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Biomedical subjects

W D Mathers

Publications and source records attributed to W D Mathers.

At least 55 records · Page 3Linked to original sources
PubMed1991

Vortex keratopathy of the corneal graft.

We examined the surface epithelium of 30 eyes with color specular microscopy at 3-month intervals 1-18 months following penetrating keratoplasty. At least three examinations were performed on most eyes. We found a vortex keratopathy to be present in 70% of these eyes. In nine eyes, this vortex pattern was present at every examination, and in 12 eyes, it was present at some examinations and not at others. There was no vortex pattern seen at any examination in nine eyes. We also found alterations in the normal epithelial morphology around sutures and at the wound margin, with palisading parallel to the sutures and perpendicular to the wound edge. This altered morphology was also demonstrated by digitization of cells for shape and size, which showed significant differences compared with normals. We conclude that the morphology of the epithelial cells on the surface of the cornea remains abnormal for up to 18 months following penetrating keratoplasty.

Cell Movement↗
PubMed1991

Corneal steepening with final suture removal after penetrating keratoplasty.

We reviewed 53 patients after they underwent penetrating keratoplasty, comparing the change in average corneal curvature before and after final suture removal 15-18 months postsurgery. In 29 eyes with keratoconus, there was a significant increase in average curvature of 3.48 diopters +/- 3.76 (p less than 0.0005). In 24 eyes with other diagnoses, there was also a significant increase in the average curvature of 3.26 diopters +/- 3.98, (p less than 0.0005). The difference between these groups was not significant. The amount of steepening correlated negatively (-.6494) with the average corneal curvature before suture removal (p less than 0.005). We found no change in the average astigmatism after suture removal; however, large changes in astigmatism occurred unpredictably with some patients. This study shows that corneal curvature after penetrating keratoplasty steepens after suture removal, particularly in flat corneas, and astigmatism may shift unpredictably.

Adult↗
PubMed1991

Meibomian gland dysfunction in chronic blepharitis.

We examined 57 patients with symptoms of chronic blepharitis using meibomian gland expression, meibography, tear osmolarity, and the Schirmer's test. We also performed meibography on 20 normal patients free of chronic blepharitis. We found that 42 blepharitis patients (74%) had evidence of meibomian gland loss, whereas only four of 20 normal patients (20%) had any gland dropout. We performed cluster analysis on the data from the patients with blepharitis and found that these patients tended to fall into distinct groups with clinically relevant characteristics. We also found that tear osmolarity correlated positively with gland dropout (+0.413) and negatively with excreta volume (-0.499). This study demonstrates that an objective analysis of meibomian gland function may be used to assess chronic blepharitis and define subsets of blepharitis with measurable differences. It also supports the significance of meibomian gland dysfunction on tear osmolarity and the evaporative state of the eye.

Adult↗
PubMed1991

Meibomian gland morphology and tear osmolarity: changes with Accutane therapy.

We evaluated the meibomian gland function of 11 patients before and during treatment with isotretinoin (Accutane) by assessing tear osmolarity, meibomian gland morphology, tear production, rose bengal staining, and meibomian gland excreta. We found, during Accutane use, that meibomian glands appeared significantly less dense and atrophic by meibography. Excreta thickness increased from 1.7 +/- 0.9 to 3.1 +/- 1.2 (p less than 0.005), and expressible excreta volume decreased from 1.52 +/- 0.68 to 1.10 +/- 0.3 (p less than 0.05) (scale 1-4). We also found a significant increase in tear osmolarity from 304.9 +/- 11 to 316.3 +/- 10 mosmol/L (p less than 0.005). There was no significant change in the Schirmer test during treatment. We suggest that the clinical symptoms of blepharitis during Accutane therapy are related to decreased meibomian gland function and consequent increased tear evaporation and tear osmolarity.

Acne Vulgaris↗
PubMed1991

Surgical treatment for a case of postoperative Pseudallescheria boydii endophthalmitis.

Pseudallescheria boydii (P. boydii) is an uncommon ocular pathogen which previously has been identified in only 10 of 905 fungal isolates identified by the Sid Richardson Microbiology Laboratory at the Cullen Eye Institute of Baylor College of Medicine. Furthermore, only one case of postoperative P. boydii endophthalmitis and four cases of endogenous P. boydii endophthalmitis have been reported. Three of the four patients with endogenous endophthalmitis died within 4 weeks of diagnosis. We describe a second case of postoperative endophthalmitis due to this fungus. The infection was successfully eradicated following vitrectomy, corneoscleral resection, and patch graft, in addition to intraocular, topical, and oral antifungal medication. Although in vitro sensitivities are variable, P. boydii is known to be relatively resistant to amphotericin B. This points to the importance of proper cultures and sensitivities when treating cases of suspected fungal endophthalmitis. Unfortunately, the patient's eye became phthisical 6 months following the initial intervention.

Aged↗
PubMed1989

Corneal epithelial cell movement in humans.

Evidence is presented which supports the centripetal movement of epithelial cells in the normal corneal epithelium. This movement is not, however, uniform and is influenced by various factors including corneal topography, surface disease states and lid shearing forces. We have studied epithelial morphology with corneal specular microscopy and have demonstrated altered morphology in keratoconjunctivitis sicca, neurotrophic keratitis, and contact lens wearing. Following penetrating keratoplasty, we found a vortex keratopathy in 70 per cent of patients up to two years after surgery. We also found pallisading of epithelial cells around sutures which indicated centripetal movement of epithelial cells around islands of stability created by obstructions. The eyelid also alters epithelial migration and turnover by increasing exfoliation from shearing forces. We advance a new hypothesis that the driving force in the central epithelial cell movement is the preferential loss of surface cells by exfoliation from the central apex secondary to the shearing forces of the upper lid.

Cell Movement↗
PubMed1989

Surface cell morphology of the anesthetic human cornea: a color specular microscopic study.

The technique of color specular microscopy has been utilized to study the surface cell morphology of the human cornea in 6 subjects with profound corneal anesthesia from diverse causes. In an analysis of cell area, perimeter, and shape, anesthetic corneas showed a statistically significant increase in cell size and perimeter. In addition, there was a loss of cellular outlines and overall increase in rose bengal staining of cells. We believe that these cellular microscopic changes reflect profound changes in epithelial cell turnover related to a decrease in neurohumoral transmitters known to be necessary for maintenance of normal corneal morphology and function.

Adult↗
PubMed1989

Dose-dependent effects of epidermal growth factor on corneal wound healing.

The dose-dependent effect of epidermal growth factor (EGF) on the development of wound tensile strength following full-thickness corneal wounds was evaluated in 60 adult rabbits. One eye from each rabbit received a single 7-mm long corneal incision. After injury each rabbit was treated three times daily for 5 or 10 days with either EGF at 0.001 mg/ml (10 eyes), 0.01 mg/ml (10 eyes), 0.1 mg/ml (10 eyes), 1.0 mg/ml (15 eyes), or vehicle (15 eyes). The tensile strength of the wound was evaluated using a 5-mm wide strip of cornea mounted on a tensiometer. We found that EGF at 0.1 mg/ml and at 0.01 mg/ml increased wound strength by 100% at 5 days and by 60% at 10 days (P less than 0.05 and P less than 0.05). However, EGF at 0.001 mg/ml and 1.0 mg/ml appeared to have no effect on wound strength. Histologic examination of full-thickness wounds in a separate series showed an increase in wound fibroblastic response and a diminished fibrin clot at 5 days in rabbits treated with 0.1 mg/ml and 0.01 mg/ml. We conclude that EGF enhances the wound strength of full-thickness corneal wounds in a dose-dependent manner which may be explained in part by an increased fibroblastic response. Concentrations of EGF greater or less than an optimal dose may be less effective in enhancing corneal wound strength.

Administration, Topical↗
PubMed1988

Return of human corneal sensitivity after penetrating keratoplasty.

To evaluate the reinnervation of corneal grafts, we studied 91 eyes of 79 patients for the return of sensitivity one month to ten years following penetrating keratoplasty for various corneal disorders including keratoconus, Fuchs' dystrophy, herpes simplex keratitis, aphakic and pseudophakic bullous keratopathy, glaucoma, trauma, and interstitial keratitis. Using the Cochet-Bonnet esthesiometer, a sensation was recorded in the center of the graft no earlier than 18 months. We found a progressive return of sensitivity from the periphery toward the center of the graft. Regression analysis indicated a rate of return of sensitivity that averaged 0.029 mm/mo for each diagnostic category except herpes simplex keratitis. The slope of the return of sensitivity in the group with herpes simplex keratitis was essentially flat, showing no central progression. None of the eight patients with herpes simplex keratitis had a sensation recorded further than 0.5 mm from the wound margin.

Cornea↗
PubMed1987

Corneal rim cultures.

We performed a retrospective analysis of 291 consecutive scleral rim cultures, taken at the time of corneal transplantation, from 1981 to 1986. There were 82 positive cultures (39%), and the most common pathogen was Staphylococcus epidermidis, with 24 positive cultures (30%). Ten of these (42%) were resistant to gentamycin. There were no cases of endophthalmitis or other infections in the immediate postoperative period. We also found 15 positive cultures of Streptococcus viridans. Of these, 13 (87%) were resistant to gentamycin but sensitive to most other antibiotics. Even though endophthalmitis is rare following penetrating keratoplasty, the emergence of resistant strains of Streptococcus viridans and Staphylococcus epidermidis suggests that eyebanks need to consider the addition of a second antibiotic to their MK medium.

Cornea↗
PubMed1980

A bioassay for a water-soluble benzodiazepine against sodium thiopental.

The authors performed a bioassay of midazolam maleate, an investigational, water-soluble benzodiazepine; to determine the duration of sleep after a single intravenous dose. Sodium thiopental was the standard against which the midazolam maleate was assayed. Prior to operation 60 surgical patients were randomly given one of five doses of drugs, either thiopental, 180 or 270 mg, or midazolam maleate, 6.6, 10, or 15 mg. The designated drug was infused intravenously over 20 sec in a double-blind fashion. Sleep was defined as commencing when the patients stopped counting, and ending when they could respond appropriately to verbal commands. Midazolam maleate, 10 mg (9--12 mg represents 95 per cent confidence limits), was found to be equivalent to thiopental, 200 mg, in the duration of sleep induced. Apnea following the infusion was less frequent and of shorter duration after midazolam maleate than after thiopental. It is concluded that midazolam maleate is a satisfactory agent for the induction of anesthesia, and that it is about 20 times as potent as thiopental.

Adolescent↗