Dumbleton K A, Chalmers R L, Richter D B, Fonn D
Centre for Contact Lens Research, School of Optometry, University of Waterloo, Ontario, Canada.
Optom Vis Sci. 2001 Mar;78(3):147-51. doi: 10.1097/00006324-200103000-00006.
The purpose of this study was to determine the impact of extended wear of high and low oxygen permeability (Dk) lenses on the development or resolution of limbal hyperemia and corneal neovascularization in a randomized prospective clinical trial.
Adapted daily-wear contact lens wearers were randomly assigned to one of two groups. The low-Dk group (N = 23) wore etafilcon A lenses (Dk/t = 40) for up to 7 days and 6 nights, and the high-Dk group (N = 39) wore lotrafilcon A lenses (Dk/t = 175) for up to 30 days and nights. Limbal hyperemia and neovascularization were assessed and graded during 9 months of extended wear. A stratified analysis to determine how change in ocular redness depended on initial presentation was also conducted.
On a 0 to 100 scale, extended wear of low-Dk lenses resulted in a 16-point increase in limbal hyperemia (p < 0.0001); no significant change occurred with the high-Dk lenses. The difference was greatest for low-Dk participants who initially presented with lower levels of hyperemia (N = 18). There was a slight resolution of redness in participants who initially presented with higher levels of hyperemia (N = 10) after wearing the high-Dk lenses. Neovascularization increased by an average of 0.5 on a scale of 0 to 4 in low-Dk lens wearers (p < 0.0001) but remained unchanged in the high-Dk lens wearers. The increase was most marked for the low-Dk group with lower levels of neovascularization at baseline.
Subjects who wore lenses with higher oxygen permeability for 9 months of extended wear exhibited a lower vascular response of the ocular surface compared with subjects who wore lenses of lower oxygen permeability for the same period. This result was found both for the surface limbal vessels and in the deeper neovascular stromal vessels. Moderate neovascularization also developed after 3 months of extended wear of low-Dk hydrogels, whereas high-Dk lenses caused no neovascularization.
本研究旨在通过一项随机前瞻性临床试验，确定高透氧性（Dk）和低透氧性镜片的长时间佩戴对角膜缘充血的发展或消退以及角膜新生血管形成的影响。
将习惯每日佩戴隐形眼镜的佩戴者随机分为两组。低Dk组（N = 23）佩戴依他氟康A镜片（Dk/t = 40）长达7天6夜，高Dk组（N = 39）佩戴lotrafilcon A镜片（Dk/t = 175）长达30天30夜。在长达9个月的长时间佩戴期间评估并分级角膜缘充血和新生血管形成情况。还进行了分层分析，以确定眼部发红的变化如何取决于初始表现。
在0至100的评分标准下，低Dk镜片的长时间佩戴导致角膜缘充血增加16分（p < 0.0001）；高Dk镜片则未出现显著变化。对于初始角膜缘充血水平较低的低Dk参与者（N = 18），这种差异最为明显。在佩戴高Dk镜片后，初始角膜缘充血水平较高的参与者（N = 10）的发红情况略有消退。低Dk镜片佩戴者的新生血管形成在0至4的评分标准下平均增加了0.5（p < 0.0001），而高Dk镜片佩戴者则保持不变。对于基线新生血管形成水平较低的低Dk组，这种增加最为显著。
与同期佩戴低透氧性镜片的受试者相比，佩戴高透氧性镜片长达9个月的受试者眼部表面的血管反应较低。这一结果在角膜缘表面血管和更深层的新生血管基质血管中均有发现。低Dk水凝胶镜片长时间佩戴3个月后也出现了中度新生血管形成，而高Dk镜片未导致新生血管形成。
