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World blindness effort needed
The World Cornea Congress met for the first time in conjunction with ASCRS.
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WASHINGTON – Ophthalmologists and primary care physicians must actively fight blindness worldwide by thinking globally but acting locally, urged Rubens Belfort Jr., MD, PhD, MBA.
Dr. Belfort was a keynote speaker at the World Cornea Congress, held here in conjunction with the American Society of Cataract and Refractive Surgery meeting.
Many international organizations are involved in the fight against blindness, he said, including the World Health Organization and the International Council of Ophthalmology.
One of the most important initiatives in the effort to prevent blindness is Vision 2020: The Right to Sight, Dr. Belfort said. The goal of Vision 2020 is to eradicate preventable blindness around the world by the year 2020.
“It is very important that we all follow the same strategy in order to achieve the same goals,” he said.
There are nearly 50,000 blind people in Brazil and 200,000 in all of Latin America, Dr. Belfort said.
“If information is power and information is a tool, it is time to start acting,” he said. “There are too many retrospective studies telling us what we already know.”
Diseases such as trachoma, measles and onchocerciasis globally cause the most cases of corneal blindness, Dr. Belfort explained.
Areas of the world that do not have enough ophthalmologists to diagnose and treat patients’ ocular diseases should encourage primary care physicians to pay close attention to ocular health and nutritional deficiencies, he said.
Corneal blindness in children is particularly a high priority, Dr. Belfort said.
“Train the general practitioners and nurses to identify patients who need corneal care,” he said.
He added that physicians should get involved socially and politically. “Help society remove the barriers to allow patients to see us,” he said.
Because of insufficient numbers of surgeons, a lack of professional eye banking and high costs of viable corneal tissue, corneal grafts are not an option in many countries, Dr. Belfort said.
“The medicine of 1970 is still not available for most of the world population,” he said. “We are more and more practicing ‘boutique ophthalmology’ and practicing ophthalmology for very rich people, very expensive ophthalmology, … but we should never forget the 95% of the population of the world that will never have access to it.”
Despite the graveness of the global situation, Dr. Belfort said he is optimistic that change is possible.
“We have to be active to understand blindness in undeveloped parts of the world as well as developed parts of the world,” he said.
Limbal stem cell replacement
Creating a good postoperative microenvironment for patients who have undergone autologous fibrin-cultured limbal stem cell replacement can be the key to successful long-term results, according to Elisabetta Bohm, MD.
Dr. Bohm presented preliminary results of a 2002 study of eight patients who had received such implants.
“We can conclude that this technique is very safe. … It is fully standardized, and the availability of a second cell culture is a great additional chance we can offer to the patient,” Dr. Bohm said. “This positive aspect compensates for the downside of this technique. It is currently a high cost.”
Five patients in the study received fresh implants and three received frozen implants, Dr. Bohm said.
All of the patients had unilateral burns and severe unilateral limbal deficiencies. Excluded from the study were patients who had other impairments such as inflammation.
“The graft has to be applied on a small surface and under the conjunctival pocket in order to keep it in place without any kind of sutures on the cells,” Dr. Bohm explained.
Postoperative therapy includes preservative-free antibiotics, steroids and lubricants, she said.
“Our latest concerns in the first follow-up have been hemorrhages, thickness and patient compliance,” she said.
A “good microenvironment” is important during recovery, Dr. Bohm said.
“We have, on the 10th day postop, a complete epithelium; that is why our current target is to prevent hemorrhages and to be in the best possible environments for the cells to let them settle down,” she said.
Tear film and acuity
To assess a patient’s functional visual acuity, the acuity should be measured after the patient’s eyes have been open for 30 seconds, according to Kazuo Tsubota, MD.
Dr. Tsubota and colleagues found that visual acuity measurements are more true-to-life when tests are performed with the patient’s eyes held open for a period of time, rather than allowing the patients to blink at will, he told attendees.
Most patients can see well just after they blink and the tear film refreshes, he explained, but in real-life situations, such as when patients are staring at computers, they may experience more symptoms of dry eye.
Factors that contribute to dry eye include a decrease in tear production, inflammation, unstable tear film and a decreased rate of blinking, he said.
“Stable tear film is essential,” Dr. Tsubota said. “Unstable tear film can decrease the function of the visual acuity and can be the primary target for stabilizing dry eye.”
Artificial cornea improving
With an “evolving surgical technique” and an increasing understanding of risk factors for complications, investigators are seeing improving results with the AlphaCor artificial cornea, according to R. Doyle Stulting, MD.
Dr. Stulting reported results to date with the AlphaCor implant. The device, developed in Australia, was approved for use in the United States in 2002. Since the U.S. approval, cases here account for 59% of the total of 239 implants by 69 surgeons, Dr. Stulting said. Follow-up in these eyes ranges from 1 month to 6 years.
The AlphaCor, developed by Argus Biomedical, is distributed in the United States by CooperVision Surgical. The 7-mm-diameter, one-piece device has a central transparent optic surrounded by a biointegratable skirt. It is used in patients who are considered too high-risk for a corneal transplant, Dr. Stulting said. Patients receiving the implant have had as many as 13 previous failed grafts, he said.
Preoperative best corrected visual acuity ranged from light perception to 20/200, Dr. Stulting said, and postop BCVA ranged from light perception to 20/20, with a mean gain of 2 lines of vision.
Increasing experience with the implant – now up to “251 patient-years,” according to Dr. Stulting – has resulted in improved results and a better understanding of risk factors, he said. Corneal melting, which in early trials occurred in as many as 83% of eyes, is now experienced in only about 12% of cases, he said. Retroprosthetic membranes, which were seen in 13.5% of cases, have been found to be associated with race, hypertension and diabetes mellitus. Procedures to prevent postop complications, such as the use of soft contact lenses, have also been identified with increasing experience, Dr. Stulting said.
Intacs for keratoconus
Using a single intrastromal corneal ring segment instead of the standard two to manage keratoconus gives patients less glare and “dramatic” improvement in BCVA, said Antonio Marinho, MD.
Dr. Marinho said he began inserting only one segment of Addition Technology’s Intacs instead of the standard two segments in 2003 in selected patients with keratoconus. To implant Intacs in patients with keratoconus, Dr. Marinho said, he makes a temporal incision and inserts the segment into the inferior cornea, over the steepest meridian.
“We think that using the thickest ring in all cases upon the steepest part of the cornea will have the greatest effect without the need of the second ring,” he said.
A second ring can be inserted if the upper cornea is steep as well, he said.
Reporting on 15 eyes of 12 patients who were followed from 3 to 24 months, Dr. Marinho said BCVA remained the same or improved up to seven lines in all patients.
Most eyes showed a gain of five lines or more in BCVA, he said.
As with other published studies of Intacs for keratoconus, Dr. Marinho said, he noted no correlation between corneal curvature changes and postop refraction or BCVA.
“Trying to do a nomogram in patients with keratoconus is of no use,” Dr. Marinho said.
In his study, he used the 0.45-mm Intacs size in every patient, but he got vastly different results from patient to patient. Because Intacs is designed to be centered on the cornea, he said, treating asymmetrical keratoconus with the devices yields variable visual results.
In his study, nine of 15 eyes had “very good” centration, which explained the excellent results in those patients, he said.
Intacs for post-LASIK ectasia
Implanting intrastromal corneal ring segments into the stroma of patients with LASIK-induced ectasia can stabilize the cornea and may slow the progression of the ectasia, said Michael B. Brenner, MD.
“Deep insertion of intrastromal corneal segments into the corneas of patients with ectasia reduces corneal toricity and improves vision at variable focal lengths,” Dr. Brenner said. “Hopefully, over time, we can prove that intrastromal segments also prevent disease progression.”
In a study, Dr. Brenner implanted 2 asymmetric corneal ring segments into the corneas of refractive patients with corneal ectasia. By 1 year postop, sphericity was reduced by 3 D in most of the patients, he said.
“The reduction in sphericity occurred immediately, minutes after surgery, and remained consistent up to a year,” Dr. Brenner noted.
With the increase in volume of refractive surgery in the United States, Dr. Brenner said, it is important for surgeons to determine ways of effectively treating refractive complications such as ectasia, which, he noted, “are sure to rise with the influx of refractive patients.”
More from the WCC
Other reports from the World Cornea Congress can be found in our Spotlight on Ocular Infection in this issue.