Pinhole Lens Restores Sight for Patients With Scarred Corneas

Pinhole Lens Restores Sight for Patients With Scarred Corneas

For people whose corneas were reshaped by refractive surgery or scared by disease, cataract surgery has long been a gamble. A new study suggests that a pinhole lens can improve the odds of achieving clear vision.<_o3a_p>

NEW ORLEANS - A generation of Americans paid to have their nearsightedness corrected with a scalpel or a laser. Now many of them are reaching the age of cataracts, and they are discovering that the corneas they once had reshaped no longer bend light cleanly. For these patients, the standard replacement lenses implanted during cataract surgery often cannot deliver the crisp vision they expect.<_o3a_p>

A study presented this week at the 130th annual meeting of the American Academy of Ophthalmology suggests that one implant may succeed where others fall short. In 25 eyes with prior corneal surgery or corneal disease, a small-aperture lens called the IC-8 Apthera gave every eye corrected distance vision of 20/32 or better. Most of the patients could also see well at arm's length and up close.<_o3a_p>

"In the right patients, these lenses can improve vision in ways not available with any other lens in the U.S. market," said ophthalmologist and lead researcher, Karl Stonecipher, MD.<_o3a_p>

How a tiny ring sharpens blurry vision<_o3a_p>

The principle is the same one that makes squinting work. The IC-8 Apthera carries a small opaque ring that lets light through only a narrow central opening. Stray rays scattered by an irregular cornea are blocked before they reach the retina, and the eye gains a deeper range of focus.<_o3a_p>

That matters most for eyes with high "higher-order aberrations," the complex distortions that eyeglasses cannot fix. In the study, the corneas themselves were badly distorted, measuring 1.62 microns of higher-order aberration across a 6-millimeter zone. Measured through the whole eye after surgery, the figure was 0.07 microns.<_o3a_p>

What the study found<_o3a_p>

The researchers reviewed the records of 25 eyes that received the lens during cataract surgery. About half, 52 percent, had undergone LASIK. Another 36 percent had radial keratotomy, the incision-based procedure popular in the 1980s. The rest had keratoconus, a progressive thinning of the cornea, or ectasia after PRK laser surgery.<_o3a_p>

After surgery, 80 percent of the eyes saw 20/32 or better at distance without glasses. With distance correction in place, 88 percent reached 20/40 or better at near and intermediate range, the distances used for reading and screens. On average, the eyes landed within about a third of a diopter of their refractive target.<_o3a_p>

"I continue to be surprised by how functional these patients become, especially those with dramatic higher-order aberrations and fluctuating vision," Dr. Stonecipher said. "They comment that the quality and quantity of their vision is finally back."<_o3a_p>

Not for everyone<_o3a_p>

The lens is not without trade-offs. Because it admits less light, some patients notice that the world looks dimmer. Dr. Stonecipher said two patients from the trial, both engineers, report dimming in the treated eye, as do two patients treated since approval. All four still have their lenses, and the two trial patients see 20/20 at distance, intermediate and near.<_o3a_p>

The study also has limits. It looked back at a small number of eyes from one surgeon's practice, with no comparison group, and larger prospective studies will be needed to confirm the findings.<_o3a_p>

Dr. Stonecipher's central message to fellow surgeons is that careful screening is essential. He uses the iTrace aberrometer and OPD3 optical analysis software, which can simulate whether the small aperture will actually improve a given patient's vision before surgery.<_o3a_p>

Over the past year, he has added an artificial intelligence tool to that process. Patients answer a guided set of questions about their work, hobbies and visual complaints, and the tool narrows in on their needs and suggests educational videos. He now uses it with all patients considering premium lenses. "It has been a game changer," he said.<_o3a_p>

What comes next<_o3a_p>

The next phase of the research looks beyond eye charts. Dr. Stonecipher is working with a high school student interested in psychology to develop a happiness survey for these patients. Results are not yet available.<_o3a_p>

For patients who have spent years with blurry, shifting vision, the question may finally be less about how well they read the chart than about how they feel about what they see.<_o3a_p>

About the American Academy of Ophthalmology<_o3a_p>

The American Academy of Ophthalmology is the world's largest association of eye physicians and surgeons. A global community of 32,000 medical doctors, we protect sight and empower lives by setting the standards for ophthalmic education and advocating for our patients and the public. We innovate and support research to advance our profession and to ensure the delivery of the highest-quality eye care. Our EyeSmart® program provides the public with the most trusted information about eye health. For more information, visit aao.org.<_o3a_p>

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