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ARVO: Wavefront Technology e altre nuove ricerche sul KC 
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Iscritto il: lunedì 3 gennaio 2005, 15:06
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Messaggio ARVO: Wavefront Technology e altre nuove ricerche sul KC
ARVO Meeting 1-5 Maggio 2005

Wavefront Technology and KC

Two research groups are working on a soft contact lens custom design using
wavefront technology.

One researcher is exploring wavefront technology to determine the visual
benefit of correcting high order aberration for high and low contrast visual
acuity (VA) in keratoconus. The higher the order of aberration that can be
corrected the sharper the image.

The other group is looking at the dynamic movement of customized contact
lens after blinking. This is one of the factors that reduces visual benefit
of correcting higher order aberrations in the eye. The goal of this study is
to theoretically investigate the feasibility of improving vision with
customized contact lenses in KC eyes when dynamic decentration and rotation
of the customized contact lens are taken into account.

Correcting higher order aberrations provides a larger visual benefit in KC
eyes than in normal eyes. Their calculations demonstrate that correcting
higher order aberration with customized optics improves the retinal image
quality even with the dynamic movement of customized contact lens although
actual perceived vision improvement needs to be evaluated.

Both studies are in the THEORETICAL stage, however these custom lathed soft
lenses corrected by wavefront technology are in the future for KC.


Thursday was KC Day at ARVO, 25 posters were presented covering topics from
genetics to changes in curvature over time. Here is a summary of the info

In genetics - It has long been known that there is no simple Mandelian
pattern of inheritence in KC.It is mostly sporadic The mode of inheritance
is difficult to establish as the disease shows variable expressivity. One
group studied 148 individuals from 22 multiplex families in Ecuador with
KC. Showed no linkage to any of the previously defined KC Loci. A genome
wide scan is in progress. Other groups are exploring various
will continue in this area for some time.

Quality if vision post DLK and PK were compared and no significant
difference in contrast sensitivity and HOA were found.

From the CLEK Group:
Prediction of Vision loss: they found that over the
study period 1in 5 patients experienced a substantial reduction in visual
performance in at least one eye over the 8 yr period. Predictors for a pt
to experience 10 letter (2line) reduction in vision include initial best
corected visdion, Steeper corneal curvature, and Voigts striae

Longitudinal changes in corea curvature - CLEK subjects exhibited a slow bu
clear increase in corneal curvature during the study period of 1.44 to 3 D
Younger age and poorer HC (high contrast )manifest refraction visual acuity
at baseline predicted the rate of change in corneal curvature.

The group at Wills has developed a new device to measure IOP in KC,PMD and
post transplant eyes. Dymamic Contour Tonometer (DCT) will measure IOP
regardless of corneal thickness. KC and PMD usually show low IOP, glaucoma
may be undiagnosed in this population.

Two groups presented information abot Riboflavin and UVA - this first
investigated the depth of stiffening of the cornea using pig eyes. They
found the stiffening in the 200um of the anterior cornea but also in the
deeper levels- the next 200um. However, 65% of the UVA is absorbed in the
first 200um, and only 25% in the deeped 200um. Showing that the deeper
structures and especially the endothelium are not affected.

The other group reviewed human cases and determined in their study that of
27 eyes w/ mod to severe KC (>K48) topographies stabilized over 12-18 mo of
the study. And concluded that Ribo/UVA may offer a promise of stabilizing
of progression of KC by decreasing corneal elastisity.Their work confirms
that of Wloensak: Slows or halts progression and improved UVA They found no
changes in corneal or lenticular clarity, IOP or endothelial cell count. No
adverse outcomes in the 12-18 mos follow up. They suggest this might be a
potentioal pretreatment for PK and may allow surface eximer ablation
otherwise contraindicated in KC.

Two groups are studying wavefront tecnology to determine if this technology
can be applied to custom lathed soft lenses. One group is looking to
correct higher order aberrations for better contrast senssitivity in these
lenses, the other group is working to find means of creating a customized
lens that will correct the vision, but also move on the KC eye.

Lots being done in KC research, lots to follow...and lots to look forward

Cathy Warren

PS: Per chi vuole tentare di capirci qualcosa.. la mezza-traduzione di Zio Google: ... uage_tools

sabato 7 maggio 2005, 14:09
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Iscritto il: lunedì 3 gennaio 2005, 15:06
Messaggi: 2109
Località: Napoli
-More news from the ARVO conference:

Potential new technique for corneal transplant surgery: One research group presented information about the IntraLase laser and its use in corneal transplant surgery. The work done in the laboratory showed that corneas
that underwent the procedure with IntraLase tended to show less induced
astigmatism when compared with the traditional transplant group. After the
laser-based transplant, suture removal may be sooner and the repaired area
may be stronger than conventional transplants. Clinical trials (on humans)
has not yet begun.

martedì 10 maggio 2005, 23:50
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