David Spalton MD, FRCS
One of the highlights of this year's ESCRS Winter Meeting will be the HSIORS Charles Kelman Award lecture, which will be delivered by David Spalton MD, FRCS, UK, during the Welcome Ceremony in Hall Trianti on Friday February 15th.
Professor Spalton's lecture on "Life behind the lens" will concern the unsolved problem of long-term posterior capsule opacification (PCO) prevention.
"Most of my clinical research concerned PCO, its aetiology, its detection and potential means of prevention. In the early 1990s, we developed a method at St. Thomas's Hospital for detecting and quantifying PCO. It involved designing a special state-of-the-art retroillumination camera and the adaptation of a software program used for military imaging analysis," said Prof Spalton.
Prof Spalton said that prior to that, people tried to segment and quantify retroillumination images on the basis of intensity thresholds.
"That doesn't work well with PCO so we adapted a very sophisticated software program developed for the RAF to identifying potential military targets to segment and quantify PCO. The software is based on texture analysis, which compares the variation in intensity between adjacent pixels," he said.
INVESTIGATION AND STUDIES
Prof Spalton said that very serendipitously, at that time Alcon realised that eyes with Acrysof IOLs had low levels of PCO, which was a total surprise. Alcon asked Prof Spalton to investigate and a study that compared the PCO outcomes in eyes with PMMA and Acrysof IOLs confirmed that there was less PCO with the Acrysof lens. Later research by Okihiro Nishi and others demonstrated that it was the IOL’s square-edge that reduced PCO rather than the lens material. However, with longer follow-up it became apparent that square-edged lenses only delay, but don't prevent, PCO.
"Therefore we have yet to find a long-term solution to PCO prevention," said Prof Spalton. "There are several strategies that are currently under investigation. One of them is Burkhard Dick MD’s technique of using a femtosecond laser to perform a posterior capsulorhexis at the end of a cataract procedure period. Another is Hoya's IOLs, which have posterior surfaces treated with ozone, which increases the adhesivity of the lens to the capsular tissue and hopefully prevent the cells from proliferating," he said.
In his lecture, Prof Spalton will also discuss a third approach, which is a lens that keeps the capsular bag open. "There is a lot of evidence that preventing the anterior and posterior capsule from coming into contact allows the aqueous to irrigate the capsular bag and wash out the growth factors and cytokines, and that seems to stop PCO from forming. The open-bag concept is very attractive because, in theory, that could leave you with a flexible bag for an accommodative lens," he said.
"Each of these approaches has their own theoretical advantages and disadvantages, which I will discuss in my lecture. But only long-term follow-up can determine if they will provide long-term prevention of PCO," said Prof Spalton.
