Henry F. Edelhauser

THE EFFECTS OF SODIUM HYALURONATE, CHONDROITIN SULFATE, AND METHYLCELLULOSE ON THE CORNEAL ENDOTHELIUM AND INTRAOCULAR PRESSURE

Sodium hyaluronate (Healon), chondroitin sulfate, and methylcellulose have been used to protect the corneal endothelium from intraocular lens trauma. A study of the efficacy and toxicity of these compounds showed that 1% sodium hyaluronate, 0.4% methylcellulose, and 20% chondroitin sulfate were nontoxic to the corneal endothelium, but that 20% chondroitin sulfate caused a marked decrease in corneal thickness because of its hypertonicity. Anterior chamber injection of these viscous substances resulted in an increase in intraocular pressure. Within one to four hours the maximum intraocular pressure with 1% sodium hyaluronate was 67 +/- 4.1 mm Hg and that with 20% chondroitin sulfate was 55 +/- 3.5 mm Hg. The intraocular pressure did not increase to these high levels with 10% chondroitin sulfate or 0.4% methylcellulose or when the test substances were washed out of the anterior chamber. The corneal endothelium was protected from injury with 1% sodium hyaluronate and 20% chondroitin sulfate, but 10% chondroitin sulfate and 0.4% methylcellulose provided only minimal protection.

Effect of Epinephrine on the Corneal Endothelium

Intracameral epinephrine has been advocated for treatment of iris bleeding and inadequate pupillary dilatation during intraocular surgery. Commercial epinephrine 1:1000 with its preservative sodium bisulfite damaged corneal endothelial function and ultrastructure in rabbit and monkey eyes with sodium bisulfite the source of the damage. Endothelial damage can be prevented with a 1:5000 dilution of commercially available epinephrine in 0.1% sodium bisulfite or freshly prepared epinephrine bitartrate 1:1000 with a bicarbonate Ringers.

Endothelial Degeneration and Posterior Collagenous Proliferation in Aphakic Bullous Keratopathy

In series of 39 corneal grafts, aphakic bullous keratopathy comprised 13 (33%) of the cases. By scanning and transmission electron microscopy, endothelial degeneration and posterior collagenous proliferation were consistent features. In all 13 cases, the patchy loss of endothelial cells occurred diffusely over the entire posterior corneal surface. The remaining endothelial cells had become extremely attenuated to increase their surface area. In nine cases, acellular proliferations of collagenous tissue were interposed between the endothelial cells and Descemets membrane. These posterior collagenous layers were composed of collagen fibrils and basement membrane material, randomly arrayed in a feltwork of uniform thickness; they appeared ultrastructurally identical to those encountered in a variety of conditions involving endothelial distress.

Ultrastructure of the primary spectacle and cornea of the sea lamprey

Ultrastructural features of the primary spectacle and cornea of the sea lamprey (Petromyzon marinus) are described. The epithelial cells of the spectacle contain two distinct areas of cytoplasm. The stroma of the spectacle consists of 40 collagen lamellae interconnected by sutural fibers. These sutural fibers appear to prevent the stroma of excised spectacles from swelling in deionized water. Stromal cells lie between the collagen lamellae. A monolayer of flat cells and its basement membrane cover the posterior surface of the spectacle. A thin mucoid tissue which separates the spectacle from the cornea contains fibrillar and amorphous substances. The cornea consists of regularly arranged collagen lamellae enclosed by monolayers of flat cells and their basement membranes. The endoplasmic reticulum of the cells in the anterior monolayer of the cornea is highly developed. Terminal bars were not observed between the membranes of the cells in the three monolayers.

Development of cornel transparency in embryonic chick: Influence of exogenous thyroxine and thiouracil on structure, water and electrolyte content ☆

Abstract Thiouracil and thyroxine (T 4 ) were injected onto the chick chorioallantois at various developmental stages to study their effects on corneal cellularity, dehydration and structure. Corneas were excised 2–9 days after treatment for histological examination and for analyses of water content, sodium concentration [Na + ] and potassium concentration [K + ]. Untreated chick corneas showed that water content and [Na + ] decreased with advancing embryonic age, while [K + ] increased up to stage 42 and then rapidly declined. Corneas from embryos injected with 10 mg thiouracil at stage 36 had a significantly reduced [K + ] at stages 40 and 42. Corneas at stages 40, 42 and 45 had a significantly elevated water content when compared with controls. Injection of 15 μg of T 4 prior to stage 36 or at or after stage 40 did not produce significant changes in corneal water and ionic content compared with controls; injection of 15 μg of T 4 during the cell proliferation period of corneal development (stages 36–40) produced a significant increase in [K + ]. Similar results were obtained in corneas from embryos injected with 1 μg of T 4 . Total corneal thickness was increased in thiouracil treated corneas, and decreased in T 4 treated corneas. Epithelial growth was markedly decreased with thiouracil treatment, while T 4 had little effect. It is likely that thiouracil treatment decreases cell division in the cornea, and prevents formation of the epithelial barrier, whereas T 4 accelerates these processes.

Uptake and removal of dimethyl sulfoxide in rabbit and human corneas during cryopreservation

Abstract The uptake of DMSO by the cornea does not reach equilibrium during 40 min of incubation in the cryoprotective solutions which precede controlled rate freezing of the tissue. A postthaw incubation in 25% albumin for 10 min at 4 °C removed 65% of the DMSO. The residual DMSO within the cornea diffuses into the aqueous humor following transplantation. Residual DMSO can be removed from the cornea prior to transplantation by increasing the time of postthaw incubation in the albumin solution or by incubation in Kinsey medium.

The effect of cryoprotection and cryodamage on corneal rehydration and endothelial structure

Abstract Corneal rehydration rate and endothelial ultrastructure were compared during postthaw perfusion of cryopreserved corneas and corneas that had been frozen and thawed without the benefit of cryoprotective solutions. The postthaw swelling rate of cryopreserved rabbit corneas was 171 μm/hr compared to 333 μm/hr in the cryodamaged corneas. Most of the endothelial cells were intact in the cryopreserved corneas, but the intercellular spaces were enlarged. In contrast, all of the endothelial cells in the cryodamaged corneas were disrupted and Descemets membrane was only partially covered by the remaining cell fragments.

Ultrastructural changes associated with loss of transparency in the primary spectacle and cornea of spawning sea lamprey

Abstract Structural changes associated with loss of transparency in the nonswelling primary spectacle and cornea of the sea lamprey during spawning were studied by electronmicroscopy. Epithelial cells of the spectacle were separated by enlarged extracellular spaces, while the stroma of both the spectacle and cornea was found to be invaded by leukocytes. Collagen break-down and the presence of electron-dense amorphous and filamentous material were observed in the superficial stroma.

A comparative study of stromal swelling in sea lamprey spectacle and brook trout cornea

Brook trout corneal stroma immersed in water increased to 350 % of its original wet weight; whereas, the stroma of sea lamprey spectacle which contains sutural fibers increased to only 150 %. The normal arrangement and spacing of collagen fibrils was preserved in the stroma of the sea lamprey spectacle. In contrast, in the osmotically swollen brook trout corneas, large interlamellar spaces were present which contained fragments of lysed keratocytes. Control stromal tissues from both sea lamprey spectacle and trout cornea placed in 0.5 % saline showed small changes in wet weight and maintenance of normal collagen alignment. The sutural fibers present in the sea lamprey spectacle appear to prevent stromal hydration by opposing the osmotic swelling of the stromal cells, thereby limiting the development of interlamellar spaces and preventing the loss of transparency.