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Biomedical subjects

W J Stark

Publications and source records attributed to W J Stark.

At least 55 records · Page 3Linked to original sources
PubMed1994

Recurrent keratoconus.

Keratoconus is a progressive, noninflammatory, nonvascular axial corneal ectasia, with unclear etiology and pathogenesis. It has a prevalence of 50-230 per 100,000 and is a bilateral disorder in up to 90% of cases. The onset of keratoconus is usually at puberty and progresses over 10-20 years producing an irregular myopic astigmatism. The treatment depends on the severity of the irregular astigmatism. Advanced keratoconus, which cannot be treated with contact lenses, requires a surgical procedure--either penetrating keratoplasty, epikeratophakia, or thermokeratoplasty. The results of penetrating keratoplasty are good, with success rates of > 90% of the cases. Recurrence of keratoconus following penetrating keratoplasty has been previously reported, based on a clinical diagnosis, and confirmed by histopathological examination. We report the clinicopathologic features of two further cases of recurrent keratoconus.

Adult↗
PubMed1994

Visual outcome after surgery for Peters' anomaly.

The authors reviewed the charts of 22 patients with Peters' anomaly. Various surgical procedures were performed on 30 eyes of 18 patients (mean number of procedures = 3.3 per eye). Follow-up averaged six years. Visual acuity varied widely, with six eyes having an acuity of 20/400 or better, and 11 eyes with no light perception. Concomitant or secondary glaucoma required a greater number of surgical procedures (4.1 vs 3.4) per eye and was associated with a poorer visual outcome. No eyes with glaucoma had visual acuity better than 20/400. In bilaterally operated patients, visual results in one eye were independent of the outcome of the fellow eye. The range of visual acuity in bilaterally operated patients was similar to the vision in those operated unilaterally. Visual outcome in patients with Peters' anomaly remains guarded. With modern surgical techniques and aggressive attempts at visual rehabilitation, many patients may benefit from surgery. Some patients may have moderately good visual acuity for months or years before vision is lost. In the interim they may learn tasks they may not have otherwise acquired.

Cataract Extraction↗
PubMed1994

Stripping of Descemet's membrane: a clinicopathologic correlation.

We describe a case of accidental injection of sodium hyaluronate (Healon) anterior to Descemet's membrane that caused the membrane to become almost completely detached. The patient eventually underwent penetrating keratoplasty, permitting histopathologic study of the detachment. Sodium hyaluronate globules in the space between the posterior stroma and Descemet's membrane were demonstrated by light and electron microscopy. In addition, 111 consecutive cases of Descemet's membrane detachment identified pathologically were reviewed to identify potential predisposing risk factors and determine corneal pathologic changes. A history of previous intraocular surgery was present in 89 (80%) of the cases; cataract surgery, the most common, had occurred in 52 (58%). Frequent associated corneal pathologic findings were bullous keratopathy in 48 (43%) of the specimens, and scarring and vascularization in 33 (29.7%). In one case that was identified and studied histopathologically, a 90% detachment of Descemet's membrane was noted clinically following the reformation of the anterior chamber with sodium hyaluronate. We conclude that in the cases of Descemet's membrane detachment that came to pathologic examination, intraocular surgery was a major predisposing risk factor. Corneal pathologic changes, which were common, possibly masked the clinical diagnosis of Descemet's membrane detachment in some cases.

Aged↗
PubMed1994

Effectiveness of histocompatibility matching in high-risk corneal transplantation: a summary of results from the Collaborative Corneal Transplantation Studies.

The Collaborative Corneal Transplantation Studies (CCTS) were designed to evaluate the effect of donor-recipient histocompatibility matching and crossmatching on the survival of corneal transplants in high-risk patients. Corneas were allocated to the 419 patients in the double-masked Antigen Matching Study on the basis of HLA-A,-B and HLA-DR antigen match. ABO blood group compatibility was determined but not used for recipient selection. The 37 patients in the Crossmatch Study were randomly assigned to receive a cornea from either a positively or negatively crossmatched donor. All patients received topical steroid therapy according to a standard protocol. Matching for HLA-A,-B and HLA-DR antigens had no effect on overall graft survival, the incidence of irreversible rejection, or the incidence of rejection episodes. The positive group in the Crossmatch Study had fewer graft failures, rejection failures, and rejection episodes than the negative group; however, these differences were not statistically significant. The estimated proportion of eyes with failure from rejection by 3 years was 30% for the ABO-incompatible group and 16% for the ABO-compatible group (relative risk, 1.98; 95% confidence interval, 1.15 to 3.13). These studies demonstrate that, for high-risk patients who are immunosuppressed by topical steroid therapy: 1) neither HLA-A.-B nor HLA-DR antigen matching substantially reduced the likelihood of corneal graft failure; 2) a positive donor-recipient crossmatch did not increase the risk of corneal graft failure; and 3) ABO blood group matching may be effective in reducing the risk of graft failure from rejection.

ABO Blood-Group System↗
PubMed1993

Comparison of acuity, contrast sensitivity, and disability glare before and after cataract surgery.

We assessed vision before and after uncomplicated extracapsular cataract extraction and intraocular lens implantation in 72 symptomatic patients with acuity equal to or better than 20/80 and no other ocular abnormality. Contrast sensitivity was measured with the Pelli-Robson Letter Chart (Metropia Ltd, Cambridge, England) and disability glare was measured under daytime conditions with the Brightness Acuity Tester (Mentor O&O Inc, Norwell, Mass) and under nighttime conditions with a computer-controlled video display. Prior to surgery there was significant disability glare that was not correlated with acuity. There was also a loss in contrast sensitivity that was moderately correlated with acuity (r = -.43; P < .001). Following surgery, most patients' scores returned to normal on all tests. Improvement in disability glare and contrast sensitivity was independent of improvement in acuity. Furthermore, patients with the poorest preoperative vision were as likely to regain normal function after surgery as those with the best preoperative vision.

Adult↗
PubMed1993

Surgical management of subluxed posterior-chamber intraocular lenses.

OBJECTIVE: To formulate a systematic approach to the surgical management of subluxed posterior-chamber intraocular lenses (IOLs). DESIGN: We reviewed the records of 31 consecutive patients who underwent anterior-segment surgery for IOL subluxation. Presumed anatomic causes of IOL subluxation were identified in 28 cases (90%). Three surgical procedures were used to correct the implant subluxation: modified McCannel sutures (19 eyes), IOL exchange (eight eyes), or IOL rotation (four eyes). RESULTS: Twenty-nine (94%) of the 31 patients obtained a postoperative visual acuity of 20/40 or better. Surgical complications included persistent vitreous in the anterior chamber (three cases), progressive capsular opacification (two cases), and anterior chamber and vitreous hemorrhage (one case). CONCLUSIONS: Our results show that, by implementing a planned surgical approach, subluxed posterior-chamber IOLs can be safely and effectively managed.

Aged↗
PubMed1993

High-frequency ultrasound quantitative analyses of corneal scarring following excimer laser keratectomy.

OBJECTIVE: To report objective grading and analysis of excimer laser-induced scarring using high-frequency ultrasound. METHODS: High-frequency ultrasound (50 MHz) corneal examination was performed on eight New Zealand white rabbits at different time points (10, 17, 24, and 74 days following phototherapeutic keratectomy). We used biometry and signal-processing techniques to determine corneal, epithelial, and scar thicknesses and to quantify the acoustic backscatter. RESULTS: Excimer laser-induced scarring showed an irregularly distributed acoustic hyperreflectivity that decreased through day 74. Corneal thickness remained reduced after ablation (mean, 318 microns compared with 419 microns for controls). Epithelial thickness averaged 62 microns and scar thickness, 87 microns. Scar peak and average anterior stroma acoustic backscatter ratios decreased from day 10 to day 74 (19.65 to 2.76, and 6.42 to 1.32, respectively). Histopathologic study showed increased keratocyte activity at early time points that correlated with acoustic backscatter ratios and imaging pattern. CONCLUSIONS: High-frequency ultrasound signal processing is a noninvasive method that quantitatively grades excimer laser-induced corneal scarring.

Animals↗
PubMed1993

Corneal thickness changes after high-risk penetrating keratoplasty. Collaborative Corneal Transplantation Study Group.

OBJECTIVE: To determine whether ultrasonic measurements of corneal thickness are of prognostic value after high-risk penetrating keratoplasty. DESIGN: A prospective, multicenter, randomized trial. PATIENTS: Four hundred fifty patients at high risk for graft failure because of previous immunologic graft failure or because of two or more quadrants of stromal vascularization. Patients underwent surgery and were treated according to a specific protocol and observed at frequent intervals. INTERVENTION: At each postoperative visit, ultrasonic measurement of central corneal thickness was performed and the corneal status was determined by biomicroscopic examination. MAIN OUTCOME MEASURE: Graft failure owing to immunologic or nonimmunologic causes. RESULTS: Corneal thickness stabilized by 3 months at a median thickness of 0.54 mm. The range of corneal thicknesses in patients with corneal grafts judged to be clear was large. In 49% of eyes, development of an allograft reaction episode was accompanied by an increase in corneal thickness of at least 10%; the greater the increase in thickness, the more likely the graft would fail. Clear grafts with central thicknesses of 0.59 mm or greater at 1, 3, or 6 months had a much greater risk of failure than those with thicknesses of less than 0.59 mm. CONCLUSION: Corneal thickness measurements after high-risk penetrating keratoplasty are of prognostic value.

Cornea↗
PubMed1993

Intraocular cilia. Report of six cases of 6 weeks' to 32 years' duration.

In this study, we describe the clinicopathologic features seen in six cases of intraocular cilia and review the features of previously reported cases. Ultrastructural studies of the cilia showed partial loss of the cuticle layer, diffuse accumulation of small electron-dense granules in cuticle and cortical cells, and loss of continuous cell membranes of the cortex. The cilia were almost completely intact in most of our cases. Intraocular cilia can be tolerated for long periods.

Adolescent↗
PubMed1993

Clinical experience with N-butyl cyanoacrylate (Nexacryl) tissue adhesive.

BACKGROUND: To investigate the indications, outcomes, and complications of N-butyl cyanoacrylate tissue adhesive for ocular clinical use. This tissue adhesive is under investigation by the Food and Drug Administration. METHODS: N-butyl cyanoacrylate was used as an investigational device on 44 patients at the authors' institution over a 2-year period. The charts of these patients were reviewed. RESULTS: The indications for glue application included corneal perforation (19 eyes), descemetoceles (9 eyes), leaking filtering blebs (6 eyes), stromal thinning (5 eyes), wound leaks (4 eyes), and exposure keratopathy (1 eye). A bandage contact lens was used over the dried tissue adhesive in 38 of the 44 eyes. Length of glue adherence ranged from 1 to 660 days (mean, 72 days). Outcome was penetrating keratoplasty (19 eyes), no further intervention (14 eyes), enucleation (4 eyes), surgical revision of a filter (2 eyes), scleral patch graft (1 eye), conjunctival transplant (1 eye), failed tarsorrhaphy (1 eye), suturing of wound (1 eye), and a lamellar graft (1 eye). Vision improved in 52% (23/44) of eyes. CONCLUSION: This tissue adhesive may soon be available to all ophthalmologists, and the authors' experience demonstrates that it is an effective method of temporary or permanent closure of an impending or frank perforation.

Adolescent↗
PubMed1993

Oil-drop cataracts.

The oil-drop cataract is a common yet often overlooked cause of progressive vision loss. Although the nuclear change can be subtle on slitlamp biomicroscopic examination, retinoscopy reveals the classic oil droplet silhouetted against the red reflex. We present seven patients with oil-drop cataracts referred for neuro-ophthalmologic evaluation because of unexplained vision loss. All had been evaluated by multiple physicians and had had extensive diagnostic testing. The patients were between 36 and 69 years old with visual acuities from 20/20 to 20/400. The neuro-ophthalmologic evaluation in all patients was normal except for lenticular nuclear changes, best appreciated with retinoscopy.

Adult↗
PubMed1993

Suture abscesses after penetrating keratoplasty.

Eighteen suture abscesses that developed after penetrating keratoplasty in 15 patients were reviewed. The time from keratoplasty to the diagnosis of an abscess ranged from 1 to 53 months with a mean of 21.5 months. In 13 of the 18 cases, the patient was taking topical steroids at the time of diagnosis. All were culture-proven bacterial ulcers, except for one case that had a positive Gram's stain, but no growth on culture. The organisms cultured were Staphylococcus epidemidis (six eyes), Streptococcus pneumoniae (five eyes), Sta. aureus (four eyes), Str. viridans (two eyes), Klebsiella oxytoca (one eye), Serratia marcescens (one eye), Moraxella sp (one eye), and Escherichia coli (one eye). The offending suture was removed in all cases, and the eyes were treated with topical fortified antibiotics (cefazolin and tobramycin). After treatment, 67% (12 of 18 eyes) had clear grafts, 17% (three of 18 eyes) were scarred, and 16% (three of 19 eyes) had failed grafts. Intensive topical steroid therapy was used when a subsequent graft rejection developed. Retained sutures following corneal transplants can result in sight-threatening infections and should be considered for removal as soon as the wound is well healed.

Abscess↗
PubMed1993

Visual function after surgery for early cataract.

Glare disability and contrast sensitivity loss can be present in cataract patients with minimally reduced visual acuity. Objective and subjective visual function was analyzed in 72 patients (mean visual acuity = 20/40) before and after cataract surgery. Following surgery, most subjects regained normal function in all tests. Improvement in contrast sensitivity and reduction of glare disability were independent of preoperative visual acuity. Subjective improvement in visual function was predicted by acuity and contrast sensitivity tests.

Cataract↗