Pullum K W, Stapleton F J
Optometry Department, Moorfields Eye Hospital, London, England.
CLAO J. 1997 Oct;23(4):259-63.
Scleral lenses remain an option for visual rehabilitation under some circumstances or when there are specific therapeutic indications. Wearing is often limited with polymethylmethacrylate lenses, but rigid gas permeable (RGP) scleral lenses offer a physiological improvement as measured with central corneal swelling. This study aimed to determine central corneal swelling with lenses of different oxygen transmissibilities and thicknesses.
Central corneal swelling was measured in four normal subjects wearing sealed RGP scleral contact lenses for 3 hours. The lenses used were of Dk 32, 59, and 115 with thicknesses of 0.15, 0.30, 0.60, and 1.20 mm. A reduction in central corneal swelling was associated with an increase in Dk and a reduction in lens thickness (P < 0.05). This relationship was found to be non-linear for higher transmissibilities.
The physiological improvement as measured by central corneal swelling was reduced with thin high Dk lenses, suggesting diminishing returns for further increases in Dk. For usual scleral lens thicknesses of 0.6 mm in a material with a Dk of 115, the mean central corneal swelling induced was less than 3%.
在某些情况下或存在特定治疗指征时，巩膜镜仍是视觉康复的一种选择。聚甲基丙烯酸甲酯镜片的佩戴通常受到限制，但硬性透气性（RGP）巩膜镜可使中央角膜肿胀程度得到生理性改善。本研究旨在确定不同透氧性和厚度的镜片对中央角膜肿胀的影响。
对4名正常受试者佩戴密封的RGP巩膜接触镜3小时后的中央角膜肿胀情况进行测量。所使用的镜片的Dk值分别为32、59和115，厚度分别为0.15、0.30、0.60和1.20毫米。中央角膜肿胀程度的降低与Dk值的增加及镜片厚度的减小相关（P < 0.05）。对于较高的透氧性，发现这种关系是非线性的。
高Dk值的薄镜片使通过中央角膜肿胀测量的生理性改善降低，这表明进一步增加Dk值的收益递减。对于Dk值为115的材料，通常巩膜镜厚度为0.6毫米时，诱导的平均中央角膜肿胀小于3%。
