Liz Meszaros

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-A new premium daily disposable contact lens (Biotrue ONEday) from Bausch + Lomb is made from a proprietary material (HyperGel) that combines the features of conventional hydrogel and silicone hydrogel material. Launched at the annual conference of the British Contact Lens Association last month, this new lens provides the optimal conditions for maintaining not only all-day comfort, but good ocular health as well. 

The contact lens provides the maximum amount of moisture of any daily disposable lens available today, even after 16 hours of wear, the company noted. The lens contains 78% water-the same water content as the cornea-and delivers virtually the same oxygen level as the open eye. 

"The aerodynamic blueprints of some automobiles, for example, are based on and take bio-inspiration from the aerodynamics of fish," Dr. Künzler said. "In the ocular world, the Crystalens, for example, is [made of] a material we developed several years ago that is based on the natural accommodating lens of the eye. We recently introduced a multi-purpose solution (Biotrue) that is bio-inspired and contains hyaluronic acid, which is a component of the eye and is responsible for lubrication." 

Similarly, the outer surface of the new daily disposable contact lens is designed to mimic the lipid layer over the tear film, which prevents dehydration of the lens by holding water in the lens. To achieve this, Dr. Künzler and colleagues also incorporated surfactant chemistries that are enriched at the surface of the lens.			

"The lipid layer of the eye is made up of naturally occurring surfactants," Dr. Künzler said. "These surfactants form a boundary layer, a lipid layer that minimizes and almost prevents water from going through it, yet maintains good wetting and lubricity." 

Surfactants are incorporated into the lens material, they do not leach out; they are enriched at the lens surface and remain there, and mimic the natural lipid layer of the eyeball. In the past, lens dehydration was a problem, and sometimes, lenses dehydrated so much that they actually took water from the eye, a phenomenon known as epithelial dehydration, he added. 

Developing a material that has 78% water and has a chemistry that prevents dehydration is a breakthrough, Dr. Künzler noted. 

Recent studies of the new daily disposable contact lens have shown that, even after 16 hours of wear, the lens was losing, on average, only 1.5% water, compared with other lenses, which lose 6% to 8% water under normal conditions. To assess dehydration in the lens, clinicians also conducted studies in humidity-controlled rooms, with a relative humidity of around 5%, comparable to desert conditions. Even under such arid conditions, water loss with the new daily disposable contact lens was only 1.5%, Dr. Künzler said. 

Articles

A new premium daily disposable contact lens from Bausch + Lomb is made from a proprietary material that combines the features of conventional hydrogel and silicone hydrogel material.

Bausch + Lomb new daily disposable lens debuts

-In  patients who present with both cataract and 

, ophthalmologists have the option of performing cataract extraction  alone or simultaneously with Descemet’s stripping automated endothelial keratoplasty (DSAEK), said 

 conference. Careful patient selection  and informed consent are vital to choosing the proper approach.

Dr. Aldave explored how to determine the best options for  these patients. Should surgeons perform just cataract surgery or cataract  surgery and DSAEK?

“If there’s any epithelial edema at all, that patient should  have a combined procedure,” said Dr. Aldave, who is  associate professor of ophthalmology, The Jules Stein Eye Institute, University  of California-Los Angeles. “When patients come to us with corneal edema and  subepithelial scarring, it’s from epithelial edema that has been present for a  few months. You don’t typically get subepithelial scarring from stromal edema. That patient should have cataract surgery and DSAEK.”

What about in the patient without epithelial edema, but with  stromal edema?

“If they have to wait a while every morning before their  vision is optimized (to read the newspaper, for example), then the corneal  edema is interfering with their lifestyle,” Dr. Aldave said. In these patients,  he recommends a combined procedure.

When performing an exam in these patients, which  measurements are significant? According to Dr. Aldave, the cutoff for  pachymetry measurements is not absolute, although he uses a cutoff of  approximately 640 µm.

“If the cornea is thicker than that, I do a combined  procedure,” he said, adding that if pachymetry is less than 640 µm, without  epithelial edema, cataract surgery alone is typically recommended.

“But if the pachymetry is borderline, I target a myopic  postoperative refractive error, knowing that if they subsequently require  DSAEK, it will induce a hyperopic shift,” he added.

Dr. Aldave explained that he does not typically use endothelial  cell counts to make the decision between performing cataract surgery versus a  combined procedure, but if the endothelial cell density is less than 500  cells/mm², perhaps a combined procedure should be considered.

Dr. Aldave also offered some valuable advice about choosing the  IOL type and power in patients with Fuchs’ dystrophy:

Multifocal IOLs are contraindicated in these  patients because of the visual aberrations that result from endothelial guttae  (when cataract surgery alone is performed) and decreased contrast sensitivity  following DSAEK (when a combined surgery is performed).

Toric IOLs are appropriate to place, as long  as that patient remains a candidate for DSAEK should corneal endothelial  compensation occur post-operatively.

“Although the astigmatic effects of DSAEK are  somewhat unpredictable, especially if a clear corneal incision is used, we have  found that the effect is fairly small in the majority of patients. As long as  you have good informed consent, I think that’s appropriate,” he noted.

Accommodating IOLs may also be considered,  with good informed consent, although, stressed Dr. Aldave, patients must be  informed that a refractive touch-up will likely be needed if DSAEK surgery is  subsequently required due to the hyperopic shift that typically occurs with  DSAEK surgery.

“I typically target a residual refractive error of about –1.00 to  –1.25 D when choosing an IOL for a patient undergoing a combined cataract  surgery and DSAEK. With the move to ultra-thin DSAEK, and now with the advent  of Descemet’s membrane endothelial keratoplasty, surgeons should probably  target a little less myopia, perhaps –0.75 to –1.00 D,” he explained.

Dr. Aldave also touched upon the performance of YAG capsulotomy in  patients with Fuchs’ corneal dystrophy. During DSAEK, he related, he has noted  the presentation of vitreous into the anterior chamber during surgery in  approximately 5% to 10% of patients. Some of these patients have an IOL in the  bag, but have had either a large-sized or eccentric YAG capsulotomy, which  allows the movement of vitreous around the lens optic into the anterior chamber  when the lens-iris diaphragm moves posteriorly during DSAEK surgery, he said.

“If you decide a YAG capsulotomy is needed in a patient who has  Fuchs’ dystrophy, keep it small and keep it centered so that if they come to me  for DSAEK, I won’t have to do a vitrectomy during the procedure,” Dr. Aldave  added.

When performing both cataract surgery and DSAEK, consider how to  get reliable K values, continued Dr. Aldave. Topography should be done prior to  the onset of corneal epithelial edema in phakic patients who have Fuchs’ dystrophy.  Prior topographies are important, especially in patients who go on to develop  epithelial edema, because topography performed after edema has developed will  not be accurate, and could be a full diopter off, he noted.

In the setting of fine microcystic edema, when prior topography  has not been performed, glycerin application in the clinic can be very helpful,  he continued. This may be successful in resolving the epithelial edema,  resulting in a reliable topography. In patients who present with epithelial  bullae, glycerin will not help, however. In these cases, Dr. Aldave has  patients come in for a pre-op visit 1 week before surgery, he performs corneal  epithelial debridement, and then he performs corneal topography.

Simultaneous surgeries have many advantages, including a single  surgery and faster rehabilitation for the patient, although sequential surgery  may be indicated in particular circumstances, Dr. Aldave continued.

“The downside when you are doing DSAEK and cataract surgery  simultaneously is that you must keep your capsulorrhexis small so the IOL stays in the bag when you insert the donor cornea,” he said. “If you’ve got a dense cataract, trying to remove it safely through a small capsulorrhexis can be problematic. You absolutely cannot have an anterior capsule tear, because the significant posterior movement of the IOL and capsular bag that occurs during air injection into the anterior chamber could cause the tear to extend posteriorly.”

“The advantage of performing cataract surgery as an initial  separate procedure prior to DSAEK is that a larger capsulorrhexis can be made, so that at the time of DSAEK surgery, which will be a couple months later, the lens will be fibrosed in the bag,“ he noted. “The downside is two trips to the operating  room, which is less convenient for out-of-town patients and more expensive for self-pay patients.”

His preference is simultaneous cataract and DSAEK for all  patients, except in those who are at high risk for intraoperative floppy iris  syndrome, who have high hyperopia secondary to a short axial length, and  eyes with known zonular instability.

“I use a 5-mm clear coronal incision for DSAEK surgery. The last  thing I want is iris prolapsing out of that incision as I’m trying to bring the  DSAEK lenticle into the eye,” he noted.

“I’ve noted the movement of the residual air bubble that remains  at the end of the procedure posterior to the iris in a number of cases of  combined DSAEK and cataract in patients with high hyperopia and very short  eyes,” he added. “Thus, in someone who has very high hyperopia, typically an eye that is  more than +4 D hyperopic, I will perform sequential procedures,” he said. “If there  is any concern regarding zonular integrity, I will also perform cataract  surgery and DSAEK as sequential procedures as well.”

Dr. Aldave has no financial disclosures relevant to the  topic.

Anthony Aldave, MD, explains when cataract extraction should be done alone or with Descemet's stripping automated endothelial keratoplasty (DSAEK).

Combined or separate cataract, DSAEK procedures in Fuchs' dystrophy?

The recent issuance of revised recommendations for hydroxychloroquine (HCQ) (Plaquenil, Sanofi) retinopathy screening from the American Academy of Ophthalmology (AAO) will have substantial effects on practicing ophthalmologists, said 

 "Many ophthalmologists have to deal with treating for antimalarial toxicity, specifically for HCQ- or chloroquine (CQ)-induced toxicity, although the former is more commonly used in the United States," said Dr. Dunn, who also is director of the residency program at the Wilmer Eye Institute. 

In addition, both agents also have acute effects on photoreceptors, and bind to melanin in retinal pigment epithelium (RPE).

Some sequelae of therapy are not significant, Dr. Dunn noted. 

"For example, all patients who are [taking] the standard dose of HCQ at 400 mg/d, will have corneal verticillata," he said. "But this is benign." 

The problematic toxicities, however, are those that affect the retina. 

"These can manifest early visually, with paracentral scotomata, and patients may complain of difficulty reading," he said. 

Patients may also have an early bull's-eye maculopathy, with a ring of RPE depigmentation that spares the fovea. This can progress both clinically and functionally if the drug is not discontinued. 

The incidence of maculopathy in patients taking HCG and CQ is not entirely clear, Dr. Dunn said. Various studies have examined this, and according to a large study published in 2010, 6.8/1,000 users will develop maculopathy.

Toxicity depends both on the duration and the cumulative dose of the drug. The incidence is very low during the first 5 years of use, but increases over time, with a sharp rise in incidence after 5 to 7 years. The risk is even higher after 15 to 20 years of exposure. Factors that increase the likelihood of toxicity include taking more than 400 mg/d, increasing age, and pre-existing retinal disease. 

In addition, "older patients are more at risk for toxicity, and because of the metabolism of the drug, those with renal or hepatic dysfunction are at greater risk," Dr. Dunn noted. 

The recent issuance of revised recommendations for hydroxychloroquine retinopathy screening from the American Academy of Ophthalmology will have substantial effects on practicing ophthalmologists.

Hydroxychloroquine guidelines screen for toxicity risk

-Advances in ophthalmic surgery, especially vitreous suction-cutting devices, have made the  treatment of congenital cataracts in the pediatric population easier and more effective, said Hee-Jung  Park, MD, MPH. Yet, many challenges still exist for surgeons with these smallest patients, including safety and good long term results. 

"Advancement in instrumentation has made pediatric cataract surgery safer and more reliable," said  Dr. Park, assistant professor of ophthalmology, Johns Hopkins University School of Medicine, Wilmer  Eye Institute, Baltimore. 

"Addressing the needs of pediatric cataract patients worldwide, we need [to develop] better IOL  technology for pediatric eyes that will allow for smaller incisions during surgery, and prevent  complications and the need for further surgery."			

Also, the low scleral rigidity makes it difficult to maintain the chamber during surgery.  

"It's about four times more pliable and has only half the tensile strength of the adult sclera," Dr. Park said. 

In children, surgeons must also deal with wide-ranging pathology, including fibrous membrane, calcification, and iris-lens adhesion.  

"You have to be ready for surprises when you . . . operate on these eyes," she said. "Even after successful cataract surgery, surgeons will be  faced with vigorous inflammatory response, posterior capsular opacification, and secondary membrane formation." 

The advent of vitreous suction-cutting devices has revolutionized pediatric cataract surgery, making it  safer and more reliable, according to Dr. Park. This technology allows surgeons to perform anterior  capsulotomy by means of vitrectorhexis, removal of lens, posterior capsulotomy, and limited anterior  vitrectomy-all with the same device through a small incision. The latter steps reduce the development of secondary membrane formation, and thus, reduce the number of surgeries.  

"We've also gone down  in size from 20 gauge to 25 gauge, and perhaps in the future, even to 27  gauge," Dr. Park said. 

Other helpful surgical tools include operating microscopes, viscoelastic materials with high molecular   weight, intraocular scissors, endgrasping forceps, and capsulorhexis forceps.  

"Most importantly, advances in IOL material and design now allow insertion of a lens through a small   incision, which makes it possible for us to think about inserting a lens into an infant's eye," she said. 

Although surgery has become more refined and safer, there remain extra concerns when it comes to  pediatric cataract surgery, Dr. Park continued. One of the most important factors to consider is the   timing of surgery. 

The incidence of aphakic glaucoma after cataract surgery in children ranges from 15% to 21% at 5  years. The rate of aphakic glaucoma is higher if surgery is performed within 4 weeks after birth. Visual  outcomes decline, however, if cataract surgery is performed after 6 weeks of age. 

"This gives us an optimal window of time between 4 to 6 weeks of age to perform the cataract surgery,  and this is what I recommend for my patients," she said.  

Successful cataract surgery is only a small  stepping stone to visual correction in young children,  according to Dr. Park. Surgeons then must figure out how best to correct the refractive error. IOL  implantation and contact lenses are two choices to consider. 

Advances in ophthalmic surgery, especially vitreous suction-cutting devices, have made the treatment of congenital cataracts in the pediatric poulation easier and more effective.

Liz Meszaros

Articles

Combined or separate cataract, DSAEK procedures in Fuchs' dystrophy?

Hydroxychloroquine guidelines screen for toxicity risk

Congenital cataract still a challenge

Bausch + Lomb new daily disposable lens debuts