Biomedical subjects

Charlotte E Joslin

Publications and source records attributed to Charlotte E Joslin.

8 recordsLinked to original sources

PubMed2006

Baseline factors predictive of incident penetrating keratoplasty in keratoconus.

PURPOSE: To identify baseline demographic and clinical factors associated with undergoing penetrating keratoplasty (PK) in a prospective cohort of 1,065 keratoconus patients followed for eight years in the Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study. DESIGN: Multicenter, prospective, observational cohort study. METHODS: We report the rate of PK over eight years and baseline factors predictive of PK in 1,065 patients who, at the time of study enrollment, had not undergone PK in either eye. RESULTS: Eighty-two percent of patients completed the eight-year close-out visit. Twelve percent (126 of 1,065) had PK in one (9.3%) or both eyes (2.5%). Baseline factors associated with increased likelihood of PK included younger age, steeper keratometric values, worse visual acuity, corneal scarring, poorer contact lens comfort, and poorer vision-related quality of life. The percent of eyes undergoing PK was 15% for patients 40 years old and younger, 28% for eyes with a steep keratometric value greater than 52 diopters, 33% for visual acuity less than 20/40, and 24% for eyes with corneal scarring. CONCLUSIONS: The CLEK Study confirmed previous reports of the increased likelihood of PK associated with corneal scarring, steeper keratometry values, poorer visual acuity, and poorer contact lens comfort. The CLEK Study is among the first to report an increased risk of PK associated with younger age, worse vision-related quality of life, and flatter contact lens fits. Knowledge of these factors is beneficial to clinicians in patient education and may be useful in disease management.

Adolescent↗

PubMed2006

Epidemiological characteristics of a Chicago-area Acanthamoeba keratitis outbreak.

PURPOSE: To characterize Acanthamoeba keratitis (AK) cases and analyze the geographical distribution within the Chicago-Gary-Kenosha metropolitan area, Chicago, Illinois, USA. DESIGN: Retrospective, population-based cohort study. METHODS: All AK cases diagnosed at the University of Illinois at Chicago Cornea Service from June 1, 2003, to November 30, 2005, were included in analysis. Patients with keratitis were defined as cases through confocal microscopy, histology, and/or positive cultures. Exploratory analyses were performed to evaluate whether AK cases were unequally distributed geographically. County population data were extracted from US Census 2000 data, and rates were age-standardized to Cook County. Poisson regression analysis was used to estimate the age-standardized rate ratio (RR) between AK cases and county of residence. Current cases (June 1, 2003 to November 30, 2005) were compared with historical cases (June 1, 2000 to November 30, 2002) to determine if the current rate of AK diagnosis differed from historical rates. RESULTS: Forty AK cases were diagnosed between June 1, 2003 and November 30, 2005. The average (+/-SD) age of patients with AK was 28.0 +/- 15.0 years (range, 13 to 70 years), 52.5% were men, and 95.0% wore contact lenses. Estimated RR measures demonstrated increased rates for all counties relative to Cook, and were significant for both DuPage County (RR 3.59; 95% confidence interval [95% CI] 1.44, 8.39) and Will County (RR 3.66; 95% CI 1.18 to 9.56). Current AK diagnosis rates were significantly higher than historical rates (RR 6.67; 95% CI 3.05 to 17.52). CONCLUSIONS: AK cases are increasing in frequency. The increased rates are unevenly distributed in the study area. Further research is warranted to better understand the increase and unusual geographical distribution.

Acanthamoeba Keratitis↗

PubMed2005

Contact lens overrefraction variability in corneal power estimation after refractive surgery.

PURPOSE: To evaluate the accuracy and precision of the contact lens overrefraction (CLO) method in determining corneal refractive power in post-refractive-surgery eyes. SETTING: Refractive Surgery Service and Contact Lens Service, University of Illinois, Chicago, Illinois, USA. METHODS: Fourteen eyes of 7 subjects who had a single myopic laser in situ keratomileusis procedure within 12 months with refractive stability were included in this prospective case series. The CLO method was compared with the historical method of predicting the corneal power using 4 different lens fitting strategies and 3 refractive pupil scan sizes (3 mm, 5 mm, and total pupil). Rigid lenses included 3 9.0 mm overall diameter lenses fit flat, steep, and an average of the 2, and a 15.0 mm diameter lens steep fit. Cycloplegic CLO was performed using the autorefractor function of the Nidek OPD-Scan ARK-10000. Results with each strategy were compared with the corneal power estimated with the historical method. The bias (mean of the difference), 95% limits of agreement, and difference versus mean plots for each strategy are presented. RESULTS: In each subject, the CLO-estimated corneal power varied based on lens fit. On average, the bias between CLO and historical methods ranged from -0.38 to +2.42 diopters (D) and was significantly different from 0 in all but 3 strategies. Substantial variability in precision existed between fitting strategies, with the range of the 95% limits of agreement approximating 0.50 D in 2 strategies and 2.59 D in the worst-case scenario. The least precise fitting strategy was use of flat-fitting 9.0 mm diameter lenses. CONCLUSIONS: The accuracy and precision of the CLO method of estimating corneal power in post-refractive-surgery eyes was highly variable on the basis of how rigid lense were fit. One of the most commonly used fitting strategies in clinical practice--flat-fitting a 9.0 diameter lens-resulted in the poorest accuracy and precision. Results also suggest use of large-diameter lenses may improve outcomes.

Adult↗

PubMed2004

Is "whole eye" wavefront analysis helpful to corneal refractive therapy?

PURPOSE: To examine how corneal refractive therapy (CRT) affects the balance between corneal surface and whole eye spherical aberration (Z4) and to identify whether corneal aberrations alone can accurately predict optical outcomes of CRT. METHODS: Whole eye and corneal spherical aberrations were measured at baseline and 1 month after CRT in 12 dilated eyes (baseline myopia range, -2.25 to -6.00 diopters [D]; mean, -3.23 +/- 1.06D). Whole eye aberrations were measured under cycloplegia using a Shack-Hartmann aberrometer, and corneal aberrations were measured using Keratron corneal topography elevation maps converted to wavefront Zernike polynomials using VOL-CT. Whole eye and corneal surface aberrations were scaled for 6-mm pupil diameters. RESULTS: No statistically significant correlation existed between corneal and whole eye spherical aberration at baseline. Corneal and whole eye spherical aberration increased in all eyes after CRT. A statistically significant and moderately positive correlation was found between corneal and whole eye spherical aberration after CRT (R = 0.632, P = 0.004). The linear regression slope was positive (m = +1.449) and indicated that whole eye spherical aberration exceeds corneal spherical aberration after CRT. CONCLUSIONS: Whole eye wavefront analysis is essential to methods designed to optimize visual performance with CRT; results indicate that CRT affects the entire optical system and not just the anterior corneal surface. Moreover, because CRT-induced whole eye spherical aberration cannot be explained by corneal aberrations alone, commonly accepted beliefs that the mechanism of action is limited to corneal tissue redistribution may need to be revisited.

Adult↗

PubMed2004

Characteristics of corneal ectasia after LASIK for myopia.

PURPOSE: There are numerous reports of corneal ectasia after laser in situ keratomileusis (LASIK) for myopia without a consistent definition of this condition or a definitive etiology. We conducted a retrospective analysis of published case reports to describe common characteristics of this postoperative event and compared them with findings from a group of successful LASIK patients. METHODS: A MEDLINE search for "LASIK" and "ectasia" yielded 21 relevant articles published before May 2003 (n = 86 eyes, 59 patients). A comparison group (n = 103 eyes, 63 patients) was selected from a clinic-based sample of successful LASIK patients with 12 months of follow-up after treatment. Descriptive statistics are reported as median and interquartile range. Comparisons were performed using the Wilcoxon rank sum, Wilcoxon signed rank, and chi-square tests. RESULTS: Time to diagnosis of ectasia after LASIK was 13 months (6 to 20 months). Residual myopia in the ectasia group was -3.69 D (-6.00 to -2.13 D) and was significantly greater than the comparison group, -0.38 D (-0.75 to 0.00 D), P < 0.001. After surgery, eyes with ectasia had increased corneal toricity 2.87 D (2.00 to 4.9 D) with increased oblique astigmatism 1.3 D (0.23 to 2.89 D) relative to eyes in the comparison group 0.00 D (0.00 to 0.08 D), and a loss of 2 lines (-0.5 to -6 lines) of best spectacle-corrected visual acuity (all P < 0.001). Thirty-five percent of reported cases resulted in subsequent corneal transplantation. CONCLUSIONS: Preoperative characteristics of corneal ectasia include worse visual acuity, less corneal thickness, greater residual myopia, and greater corneal toricity than nonectatic eyes. Treatment factors associated with corneal ectasia after LASIK are greater stromal ablation and less residual stromal bed thickness. Postoperative characteristics of corneal ectasia are myopic refractive error with increased astigmatism, worse spectacle-corrected visual acuity, increased corneal toricity with topographic abnormality, and progressive corneal thinning.

Adult↗

PubMed2003

Higher-order wavefront aberrations in corneal refractive therapy.

PURPOSE: To assess the changes in higher-order (third through sixth) ocular wavefront aberrations produced by Corneal Refractive Therapy (CRT; Paragon Vision Sciences, Mesa, AZ). METHODS: Eighteen eyes of nine myopic subjects were fit with CRT contact lenses. Baseline subjective spherical refraction ranged from -2.25 to -6.00 D (mean +/- SD, -3.33 +/- 1.26 D), and baseline logarithm of the minimum angle of resolution (logMAR) best-corrected visual acuity was -0.13 +/- 0.06 (20/15 Snellen equivalent). Whole-eye ocular wavefront aberrations were measured using a previously validated Shack-Hartmann aberrometer. Measurements were taken at baseline and 1 month after treatment initiation. Nine measurements per dilated subject were taken and averaged. Zernike coefficients were used to calculate the third-, fourth-, fifth-, and sixth-order root-mean-square values for each eye for both 3- and 6-mm pupil sizes, and aberrations were averaged and compared with prior baseline readings. RESULTS: The mean (+/-SD) myopia reduction was 3.08 +/- 0.93 D, resulting in a subjective refraction of -0.22 +/- 0.38 D after 1 month of lens wear. Both logMAR uncorrected visual acuity (-0.07 +/- 0.18; 20/15- Snellen equivalent) and best-corrected visual acuity (-0.14 +/- 0.09) after CRT wear were not significantly different from baseline logMAR best-corrected visual acuity (paired two-tailed t-test; p = 0.41 and 0.65, respectively). Whole-eye aberrations showed a statistically significant increase in higher-order aberrations for both 3-mm (factor of 2.66; p = 0.01) and 6-mm pupils (factor of 2.50; p = 0.005). Each individual higher-order aberration also increased, ranging from a factor of 2.01 to 3.20 for 3-mm pupil sizes and 2.52 to 2.98 for 6-mm pupil sizes. Spherical-like aberrations (S4 and S6) increased by a factor of 1.79 for 3-mm pupil sizes and 2.42 for 6-mm pupil sizes. The Zernike coefficient most affected by CRT was spherical aberration (Z40), which increased from 0.084 +/- 0.16 to 0.39 +/- 0.16 microm (p = 0.0002) for 6-mm pupils. CONCLUSIONS: Use of current CRT lenses for the reduction of myopia increased higher-order wavefront aberrations and spherical aberration (Z40) in particular.

Adult↗

PubMed2002

Between-eye asymmetry in keratoconus.

PURPOSE: To report baseline differences between eyes on key variables in the Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study cohort compared with a retrospectively assembled group of myopic contact lens wearers without ocular disease. METHODS: A total of 1,079 keratoconus patients who had not undergone a penetrating keratoplasty in either eye before their baseline visit were enrolled and examined at baseline. Records from 330 contact lens-wearing myopes were reviewed. Corneal curvature (keratometry), visual acuity, refractive error (manifest refraction), and corneal scarring were measured. RESULTS: The mean differences between keratoconic eyes are as follows (better eye-worse eye for each variable, separately). Flat keratometry: -3.59 +/-4.46 D and steep keratometry: -4.35 +/-4.41 D; high-contrast best-corrected visual acuity: 7.30 +/-6.83 letters; low-contrast best-corrected visual acuity: 8.53 +/-7.51 letters; high-contrast entrance visual acuity: 9.03 +/-8.40 letters; low-contrast entrance visual acuity: 9.43 +/-7.88 letters; spherical equivalent refractive error: 3.15 +/-3.84 D; and refractive cylinder power 1.55 +/-1.42 D. Twenty-one percent of the keratoconus patients had corneal scarring in only one eye. There is an association between patient-reported unilateral eye rubbing and greater asymmetry in corneal curvature, and between a history of unilateral eye trauma and greater asymmetry in corneal curvature and refractive error, with the rubbed/traumatized eye being the steeper eye most of the time. CONCLUSIONS: Keratoconus is asymmetric in the CLEK Study sample.

Adult↗

PubMed2002

The effectiveness of occluder contact lenses in improving occlusion compliance in patients that have failed traditional occlusion therapy.

PURPOSE: Management of infants and young children with dense amblyopia, including that which results from unilateral congenital cataracts, is challenging because of noncompliance with occlusion therapy. Occluder contact lenses (OCLs) have been described to successfully improve visual acuity in patients with amblyopia. The purpose of this study was to evaluate the effectiveness of OCLs in improving occlusion compliance in infants and young children with dense amblyopia who had failed traditional occlusion therapy. METHODS: Thirteen patients were fit in their nonamblyopic eye with OCLs provided by Wesley Jessen (Des Plaines, IL). All patients had dense amblyopia as diagnosed by a pediatric ophthalmologist. Nine of the 13 patients had deprivational amblyopia associated with unilateral aphakia, 2 patients had strabismic amblyopia, and the other 2 had mixed mechanism amblyopia. All patients had failed traditional occlusion methods. Occlusion was prescribed on a part-time basis to prevent occlusion amblyopia to the better-seeing eye. Compliance with the OCLs was determined by questioning the parents as to whether the prescribed occlusion time was accomplished. RESULTS: Five of the 13 patients (38.4%) did not succeed in the initial 1-mo trial period because of parental difficulties with lens handling. Four patients (30.7%) achieved partial success, as they were able to wear the lens between 4 to 14 mo, at which time they learned to remove the occluder lens. The four remaining patients (30.7%) successfully wore the occluder lenses until the conclusion of the study, a time period ranging from 26 to 60 mo. No complications resulted from OCLs. CONCLUSIONS: OCLs can provide an alternative to achieving occlusion compliance after the failure of traditional occlusion therapy in infants and young children with dense amblyopia.

Amblyopia↗