Easing the Pressure

The advances in surgical glaucoma technology have got doctors thinking about the possibility of premium lens implantation in a glaucoma patient – but the question is: why and when? 

As in many areas of ophthalmology, there has also been an increased emphasis on improving quality of life and patient satisfaction in the glaucoma patient. With the introduction of microinvasive glaucoma surgery (MIGS) technology, we are now better able to reach that goal. Personally, I’m a big advocate of early intervention. If one of my patients has mild or moderate glaucoma, is on topical meds or has IOPs not at target, I will offer some type of MIGS procedure. The new glaucoma surgeries have allowed us to reduce the drop burden for our glaucoma patients, improve compliance, and, due to the high safety profiles, intervene earlier in the disease process. Another key characteristic of these MIGS procedures is the improved predictability of post-operative refractive outcomes compared with traditional glaucoma surgeries (such as trabeculectomy and tube surgeries). To me, it is no longer acceptable to “just bring the IOP down,” but rather, we should strive to attain target IOP, while maintaining or even improving quality of life. Therefore, why shouldn’t our glaucoma patients deserve premium options during cataract surgery?

Due to the unpredictable post-operative refractive outcomes of traditional glaucoma surgery, and the fact that we would wait to perform surgery until the patient had more advanced glaucoma, many of these patients were not good candidates for premium IOLs. Now that we are intervening earlier in the disease course (healthier fields and ONH), getting more and more patients off drops (decreasing the chance of ocular surface disease and noncompliance), premium IOL technology is often part of the IOL discussion. For me, toric IOLs are a  great way to start incorporating premium lenses. There is really no downside to reducing post-op uncorrected astigmatism. On the whole, if a patient has corneal astigmatism – any more than 0.75 diopters – I feel it is worth addressing with a lens; studies have demonstrated improved contrast sensitivity in low light conditions when correcting this level of astigmatism. Even if a patient has advanced glaucoma, I use a monofocal toric lens or accommodating toric lens wherever possible. Sure, the patient may need additional surgery or even a standard trabeculectomy in the future, which could lead to wearing glasses or a change in prescription, but I always explain that to the patient ahead of time.

Historically, one would shy away from multifocal lenses in glaucoma patients because of the potential loss of contrast sensitivity inherent to these lenses, given that, as mentioned earlier, loss of contrast is one of the earliest manifestations of glaucomatous optic neuropathy. The newer lower add multifocal and EDOF lenses claim to offer less loss of contrast sensitivity than the previous higher add multifocal lenses, which has allowed us to re-evaluate the use of multifocal lenses, especially in the mild glaucoma patient. Another choice for me, the Crystalens accommodating IOL, has been a safe lens to implant in glaucoma patients as it is an aspheric monofocal optic that does not negatively affect quality of the image. I’m currently running my own study, looking into the mean deviation of glaucoma patients’ visual field pre and post cataract surgery. By using ray tracing (iTrace, Tracey Technologies), we are also comparing HOA and MTF between Crystalens and various multifocal IOLs. Data should be available by ASCRS 2019.

I’m aware not everyone feels the way I do. As glaucoma surgeons, we are often primarily concerned with getting pressures down, and we sometimes don’t think it is worth using a premium lens, such as toric lens – but I think that paradigm is starting to change. 

We have already seen a huge shift here in the US, especially now, when there are so many options available. Don’t dismiss the need for maximizing refractive outcomes in glaucoma patients – they deserve the same uncorrected quality of vision as everybody else.