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Biomedical subjects

W J Stark

Publications and source records attributed to W J Stark.

At least 145 records · Page 8Linked to original sources
PubMed1986

Clinical and immunological results of corneal allograft rejection.

Of 111 episodes of graft rejection in 66 patients, 62 responded to therapy with graft clearing (responders); 49 did not (non-responders). Both groups were of similar age, sex, and etiology; both had a similar rate of glaucoma and a similar rate of previous grafting. In responders the graft reaction was shorter in duration (2.2 vs. 5.6 wks. p less than 0.005), and it was necessary to increase the number of glaucoma medications more often in non-responders compared to responders (41% vs. 19%, p less than 0.02). The interval from surgery to reaction was similar in responders and non-responders (18.2 vs. 13.3 mos., p greater than 0.1). An epithelial rejection line was present in 11% of responders, but was not present in non-responders (p less than 0.05). Lymphocytotoxic antibody development correlated with rejection in 16 of 64 episodes. Patients who responded to treatment were more frequently asymptomatic (p less than 0.05) or were treated earlier following the onset of symptoms compared to non-responders (p less than 0.0001).

Adult↗
PubMed1986

A case of epithelial ingrowth primarily involving the lens capsule.

We describe an unusual case of epithelial ingrowth primarily involving the lens capsule. Four years following removal of the lens and epithelial tissue the eye was quiet with 20/20 acuity. Histopathology showed intraocular epithelium attached to the anterior surface of the lens capsule.

Adult↗
PubMed1986

A computerized analysis of astigmatism after cataract surgery.

We have performed a computerized analysis of postoperative changes in corneal astigmatism in 203 consecutive cases of extracapsular cataract extraction with posterior chamber intraocular lens implantation performed by one surgeon. Surgical technique was standardized consisting of a 140 degree posterior limbal incision with preplaced 9-0 silk and postplaced 10-0 nylon sutures. The average postoperative astigmatism was 1.60 D and the average surgically induced change in astigmatism 0.51 D after a mean follow-up of 5.4 months. When the axis of astigmatism was considered, cataract surgery on the average initially induced 2.2 D of with-the-rule astigmatism which gradually declined, stabilizing at 0.35 D against-the-rule 19 weeks postoperatively. An analysis of the natural history of astigmatism after cataract surgery helps to optimize the timing of spectacle prescription and postoperative intervention to correct excessive astigmatism. A computerized astigmatism analysis also provides rapid feedback to guide changes in surgical technique to minimize astigmatism.

Astigmatism↗
PubMed1985

The Honan intraocular pressure reducer. An experimental study.

Although use of the Honan intraocular pressure reducer is believed to be clinically safe and effective in reducing IOP and the risk of vitreous loss, the IOPs achieved during application of the device have not been directly measured. Intraocular pressure dynamics in ten eyes of five patients were measured shortly after death, using a pressure transducer within the anterior chamber as the Honan device was applied. Pressures were measured again after enucleation. The peak IOPs produced in eyes in situ were much lower than in the same eyes after enucleation. The peak IOP increased as the initial IOP was raised. The Honan device would appear to be safe for eyes undergoing routine anterior segment surgery, but the pressures that may be generated in hypertensive eyes (IOP greater than or equal to 35 mm Hg) might put these eyes at risk for vascular occlusion.

Adult↗
PubMed1985

Topical retinoid treatment for various dry-eye disorders.

We evaluated the clinical efficacy of treating various dry-eye disorders using 0.01% and 0.1% (weight/weight) topical all-trans retinoic acid ointment. Twenty-two patients were selected and classified into four major groups: keratoconjunctivitis sicca (6 patients; 11 eyes), Stevens-Johnson syndrome (9 patients; 17 eyes), ocular pemphigoid or drug-induced pseudopemphigoid (3 patients; 6 eyes), and surgery or radiation-induced dry eye (4 patients; 4 eyes), based on the criterion that they remained symptomatic even under maximum tolerable conventional medical and/or surgical therapies. The results indicated that squamous metaplasia with mucin deficiency secondary to goblet cell loss and keratinization may be the basis for the development of clinical symptoms and morbidities, as these epithelial abnormalities were invariably present before treatment. After treatment, all patients demonstrated clinical improvements in symptoms, visual acuity, rose Bengal staining, or Schirmer test. Most importantly, this topical vitamin A treatment caused the reversal of squamous metaplasia as evidenced by impression cytology. Therefore, this treatment may represent the first nonsurgical attempt to treat these disorders by reversing diseased ocular surface epithelium.

Administration, Topical↗
PubMed1985

Tissue toxicity of laser-damaged intraocular lens implants.

Because of close proximity to the posterior capsule, the posterior chamber intraocular lens is frequently damaged when capsulotomy is performed using the Nd:YAG laser. Damage to the optic or haptics of an intraocular lens may release substances potentially toxic to intraocular tissues. We found that injection molded intraocular lenses experimentally damaged using multiple YAG laser burst at energy levels of 10 mJ or greater released compounds which caused cell death to cultures of human conjunctival epithelial cells, retinal pigment epithelial cells, choroidal cells, and retinoblastoma cells. No cytotoxic effect was seen at energy levels of 2 and 5 mJ.

Cataract Extraction↗
PubMed1985

Neodymium: YAG lasers. An FDA report.

Analysis of data from four neodymium:YAG laser manufacturers submitted to the Food and Drug Administration (FDA) on over 17,000 cases indicate the procedure is safe and effective for cutting opaque posterior lens capsules. A successful opening in the pupillary membrane was achieved in 98% of the cases, and vision improved in 84% of the cases. Clinically significant risks include: a rise in intraocular pressure two to four hours after treatment, damage to the intraocular lens, and rupture of the anterior hyaloid face.

Humans↗
PubMed1985

Immunology of corneal allograft rejection. Associated human leucocyte populations.

Human serum samples and peripheral blood mononuclear leucocytes (PBML) were collected from ten corneal transplant recipients over a two-year period at intervals before and after surgery, and during and after episodes of immunologic (rejection) reaction. Serum was monitored for the development of antibodies to histocompatibility antigens and PBML were stained with a panel of monoclonal reagents specific for T cell and for monocyte populations using indirect immunofluorescence. Patients who demonstrated an elevation in the Leu 2a+ (suppressor/cytotoxic) T cell population following an immunologic reaction ultimately accepted their grafts, whereas patients whose Leu 2a+ population was unaffected developed irreversible graft clouding. Additionally, a direct positive correlation between the development of elevated levels of lymphocytotoxic antibodies and helper T cells was noted in some patients during immunologic reactions. Neither DR-positive nor monocyte population changes demonstrated any consistent correlation with rejection episodes or final graft outcome.

Adult↗
PubMed1985

Corneal alpha-galactosidase deficiency in macular corneal dystrophy.

Glycosidases, which cleave sugar molecules from complex glycopolymers, have been previously quantified in normal human cornea in our laboratory. Data quantifying glycosidases in macular corneal dystrophy are lacking. Tissue obtained at keratoplasty from patients with macular dystrophy and normal corneas obtained from eye bank eyes were used to determine levels of glycosidase activity. A fluorometric technique was employed using 4-methyl-umbelliferyl-glycosides as substrates. The corneal tissues were homogenized, centrifuged, and the supernatants assayed for enzyme activity. Specific activities (mumol/mg protein/hour) were determined and Km and Vmax values were obtained for all but one enzyme. Activity of alpha-galactosidase was significantly lower in cornea tissue and keratocytes from macular corneal dystrophy compared to normal.

Cornea↗
PubMed1985

Immunology of corneal allograft rejection: HLA-DR antigens on human corneal cells.

Human stromal and endothelial cultures were established from corneas obtained from the Maryland Eye Bank. Cultures were incubated in the presence of human gamma interferon for 4 days, trypsinized, washed, and then stained with a monoclonal reagent specific for human Class II (HLA-DR) antigens. Under these conditions, 100% of human corneal endothelial cells and 40 to 70% human corneal stromal cells expressed HLA-DR antigens.

Cornea↗
PubMed1985

Argon laser debridement of the posterior capsule: a potential treatment for posterior capsule opacification after extracapsular cataract surgery.

We treated an opacified membrane on the anterior surfaces of the posterior capsule of two cynomolgus monkeys that had undergone extracapsular cataract extraction and intraocular lens insertion. After development of opacification of the posterior capsule, argon laser energy was employed in an attempt to debride the capsules while maintaining structural integrity of the capsule. With this technique, small areas of destruction of the membrane on the anterior surface of the posterior capsule were created with preservation of the capsule.

Animals↗
PubMed1984

Anterior corneal mosaic in eyes with keratoconus wearing hard contact lenses.

The anterior corneal mosaic is the pattern produced by massage of the cornea through the closed eyelids following the instillation of fluorescein sodium. This pattern has been observed without lid manipulation in eyes with keratoconus wearing hard contact lenses. Thirty-three (75%) of the 44 eyes with keratoconus wearing hard contact lenses spontaneously demonstrated the presence of the anterior corneal mosaic pattern; the pattern occurred spontaneously in two (5%) of 40 eyes in the control group of normal corneas. The mechanism by which the anterior corneal mosaic pattern is produced by hard contact lens wear provides an explanation of the high incidence of this pattern in eyes with keratoconus wearing hard contact lenses.

Adolescent↗
PubMed1984

Cystoid macular edema in pseudophakia.

Cystoid macular edema after cataract surgery, with or without intraocular lens implantation, has been reported to develop in more than 50% of patients as detected by fluorescein angiography. It is associated with reduced visual acuity in up to 8% of cases. Analysis of ongoing clinical trials at the Wilmer Institute indicates that clinically significant cystoid macular edema develops in a lower percentage of cases (2% total incidence and 0.3% persistent cystoid macular edema) if the intraocular lens implantation was uncomplicated. The factors associated with cystoid macular edema and the importance of considering clinically significant rather than just fluorescein-proven cystoid macular edema are discussed. Results of intraocular lens studies reported to the Federal Drug Administration are updated, and results of an ongoing study of prostaglandin inhibitors at the Wilmer Institute are reported.

Aged↗
PubMed1984

Posterior capsule opacification: a specular microscopic study.

Posterior capsule opacification following extracapsular cataract extraction is a manifestation of migration of lens epithelial cells onto the posterior capsule. Collagen production by these epithelial cells results in white "fibrotic" opacities. These cells have myoblastic features and their contraction produces wrinkling of the posterior capsule resulting in visual distortion. A high magnification, in vivo specular microscopic study of human posterior capsules following extracapsular cataract extraction is described. In vivo findings correlate with histopathologic observations made on opacified posterior capsules. Lens epithelial cells migrate onto the posterior capsule and produce basement membrane and collagen. Collagen production is associated with a spindle-shaped appearance of the hyperplastic cells. This technique is useful for clinical research on posterior capsule opacification, including the evaluation of interventions designed to treat or prevent this complication.

Adult↗