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

-The  burden of retinopathy of prematurity (ROP) is great, and researchers are still  working to find the most effective and safest treatments, said David Barañano,  MD, PhD, at the 24th annual Current Concepts in Ophthalmology  meeting.

ROP remains one of the leading causes of blindness in children,  began Dr. Barañano, who is assistant professor of ophthalmology, Johns Hopkins  University School of Medicine-Wilmer Eye Institute, Baltimore. In the United  States, about 500 children per year lose their vision due to ROP. ROP has a stereotyped disease course, and usually becomes apparent by 32 weeks gestational age. The threshold incidence peaks at 37 weeks gestational age, he  said.

In 1984, the international community issued a classification  system for this disease based on stages that reflect the progression of the  disease:

Stage 1 is the  mildest, and is signified by a line that demarcates avascular retina from  vascular retina.

Stage 2 develops  when a thick, elevated ridge develops.

Stage 3 occurs  when epiretinal neovascularization occurs.

Stage 4 occurs  when the vessels contract and partially pull the retina off the back of the  eye.

Stage 5 consists  of retrolental fibroplasia, or total retinal detachment.

“It is important to understand that at any point-especially during  the first few stages-this disease can regress either spontaneously or with  appropriate treatment,” Dr. Barañano said.

“In a state of relative hypoxia, the avascular retina in the  periphery produces the pro-angiogenic factors that lead to the problem. It  makes sense that destroying the avascular retina may halt the process, and this  was first demonstrated in the 1980s with the CRYO-ROP trial,” he added.

Careful screening combined with timely and complete ablation of  peripheral avascular retina is highly effective for most cases of ROP, said Dr  Barañano. In addition, careful attention to oxygen exposure can reduce the rates of ROP. Finally, although off-label, the use of bevacizumab (Avastin, Genentech/Roche) in these young patients is likely to play an important role in severe posterior disease, but the indications, timing, and follow-up are unknown at this time.

Laser treatment has been demonstrated to be at least as  efficacious as cryotherapy in treating ROP, continued Dr. Barañano. The Early  Treatment of Retinopathy of Prematurity (ETROP) Trial refined treatment  criteria to include those with a 15% chance of developing a threshold  characteristic. These infants were treated earlier than they would have been  otherwise and did far better. Only 9% of infants treated early developed  unfavorable anatomy compared with 16% of conventionally managed infants.

“There is clearly room for improvement, even with the refined  ETROP criteria,” Dr. Barañano said. “One of the biggest improvements is the  screening, especially in developing countries, where improvements in acute care  have outpaced ophthalmic monitoring of these infants. There is a pressing need  for improved screening, whether through telemedicine or computer-assisted image  analysis to detect plus disease.”

One  option that is continuously being explored is efforts to augment oxygen levels in infants with ROP, continued Dr. Barañano. Oxygen  therapy is usually begun in stage 1 of the disease, when the infant is in a  state of relative hyperoxia. During this time, relatively lower oxygen levels  may minimize the halting of the normal vascular process. A physiologically  reduced oxygen protocol has been adopted at many NICUs over the past 5 years,  but it is rather complex, and requires state-of-the-art oxygen monitoring  systems and specialized training for the staff to ensure appropriate  incremental changes in oxygen saturation. Chow and colleagues analyzed  retrospective data on this new protocol, and found a dramatic decrease in  severe ROP from 12% to 2.5%. A study by Sears et al. and one by  Wright et al. both found similarly dramatic decreases in the rate of severe  ROP.

Oxygen therapy nearly abolished the need for laser in these cohorts.  None of these studies were powered by mortality, however, noted Dr. Barañano,  nor were they randomized trials.

“There was a lot of excitement about these new oxygen protocols,  and how they might decrease our ROP burden. Unfortunately, two very large  randomized, controlled trials recently found that there is an increased infant  mortality with the new oxygen protocol. For this reason, some NICUs are backing  away from this new oxygen protocol,” he explained.

The advent of these trials that showed oxygen therapy perhaps to  be detrimental in infants with ROP highlighted the necessity to explore  different treatment options. One of these options involves addressing the  pro-angiogenic factors that are involved in the pathogenesis of ROP, Dr.  Barañano explained.

“Bevacizumab and ranibizumab (Lucentis,  Genentech/Roche) are anti-vascular endothelial growth factor (VEGF) agents, and  seem to be a natural choice for a disease such as ROP,” Dr. Barañano said.

In 2007, researchers first reported a dramatic effect in infants  with these two anti-VEGF agents, and since then, at least six large case series  have described the use of bevacizumab.

“The results are compelling, and infants experienced a very rapid  regression of plus disease in all cases. Numerous [researchers] have reported  complete avoidance of laser, and they have beautiful examples of  normal-appearing vessels actually progressing beyond the demarcation after the  treatment,” Dr. Barañano noted, adding that there was about a 5% incidence of  contraction and cicatricial changes accelerated by the injection.

“There has been a growing consensus among those who treat ROP that  bevacizumab has a role as rescue therapy in situations in which the clinician  is unable to treat the eye with laser, either due to anterior rubeosis,  vitreous hemorrhage, or cataract. Before the availability of intravitreal  bevacizumab, these eyes [would] end up with no light perception, and  bevacizumab may reverse the process,” Dr. Barañano stressed.

Other rescue therapy indications may include those eyes in which  persistent avascular activity occurs, despite complete laser treatment.

“In cases where the complete avascular retina is treated and there  is still persistent avascular activity, bevacizumab may have a role as rescue,”  he said.

Finally, there are the eyes that have already undergone detachment  but have a considerable amount of vascular activity to the point where surgery  would be unsafe. In these cases, bevacizumab used as an adjunct allows for  surgery to be performed at an earlier time, when there is still some hope for a  successful outcome.

 “In these very fragile and  young infants, we are mindful that there are some very serious safety  concerns,” Dr. Barañano said.

Adverse ocular effects have been reported. In one of the first  reports of the use of bevacizumab in infants, related Dr. Barañano, a  23-week-old infant developed a severe cicatricial contractual detachment 24  hours after injection.

“This was thought to be due to the rapid regression of vascular  proliferation. There was also an example of a choroidal rupture 24 hours after  injection in another infant,” he noted.

The more pressing question, however, is whether there are  significant systemic consequences to the use of potent anti-angiogenic therapy  for these very fragile patients. Although the safety profile of these agents  for adults is good, concerns about their effects in such tiny patients is  great, noted Dr. Barañano.

“In infants with ROP, the blood-eye barrier is not fully  established,” he said. “Bevacizumab injected intravitreally actually shows up  [at] measurable, pharmacologically relevant levels in the serum of these infants  as early as 24 hours after injection,” Dr. Barañano explained. “Not only does  the medicine end up in the blood, but the serum levels of VEGF actually drop in  these children almost 10-fold. When we think of the physiologic angiogenesis  that is occurring in the lungs and in the brains in these infants at this time,  this finding should give us pause,” he stressed.

Despite these concerns, there is a growing movement toward using  bevacizumab as primary therapy in these infants, as contrasted with rescue  therapy. Some of the potential theoretical advantages cited for this approach  include the potential to spare some visual field and prevent myopia related to  laser ablation.

“Laser treatment is definitely associated with cataract, and there  can also be angle damage and potentially strabismus. There’s no doubt that the  bevacizumab treatment is less stressful to the infant than laser. It’s a far  more elegant from a pathophysiology standpoint, a simpler technique, and a far  more efficient method of care. But, we don’t know the systemic risks of this  medicine, and we don’t know the risks of injection in a small infant whose pars  plana has not developed,” he said.

According to Dr. Barañano, there is a clear need for randomized,  prospective data to guide this decision. In 2010, Mintz-Hittner and colleagues  completed a randomized, prospective, multicenter trial (BEAT-ROP) of 150  infants that compared bevacizumab injection (0.75 mg) with laser treatment for  posterior disease.

The unusual primary outcome, investigator-determined need to  re-treat for “recurrence” of neovascularization, makes it difficult to draw  clinically useful conclusions.

Data showed that re-treatment rates were lower for bevacizumab, at  least over the relatively short follow-up of the trial. Four percent of infants  assigned to receive bevacizumab were re-treated, whereas 22% of infants treated  with laser received further laser treatment. When analyzed by zone, the  difference was statistically significant for zone 1 but not zone 2.

There were a few notable caveats, Dr. Barañano said.

“First, these outcomes were unusual in that they were not looking  at the anatomy of the eye or the visual outcome. They simply looked at the need  to re-treat. The timing of re-treatment of the two therapies varied and many of  the bevacizumab re-treatments occurred toward the end of the follow-up. The  relatively high re-treatment rate [with] laser suggests incomplete peripheral  ablation. This is common in posterior disease. A second session of laser  [treatment] is often employed after regression of the tunica vasculosa and  neovascularization allows for better visualization. This is better thought of  as a staged procedure rather than ‘treatment failure.’ In addition, the  decision to re-treat was made by the unmasked investigators. Finally, the trial  was not designed to assess safety,” he explained.

Currently, researchers are preparing to start a separate  randomized, prospective, multi-centered trial that will look at type 1  pre-threshold disease randomly assigned to two doses of bevacizumab versus  laser treatment. Outcomes will consist of Teller acuity at 1 year, retinal  structure, and developmental scores.

“When considering bevacizumab for ROP, it’s important to weigh the  risks and benefits very carefully. If I think there’s a chance that the child  can get vision without bevacizumab, I think laser is the right choice in 2011.  I do use [bevacizumab] occasionally as adjunct therapy in vascularly active  eyes that require surgery, and I think it’s appropriate as well for very  posterior disease that will not do well with laser. But these children must be  monitored closely after injection, and prompt vitreoretinal intervention should  be available in case contracture leads to retinal detachment,” concluded Dr.  Barañano.

Once these children receive intravitreal bevacizumab, they must be  followed closely for a much longer period than conventionally treated  children. The medicine can wear off. The BEAT-ROP study reported an average  re-treatment interval of 19.2 ± 8.6 weeks. Thus, in contrast to  conventionally managed infants, a significant fraction of infants treated with  bevacizumab appear to develop recurrence of active neovascularization after 60  weeks adjusted gestational age.

Dr. Barañano did not indicate any financial interest in this  topic.

Chow LC, Wright KW, Sola A. Can changes in  clinical practice decrease the incidence of severe retinopathy of prematurity  in very low birth weight infants? 

Mintz-Hittner HA. Avastin as monotherapy for  retinopathy of prematurity. 

Sears JE, Pietz J, Sonnie C, Dolcini D, Hoppe G.  A change in oxygen supplementation can decrease the incidence of retinopathy of  prematurity. 

Wright KW, Sami D, Thompson L, Ramanathan R,  Joseph R, Farzavandi S. A physiologic reduced oxygen protocol decreases the  incidence of threshold retinopathy of prematurity. 

The burden of retinopathy of prematurity (ROP) is great, and researchers are still working to find the most effective and safest treatments, said David Barañano, MD, PhD, at the 24th annual Current Concepts in Ophthalmology meeting.

Still working to solve the ROP puzzle

"The burden of uveitic CME is quite considerable. More than 30% of all patients with uveitis will develop CME, and it is a leading cause of loss of vision and blindness in these patients. Unlike some of the other causes of decreased vision in uveitis, such as cataracts, vitreous debris, or epiretinal membranes, the loss of vision here may not be reversible if the edema isn't cleared in a certain amount of time," said Dr. Butler, assistant professor of Ophthalmology, Johns Hopkins University School of Medicine, Wilmer Eye Institute, Baltimore. 

Interferon alpha is a species-specific cytokine produced by all cells in the body but predominantly by WBC. It has antiviral, antiproliferative, and immunomodulatory activity. The FDA has approved interferon alpha-2b for chronic hepatitis, leukemia and lymphomas, and solid tumors such as melanoma. Its use in patients with CME is currently off-label. 

Early success of interferon alpha in ocular inflammatory disease was demonstrated in patients with Behçet's disease complicated by sight-threatening posterior or panuveitis.

  Fifty patients were treated and had a 92% response rate, with significant improvements in mean visual acuity by week 24 of treatment. In this study, 58 eyes were affected by CME, and there was 100% resolution in these eyes, Dr. Butler explained. 

More recently, other researchers have looked at dose-escalating forms of interferon regimens to minimize the side effects of interferon alpha when treating refractory Behçet's uveitis.

  They found low-dose and dose-escalating interferon alfa-2a therapy similarly effective, with a 95% response rate in 37 patients. 

Another study was done in patients with noninfectious severe posterior uveitis and panuveitis of various etiologies (i.e., not solely Behçet's disease).

  Results showed an 83% response rate to therapy with interferon alpha in 12 patients. In the 14 eyes with CME included in this study, there was also 100% resolution. Side effects were common, however. 

A pilot study was done in 15 eyes in eight patients with non-Behçet's uveitic CME.

  Thirteen of these eyes had a response to systemic interferon alfa-2a with 100% resolution within 2 to 4 weeks. In two patients with non-response or a lost response, antibodies against interferon were present initially or had developed during the study. Of the 11 eyes that continued to be treated over 6 months, the central macular thickness changed from 551 to 143 µm, and mean BCVA (logMAR) improved from +0.80 to +0.42. 

  researchers conducted an interventional case series in 24 consecutive patients (40 eyes) for a mean duration of 36 months. Their results were similar, with 62.5% of patients having 100% response and another 25% meeting their strict "partly effective" criteria. 

Using interferon alpha-2b systemically for the treatment of refractory uveitic cystoid macular edema may be helpful in carefully selected patients.

Agent useful for uveitic cystoid macular edema

-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.