Treating patients with AMD who also require cataract surgery

August 15, 2013

There are numerous methods and factors surgeons should examine for patients with age-related macular degeneration and who require cataract surgery to avoid future problems.

Take-Home:

There are numerous methods and factors surgeons should examine for patients with age-related macular degeneration and who require cataract surgery to avoid future problems.

Dr. Olsen

By Lynda Charters; Reviewed by Timothy W. Olsen, MD

Atlanta-Treating patients with age-related macular degeneration (AMD) becomes even more complicated when the effect of other potential drug use is considered, said Timothy W. Olsen, MD.

Prophylactic antibiotics

Cataract surgery is one of the most common ophthalmic procedures performed, while topical antibiotics have traditionally been an important part of postoperative care.

Cataract surgeons should ask patients being treated with intravitreal injections for AMD if they are also receiving routine antibiotics after the injections from the retina surgeon.

“When patients are asked to use prophylactic antibiotics by the retina specialist, this is not typically something that happens only once,” said Dr. Olsen, F. Phinizy Calhoun Sr. Professor and Chairman, Department of Ophthalmology, Emory University, Atlanta. “Some retina specialists still routinely administer topical antibiotics following each injection.

“Some suggest administration for 3 days following each injection,” he said. “While this is becoming less common, such patients can receive up to 24 injections during a 2-year period and (this) represents overuse of broad-spectrum antibiotics.”

A recent study1 of ocular bacterial flora found that eyes treated with frequent antibiotics had significantly higher antibiotic resistance as measured by minimum inhibitory concentrations.

“Eyes treated with topical antibiotics are developing more resistance to bacterial strains,” Dr. Olsen said. “We are probably doing very little good for these patients and may actually be creating a harmful, more resistant ocular flora.”

The study recommended that routine prophylactic use of antibiotics after intravitreal injections be discouraged-a position also endorsed by the American Academy of Ophthalmology and the Choosing Wisely Campaign.

Should these patients undergo cataract surgery and develop endophthalmitis, the infecting agent may theoretically originate from a more drug-resistant strain.

Anti-VEGF drugs

Intravitreal injections of anti-vascular endothelial growth factor (VEGF) drugs for AMD are characterized by peak-and-trough pharmacokinetics in the vitreous. The peak-and-trough effect raises the question about the optimal time to perform cataract surgery.

Pharmacologically, Dr. Olsen said, the ideal time for cataract surgery may be near the end of the anti-VEGF cycle, which is closer to the trough.

For example, cataract surgery 1 week before the next scheduled injection would minimize the anti-VEGF drug dilution that occurs as a result of the fluidics used intraoperatively.

The eye would have the chance to heal for one week, with a lower-level tissue anti-VEGF level and be able to tolerate the next scheduled injection.

In contrast, cataract surgery 1 week after an anti-VEGF injection would risk dilution of the peak pharmacokinetic effect of the anti-VEGF agent.

Cataract surgeons have expressed a valid concern that an anti-VEGF injection 1 week after cataract surgery could risk opening or dehiscence of the cataract incision.

A compromise may be to place a 10-0 nylon suture in the cataract wound, give the injections as scheduled, and then eventually remove the suture after the cataract wound has stabilized.

Another option is to time the cataract surgery to correspond with the next scheduled anti-VEGF injection, and ask the cataract surgeon to deliver the agent at the conclusion of the case.

Despite effective treatment using anti-VEGF agents, AMD continues to progress.

Studies2 are suggesting that at 5 years after treatment initiation, patients’ vision slowly declines.

Examination of findings

To help cataract surgeons gauge the patients’ status in 5 years, Dr. Olsen considered a patient with large drusen and pigment clumping who needed to undergo cataract surgery.

Based on the simplified grading scale,3 the patient likely had a 50%, 5-year risk of progression to advanced disease in at least one eye.

Dr. Olsen underscored the importance of risk-assessing the macula and ensuring that at-risk patients take antioxidant supplements (Age-Related Eye Disease Study (AREDS)) and adhere to a healthy lifestyle that includes green leafy vegetables, fresh fruit, fish, lower fat, and avoidance of smoking.

In another patient with non-central geographic atrophy (GA), Dr. Olsen said a point to consider is that non-central GA can progress to involve the central macula, making the choice of a multifocal IOL over a monofocal lens a poor choice.

The AREDS study4 indicated there is an average 2-mm/year expansion of GA. Such a patient should not be considered a good candidate for a multifocal IOL.

A patient with GA, pigmentary changes, and large soft drusen is at risk for bilateral disease.

Another consideration for patients with advanced AMD and cataract would be to discuss the FDA-approved ophthalmic telescope implant (Implantable Miniature Telescope [by Dr. Isaac Lipshitz], VisionCare). Proper rehabilitation assessment is critical for identifying good candidates for the telescope implant.

The role of a yellow-tinted IOL may also offer theoretic advantages for slowing AMD progression, yet this claim is unsupported by clinical data.

Some argue5 that a yellow tint diminishes night or dark-adapted vision, interferes with the diurnal cycle, promotes affective disorders (depression), and may limit contrast sensitivity in certain conditions.

“Lens selection is important in patients with AMD, and informing patients about their individual risk of progression is critical,” Dr. Olsen said. “Surgical pre-assessment using visual rehabilitation measures is essential when selecting patients who are considered candidates for the [telescope implant].”

Experimental methods of drug delivery

Various future options, such as microcannulae and microneedles, could be used to access the suprachoroidal space-a technology developed as a joint project among researchers at Emory, Georgia Tech, and the University of Minnesota, Dr. Olsen noted.

These technologies are entering the developmental stages and early clinical trials with industry.

Other options in the pipeline include:

·      Punctal plugs loaded with pharmaceuticals.

·      The lens capsule as a reservoir for drug release.

·      IOL implant itself as a drug repository.

·      Nanoparticles used in novel and innovative ways.

“It is important to ask patients about use of topical antibiotic prophylaxis,” Dr. Olsen said. “The timing of cataract surgery in relation to administration of anti-VEGF therapy should be planned and coordinated effectively.

"For patients with AMD, risk-assess, communicate risk, and encourage patients to use antioxidant supplements and live a healthy lifestyle,” he said.

 

References

1. Yin et al. Antibiotic resistance of ocular surface flora with repeated use of a topical antibiotic after intravitreal injection: JAMA Ophthalmology 2013;131:456-461.

2. Singer et al. HORIZON: an open-label extension trial of ranibizumab for choroidal neovascularization secondary to age-related macular degeneration. Ophthalmology. 2012;119:1175-1183.

3. Ferris et al. A simplified severity scale for age-related macular degeneration: AREDS Report No. 18. Arch Ophthalmol. 2005;123:1570-1574.

4. Lindblad et al. Change in area of geographic atrophy in the Age-Related Eye Disease Study: AREDS report number 26. Arch Ophthalmol. 2009;127:1168-1174.

5. Mainster MA, Turner PL. Blue-blocking IOLs decrease photoreception without providing significant photoprotection. Surv Ophthalmol. 2010; 55:272-289.

 

Timothy W. Olsen, MD

E: tolsen@emory.edu

Dr. Olsen has received no support from industry. He is the recipient of several grants (NIH/NIA:  RO1 AG025392; NIH/NEI:  R44 EY016229, and P30 EY006360).  Departmental support is provided by an unrestricted grant from Research to Prevent Blindness, NY.

 

Subscribe to Ophthalmology Times to receive the latest clinical news and updates for ophthalmologists.