G.A. van der Veen

Refractive surgery for high myopia

Surgical correction of high myopia is indicated in a limited number of cases. Techniques include (epi)keratophakia, keratomileusis and implantation of a negative-power IOL. The iris claw lens, fixed to the midperiphery of the iris, has proved its safety in aphakic eyes. The model has been adapted by giving it a vault in order to make it suitable for implantation in high myopic phakic eyes. The implantation technique and short-term results of patients operated by Worst are presented.

Cell-ingrowth in a silicone plombe

A male patient (42 years) who had been treated for retinal detachment by the implantation of a silicone plombe into the sclera, returned to the clinic 8 years after implantation because of inflammation of the tissue and partial protrusion from the sclera. After removal of the plombe this was processed for TEM and SEM and examination of the plombe material after 8 years in situ could be carried out in order to get information about the cell-biomaterial interface. A large proportion of the silicone pores was filled with cellular material, including macrophages, giant cells and erythrocytes thus indicating a foreign body granuloma. The external surface of the pores showed a granular osmiophilic dense amorphous layer including extracellular debris. Engulfing of silicone particles by macrophages and the evidence of long-term tissue response suggest partial biodegradation of the silicone and certainly not complete inertness as was formerly claimed.

Reaction of the rabbit corneal endothelium to nylon sutures

Nylon and stainless steel sutures separately placed deeply into rabbit corneas by splitting the stroma for a few millimeters, without closing sutures, remained in the cornea for two, four and six weeks respectively. In contrast to the stainless steel sutures an extensive tissue reaction could be observed clinically around the nylon sutures within a few days and was still present after 4–6 weeks. On the endothelial side, covering of the nylon with fibroblast cells took place very slowly, this in contrast with stainless steel. Irritation of the tissue and an oedematous appearance of the endothelium around the nylon suture was the result. At first a kind of collagen network, often mixed with inflammatory cells, was deposited on the nylon material before fibroblast cells could grow in. Covering of the stainless steel started quite soon after implantation, without preliminary deposition of collagen material. The reason for this phenomenon must be sought in the high free surface energy of the stainless steel, which attracts cells, in contrast to nylon which has a very low free surface energy.

Secondary cataract material collected with a glass cannula

Secondary cataract material from three patients, collected with a glass cannula approx. 18, 24 and 30 months respectively after operation, was prepared for SEM examination. For the soft samples this was done by filtration through a millipore filter followed by fixation and drying. The more solid material was suspended in a fixation solution, followed by centrifuging, suspension in 70% ethanol and drying on a specimen-holder. The short residence samples (18 months) showed mainly erythrocytes, some (inflammatory) cells and degenerated lens-fibre material. Most of the more solid material, which was collected more than 20 months after operation, showed fragments of (regenerated) capsule epithelium and pieces of solid lens-fibre material with fragments of capsule epithelium attached.

Morphological aspects of human lens capsules

Lens capsules of patients of advanced age, obtained after extracapsular cataract surgery, were carefully prepared for a combined LM, TEM and SEM investigation, after preliminary washing and mounting onto a holder in a buffer solution. After pre-fixation with GA, samples were postfixed for LM/TEM and OsO4/K4Fe(CN)6 and stained with toluidineblue/basic fuchsine for LM and with uranyl acetate/lead citrate for TEM; for SEM the GA-pre-fixed samples were post-fixed by the Tannine Arginine-OsO4 non-coating technique. At LM-level discrimination between healthy and degenerating cells was possible after toluidine staining. At SEM-level protrusion of the cell nucleus and fibrillation and blebbing of the cell membrane as the result of capsular degeneration could be observed with the TAO-method. At TEM-level protrusion of the cell nucleus, degeneration of the cytoplasm, ballooning of the mitochondria, the presence of microfilaments and the occurrence of vacuoles were visible as the result of capsular degeneration on cataract formation.