The effects of experimental tear film removal on corneal surface regularity and barrier function.
Ophthalmology
; 107(9): 1754-60, 2000 Sep.
Article
em En
| MEDLINE
| ID: mdl-10964840
ABSTRACT
PURPOSE:
To evaluate corneal surface regularity and asymmetry, corneal thickness, barrier function, and contrast sensitivity after experimental removal of the precorneal tear layer.DESIGN:
Prospective, clinic-based, nonrandomized (self-controlled) comparative trial.PARTICIPANTS:
Six eyes of six healthy volunteers (three males, three females; age range, 29-40 years).METHODS:
A precorneal tear lesion was created by pressing a sterile Biopore (Millipore, Bedford, MA) Teflon membrane against the central cornea. Corneal topography with both the Topographic Modeling System (TMS-1; Computed Anatomy, Tomey Technology, Cambridge, MA) and the Orbscan (Orbscan Inc., Salt Lake City, UT) were performed before the lesion was created and 30 seconds, 1 hour, and 4 hours after the lesion was created. Surface regularity and surface asymmetry indices were evaluated by the TMS-1 topography system. Maximum and minimum keratometric readings, corneal fluorescein staining, contrast sensitivity, and corneal thickness were evaluated before and after the tear lesion. Cytologic membranes were stained for MUC4 mucin using an indirect immunofluorescent staining technique. Confocal microscopy was performed to evaluate the integrity of the corneal epithelium in two eyes. Analysis of variance with polynomial contrasts was used to examine time trends of the outcome variables. MAIN OUTCOMEMEASURES:
The change in corneal surface regularity and asymmetry indices, corneal thickness, permeability to fluorescein dye, and contrast sensitivity before and after the lesion was made were compared.RESULTS:
The corneal epithelium in the area of the lesion showed intense fluorescein staining 30 seconds postlesion but appeared normal by 4 hours. Confluent, homogeneous staining for MUC4 mucin was observed on the membranes used to create the lesion in all cases. The surface regularity index measured with the TMS-1 increased after the lesion was created and decreased toward normal by 4 hours (P = 0.017). Corneal thickness measured by the Orbscan instrument significantly increased in the central (P = 0.001), superior (P = 0.006), inferotemporal (P < 0.001) and superotemporal (P = 0.001) cornea immediately following the lesion and returned to normal by 4 hours. The lesion caused a decrease in visual acuity at 6.30%, 4% and 2.5% contrast sensitivities 1 hour postlesion and these measurements returned to prelesion values by 4 hours (P = 0.085, P = 0.005, P = 0.043).CONCLUSIONS:
The precorneal tear layer serves as a permeability barrier and is essential for maintaining a smooth quality optical surface.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Lágrimas
/
Sensibilidades de Contraste
/
Córnea
Tipo de estudo:
Observational_studies
/
Prognostic_studies
Limite:
Adult
/
Female
/
Humans
/
Male
Idioma:
En
Revista:
Ophthalmology
Ano de publicação:
2000
Tipo de documento:
Article
País de afiliação:
Estados Unidos
País de publicação:
EEUU
/
ESTADOS UNIDOS
/
ESTADOS UNIDOS DA AMERICA
/
EUA
/
UNITED STATES
/
UNITED STATES OF AMERICA
/
US
/
USA