New lamellar keratoplasty techniques: posterior keratoplasty and deep lamellar keratoplasty

Posterior keratoplasty is a new surgical technique that may be valuable in treating patients with corneal decompensation secondary to endothelial dysfunction. There are currently two approaches to posterior keratoplasty. In the first approach, a corneal flap is created using a microkeratome (similar to laser in situ keratomileusis flap), and posterior stromal tissue is excised (by trephination or excimer laser keratectomy). In the second approach, a deep stromal pocket is created across the cornea through a superior scleral incision. A custom-made flat trephine is inserted into the pocket to excise a posterior lamellar disc. Preliminary studies have shown the feasibility of performing these techniques in sighted human eyes. Despite potential advantages, further clinical studies are needed to determine whether these techniques reduce interface scarring, astigmatism and graft rejection, improve visual outcomes, or are potentially an alternative for penetrating keratoplasty.     

Intralamellar dissection techniques in lamellar keratoplasty

PURPOSE: To evaluate and compare the efficacy of the four adjunctive agents to facilitate recipient bed intralamellar dissection in cases of lamellar keratoplasty. METHODS: Forty eyes with partial-thickness corneal opacities were recruited for this prospective, randomized clinical trial. The cases were divided into four groups per the intralamellar injection (i.e., air [group I], 2% hydroxypropyl methylcellulose [HPMC] [group II], balanced saline solution [BSS] [group III], and no adjunct [group IV] used to facilitate recipient intralamellar dissection). The intraoperative parameters evaluated were initial preparation time, dissection time, and total time. At each follow-up, visual acuity, refractive status, keratometry, and endothelial cell counts were also analyzed. RESULTS: Initial preparation time, dissection time, and total time were significantly decreased with the use of an adjunct (p < 0.05) and were found to be least with the use of BSS. No difference in these time frames was noted between group I and group II. Corneal haze and incomplete air insufflation were seen in group I, and difficulty in injection of 2% HPMC and its incomplete spread were noted in group II. The mean spherical equivalent, astigmatism, endothelial cell counts, and visual acuity did not show any significant difference between any group. CONCLUSION: Hydrodelamination with BSS is easy to perform and should be undertaken routinely to facilitate recipient intralamellar dissection.     

Deep lamellar keratoplasty

INTRODUCTION: Deep lamellar keratoplasty (DLKP) is a surgical technique in which the entire corneal stroma is removed down to the Descemet membrane. METHODS: The difference between deep lamellar keratoplasty and classic lamellar keratoplasty is qualitative rather than quantitative. In the first technique, the anatomical cleavage plane provides clear separation of the stroma and the Descemet membrane. This plane has a clear and smooth surface. On the contrary, classic lamellar dissection down to 2/3 of the stroma results in a very rough and uneven surface with a risk of low visual acuity. PURPOSE: To compare the results of 200 cases treated with deep lamellar keratoplasty and 200 cases of penetrating keratoplasty (PK). RESULTS: No rejection episodes were recorded in the 200 patients who underwent DLKP surgery, whereas rejection occurred in 4% of the patients after PK. The number of endothelial cells, measured with a Konan instrument 1 month after removal of the sutures in patients who underwent deep lamellar keratoplasty, was double that in patients who underwent penetrating keratoplasty. CONCLUSION: The number of endothelial cells does not change after DLKP, but is substantially reduced after PK. The degree of astigmatism is greatly reduced and functional recovery is faster with the first technique. These are the main reasons why we think that DLKP could replace PK as the best procedure in all cases in which no endothelial damage is involved.     

Impact of new lamellar techniques of keratoplasty on eye bank activity

Background Deep anterior lamellar keratoplasty (DALK) has become an increasingly popular alternative to penetrating keratoplasty in patients with stromal corneal pathologies. The main advantages of DALK are: prevention of long-term endothelial loss, elimination of allograft reaction and short topical steroid treatment with lower risks of glaucoma, cataract and infection. Because this technique enables surgeons to use corneal grafts with low endothelial density, the aim of this paper was to determine whether this type of innovation has had a significant impact on eye bank activity.Methods We reviewed our corneal graft activity over a 40-month period and assessed the proportion of deep lamellar and penetrating keratoplasties. During the same period, we also evaluated our eye bank activity and recorded the utilisation of grafts with endothelium abnormalities, which were only suitable for lamellar techniques.Results Deep lamellar keratoplasty represented 29.8% (85 out of 285) of corneal transplantations. Forty-eight percent of all corneas stored at the local eye bank were unsuitable for penetrating keratoplasty; 36.6% of those were not suitable for endothelial deficiencies. Among these, 72.7% were used for DALK and 27.3% were rejected. This permitted a 24.5% increase in corneal grafting activity. In contrast, Descemet’s membrane was removed at the time of surgery in 12% of corneas with healthy endothelium, which was used for deep lamellar keratoplasty.Conclusions Deep anterior lamellar keratoplasty development and close collaboration between eye banks and surgeons can induce a significant increase in corneal grafting. This could be a partial solution in countries confronted with corneal graft shortages.Presented at the annual meeting of the European Eye Bank Association at Halle/Saale, 14–16 January 2005.This paper obtained the Best Presentation Award from the XVII EEBA Awards Committee.