is the clear window to the eye and is the eye’s most powerful
refractive (or light bending)
component. For the best visual acuity to occur,
the cornea must remain clear and also present a spherical surface to the
oncoming rays of light. Unfortunately, not every cornea is spherical
surface similar to that of a basketball
. Rather, some corneas are astigmatic
have a configuration comparable (in the extreme) to that of a football
longitudinally across the length of the ball. Astigmatism can arise after
corneal transplant surgery. Even if the continuous suture has been adjusted
post-operatively, once the suture has been removed, astigmatism can return.
A spherical or non-astigmatic corneal surface bends all rays of light as
they strike the front of the eye to focus on the retina.
If an astigmatic cornea is present, perpendicular planes of light will be
focused differently by the cornea. Only one plane of light will strike the
retina while the other perpendicular plane will be focused either in front or behind the retina. This occurs in the astigmatic cornea because
it has two different curves: a flatter or weaker curve and a steeper or stronger
curve, analogous to the two curves of a football: the steeper curve across the
laces vs. the more gentle (flatter) curve from end to end. The objective of
corneal astigmatic surgery is to transform a football configuration into the
curves of a basketball. The Arcitome is particularly effective in treating
astigmatism following corneal transplant surgery.
The Nidek OPD Wavefront Scan is used to analyze the level of corneal
astigmatism. This device projects a series of concentric rings on the cornea
yielding a large series of data points which are converted into a topographic
The Nidek OPD Map below shows a cornea with astigmatism in a
configuration at an oblique axis.
To correct the astigmatic cornea, relaxing incisions are made across the
steepest axis of the cornea, i.e., across that area of the cornea showing the
bow tie configuration.
Once this has been accomplished, the perpendicular planes of light should
jointly focus on the retina, providing no other refractive component is present.
Also, it has been demonstrated that the most effective incisions should be
curvilinear or arcuate.
The Arcitome, state-of-the-art instrumentation, is used
to make extremely accurate arcuate incisions. The Arcitome has two
diamond blades and each blade
can be adjusted for depth, degrees of arc, and radius of curvature.
Components of the Arcitome System.
Various adjustments can be made to the Arcitome to achieve an excellent
post-operative result. The diamond blades are incorporated into an arcuate
mechanism that allow two very precise inicisional arcs to be made in the
Arcitome is adjusted using the parameters of the
nomogram to treat astigmatism following corneal transplant surgery. A
slightly different nomogram is used for astigmatism not associated with
penetrating keratoplasty, although another option is this instance is the use of
the excimer laser.
The corneal thickness is determined using the Pachymetry Map mode of
The measuring technology of the
BladeScan is used to set the depth of
the Arcitome. Dr. Rubman designed
the integration of the Arcitome with
the BladeScan and has the only unit
in the world capable of performing these measurements.
All the measurements for Arcitome surgery are determined in
advance and the instrument is set prior to the patient entering the operating
room. As a result, the procedure takes a minimum amount of time. After the
cornea has been marked with the 360 degree ruler and the steepest
axis is confirmed with the Ring of Light, the Arcitome is
placed on the anesthetized eye, the diamond blades activated and the arcuate
Dr. Rubman was the first surgeon to acquire and use the
in the NYC Metro area.