Experimental studies of the effects of cortisone on the corneal inflammation
[Part Ⅰ] The Effects of Cortisone on Corneal Inflammation Induced by Electrodessication or Chemical Substance.
Since the advent of corticosteroids and their widespread used in various medical problems, their clinical application in the field of opthalmology has gradually increased. It is apparent that the effect of corticosteroids varies according to the method of administration and also to the amount of drugs administered.
The present study was undertaken to determine the influence of cortisone on corneal inflammation of normal rabbits produced by mechanically superficial electrodessication on the central or peripheral portion of the cornea and chemically by instillation of 2% tincture of iodine solution. Investigation of the pathological processes and sequelae in the cornea, and comparative histopathological studies were performed on three groups of rabbits: 1) the control group, 2) the group which received topical cortisone, and 3) the group which received systemic cortisone.
The results obtained were summarized as follows:
1. In the electric cautery group on the central portion of the cornea, there was milder reaction and rapid recovery in the cortisone-treated group. The inflammatory signs in the cornea of the control group began to subside on the 10th day after continuous progression, and left sequelae which consisted of pigment deposition and opacity on the lower part of the cornea Rapid recovery and light opacity were observed in the cortisone-treated groups, but slow healing process and opacity around the burned area were observed in the systemically cortisone-treated group. Inflammatory signs in the iris were milder and healing process was faster in the cortisone-treated groups in comparison with the control group.
2. There was little different feature between the peripheral cautery group and the central cautery group. The cornea, the limbar portion of which was injured with electrodessication, showed more persistent hyperemia on conjunctiva and iris than
in the central cautery group. No marked difference between the topically cortisone-treated group and the systemically cortisone-treated group was observe. Various findings in the cornea were same as in the central cantery group. Active and widespread neovascularization was observed in the cornea of the control group, which was injured with electrodessication on the limbus, and vascularization with some edema was left after clearing of inflammatory reaction. Neovascularization which was apparent in the control group, was observed int he topically cortisone-treated group in lesser degree and non sequelae was left behind after prompt disappearence of the vascularization. The systemically cortisone-treated group showed no neovascularization
3. Same histopathological findings were obtained in both electrodesswicated groups. Bulbvar conjunctiva showed similar finding sin the control and cortisone-treated groups. Thickening due to hyperplasia of epitherlial layer, persistent edema and chronic inflammatory cells were observed in the cornea of the
However, hypoplasia, early disappearance of edema and thinning of the epithelium were noted in the cortisone-treated groups. In the peripheral cautery group, early neovascularization into the corneal parenchyme was observed at the peripheral portion of the cornea, which was not treated with cortisone previously; whereas,
neovascularization appeared in the topically cortisone-treated corneas, and no vascularization in the systemically cortisone-treated cornea. Almost same inflammatory findings in the cornea were found in both the topically and systemically cortisone-treated group. Earlier healing was observed in the iris of the cortisone-treated groups than of the control group.
4. In the iodine injured eyes, clinical findings of both the control group and the cortisone-treated groups were similar, but mile sequelae wre found in the cortisone-treated groups. The cornea of the control group left sequelae of severe degree after healing of the corneal lesion. On the contrary, in the topically
cortisone-treated group, light opacification and unhealed corneal erosion were left. Overall inflammatory process was extensive and left serious sequelae in the systemically cortisone-treated group. Neovascularization into corneal parenchyme disappeared promptly leaving mild sequelae in the cortisone-treated groups, and the inflammatory signs in the iris disappeared much earlier than those in the control group.
5. Histopathological findings in the bulbar conjunctiva of the chemically injured eye showed little difference between those of the control group and tye cortisone-treated groups. Early proliferative change of the epithelial layer, thickening and infiltration of the vascylar bed were observed in the cornea of the control group; whereas, prompt disappearance of the inflammatory reaction, inactive proliferaion of the epithelial layer were observed in the cortisone-treated groups, and there were no thickening. Similar findings were observed in the topically cortisone-treated and the systemically cortisone-treated groups subsides earlier than that of the control group.
Reviewing these experimental results, cortisone inhibits fibroblastic proliferation of the corneal epithelium and parenchyme, so that clinically the healing of the corneal would is delayed is some extent compared with that of the control group. Limbar lesion was healed faster than central lesion. Corneal inflammation due to injuries leaves various sequelae after healing such as corneal opacification, cicatrization and pigmentation. The suppressive actions of cortisone on fibroblastic proliferation, edema, neovascyularization and pigment deposition of the cornea contribute to the minimal sequelae after healing and thus preserve adequate optical function.(Author's Abstract)
[Part Ⅱ] The Effects of Cortisone on the Pyogenic Keratitis.
Corticosterioids, especially cortisone, have been extensively used in the field of ophthalmology since Henderson and Hollenhost used them first against acute nongranulomatous iritis related with rheumatold arthritis in 1950. Recently the combined usage of specific antibiotics along with corticosteroids for the various
bacterial disease of the eye has become prevalent and the attitude of these diseases to antibiotic treatment changed accordingly. There has been unexpected deleterious side-effect as well as beneficial effect from the compared with the used of antibiotics alone.
Author induced corneal inflammation by inoculating coagulase-positive staphylococcus aureus and pseudomonas aeruginosa into the corneal parenchyme of the normal rabbit and assessed the effect of cortisone. Strongly sensitive antibiotics was used topically or systemically combined with cortisone and the results were compared with antibiotics alone treated group by observing the pathological process of the corneal lesions and their sequelae through clinical and histopathological studies.
The results were summarized as follows:
1. The clinical process in the both staphylococcus-inoculated eyes and pseudomonas-inoculated eyes was same; fulminating acute inflammation of the ocular adnexa occured in 24 hours after inoculation and began to subside on the 5th postinoculation day toward the point of spontaneous healing. The inflammation of
the ocular adnexa left persistent sequelae Corneal inflammation left serious sequelae such as heavy opacification, and neovascularizatiion, thus inpairing physiologic optical function. the inflammation caused adhesion between iris and posterior surface of the cornea or lens, and healed spontaneously on the 49th day in the staphylococcus-inoculated group and on the 40th day in the pseudomonas-inoculated group.
2. Chloramphenico was used for the staphylococcal inflammation and polymixin B sulfate, neomycin and chloramphenicol were used for the pseudomonas inflammation. In the antibiotics alone treated group, a milder course and rapid healing were observed as compared with the control group. However, it left serious sequelae as did the control group. Topical application of antibiotics was more effective than systemic application.
3. The combined therapy group with antibiotics and cortisone showed more rapid healing with milder course and minimal sequelae when compared with the antibiotics alone treated group. The following histopathologic findings were observed in the combined therapy group in comparison with the antibiotics alone treated group: 1) earlier healing of the corneal lesion, 2) no thickening of the cornea resulted from inactive fibroblastic proliferation of epitherlial layer, 3) milder proliferative change of the epithelial layer of the cornea, 4) rapid recovery of the endothelia layer from the pathological changes and 5) rapid disappearance of pathological findings in the iris tissue.
4. Topical administration of cortisone brought more pronounced effect than systemic administration.
5. The recurrence of inflammation in the pseudomonas-inoculated eyes after stopping the administration of cortisone signifies the reactivation of bacterial activity, which was suppressed by the concomitant use of antibiotics and cortisone. In the staphylococcus-inoculated group, there was no recurrences of inflammation in the eyes.
6. Healing of the corneal abscess and the disappearance of the invading microorganism were not affected by cortisone, suggesting that cortisone has anti-inflammatory action but no antimicrobial action.
7. Cortisone suppressed fibroblastic proliferation of the corneal epithelium and parenchyme, and brought thinning of the epithelial layer, which was contrary in the antibiotics alone treated and the control groups. Accordingly, cortisone brought
delayed healing in the injured corneal tissue. (Author's Abstract)