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Biomedical subjects

R F Meyer

Publications and source records attributed to R F Meyer.

At least 73 records · Page 4Linked to original sources
PubMed1987

Posterior chamber IOL implantation during keratoplasty for aphakic or pseudophakic corneal edema.

Because of their many advantages, posterior chamber (PC) intraocular lenses (IOLs) were sutured to the posterior iris (in the absence of a lens capsule) in combination with penetrating keratoplasty for aphakic and pseudophakic corneal edema in 53 cases. Secondary PC IOL implantations were performed in aphakic corneal edema (nine cases), and IOLs were exchanged for PC IOLs in pseudophakic corneal edema (44 cases). Ninety-six percent of the grafts remained clear. Forty-three percent of the eyes had 20/40 or better visual acuity, 38% between 20/50 and 20/200, and 19% worse than 20/200, with an average follow-up time of 6.4 (range 3-13) months. The most common cause of poor vision was cystoid macular edema present preoperatively in 20 eyes and postoperatively in 22 eyes. Other causes of persistent visual impairment included macular degeneration (five cases), retinal detachment (two cases), preoperative glaucoma damage (one case), severe postoperative glaucoma damage (one case), endophthalmitis (one case), and graft rejection (one case). Our short-term results indicate that this procedure may be a viable alternative to the use of secondary anterior chamber IOL implantation during penetrating keratoplasty.

Aged↗
PubMed1986

Absence of normal keratan sulfate in the blood of patients with macular corneal dystrophy.

We measured levels of sulfated keratan sulfate in serum using a monoclonal antibody in an enzyme-linked immunosorbent assay. Sulfated keratan sulfate was not detected in the serum of 16 patients with macular corneal dystrophy, but was present at normal levels in 66 patients with other corneal diseases. There were no differences with respect to age, sex, and other ocular findings. This monoclonal antibody recognizes a sulfated carbohydrate epitope present in both corneal and skeletal keratan sulfate. Since most serum keratan sulfate is derived from the cartilages, the defect in keratan sulfate synthesis in macular corneal dystrophy may not be restricted to corneal cells. This assay should prove useful in the diagnosis of macular corneal dystrophy, particularly in children at risk before the appearance of opacification.

Adolescent↗
PubMed1986

Retinal detachment following penetrating keratoplasty.

The time-related risk of retinal detachment during the follow-up of 1146 penetrating keratoplasty procedures was evaluated, using survival analysis techniques. Twenty-eight retinal detachments were observed during follow-up. The Kaplan-Meier estimate of the risk of developing retinal detachment increased from 1.5% at three months to 2.1% at one year after surgery. Further follow-up showed a gradual increase in the cumulative proportion developing retinal detachment to 4.7% at 3.5 years after surgery. Of the preoperative and intraoperative factors available for study, performing an anterior vitrectomy during penetrating keratoplasty was associated with a greater risk of postoperative retinal detachment. The outcome of visual acuity following retinal detachment in these patients' eyes was poor; five patients could not perceive light with the affected eye, and 82% (23/28) had visual acuity of 20/200 or less.

Corneal Transplantation↗
PubMed1986

Corneal hydrops in Terrien's marginal degeneration.

We present four cases of Terrien's marginal degeneration that developed spontaneous ruptures in Descemet's membrane resulting in corneal hydrops. In all cases, the hydrops was characterized by a clear intracorneal pocket of aqueous humor rather than by stromal clouding. In two cases, the pocket extended peripherally to form a conjunctival filtering bleb. Although a lamellar corneal patch graft was used in one case for severe astigmatism, hypotony, and impending perforation, most cases were merely observed without treatment.

Adult↗
PubMed1986

Effect of 1% sodium hyaluronate (Healon) on a nonregenerating (feline) corneal endothelium.

A series of experiments were performed to investigate the effect of 1% sodium hyaluronate (Healon) on the nonregenerating corneal endothelium of the cat. Aqueous humor replacement with 1% sodium hyaluronate resulted in mild, transient elevations of intraocular pressure compared to eyes that were injected with balanced salt solution. Sodium hyaluronate 1% protected the feline endothelium against cell loss incurred by contact with hyaluronate-coated intraocular lenses compared to endothelial contact with lenses that were not coated with sodium hyaluronate. The use of intraoperative 1% sodium hyaluronate, however, did not protect against endothelial cell loss incurred by penetrating keratoplasty or prevent subsequent skin graft-induced corneal homograft rejections. Homograft rejections were milder, however, in some eyes that received grafts coated with 1% sodium hyaluronate. Image analysis of photographs of trypan blue- and alizarin red-stained corneal buttons after trephining, stretching of Descemet's membrane, rubbing against iris-lens preparations, or immediately after penetrating keratoplasty demonstrated that the stretching of the posterior cornea is an important cause of endothelial damage that would not be protected against by a viscoelastic coating.

Animals↗
PubMed1986

Postnatal development of corneal endothelium.

Comparison specular micrographs of infant and adult corneas from cats, cows, dogs, rabbits, and humans demonstrate that a large decrease in central endothelial cell density occurs during maturation of the cornea. Central endothelial cell counts of developing cat, dog, and rabbit corneas decrease rapidly during the first months of life. This rapid decline in endothelial cell density correlates with growth of the cornea to the adult size. Central endothelial cell counts of adult cat, cow, deer, dog, pig, rabbit, and human corneas are similar (2500 cells/mm2) despite a wide variation in corneal size. Comparison of observed endothelial cell counts with two hypothetical situations, one of unrestricted endothelial mitosis and the other of only endothelial hypertrophy, indicates that hypertrophy of individual cells is primarily responsible for achieving the adult cell density of 2500 cells/mm2 for these species. This observation is true for species that have a high adult endothelial mitotic capacity (rabbit) as well as those that do not (cat). The human cornea is a special case because the decline in central endothelial cell density indicates that a large apparent corneal endothelial cell loss (approximately 45%) occurs early in postnatal development.

Adult↗
PubMed1985

Oversized donor grafts in penetrating keratoplasty. A randomized trial.

One hundred seventy-three aphakic or phakic corneal transplants were analyzed in a prospective randomized study to determine the effect of oversized corneal donor buttons on intraocular pressure, corneal curvature and astigmatism, wound dehiscence, and anterior chamber depth. We compared 93 oversized grafts with 80 same-sized grafts. In aphakic eyes, oversized grafts showed a trend toward lower incidence of elevated intraocular pressure during the early post-operative period and lower prevalence of glaucoma at the final visit, although this was not statistically significant. No such trends were seen in phakic eyes. Postoperative corneal curvature was significantly steeper in oversized than same-sized grafts, in both phakic and aphakic eyes; there was no difference in postoperative astigmatism. Anterior chamber depth was significantly greater in oversized grafts. Of four wound dehiscences, all occurred in same-sized grafts.

Aphakia↗
PubMed1985

Sessile macrophages forming clear endotheliumlike membrane on the inside of successful keratoprosthesis.

Clinical observation and cytological study of a successful "through and through" type of Cordona keratoprosthesis, which was removed along with a corneal button about 20 years after its implantation in an aphakic eye, revealed an acellular epitheliumlike film on its outer surface, firm anchoring of its supporting skirt by stable fibrous connections to the stroma, and a continuous separating membrane composed of a homogeneous proteinaceous film with fibroblastlike cells of macrophage origin on its inner surface. The significance of the successful adaptation of the plastic materials of the prosthesis to the tissues of the cornea and the fluid of the inner eye for the future of tissue engineering is discussed.

Cornea↗
PubMed1985

Specular microscopic follow-up of corneal grafts for pseudophakic bullous keratopathy.

Pseudophakic bullous keratopathy (PBK) has become the leading indication for penetrating keratoplasty. In our initial fifty patients having keratoplasty for PBK there was gradual loss of clear grafts in patients with retained intraocular lenses (IOLs). Specular microscopy was performed on donor tissue, and periodically postoperatively, for 130 grafts for PBK. The highest cell loss at one year was in eyes with retained iris support (39.2%) or anterior chamber (37.2%) IOLs. Cell loss in grafts with removed iris support IOLs (21.3%) was significantly less. When iris support IOLs were exchanged for anterior chamber (AC) IOLs, the cell loss at one year (27.1%) was intermediate. We recommend that iris support IOLs be removed at keratoplasty. Exchange for an AC IOL should be considered depending on the visual needs of each patient. Removal of AC IOLs should be based on consideration of prior tolerance and position of the implant.

Aged↗
PubMed1985

Enterobacter cloacae ulceration in a failed corneal graft: a case report.

A 70-year-old female developed a bacterial ulcer in a previously rejected corneal graft. Cultures identified the pathogen as Enterobacter cloacae. Intensive topical antibiotic therapy arrested the progress of the ulcer, and the epithelial defect healed in one week; there was no resultant stromal thinning. Factors which may have predisposed the cornea to ulceration by this organism of relatively low virulence include chronic oedema following graft rejection, topical corticosteroid therapy, and tear insufficiency.

Aged↗
PubMed1985

Surgical treatment of calcific band keratopathy.

A surgical technique utilizing ethylenediaminetetraacetic acid (EDTA) and a Fisch drill with a diamond burr for removal of calcific band keratopathy is presented. Use of a diamond burr is an effective and simple method of removing resistant calcium deposits from the cornea without causing significant scarring.

Adolescent↗
PubMed1985

Reactive membranes on posterior chamber lens implants.

The cytopathology of two types of membranes on surgically removed posterior chamber lens implants is described on the background of the clinical histories. Both implants exhibit film-like proteinaceous capsules with numerous cells of macrophage origin in one case and virtually without cells in the other.

Aged↗
PubMed1984

Classification of corneal endothelial disorders based on neural crest origin.

The corneal endothelium is derived from the neural crest. A general classification of disorders of development of the neural crest has been previously presented (Johnston). Disorders of the corneal endothelium may be considered according to a modification of this scheme to reflect its true embryologic origin. In this classification, corneal endothelial disorders are categorized as abnormalities of neural crest cell formation (cyclopia), migration (Peters' anomaly), proliferation (iridocorneal endothelial syndrome), final differentiation (Fuchs' dystrophy), and acquired abnormalities (metaplasia, abiatrophy, and proliferation).

Adult↗
PubMed1984

Development of a monoclonal antibody capable of interacting with five serotypes of Staphylococcus aureus enterotoxin.

A monoclonal antibody capable of binding to determinants shared in common by staphylococcal enterotoxin serotypes A, B, C1, D, and E was developed. To accomplish this, BALB/c mice were immunized by alternating injections of serotypes A and D to enrich for spleen lymphocytes programmed to produce antibody to possible common determinants. These cells, fused with mutant myeloma cells (P3-X-63Ag8.653) produced hybrids that formed monoclonal antibodies to either serotype A only or to both serotypes A and D. A cloned hybridoma from the latter group produced an antibody (subclass immunoglobulin G1) which interacted with five serotypes. Highest affinity was to B and C1. An immunomatrix consisting of this antibody cross-linked to protein A-Sepharose CL-4B with dimethyl pimelimidate was capable of binding enterotoxin. Bound toxin was eluted with diethylamine. Because of its ability to interact with all five serotypes, the monoclonal antibody should prove useful in the development of a rapid method for screening foods for the presence of staphylococcal enterotoxin.

Animals↗
PubMed1984

Sessile macrophages forming clear endothelium-like membrane on inside of successful keratoprosthesis.

Clinical observation and cytological study of a reasonably successful keratoprosthesis removed along with a corneal button about 20 years after its implantation in an aphakic eye revealed an acellular epithelium-like film on its outer surface, firm anchoring of its supporting skirt by stable fibrous connections to the corneal stroma, and a continuous separating membrane composed of a homogeneous proteinaceous film and fibroblast-like cells of macrophage origin on its inner surface. The significance of the successful adaptation of the plastic materials of the prosthesis to the tissues of the cornea and the fluids of the inner eye for the future of tissue engineering in the region of the eye is discussed.

Cataract Extraction↗