Abstract
Purpose: :
In diseases of the posterior part of the cornea like scarring, endothelial resp. descemet's dystrophy it is sufficient to exchange the affected posterior cornea and preserve the anterior part, which is most important for refraction, tear film and tissue stability.
Methods: :
A microkeratome cut with a nasal hinge is performed on patient's cornea (9-10.5mm diameter). The residual underlying tissue is trephined and exchanged with a donor button, prepared with a microkeratome and a corneal trephine on the artificial anterior chamber of the ALTK system. Following graft exchange the superficial flap is readapted and sutured. For better adhesion air is put into the anterior chamber for 2 min. No viscoelastics are used. The surgeries have been performed since June 02 on 52 eyes of 44 patients. Diseases: Fuchs' Dystr., surgery related keratopathy, glaucoma, scar. The cases are devided into 3 groups, depending on type of microkeratome (250µ, 350µ, 400µ), Tx-diameter and suture technique (10-0 nylon).
Results: :
Minimum follow-up is 1 year. Gr.1(n=19): diff. depht of cutting, diff. Tx-diameter and diff. suture technique. Gr.2(n=14): Tx-diameter 7.5mm, Gr.3(n=19): Tx-diameter 8.0mm. Gr.2 and Gr.3: keratome 250µ, H-suction ring, 16 single stitches. Suture removal: 4-6 months postop. Mean follow-up (months): Gr.1: 40, Gr.2: 39, Gr.3: 26. Between the groups there are no remarkable differences concerning postop. visual acuity (mean 0.64 excl. macula diseases), refractive astigmatism (mean 1.53 D), refraction, endothelial cells (36m postop: mean 1130/mm² cells, n=15) and corneal thickness (36m postop: mean 564µ, n=15; US Tomey SP2000). No detachment of an implant occured. 4 primarily clear transplants had to be exchanged between 12/06 and 11/07 because of progressive opacity related to different additional diseases resp. surgeries. The Tx-exchanges were easy to perform through a temporal clear cornea incision. All corneas are clear now.
Conclusions: :
Postop. corneal thickness depends on the choice of the microkeratome. In comparison with perforating keratoplasty wound healing is faster, earlier suture removal. The remaining thick superficial part of the cornea guarantees less corneal surface problems and stable anatomical results. This leads to early rehabilitation with fast increase of postop. visual acuity and minimal induced astigmatism.
Keywords: cornea: clinical science • transplantation • cornea: endothelium