1. Comparison of Early Anatomical, Functional and Safety Results of 3 Anterior Lamellar Keratoplasty Techniques
Ramón Naranjo-Tackman,MD
Ilka E. De Obaldía-Faruggia,MD
Cornea and Refractive Surgery Department
Assn. To Prevent Blindness in Mexico
Mexico

2. OBJECTIVES:
To stablish the potential advantages of 3 different techniques for Anterior Lamellar Keratoplasty(ALK):
Microkeratome assisted ALK,
Femtosecond Laser Assisted ALK and
Predescemet big bubble technique,
In terms of anatomical integrity, visual results and endothelial survival.

3. MATERIAL AND METHODS: Patients diagnosed with Keratoconus.
Patients were divided in 3 groups, to determine the differences between 3 different ALK techniques.
Inclusion criteria were:
corneas had to be thinner than 450μ, and thicker than 350μ, with contact lens intolerance
and were assigned to three different groups:
1: Microkeratome assisted ALK, an Amadeus®(Ziemer ophthalmics, Switzerland) microkeratome and artificial anterior chamber, using a 200 or 250μ cutting plate.
2: Femtosecond laser assisted ALK, an Intralase® (AMO-Intralase, California)30KHz FSL was used.
3:Big bubble pre-Descemet's technique. UCVA,BSCVA,K readings, were measured at PreOp. and Mo. 1 and 3. Corneal imaging was done using a Visante® OCT (C. Zeiss, Germany), for contrast sensitivity a CSV-1000 screen was used, and for endothelial evaluation a Topcon® specular non contact microscope was used.All surgeries were done by the same surgeon (RNT)

4. MATERIAL AND METHODS:
Methods:
UCVA,BSCVA,K readings, were measured at PreOp. and Mo. 1 and 3.
Corneal imaging was done using a Visante® OCT (C. Zeiss, Germany),
Contrast sensitivity a CSV-1000 screen was used
For endothelial evaluation a Topcon® specular non contact microscope was used.
All surgeries were done by the same surgeon (RNT)

5. RESULTS
A total of 18 eyes were included, and divided in the 3 groups in equal numbers.
The Mean PreOperative values for all cases were:
UCVA:20/400, BSCVA: 20/70, K:53.2D,
Thickness 412μ,
Contrast sensitivity at 3,6,12,18 were 3,4,4,4 Respectively.
Endothelial cell density was:2456. At Mo. 3, Mean postoperative values were: G 1:UCVA:20/80,BSCVA: 20/50, K’s: 51.2D, Thickness: 510 μ, CV: 3,3,2,3, Endotelial cells: 2107± 283.Mean donor thickness: 250 μ G 2:UCVA:20/80,BSCVA: 20/50, K’s: 49.62D, Thickness: 573 μ, CV: 2,3,2,3, Endothelial cells: 1902± 417. Mean donor thickness 370μ G 3:UCVA:20/70,BSCVA: 20/40, K’s: 50.7D, Thickness: 540 μ, CV: 3,3,3,3, Endotelial cells: 1862± OCT Images disclosed a more anatomical resemblance of the anterior surface of the cornea in group 1.

6. LAMELAR CON BURBUJA Big bubble technique:
Best case of improvement of contrast sensitivity
Pre and postOp Keratometric maps in this case
Confocal image of the posterior donor estroma, showing microfolds.
Although the contrast sensitivity imoproved extremelly well, this case is the exception, not the rule.

7. DISCUSION:
Anterior lamellar keratoplasty, has certain well defined advantages over PK,
Microkeratome lamellar keratoplasties, were the ones that achieved the best anatomical results, in terms of curvature and shape, and less reduction of endothelial cells, no improvement in contrast sensitivity was observed.
Femtosecond assisted lamellar keratoplasty became the most repeteable, and kept a very good endothelial cell count, there was no improve in contrast sensitivy
The 3rd. Group showed only one case with an impressive improvement in contrast sensitivity, but more decrease in the endothelial cell count.

8. CONCLUSIONS
Anterior lamellar keratoplasty, has certain well defined advantages over PK, but has been criticized about the lack of visual quality, and poor contrast sensitivity.
This series, although rather short, tries to define if there are anatomical, functional or safety issues that may have to be considered when deciding an specific technique.
We think that the main factor to consider, is to evaluate endothelial manipulation in the pre-descemet techniques, that may pose a risk for long term graft survival.
Definetively, until we improve the interface that is not natural, and we are creating, this will the factor not allowing us to improve visual quality after the graft.