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Biomedical subjects

W J Stark

Publications and source records attributed to W J Stark.

At least 19 recordsLinked to original sources
PubMed1992

Mooren's ulcer and evidence of stromal graft rejection after penetrating keratoplasty.

A Mooren's ulcer developed in a 6-year-old girl after a penetrating keratoplasty for Peters' anomaly. A destructive, circumferential, and centripetal stromal ulceration recurred despite conjunctival resection, corneal gluing, topical and systemic administration of corticosteroids, and repeat graftings. Results of a systemic and a rheumatologic examination were unremarkable. Histopathologic evaluations of donor grafts consistently disclosed a lymphocytic and a plasma cell infiltrate. Indirect immunofluorescent staining using a normal donor cornea substrate was positive at the level of Bowman's membrane and stroma. The patient's lymphocytes were stimulated by a partially purified bovine corneal antigen and a positive antibody titer was found in the patient's sera to the same corneal antigen. These results suggest humoral and cell-mediated immune mechanisms can be involved in the initiation and perpetuation of a stromal rejection process after penetrating keratoplasty.

Cataract Extraction↗
PubMed1992

Rotation of posterior chamber intraocular lenses for management of lens-associated recurring hyphemas.

Management of recurring hyphemas associated with posterior chamber intraocular lenses may include a combination of medical, laser, and surgical modalities. Miotic and laser therapies have often failed, and surgical treatment has primarily relied on removal of the offending lens. We describe herein a method for rotation of the intraocular lens that provides an effective means of preventing one form of recurrent intraocular hemorrhage.

Aged↗
PubMed1992

The effect of early cataracts on glare and contrast sensitivity. A pilot study.

To establish the effect of cataracts on glare and contrast sensitivity, we graded type and amount of lens opacity in 110 subjects who underwent two glare tests (Brightness Acuity Tester and Berkeley glare test) and two contrast sensitivity tests (a sine-wave test and Pelli-Robson chart). Twenty-seven subjects (25%) had clear lenses (mean visual acuity of 20/20) and 83 subjects (75%) had early lens opacities (mean visual acuity of 20/40) in otherwise normal eyes. Multiple regression techniques were used to control for the effects of age and visual acuity. Glare test scores were significantly lower for nearly all patients with lens opacities than for patients with clear lenses and were the lowest for patients with lenses with posterior subcapsular opacity. Contrast sensitivity scores were lower for all patients with lens opacities than for patients with clear lenses at high frequencies only; all lens opacity groups scores similarly with each other. These results indicate reduced visual function among patients with cataracts whose visual acuity is only minimally impaired.

Cataract↗
PubMed1992

Clinical follow-up of 193-nm ArF excimer laser photokeratectomy.

The excimer laser has been undergoing rapid development for clinical use since the early 1980s. The authors report 2-year follow-up results from studies in 31 eyes (15 women and 14 men) to evaluate the excimer laser in performing photokeratectomy. Patients were divided into two groups: 27 eyes (group 1) underwent phototherapeutic keratectomy, and 4 eyes (group 2) underwent photorefractive keratectomy. Visual function improved in 21 of 27 eyes in group 1 and in 2 of 4 eyes in group 2. Complications were minimal and manageable. The authors describe a procedure to minimize induced hyperopia in phototherapeutic keratectomy patients, and, although not statistically significant, less induced hyperopia was noted in these patients. Photokeratectomy may be an alternative to penetrating or lamellar keratoplasty and more invasive refractive procedures, but the long-term effects must be carefully observed.

Adult↗
PubMed1992

Combined trabeculectomy, cataract extraction, and foldable lens implantation.

The efficacy of foldable silicone intraocular lenses in combined glaucoma/cataract surgery was retrospectively analyzed in 19 consecutive operations. Preoperatively all patients were receiving medical treatment for glaucoma; 21% had intraocular pressures above 21 mm Hg despite the medical therapy. Postoperatively, reduction of intraocular pressure to 21 mm Hg or less was achieved in 84% of eyes, with 58% requiring no antiglaucoma medications. Mean improvement of Snellen visual acuity was 4.9 lines; 84% of eyes achieved a final acuity of 20/40 or better. Median follow-up was 59 weeks (range 25 to 88 weeks). Thirteen eyes (68%) had a filtration bleb present when last examined. These preliminary results suggest that foldable silicone IOLs are an effective alternative to poly(methyl methacrylate) lenses in combined glaucoma/cataract surgery.

Cataract Extraction↗
PubMed1992

Worldwide legal requirements for obtaining corneas: 1990.

Cornea transplantation offers the hope of restoring useful vision to millions of individuals worldwide. Yet it is widely used only in certain countries. While a lack of the necessary economic and technical infrastructure is the primary reason in many countries, the legal and social systems pose a similar obstacle in many other more prosperous countries. This article reviews the current laws governing organ and tissue donation throughout the world and distinguishes those that are most successful in obtaining tissue for transplantation.

Cornea↗
PubMed1992

Visual correction following penetrating keratoplasty.

Postoperative visual correction following penetrating keratoplasty usually includes spectacles, but for some patients optimal vision may be obtained using contact lenses. We studied 126 eyes of 101 patients undergoing penetrating keratoplasty to determine the frequency of postoperative contact-lens use, its clinical associations, its effect on the risk of corneal graft rejection, and its potential effects on topical medications. A total of 20 patients (16%) wore contact lenses postoperatively for maximal optical correction. Among eyes with good macular potential, 17 of 63 (27%) wore contact lenses. Contact-lens wear did not preclude the use of chronic postoperative topical medications, nor did it increase the risk of corneal graft rejection. We conclude that contact lenses may be useful for optimizing vision after penetrating keratoplasty, especially when macular potential is good.

Aged↗
PubMed1991

Modulation of corneal wound healing after excimer laser keratomileusis using topical mitomycin C and steroids.

A 193-nm excimer laser system was used to create deep stromal ablations in seven New Zealand white rabbits and shallow ablations in three. Eyes were randomized for treatment with topical mitomycin C, steroids, and erythromycin; topical steroids and erythromycin; or topical erythromycin only. All treatment regimens were instituted twice daily for 14 days. All eyes reepithelialized normally within 3 to 5 days. During 10 weeks of follow-up, all eyes developed moderate reticular subepithelial haze without significant differences among treatment groups. Results of light, fluorescence, and electron microscopic examination showed anterior stromal scarring and markedly reduced new subepithelial collagen formation in the group treated with mitomycin C, corticosteroids, and erythromycin. Focal abnormalities of Descemet's membrane and endothelial abnormalities were present in all treatment groups. Combination therapy with topical steroids, mitomycin C, and erythromycin to control the corneal wound healing response after refractive laser surgery appears promising and warrants further study.

Administration, Topical↗
PubMed1991

Corneal wound healing after 193-nm excimer laser keratectomy.

As part of a human trial of phototherapeutic keratectomy, we performed anterior keratectomy using excimer laser 193-nm ablation on patients with superficial corneal opacities. We examined the ultrastructural changes in the corneas of four patients who underwent penetrating keratoplasty 6 to 15 months after excimer laser ablation. The four cases included macular dystrophy, recurrent keratoconus in a graft, and corneal scarring (two eyes). Light microscopy showed epithelial thickening, absence of Bowman's layer, and superficial stromal scarring in the area of ablation. Ultrastructural study showed that the epithelial basement membrane had focal discontinuities. At the margin of the ablation superficial collagen bundles terminated abruptly in a steplike configuration. The anterior stroma was scarred, with loss of lamellar structure and an increase in number of fibrocytes. The laser-induced scar was 10 to 15 microns thick in the two eyes without a stromal scar before laser ablation. The stroma underlying the scarred areas and that in the untreated area appeared normal. Linear collagen-like fibers were present in the posterior aspect of Descemet's membrane. Laser-induced scarring may be an important factor in limiting visual improvement in patients undergoing phototherapeutic keratectomy.

Adult↗
PubMed1991

Excimer laser ablative treatment of microbial keratitis.

The 193-nm excimer laser was used to ablate experimental septate fungal (Fusarium) and an atypical mycobacterial (Mycobacterium fortuitum) keratitis in an animal model. The infections were allowed to proceed for 24 and 72 hours. After incubation, ablation with a 193-nm excimer laser with 5.0-mm treatment zones was performed until all suppurative areas were treated. The corneas were excised, halved, homogenized, and plated. All cultures were negative in the 24-hour group. However, in those corneas in which the infections were allowed to proceed to 72 hours, post-treatment cultures were positive for both organisms. Histopathologic examination confirmed that 24-hour infections had been eradicated and that 72-hour infections had organisms present. Three of the eight eyes in the M. fortuitum group perforated during treatment, even though the treatment depth by computer preselection was only 150 microns. Excimer laser photoablation may be a useful technique to eradicate early, localized microbial infections. However, it is apparent that advanced infections with deep stromal involvement and suppuration cannot be eradicated using this technique. Because corneas may be perforated inadvertently during treatment, excimer laser treatment of infectious keratitis should be approached with caution and used for superficial and well circumscribed lesions.

Animals↗
PubMed1991

Natural history of corneal astigmatism after cataract surgery.

Little information on the natural course of corneal astigmatism following cataract surgery exists. We report a prospective, computerized analysis of postoperative astigmatism, based on keratometry measurements, of 137 cases of extracapsular cataract extraction with intraocular lens implantation performed by one surgeon. No sutures were cut postoperatively. Surgery induced 1.44 diopters (D) of with-the-rule astigmatism at one month, which declined at a rate of 0.77 D and 0.35 D per month for the next two months, respectively, with a more gradual decline thereafter. The mean surgically induced astigmatism at the last postoperative visit ranged from 0.29 D at six months (minimum follow-up) to 1.23 D at 48 months; both were against-the-rule. Mean follow-up was 28.92 months. These findings may be technique specific and suggest that (1) corneal curvature continues to change slowly even two to four years postoperatively; (2) most patients develop against-the-rule astigmatism, thus more with-the-rule astigmatism is desirable in the early postoperative period; (3) selective suture removal is necessary only when significantly more than 3.00 D of surgically induced with-the-rule astigmatism is present.

Aged↗
PubMed1990

Therapeutic contact lenses.

Therapeutic contact lenses are useful in a variety of ocular surface disorders. Their efficacy was evaluated in 40 consecutive patients presenting for therapeutic contact lens fitting for pain due to depressed surface disorders (14 patients), raised surface disorders (11 patients), corneal decompensation (7 patients), trauma (5 patients), and disorders of corneal wetting (3 patients). The therapeutic contact lens was successfully fit and worn, with achievement of the therapeutic objective in 37 of the 40 patients. Corneal wetting disorders and corneal decompensation require only intermediate-term contact lens wear. Thus, therapeutic contact lenses are usually effective for relief of pain due to corneal surface disorders.

Adolescent↗