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July/August 2008

 
News in Review
A Look at Today's Ideas and Trends
 
 

CSC May Be Associated With Viagra

Physicians and ophthalmologists treating patients who are taking sildenafil [Viagra] or other erectile dysfunction drugs should consider the discontinuation of these agents if a patient presents with central serous chorioretinopathy,” said Frederick W. Fraunfelder, MD, associate professor of ophthalmology at Oregon Health & Science University in Portland.

This recommendation is based on results of a retrospective, observational review of 1,500 reports of sildenafil-related ocular side effects. The cases were culled from postmarketing surveillance databases at the FDA, the World Health Organization and the National Registry of Drug-Induced Ocular Side Effects, and a search of the literature. Research revealed 11 cases of CSC in men who were taking the drug.1 The men were 33 to 70 years old; dosage ranged from 50 to 100 mg per day; intake ranged from one to six times per week; and duration of therapy ranged from one day to two years.

According to Dr. Fraunfelder, there is some evidence of an association between erectile dysfunction (ED) drugs and the development of CSC, although the authors concede that much of their data is inconclusive, due in part to the incomplete nature of postmarketing surveillance data and to the fact that CSC can be cyclical.

“What makes the association between ED drugs and CSC more likely is the three positive rechallenge cases that we identified. When sildenafil was reintroduced, the symptoms returned. This is compelling evidence that the symptoms are related to the drug. Nevertheless, this occurred in only three of the cases we examined so it is difficult to draw definitive conclusions from the data,” said Dr. Fraunfelder.

In the remaining eight patients in whom sildenafil-related side effects were identified, dechallenge occurred. Two of these patients did not completely recover their vision even after the drug was withdrawn. “We cannot explain why this occurred; in some cases, the effects of CSC are permanent,” said Dr. Fraunfelder.

Because the data are lacking in scientific evidence, the researchers determined that the relationship between sildenafil and CSC should be characterized as “possible” but may also be explained by “concurrent disease or the presence of other drugs or chemicals,” although Dr. Fraunfelder pointed out that none of the patients was taking systemic or ocular steroids. Further, “the very few case reports relative to the millions of patients who use sildenafil make the association of CSC due to sildenafil rare,” he said.

“While we cannot classify the side effects as certain or probable, we suggest that any clinician whose patient experiences vision loss while taking ED drugs consider their withdrawal,” said Dr. Fraunfelder. He and his coauthor further stated that if the patient wants to continue with ED therapy, both the prescribing physician and ophthalmologist should obtain informed consent before drug therapy is resumed, and the ophthalmologist should watch for signs of positive rechallenge.

—Leslie Burling-Phillips

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Suspected cases of sildenafil-associated CSC and/or related vision loss should be reported to the National Registry of Drug-Induced Ocular Side Effects (www.eyeregistry.com), Food and Drug Administration (www.fda.gov/medwatch/index.html), World Health Organization (www.who-umc.org), or Pfizer (www.pfizer.com).
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1 Fraunfelder, F. W. and F. T. Fraunfelder. Retina 2008;28:606–609.

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Cornea Update 

DSAEK May Cause Hyperopic Shift in Some Patients

A hyperopic shift occurs after Descemet’s stripping automated endothelial keratoplasty surgery, both in pseudophakic and “triple” patients (DSAEK plus phaco and IOL implantation), according to a group of researchers at Duke University Eye Center.1

“In addition, as the graft size increased, we found more hyperopic shift,” noted Bokkwan Jun, MD, PhD, a research fellow there and lead investigator of the study.

These findings have significant implications for cataract surgery patients, said Dr. Jun. “For DSAEK triple patients or phakic cataract patients who will need DSAEK surgery, we should adjust their target power to be more myopic,” he said. “And for pseudophakic patients, we can counsel them preoperatively about the possibility of postoperative refractive change.”

Dr. Jun has been working as a research fellow at Duke for two years under the preceptorship of Terry Kim, MD, associate professor of ophthalmology. The focus of Dr. Jun’s clinical research and experimental study has been on corneal wounds in cataract surgery, parameters in phacoemulsification, including ultrasound and temperature, and the evaluation of DSAEK surgery outcomes, including refractive change and optical coherence tomography evaluation.

Drs. Jun and Kim began their research project after discovering refractive changes in DSAEK pseudophakic patients. They wondered whether proper lens power determination in cataract surgery might be affected by this refractive change.

They reviewed all DSAEK patient charts between August 2005 and December 2006, excluding patients with other ocular issues such as glaucoma, macular disease and optic neuropathy. “We compared the patients’ recent preoperative refractive error and postoperative error at last follow-up,” Dr. Jun said. “We also tried to see if there was a correlation between these refractive changes and factors such as graft central thickness and graft diameter.”

Their findings corroborate the findings published by Yoo et al., who found a similar correlation of induced hyperopic shift with increased peripheral DSAEK graft thickness.2

The Duke study included 45 eyes of 44 patients who had at least three months of follow-up after DSAEK and had refractive data preoperatively and at last follow-up. Overall refractive change in the 45 eyes was +0.88 D. After subgroup classification, the mean refractive change was +1.15 D in 17 eyes that underwent DSAEK triple surgery and +0.71 D in 28 pseudophakic DSAEK eyes.

“These findings indicate that there may be hyperopic shift after DSAEK surgery, and that we may need to choose an IOL power aimed for more myopia in patients that are likely to need DSAEK surgery in the future,” Dr. Jun said.

—Lori Baker Schena

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1 Jun, B. et al. Refractive change following DSAEK surgery and its correlation with graft thickness and diameter. Presented at the American Society of Cataract and Refractive Surgery, Monday, April 7, 2008, Chicago, Ill.
2 Yoo, S. H. et al. Arch Ophthalmol 2008;126:268–270.

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Trauma News 

Buckle Up for Eye Safety

During the nearly four decades since the introduction of air bags, fatalities resulting from motor vehicle accidents have decreased by more than 30 percent. However, deployment of air bags has been associated with an estimated 5 percent incidence of ocular injuries.

Although the scientific literature is sparse, it has been hypothesized that seatbelt use may delay contact with the deploying air bag and therefore could reduce the risk of ocular injuries.

Sunil K. Rao, MD, chief resident of ophthalmology at Brown University, and his colleagues conducted a retrospective chart review of drivers and front seat passengers who were involved in a crash with air bag deployment and assessed at the Rhode Island Hospital eye clinic.1 They explored the association between seatbelt use, ocular injuries and visual acuity outcomes after accidents with air bag deployment.

More than 9,000 patient charts were reviewed, and 47 patients met study inclusion criteria, for a total of 79 affected eyes. Twenty-six patients had worn a seatbelt, and 21 had not.

Injury severity scales were modified from prior studies to include specific diagnoses that were previously vague or unspecified. “We wanted to create a uniform classification system that ophthalmologists can use for trauma studies in general,” Dr. Rao explained.

Injuries were evaluated along a three-tier classification hierarchy ranging from mild (Type I) to moderate (Type II) to severe (Type III). Lid swelling, subconjunctival hemorrhage and corneal abrasion occurred among both restrained and unrestrained patients. However, “we found that if an individual wore a seatbelt, he or she was less likely to have injuries that resulted in legally blinding vision loss. Futhermore, posterior segment injuries occurred solely in unrestrained patients, and orbital fractures occurred more frequently among the unrestrained group, who were also more likely to have a visual acuity of 20/200 or worse,” said Dr. Rao. “One clinical benefit of these findings is that we can now ask patients if a seatbelt was worn or not to determine if they are more or less likely to be associated with legally blinding vision.”

—Leslie Burling-Phillips

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1 Rao, S. et al. Ophthalmology 2008;115:573–576.

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Glaucoma Update 

Thick CCT May Reduce Efficacy of Glaucoma Meds

Central corneal thickness made news six years ago when the Ocular Hypertension Treatment Study showed that CCT was a risk factor for development of glaucoma independent of its effect on IOP measurement. Now CCT is making news again.

In a retrospective study, a team from the University of Nebraska reviewed its research records to determine what effect, if any, CCT had on the efficacy of topical ocular hypotensive medications in 115 patients with ocular hypertension. Data from 97 ocular normotensive volunteers were used for comparison. Corneal measurements were made by slit-lamp pachymetry and IOP by pneumotonometry. Subjects were divided into “thick CCT” (> 540 µm, n = 52) and “thin CCT” ( 540 µm, n = 63) groups, and drug-induced changes in IOP were evaluated.1

“We found that eyes with thinner corneas had significantly lower IOPs after one week of topical ocular hypotensive drug treatment than eyes with thicker corneas, even though these IOPs were statistically similar before treatment,” said Carol B. Toris, PhD, a study coauthor and professor of ophthalmology and director of glaucoma research at the University of Nebraska in Omaha.

Over the years, the team at Nebraska has conducted many studies of fluid dynamics in the eye, looking at pressure, inflow and outflow and CCT, and the effects of various IOP-lowering drugs.

“With the data readily available,” said Dr. Toris, “we decided to go back and take another look at CCT and IOP. While other researchers have looked at corneal thickness and IOP before, our study is unique in that we have baseline data on patients with ocular hypertension who are on no ocular medications, and data after one week of topical treatment with a variety of drugs.”

Within a normal range and in healthy eyes, there’s nothing wrong with thick corneas, said Dr. Toris. But, she added, “The cornea is quite a barrier. When you apply a drug to the cornea, less than 5 percent actually gets into the eye, and it appears that this is even less in eyes with thicker corneas.”

—Nancy Bronstein

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1 Johnson, T. V. et al. Glaucoma 2008;17:89–99.

EyeNet thanks Christopher Rapuano, MD, and Brian Francis, MD, for their help with this issue’s News in Review.

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