August 2013

 

GLAUCOMA

 

The comprehensive cataract surgeon and glaucoma


by Kerry D. Solomon, MD

   
Dr. Solomon

Dr. Solomon presents at the 2013 ASCRS•ASOA Symposium & Congress.

Source: EyeWorld

With the rapid introduction of advanced technologies and techniques, the role of the comprehensive cataract surgeon continues to expand. Progressive clinical refinements, including small incision surgery and foldable lenses, have ushered in astigmatically neutral incisions. The use of limbal relaxing incisions to treat pre-existing astigmatism and the introduction of multifocal, accommodating, toric, and aspheric IOLs have greatly improved visual outcomes for millions of patients. As new technologies are brought to market, comprehensive cataract surgeons continue to improve quality of life for a broadening range of patients.

Glaucoma is the second leading cause of blindness, affecting more than 60 million people worldwide.1 With approximately 20% of cataract cases having concomitant glaucoma and/or ocular hypertension (OHT),2 it is logical that cataract surgeons are now also treating glaucoma. While severe glaucoma remains the purview of a glaucoma specialist, comprehensive cataract surgeons often take on the task of managing mild to moderate cases.

Severe glaucoma or uncontrolled IOP, requiring the attention of a glaucoma specialist, is often treated with surgeries such as trabeculectomy or shunts. While these are the standard of care in extreme cases, the procedures are fraught with risks and side effects including hypotony and the accompanying blurred vision. To avoid these perils, mild to moderate patients are frequently prescribed ocular hypertensive medications to control glaucoma. This eliminates the risks of surgery, but brings with it a different set of complications. Compliance is a dominant issue with glaucoma eye drop medication. More than 90% of patients do not adhere to their ocular medication dosing regimens, and nearly 50% discontinue taking their medications before six months.3 Non-adherence can result in large fluctuations in IOP, which are associated with a risk of vision loss that is higher than the risk associated with nonintervention.3,4 For those patients who do administer their medications as indicated, long-term, compounded exposure to the preservatives found in many eye drop medications can cause corneal surface damage,5 decreasing the success of subsequent surgical procedures, among other problems. There is a new space being created by novel technologies that will provide the comprehensive ophthalmologist a surgical means to reduce a patient's dependence on glaucoma medications. One such example is the iStent (Glaukos, Laguna Hills, Calif.). The 1-mm long iStent is inserted into Schlemm's canal and facilitates aqueous outflow through the trabecular meshwork. While it may be inserted in a standalone procedure, the iStent is most commonly inserted ab interno through the phaco incision and can be performed under topical anesthesia. Placement of the iStent is a microinvasive and astigmatically neutral procedure that works synergistically with cataract surgery. In clinical studies, 73% of patients who received the iStent remained medication free while sustaining target IOPs of ≤21 mm Hg versus only 50% of those who underwent cataract surgery alone,6 and the mean reduction in IOP was 8.4 mm Hg.7 In addition, one year postoperatively 67% of patients who received the iStent remained medication free.8

The postoperative recovery is virtually identical to cataract surgery alone, with studies showing no additional complications compared to cataract surgery alone.6 The iStent achieves sustained target pressures while significantly reducing or eliminating the drug burden, with virtually no downside. There is no postoperative hypotony, fluctuating vision or shallowing anterior chamber, and the iStent in no way eliminates surgical options for the future, should a patient need further procedures. The continuous expansion of comprehensive cataract surgery can serve the patient, the practice, and the healthcare system. Most patients with glaucoma are prescribed one or more ocular hypotensive medications daily to manage their disease. Significant increases in noncompliance, cumulative side effects, and out-of-pocket costs, as well as decreased quality of life, are strongly correlated with the increasing number of medications patients are prescribed.9 For patients with combined cataract and glaucoma conditions, the iStent can significantly decrease medication use, thereby reducing the overall healthcare costs and time associated with traditional glaucoma management.10 The iStent expands the treatment options that ophthalmologists can offer to their patients with combined cataract and glaucoma to improve clinical outcomes.

References

1. Quigley HA, Broman AT. The number of people with glaucoma worldwide in 2010 and 2020. Br J Ophthalmol. 2006; 90:262-267.

2. Centers for Medicare and Medicaid Services. 2002-2007 Medicare Standard Analytical File. Baltimore, MD: Centers for Medicare and Medicaid Services, US Dept of Health and Human Services; 2007.

3. Nordstrom BL, Friedman DS, Mozaffari E, Quigley HA, Walker AM. Persistence and adherence with topical glaucoma therapy. Am J Ophthalmol. 2005;140:598-606.

4. The AGIS Investigators. The Advanced Glaucoma Intervention Study (AGIS): The relationship between control of intraocular pressure and visual field deterioration. Am J Ophthalmol. 2000;130:429-440.

5. Noecker RJ, Herrygers LA, Anwaruddin R. Corneal and conjunctival changes caused by commonly used glaucoma medications. Cornea. 2004;23:490-496.

6. Samuelson TW. Prospective randomized trial of cataract surgery with iStent implantation and cataract surgery alone in mild-moderate open-angle glaucoma. Paper presented at: American Academy of Ophthalmology Annual Meeting; October 2009; San Francisco, CA.

7. Shingleton B, Tetz M, Krober N. Circumferential viscodilation and tensioning of Schlemm canal with temporal clear corneal phacoemulsification cataract surgery for open-angle glaucoma and visually significant cataract: One year results. J Cataract Refract Surg 2008; 34:433-440.

8. Fea AM. Phacoemulsification versus phacoemulsification with micro-bypass stent implantation in primary open-angle glaucoma. J Cataract Refract Surg. 2010;36:407-412.

9. McKinnon SJ, Goldberg LD, Peeples P, Walt JG, Bramley TJ. Current management of glaucoma and the need for complete therapy. Am J Manag Care. 2008;14:S20-27.

10. Cantor LB, Katz LJ, Cheng JW, Chen E, Tong KB, Peabody JW. Economic evaluation of medication, laser trabeculoplasty and filtering surgeries in treating patients with glaucoma in the US. Curr Med Res Opin. 2008;24:2905-2918.

Editors' note: Dr. Solomon has financial interests with Glaukos (Laguna Hills, Calif.).

Contact information

Solomon: Kerry.Solomon@carolinaeyecare.com

Related articles:

Zonular issues can complicate cataract surgery by Michelle Dalton EyeWorld Contributing Writer

Experts discuss controversies in cataract surgery by Chiles Samaniego EyeWorld Asia-Pacific Senior Staff Writer

Myopic eyes and cataract surgery: Weve come a long way by Dagny Zhu, MD, Lloyd Cuzzo, MD, and Vivek Patel, MD

Help patients relax for better cataract surgery cooperation by Vanessa Caceres EyeWorld Contributing Writer

Managing iris prolapse when sealing the wound during cataract surgery by Daniel H. Chang, MD

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