The world of glaucoma care is rapidly changing, with an explosion of new technologies for microinvasive glaucoma surgery (MIGS). But even before these tiny devices, usually implanted at the time of cataract surgery, began to appear, there was a growing realization among ophthalmologists that cataract surgery itself was a glaucoma procedure.
For at least the past decade, it has been recognized that cataract surgery, on average, lowers IOP in both normotensive and hypertensive eyes.1,2 The IOP-lowering effect of cataract removal and IOL implantation is proportional to the patient’s preoperative IOP; that is, the decrease is greatest in patients with the highest IOPs before surgery.2 In patients with notably elevated preoperative IOP (23 to 31 mm Hg), reductions of a mean 6.5 mm Hg (27%) have been reported, whereas in those with average or low IOP the effect is more modest, in the range of 1 to 2 mm Hg. This effect has been seen to last up to 10 years.2
When any MIGS procedure is done in conjunction with cataract surgery, therefore, the patient, on average, may get the bonus of extra IOP lowering from lens removal.3 There are other benefits of having the lens out sooner rather than later in glaucomatous eyes. For example, in the event that a patient’s glaucoma progresses and a trabeculectomy is needed, it is better to have previously removed the lens rather than risking trabeculectomy failure related to cataract surgery following successful trabeculectomy.
For these and other reasons, I believe that cataract surgery makes subsequent glaucoma management easier. As safe as some MIGS procedures appear to be from published reports, ophthalmologists need to start thinking about performing these surgical glaucoma interventions earlier in the course of the disease rather than later. We have been used to waiting to perform surgery because of the risks involved with penetrating procedures such as trabeculectomy and tube shunt implantation. Now, some MIGS procedures combined with cataract surgery appear to have safety profiles similar to that seen with cataract surgery alone.4
LIVING LONGER WITH GLAUCOMA AFTER CATARACT SURGERY
Another factor in this equation is the aging of the population. Patients are increasingly living into their 90s and beyond, so we are going to have many more older patients with glaucoma who will need our care. With patients living longer and having cataract surgery earlier, the number of post–cataract surgery years will be greater for the average glaucoma patient in the future. Thus the impact of a successful glaucoma surgical procedure performed at the time of cataract surgery can include reduced medication dependence and improved glaucoma care for longer than in prior generations. Assuming that the therapies work, this is a clearly a good approach from a public health perspective.
The average period of post–cataract surgery glaucoma care, which in the past might have been 5 to 10 years, is likely to be 20 or more years for future generations of glaucoma patients. If we can make cataract surgery an inflection point—add a MIGS procedure that will help to decrease the patient’s IOP and/or medicaition dependence for a period of many years after cataract surgery—we will undoubtedly improve glaucoma care.
1. Foroozan R, Levkovitch-Verbin H, Habot-Wilner Z, Burla N. Cataract surgery and intraocular pressure. Ophthalmology. 2008;115:104-108.
2. Poley BJ, Lindstrom RL, Samuelson TW. Long-term effects of phacoemulsification with intraocular lens implantation in normotensive and ocular hypertensive eyes. J Cataract Refract Surg. 2008;34:735-742.
3. Singh K. Things go better with cataract surgery. Ophthalmology. 2014;121(1):1.
4. Samuelson TW, Katz LJ, Wells JM, Duh YJ, Giamporcaro JE; US iStent Study Group. Randomized evaluation of the trabecular micro-bypass stent with phacoemulsification in patients with glaucoma and cataract. Ophthalmology. 2011;118(3):459-467.