Corneal Endothelial Damage Research Articles

Corneal endothelial damage caused by different types of incision

Abstract The effects of corneal incisions of different types on the corneal endothelium in cadaver eyes was studied by scanning electron microscopy. In all cases the perforations were made with a diamond knife, but in case 1) the opening was enlarged in both directions with scissors, in case 2) a partly perforating groove was made on one side, and an enlargment only with sciccors on the other, and in case 3) a long full thickness incision with diamond knife only was made. The greatest damage to the endothelium was induced by the scissors, the damage was less when partial thinning was performed before the opening with scissors, and the least trauma was seen when a diamond knife only was used. The cell loss was maximally calculted to be about 8% of the endothelial cell population when incision with scissors was performed compared with 2–3% with diamond knife incision.

Cat endothelial morphology after corneal transplant

The cat has been suggested as a superior model to evaluate penetrating keratoplasty and corneal endothelial damage and repair. Morphologic change is felt to be a sensitive indicator of endothelial stress response. We documented corneal thickness and endothelial morphometric parameters of eight cats before and after homograft penetrating keratoplasty using an Eisner contact glass. One-hundred-cell samples from preoperative and 6.18 +/- 0.57 weeks and 9.25 +/- 0.84 months (means +/- standard errors of the means) postoperative photomicrographs were computer analyzed. Cell density (cells/mm2), coefficient of variation of cell area, percent hexagonal cells, and mean figure coefficient were measured. Values are given as means +/- standard errors of the means. Preoperative coefficient of variation for area, 19.1 +/- 0.4, was significantly greater (22.0 +/- 1.0) six weeks after surgery. At nine months, cell density (1487 +/- 114) and percent hexagonal cells (59.6 +/- 2.1) were significantly less than six week values (cell density = 2053 +/- 201, percent hexagonal cells = 68.1 +/- 1.5) and preoperative values (cell density = 2395 +/- 94, percent hexagonal cells = 69.3 +/- 1.1). Thus there is evidence of polymegethism six weeks after surgery and persistent decreased cell density and pleomorphism nine months after surgery.

Silicone oil in the anterior chamber.

A total of 42 cases (42 eyes) with silicone oil in the anterior chamber after pars plana vitrectomy (PPV) and after silicone oil injection into the vitreous cavity (SIV) were analyzed. The main complications caused by silicone oil were corneal endothelial cell damage and secondary glaucoma. Specular microscopy showed decreased cell density, apparent pleomorphism of endothelial cells, and increased corneal thickness. In some cases, edematous and necrotic endothelial cells were found. The characteristic optical artifacts resulting from silicone oil coming into contact with the endothelium, such as a bright reflex, reversed pattern of illumination, and interference fringes, were also observed. There was a definite correlation between elevated intraocular pressure (IOP) and the presence of silicone oil in the anterior chamber; the IOP dropped significantly on removal of the oil. The treatment and prevention of conditions involving silicone oil in the anterior chamber are briefly discussed.

Posterior corneal folds and endothelial cell damage in human donor eyes.

Posterior folds in human donor corneas stored as whole eyes in moist chambers, or isolated in McCarey-Kaufman medium at 4 degrees C, have been studied by light and scanning electron microscopy to determine whether or not endothelial cells on the folds are damaged. Extensive, often irreversible cell damage was found associated with most of the folds. Hence posterior folds in donor corneas are of importance in that they indirectly reduce the quality of the donor cornea for transplantation.

In vitro evaluation of iris chafe protection afforded by hydrophilic surface modification of polymethylmethacrylate intraocular lenses

An in vitro iris chafe test was developed to evaluate possible differences in abrasive interaction of various intraocular lens (IOL) materials with the posterior surface of the iris. The materials that were compared in initial tests with rabbit irides were high molecular weight polymethylmethacrylate (PMMA), the primary IOL material in current use, and surface-modified PMMA, which had a permanent, chemically bound, hydrophilic, polymer surface. Scanning electron microscopy, light microscopy, and examination of histological sections were used to assess tissue damage. A “window defect” type of abrasive damage was observed by light microscopy for PMMA lenses and is very similar in appearance to that seen for iris abrasion by human implants when viewed in vivo in slitlamp examinations. Results for both pigmented and albino rabbit irides indicate a reduction in abrasive insult to the external iris basement membrane and underlying pigment epithelium by the hydrophilic surface modification of PMMA. These results are consistent with our observation of a major reduction in corneal endothelium damage on contact with the hydrophilic surface-modified PMMA as compared with PMMA itself. This in vitro iris abrasion test, therefore, appears to be a useful technique for future evaluation of IOL surface properties.

Toxic Endothelial Degeneration in Ocular Surface Disease Treated With Topical Medications Containing Benzalkonium Chloride

We examined a 56-year-old man with keratoconjunctivitis sicca and marked ocular surface disease in whom the prolonged frequent use of topical medications containing the preservative benzalkonium chloride was associated with corneal endothelial damage requiring corneal transplantation in one eye. The histopathologic findings on examination of the excised button were consistent with toxic endothelial disease. Postoperatively, the patient's symptoms continued until the preservative-containing medications were substituted with nonpreserved saline eyedrops.

Complications in the Ventilated Patient

The use of mechanical ventilation may subject patients to a variety of complications and adverse effects. Certain complications may be a direct result of mechanical ventilation, whereas others seen in association with this modality of therapy appear to be related to concurrent conditions and the severity of underlying disease. The incidence, evaluation, and management of major complications associated with mechanical ventilation are reviewed.

Postoperative grey-white lines of the posterior cornea and endothelial cell damage.

'Snailtracks' (grey-white streaks and patches on the posterior corneal surface which occur postoperatively) have recently been implicated as possible markers of corneal endothelial cell damage. We have examined this phenomenon in vivo with the slit-lamp and specular microscope. We recognised three types of linear form and, in contradiction of other observers, found that each was always coincident with a wrinkle in Descemet's membrane. Moreover, we were able to demonstrate only minimal endothelial cell damage in only a few of the tracks.

Comparison of the effect of polymethylmethacrylate and silicone intraocular lenses on rabbit corneal endothelium in vitro

An in vitro comparison of corneal endothelial damage caused by polymethylmethacrylate and by silicone intraocular lenses was made. Endothelial damage was assessed by vital staining of corneal endo thelium immediately following direct contact with an intraocular lens. Silicone lenses produced less damage than polymethylmethacrylate lenses. The difference could be attributed to a specific type of damage—membrane stripping—seen only after contact with poly methylmethacrylate lenses.

Changes of MK medium during storage of human cornea.

By comparing the composition of McCarey-Kaufman (MK) medium before and after corneal storage we attempted to identify specific physiological changes in the medium as predictors of tissue damage. We also tried to determine if hydrocortisone (a lysosomal membrane stabiliser) added to the medium could reduce tissue damage during storage. Corneas (human and rabbit) were stored in the MK medium with and without hydrocortisone for 4 days at 4 degrees C. The water and nitrogen contents of the stored cornea were compared with those of the fresh cornea. The medium was analysed before and after corneal storage to determine the concentrations of glucose, protein, and amino acids as well as pH and osmolarity. Scanning electron microscopy (SEM) was used to estimate the degree of the corneal endothelial cell damage. The nitrogen contents and dry weights of the steroid treated and untreated stored corneas were similar to those of the fresh unstored cornea. The steroid treated cornea contained a lesser amount of water than the untreated cornea. The cornea stored in medium without steroid took up a greater amount of glucose from the medium than the cornea stored in medium with steroid. As compared with their concentrations in the fresh unused medium the concentrations of leucine, lysine, and glycine were lower and that of glutamic acid was higher in both the media used for corneal storage. However, the steroid treated storage medium as compared with the untreated storage medium had a greater reduction in the lowering of leucine, lysine, and glycine, and a lesser reduction in the increase of glutamic acid. Steroid treated medium also had a lesser amount of protein released from the stored cornea. Changes in the pH and osmolarity of the media before and after corneal storage were not remarkable. SEM showed that the endothelial cells of the cornea stored in the medium containing steroid were less damaged than those of the cornea stored in the medium without steroid.

3-amino-triazole effects on the eye of young and adult rabbits in the presence and absence of hydrogen peroxide.

3-aminotriazole (3AT) is known to reduce catalase levels in ocular tissues when given intravenously or orally. Rabbits were given either 4 ml/kg of a 3M solution of 3AT intravenously or a 2% solution as drinking fluid. Intravenous 3AT administration was followed at 4 hrs by an intracameral injection of hydrogen peroxide (H2O2) to give an aqueous humor concentration of 3.2 mM in young (4-6 weeks of age) and a 3.3 mM in adult (6 months of age) rabbits. Tissues were taken for microscopy at either 6 or 24 hours after intracameral H2O2. Neither oral nor intravenous 3AT alone in adult rabbits, or intravenous 3AT in young rabbits, had any effect on either iris, ciliary process, or corneal endothelial morphology. After oral 3AT in adult rabbits, H2O2 caused highly edematous ciliary processes with dilated vessels; corneal endothelial cells were swollen. Previous studies in adult and young rabbits have shown that intracameral H2O2 alone caused few morphological changes in young, but marked changes in the adult that correlated with the 35 to 50% lower catalase levels found in iris and corneal endothelium, respectively, in adult ocular tissues. Young rabbits pre-treated with intravenous 3AT, when examined at 6 and 24 hours after intracameral H2O2, showed swollen ciliary processes, vessel dilation, alteration of the pigment epithelium and corneal endothelial damage. In non 3AT-treated young rabbits, H2O2 caused only minor morphological changes. In adult animals at 6 and 24 hours after intracameral H2O2 the ciliary processes were edematous in the absence of 3AT; after intravenous 3AT and intracameral H2O2 the changes were even more marked, with very severe swelling of ciliary processes and corneal endothelial damage. It is apparent that the decrease in catalase caused by 3AT allows H2O2 to induce damage even in young animals where it usually does not induce morphological changes. In adult animals, the effects of H2O2 are enhanced in the presence of 3AT.

>The Relation between Preoperative Polimegathism and the Damage of Corneal Endothelium after PCL Implantation

>The Relation between Preoperative Polimegathism and the Damage of Corneal Endothelium after PCL Implantation

Corneal endothelial cell damage associated with contact to gas bubbles during YAG laser application.

Corneal endothelial cell damage was generated in freshly enucleated pig's eyes by multiple applications of YAG laser bursts in the anterior chamber focussed 2 mm behind the corneal endothelium. With 100 X 5 bursts at an energy of 5 mJ focussed 2 mm behind the endothelium, a considerable number of gas bubbles were generated at the site of optical breakdown in the aqueous humor. Variable areas of scattered endothelial cell damage or necrosis were observed. By selecting two different experimental settings, a possible harmful effect of the gas bubbles on the corneal endothelium could be demonstrated.

Snailtracks of the Corneal Endothelium

An unusual pattern of corneal endothelial cell alterations has been observed at the slitlamp in eyes following intraocular surgery. Because of their appearance, we have called these changes “snailtracks.” We have commonly seen these snailtracks following extracapsular cataract extraction. Similar changes have been noted in cadaver corneas stored in McCarey-Kaufman (M-K) medium. This study presents information which suggests that these changes represent corneal endothelial cell damage.

Preparation of 2% hydroxypropyl methylcellulose for viscous surgery.

Since 1976 I have used a solution of hydroxypropyl methylcellulose to prevent corneal endothelial damage during intraocular lens implantation. The substance is inexpensive, readily available, and can be easily dissolved. This paper describes preparation of a 2% solution.

Ocular Effect of Neodymium-Yag Laser

We aimed a high-powered pulsed neodymium-YAG laser incrementally from air to the anterior portion of the vitreous in rabbits to evaluate its effect on the corneal endothelium, the lens, and the dynamics of intraocular fluid. Corneal endothelium damage occurred as much as 3.5 mm away from the site of optical breakdown. The degree of tissue damage was inversely proportional to the distance from the site of optical breakdown, and the damage pattern at a given distance was the same whether the optical breakdown was anterior or posterior to the corneal endothelium. A single 4-mJ shot (mode-locked train) of laser light causes disintegration and liquefaction of the lens in a spherical area 300 micron in diameter. The damage extends posteriorly to a distance of 450 micron. The effect of this explosion denatures the surrounding cortical fibers for an area of 50 to 80 micron. Increased intraocular pressure was noted in all instances of anterior or posterior capsulotomy, probably as a result of the release of liquefied cortical material and mechanical obstruction of the chamber angle. No increase in intraocular pressure occurred when the lens capsule remained intact.

Ultraviolet-B damages corneal endothelium.

Direct in vivo observation of acute ultraviolet (UV)-induced corneal endothelial damage is not possible due to the more severe damage produced in the epithelium. In order to quantify damage and evaluate endothelial recovery an indirect method was used. Eyes of pigmented rabbits were irradiated with UV-B (290 to 320 nm) isolated from the output of a high-pressure 1000 W reflectorized Xenon arc lamp by a grating monochromator and appropriate filters. The peak wavelength of the radiation used was 305 nm, with a 18 nm bandwidth at half-maximum. Corneal thickness variations measured with a modified Zeiss (Oberkochen) pachometer were used to follow alterations in epithelial and endothelial function. Epithelial damage alone resulted in a maximum thickness increase of 13.5% within 24 hr with recovery within a further 24 hr. Greater increases in corneal thickness, in the absence of anterior uveal involvement, were taken to indicate endothelial damage, and reached maximum at 2 days, with recovery occurring in 7 days. The threshold for endothelial damage sufficient to disturb corneal deturgescence was 0.12 J X cm-2.

Specular microscopic appearance of damaged and dead endothelial cells in corneas following short-term storage.

Specular microscopic evaluation of rabbit, pig, and cat corneas was performed after storage in a moist chamber in McCarey-Kaufman (M-K) medium or in tissue culture medium 199. Irrespective of the storage method, cooling at 4 degrees C resulted in a deterioration of the specular microscopic image. Most of the changes proved to be reversible if the tissue was quickly rewarmed to 35 degrees C and maintained at that temperature for 20 minutes. One change, dark areas larger than a single cell, was not reversible and increased in prevalence with increased storage time. Trypan blue staining revealed that the dark areas seen with the specular microscope contained damaged endothelial cells. Deep corneal striae tended to increase as the storage interval increased, and considerable cell damage occurred in the endothelium covering these folds. Storage in M-K medium was the most effective of the three methods in preventing deep corneal folds and endothelial damage.

The 'blue eye' phenomenon.

Diffuse clouding of the cornea ('corneal oedema', 'blue eye') of sudden onset and usually transient duration and with accompanying anterior uveitis, may be attributable to natural infection with canine adenovirus type 1 (CA-1) or to vaccination with live modified virus. It is now recognised that kerato-uveitis is a manifestation of type III hypersensitivity in which immune complex formation resulting from the release of virus, especially from infected corneal endothelial cells, brings about corneal endothelial damage and hence corneal oedema. A proportion of cases fail to resolve. At least one breed, the Afghan hound, appears to be particularly susceptible. The incidence of ocular lesions resulting from vaccination has stimulated the development of new vaccines incorporating canine adenovirus type 2 (CAV-2), a serotype which has been shown not be cause endogenous ocular disease.

Corneal Endothelial changes after insertion of iridocapsular (Two-loop) lenses (author's transl)

The corneal endothelial damage in extracapsular extraction and insertion of a two-loop lens (Binkhorst) using the deep chamber technique was investigated by specular microscopy. The endothelial cell loss in 25 patients was 15%. During a mean postoperative period of 15 months a further endothelial cell loss of 5% occurred. The effect of a direct contact between an intraocular lens and the corneal endothelium is demonstrated by a case of luxation of a two-loop lens into the anterior chamber.