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Biomedical subjects

F W Price

Publications and source records attributed to F W Price.

At least 19 recordsLinked to original sources
PubMed2001

A prospective, randomized comparison of the use versus non-use of topical corticosteroids after laser in situ keratomileusis.

OBJECTIVE: To evaluate the benefit and safety of topical corticosteroids after laser in situ keratomileusis (LASIK). DESIGN: Prospective, randomized, double-masked clinical trial. PARTICIPANTS: A consecutive series of 1747 eyes in 897 patients desiring surgical correction of myopia from plano to -16 diopters (D) with up to 6 D of astigmatism. INTERVENTION: Patients were randomly assigned to topical corticosteroids or artificial tears. MAIN OUTCOME MEASURES: The primary outcome measure was stability of refraction. Secondary outcome measures were differences in best-corrected visual acuity, decrease in spherical refractive myopia, improvement in uncorrected visual acuity, predictability of achieved corrections versus planned corrections, evaluation of postoperative haze, preservation of best-corrected visual acuity, intraocular pressure, and incidence of complications and adverse events. RESULTS: No difference was found between the groups for refractive accuracy, best-corrected or uncorrected visual acuity, or safety. Topical corticosteroids were associated with a prolonged period of refractive regression in moderate to high myopes (-7.25 to -16.00 D) (P = 0.01). Increased haze was noted at the 1 week examination for eyes not receiving topical steroids (P = 0.008); however, in most cases this was clinically insignificant. Thirty-six eyes (2.1%) required supplemental topical corticosteroids unrelated to reoperation. Two eyes received these on the first postoperative day and 15 at the 1-week examination. CONCLUSIONS: Topical corticosteroids did not seem to play any beneficial role in routine postoperative treatment after LASIK, and they were associated with decreased stability of refraction in more highly myopic eyes. Eyes that require additional topical corticosteroids are easily identified at either the initial postoperative examinations or during the course of routine postoperative care.

Administration, Topical↗
PubMed2001

Viscoelastic material as an adjunct to dissections and to treat microperforations during nonpenetrating filtering surgery.

A case is described in which viscoelastic material was used in the anterior chamber to minimize or prevent fluid flow through the area of the trabecular meshwork and Schlemm's canal during nonpenetrating filtering surgery. In cases with or without small perforations, the technique minimizes or decreases fluid flow so that the surgeon has a clearer view of these tissues and can perform more thorough and accurate stripping of deeper layers of tissue.

Anterior Chamber↗
PubMed2000

Iris fixation of posterior chamber intraocular lenses.

PURPOSE: To describe a technique for suture fixation of silicone intraocular lenses (IOLs) to the iris and compare the outcomes to those in published data. SETTING: Subspecialty cornea/anterior segment private practice, Indianapolis, Indiana, USA. METHODS: This retrospective review comprised 121 consecutive cases of secondary IOL implantation or IOL exchange between 1993 and 1998. All cases had concurrent anterior or posterior vitrectomy. Intraocular lens exchange was performed in 96 eyes, secondary IOL implantation in 20 eyes, and primary IOL implantation in 5 eyes. Penetrating keratoplasty (PKP) was performed concurrently in 93 eyes, extracapsular cataract extraction in 1 eye, intracapsular cataract extraction in 2 eyes, pars plana lensectomy in 2 eyes, and Molteno tube shunt placement for uncontrolled glaucoma in 1 eye. Outcomes measured were graft survival, visual acuity, new onset or worsening of glaucoma, and complications related to surgery. RESULTS: Graft survival at last follow-up was 89.2% in patients having PKP. Visual acuity was 20/80 or better in 58.3% and 20/40 or better in 30.5% of eyes with transplants. Without transplants, visual acuity was 20/80 or better in 82.0% and 20/40 or better in 57.1%. Glaucoma developed or worsened in 24.7% and improved in 16.1% with transplants; it developed or worsened in 7.0% and improved in 17.8% without transplants. Retinal detachment occurred in 1 eye with a transplant. In the nontransplant group, major complications were bullous keratopathy (n = 2) and tilted IOL (n = 1). CONCLUSIONS: Iris fixation of posterior chamber silicone IOLs may decrease the possibility of late suture breakage and dislocation of the IOL, as well as the risk of endophthalmitis. Graft survival, visual acuity, glaucoma, and complications are similar to those of other methods of IOL fixation reported in the literature.

Adult↗
PubMed2000

Trends in the indications for penetrating keratoplasty in the midwestern United States.

PURPOSE: To examine the leading indications and identify the changing trends for penetrating keratoplasty (PKP) in the midwestern United States. METHODS: The indications for PKPs at a single center tertiary care referral practice were tabulated to assess trends from 1982 to 1996. The data analysis was prospective after 1985. Age, gender, clinical indication for PKP, date of surgery, status of the lens at the time of surgery (phakic, aphakic, pseudophakic, cataract), and any secondary diagnoses were recorded. In pseudophakic eyes, the type of intraocular lens (IOL) present at the time of surgery was noted. Correlation analysis and linear regression were used in the SAS system, version 6.12, to test for the statistical significance in increasing or decreasing trends over the span of the study. RESULTS: A total of 4,217 PKPs were performed on 3,263 patients. The leading indication for PKP was pseudophakic bullous keratopathy (31.5%), with 73% of these cases associated with an anterior chamber IOL, 21% associated with a posterior chamber IOL, and 6% associated with an iris-fixated IOL. Fuchs' dystrophy (23.2%), keratoconus (11.4%), corneal scarring (11.2%), failed graft (8.9%), and aphakic bullous keratopathy (7.5%) followed pseudophakic bullous keratopathy in frequency. These six groups accounted for approximately 93% of all cases performed. There were significant increasing trends in the incidence of failed grafts (p = 0.0001) and corneal scarring (p = 0.0001), and decreasing trends in the incidence of aphakic bullous keratopathy (p = 0.0001). There was a significant decreasing trend in pseudophakic bullous keratopathy from 1989 to 1996 (p = 0.0031). CONCLUSIONS: Pseudophakic bullous keratopathy was the leading indication for PKP in our series. This is in agreement with the data reported in other similar studies done in North America. However, unlike most of these studies, our second leading indication was Fuchs' dystrophy. This contrast may be secondary to different genetic demographics in the midwestern United States.

Adult↗
PubMed1999

Effect of astigmatic keratotomy on spherical equivalent: results of the Astigmatism Reduction Clinical Trial.

PURPOSE: To determine the effect of astigmatic keratotomy on spherical equivalent, as measured by the coupling ratio and a new quantity, coupling constant. METHODS: In a prospective multicenter study, subjects underwent arcuate keratotomy at a 7-mm optical zone by means of the Lindstrom nomogram for correction of astigmatism. One hundred fifty-seven eyes of 95 patients who had a follow-up examination 1 month postoperatively were studied. Mean preoperative refractive cylinder +/- SEM was 2.82 +/- 1.17 diopters. Coupling ratio was defined as the ratio of the flattening of the incised meridian to the steepening of the opposite meridian. Coupling constant was defined as the ratio of the change in spherical equivalent to the magnitude of the vector change in astigmatism. Coupling ratio, coupling constant, and change in spherical equivalent were calculated on the basis of change in refraction and keratometry. RESULTS: On the basis of change in refraction, coupling ratio was 0.95 +/- 0.10 (mean +/- SEM) and coupling constant was -0.01 +/- 0.03, consistent with a minor shift in the spherical equivalent of -0.03 +/- 0.07 diopter. On the basis of change in keratometry, coupling ratio was 0.84 +/- 0.05 and coupling constant was -0.04 +/- 0.02, consistent with minor postoperative keratometric steepening of -0.10 +/- 0.04 diopter. Coupling ratio based on change in refraction was not statistically different from the coupling ratio predicted by the Gauss' law for inelastic domes (P = .370). Incision length and number, amount of achieved cylinder correction, age, and sex had no statistically significant effect on coupling ratio, coupling constant, and change in spherical equivalent. CONCLUSIONS: Cornea behaved as an inelastic surface in response to arcuate keratotomy performed with the Astigmatism Reduction Clinical Trial study nomogram. On average, astigmatic keratotomy had a minimal effect on spherical equivalent refraction. There was variability, however, in coupling ratio, coupling constant, and change in spherical equivalent from eye to eye after astigmatic keratotomy. Caution is therefore advised when simultaneous correction of cylinder and spherical equivalent is planned.

Adolescent↗
PubMed1999

Central corneal pachymetry in patients undergoing laser in situ keratomileusis.

OBJECTIVE: To report the preoperative ultrasonic central pachymetric measurements on a large group of eyes undergoing laser-assisted in situ keratomileusis (LASIK) surgery for myopia and myopic astigmatism, to determine whether central corneal thickness is correlated with other geometric features of the eye or is correlated with age or gender, and to discuss the resulting limitations on possible ablation depths. DESIGN: Prospective, multisite, cross-sectional study. PARTICIPANTS: Eight hundred ninety-six eyes in 450 patients from 21 to 66 years of age. MAIN OUTCOME MEASURES: Central corneal thickness and its correlation to intraocular pressure, corneal curvature, axial length, horizontal corneal diameter, refraction, age, and gender. RESULTS: The mean central corneal thickness was 550 microm with a standard deviation of 33 and a range of 472 to 651 microm. The lower 25th quantile was 528 microm. The central corneal pachymetry correlated with the mean manual keratometric measurement (P = 0.0001), simulated keratometry (Sim K) (P = 0.0001), and intraocular pressure (P = 0.0001). Central corneal thickness did not correlate with axial length, age, gender, horizontal corneal diameter, and refraction. CONCLUSION: This clinical study shows there is a substantial range of central corneal thickness in normal myopic eyes. With LASIK, there is a general concern that one should not thin the cornea further than a given amount. Because this study shows wide variability in central corneal thickness, it is prudent to measure pachymetry before surgery and gear treatment plans accordingly. Possible treatment limits relative to corneal thickness are discussed.

Adult↗
PubMed1998

Price graft-over-host technique to manage positive pressure during penetrating keratoplasty.

Intraoperative positive pressure with resulting iris and lens prolapse can pose a difficult scenario during penetrating keratoplasty. In the Price graft-over-host technique, the graft is sutured across the trephinated host cornea, which maintains a formed anterior chamber and thus avoids intraoperative complications. The technique was used in 33 eyes, and no primary or secondary graft failures occurred. Eleven episodes of acute rejection in 11 eyes were treated successfully with steroids.

Adolescent↗
PubMed1998

Management of postkeratoplasty astigmatism.

Many factors have led to the improved success rate for clear corneal grafts after penetrating keratoplasty. Unfortunately, postoperative corneal astigmatism commonly occurs and can produce significant visual impairment. Astigmatic correction may include spectacle correction or contact lenses, but if this fails, then surgical options are considered. Refractive surgical techniques such as suture removal or adjustment, relaxing incisions, wedge resections, and photorefractive keratectomy or laser in situ keratomileusis can dramatically reduce postoperative astigmatism after penetrating keratoplasty and lead to improved, functional vision. However, significant variability between results in individual patients can occur. So although general guidelines are useful, it is important to individualize and modify the planned surgery based on qualitative keratoscopy and corneal topography for the initial and subsequent astigmatic corrections.

Astigmatism↗
PubMed1995

Astigmatism reduction clinical trial: a multicenter prospective evaluation of the predictability of arcuate keratotomy. Evaluation of surgical nomogram predictability. ARC-T Study Group.

OBJECTIVE: To determine the accuracy of the Lindstrom surgical nomogram for astigmatism. DESIGN: A prospective multicenter study. PATIENTS: One hundred sixty eyes of 95 patients underwent astigmatic keratotomy in eight centers by nine surgeons. Inclusion criteria for the study included age of at least 18 years with 1 to 6 diopters (D) of naturally occurring corneal astigmatism and less than 1 D of lenticular astigmatism. INTERVENTIONS: A standardized astigmatic keratotomy surgical technique was performed on each eye. Surgical measurements were determined using the Lindstrom surgical nomogram for astigmatism. MAIN OUTCOME MEASURE: The Holladay, Cravy, Koch vector analysis method was used to determine the change in refractive cylinder results. Refractive changes also are presented without vector analysis merely using the absolute change in refractive cylinder and axis. RESULTS: Multiple regression analysis was used to develop a mathematical model determining the factors predictive of the change in refractive cylinder. The significant predictors for the amount of astigmatic correction achieved were, in order of decreasing importance, the following: number of incisions (R2 = 30%), incision length (R2 = 16%), age (R2 = 8%), and gender (R2 = 2%). CONCLUSIONS: Astigmatism is a two-dimensional measurement of both quantity and direction that is most appropriately analyzed with vector analysis. The original Lindstrom surgical nomogram for arcuate keratotomy used in this study is still quite useful although it tended to underpredict results for many patients, especially those having two incisional surgeries. Some older subjects having minimal surgery achieved greater correction than predicted by the original nomogram. The most important factors predictive of greater astigmatic keratotomy surgical effect are incision number, incision length, older age, and male gender.

Adult↗
PubMed1995

Transscleral fixation of posterior chamber intraocular lenses.

In a retrospective study of 75 consecutive eyes having transscleral suturing of a posterior chamber intraocular lens (IOL) (mean follow-up five months), 57% had improved best corrected visual acuity; 67% of those obtained a visual acuity of 20/40 or better. Thirty-seven eyes had an IOL exchange without penetrating keratoplasty (PKP) at the time of implantation, 15 had simultaneous PKP, and 23 had secondary lens implantation without IOL exchange or a corneal transplant. Transscleral fixation is an effective means of implanting a posterior chamber lens in eyes without capsular support. It allows secure two-point lens fixation with minimal risk of IOL tilting or suture erosion through the conjunctiva or sclera.

Aged↗
PubMed1995

Corneal tissue levels of topically applied ciprofloxacin.

The effectiveness of the fluoroquinolone ciprofloxacin is dependent on stromal drug concentrations which exceed the minimum inhibitory concentration90 (MIC90). The purpose of this study is to compare corneal tissue ciprofloxacin levels in patients exposed to three ciprofloxacin dosing regimens before undergoing penetrating keratoplasty. Thirty-one patients were assigned to one of three treatment groups. Group 1 followed a ciprofloxacin dosing regimen compatible with home use [two drops of 0.3% ciprofloxacin (Ciloxan; Alcon Laboratories, Fort Worth, TX, U.S.A.) every 4 h over a 24-h period]. Groups 2 and 3 followed a more tightly controlled dosing regimen designed for a health-care setting (two drops of Ciloxan applied by a trained professional every 15 min over a 4-h period). In groups 1 and 2, corneal epithelium was left intact, whereas in group 3 corneas were abraded. Corneal tissue samples were surgically obtained. Excised buttons were frozen and Ciloxan concentration determined by high-pressure liquid chromatography. Ciloxan corneal tissue concentrations (mean +/- SD) were 8.82 +/- 8.24 micrograms/g tissue in group 1, 166.20 +/- 336.94 micrograms/g tissue in group 2, and 938.30 +/- 1,081.51 micrograms/g tissue in group 3. Ciloxan penetration can be improved by administering the drug in a controlled setting at 15-min intervals over a 4-h period. Individual Ciloxan concentrations exceeded the MIC90 for most key ocular pathogens despite wide variability in all experimental groups.

Administration, Topical↗
PubMed1994

Intraocular complications associated with the Dubroff anterior chamber lens.

We examined a series of 53 consecutive eyes form which Dubroff-style anterior chamber lenses were explanted. The mean time from implantation to explantation was 46.21 months (range six to 99 months). Problems leading to explantation included bullous keratopathy (83%), glaucoma (51%), chronic cystoid macular edema (40%), and iritis (13%). Molteno valves were required in 9% of eyes. Progressive anterior synechias resulted in intraocular lens displacement against the cornea in 19%. The Dubroff lenses caused problems similar to those previously observed with closed-loop anterior chamber lenses but had a higher incidence of severe glaucoma and progressive peripheral anterior synechias.

Aged↗
PubMed1994

Suprachoroidal hemorrhage in penetrating keratoplasty.

Nine cases of intraoperative expulsive suprachoroidal hemorrhage occurred in a series of 2011 consecutive penetrating keratoplasties (an incidence of 0.45%). In four cases, the complication was directly related to the anesthesia technique. The incidence of hemorrhage was 1.0% in the eyes with preoperative anterior chamber intraocular lenses (IOLs), an incidence significantly higher than for any other associated condition (P < .02). Four of the nine patients recovered a postoperative visual acuity of 20/70 or better. We discuss reasons for the relatively high incidence of hemorrhage during penetrating keratoplasty; its occurrence in relation to the type of anesthesia used, prior intraocular surgery, types of surgery performed together with the penetrating keratoplasty, and the presence of an anterior chamber IOL; and the risks introduced by hemorrhage in a fellow eye and by a previous hemorrhage in the same eye.

Adult↗
PubMed1993

Five-year corneal graft survival. A large, single-center patient cohort.

OBJECTIVE: To determine the survival rates and causes of secondary graft failure in a large, consecutive series of penetrating keratoplasties. DESIGN: All eyes undergoing penetrating keratoplasty at a single center were evaluated for factors relating to penetrating keratoplasty preoperatively, surgically, and postoperatively at 1, 3, 6, 9, 12, 18, and 24 months and then at yearly intervals. Since 1986, data analysis has been prospective. SETTING: A large, private practice, tertiary center for corneal disorders and surgery. PATIENTS: A consecutive series of 1819 penetrating keratoplasties performed from August 1982 through August 1990; 13 eyes with primary graft failure were excluded. MAIN OUTCOME MEASURE: Graft failure and causes of failure. Follow-up ranged from 1 to 96 months, with a mean of 26.6 months. RESULTS: Pseudophakic bullous keratopathy was the most common diagnosis necessitating keratoplasty (38.6%). Secondary failures occurred 111 times (6.1%). The 2- and 5-year survival rates for all grafts in the study were 95% and 91%, respectively. While endothelial failure as a result of immunologic allograft reactions was the most common cause of graft failure (27%), problems with the external surface of the graft caused nearly as many failures (25%). The risk of failure from surface-related problems was highest at 3 months after surgery. There were significantly decreased survival rates for grafts in eyes with regrafts (P < .0001), in eyes left aphakic at keratoplasty (P < .0001), and in eyes with deep stromal vascularization (P < .0001). CONCLUSION: Penetrating keratoplasty is a successful form of transplantation, and survival rates are gradually increasing. The risk of graft failure appears highest within the first year after transplantation.

Adolescent↗
PubMed1993

Intraocular lens exchange for anterior chamber intraocular lens-induced corneal endothelial damage.

BACKGROUND: Anterior chamber and iris-plane intraocular lenses (IOLs) have been implicated in causing corneal endothelial damage and progression to pseudophakic bullous keratopathy. METHODS: The authors performed IOL exchanges on 102 eyes with signs of early corneal decompensation or progressive endothelial cell loss associated with these anterior chamber or iris-plane IOLs. Replacement IOLs were posterior chamber lenses sutured to the iris (87 eyes), sutured to the sclera (3 eyes), or placed in the ciliary sulcus (12 eyes). RESULTS: Seventy-two eyes (71%) had the same or improved vision after a mean follow-up period of 18.6 months (range, 6 to 60 months). Only 24 eyes (23.5%) progressed to corneal decompensation. Of the eyes that decompensated, 75% had preoperative endothelial cell counts of 500 cells/mm2 or less (P < 0.0001), and 83% had preoperative signs of early corneal decompensation (P < 0.001). Biomicroscopic signs of early corneal decompensation seen preoperatively in 50 eyes resolved in 17 eyes (34%) and remained unchanged in 12 eyes (24%) at the last postoperative follow-up visit. CONCLUSION: Removal of anterior chamber and iris-plane intraocular lenses in eyes showing signs of endothelial damage may prevent progression to pseudophakic bullous keratopathy if performed before a critical degree of endothelial cell loss or dysfunction has developed.

Aged↗
PubMed1993

Expression of cell adhesion molecules in corneal graft failure.

Corneal graft failure is frequently mediated by uncontrolled inflammatory disease. We studied the expression of cell adhesion molecules in seven penetrating keratoplasty specimens with graft failure and in a normal eye bank cornea using immunohistochemical staining and monoclonal antibodies against intercellular adhesion molecule-1 (ICAM-1, CD54), lymphocyte function-associated antigen-1 (LFA-1, CD11a/CD18), vascular cell adhesion molecule-1 (VCAM-1), E-selectin, and major histocompatibility complex (MHC) class II antigen (HLA-DR). ICAM-1 and HLA-DR were expressed on keratocytes and the corneal endothelium in six of the seven specimens. ICAM-1 expression was strongest in the corneas with the most severe inflammation (corneal allograft rejection and severe intraocular inflammation). LFA-1 is a counter-receptor for ICAM-1, and infiltration with leukocytes expressing either the alpha or beta chain of LFA-1 was found in areas of ICAM-1 expression in four of the seven corneas. In contrast, E-selectin was expressed in the stroma in only two specimens, and VCAM-1 in one specimen. Expression of cell adhesion molecules or MHC class II antigen were not detected in the normal eye bank cornea. These data suggest that ICAM-1 expression may play an important role in the development of corneal graft failure. Furthermore, monoclonal antibodies to block ICAM-1 or its ligands may inhibit the development of corneal inflammation.

Antibodies, Monoclonal↗