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Cornea and Refractive Surgery Department, "Instituto de Microcirugía Ocular," Barcelona, Spain
Cornea and Refractive Surgery Unit, University Hospital, Vall d’ Hebron, Barcelona, Spain
Accepted for publication 17 July 2002
Keywords: posterior lamellar keratoplasty; endothelial failure
We describe the technique and the results of three cases where we performed a posterior lamellar keratoplasty.
Case reports
The following surgical technique was performed in all cases. The donor posterior button was obtained from an entire fresh globe. We made sure that intraocular pressure was adequate by injecting BSS (balanced salt solution, Alcon) in the vitreous cavity. With a Moria ONE microkeratome, an anterior cap of 250 µm was cut and lifted. A Barron trephine 7 mm in diameter was used to obtain the posterior button, covered afterwards with viscoelastic to protect it and to avoid desiccation.
With our microkeratome an 8.5 mm in diameter, nasal hinge and 250 µm flap was obtained. The trephination was made with a 7 mm Barron trephine and completed with corneal scissors, under viscoelastic protection.
After the intraocular injection of acetylcholine the posterior donor button was placed on the recipient eye under viscoelastic protection. Six 10-0 Nylon interrupted sutures were used to secure and close the wound. Immediately after, the flap was put back and fixated with six interrupted 10-0 Nylon sutures and the knots were buried. The viscoelastic anterior chamber was exchanged with BSS using an automatic pressure controlled irrigation-aspiration system.
Case 1
This was a 36 year old woman with Fuchs’ endothelial dystrophy. Preoperative BSCVA was 0.4 in the right eye and 0.6 in the left. Slit lamp examination showed diffuse corneal oedema clearly affecting the anterior layers of the cornea. Endothelial cell count (ECC) was below 900 cells/mm in both eyes. Surgery was performed on the right eye (Fig 1A
). The follow up was done for 12 months (Fig 1B
).
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Case 3
This was a 57 year old man with history of myopia in both eyes (right eye -4.00, left eye -9.00). There was a history of subretinal macular neovascularisation and cataract extraction in his left, surgical, eye, with an ECC of 950 cell/mm. Preoperative BSCVA was 0.5 in the right eye and 0.2 in the left. The follow up was done during 14 months (Fig 1D).
Examinations in all cases were at day 1, 1 week, 3, 6, 9, and 12 months. All Nylon sutures were removed before the 6 month control.
All surgeries were technically uneventful. The immediate and late postoperative controls showed transparency of the cornea and no signs of rejection. In case 1 at the time of removing the superior suture (3 months postoperatively) a separation between the anterior cap and the edge of the corneal recipient eye was observed (because of the stromal flap oedema) and two interrupted 10–0 Nylon suture were placed for 3 more months.
Uncorrected and BSCVA did not improve in all cases in spite of corneal transparency (Table 1). We observed a significant increase in astigmatism in all cases during the follow up and also after the suture removal,1 but it was not the main cause of reduced vision (Table 2). We checked vision changes with refraction over rigid gas permeable lenses but the results were lower than expected.
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Reviewing our experience during the past 6 years in performing penetrating keratoplasty (PK) for Fuchs’s dystrophy, and obviously understanding that this is not a comparative study, we realised that our mean improvement in best corrected visual acuity was 3.1 lines (range 0–8), with a mean postoperative time for visual rehabilitation of 8 months (range 3–18 months).
The recovery time was slower when compared with PK, perhaps because of the optical distortion of the interface. We must also not forget that we sutured both the donor button and the superficial lenticule, perhaps inducing interface distortion. Also it is important to mention the risk of wound leakage and interface aqueous humour dissection.
We think that the time of graft deswelling was not as expected because at the time of suture removal a separation was noted between the anterior cap and the recipient eye in cases 1 and 2. We placed sutures in this site but the time of suture removal was extended to 12 months. Another contributing factors would be host-graft disparity, trephination, and suture technique.5
In our experience this technique shows that it is possible to change only the posterior layers of the cornea with successful anatomical result. Nevertheless, from a functional perspective penetrating keratoplasty has been a much better and faster approach and, in fact, in both techniques we are replacing the endothelium using an open sky technique.
References