Biomedical subjects

T B Edrington

Publications and source records attributed to T B Edrington.

10 recordsLinked to original sources

PubMed1997

Efficacy of hand washing procedures on bacterial contamination of hydrogel contact lenses.

The effect of various hand washing regimens on transfer of bacterial contaminants from the hands to a hydrogel contact lenses was evaluated. Each of 47 subjects performed 5 different hand washing procedures, and then handled a new, sterile hydrogel contact lens. The lenses were cultured to determine colony-forming units (CFUs) and microbial identity. Median CFUs on lenses handled after washing with water, soap and water, or soap and water followed by towel drying were higher than the median CFU for lenses handled after no hand washing. The median CFU for lenses handled after soap and water washing followed by an alcohol wipe was not different from the no washing group. The majority of the contaminants were identified as Staphylococcus epidermidis. These results show that ordinary hand washing alone does not decrease, and may even increase, the amount of contaminants transferred from the hands to a hydrogel lens. Use of an alcoholic wipe after hand washing reverses this effect. Hand washing is still recommended in contact lens hygiene for removal of more pathogenic contaminants.

Colony Count, Microbial↗

PubMed1996

Biomicroscopic signs and disease severity in keratoconus. Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study Group.

The Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Survey represents the largest sample of clinic-based keratoconus patients to date. Data were collected at 38 clinical centers on 1,579 keratoconus patients. This article reports demographic variable, ages, self-reported ages at diagnosis, keratometry, slit-lamp findings, systemic disease, family history of keratoconus, and best spectacle-corrected and contact lens-corrected visual acuity of this sample group. The average age of this clinic-based sample group was 37 years (range 10-89 years), with 84% between 20 and 49 years old. Thirteen percent of patients had unilateral keratoconus, defined as unilateral corneal irregularity. More advanced disease (steeper average keratometric reading) was associated with a greater likelihood of Vogt's striae, Fleischer's ring, and/or corneal scarring. Fifty-eight percent of the eyes in this group of patients had > or = 20/40 visual acuity with manifest refraction. Penetrating keratoplasty was reported in 12.3% of eyes. This prospective survey identifies the associates between the presence of Vogt's striae, Fleischer's ring, and/or corneal scarring and increasing steepness, as measured by keratometry.

Adolescent↗

PubMed1996

Characteristics of corneal staining in hydrogel contact lens wearers.

Corneal fluorescein staining is widely used in clinical practice and research, but little information exists on the distribution of staining in a large group of asymptomatic contact lens wearers. This cross-sectional study took place at 3 centers, and investigated the pattern of corneal fluorescein staining in both eyes of 98 hydrogel contact lens wearers. We also investigated the strategies used by three experienced clinicians to grade corneal staining. Overall corneal staining was graded using a scale from 0 to 4 in one-half steps, and five corneal zones, superior, inferior, nasal, temporal, and central, were also graded. The average overall staining grade for both eyes of our subjects was 0.50, with an average of 0.57 for the right eye and 0.44 for the left. This difference between the eyes was statistically significant (p = 0.011). In addition, a comparison of the zones within each eye showed a significant difference (p = 0.0001) among the zones. Corneal staining between the two eyes was also positively and significantly correlated (r = 0.58; p = 0.0001). Grading strategies among clinical investigators were significantly different (p = 0.0001), indicating a potential source of bias in multi-centered studies. The difference in corneal staining between the eyes may represent a source of systematic bias, and could be due to grading the right eye before the left. The correlation in corneal staining between the eyes indicates that the two eyes of a subject cannot serve as independent data points. One-third of the subjects who participated in this study had notable corneal staining. This finding underlines the importance of regularly checking corneal staining in clinical practice.

Contact Lenses↗

PubMed1996

Standardized rigid contact lens fitting protocol for keratoconus.

Keratoconus is typically managed by a variety of rigid contact lens fitting techniques and lens designs. The two most fundamental fitting techniques are apical corneal touch (including divided or three-point touch) and apical clearance. In the course of designing a multi-center study of keratoconus patients, a standardized keratoconus fitting protocol was developed. All contact lens parameter options are uniform except for base curve and secondary curve radii, which are determined by interpretation of fluorescein patterns using the CLEK Study trial lens set and protocol. The initial trial lens's base curve is the average keratometric reading; sequentially steeper lenses are applied until definite apical clearance is observed. We have evaluated the feasibility of this standardized fitting protocol on 30 keratoconus patients. Our results suggest that we have developed a standardized contact lens fitting set and fitting protocol to simplify contact lens management in patients with mild to moderate keratoconus.

Contact Lenses↗

PubMed1996

Feasibility of fitting contact lenses with apical clearance in keratoconus.

Despite the wide variety of rigid contact lens fitting philosophies for the visual correction of keratoconus, questions remain, including which approach-flat, divided support, or steep-contributes the most toward the preservation of a clear cornea. One goal of the Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Pilot Study was to determine the feasibility of managing early keratoconus patients with apical clearance rigid contact lenses. Of 30 keratoconus patients identified with at least 1 nonscarred cornea, 17 patients (30 eyes) were randomly assigned to a steep lens fitting protocol. After trial fitting with a standardized lens design demonstrating minimum apical clearance, lenses were dispensed whose base curve was 0.2 mm steeper than the minimum apical clearance lens. Patients were re-evaluated on a quarterly schedule concluding at 12 months. Changes in keratometry between baseline and 12 months identified unequal steepening of the flat and steep corneal curvatures, suggestive of corneal molding. Best corrected rigid lens visual acuity measures illustrated no significant changes over the course of the study. Clinically significant corneal compromise was transiently observed in some patients. Only 1 of 22 eyes completing the pilot study and fitted with apical clearance developed mild corneal scarring.

Adolescent↗

PubMed1996

The relationship between corneal eccentricity and improvement in visual acuity with orthokeratology.

BACKGROUND: Due to the renewed attention given to reduction of myopia, interest in orthokeratology has dramatically increased. This study was performed to determine whether or not a predictor for orthokeratologic changes can be identified. METHODS: Fifteen subjects enrolled in the study. For each subject, corneal eccentricity (e) was measured, subjective refraction and autorefraction were performed, and intraocular pressures were taken. Each subject was then fitted with a rigid contact lens for orthokeratology and followed for a minimum of 16 weeks. Eleven subjects completed the study. RESULTS: No correlation between corneal eccentricity and improvement in visual acuity was found. Correlations were found between e and changes in subjective refraction, and between e and changes in autorefraction. There was also correlation between lower intraocular pressure and changes in subjective refraction, and between lower intraocular pressure and changes in autorefraction. CONCLUSIONS: These findings suggest that corneal eccentricity and lower intraocular pressures may be predictors of orthokeratologic changes. A longitudinal study with a larger subject size will be needed to conclusively determine if these two measurements are predictors of orthokeratologic changes.

Contact Lenses↗

PubMed1995

Keratoconus.

Keratoconus is characterized by the presence of corneal distortion (secondary to thinning of the apex) and either Fleischer's ring (found in 57% of patients) or Vogt's striae (found in 44% of patients). Often the only presenting symptom is decreased visual acuity. Steep keratometric readings are not usually diagnostic; 18% of patients with keratoconus have readings flatter than 45.00 D. Treatment requires correction of acuity with spectacles or contact lenses. More advanced cases are generally managed with rigid gas-permeable contact lenses. Corneal scarring occurs in approximately 43% of cases; 10% to 20% of patients require penetrating keratoplasty to restore acuity.

Contact Lenses↗

PubMed1994

A comparative study of techniques for decreasing contact lens storage case contamination.

BACKGROUND: Contact lens storage cases may harbor a variety of pathogenic organisms, and are a potential source of ocular infection. In this study, we evaluated the anti-microbial efficacy of several methods of rinsing of contact lens storage cases. METHODS: Lens cases were inoculated with Pseudomonas aeruginosa and then 1) rinsed with hot tap water and closed without drying, 2) rinsed with hot tap water followed by air drying, 3) rinsed with 3% hydrogen peroxide followed by air drying, or 4) left closed and undisturbed (control condition). After 24 hours, the cases were cultured to determine the rate of disinfection. RESULTS: The hydrogen peroxide rinse was the most effective (99.5 percent of cases disinfected), followed by hot water with air drying (94.7 percent) and hot water without drying (51.1 percent). Significant residual hydrogen peroxide was detected in the cases rinsed with peroxide. CONCLUSIONS: Therefore, we recommend that patients be instructed to rinse their cases with hot water and allow them to air dry after use, as well as replace their cases on a regular basis.

Colony Count, Microbial↗

PubMed1989

Soft contact lens and corneal changes associated with Visine use.

Sixteen subjects were fit with Cibasoft clear daily wear contact lenses and were asked to use two drops of tetrahydrozoline (Visine) twice a day for 4 months on one eye. Visual acuity, lens coloration, and slit lamp results were compared to baseline data between the test and control eye of each subject. Visual acuity and lens coloration results showed statistically insignificant changes from baseline. However, clinically important changes in corneal integrity were noted in 26.7% of the subjects.

Administration, Topical↗

PubMedDate not supplied

Photodocumentation of corneal scarring. Collaborative Longitudinal Evaluation of Keratoconus Study Group.

PURPOSE: A standardized system for photodocumenting corneal scars and for evaluating these photographs does not exist and is essential for clinical research. To address this need, we developed a system for photographing and evaluating corneal scars. METHODS: In the "Development Phase," we tested several procedures in small samples totaling 40 eyes of 20 keratoconus patients. In the "Test Phase," we used an independent sample of 150 eyes of 82 keratoconus patients. Fifty-nine of these 150 eyes had corneal scars, and 91 of the eyes did not as determined by the clinician. RESULTS: The photography protocol requires four central parallelepiped and two whole cornea oblique photographs after pupil dilation. With the clinician as gold standard, this technique yielded sensitivity of 96% and specificity of 83%. Evaluation of the corneal photographs as to the presence or absence of corneal scarring was performed independently by two masked readers. Agreement between clinicians on the presence of corneal scarring was 0.99 (kappa); agreement between readers for the presence of scarring was 0.80 (kappa). CONCLUSIONS: The corneal photography protocol we describe is recommended for use in clinical investigations of cicatricizing corneal disease and appears robust enough to be used in multicenter studies.

Corneal Diseases↗