Michieletto Paolo, Balestrazzi Alessandra, Balestrazzi Angelo, Mazzotta Cosimo, Occhipinti Igor, Rossi Tommaso
Ophthalmic Hospital, Rome, Italy.
Ophthalmologica. 2006;220(6):379-82. doi: 10.1159/000095864.
To evaluate the role of corneal structural resistance as a surgical failure factor in deep lamellar keratoplasty (DLK).
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 microm. 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.
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 microm. 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 microm. Both perforations occurred at a different site than the needle site and at the operative time of the big-bubble injection.
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 microm.
评估角膜结构阻力作为深板层角膜移植术（DLK）手术失败因素的作用。
10例患者的10只眼在罗马眼科医院接受了DLK手术。采用空气注射大泡技术进行深层基质剥离。7例患者患有晚期圆锥角膜，角膜变薄范围为441至235微米。2例患者因疱疹性角膜炎导致中央角膜混浊，1例患者因细菌性角膜炎导致角膜白斑。对包括最终散光和视力结果在内的临床随访进行了评估，最短随访时间为12周。
8只眼成功进行了DLK手术，其中5只眼患有中度至重度圆锥角膜，3只眼患有感染后角膜混浊。这些患者术前超声角膜测厚范围在441至287微米之间。其余2例患者在试图通过大泡技术将Descemet膜（DM）与上方基质分离时发生了DM穿孔，需要进行穿透性角膜移植术（PK）。在这两例中，术前超声角膜测厚均低于250微米。两个穿孔均发生在与穿刺部位不同的位置，且发生在大泡注射手术时。
超微结构上减弱的DM可能会失去对压力的抵抗力，无法耐受大泡技术，从而被穿孔。由于DM的减弱与终末期圆锥角膜的角膜变薄有关，术前角膜厚度而非手术医生的能力在DLK手术失败中可能起主要作用。我们的研究表明，术前总角膜厚度低于250微米时，DM穿孔的风险非常高。
