Experts address five common ocular conditions that affect children

Pediatric ophthalmologists use different diagnostic methods and treatment options to restore vision in children.

With new research and studies looking at various aspects of pediatric ocular diseases and issues, physicians are striving for the most effective treatments possible to reduce the risk of childhood blindness and improve visual acuity.

Amblyopia, strabismus, congenital cataracts, childhood glaucoma and retinopathy of prematurity (ROP) are five of the most common conditions treated by pediatric ophthalmologists. Several experts spoke with Ocular Surgery News about the latest information in care and research of these pediatric ocular issues.

Amblyopia

Amblyopia and strabismus occur in 2% to 5% of children in the United States, said Leonard Nelson, MD, MBA, co-editor of the Journal of Pediatric Ophthalmology & Strabismus.

Despite the prevalence of the condition, detecting amblyopia is not always easy, he said. Whereas strabismus often presents with an obvious misalignment of the eyes, amblyopia does not have any symptoms.

“A child doesn’t complain that they don’t see well. Just like if you have high blood pressure, you wouldn’t realize you had it because there are no symptoms. So the only way that you can pick up an asymptomatic condition is to screen for it,” he said.

Children with decreased visual acuity are typically referred to a pediatric ophthalmologist by their schools or pediatricians. In making a diagnosis, pediatric ophthalmologists subject their patients to fixation pattern tests and cycloplegic refraction, Dr. Nelson said.

Leonard Nelson

“If there’s a difference between the two eyes in terms of a refraction, where one eye is more farsighted or nearsighted or astigmatic than the other eye, then you have to make the assumption that you are probably dealing with a child with amblyopia,” he said.

Before treating amblyopia, physicians should address any underlying issues, such as strabismus or refractive error, which could compound the problem, Dr. Nelson said. Once amblyopia treatment begins, the physician’s main goal should be to force the weaker eye to see better.

Treating amblyopia early is critical for ensuring long-term visual health. He cited research by David Hubel and Torsten Wiesel, two Harvard physiologists who won the 1981 Nobel Prize for defining a “sensitive period” of visual development in the brain, among other discoveries.

“[They found that] when an eye was deprived of fixation of stimulation, there were changes in the brain that occurred. And if it was long enough, [those changes] would be permanent. So in treating amblyopia, you have to force the visual system of the brain to include,” Dr. Nelson said.

Pediatric ophthalmologists typically occlude the stronger eye to force the weaker eye to function, he said, adding that patching is the “mainstay” of occlusion methods.

Although patching has been used for several decades, research continues to refine the ways in which ophthalmologists prescribe this basic method of occlusion.

A study conducted by the Pediatric Eye Disease Investigator Group (PEDIG), a network of community- and university-based eye care providers, showed that patches were effective for severe amblyopia when worn for as little as 6 hours per day. A second study by the PEDIG showed patching had a beneficial effect in 7- to 18-year-olds who were often thought to be beyond the age of amblyopia treatment.

Kenneth P. Cheng

OSN Pediatrics/Strabismus Section Member Kenneth P. Cheng, MD, added that ongoing research is evaluating systemic medications for making older patients, including adults, more amenable to amblyopia treatment.

Other PEDIG trials confirmed the efficacy of atropine drops for blurring the stronger eye, Dr. Cheng said. As a proxy for an eye patch, which can carry a social stigma, atropine drops have been shown to increase patient cooperation, he said.

“But there are a lot of questions about [atropine],” Dr. Nelson said. “Certainly in a child who has dense amblyopia, with very poor vision, giving atropine is not going to do very much. Because what atropine does is just blur the vision up close. So if you have a child of any age who’s not focusing up close all the time, then they’re going to use that eye to see with and not the other eye.”

Dr. Nelson added that the lack of vision screening programs in United States, especially in disadvantaged areas, is the most pressing concern in amblyopia treatment.

Earlier this year, the American Academy of Ophthalmology joined with the American Optometric Association to draft legislation for funding eye exams on a state-by-state basis, with priority given to children younger than 9 years. The bill was introduced in the House of Representatives in January and the Senate in April. A House committee recently approved the bill (see related article).

Strabismus

Strabismus usually presents with an obvious misalignment of the eyes. If glasses cannot fix the problem, then surgery is indicated, Dr. Nelson said.

Although there are many variations on surgical intervention, the ultimate goal of any strabismus surgery is to get the binocular system of the eyes to work together. Whereas most surgery involves repositioning muscles, “strabismus is a problem not of a muscle,” he said.

“It’s a problem of the brain and eyes not working together. For instance, if you’re right-handed and you can’t write with your left hand, it’s not because your left hand is abnormal. It’s because the brain has decided you’re using your right-handed,” Dr. Nelson said.

There are certain strabismus cases that stem from paralyzed, weak or overacting muscles, he said, but most often the condition is tied to an abnormal binocular system.

“If you have a young child that is born or developed congenital esotropia during the first 6 months of life, it’s been well shown that their binocular system has not developed normally. And you want to recreate binocular vision and develop it so that the same stimulation in each eye develops, and they develop some degree of binocular cooperation,” he said.

The surgical techniques in strabismus surgery have undergone few changes over the years. There have been refinements in sutures and increasingly larger movements of muscles, but these changes are “minor variations,” Dr. Nelson said.

“There are some different techniques, but the real changes in ophthalmology have not occurred in pediatric ophthalmology,” he said. “Most of medicine is about the anatomy. By taking a cataract out, you take out a cloudiness of the lens. That’s an anatomic problem, but strabismus is not an anatomic problem. You’re operating on muscles that are not abnormal. You’re operating to realign the eyes so the brain and eyes work together. It’s a very different approach to the problem.”

Congenital cataracts

OSN Pediatrics/Strabismus Section Member Anthony P. Johnson, MD, FACS, said one in 250 children is born with congenital cataracts. It has been determined that congenital cataracts can be transmitted in an autosomal dominant, recessive or X-linked pattern; they can also be linked to abnormalities in chromosome 1, 2, 13, 16, 17, 18 or 21, he said.

Congenital cataracts cause almost 10% of all visual loss in children worldwide. In addition, children with unilateral cataract can be predisposed to amblyopia. Cataracts can present with strabismus, which can assist in diagnosis, and they can also present in a lack of visual attentiveness, a “white pupil” or decreased red reflex identified by the pediatrician or family physician, Dr. Johnson said.

Rudolph S. Wagner

Treatment in the field has been advancing rapidly, and some physicians are implanting IOLs in infants at earlier ages than in the past, he said. The Amblyopia Treatment Trial, an ongoing, multicenter study, is being conducted to examine the effectiveness of early IOL placement vs. contact lens use in the first 2 years of life. The Infant Aphakia Treatment Study is also examining the subject. Both studies are sponsored by the National Institutes of Health.

“If significant enough, the congenital cataract requires surgical removal and frequently an IOL is placed,” Dr. Johnson said. “They still require close follow-up and amblyopia treatment.”

OSN Pediatrics/Strabismus Section Member Rudolph S. Wagner, MD, said IOL implantation in infants is still being investigated, and many physicians are awaiting study results before pursuing IOL implantation.

“It is my impression that the babies receiving implants have a higher complication rate regarding glaucoma and secondary membranes and often require an additional surgical procedure,” Dr. Wagner said. “As of today, many ophthalmologists would not implant an IOL in a baby less than 3 months of age and still rely on contact lenses for correction of aphakia. Positive published results from the Infant Aphakia Treatment Study may change their thinking.”

Childhood glaucoma

According to Dr. Johnson, primary congenital glaucoma occurs in about one child in 10,000. It is less common than primary adult glaucoma, but it is still an important pediatric ophthalmic issue.

Classic presenting symptoms of childhood glaucoma are photophobia, epiphora and blepharospasm. Examinations should measure IOP, horizontal corneal diameter and axial length, and gonioscopy and retinoscopy should also be performed, he said.

“Patients often have an enlarged horizontal corneal diameter, Haab’s striae and even a cloudy cornea from corneal edema,” Dr. Johnson said. “Pediatric glaucoma is almost always a surgical disease, but patients can also require long-term glaucoma meds as well. They often have unusual refractive errors and frequently have amblyopia that requires careful management.”

There is new and exciting research that is examining the use of clinical genetics to assist in treating glaucoma, Dr. Johnson said. Dr. Wagner said more advanced surgical procedures, such as valves to control IOP, could be on the horizon. Pediatric glaucoma could also become more of a specialty within pediatric ophthalmology.

“These newer techniques are most often performed by glaucoma specialists,” Dr. Wagner said.

Retinopathy of prematurity

As survival rates for premature babies improve, the incidences of ROP are also increasing. About 7% of babies with birth weights less than 1,251 g reach threshold ROP and require treatment, and 85% of babies with ROP have spontaneous regression, Dr. Johnson said. The main risk factors are low birth, how early the baby was born and how sick the baby is with other comorbidities.

ROP treatment is performed with laser or cryotherapy of the ischemic retina. Laser is most frequently performed, but cryotherapy can be required if there is poor visibility of the retina, Dr. Johnson said.

“The main issue is very careful monitoring of these babies, as their status can change relatively quickly,” he said.

Robert S. Gold, MD, OSN Pediatrics/Strabismus Section Editor, said ROP screening guidelines published in the February 2006 and September 2006 issues of the Journal of Pediatrics updated the standards set earlier for ROP screening and treatment.

“Basically, the familiarity of the pediatric ophthalmologists and the retina specialists with these criteria, as to when to see these babies and when to follow up these babies and then when to recommend treatment for these babies, is critical,” Dr. Gold said.

He said the guidelines discuss numerous issues, including how to involve families in the treatment process, how neonatal intensive care units should establish protocol to use the screening guidelines and follow-up procedures.

“A lot of this was brought about because the retinopathy of prematurity was under the radar for medical legal issues, and so we’re trying to be on the same page for the sole purpose of preserving vision in these little babies,” Dr. Gold said. “As long as we’re all on the same page, the chances of preserving these babies’ vision are much greater.”

For more information:

• Kenneth P. Cheng, MD, can be reached at 1000 Stonewood Drive, Suite 310, Wexford, PA 15090; 724-934-3333; e-mail: kpc123@verizon.net.
• Robert S. Gold, MD, can be reached at 225 W. State Road 434, Suite 111, Longwood, FL 32750; 407-767-6411; fax: 407- 767-8160; e-mail: rsgeye@aol.com.
• Anthony P. Johnson, MD, FACS, can be reached at 601 Halton Road, Greenville, SC 29607; 864-458-7956; fax: 864-458-8390; e-mail: apj@jervey.com.
• Leonard Nelson, MD, MBA, can be reached at Lankenau Hospital, 100 Lancaster Ave., Wynnewood, PA 19096; 610-645-2000.
• Rudolph S. Wagner, MD, can be reached at Children’s Eye Care Center, 495 N. 13th St., Newark, NJ 07107; 973-485-3186; fax: 973-497-5674; e-mail: wagdoc@comcast.net.

• Erin L. Boyle is an OSN Staff Writer who covers all aspects of ophthalmology.
• Andy Moskowitz is an OSN Correspondent based in Collingswood, N.J.