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Abstract
Purpose
The present study evaluated the changes in tear film, cornea and ocular surface according to the duration of soft contact lens wear.
Methods
A total 65 patients with 130 eyes were enrolled the present study, and were divided into 4 grous. The control group (group A) was composed of 32 eyes of 16 patients who had not worn soft contact lenses, group B, (34 eyes of 17 patients), had worn soft contact lenses less than 5 years, group C, (32 eyes of 16 patients), had worn soft contact lenses for 5 to 10 years and group D, (32 eyes of 16 patients), had worn soft contact lenses for more than 10 years. The tear break-up time (BUT), Schirmer's test, corneal sensitivity test, central corneal thickness, ocular surface disease index (OSDI), corneal fluorescein staining score, specular microscopy and conjunctival impression cytology were analyzed. The results were compared between the control group and the soft contact lens groups.
Results
In group B, BUT significantly decreased, but corneal fluorescein staining score and squamous metaplasia significantly increased (p < 0.05). In group C, OSDI and snake-like chromatin pattern significantly increased, but corneal thickness and goblet cell density significantly decreased (p < 0.05). In group D, the coefficient of variation for endothelium significantly increased, but corneal sensitivity and hexagonality significantly decreased (p < 0.05).
Figures and Tables
Figure 1
Impression cytologic finding of squamous metaplasia (PAS-H&E, ×400) (A) Specimen from a patient of normal subject (Group A) shows round epithelial cells with a nucleocytoplasmic ratio of 1:2 (squamous metaplasia grade 0). (B) Soft contact lens wearers within 5 years (Group B). Epithelial cells show similar shape with Group A, but cell size slightly increases and nucleocytoplasmic ratio decreases (squamous metaplasia grade 1). (C) Soft contact lens wearers for 5 to 10 years (Group C). Epithelial cells with a nucleocytoplasmic ratio of 1:4 are visible (squamous metaplasia grade 2). (D) Soft contact lens wearers more than 10 years (Group D). The large, polygonal epithelial cells with a nucleocytoplasmic ratio of 1:10 are visible (squamous metaplasia grade 3).
Figure 2
Impression cytologic finding of goblet cell density (PAS-H&E, ×100). (A) Specimen from a patient of normal subject (Group A) shows a large amount of goblet cell density. (B) Soft contact lens wearers within 5 years (Group B). Group B shows a slightly decreased goblet cell density. (C) Soft contact lens wearers for 5 to 10 years (Group C). Group C shows a severe decreased goblet cell density. (D) Soft contact lens wearers more than 10 years (Group D). No goblet cells can be seen.
Figure 3
Impression cytologic finding of snake-like chromatin (PAS-H&E, ×400). Snake like chromatin, sticklike structure that is axially arranged in the center of an elongated nucleus, is shown significantly in the soft contact lens wearers for more than 5 years.
Table 2
The changes of tear film, cornea and ocular surface according to the duration of soft contact lens wear
Values are presented as mean ± SD.
*Non-contact lens wearers; †Soft contact lens wearers who had used it for less than 5 years; ‡Soft contact lens wearers who had used it for 5-10 years; §Soft contact lens wearers who had used it for more than 10 years; ∥Statistically significant compared to the Group A (ANOVA test, p<.05); #Statistically significant compared to the Group A (Mann-Whitney test and Kruskal-Wallis test, p<0.05).
Table 3
Mean endothelial cell density, coefficient of variation and hexagonality measured by specular microscopy in each groups
Values are presented as mean ± SD.
*Non-contact lens wearers; †Soft contact lens wearers who had used it for less than 5 years; ‡Soft contact lens wearers who had used it for 5-10 years; §Soft contact lens wearers who had used it for more than 10 years; ∥Statistically significant compared to the Group A (ANOVA test, p<0.05).
Table 4
The results of conjunctival impression cytology according to the groups
Values are presented as mean ± SD.
*Non-contact lens wearers; †Soft contact lens wearers who had used it for less than 5 years; ‡Soft contact lens wearers who had used it for 5-10 years; §Soft contact lens wearers who had used it for more than 10 years; ∥Statistically significant compared to the Group A (Mann-Whitney test and Kruskal-Wallis test, p<0.05); #Statistically significant compared to the Group A (ANOVA test, p<0.05); **Statistically significant compared to the Group A (Fisher's exact test, p<0.05).
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