Endodiathermal tautening used for intraoperative floppy iris in EK, PK
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Eyes undergoing keratoplasty are often complex and may have already undergone previous surgery. In these cases, the iris may not be completely normal in shape, tone and/or structure.
An irregular or incomplete iris may be seen, and an iridoplasty may be required in such cases for improving vision, decreasing photopic phenomena, decreasing risk for peripheral anterior synechiae (PAS) formation and/or improving anterior chamber dynamics. A floppy iris may also be seen intraoperatively in some cases, and this can interfere with air dynamics in endothelial keratoplasty (EK). In such situations, one of the authors (SJ) started to use controlled endodiathermy to tauten the iris and remove floppiness. It was also used to flatten the iris and shrink the bunched-up iris stroma seen post-suture iridoplasty.
Source: Soosan Jacob, MS, FRCS, DNB, and Amar Agarwal, MS, FRCS, FRCOphth
Floppy iris
Excess mobility of the iris is seen in some cases intraoperatively, and this may result in instability of the air bubble meant for holding the graft up in EK or for forming the anterior chamber in penetrating keratoplasty. A floppy iris during keratoplasty can cause air to migrate behind the iris and result in pupillary block, anterior bowing of the iris, increased IOP as well as loss of support for an EK graft and consequent graft detachment. It can also result in forward movement of the lens-iris diaphragm and shallowing of the anterior chamber. An excessively shallow anterior chamber can interfere with insertion of instruments or even the graft and result in iris damage, hyphema and difficulty in unscrolling the graft.
In PK, a floppy iris can move forward during the open sky part of surgery, risking lens expulsion and even expulsive hemorrhage. Even after closure with the graft, a floppy iris predisposes to shallowing of the anterior chamber and PAS formation. All these can be avoided by endodiathermal tautening of the mid-peripheral iris stroma.
Bunched-up iris after suture iridoplasty
Iridoplasty may be done using sutures in both PK and EK. In PK, suture iridoplasty is done in an open sky manner, whereas in EK, it may be done using any of the techniques described, such as Siepser knot, McCannel suture or four-throw pupilloplasty. Although suture iridoplasty restores the iris to a more normal shape, it can result in an uneven anterior iris plane at the site of approximation of the iris leaflets and can also result in iris bunching. This results in an uneven anterior chamber and poor air dynamics, especially in endothelial keratoplasties.
In all these situations, the endodiathermy probe can be used to tauten the iris and remove floppiness. Controlled endodiathermy to the iris also helps to flatten the iris and shrink bunched-up iris stroma. This is done by application of controlled diathermy on the mid-periphery at the area of the bunched-up or floppy iris. This helps maintain a stable anterior chamber and avoids iridocorneal touch and PAS. A stable anterior chamber in turn helps improve air dynamics and prevents air from migrating behind the iris.
History
Endodiathermy has been used for many years in ophthalmic surgery. Vitreoretinal surgeons have been using it for various purposes, most commonly for achieving hemostasis but also for creating retinotomies or for marking around retinal tears or holes. However, a vitrectomy setup is not essential to be able to use the endodiathermy probe. It may also be connected via the phaco machine or to a cautery unit through the connecting wires. The endodiathermy probe is available as a 20-, 23-, 25- and 27-gauge instrument. It has a fine tip and produces thermal effect only at the tip.
Past use in anterior segment
Endodiathermy has been used by anterior segment surgeons for making the pupil more circular and centered, for making a rhexis or even for creating a new pupil in patients with occlusio pupillae or fully updrawn pupils. However, our use of endodiathermy for EK is to flatten a floppy iris and thereby avoid excessive mobility and anterior bowing.
Procedure
The anterior chamber is continuously irrigated with balanced salt solution via an anterior chamber maintainer. Endodiathermy is started at low power initially (around 25%), and the tip of the probe is applied against the iris stroma in the mid-periphery. It is then activated and the power slowly increased until the desired effect is obtained. Application is in localized spots to induce tautening of the iris stroma accompanied by flattening and straightening. The endpoint is when the floppiness of the iris is gone or when iris bunching is decreased. Applications are made to the mid-peripheral iris stroma or at the area of bunched-up iris near the pupilloplasty knots. This results in intraoperative flattening of the iris. Applications close to the pupillary border should be avoided to prevent localized pupillary margin contraction or notching. Darker irides have a greater effect than lighter irides. In the long term, depigmentation of the iris stroma may be noted but, even in deeper pigmented eyes, is generally not obvious unless examined with a slit lamp or torch light.
Conclusion
Endodiathermal tautening of a floppy or irregular iris can be achieved, resulting in better air fill, decreased iris mobility, and a wider, more regular and stable anterior chamber, thus helping air dynamics as well as preventing PAS formation in both EK and PK.
- For more information:
- Amar Agarwal, MS, FRCS, FRCOphth, director of Dr. Agarwal’s Eye Hospital and Eye Research Centre, is the author of several books published by SLACK Books, sister company of Healio publisher Ocular Surgery News, including Phaco Nightmares: Conquering Cataract Catastrophes, Bimanual Phaco: Mastering the Phakonit/MICS Technique, Dry Eye: A Practical Guide to Ocular Surface Disorders and Stem Cell Surgery and Presbyopia: A Surgical Textbook. He can be reached at aehl19c@gmail.com; website: www.dragarwal.com.
- Soosan Jacob, MS, FRCS, DNB, of Dr. Agarwal’s Eye Hospital in Chennai, India, can be reached at dr_soosanj@hotmail.com.
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