Gürdal Canan, Aydin Sevda, Kirimlioğlu Hale, Toprak Ebru, Sengör Tomris
Department of Ophthalmology, PTT Education and Research Hospital, Istanbul, Turkey.
Ophthalmologica. 2003 Sep-Oct;217(5):329-36. doi: 10.1159/000071347.
New contact lens materials with high oxygen permeability are said to be convenient for the extended-wear (EW) schedule. We evaluated the short-term effect of EW soft contact lens usage on ocular surface and central corneal thickness.
Fifty-two eyes of 26 patients were included in the study. Sixteen of the patients used the high oxygen-permeable lenses for a 30-day extended-wear schedule (group I). Ten patients used the lenses on a daily wear basis (DW, group II). All patients were evaluated for visual acuity and central corneal thickness by corneal and conjunctival biomicroscopy, Schirmer and tear break-up time (BUT) tests. Impression cytology was performed in the superior/temporal, inferior/nasal quadrants of the conjunctiva, 1 mm from the limbus, with cellulose acetate filter paper. The specimens were graded under light microscopy according to Nelson's classification.
Three patients in the EW group were excluded from the study as they discontinued lens usage due to slight discomfort and hyperemia. Biomicroscopic findings and tear function tests indicated no increased pathological results. Central corneal thickness decreased from 554 +/- 9.55 to 546 +/- 9.30 microm (mean +/- SEM) in the EW group (p = 0.002), whereas no significant change occurred in the DW group. Cytological evaluation of the EW group showed an 88% increase in metaplasia (p = 0.007), especially close to the limbal areas and in the superior quadrants; this ratio was 30% in the DW group. Snake-like chromatin changes were found to be increased, from 4 to 6 patients, in the EW group while it remained the same in the DW group (p > 0.05). Individual comparisons of the initial and final pathological conditions of the ocular surfaces in the two groups showed that there was an increase in pathology in the EW group while there was no significant difference in the DW group.
On a 30-day extended-wear basis with high oxygen-permeable lenses, the possible development and increase of conjunctival cytologic changes secondary to mechanical trauma is one of the main remaining problems. Conjunctival and related immunologic pathologies should not be overlooked when prescribing an extended-wear lens schedule.
据说具有高透氧性的新型隐形眼镜材料便于长期佩戴（EW）方案。我们评估了长期佩戴软性隐形眼镜对眼表和中央角膜厚度的短期影响。
26例患者的52只眼纳入研究。其中16例患者采用高透氧镜片进行为期30天的长期佩戴方案（I组）。10例患者每日佩戴镜片（DW，II组）。通过角膜和结膜生物显微镜检查、泪液分泌试验和泪膜破裂时间（BUT）测试对所有患者的视力和中央角膜厚度进行评估。使用醋酸纤维素滤纸在距角膜缘1mm的结膜上/颞侧、下/鼻侧象限进行印迹细胞学检查。标本在光学显微镜下根据纳尔逊分类法进行分级。
EW组有3例患者因轻微不适和充血而停止使用镜片，被排除在研究之外。生物显微镜检查结果和泪液功能测试表明，未出现病理性结果增加。EW组中央角膜厚度从554±9.55微米降至546±9.30微米（平均值±标准误）（p = 0.002），而DW组未发生显著变化。EW组的细胞学评估显示化生增加88%（p = 0.007），尤其是在靠近角膜缘区域和上象限；DW组这一比例为30%。EW组发现蛇形染色质变化的患者从4例增加到6例，而DW组保持不变（p>0.05）。两组眼表初始和最终病理状况的个体比较显示，EW组病理状况有所增加，而DW组无显著差异。
在使用高透氧镜片进行30天长期佩戴的情况下，机械性创伤继发结膜细胞学变化的可能发展和增加是主要遗留问题之一。在开具长期佩戴镜片方案时，不应忽视结膜及相关免疫病理学问题。
