Erling Grønvold Olsen

CHANGES OF THE CORNEA ENDOTHELIUM AFTER ULTRAVIOLET RADIATION

The rabbit cornea endothelium has been studied with specular and scanning electron microscopy after exposure with a commercially available ultraviolet lamp. The animals were plased 50 cm from the source, and most experiments were run with a 20 min exposure time. In the specular microscope, the endothelium revealed numerous circumscript reflex‐free areas, which were observed from 4 days up to 8 months after the irradiation. A wide varity of changes were found in the scanning electron microscope. One day after the exposure the cells showed indistinct outlines, and they were bulging into the anterior chamber. In some regions the pattern was dominated by marked grooves preferentially along the cell demarcations, whereas other regions showed rough surfaced cells because of cytoplasmic projections and grainy deposits. At the 3 days stage there was a marked pleomorphy, and some cells were on their way to being rejected. After one week the cobblestone appearance of the endothelium was about to decline. Partly rejected cells were still common. In addition, distinct, ringshaped local impressions occurred imitating the previous described grooves. This phenomenon along with some single endothelial cells studded with microvilli were the abnormal findings 8 months after the damage. It is concluded that although ultraviolet radiation is largely absorbed in the cornea, the threshold dose for damage of the endothelium is not beyond those used for practical purpose. The endothelium was surprisingly resistent towards repeated radiation damage.

The healing of rabbit corneal endothelium.

A circular 4 mm endothelial defect was induced by transcorneal freezing. The experimental damage and the healing took place in the living rabbit in 15 eyes, and in the isolated cornea in organ culture in further 20 eyes. The reparative process was studied by SEM, and proved to be the same in vivo and in vitro. The defect was covered with endothelial cells after 3 days. The normal hexagonal pattern was regained after 3 weeks. Both cell migration and cell division were involved in the reparative process. Only cells recruited from a zone close to the defect were active; the cells situated more than a few cell diameters from the original edge maintained their form and size unchanged. The first phase of cell division was the formation of a spherical cell with numerous blebs on its surface.

Transient breakdown of the retinal pigment epithelium diffusion barrier after sodium iodate: A fluorescein angiographic and morphologic study in the rabbit

The breakdown and regeneration of the retinal pigment epithelial barrier was studied in rabbits after intravenous injection of 5 ml of a 2% saline sodium iodate solution. Fundus fluorescein angiography showed profuse barrier leakage from 24 hr up to 7–8 days after the injection. At this time the barrier became closed in the course of a further 1–2 days, after which the fundus gradually developed an abnormal, coarsely grained appearance. Light microscopy 3–4 days after the injection revealed a marked damage of the retinal pigment epithelium with large intercellular gaps and numerous macrophages. In addition, the number of choriocapillary lumina was reduced and the endothelial fenestrations were lacking. After 18–22 days a continuous cell layer with many intercellular contacts replaced the pigment epithelium. This layer seemed to act as a functionally tight barrier from the 9th day after the injection. The transient hypotony after sodium iodate injection is thought to be due to an accessory aqueous outflow through the damaged pigment epithelium.

Human cornea endothelium and ultraviolet radiation.

Reflex‐free areas of the cornea endothelium are demonstrated by specular microscopy after heavy bilateral photokeratitis. The changes are believed to be caused by UV‐radiation.

THE HEALING OF HUMAN CORNEAL ENDOTHELIUM An in vitro study

A 4 mm circular defect was made on the endothelium by transcorneal freezing of 5 normal human corneas. The eyes were enucleated because of malignant tumours, patient age 3 to 74 years. After excision, the corneas were kept in culture medium for 3 (4) days, and subsequently prepared for SF.M. At this stage, the defect was covered with endothelium, whose origin was a narrow zone adjoining the edge of the defect. The endothelium on the peripheral, undamaged part of the cornea did not seem to take part in the repair process, neither by proliferation, enlargement nor by migration. Dividing cells were found scattered on the damaged area. The repair process was found to be similar in all five eyes, irrespective of the age of the patient. In organ culture, the healing of corneal endothelial defects is similar in rabbits and in humans.

HLA B27, Sacro-Iliitis and Peripheral Arthropathy in Acute Anterior Uveitis

Thirty-four consecutively admitted patients with acute anterior uveitis (AAU) were examined. The male to female ratio was 1.8:1. Twenty-two patients (67%) were HLA B27 positive. Twelve (36%) had radiographical sacro-iliitis; all were males and were HLA B27 positive. Three of them were asymptomatic. Eighteen patients (53%) had low back pain suggestive of sacro-iliitis, but this symptom was associated neither with radiographical sacro-iliitis nor with HLA B27. Radiographical sacro-iliitis and HLA B27 occurred together more frequently in males than in females. It was concluded that the association between AAU and signs of joint affection reflects the association seen in HLA B27 positive patients, while HLA B27 negative patients suffered from low back pain as well. HLA B27 positive patients with AAU should be remitted for radiographical examination of the sacro-iliac joints.

Anterior mesenchymal dysgenesis of the eye Congenital Hereditary Endothelial Dystrophy and Congenital Glaucoma

Abstract. The present report describes a patient with congenital glaucoma and iris hypoplasia who underwent repeated surgery to control the glaucoma. Despite these procedures, the patients corneas opacified progressively, and bilateral penetrating keratoplasties were performed. Histopathological studies, including transmission and scanning electron microscopy of the corneal buttons, demonstrated specific changes of Descemets membrane and the endothelium typical of congenital hereditary endothelial dystrophy (CHED). CHED has usually been considered to be a specific clinical entity that is not combined with congenital glaucoma or other significant abnormalities of the anterior segment of the eye. The present case indicates that these conditions may be combined, which is of importance when dealing with infants with congenital glaucoma and corneal opacities.

The effect of steroids on the healing of the corneal endothelium. An in vivo and in vitro study in rabbits.

The effect of steroids on the repair of a corneal endothelial defect in rabbits was studied by in vivo and by organ culture experiments. A standard 4 mm defect was produced by transcorneal freezing. The situation after 2, 3, and 4 days was studied by scanning electron microscopy. Preliminary experiments demonstrated that topical eye treatment influenced on the repair process of the untreated, contralateral eye. The preservants of commercial eye drops caused delayed healing in organ culture. These effects were excluded from the control experiments. Topical eye treatment with steroid eye drops for 3 days caused a one day delay in the repair process. In culture medium, delayed repair was found at hydrocortisone concentrations ≥ 0.125 mg/ml. The visible influence of hydrocortisone increased with the concentration in the range examined, between 0.05 mg/ml and 1 mg/ml.

Experimental epithelial ingrowth. Epithelial/endothelial interaction through a corneal perforation, studied in organ culture.

Abstract. The interaction of confronting corneal epithelium and endothelium has been studied by cultivation of corneas with open perforating wounds. In some experiments, the epithelium and the endothelium were initially damaged adjacent to the perforation, and the repair capacity was reduced by adding steroids or colchicine to the culture medium. The specimens were examined by scanning electron microscopy. The epithelium covered the stromal walls of the open perforation within 3 days. In most experiments, the epithelium and the endothelium met at the cut edge of Descemets membrane, and this appeared to be a stable situation. However, if the endothelium was damaged and had reduced repair capacity, the epithelium invaded Descemets membrane. The clinical implication is that the risk of epithelial ingrowth is present in eyes with a pathological endothelium.

Influence of colchicine on the healing of corneal endothelium.

Abstract. The healing of a corneal endothelial defect involves cell division and cell migration. Microtubuli form the spindle‐fibers and parts of the cytoskeleton, and may therefore play a role in these cellular processes. In the present study colchicine is used in tissue culture to inhibit the assembly of microtubuli. Colchicine causes not only an arresting effect on cell division in the metaphase, but also an inhibitory effect on the cell migration. This latter effect is demonstrated by the radially directed, spindle‐shaped cells seen in the repair zone of the control corneas being replaced by flat rounded cells. In this respect, in the presence of colchicine, the corneal endothelial cells behave like fibroblasts and not like epithelial cells.