This article is more than 5 years old. Information may no longer be current.
'Supervision' effects may not be permanent, says expert
Click Here to Manage Email Alerts
AMSTERDAM -- For some patients, "supervision" may not be long-lasting, according to an expert in optics and vision who spoke here at the XIX Congress of the ESCRS.
Changes in the human lens, increasingly toward positive spherical aberrqation, eventually lead to an optical lens-cornea mismatch, said Jack Holladay, MD.
"You're going downhill from the day you do it," Dr. Holladay said. The change must be anticipated, he added.
In young eyes, the natural lens — which has negative spherical aberration — is matched perfectly to the positive spherical aberration of the cornea. The shift toward positive spherical aberration, occurring around age 40, "in combination with the remaining cornea, results in terrible optical performance," Dr. Holladay said. As long as the retina is healthy, the key components of a high performance visual system are lens and cornea, Dr. Holladay continued.
A prolate cornea matched to a prolate intraocular lens with slightly negative aberration will result in very high performance visual systems, he stated. It will be perfectly matched to the positive aberration of the prolate cornea, he said.
To that end, Pharmacia Corp. is developing an IOL with negative spherical aberration and prolate design. Laser manufacturers are busy developing treatments that keep the cornea's prolate shape, Dr. Holladay pointed out. But unlike the natural lens, the cornea's optical quality remains consistent throughout life, he added.
"The reasons for having a reduction in the performance of the optical system is due to the crystalline lens' decreasing performance at higher-order aberrations, but the positive spherical aberration is most dramatic, and the one that we can correct," Dr. Holladay said.