ABSTRACT: Ophthalmic surgery requires a range of instruments, ranging from standard surgical kit to microsurgical instruments used with an operating microscope. How much ophthalmic equipment your practice has will depend on the interests and experience of your surgeons, and whether you have a specialist ophthalmic surgeon. This article is aimed at general practice nurses wishing to identify and take care of the eye kit'. There is little more annoying (and expensive) than getting the kit out to find damaged instruments.

Types of procedure

Ophthalmic procedures can be divided into three broad groups. These are:

•   eyelid surgeries, such as entropion correction

•   conjunctiva and corneal surgeries, for example, conjunctival grafts and repair of corneal lacerations

•   intraocular surgery, which includes removal of a cataract or a luxated lens.

Vitreo-retinal surgery is the preserve of highly trained specialists, and requires microsurgical equipment and an imaging system – these are not available, as a rule, in general practice.1

Most ophthalmic procedures require magnification, usually in the form of a head-worn loupe with a light source.

 

Types of instrument

Ophthalmic surgery has the same requirements of its instruments as general surgery – instruments to cut, grasp and manipulate both tissue and sutures as efficiently and with as little trauma as possible.

Some instruments are used in many procedures, while others are used only for specific cases. What follows is an overview of the more commonly found ophthalmic instruments. There are many variations on these, as a quick search of the internet or perusal of instrument catalogues will demonstrate.2’3

Scissors

Along with conventional Metzenbaum scissors used in orbital and extensive lid surgery, a further selection of scissors is used for the different tissues within the eye (Figure 1).

Figure 1: Selection of ophthalmic scissors. A. Steven's Tenotomy Scissors; B. Strabismus Scissors; C. Pooley's Conjunctival Scissors D. Iris Scissors; E. Castroviejo's Corneal Scissors

Stevens tenotomy scissors (Figure 1A) and Strabismus scissors (Figure 1B) are usually used in the conjunctiva. Strabismus scissors resemble miniature Metzenbaum scissors with blunt tips. Tenotomy scissors are sharper tipped. Both are available straight and curved. These can also be used to cut ophthalmic sutures.

Pooley’s conjunctival scissors are another example (Figure 1C). Of this type of instrument, iris scissors (Figure 1D) are also often used in the conjunctiva – but rarely the iris.

As the cornea of the dog and cat is quite tough to cut, a stab incision is made and extended with scissors – for example, castroviejo corneal scissors (Figure 1E).1 These are of the ribbon handle pattern rather than the ring handle pattern, more common in larger instruments. They are available with the blades pointing left or right and with varying lengths of blade, in addition to the standard pair pictured.

Specific care requirements of ophthalmic scissors include protection of the tips at all times. It is all too easy to damage corneal scissors in particular.

Tissue forceps

There is a very large selection of ophthalmic forceps – many have been developed for specific tasks and tissues. As you would expect, the main difference is in the tips, but the one thing they all have in common is fragility!  

Fixation forceps, such as Barraquer’s (Figure 2A) or Graefe (Figure 2B) are used to hold the globe in place because, when the patient is under anaesthesia, it tends to rotate. They can also be used to hold the conjunctiva or nictans.1

Figure 2: Selection of ophthalmic forceps. A. Barraquer's Fixation Forceps; B. Grafe Fixation Forceps; C. St Martin’s Corneal Forceps D. Castroviejo's Corneal Forceps; E. Colibri (Barraquer's) Forceps; F. Graefe Iris Forceps G. Arruga Capsule Forceps; H. Castroviejo's capsule Forceps

Corneal forceps typically have fine rat teeth to aid grip. They are all very delicate and prone to damage, so must be protected. St Martin’s corneal forceps (Figure 2C) are straight, as are Castroviejo’s (Figure 2D). Colibri (Barraquer's) forceps (Figure 2E) are probably the most well-known, with their off-set shape to improve visualisation.

Iris forceps are available with or without teeth, for example the graefe iris forceps (Figure 2F).

Capsule forceps are used during cataract procedures, to manipulate the lens capsule. Arruga capsule forceps (Figure 2G) are standard-action forceps while the Castroviejo’s (Figure 2H) have a cross-action similar to a towel clip.

Cilia forceps are used to remove individual cilia when dealing with distichiasis. The classic epilation forceps have a flat gripping surface with an . angled end (Figure 3A). An alternative to this is Bennet’s cilia forceps which have small circular tips (Figure 3B).

Figure 3: Cilia and lid forceps. A. Epilation Forceps; B. Bennett's Cilia Forceps; C. Distichiasis Clamp; D. Chalazion Forceps

The distichiasis clamp (Figure 3C) is used to hold the everted eyelid firmly in place to give access to the edge of the lid during distichiasis procedures. This is often the type of instrument that ends up in the back of the cupboard as no one can remember what it is for, and the vet who wanted it has left!

Chalazion forceps (Figure 3D) consist of a flat plate which goes under the lid and an upper ring which is positioned around a chalazion (type of lid cyst) or small lid tumour and tightened down to stabilise it for removal.

Needleholders

Ophthalmic needleholders come in many shapes and sizes (Figure 4).

Figure 4: Needleholders.

A. Castroviejo's Needleholders with Catch; B. Castroviejo&#39
;s Needleholders without Catch; C. Ryder [Micro) Needleholder; D. Derf Needleholder; E. Robert's Tying Forceps

They have to cope with very small and fine needles, but can be one of the most abused ophthalmic instruments. The classic ophthalmic needleholder is the Castroviejo, available with or without a built-in catch to hold the jaw shut on the needle (Figures 4A & 4B). This needleholder has an odd squeeze-release mechanism which surgeons who use them regularly get used to, but occasional surgeons often struggle with.3 This needleholder is only suitable for the very fine needles found on 6/0 and finer suture materials.

Ryder (Micro) needleholders are a more conventionally shaped locking needleholders which can cope with most fine ophthalmic sutures (Figure 4C). The jaws are very narrow, so they should still only be used with very small needles – using a standard needle in these is tempting, but will often result in twisting the jaws out of alignment.

The Derf needleholder (Figure 4D) is a small needleholder with slightly heavier jaws than the Ryder. This is a tougher customer and is useful, particularly for lid surgery. It is also more resistant to vet abuse!

Along with needleholders, tying forceps are required, to grasp very fine ophthalmic sutures. The commonest of these is the Robert s tying forceps (Figure 4E). Tying forceps have a flat platform behind the tip which is used to grip the suture material without damaging it. Again these are fragile and easily twisted and damaged.

Speculae

The classic Barraquer wire speculum (Figure 5A) is probably the most well known. This is simple, inexpensive and available in two sizes – its spring-loaded shape holds it in place. The Lister speculum is larger, longer and heavier (Figure 5B). This has a locking facility, which the Barraquer does not.

Figure 5: Speculae, scalpels and spatula.

A. Barraquer Speculum; B. Lister Speculum; C. Jaeger Speculum; D. Beaver blade handle E. Kimura spatula

The Jaeger speculum is used in lid surgery, such as wedge resections, and is also available in an insulated version for use with electrocautery units (Figure 5C). It slides under the lid to stabilise it and protect the globe and provide a firm cutting surface.

Scalpels

The common Bard-Parker handle (Swann-Morton No 3) can be used with a suitable blade for some lid procedures, but is too bulky for most ophthalmic cases. The more usual blade holder is the Beaver handle (Figure 5D). This takes specific blades (Swann-Morton Fine series) which are held in place by a screw mechanism. Take great care when unscrewing the blade – both to avoid injury and not to lose the small blade retainer.

Specialist surgeons may use a diamond knife. This requires very careful handling and special cleaning. Follow the manufacturers instructions at all times and do not clean in an ultrasonic instrument cleaner as this damages the diamond section.1'4

Spatula/vectis

The Kimura spatula (Figure 5E) and Snellens vectis are examples of instruments used to help extrude a luxated lens during removal. They are used to apply pressure to the globe rather than having to ‘fish’ the lens out, so need to be smooth and free of damage to avoid unnecessary irritation of the globe.3

Care and maintenance

As with all instruments, the care cycle is: Clean/Inspect/Lubricate/Package/Sterilise /Store/Use.4-5 

If instruments are used infrequently, then sterilisation is best left until required, to avoid corrosion caused by damp storage.3 Ophthalmic instruments should be cleaned very carefully. Rinse immediately with water after use, to remove saline and blood, and use a neutral pH detergent designed for instrument cleaning. If you are hand washing, clean each item individually, handling with care.

Ultrasonic cleaners are the most effective way to clean these fine instruments. When loading the ultrasonic machine, place each item individually into the cleaner and position to avoid jostling the instruments together. If you have any titanium instruments, put them through on a separate cycle to the stainless steel ones as it is generally not advisable to mix metal types in an ultrasonic cleaner.5

Do not put diamond knives in the ultrasonic – they have their own cleaning block and storage tray.5 Always follow the manufacturer’s instructions for these.

After cleaning, each instrument must be inspected for damage. A simple magnification visor will make this possible (Figure 6).

Figure 6: Equipment required for care of ophthalmic instruments – magnification visor, a selection of protective tips and a case insert

Check:

•   that the toothed tips of tissue forceps meet correctly

•   the tips of pointed scissors for damage

•   needleholders are aligned correctly (the gripping surfaces meet and are not offset) and check surfaces for wear and damage

•   the tying platform and tips of tying forceps for damage

•   the blades of speculae are smooth and free of damage.

Lubricate joints, as with conventional instruments – spray oils are useful (Instol, Veterinary Instrumentation): tip protectors should be used as far as possible, particularly on pointed scissors and fine forceps.

It is recommended that fine instruments be stored and autoclaved in cases with fingered silicone mats to hold them in place. Instruments which are used less frequently should be packed individually, and opened only if required to avoid unnecessary risk of damage during reprocessing.

Cases should be large enough to contain the instruments without crowding, but do not allow too much additional space as this provides the potential for them to ‘rattle around’ and become damaged. There are many of these cases on the market, both from specialists and general instrument suppliers.

Finally…

Consider giving responsibility for the # ophthalmic instruments to one person. These are not usually ‘high-volume’ procedures, so this should not be too difficult but will allow a little TLC and continuity of care.

Replacement costs for damaged ophthalmic instruments can be very high. Looking after these carefiilly will increase instrument life. The saddest thing I have heard is that one of the reasons a surgeon uses disposable ophthalmic instruments is that he cannot trust staff to look after better ones! 

Author

Linda Capewell VN

Linda qualified in 1988 after 10 years in practice with the PDSA in Sheffield, as one of the first group of the charity's VNs. She spent a total of 26 years with the PDSA, and then in 2004 she left and joined Veterinary Instrumentation as veterinary technical support manager. She now deals with a wide range of queries every day.

To cite this article use either

DOI: 10.1111/j.2045-0648.2012.00240.x or Veterinary Nursing Journal Vol 27 pp 413-416

References

1.   KIRK. N. GELATT. Chapter 1 – Surgical instrumentation. Veterinary Ophthalmic Surgery. W.B. Saunders, Edinburgh, 2011, Pages 1-15. ISBN 9780702034299, 10.1014/B978-0-7020- 3429-9.00001-8. www.sciencedirect.com/science /article/pi i/B9780702034299000018

2.   Dixey Instruments catalogue.

3.   Veterinary Instrumentation catalogue 2012.

4.   The Katena Instrument Care Booklet – A Guide to Proper Care and Handling of Delicate Surgical Instruments, www.katena.com/htmiy mstrument_care.cfm

5.   John Weiss International website – Instrument Care section, www.iohnweiss.com/instrument-care.

• VOL 27 • November 2012 • Veterinary Nursing Journal