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Biomedical subjects

W M Bourne

Publications and source records attributed to W M Bourne.

At least 19 recordsLinked to original sources
PubMed1992

Progression and regression of partial corneal involvement in the iridocorneal endothelial syndrome.

We observed three women with partial corneal involvement in the iridocorneal endothelial syndrome for more than ten years. During this time, the peripheral anterior synechiae progressed in all three, with one patient developing glaucoma. In two patients, the abnormal endothelial cells spread to cover the entire posterior corneal surface; in the third, they disappeared almost entirely. The endothelial permeability to fluorescein remained abnormally low only in the two eyes with diffusely abnormal endothelium, and increased to normal in the third eye as the abnormal endothelium disappeared. The permeability in the third eye had been abnormally low only in the superior half of the cornea, where the abnormal endothelium was located. As the abnormal endothelium regressed, it was replaced by normal endothelium with a normal cell density similar to that of the unaffected fellow eye. Thus, for more than ten years, the partial endothelial involvement associated with the iridocorneal endothelial syndrome progressed substantially in two patients and regressed dramatically in a third.

Adult↗
PubMed1992

Structural and functional studies of the corneal endothelium in diabetes mellitus.

We performed specular microscopy, anterior segment ocular fluorophotometry, corneal pachymetry, and tonometry on 14 patients with chronic type I diabetes and nonproliferative retinopathy and on 14 age-matched control subjects. The eyes of patients with diabetes had an increased coefficient of variation of endothelial cell area, a decreased percentage of hexagonal endothelial cells, increased corneal autofluorescence, and increased intraocular pressure, which confirmed previous studies. There was no difference, however, in corneal thickness or endothelial permeability to fluorescein. Thus, we were unable to detect any abnormality in endothelial function in these diabetic corneas in the unstressed state, despite structurally abnormal endothelial cells.

Adult↗
PubMed1992

A randomized, prospective, double-masked clinical trial of Optisol vs DexSol corneal storage media.

We compared Optisol and DexSol, two chondroitin-sulfate-based media for corneal storage at 4 degrees C, by transplanting 31 donor cornea pairs (one cornea stored in Optisol and its mate in DexSol for 20 to 134 hours) into 31 pairs of recipients (62 patients). All grafts were clear 1 year after transplantation except for one primary donor failure (Optisol group). Optisol-stored corneas were significantly thinner than DexSol-stored corneas after cardinal suture placement (0.64 mm vs 0.76 mm) and at the end of surgery (0.69 mm vs 0.78 mm); at all points afterward through 1 year the two groups did not differ. The activity of two lysosomal enzymes released into the media during storage, alpha-mannosidase and alpha-glucosidase, was lower in the Optisol group. Epithelial status and all endothelial morphometric parameters, except the figure coefficient at 1 year, did not differ between the two groups before surgery and 3, 6, and 12 months after surgery. Mean endothelial cell loss at 1 year was 15% for the Optisol group and 21% for the DexSol group (P = .22). Thus, Optisol-stored corneas were thinner during surgery than DexSol-stored corneas and there was less lysosomal enzyme activity in the Optisol medium after tissue storage. There were no significant differences in postoperative clinical or endothelial morphometric parameters, however.

Adult↗
PubMed1992

Progression and regression of partial corneal involvement in the iridocorneal endothelial syndrome.

We have observed three women with partial corneal involvement in the ICE syndrome for over 10 years. During this time, the peripheral anterior synechiae progressed in all three, with glaucoma developing in one patient. In two patients, the abnormal endothelial cells spread to cover the entire posterior corneal surface; in the third, they disappeared entirely (ie, "the ICE melted"). The endothelial permeability to fluorescein remained abnormally low only in the two eyes with diffusely abnormal endothelium, increasing to normal in the third eye as the abnormal endothelium disappeared. The permeability in that eye had been abnormally low only in the superior half of the cornea, where the abnormal endothelium was. As the abnormal endothelium regressed, it was replaced by normal endothelium with a normal cell density similar to that of the opposite, uninvolved eye. Thus, over a 10-year period the partial endothelial involvement associated with the ICE syndrome progressed substantially in two patients and regressed dramatically in a third.

Adult↗
PubMed1991

Cold-induced corneal edema in patients with trigeminal nerve dysfunction.

Two previous cases of cold-induced corneal edema have been reported in patients with corneal anesthesia secondary to a trigeminal nerve disorder. We studied six patients with complete unilateral corneal anesthesia after trigeminal ablation. Subjects' eyes were exposed to 4 C air from a fan for one hour. We measured corneal thickness, corneal surface temperature, and endothelial permeability to fluorescein. During cold exposure, two of the six study eyes exhibited reversible corneal swelling (11% and 26% over baseline value). All anesthetic corneas were consistently colder (13.8 +/- 0.7 C) than the contralateral corneas (21.0 +/- 1.7 C, P = .001). Baseline endothelial permeability and aqueous humor flow rates were similar in both the study and control groups. After cold exposure, the study eyes had a significant transient increase in permeability compared to the controls (7.5 +/- 2.4 x 10(-4) cm/min vs 2.9 +/- 1.4 x 10(-4) cm/min, P = .007). Baseline endothelial photomicrographs also showed increased pleomorphism (fewer hexagonal cells) in the anesthetic corneas. These data suggest that sensory denervation of the eye influences ocular temperature regulation and corneal endothelial cell morphologic characteristics. Some anesthetic corneas are prone to cold-induced edema, which may result from excessive cooling.

Aqueous Humor↗
PubMed1990

Angiogenic factor: a possible mechanism for neovascularization produced by omental pedicles.

To determine possible mechanisms by which omental pedicles protect bronchial anastomoses from ischemia, we studied the angiogenic potential of a lipid extract of omentum. A rabbit cornea model was used to quantify neovascularization produced by methanol-chloroform extract of homogenized autologous omentum or perirenal fat. In 22 anesthetized rabbits, 10 microliters of omental lipid extract was injected into the cornea. In each animal the opposite eye was used as a control and was injected with a similar volume of extract prepared from perirenal fat. The side of injection of autologous omental fat was randomized and was not known to the investigator who assessed neovascularization on days 4, 7, 14, and 21 after injection. Neovascularization was recorded on microphotography and quantified by a point-counting method. Four days after injection, neovascularization in corneas injected with autologous omental fat was significantly (p less than 0.05) greater than in control corneas for all indices of neovascularization including total point count, which was three times greater than control. The angiogenic effect diminished with time, and by 21 days after injection corneal neovascularization was comparable for the two groups. Our results suggest that the lipid fraction of omentum has angiogenic activity that may stimulate neovascularization in ischemic tissues. Lack of sustained activity may be due to washout by neovessels or local tissue metabolism.

Animals↗
PubMed1990

Effect of silicone elastomer contact lens wear on endothelial cell morphology in aphakic eyes.

We prospectively evaluated the effect of extended silicone elastomer contact lens wear on the endothelial mosaic of aphakic subjects. Endothelial cell photography and central corneal thickness measurements were performed on 23 eyes of 15 aphakic subjects (mean age 60 +/- 10 years). These measurements were made before lens wear (n = 23) and were repeated after 1 year (n = 19) and again after 5 years (n = 10) of lens wear. No statistically significant change in mean endothelial cell size or coefficient of variation of cell size was found. Central corneal thickness was significantly decreased at 1 year and hexagonality was significantly increased at 5 years. Thus, the changes in endothelial morphology usually associated with contact lens wear did not occur with silicone lenses, which are highly permeable to oxygen.

Adult↗
PubMed1989

Corneal topography of early keratoconus.

We used a corneal topography analysis system to evaluate nine eyes of seven patients in whom the diagnosis of keratoconus was suspected. There was no slit-lamp evidence of the condition. In seven of nine eyes a cone was identified. Large amounts of corneal distortion were seen in selected patients even though they had excellent spectacle-corrected visual acuity and little or no distortion of the keratometer mires. These findings suggest that corneal topography analysis systems are useful in the detection and description of corneal irregularity in the early stages of keratoconus. The radial keratotomy surgeon should be aware that normal results on slit-lamp examination and normal keratometry and refractive data do not rule out the presence of early keratoconus.

Adult↗
PubMed1989

Conjunctival deposition of eosinophil granule major basic protein in vernal keratoconjunctivitis and contact lens-associated giant papillary conjunctivitis.

To investigate the role of the eosinophil in vernal keratoconjunctivitis and contact lens-associated giant papillary conjunctivitis, we assessed the presence of eosinophil granule major basic protein in conjunctival tissues by immunofluorescence. Biopsy specimens of conjunctiva were taken from nine patients with vernal keratoconjunctivitis, seven patients with giant papillary conjunctivitis, and five control subjects. We performed a masked semiquantitative assessment of immunofluorescence on sections from each specimen. The vernal keratoconjunctivitis and giant papillary conjunctivitis groups had significantly (P less than .05) more major basic protein deposition than controls. No significant correlation between severity of disease and degree of major basic protein deposition was found. We found extracellular eosinophil granules in one of three vernal keratoconjunctivitis specimens examined by transmission electron microscopy. Thus, eosinophil degranulation commonly occurs in vernal keratoconjunctivitis and giant papillary conjunctivitis with release of eosinophil granule major basic protein and presumably other toxic granule proteins onto affected tissues. These cationic proteins are potent cytotoxins and are able to stimulate mast cell degranulation.

Blood Proteins↗
PubMed1989

Corneal topography of transverse keratotomies for astigmatism after penetrating keratoplasty.

We used a topography system to evaluate retrospectively the pattern of power distribution seen preoperatively and postoperatively in six patients with high postkeratoplasty astigmatism. The relaxing incisions had all been placed based on visual inspection of keratoscope mires alone. Computer analysis of keratoscope photographs showed considerable individual variation in the degree of surface irregularity in preoperative topography. Our data suggest that the steep axis of the postkeratoplasty graft is better conceptualized as two steep hemimeridians. These hemimeridians were separated by an angle other than 180 degrees (two of six cases), and often showed fairly large changes in power from the most central to peripheral areas of the graft analyzed (three of six cases). Asymmetry of power between the two steep hemimeridians was seen in all cases. Areas of maximum steepening were often present in the peripheral portions of the graft in areas other than the major hemimeridians. Individual variation in preoperative corneal irregularity and asymmetry appeared to have an effect on the success of the relaxing incisions.

Adult↗
PubMed1989

Edema of the corneal stroma induced by cold in trigeminal neuropathy.

A patient with a left sensorimotor trigeminal neuropathy was found to have edema of the corneal stroma induced by cold. Examination at room temperature demonstrated an anesthetic left cornea with minimal injection of the left eye and multiple punctate epithelial erosions. Corneal thickness, mean endothelial cell size, coefficient of variation of cell size, endothelial permeability to fluorescein, and aqueous humor flow rate, measured at room temperature were similar in the two eyes. After 47 minutes in a cold room at 4 C, the corneal thickness in the left eye increased from 0.55 to 0.65 mm, whereas that of the right eye remained at 0.55 mm. During the period of maximum swelling, the left cornea had clinical stromal edema with folds in Descemet's membrane but no epithelial edema. After return to room temperature there was a gradual return to normal corneal thickness over three hours. Fluorophotometry showed no evidence of increased endothelial permeability during corneal swelling in the left eye. Specular microscopy after 15 minutes of cold exposure demonstrated many swollen and irregular endothelial cells with darkened areas between cells in the left eye. Sensory nerve deficiency in the human cornea can produce an abnormal sensitivity to cold, resulting in defective control of corneal hydration. This study suggests that this effect may be on the endothelium.

Cold Temperature↗
PubMed1989

A comparison of two preservation media (CSM and K-Sol) by scanning electron microscopy of preserved corneal endothelium.

We compared by scanning electron microscopy the structural preservation of the endothelium of three groups of human corneas after 14 days of refrigerated storage in media, with one eye in K-Sol and the fellow eye in CSM. Each group used a different production lot of CSM and K-Sol. Group 1 comprised ten corneal pairs, and groups 2 and 3 each comprised six corneal pairs. In group 1, K-Sol provided better preservation for each of the ten corneal pairs, but CSM was equal or possibly superior to K-Sol in groups 2 and 3. Variation between different lots from the same manufacturer probably explains the results, which emphasizes the need for consistency in the composition of these preservative media. Large areas of endothelial cell disruption were found in the periphery of the majority of the corneas. Seven of the 44 corneas had no viable endothelial cells. As storage times increase, methods are needed to detect corneas that are not well preserved. We found no consistent differences in the efficacy of corneal preservation between CSM and K-Sol.

Chondroitin↗
PubMed1989

Tolerance of human corneal endothelium to glycerol.

As an initial step in the development of a method for corneal cryopreservation by vitrification, we attempted to establish the maximum concentration of glycerol to which human corneal endothelium could be exposed at 4 degrees C for 15 min without damage. Damage was defined as an increase in mean endothelial cell size or the inability to maintain corneal thickness for 1 week after exposure to glycerol. Using a system for long-term corneal perfusion, we perfused 24 paired human corneas with glycerol at 4 degrees C. The concentration of glycerol increased at a rate of 20% (w/v) (2.2 M) per hour until the desired maximum concentration was reached for that cornea, stabilized for 15 min, and then decreased at the same rate. The corneas were then perfused at 37 degrees C with Dulbecco's medium at a rate of 5 microliters/min under 18 mm Hg intracameral pressure for 7 days with daily measurements of corneal thickness. Endothelial morphology was examined by specular microscopy and by scanning electron microscopy. After 7 days of perfusion at 37 degrees C, there was a statistically significant direct relationship between the maximum concentration of glycerol to which the experimental eyes had been exposed and the increase in mean endothelial cell size. The mean endothelial cell size increased in corneas exposed to glycerol concentrations of 40, 50, and 60% (w/v), but did not differ significantly from baseline measurements in the corneas exposed to 30% glycerol or less. Thus, there was no detectable damage to human corneas exposed to 30% (w/v) (3.3 M) glycerol in this system. Tolerance of higher concentrations may be achieved by changes in the rates of addition and removal of glycerol or in the composition of the perfusate.

Adult↗
PubMed1989

An anatomy of the autopsy, Olmsted County, 1935 through 1985.

In this study, we examined in detail the patterns of autopsy rates for a half century (1935 through 1985) among residents of Olmsted County, Minnesota. The time trend of the autopsy in this community represents, in many respects, a microcosm of national trends. In the process of this analysis, we identified several medical and socioeconomic variables that may influence the rate of autopsy, including the age at death, physical location of death, gender, surgical procedures preceding death, immediate cause of death, and direct and indirect costs of the autopsy. In particular, the advancing mean age at death and the increase of the nursing home as a social phenomenon seem to have had a profound effect on autopsy rates both in Olmsted County and throughout the United States.

Adult↗