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Phaco with IOL implantation could be best approach for glaucoma patients
The natural aging process of the crystalline lens could be a major cause of ocular hypertension and glaucoma, a study suggests.
CHICAGO – Phacoemulsification with IOL implantation is an effective method for lowering pressure in patients with ocular hypertension or glaucoma with IOP of 20 mm Hg and higher, a researcher said.
“Today, [phacoemulsification with IOL implantation] may be the most successful, often used and unrecognized operation for ocular hypertension and glaucoma,” Brooks J. Poley, MD, said at the American Society of Cataract and Refractive Surgery meeting here.
 Brooks J. Poley |
Dr. Poley presented a retrospective study that he and OSN Chief Medical Editor Richard L. Lindstrom, MD, along with OSN Glaucoma Section Editor Thomas W. Samuelson, MD, conducted to examine IOP reductions in 124 glaucomatous eyes.
Patients had visual field or optic nerve loss and/or were using glaucoma drops or had undergone previous trabeculectomy or laser iridotomy. Preoperative IOP measured 5 mm Hg to 29 mm Hg, with eyes stratified into groups according to IOP range, Dr. Poley said. Pressures were measured preoperatively, 1 year postoperatively and at the last chart recording, from 1 to 10 years follow-up, he said.
In a telephone interview with Ocular Surgery News, Dr. Poley said that the study results show that combined procedures are less necessary because lens exchange reduces IOP adequately without filtration surgery. Performing cataract surgery alone appears to produce safe and long-lasting results, he said.
“During the time of my practice, I kept saying, ‘If only we had an operation that was as good for glaucoma as we had for cataract, wouldn’t that be wonderful,’” said Dr. Poley, who is retired. “And I believe the answer is, we do. It’s the same operation.”
Dr. Lindstrom told OSN that the study results support the pressure lowering that he and Dr. Samuelson have seen in their cataract patients for years and demonstrate that combined surgeries could become a technique of the past.
“We almost never, or very rarely, do combined procedures anymore in typical patients with combined cataract-glaucoma, whereas, 10 years ago, if a patient had cataract and glaucoma and was on these two meds, and even in some cases on one med, I would almost routinely do a combined procedure,” he said.
Study findings
Dr. Poley and colleagues found that pressure reductions in 124 glaucomatous eyes were similar to results of a study that they conducted on 588 nonglaucomatous subjects whose IOP was measured after phaco surgery. That study was presented at the ASCRS meeting last year.
In this year’s study, Dr. Poley and colleagues found that the group of eyes with the highest pressure, ranging from 23 mm Hg to 29 mm Hg, had the highest mean reduction (8.4 mm Hg), averaging 16.3 mm Hg at the final measurement. No patient in that group had an elevation in pressure.
 Crystalline growth with age shown in vivo composite picture of a 49-year-old patient on the left and a 24-year-old patient on the right.  Lens exchange in a 74-year-old patient’s eye. In vivo composite image. Before (right) and after (left) phaco and IOL implantation. Images: Strenk LM, Strenk SA. Drs. Strenk wish to acknowledge that their research was supported in part by NEI grants R43EY18518, R43EY15655 and R01EY011529. |
“That’s really quite a key finding because the patients that it’s important that we drop the pressures significantly are the ones that are in the 22 mm Hg to 25 mm Hg or 25 mm Hg to 30 mm Hg range,” Dr. Lindstrom said.
The second highest pressure group had a range of 20 mm Hg to 22 mm Hg, with a reduction of 4.6 mm Hg to 16.3 mm Hg at last measurement. Dr. Poley and colleagues found that 97% of eyes with IOP in the range of 20 mm Hg to 22 mm Hg had reductions at 1 to 10 years, and 3% had pressures that remained the same with no elevations.
The group with the lowest IOP, ranging from 5 mm Hg to 14 mm Hg, had a slight elevation of 1.7 mm Hg to 13.3 mm Hg.
IOP reductions at the final measurement, with an average of 4.5 years follow-up, were the same as at 1 year, the researchers said.
They also found a reduction in glaucoma medication, from a preop mean of 1.3 medications to a postop mean of one medication.
Dr. Lindstrom said numerous researchers have presented similar postulations about the aging lens, but the unique aspect of this study was the results. He said while other studies have looked at all pressures together, resulting in smaller reductions, Dr. Poley stratified the IOPs of patients from Minnesota Eye Consultants and Schulze Eye Surgery according to low and high ranges.
Through this stratification, the effect of cataract surgery on reducing high IOP in patients who typically need the most treatment was more readily evident, Dr. Lindstrom said.
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Aging lens
Age did not appear to affect IOP reductions, with all age groups showing proportional pressure changes, according to the researchers.
The aging lens, however, appeared to affect the glaucomatous process. In the telephone interview, Dr. Poley said the aging lens is not often cited as a possible cause or contributor to ocular hypertension and development of glaucoma, but the anatomy of the process seems to prove otherwise.
Dr. Lindstrom said there are several anatomical changes as the crystalline lens grows with age (Figures 1 and 2). As the lens expands, the eye remains the same size. This process causes the anterior chamber to shallow, often resulting in reduction in the facility of outflow, he said.
There is also a connection between the zonules, ciliary muscle and the trabecular meshwork that could be affected as the lens expands. Dr. Lindstrom said it could be postulated that as the zonules move forward, they pull on the trabecular meshwork, reducing ciliary outflow. When the lens is removed, the eye again returns to its former anatomy, he said.
“To me, putting things back in the natural anatomy that they were at a much younger age, even arguably with the posterior chamber lens in a deeper chamber and a more posterior placement of the plane of the lens than even occurs naturally in a young patient, might be anticipated to increase the facility of outflow,” Dr. Lindstrom said. “Arguably, it works a little bit the same as topical pilocarpine.”
Changing treatment paradigm
Dr. Poley said that these results and other similar studies could completely overhaul the glaucoma treatment paradigm. He predicted that, in the future, physicians might not only view the aging lens as a major cause of ocular hypertension and glaucoma, but also perform phaco on all glaucoma patients, even those with clear lenses.
“I believe the success of this operation will allow doctors to start thinking about treating patients with ocular hypertension or glaucoma with phaco-IOL implantation,” he said.
While performing phaco can significantly reduce IOP in patients with high pressures, Dr. Lindstrom cautioned that patients who have the procedure will most likely still need medications and glaucoma surgery in the future.
He said he would not yet remove the crystalline lens in patients with clear lenses unless they also have a refractive error that they want to correct.
“Now that we know that removal of the natural lens is effective in lowering IOP, then the question arises — when is it indicated,” Dr. Lindstrom said. “I’m at what I would call a two-hit stage in my thinking on this. The patient has two pathologies – for example, cataract and glaucoma or if the patient has a significant refractive error and glaucoma – then that’s, perhaps, a reasonable way to go.”
For more information:
- Richard L. Lindstrom, MD, can be reached at Minnesota Eye Consultants, 9801 DuPont Ave. S, Suite 200, Bloomington, MN 55431; 952-888-5800; fax: 952-567-6182; e-mail: rllindstrom@mneye.com.
- Brooks J. Poley, MD, can be reached at scbrooks@hargray.com.
- Erin L. Boyle is an OSN Staff Writer who covers all aspects of ophthalmology.