PROCEED WITH CAUTION

 Advanced cataract in a patient with Rieger’s anomaly and well-controlled IOP 20 years after a trabeculectomy .Courtesy of Thiemo Rudolph MD, FEBO

A beginner surgeon’s chances of success in their first cases involving eyes with cataract and glaucoma are greatly enhanced through a slow and well-considered approach, said Thiemo Rudolph MD, FEBO, Sahlgrenska University Hospital, Gothenburg, Sweden, at a Young Ophthalmologists Symposium at the 19th ESCRS Winter Meeting in Istanbul. 

“Once you have mastered the basics of a new skill, there are two ways you can go, you can go faster or you can attempt more difficult challenges. Both are perfectly legitimate goals, but doing both things at the same time is something you should try to avoid. This is true in general, but I think it is particularly true when it comes to cataract surgery in glaucoma patients,” Dr Rudolph said. 
The slow approach to cataract surgery in such cases begins early in the patient assessment and treatment planning stages of the procedure. Glaucoma patients require a very detailed preoperative work-up, with many more variables to consider than in a normal cataract patient. The surgeon, together with the patient, must weigh the individual contribution of the two separate pathologies to the patient’s vision loss as well as the risks of the surgery to the optic nerve and future intraocular pressure (IOP) control.

TREATING TWO PATHOLOGIES
In a glaucoma patient with a cataract and poorly controlled IOP, the first important decision is whether to perform the cataract or the glaucoma procedure first, or alternatively, the two combined.
The current consensus supports the performance of the cataract procedure first, Dr Rudolph said. For example, the European Glaucoma Society’s guidelines state that modern phacoemulsification with clear corneal incisions will not reduce the efficacy of subsequent filtration surgery, and that cataract surgery following glaucoma filtration surgery can impair the functionality of the bleb. In addition, combined procedures are generally less effective than trabeculectomy alone in lowering IOP.
When choosing the filtration procedure first, the AGIS study showed that filtration surgery brings with it a 50 per cent risk of cataract within five years. Drainage tube implantation is as cataractogenic as trabeculectomy, but its functionality is less likely to be affected by subsequent cataract surgery.

IOP-LOWERING EFFECT
Dr Rudolph noted that studies have consistently shown that phacoemulsification alone has a small but significant impact on IOP reduction in eyes with open-angle glaucoma. Most of the studies indicate reductions of around 2.0mmHg by one year after surgery. 
The reports have mainly concerned primary open-angle glaucoma, but there is also research suggesting that phacoemulsification has a slightly greater IOP-lowering effect in pseudoexfoliation glaucoma. 
In eyes with angle-closure glaucoma, phacoemulsification should definitely be considered the first treatment option. Randomised trials show that phaco alone has similar results to phacotrabeculectomy, but with significantly fewer complications, he said. 
“In eyes with a narrow angle, dehydrating the vitreous prior to phacoemulsification is essential. Even then, there is an elevated risk of iris prolapse, and for that reason, great care is required when making the main incision. And because you have a more confined space, it is best to keep the phaco tip in the iris plane as much as possible,” Dr Rudolph advised. 
He also recommended that surgeons be thoroughly acquainted with the behaviour of the OVDs they use before proceeding with this type of surgery. He added that in his experience using a somewhat cohesive OVD provides a little bit more space in which to work. In all such cases the surgeon should expect a small pupil, because sometimes a small pupil will only become apparent during surgery.

CASE STUDY
When a patient who has already undergone glaucoma surgery presents with a cataract, a successful outcome is possible when appropriate precautions are taken, Dr Rudolph said. As an illustration, he described and demonstrated with a video clip the case of a woman who presented with cataract nearly 20 years after undergoing a trabeculectomy with a still-functioning bleb and well-controlled IOP in one eye, while the other eye was practically blind due to severe amblyopia.
The patient had Rieger’s anomaly and had undergone a trabeculectomy with a large iridectomy in 1996. Following the glaucoma procedure she had a pressure of 10mmHg with a stable visual field defect. However, in 2014 she began showing the signs and symptoms of cataract.
After receiving carefully considered and thorough information and having some time to think about her options and the risks involved, the patient opted for phacoemulsification and intraocular lens (IOL) implantation. Special measures that Dr Rudolph used during the procedure included iris hooks to stabilise the pupil and the placement of a capsular tension ring for zonular support.
At her most recent follow-up more than three months after the phaco procedure, the patient’s IOP had returned to its preoperative level without local treatment. 
“My take-home message for glaucoma surgeons is simply, don’t be hasty, don’t rush yourself and don’t rush the patient into a decision. If your patient has a basic understanding of what you’re doing and why, you will feel much safer doing the surgery,” Dr Rudolph concluded. 

thiemo.rudolph@gmail.com