Anterior Segment Cataract Figure 2: Rosenwasser Shovel
into the wound. Given that these devices are inserted completely through the wound, the device protects the tissue from wound-induced tissue compression. The tissue is then advanced or injected into the anterior chamber. Both irrigating (obviating the need for a separate anterior chamber maintainer, e.g. Neusidl Corneal Inserter [see Figure 4]) and non-irrigating injectors are available.
In addition to the above devices, some surgeons simply either ‘push’ the tissue into the eye on a bed of viscoelastic or pull the tissue in, similar to using a glide. To date, there is one technique that has been shown to be superior and the choice of insertion technique is based more on surgeon preference.
The donor cornea is placed on the platform and then introduced into the anterior chamber.
Figure 3: Tan Endoglide AB
Once the tissue is successfully placed into the anterior chamber, the surgeon needs to insure that it is properly oriented (endothelial side down), in proper position (reasonably centered over the pupil), and adheres to the patient’s posterior stroma. This is all much easier to do in a deep and stable chamber. Before any further surgical manipulation, the wound (and any side incisions) needs to be secured. The number of sutures needed to secure the wound(s) varies depending upon the width of the wound, the length of the tunnel, and the wound construction. The wound(s) need to be secured so that the anterior chamber can hold a near-total air bubble without leakage.
A: Introduction of the glide into the wound; B: A second instrument reaching across the anterior chamber to pull the tissue into the eye.
Figure 4: Neusidl Corneal Inserter
The tissue is placed on the platform and then retracted into the irrigating barrel. The tissue is then injected into the anterior chamber.
be a bent needle or cystotome. Glides require a separate anterior chamber maintainer. Reusable glides (e.g. Busin glide) and disposable glides (e.g. Tan Endoglide [see Figure 3]) are available.
Injectors—these devices (similar to a foldable intraocular lens injector) have the donor lenticule inside a protected barrel that is then inserted
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Once the wound is secured, the anterior chamber should be partially reformed with balanced salt solution and then a small amount of air then injected underneath the donor cornea. Both manipulations (fluid and air) are best done with a 30 gauge cannula, which causes less distortion (i.e. leakage) than either 25 or 27 gauge cannulae. Care should be taken to insure that no air is injected in the interface (between the recipient and the donor cornea). Once a small air bubble is in place, the tissue needs to be positioned to its desired location. The donor lenticule can often be moved by gently stroking the surface of the patient’s cornea with a dull instrument (muscle hook or specifically designed ‘rollers’). However, the tissue often has to be directly contacted (using a reverse Sinskey hook or similar) and moved into position. Once the cornea is in the proper position, the anterior chamber needs to be filled with a nearly complete air bubble. Air needs to be injected slowly and in a controlled fashion. A rapid injection will often lead to leakage from the wound or will force air through the pupil behind the iris, and, if unrecognized, can lead to pupillary block and/or appositional angle closure. The eye should be firm, but not hard (we recommend ≥30 mmHg). A dilating drop given at this time will lessen the chance of pupillary block and might release any air that is trapped behind the iris. At this point, some surgeons make small ’venting‘ or ’draining‘ incisions through the host cornea into the donor–host interface to remove any trapped fluid or air. The use of venting incisions is somewhat controversial as there have been isolated reports of epithelial seeding in the interface and interface infectious keratitis.
The air should be left in under direct surgeon observation while the anterior chamber is totally air filled. The amount of time that a full air fill is left varies from surgeon to surgeon, and can be anywhere between 10 and 30 minutes, as it will vary depending on the intraocular pressure of the eye. After the waiting period, a portion of the air is exchanged with balanced salt solution. The amount of air left in the anterior chamber when the patient leaves the operating suite varies greatly
US OPHTHALMIC REVIEW
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