Transcript Effect of an irregular anterior surface on a lamellar

Effect of an irregular anterior
surface on a lamellar femtosecond
laser cut
Robert E. Fintelmann, MD
Michele M. Bloomer, MD
Bennie H. Jeng, MD
Department of Ophthalmology
University of California San Francisco
[email protected]
Authors have no financial interest
Introduction
 First femtosecond laser approved in 2000
to create lamellar cuts for LASIK
 Now being used for
Anterior and posterior lamellar keratoplasty
Customized trephination for penetrating
keratoplasty
Tunnel creation for intracorneal ring
segments
Astigmatic keratotomy
Purpose
 To determine if the femtosecond laser be
used to create reliable cuts under an
irregular corneal surface.
Methods
 Three types of defects created
Rectangle at 210µm
Manual 2.5 mm punch
Manual triangular defect
 Three corneas masked with
hydroxypropylmethylcellulose
 Three corneas without masking agent
 Lamellar cuts created with femtosecond laser
(300µm depth, 9mm Diameter, power 3mJ,
IntraLase, Model FS60, software v 1.12 Abbott
Medical optics, Abbott Park, IL)
 Corneas examined with ocular coherence
tomography (RTVue SD-OCT with CAM-L
lens) (Figure 1)
 All corneas were then fixed in formaldehyde,
cut through the created defect and examined
under the microscope
Figure 1: OCT of Defects
En face OCT of rectangle
Transverse OCT of rectangle
Results
 Femtosecond laser creates a smooth cut
under irregular surfaces (Figure 2)
 Irregularities on the surface can lead to
differences in thickness in the bed (Figure
3)
 No difference in bed appearance between
masked and unmasked corneas
Figure 2: OCT of bed
Bed under rectangle
Bed under punch
Thinning of bed under
defect
Figure 3:
Histopathology of cornea under defect
Thinner bed in
area under
defect
Thicker bed
outside area
of defect
Discussion
 Femtosecond lasers can help changing an
irregular surface into a smooth bed for a
corneal transplant
 Small study size insufficient to quantify
the variability in the beds
 Masking agent does not appear to be
necessary for producing regular beds
 A corneal graft with a regular surface
placed into the now smoother bed may
give a good clinical outcome
References
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