Wang Jianhua, Fonn Desmond, Simpson Trefford L, Jones Lyndon
Centre for Contact Lens Research, School of Optometry, University of Waterloo, Waterloo, Ontario, Canada.
Invest Ophthalmol Vis Sci. 2003 Jun;44(6):2524-8. doi: 10.1167/iovs.02-0731.
To demonstrate the feasibility of indirectly measuring the precorneal tear film thickness and pre- and postlens tear film (PLTF) thickness using optical coherence tomography (OCT).
Central corneal thickness (C(1)) which includes the tear film (T) of both eyes of 40 non-contact lens wearers was measured using OCT after calibration. The mean age of the 40 subjects was 31.2 +/- 9.3 years with a mean horizontal K-reading of 7.87 mm. Rigid contact lenses with base curves 0.3- to 0.5-mm steeper than the flattest K of the eye were fitted to measure real corneal thickness (C(2)), independently of the postlens tear film. T was calculated by T = C(1) - C(2). To measure pre- and postlens tear film thickness, Focus Night & Day and Acuvue lenses (Vistakon, Johnson & Johnson Vision Care, Jacksonville, FL) were fitted on both eyes. Central soft lens thickness (L(1)), which includes the prelens tear film (P), was measured by OCT in situ and in saline in a wet cell (L(2)). P was calculated by P = L(1) - L(2). Thickness of the central cornea plus the postlens tear film (C(3)) was measured during lens wearing. Postlens tear film (PLTF) was calculated by PLTF = C(3) - C(2). RESULTS. The mean +/- SD precorneal tear film thickness was 3.3 +/- 1.5 microm (range, 0-6.9) before lens insertion and 4.7 +/- 2.3 microm (range, 0.7-11.0) after lens fitting, which was significantly thicker (paired t-test: P < 0.01). The prelens tear film thickness was 3.9 +/- 2.6 and 3.6 +/- 2.1 microm (mean +/- SD; paired t-test: P = 0.52) and the postlens tear film thickness was 4.5 +/- 2.3 and 4.7 +/- 3.1 microm (paired t-test: P = 0.08) on and under Focus Night & Day and Acuvue lenses, respectively. Post hoc tests showed that precorneal (baseline) and prelens tear films were equivalent, and each was different (thinner; Tukey honestly significant difference P < 0.05) from the postlens tear film.
OCT can noninvasively measure the thickness of the precorneal and prelens tear film as well as the postlens tear film. The thickness of the normal precorneal tear film is approximately 3 micro m and becomes thicker after lens fitting. The postlens tear film is thicker than the precorneal and prelens tear films with soft contact lenses. The thickness of both pre- and postlens tear films appears to be independent of the investigated lens types.
证明使用光学相干断层扫描（OCT）间接测量角膜前泪膜厚度以及晶状体前后泪膜（PLTF）厚度的可行性。
对40名非隐形眼镜佩戴者的双眼进行校准后，使用OCT测量包括泪膜（T）的中央角膜厚度（C(1)）。40名受试者的平均年龄为31.2±9.3岁，平均水平角膜曲率读数为7.87 mm。佩戴比眼睛最平角膜曲率陡0.3 - 0.5 mm基弧的硬性隐形眼镜，以测量真实角膜厚度（C(2)），独立于晶状体后泪膜。通过T = C(1) - C(2)计算T。为测量晶状体前后泪膜厚度，在双眼佩戴Focus Night & Day和Acuvue镜片（Vistakon，强生视力健公司，佛罗里达州杰克逊维尔）。通过OCT原位测量以及在湿盒盐水中测量包括晶状体前泪膜（P）的中央软性镜片厚度（L(1)）（L(2)）。通过P = L(1) - L(2)计算P。在佩戴镜片期间测量中央角膜加晶状体后泪膜（C(3)）的厚度。通过PLTF = C(3) - C(2)计算晶状体后泪膜（PLTF）。结果：镜片插入前角膜前泪膜平均厚度±标准差为3.3±1.5μm（范围0 - 6.9），配镜后为4.7±2.3μm（范围0.7 - 11.0），明显更厚（配对t检验：P < 0.01）。Focus Night & Day和Acuvue镜片上和下的晶状体前泪膜厚度分别为3.9±2.6和3.6±2.1μm（平均±标准差；配对t检验：P = 0.52），晶状体后泪膜厚度分别为4.5±2.3和4.7±3.1μm（配对t检验：P = 0.08）。事后检验表明角膜前（基线）和晶状体前泪膜相等，且两者均与晶状体后泪膜不同（更薄；Tukey真实显著性差异P < 0.05）。
OCT可以无创测量角膜前和晶状体前泪膜以及晶状体后泪膜的厚度。正常角膜前泪膜厚度约为3μm，配镜后变厚。软性隐形眼镜的晶状体后泪膜比角膜前和晶状体前泪膜厚。晶状体前后泪膜厚度似乎与所研究的镜片类型无关。
