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New anterior chamber phakic IOL
shows good longterm safety and predictability in high myopia
By
Cheryl Guttman In San Francisco
Clinical results obtained with the angle-supported AcrySof Phakic
ACL for the treatment of high myopia are "outstanding",
reported Michael C. Knorz MD, at the annual ASCRS Symposium on Cataract,
IOL and Refractive Surgery.
The AcrySof Phakic ACL is a foldable, single-piece implant made
from the same hydrophobic acrylic material as the AcrySof pseudophakic
IOL and is implanted similarly through a small incision using the
Monarch II injector. The AcrySof Phakic ACL features a 5.5-mm meniscus
optic, and for the Phase I trial, it was available in three different
lengths – 12.5, 13.0, and 13.5-mm, and in powers to correct
from -8 to -16 D of myopia.
Dr Knorz of Mannheim and Dr Joseph Colin of Bordeaux are the investigators
in the Phase I trial. They implanted 10 eyes, of which nine were
seen at a two-year postoperative visit and six reached the three-year
visit. Two of the latter eyes suffered from progressive myopia and
progressive astigmatism, respectively, thus confounding the visual
function and predictability outcomes.
Overall, however, the AcrySof Phakic ACL has performed impressively
in the analyses of visual acuity, refractive outcomes, and safety,
and patient satisfaction has been high as well, according to Dr
Knorz:
"So far, this phakic IOL has demonstrated benefits for improving
functional uncorrected vision, and as a result of its unique design
and biocompatibility, its safety profile has been very favourable
with no lens-related adverse events, progressive endothelial cell
loss, pupil ovalization, or cataractogenesis. Those positive results
are further enhanced by the ease of folding and insertion of this
lens and we look forward to further studies.
 Data
from the last available visit show UCVA was 20/25 or better in six
eyes and better than 20/20 in three. The BSCVA was better than 20/40
in all eyes and 20/25 or better in eight of the nine. A single patient
seen at two years lost one line in BSCVA. Three eyes gained 1 or
2 lines and the rest had no change.
At one and two years, achieved SE was within 1 D of the attempted
correction in 83% and 86% of eyes, respectively. Of the six eyes
seen at three years, only four (67%) eyes had achieved SE within
1 D of attempted. The percentage of eyes within 0.5 D of intended
SE was 57% at the first year, 71% at two years, and 67% at three
years.
"The refractive predictability results at all visits generally
satisfy the FDA Guidance Document target that requires 75% of eyes
to be within 1 D of the attempted refraction and 50% within 0.5
D. At three years, the study outcome falls short of meeting the
1 D target only because two eyes had progressive refractive changes,"
said Dr Knorz.
Endothelial cell counts are being monitored as part of the safety
evaluation. Those results show a 13.25% loss from preop to six months
that could be attributed to the surgery, but for eyes followed to
two years, mean endothelial cell count between six and 24 months
showed an annualised increase of 1.16%. For the eyes reaching the
three-year follow-up, there was an annualised mean loss of only
about 0.25%.
As part of the safety evaluation, Scheimpflug image analysis is
being performed to measure the vault of the IOL in the anterior
chamber and its distance from both the cornea and the crystalline
lens. Up to three years after implantation, the lens maintained
a safe distance from both the endothelium and the crystalline lens.
Michael C. Knorz,
Professor of Ophthalmology,
Faculty of Clinical Medicine
University Hospital of Mannheim
knorz@eyes.de
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