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Sara Touhami, Otman Sandali, Laurent Laroche, Vincent M Borderie; Predictive factors for successful corneal dissection using the big bubble technique during deep anterior lamellar keratoplasty: An Optic Coherence Tomography-based Study. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):3973.
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© ARVO (1962-2015); The Authors (2016-present)
To analyse the predictive factors of a successful Type1-Big Bubble (T1BB) during deep anterior lamellar keratoplasty (DALK) using Optic Coherence Tomography (OCT).
Prospective observational study of all patients undergoing DALK by the same experienced surgeon (VB) between January 2003 and June 2014 at the Quinze-Vingts Hospital, Paris. For each patient, clinical and OCT data was collected preoperatively: corneal disease, best corrected visual acuity (BCVA), central and minimal corneal thicknesses (CT), difference between maximal and minimal (∂1) and median and minimal (∂2) CT, Sandali’s OCT classification (SOC) when the disease was keratoconus (KC) and presence of stromal scars on OCT; and perioperatively: diameter and depth of trephination. All variables were correlated to the occurrence of a successful T1BB as described by Anwar and Dua using T-student, Fisher exact and Bonferonni post-hoc tests.
236 patients underwent DALK during the study period: 72,5% for KC (n=171), 8,5% for corneal dystrophies (n=20), 9,7% for Herpes (n=23) and 9,3% for corneal scars related to other diseases (n=22). Median age was 33 years (Range:13-83). Successful T1BB dissection was possible for 107 patients (45%). Among the 55% patients for whom dissection was completed manually, perforation occurred in 19% of the cases (n=25). OCT data was analysed for the 56 patients who benefited from OCT using the same Optovue RTvue® device. The occurrence of a T1BB was not correlated to age, corneal disease, BCVA, central and minimal CT or trephination diameter. It seemed correlated to a ∂1 CT>220um (p=0.017) a ∂2 CT>110um (p=0.075}, a stage 3 or 4 KC based on SOC (p= 0.03), presence of scars in the posterior stroma (p=0.0005), and trephination depth (p=0.014).
DALK has obvious advantages over penetrating keratoplasty at the cost of a steep learning curve, which the BB technique has facilitated. However, T1BB aspect is not constant even for experienced surgeons and manual dissection with a risk of perforation is often necessary when the BB fails. This study showed for the first time the value of easily available preoperative OCT parameters to predict the success of a T1BB and DALK outcome, which can help with the surgical decision and avoid complications especially during the learning phase.
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