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Penetrating versus big-bubble deep anterior lamellar keratoplasty for keratoconus in the same patient: a qualitative and quantitative study

Poster Details

First Author: M.Giannico ITALY

Co Author(s):    R. Fasciani   L. Mosca   E. Balestrazzi   A. Caporossi     

Abstract Details


To investigate the safety and efficacy of penetrating keratoplasty (PK) and deep anterior lamellar keratoplasty performed with the 'Big-Bubble' technique (BB-DALK), in the same patient affected by keratoconus. A qualitative and quantitative analysis was performed.


Every surgical procedure and clinical observations were performed at the Ophthalmology Department of the 'A. Gemelli' Polyclinic, Rome, Italy. The corneal transplantation archive of the 'Cornea and Refractive Surgery' Service of the 'A. Gemelli' Polyclinic, including medical records and a digital database, was accurately analyzed to select the 10 patients enrolled in the study.


This prospective comparative case-control series study involved 20 eyes of 10 patients, 7 men and 3 women (mean age: 38.1 years ± 14.0SD), affected by moderate to advanced keratoconus, who underwent PK in one eye (Group A: 10 eyes, mean age at the time of surgery of 34.3 ± 13.3 SD), and BB-DALK in the fellow eye (Group B: 10 eyes, mean age at the time of surgery of 36.4 ± 14.0 SD), between 2004 and 2010. Preoperative quantitative parameters were: uncorrected visual acuity (UCVA); best-spectacle corrected visual acuity (BSCVA); mean spherical refractive equivalent (MSRE); optic pachymetry; topographic corneal power (CP) and topographic astigmatism (TA). Qualitative analysis included: the Pelli-Robson contrast sensitivity test; the ultra structural in vivo confocal microscopy analysis of the grafts; the Visual Functioning Questionnaire VFQ-25, and the 'Visual Subjective Questionnaire' (VSQ), formulated by the authors for the present study. Outcomes of each group were acquired one year after surgery and at the final mean follow-up (Group A: 47.1 months ± 24.9SD; Group B: 21.8 months ± 15.9SD). Repeated-measures analysis of variance (ANOVA) and the paired t test were used for the statistical analysis. A p value less than 0.05 was considered statistically significant.


No significant difference in UCVA (p = 0.364) and BSCVA (p = 0.964) were found one year postoperatively. At the final mean follow-up, UCVA was significantly higher in Group A (p = 0.020), but no significant difference in BSCVA was reported between the two groups (p = 0.050). Both groups showed no significant differences in term of MRSE (p = 0.498; p = 0.449), of CP (p = 0.113; p = 0.117), of TA (p = 0.744; p = 0. 711) at one year and at the final mean follow-up, respectively. A physiological pachymetry was restored: Group A: 525.3μ ± 67.9 SD; Group B: 532.8μ ± 50.5 SD (p =0.641). Final contrast sensitivity was 1.54 log ± 0.21 SD in Group A and 1.57 log ± 0.16 SD in Group B (p = 0.727). In Group B, confocal microscopy evidenced a residual bed thickness of 22.2 μ ± 10.1SD and an interface scattering of 76.6% ± 26.7SD with some hypo reflective striae and hyper reflective dots; stromal alterations and low density of keratocytes in grafts that underwent previous rejection episodes. Most of patients referred a moderate to high visual related quality of life and a satisfactory quality of vision.


To the best of our knowledge, this is the first qualitative analysis of visual related quality of life and of the subjective quality of vision in patients undergoing two techniques of corneal keratoplasty. PK and BB-DALK are safe and effective procedures for the surgical treatment of keratoconus. Lamellar keratoplasty allows to preserve corneal endothelium without any risk of endothelial rejection, despite a longer surgical time. It could represent an appropriate alternative to PK, providing similar BSCVA, refractive and qualitative results, especially for patients who experience medical care with difficulty, such as people with disabilities or affected by high risk graft rejection diseases. The absence of significant quantitative and qualitative differences between the two groups could probably be explained by the regularity, smoothness and depth of a descemetic DALK. Despite this similarity of results, overall, most of patients preferred visual acuity of the eye submitted to PK. Wider study population, selective inclusion criteria and homogeneous follow-up, as well as new methods to investigate quality of vision in patients undergoing corneal transplantation are necessary to support these results. FINANCIAL INTEREST: NONE

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