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Biomedical subjects

W E Whitson

Publications and source records attributed to W E Whitson.

At least 19 recordsLinked to original sources
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↗
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

Co-management of refractive eye surgery.

An onslaught of publicity about refractive surgery has led to considerable patient interest in this corrective procedure. Regardless of the optometrist's cautious view of refractive surgery, it is here to stay. We may not be providing appropriate care to our patients if we discuss only its disadvantages. It is imperative that we, as primary eye care providers, educate ourselves as to the advantages and disadvantages of refractive surgery so we can better educate our patients. It is our responsibility to help them decide if they are, indeed, candidates for refractive surgery. This paper provides basic knowledge to familiarize the practicing optometrist with radial keratotomy and excimer laser photorefractive keratectomy. Patient selection, preoperative evaluation and counseling, and postoperative care are discussed. Communication between the co-managing optometrist and refractive surgeon is imperative.

Cornea↗
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↗
PubMed1992

Changing trends in explanted intraocular lenses: a single center study.

Over a nine-year period, our practice removed 1,091 intraocular lenses. The most common type of lens requiring explantation was the closed-loop anterior chamber lens (58.6%). The Stableflex lens represented the largest percentage of all removed lens types (28.8%). The number of closed-loop anterior chamber lenses requiring removal peaked in 1988 and then gradually declined. All other lens styles have shown gradually increasing removal rates. Older style iris-fixated lenses and rigid anterior chamber lenses, which have not been implanted for several years, have increasing removal rates. Late breakage of fixational polypropylene sutures with pupil-supported iris-fixated lenses have occurred in five cases; the average time from implantation to suture breakage was 112 months.

Anterior Chamber↗
PubMed1992

Explantation of posterior chamber lenses.

A consecutive series of 119 explanted posterior chamber lenses is reviewed. Seventy (58.8%) were removed because of dislocation or improper fixation, 15 (12.6%) because of anisometropia, and 18 (15.1%) because of chronic inflammation. Sixty-two (52.1%) of these explantations probably occurred for reasons that can be avoided by changes in preoperative, operative, or postoperative techniques. The rate of posterior chamber lens explantations is quite low considering the large number of lenses implanted; with changing surgical techniques, we anticipate that the number of lenses requiring removal will decrease.

Aged↗
PubMed1991

Progression of visual acuity after penetrating keratoplasty.

A consecutive series of 721 eyes was followed for visual acuity changes after keratoplasty in four groups: keratoconus, Fuchs' dystrophy, pseudophakic bullous keratopathy with retained intraocular lenses, and aphakic/pseudophakic bullous keratopathy with secondary implants during keratoplasty. Follow-up ranged from 12 to 84 months. Keratoconus eyes showed the quickest recovery of visual acuity: by 12 months, 91% attained a best-corrected vision of 20/40, and the mean lines of visual acuity for the group plateaued thereafter. The other three groups showed continuing improvement in vision through 24 months. From 3 months through 3 years after keratoplasty, the keratoconus and Fuchs' groups consistently showed better visual acuity levels than either the retained or the secondary implant groups (P less than 0.0001). Reporting changes in visual acuity over time offers multiple advantages compared with providing best-attained or last-recorded visual acuities after keratoplasty.

Adolescent↗
PubMed1991

Graft survival in four common groups of patients undergoing penetrating keratoplasty.

Graft survival rates and causes of graft failure were evaluated for 1046 consecutive keratoplasties in four groups: keratoconus, Fuchs' dystrophy, pseudophakic bullous keratopathy with retained intraocular lenses (IOLs), and pseudophakic/aphakic bullous keratopathy with secondary lens implants. Patient follow-up averaged 23 months (range, 1-84 months). There was a significant difference in graft survival among the four groups, P less than 0.0001. The keratoconus and Fuchs' groups had the highest survival rates and pseudophakic bullous keratopathy with retained IOLs the lowest rate. Problems with the external surface of the graft caused the largest number of graft failures. Grafts for pseudophakic bullous keratopathy with retained posterior chamber lenses had a significantly higher failure rate from rejection and endothelial decompensation, 5.1%, compared with less than 1.0% in keratoconus, Fuchs' dystrophy, or bullous keratopathy with secondary implants (P less than 0.0005).

Adolescent↗
PubMed1990

Natural history of cystoid macular edema in pseudophakic bullous keratopathy.

A retrospective review of 25 consecutive patients having penetrating keratoplasty (PKP) with the preoperative diagnoses of pseudophakic bullous keratopathy (PBK) and cystoid macular edema (CME) was undertaken to analyze the natural history of preoperative CME following keratoplasty. Follow-up ranged from 13 to 54 months with a mean of 27 months. All patients had intraocular lens exchanges with 24 receiving posterior chamber lenses; 23 had lenses sutured to the posterior iris. Sixteen patients (64%) recovered a visual acuity of 20/40 or better. The average time for visual recovery to 20/40 was nine months with a range of two to 45 months. Eighteen (72%) had resolution of angiographic CME. Three patients previously diagnosed as having chronic CME recovered visual acuity of 20/40 or better. Cases of PBK with CME may have an excellent visual prognosis if the IOL is managed properly at the time of PKP.

Aged↗
PubMed1990

Suprachoroidal hemorrhage after placement of a scleral-fixated lens.

Six days after suture-fixation of a posterior chamber lens to the sclera, a suprachoroidal hemorrhage occurred causing pain and intraocular lens dislocation. Placing the sutures at the 3 o'clock and 9 o'clock positions and having the needles exit 2 mm posterior to the limbus may have inadvertently increased the possibility of the hemorrhage. Suprachoroidal hemorrhage after suture-fixating lenses to the sclera and ciliary body area is a potential complication that patients should be advised of preoperatively.

Choroid Hemorrhage↗
PubMed1989

Visual results of suture-fixated posterior chamber lenses during penetrating keratoplasty.

Between August 12, 1982, and June 30, 1987, 233 consecutive eyes had posterior chamber intraocular lenses (PC IOLs) suture-fixated to the posterior aspect of the iris during penetrating keratoplasty (PKP). In all cases, insufficient capsular material was present to provide adequate fixation for the implant. Lenses were placed in 72 aphakic eyes as a secondary implant, and 159 lenses were placed after removal of another implant. Follow-up ranged from 1 year to 68 months with 59.5% of patients achieving visual acuity of 20/40 or better, and 74% of 20/80 or better. Suture-fixating a PC IOL to the iris offers multiple advantages over placement of an anterior chamber lens during PKP. The complication rate appears low, and long-term problems with glaucoma and recurrent corneal decompensation should be reduced.

Aged↗
PubMed1989

Polypropylene ligatures as a means of controlling intraocular pressure with Molteno implants.

A technique for controlling intraocular pressure in the immediate postoperative period with Molteno implants is described. Filtration tubes were closed with polypropylene sutures in 13 patients. Filtration tubes closed with 7-0 sutures provided the most satisfactory partial to complete lumen closure. The ligatures in six patients later were opened by argon laser.

Adolescent↗