Instrumentation

The von Hippel trephine demonstrating the key, the headpiece containing the clockwork spring, and attachable trephine blades. (From: Arthur von Hippel, 1841-1916, in Mannis, M.J. and Mannis, A.A., eds. Corneal Transplantation: A History in Profiles, J.P. Wayenborgh, Belgium, 1999) Instruments for enucleation and excision come in a variety of styles and sizes (Figures 7 and 8).  Speculums may be simple spring wire devices, or more complicated ones with lever expanding mechanisms, locks, and solid or open blades.  All accomplish the same basic function.  Most are standard size which fit individuals from small children (2-3 years old) to adults.  For younger children and infants a special smaller "pediatric" lid speculum may be required. Forceps come in three basic types.  Smooth forceps are used for handling thin delicate membranes.  Serrated forceps are used when fixation or a strong, high-friction grasp is required to apply tension to, or tear a flexible membrane (such as conjunctiva or Tenon's).  Toothed forceps are meant to fixate, move, or place tension on less delicate, more dense tissue such as sclera or cornea. Scissors are used to shear various types of tissue.  They are chosen by their size, durability, curvature, and blunt or sharp-pointed tip styles.  Delicate tissue can be cut with small, relatively lightweight scissors.  Blunt tip scissors are usually chosen for conjunctiva to allow them to push layers of tissue apart without perforation or laceration.  A moderate curve allows the circumference of the globe to be followed.  Enucleation scissors require heavy-weight, strongly curved blunt tips to push through the layers of tissue without catching, fit deep in the orbit behind the globe, and cut the optic nerve.  The corneal section scissors are medium in weight with strong, blunt, curved tips to cut the sclera near the limbus without catching on the underlying tissue, or perforating into the vitreous.  Ring end handles are used on larger scissors (ring handle scissors).  Smaller or more delicate varieties have  spring ends which help to open the blades (spring handle scissors). This is especially useful when the scissors are so small that they can only be handled by a person's fingertips. The enucleation spoon is a cup on a handle with a groove cut in it for the optic nerve. Its used to lift the globe out of the orbit and also to protect the posterior globe when cutting the nerve.  A similar looking device, the evisceration spoon is smaller, with sharp edges, and is used exclusively to scrape or curette the inside surface of the posterior globe after removal of the corneo-scleral rim.

Instruments for enucleation (Figure 7)   1. Adult speculum 2. Pediatric speculum 3. Muscle hook 4. Hemostat 5. Enucleation spoon  6. Light duty ring scissors  7.  Toothed tissue forceps (with stop) applicators  8.  Toothed tissue forceps  9.  Serrated tissue forceps 10. Heavy-duty curved enucleation scissors 11. Metal bowl 12. Cotton tipped

Muscle hooks are "L" shaped instruments used to hook under the rectus muscles. Hemostats or clamps are usually serrated-tipped to hold thicker tissue, such as the rectus muscles, when they are used as a handle for the globe. They lock by closing the ring handles together and open by squeezing and separating the ratcheting portion of the handle lock, placing the ring handles in different planes, in a sideways motion.

Instruments for cornea excision (Figure 8) 1.   Ring handle scissors 2.   Hemostat 3.   Blunt-tip spring handle scissors 4.   Fine-toothed tissue forceps 5.   Serrated tissue forceps 6.   Trephine 7.   Pointed tip scalpel blades 8.   Evisceration spoon

Scalpel blades used in eye banking techniques are usually straight, sharp-point tipped, similar to a standard Bard Parker(R)  # 11 blade.  Some prefer to use a curved tip blade similar to a Bard Parker(R) #15 blade, especially for scraping the conjunctiva from the globe.  They dull quickly and are disposable.  Trephines are tubular blades sharpened at one end.  They can be used to mark or partially cut the corneo-scleral rim. Because of their heftier construction and expense they are frequently re-used and may be re-sharpened.

Sterile cage and jar for whole globe transport. An alligator clip is used to secure the nerve and fixate the globe to the cage structure. The gauze at the bottom is moistened with sterile eye wash, saline, or balanced salt solution to provide high humidity in the chamber, hence the name "moist chamber storage".                                                         (Figure 9a) Enucleated globes are stored and shipped in moist chambers using a cage device and alligator clip to fixate the globe (Figure 9a).  Corneal storage and viewing chambers (CSVC's) come in two sizes to fit existing specular microscopes (Figure 9b). As an alternative corneo-scleral rim tissue can be placed in glass vials used for media shipping and storage and viewed in vertical fixation devices with mirrors attached to allow horizontal viewing at the slit lamp (Figure 9c). Terminology of eye banking instruments includes the terms contaminated, external, clean and internal.  External instruments describe those which are used on the conjunctiva and sclera which are kept separate from those used to handle the cornea and perform the excision.  External instruments are considered contaminated due to their contact with the non-sterile external tissue.  Clean and internal instruments are used to handle internal structures of the eye which are considered sterile and non-contaminated.  The major objective of importance is to avoid having the external instruments mix with the internal instruments, thereby avoiding contamination of the donor tissue.

Corneal storage and viewing chambers (CSVC's).  The upper photo shows the overall view.  The lower photograph illustrates the diameter of the chambers as well as the internal structure that supports the corneal-scleral button. The two sizes are to accommodate different specular microscopes.                                                            (Figure 9b) A glass vial (see Figure 12), typically used to supply media in, may also be used as a container for the donor tissue.  Specular microscopy is not able to be performed  in this type of container. Slit lamp evaluation and specular reflection of the endothelium may be performed with the slit lamp viewing mirror as shown.                                                                (Figure 9c) Table of Contents Next Section