Factors Predicting Unsuccessful Big Bubble Deep Lamellar Anterior Keratoplasty

Abstract

Purpose: To evaluate the role of corneal structural resistance as a surgical failure factor in deep lamellar keratoplasty (DLK). Method: A total of 10 eyes of 10 patients underwent DLK at the Ophthalmic Hospital in Rome. The big bubble technique was performed for deep stromal dissection by air injection. Seven patients were affected by advanced keratoconus and corneal thinning ranging from 441 to 235 µm. Two patients were affected by central corneal opacity from herpetic keratitis, and one patient suffered from corneal leucoma caused by bacterial keratitis. Clinical follow-up comprising final astigmatism and visual acuity findings were evaluated with a minimum follow-up of 12 weeks. Results: DLK was successfully performed in eight eyes, five of which were affected by moderate to advanced keratoconus and three by post-infective corneal opacity. In these patients preoperative ultrasonic pachymetry ranged between 441 and 287 µm. In the remaining two patients a perforation of the Descemet’s membrane (DM) occurred while attempting to separate it from the overlying stroma by the big bubble technique, requiring a penetrating keratoplasty (PK) to be performed. In both cases preoperative ultrasonic pachymetry was below 250 µm. Both perforations occurred at a different site than the needle site and at the operative time of the big-bubble injection. Discussion: An ultrastructurally weakened DM may suffer a loss of resistance to a stressing force, becoming unable to tolerate the big bubble technique, and thus being perforated. Since the weakening of the DM is related to end-stage keratoconus corneal thinning, the preoperative corneal thickness rather than the surgeon’s ability can play a major role in surgical failure of DLK. Our study reveals a very high risk of perforation of the DM when pre-operative total pachymetry is below limit of 250 µm.

Descemet's membrane perforation during deep anterior lamellar keratoplasty: Prognosis

“…13 After perforation, the rate of immediate conversion to PKP in the most recent reports ranges from 0% to 100% 7-13 ; including the present series, conversion has been reported in 8 of 53 eyes (15%). [7][8][9][10][11][12][13] The moment of perforation is crucial for the completion and the success of DALK. Early perforations lead to a greater residual stroma and hence slower visual rehabilitation because of a hazy stromal interface.…”

Evaluation of bilateral minimum thickness of normal corneas based on Fourier-domain optical coherence tomography

“…[1][2][3][4][5][6][7][8][9][10][11] Minimum corneal thickness (MCT) is an important parameter in surgical planning and in the detection of pathology in certain corneal and refractive surgery procedures, in which accurate assessment of MCT and its location is crucial. [12][13][14][15][16] Errors in pachymetric measurement are factors in poor surgical outcomes, including ectasia after laser in situ keratomileusis. [17][18][19] Corneal topographic assessment can be inaccurate in the presence of motion artifacts.…”

Intraoperative perforation of Descemet's membrane during “big bubble” deep anterior lamellar keratoplasty

“…Descemet's membrane perforation has been reported to occur in 9-23% of cases in various case series of big bubble DALK [9][10][11][12][13].…”

“…In a study by Michieletto et al [9], deep lamellar keratoplasty was attempted in ten eyes of ten patients (keratoconus 7, post-infective corneal opacity 2 and corneal leukoma 1). The surgery was successfully performed in eight eyes.…”