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Biomedical subjects

W J Stark

Publications and source records attributed to W J Stark.

At least 127 records · Page 7Linked to original sources
PubMed1987

Intraocular lens style and refraction in eyes treated with silicone oil.

The comparatively high refractive index of silicone oil significantly alters the refractive power of the human eye when it is placed into the vitreous cavity during retinal reattachment surgery. If cataract extraction and intraocular lens (IOL) implantation are subsequently performed, significant refractive errors result with most IOL styles if standard formulas are used to determine lens power. Thick-lens optical analysis of four IOL styles showed that the meniscus style yields the smallest difference between predicted (Binkhorst, Sanders-Retzlaff-Kraff formulas) and actual postoperative refraction. This IOL style also minimizes the change in refractive error that accompanies subsequent alterations in the contents of the vitreous cavity, including removal of silicone oil and replacement with balanced salt solution.

Eye↗
PubMed1987

Retinal detachment after extracapsular cataract extraction with posterior chamber intraocular lens.

The authors reviewed 3065 consecutive cases of extracapsular cataract extraction with posterior chamber lens implant (ECCE-PC IOL) and found the incidence of retinal detachment to be 1.4% overall (44/3065) and 1.7% in a group of eyes followed for at least 1 year (40/2330). Retrospective analysis of the retinal detachment (RD) group (n = 44) showed the patients to be significantly younger than the overall group (n = 3065) (P less than 0.0001). Comparison with an age-matched group of 302 eyes without RD showed higher rates of RD in males (P = 0.0013) and in eyes with axial eye length (AEL) greater than 25 mm (P less than 0.0001). No significant correlation was found between RD and PC IOL manufacturer, phacoemulsification (PKE), or primary discission. Sixty-four percent of RDs occurred within 1 year of cataract operation. Only 10% occurred more than 2 years later. Visual results in eyes with ultimate anatomic success of RD repair (43 of 44 eyes, averaging 15 months follow-up) are substantially better than previously reported in series with other types of IOLs (96% greater than or equal to 20/40 if the macula was not involved, 75% greater than or equal to 20/40 if the macula was involved).

Age Factors↗
PubMed1987

Cataract extraction after vitrectomy.

Cataract extractions were performed in 25 patients who had previously undergone pars plana vitrectomy. Posterior chamber IOLs were implanted in 20 of 26 eyes. Modification of the usual surgical technique was often necessary because the zonules and/or posterior capsule were unusually mobile. Lens opacities were nuclear sclerotic in 17 eyes (65%) and posterior subcapsular in nine eyes (35%). Visual acuity improved an average of five lines, and final visual acuity was 20/50 or better in 13 eyes (50%). Visual acuity after cataract extraction closely paralleled the best visual acuity after vitreous surgery in all patients. Complications were tears in the posterior capsule in two eyes and postoperative vitreous hemorrhage in one eye. These complications did not limit final vision.

Adolescent↗
PubMed1987

Potential acuity meter for predicting postoperative visual acuity in penetrating keratoplasty. A new method using a hard contact lens.

An irregular corneal surface degrades the optical transmission and limits the effectiveness of the potential acuity meter (PAM) in predicting post-keratoplasty visual acuity. The authors investigated the efficacy of using a temporarily placed hard contact lens to neutralize surface irregularities in conjunction with the PAM in predicting post-keratoplasty visual acuity. A prospective evaluation was performed on 40 keratoplasty patients with a mean follow-up of 10.4 months. Of 27 patients with corneas clear enough to permit them to read letters on the PAM chart, 17 (63%) had very accurately predicted visual acuities by this new method, compared to only eight patients (30%) with the PAM alone. Three patients had predicted visions better than final vision, but this was due to a concurrent cataract in two cases and chronic cystoid macular edema (CME) in the third case. This study indicates that temporarily placing a hard contact lens for use with the PAM can increase its accuracy in predicting final visual acuity after penetrating keratoplasty.

Adult↗
PubMed1987

Current concepts in intraocular lens implantation.

PC IOLs appear to be safe and effective and there are few contraindications. Based on the available data we feel confident about implanting PC IOLs in healthy eyes of patients aged 40 or older. For younger patients, we do not recommended an IOL unless glasses or contact lens use is not feasible. Caution is urged however in the use of semiflexible, closed-loop AC IOLs as well as 'soft' PC IOLs. Other questions regarding material of choice, bag versus sulcus fixation, and UV absorbers remain controversial.

Adult↗
PubMed1987

Treatment of Mooren's and Mooren's-like ulcer by lamellar keratectomy: report of six eyes and literature review.

Three cases of Mooren's ulcer (four eyes) and one case of marginal corneal ulcer associated with relapsing polychondritis (two eyes) are presented with decrease in ocular inflammation following extensive lamellar keratectomy or lamellar keratoplasty. Tissue adhesive was needed in two cases to maintain ocular integrity. The procedure may work by the removal of a corneal antigenic stimulus to a self-perpetrating auto-immune phenomenon that causes corneal melting. More cases are needed to evaluate the therapeutic efficacy of lamellar keratectomy for Mooren's and Mooren's-like corneal ulcers.

Aged↗
PubMed1987

Continuing corneal endothelial loss in intracapsular surgery with and without Binkhorst four-loop lenses: a long-term specular microscopy study.

We analyzed pre- and postoperative corneal endothelial photographs of 17 intracapsular cataract extractions (ICCE) with Binkhorst four-loop intraocular lens (IOL) eyes and found 11.6% mean cell loss at 2 months (previously reported by Hirst et al) increasing to 42.4% after 5 years (p less than 0.05) and 51.8% at 7 years. Eleven ICCE eyes without IOLs similarly examined showed a 15.6% mean cell loss at 2 months (previously reported by Hirst et al), increasing to 33.4% at 5 years (p less than 0.005, paired t-test). Our results appear to indicate long-term continuing cell loss after ICCE, both with and without Binkhorst four-loop iris clip IOLs, and statistically significant greater cell loss (p less than .001, unpaired t-test) with IOLs than without.

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

Surgical vitrectomy for pseudophakic malignant glaucoma.

Four eyes that had undergone cataract extraction with intraocular lens implantation developed malignant glaucoma. Three eyes had posterior chamber lenses and one eye had an anterior chamber lens. Medical therapy was unsuccessful in each case. One eye was treated with Nd-YAG laser disruption of the anterior hyaloid face, but this did not reverse the glaucoma. In all four eyes pars plana vitrectomy reversed the glaucoma process. In the eyes with posterior chamber lenses, the vitrectomy included excision of a localized area of lens capsule and zonules. A pathway for the anterior flow of aqueous was created without dislocating the intraocular lens.

Aged↗
PubMed1986

Reduction of pupillary constriction during cataract surgery using suprofen.

The efficacy of a new nonsteroidal anti-inflammatory agent, suprofen, for reducing pupillary constriction during cataract surgery was ascertained in a double-masked, multicenter, clinical study. Prior to surgery 1.0% suprofen or a placebo was instilled; the surgeon's normal regimen of mydriatics and cycloplegics was used. Suprofen (209 patients) was far more effective than the placebo (203 patients) in maintaining a dilated pupil prior to intraocular lens (IOL) implantation (or instillation of a miotic). The mean pupillary area prior to IOL implantation was 6.3 sq mm larger (20% larger) in patients treated with suprofen than in patients receiving the placebo. The investigators' subjective evaluations of the adequacy of pupil size for IOL implantation and of the difficulty of IOL implantation favored patients treated with suprofen over those receiving the placebo.

Adult↗
PubMed1986

Cataract extraction and intraocular lens implantation in patients with retinitis pigmentosa or Usher's syndrome.

We report the results of cataract extraction in 26 eyes of 16 patients with retinitis pigmentosa or Usher's syndrome. There was no unusual incidence of intraoperative or postoperative complications in this group. After adequate preoperative counseling, and after we made certain that the patients' expectations were in line with anticipated results, 15 of our 16 patients were satisfied with the surgical outcome. Four patients who had a conventional cataract extraction with postoperative contact lens wear in one eye and an intraocular lens implanted in the other eye preferred the eye with the implant. There was no evidence that intraocular lens implantation interfered with the post-cataract-extraction care of the patients.

Adult↗
PubMed1986

Glycolytic activity in the human cornea monitored with nuclear magnetic resonance spectroscopy.

This study confirms the feasibility of using nuclear magnetic resonance (NMR) spectroscopy to assess, noninvasively, glucose metabolism in isolated corneal tissue. Glycolytic activity of human corneas was analyzed by high-resolution NMR spectroscopy and spectrophotometric coupling assays. Glucose utilization and lactate formation were readily demonstrated in incubating intact and deepithelialized human corneas utilizing an NMR spectrometer with an array of spectra taken at ten-minute intervals over a period of nine hours. The lactate formation rate by biochemical coupling assays was determined to be approximately 0.50 mumol/hr in the intact cornea and 0.20 mumol/hr in the de-epithelialized cornea. Analysis by NMR spectroscopy of the rate of glucose utilization and lactate formation may be a useful means of determining human donor corneal viability.

Cornea↗
PubMed1986

Extracapsular cataract extraction and posterior chamber lens implantation in eyes with preexisting glaucoma.

Fifty eyes of 40 patients with glaucoma underwent extracapsular cataract extraction with posterior chamber lens implantation. Their visual results and early postoperative complications were compared with those of eyes in an age-matched group of patients without glaucoma after the same procedure. Substantial increases in early postoperative intraocular pressure (IOP) occurred in 62% of the glaucomatous eyes and in only 10% of the normal eyes. The level of best visual acuity was slightly worse (20/40) on average in the glaucomatous eyes than in the nonglaucomatous eyes (20/25). At six months after surgery, 82.5% of the nonfiltered glaucomatous eyes needed the same number of or additional glaucoma medications to maintain an IOP of less than 20 mm Hg. Ten of the glaucomatous eyes underwent trabeculectomy along with cataract surgery due to inadequate IOP control while the patient was receiving maximum medical therapy. Control was substantially improved, with 100% of these patients receiving the same number of or fewer medications at six months. By one year, only 30% of these patients required the same number of medications postoperatively as preoperatively, but all had IOP control.

Adrenergic beta-Antagonists↗
PubMed1986

Potential acuity meter for predicting visual acuity after Nd:YAG posterior capsulotomy.

We studied 30 patients with opacifications of the posterior capsule to determine if the potential acuity meter (PAM) could accurately predict final visual outcome after Nd:YAG discussion. The final visual acuity was within one line of the PAM prediction in 22 of 30 patients (73%), better by two or more lines in seven patients (23%), and worse in one patient (4%) by two lines. Although in thicker capsules the final acuity was occasionally better than the PAM prediction, the rates of false negative and false positive predictions were very low. Mild cystoid macular edema (3 patients), age-related macular degeneration (3 patients), intraocular lens status, and level of initial acuity did not diminish PAM accuracy. The PAM effectively predicts final visual acuity after YAG posterior capsulotomy, when used in a patient, unhurried manner.

Adult↗
PubMed1986

Macular corneal dystrophy. Lack of keratan sulfate in serum and cornea.

An ELISA assay using a monoclonal antibody (ET-4-A-4) that recognizes a sulfated carbohydrate epitope in both keratan sulfate type I (corneal) and type II (skeletal) was employed to quantify keratan sulfate in serum and corneal tissue from patients with macular corneal dystrophy (MCD). This assay disclosed significant quantities of keratan sulfate in the serum in 45 healthy individuals (251 +/- 78 ng/ml), and in 66 patients with various corneal diseases (273 +/- 101 ng/ml). In contrast keratan sulfate was not detected (less than 2 ng/ml) in the serum of 16 patients with histopathologically confirmed MCD. Keratan sulfate was also detected in extracts of normal corneas and corneal tissue with a variety of pathologic conditions, but was virtually absent in corneal tissue from five patients with MCD. In corneas with MCD the chondroitin sulfate/keratan sulfate ratio was considerably higher than that of all normal and pathologic corneas studied. Since keratan sulfate in the serum appears to be derived predominantly from the normal turnover of cartilage these studies strongly suggest that the defect in keratan sulfate synthesis in MCD is not restricted to corneal cells and that MCD is one manifestation of a systemic disorder of keratan sulfate. The cartilage changes, however, do not have clinical significance. Moreover, since keratan sulfate can be detected in the blood of newborns it should be possible to diagnose MCD prior to corneal opacification.

Antibodies, Monoclonal↗