IRIS DEFECTS

Cataract surgery in eyes with iris defects can be challenging, but careful preparation as well as recent advances in surgical instruments and iris implants mean outcomes are significantly improving for these patients, Sathish Srinivasan FRCSEd, FRCOphth told the XXXVII UKISCRS Annual Congress in Manchester. Dr Srinivasan, University Hospital Ayr, Ayr, Scotland, gave a comprehensive overview on how to approach cataract surgery in patients with iris defects, with detailed surgical video demonstrations of his work on these patients.

The main causes of iris defects are either congenital, eg, colobomas or ICE syndrome; and acquired, eg, from a trauma, tear, iris melanomas/cysts, iridodialysis or traumatic mydriasis; or iatrogenic – from an iridectomy or collateral iris damage from previous surgery. Dr Srinivasan said these patients can be difficult to operate on and advised taking a practical, comprehensive approach to surgical preparation.

“If you are dealing with patients with iris defects, they need a lot of planning and a practical approach, so prepare,” he stressed.

Proper preparation includes taking a thorough history, understanding fully the nature of the injury or defect, identifying what has been done previously to treat the patient and assessing the current collateral damage to the cornea, sclera and lens. Lens status becomes a very significant issue even if patients do not have a very visually significant cataract, Dr Srinivasan explained.

“When it comes to the lens status it is very important to know if the patient has a clear lens, cataract or is pseudophakic because when it comes to iris suturing this becomes a very important issue because it is very difficult to do intraocular suturing in a phakic eye,” he told the meeting. The size of the iris defect is also very important in relation to iris suturing, as is the availability of tissue, Dr Srinivasan noted, advising that the patient’s eye is fully measured, photographed and all details documented carefully pre-surgery. Discussing the different suturing techniques, Dr Srinivasan mentioned the McCannel Technique, and Siepser Knot, which helps do a sliding knot into the anterior segment.

‘We now also have the new concept of intracameral suturing, where you can suture inside the anterior chamber because of several advancements in microsurgical instrumentation, with 23-gauge instruments now available with micrograspers, microscissors and microforceps, which helps us do all these steps,” he said.

When it comes to selecting the suture material, Dr Srinivasan recommended using a non-reactive suture such as a monofilament polypropylene one in the anterior chamber so as to avoid intraocular inflammation. Regarding needle choice, he said a straight or curved one can be used, and he prefers a CIF-4. When an iris defect is just too large to close there is the option of artificial iris implants. Candidates for artificial iris implants include patients who have sustained trauma or have congenital aniridia.

Dr Srinivasan, who has extensive expertise in this area, explained that these implants are not designed to be placed in the sulcus; they go into the capsular bag. There are now three different brands on the market made by Morcher, Ophtec and HumanOptics.

Depending on the iris defect, it is possible to decide what type of partial aniridia rings to use and customise the implant, he said. If the defect is larger it is possible to use scleral-fixated lenses, which have an artificial iris diaphragm with a customised IOL optic in the centre, Dr Srinivasan added. “The lens of choice goes into the capsular bag and it is very important to note the edge of your capsulorhexis to help guide you putting in the implant,” he noted. These implants are “very fragile” so it is advisable to have a spare one in the operating theatre. Protecting the corneal epithelium is also very important during this surgery, he cautioned.

Dr Srinivasan showed the meeting a number of videos and images of his surgery on these patients to illustrate how to conduct the surgery and avoid pitfalls and to assess the postoperative result. The physical appearance of artificial iris implants postoperatively is very good and looks very natural, especially with customisation to the patient’s own eyes, he reported. Patients are very happy with the surgery, not just because of the cosmetic and visual improvement, but because of the reduction in glare, which can be a serious issue for patients with iris defects.

Speaking to EuroTimes, Dr Srinivasan said artificial iris implant surgery is on the whole not a very difficult procedure, and is becoming increasingly popular. He advised surgeons interested in the procedure to check out the implant companies’ websites, where he said there is a lot of useful literature as well as many surgical videos.

Sathish Srinivasan: Sathish.srinivasan@gmail.com