dissection of conjunctiva and eyelid. Blunt-tipped scissors are most appropriate for conjunctival dissection from the underlying Tenon’s capsule during conjunctival grafting. When the blades are closed, the tips can be safely introduced into the subconjunctival and episcleral tissues for blunt dissection.4 When sharp tips are advanced into these tissues, they act as point cutting edges and may perforate, or “button-hole,” the conjunctiva during dissection. Stevens tenotomy scissors are used for dissection of conjunctival and eyelid tissue and are the most commonly utilized scissors in the ophthalmic instrument pack. They are available with straight or curved blades, sharp or blunt tips, and ring or ribbon-style handles (Fig. 12A). These can be used for cutting of suture finer than 5-0, but larger caliber suture will dull these blades and operating scissors should be used instead. Wescott tenotomy scissors are microsurgical instruments with spring-loaded handles and are utilized for conjunctival dissection to harvest conjunctival flaps (Fig. 12B). These are
Figure 8. Conjunctival fixation forceps. Interdigitating 1 ⫻ 2 teeth are angled (inset). When closed, the forceps teeth form a trident or anchor for point fixation of the globe.
Topics in Companion Animal Medicine
Figure 9. Colibri corneal forceps have interdigitating 1 ⫻ 2 right-angled teeth and are available with or without a flat tying platform behind the teeth. available in delicate, fine, and heavy-duty blades. The delicate blades could be used for keratectomy of diseased corneal tissue before conjunctival grafting. The highly curved blades of enucleation scissors facilitate transection of the optic nerve during enucleation (Fig. 12C). The semi-rounded tips are closed and inserted behind the globe. Once the optic nerve is identified, the scissors tips are opened to straddle the optic nerve and then closed to transect it.
Needle Holders Standard ophthalmic needle holders, such as the Derf needle holder, are used for 4-0 to 5-0 suture (Fig. 13). Derf needle holders should not be used with larger gauge suture as the larger needles will damage the instrument tips. These needle drivers have smaller jaws, and the serrated grasping surface will not flatten or damage the finer needles of 5-0 suture. Carbide platforms at the tips are more expensive but prevent wear and damage to the instrument caused by the hard steel of the needle. Microsurgical ophthalmic needle holders are available with nonlocking or locking spring-loaded handles (Fig. 14A and B). Both types can be used for suturing conjunctiva and eyelid. Locking needle holders are designed to lock and unlock smoothly with minimal movement of the tips, but they should not be used for corneal suturing because subtle tip movement is unavoidable during disengagement of the locking mechanism. These instruments are available with straight or curved tips and come in heavy-duty, fine, and delicate sizes. The heavy-duty size is appropriate for 6-0 suture, and
Figure 10. Tying forceps are available with straight or curved tips.
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Volume 23, Number 1, February 2008
Figure 11. Cilia forceps. (A) Storz cilia forceps. (B) Barraquer cilia forceps.
the fine and delicate sizes are best suited to 7-0 and finer suture. If the jaws splay at the tips when grasping the needle, then the needle is too large for the instrument.4
Figure 13. Derf needle holder with carbide tip platforms.
Blade Handles
Jameson or Castroviejo calipers are necessary for accurate measurement of tissues during blepharoplastic and corneoconjunctival surgeries (Fig. 16A and B). These instruments permit measurement of tissues in 1-mm increments up to 20 mm (Castroviejo) or 80 mm (Jameson) in length.
The Beaver blade handle is used for disposable Beaver blades and has a rounded handle with knurled griping surface (Fig. 15). The Beaver blade and handle are used for incision of the cornea and for keratectomy of malacic corneal tissue in preparation for conjunctival grafting procedures. The Bard–Parker handle fitted with a no. 15 blade is appropriate for incisions of the eyelid and third eyelid.
Calipers
Cannulas Irrigation cannulas are available in a variety of gauges and are used for tissue irrigation and for intraocular injection of viscoelastic material to manipulate the iris and reform the anterior chamber during corneal laceration repair. These are typically used in conjunction with silicone bulb syringes; however, 5- to 10-mL plastic syringes are reasonable and readily available substitutes. Nasolacrimal cannulas are intended for cannulation of the nasolacrimal punctae and have a malleable metal tip that can be deformed for ease of use. An intravenous catheter (20 to 24 g, with stylet removed) is an acceptable alternative for nasolacrimal cannulation in small animals.
Chalazion Curette Chalazion curettes are used in the surgical treatment of chalazia and are also useful for removal of lipogranulomatous material in surgical debulking of Meibomian gland tumors.
Figure 12. Ophthalmic scissors. (A) Stevens tenotomy scissors with straight blades and blunt tips. (B) Wescott tenotomy scissors with curved, fine blades, and blunt tips. (C) Enucleation scissors have very curved blades to transect the optic nerve.
Figure 14. Microsurgical needle holders. (A) Barraquer nonlocking needle holder with delicate, curved tips. (B) Castroviejo locking needle holder with heavy duty, straight tips.
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Topics in Companion Animal Medicine
Figure 15. Beaver blade handle. Figure 17. Meyerhoefer chalazion curette. The Meyerhoefer chalazion curette has a cup-shaped curette available in varying sizes (1.75 to 3 mm diameter) (Fig. 17).
Dermal Biopsy Punch A 2- to 3-mm diameter dermal biopsy punch can be used for transconjunctival excision of ectopic cilia.7 The biopsy punch is applied to the conjunctival surface to remove a partial thickness section of eyelid tissue, which includes the entire hair follicle of the ectopic cilia.
wire loop that can be gently crimped with hemostats to create a fine point for precise delivery of heat. With repeated use and resterilization, the thermal output intensity of the disposable unit wanes. Thermokeratoplasty is a delicate procedure used for treatment of spontaneous chronic corneal epithelial defects. Referral to a veterinary ophthalmologist for this procedure should be considered as imprecise application of heat can result in deep corneal burns.9
Sponges Sterile cotton-tipped applicators are used as surgical swabs and for hemostasis during extraocular procedures. For intraocular procedures, the cotton-tipped applicators should be avoided as loose fibers may enter the anterior chamber and incite inflammation. Cellulose sponges should be used for corneal and intraocular procedures and are commonly available as wedge-shaped spears (Xomed Surgical Products, Jacksonville, FL).
Pen Cautery Electrocautery can be useful for hemostasis during blepharoplastic procedures and for thermokeratoplasty, or corneal diathermy, for treatment of bullous keratopathy.8 A handheld, disposable, battery-operated electrocautery unit has a
Figure 16. Calipers. (A) Castroviejo calipers. (B) Jameson calipers.
Suture Material For suturing eyelid skin, 4-0 to 5-0 suture is appropriately sized. Silk has been considered the gold standard for suturing of eyelid skin because of its excellent handling properties, knot security, and soft pliable suture ends that are unlikely to traumatize the cornea with inadvertent contact. However, tissue reactivity is high; the braided filaments can wick bacteria to result in infection, and suture granulomas can develop.10 Nonabsorbable monofilament suture, such as nylon or polypropylene, is less likely to cause suture reactions or to act as a wick for bacterial contamination, but care must be taken with knot placement to ensure that that the stiff suture ends do not rub on the cornea. If difficulty with suture removal is anticipated, absorbable braided or monofilament suture can be used for closure of eyelid skin incisions. The absorbable braided suture polyglactin 910 has the advantages of good handling properties, knot security, and softer suture ends, which are less traumatic with corneal contact than more rigid monofilament suture. Stainless steel surgical staples can be used for everting eyelid tacking for temporary correction of entropion. For corneal suturing of conjunctival flaps or corneal laceration repair, 6-0 to 8-0 suture swaged onto an eyeless needle should be selected. Spatula-type needles are best for suturing corneal tissue, but reverse cutting needles are an acceptable alternative.4,11 Absorbable braided or monofilament suture (polyglactin 910 and polyglycolic acid) or nonabsorbable monofilament suture (nylon) may be used in cornea. Absorbable suture results in slightly increased tissue reactivity and vascular response, but suture removal is typically not necessary.12 Nonabsorbable suture elicits minimal suture reaction; however, suture removal is necessary and typically requires sedation or anesthesia. For the general surgeon performing corneal and conjunctival surgeries, 6-0 and 7-0 are the most practical suture sizes, and surgical loupes should provide sufficient magnification. Suture material finer than 7-0 is dif-
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Volume 23, Number 1, February 2008 ficult to see without the magnification afforded by an operating microscope.
Cleaning, Storage, Sterilization, and Maintenance of Surgical Instruments Great diligence and care must be taken with the cleaning, storage, and maintenance of expensive ophthalmic surgical instrumentation to increase the life expectancy of these instruments. The careless surgeon or nurse will experience diminished returns on the costly investment that has been made in the ophthalmic instrument pack if handling protocols are not properly followed. Immediately after surgery, instruments should be soaked in distilled water to soften dried blood and debris and then cleaned with a soft-bristled brush or instrument wipe and rinsed with distilled water. Instruments should be disassembled or opened fully at hinges to ensure complete cleaning of all surfaces and crevices. To prevent damage and dulling of delicate tips and cutting surface, instruments should not come in contact with each other. Instruments should then undergo a final cleaning using a neutral pH instrument cleanser and distilled water in an ultrasonic cleaner. To remove detergents and residue, the instruments are rinsed in distilled water. Tap water should not be used because the minerals present can stain and corrode an instrument’s metal surface. Instruments with moveable parts should then be soaked in an instrument lubricant following the manufacturer’s instructions, and lubricated instruments should be allowed to dry without rinsing. All instruments should dry completely, and compressed air can be used to dry those instruments with lumens, such as cannulas. Delicate instruments should be stored in specifically designed surgical packs which keep the instruments separated. Alternatively, a simple metal tray can be used with surgical drapes or gauze sponges strategically placed to prevent contact between instruments. To increase the longevity of expensive microsurgical instrumentation, tip covers should be used to protect the fine tips of forceps and scissors. Tip covers are commercially available but can also be created from sections of variously sized silicone tubing. The extremely delicate teeth of corneal forceps are easily damaged unless great care is taken with this particularly expensive instrument. Ethylene oxide gas sterilization is ideal for sterilization of ophthalmic surgical packs, but cost and accessibility of this sterilization method is often prohibitive. Autoclaving is the most commonly available method of sterilization and is appropriate for most ophthalmic surgical instruments. Over time, however, the high temperatures used in autoclaving can damage or corrode the most delicate instruments. Flash autoclaving should be avoided when possible as the higher temperatures used are detrimental to the fine points and cutting surfaces of microsurgical instruments and will take a toll on instrument longevity.
Inspection of all instruments should be performed routinely using magnification with head loupes or magnifying glass. Instruments are examined for burrs on cutting surfaces of blades, misaligned or damaged teeth of forceps, or loosened screws at scissors hinges. With early identification of defects, instruments can often be repaired for less than the cost of replacement. The manufacturers of high-quality instruments will often provide servicing of heavily used or damaged items, including sharpening of frequently used scissors, realignment of instruments with mechanical parts, and repair of damaged forceps. The author thanks Dr. Kathryn Diehl for review of this manuscript.
References 1. Gelatt KN: Surgical instrumentation, in Gelatt KN, Gelatt JP (eds): Small Animal Ophthalmic Surgery: Practical Techniques for the Veterinarian. Oxford, Butterworth–Heinemann, 2001, pp 1-16 2. Troutman RC: Instruments, in Troutman RC (ed): Microsurgery of the Anterior Segment of the Eye: Introduction and Basic Techniques, vol 1. St. Louis, MO, CV Mosby, 1974, pp 37-86 3. Troutman RC: Handling the instruments, in Troutman RC (ed): Microsurgery of the Anterior Segment of the Eye: Introduction and Basic Techniques, vol 1. St. Louis, MO, CV Mosby, 1974, pp 87-104 4. Eisner G. Tissue tactics, in Eisner G (ed): Eye Surgery: An Introduction to Operative Technique (ed 2). Berlin, Springer-Verlag, 1990, pp 38-118 5. Gelatt KN: The operating room, in Gelatt KN, Gelatt JP (eds): Small Animal Ophthalmic Surgery: Practical Techniques for the Veterinarian. Oxford, Butterworth–Heinemann, 2001, pp 17-33 6. Eisner G: Preparation of the operating field, in Eisner G (ed): Eye Surgery: An Introduction to Operative Technique (ed 2). Berlin, Springer-Verlag, 1990, pp 119-132 7. D’Anna N, Sapienza JS, Guandalini A, et al: Use of a dermal biopsy punch for removal of ectopic cilia in dogs: 19 cases. Vet Ophthalmol 10:65-67, 2007 8. Murphy CJ, Burling T, Hollingsworth S: Thermokeratoplasty for the treatment of chronic bullous keratopathy in the dog. Trans Am Coll Vet Ophthalmol 24:21, 1993 9. Bentley E, Murphy CJ: Thermal cautery of the cornea for treatment of spontaneous chronic corneal epithelial defects in dogs and horses. J Am Vet Med Assoc 224:250-253, 2004 10. Martin CL: Principles of ophthalmic surgery, in Martin CL (ed): Ophthalmic Disease in Veterinary Medicine. London, Manson Publishing Ltd., 2005, pp 105-112 11. Troutman RC: Needles and sutures, in Troutman RC (ed): Microsurgery of the Anterior Segment of the Eye: Introduction and Basic Techniques, vol 1. St. Louis, MO, CV Mosby, 1974, pp 105-124 12. Van Ee RT, Nasisse MP, Helman G, et al: Effects of nylon and polyglactin 910 suture material on perilimbal corneal wound healing in the dog. Vet Surg 15:435, 1986