McMahon T T, Polse K A
UIC Eye Center, Eye and Ear Infirmary, Chicago, IL 60612.
J Am Optom Assoc. 1994 Nov;65(11):788-90.
Recent studies have shown that some long-term PMMA contact lens wearers who are presumably exposed to hypoxia can develop modest but permanent changes in corneal structure and function. What is not known is the corneal effects that may result from severe and long-term exposure to an hypoxic environment. This case report is presented to illustrate an extreme example of the effects of the cornea from prolonged exposure to hypoxia.
A 37-year-old male who had worn PMMA lenses on a 2-week extended wear basis for 20 years was examined in the laboratory to assess changes in corneal structure and function. Function was determined by monitoring the rate at which the cornea recovered from induced edema and is expressed as a percent recovery per hour (PRPH). Morphology was studied via specular microscopy.
For this subject, the PRPH was 39.6 percent/hr and 40.5 percent/hr for right and left eyes respectively; these values are substantially reduced compared to the reported 55.3 percent/hr for an age-matched, non-contact lens wearing population. Specular microscopy demonstrated reduced cell counts of 1,052 cells/mm2 OD and 1,741 cells/mm2 OS compared to an age adjusted normal population with 2,853 +/- 320 cells/mm2.
This case example appears to represent an extreme case of contact lens abuse and the effects of long-term hypoxic contact lens wear on corneal function.
近期研究表明，一些长期佩戴聚甲基丙烯酸甲酯（PMMA）隐形眼镜且可能处于缺氧状态的人，角膜结构和功能会出现轻微但永久性的变化。然而，长期严重暴露于缺氧环境对角膜产生的影响尚不清楚。本病例报告旨在说明长期暴露于缺氧环境对角膜影响的一个极端例子。
对一名37岁男性进行检查，该男性佩戴PMMA隐形眼镜，每2周连续佩戴20年，在实验室评估其角膜结构和功能的变化。通过监测角膜从诱发水肿中恢复的速率来确定功能，以每小时恢复百分比（PRPH）表示。通过镜面显微镜研究形态学。
该受试者右眼和左眼的PRPH分别为39.6%/小时和40.5%/小时；与年龄匹配的非隐形眼镜佩戴人群报告的55.3%/小时相比，这些值大幅降低。镜面显微镜显示，与年龄调整后的正常人群（2853±320个细胞/mm²）相比，右眼细胞计数为1052个细胞/mm²，左眼为1741个细胞/mm²。
本病例似乎代表了隐形眼镜滥用以及长期缺氧佩戴隐形眼镜对角膜功能影响的一个极端案例。
