Application of optical coherence tomography in orthokeratology fitting / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To assess the gap between the peak of the base curve to the surface of the cornea, as well as examines the correlation between the thickness of the tear film and the fitting of the orthokeratology lens through optical coherence tomography(OCT), providing an intuitive and quantitative clinical evaluation method for the fitting of the orthokeratology lens.METHODS: Myopia patients who fitted orthokeratology at our hospital from January to December 2023 were included. Examinations, including naked vision, slit lamp, non-contact intraocular pressure, ocular fundus, eye position, corneal diameter, corneal topography, tear film rupture time, optometry, etc., were performed on all patients before fitting. The trial lens parameter was selected according to the examination results, and fluorescein staining was performed to evaluate lens fitting state after patients adapted to wearing glasses. According to the performance of fluorescein staining, the inspected eyes are divided into three groups: lens loose group, lens fitting group, and lens tight group. In addition, the tear film thickness of three groups of subjects was measured by OCT, and the differences between the three groups of data were evaluated.RESULTS: A total of 49 myopic patients(77 eyes)were included. The average sphere degree was -3.10±1.25 D, the average cylinder degree was -0.43(-0.75, 0)D, the average horizontal keratometry(HK)was 42.48±0.81 D, and vertical keratometry(VK)was 42.98(42.25, 43.50)D. There were 21 cases(34 eyes)in the lens fitting group, with 13 cases of bilateral eyes, 8 cases of one eye, 14 cases(22 eyes)in the lens loose group, with 8 cases of bilateral eyes, 6 cases of one eye, and 14 cases(21 eyes)in the lens tight group, with 7 cases of bilateral eyes, 7 cases of one eye. There was no statistical difference in the main basic data of the subjects in the three groups(all P>0.05). OCT showed that the tear film thickness of the lens fitting group, the lens loose group, and the lens tight group was 231.18(219.0, 243.0), 220.41(214.0, 224.3), and 249.00(241.5, 258.0)μm, respectively, and there was statistical significance in the thickness among the three groups(P<0.05).CONCLUSION: OCT can serve as a safe and reliable method for measuring the tear film thickness, which can help evaluate the suitability of orthokeratology and provide a non-invasive, more intuitive, and quantitative evaluation method for the fitting and evaluation of orthokeratology.

Observation of tear film thickness and corneal parameters in moderate and good night wearing of orthokeratology / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To measure the tear film thickness when with a good fitted night wear orthokeratology lens in youth, and observe the change of corneal parameters. <p>METHODS: From July 2015 to August 2016, 51 eyes of 26 teenagers with myopia who would wear orthokeratology and accept regular follow-up were enrolled. The mean spherical equivalent refraction of teenagers was -2.78D±1.53D(-1.00D to-6.00D)before wearing orthokeratology, and the mean astigmatism was 1.29D±0.61D(0 to -2.68D). The tear film thickness were measured by optical coherence tomography(OCT)when the eyes wearing orthokeratology for 1mo. The surface regularity index(SRI)value was measured by corneal topography to compare its relationship with the tear film thickness and the changes of corneal anterior surface parameters during the period of wearing lens were observed. <p>RESULTS: At 1mo after wearing orthokeratology, the mean tear film thickness of right eyes was 230.09±10.40μm, and that was 224.38±10.57μm of left eyes. The mean tear film thickness was 228.75±9.66μm in male eyes and that was 224.80±6.74μm in female eyes. The mean tear film thickness of all eyes was 227.05±10.29μm, and the mean SRI value was 0.16±0.14. There was no correlation between tear film thickness and SRI value(<i>P</i>>0.05). The FK value, SK value and average K value from before wearing to after wearing for 2d and 1wk gradually decreased, the difference was statistically significant(<i>P</i><0.05). There was no statistical difference among wearing for 1wk, 1, 3 and 6mo(<i>P</i>>0.05). <p>CONCLUSION: OCT can be used as a safe and reliable method for measuring the thickness of the tear film space during the wearing of orthokeratology, which may be of certain value for the safety assessment of the long term wearing of orthokeratology. Orthokeratology works very quickly, corneal curvature decreases rapidly 2d after wearing and stabilizes during the period.

Measurement of Precorneal Tear Film Using Scheimpflug Camera and Relationship with Parameters for Dry Eye

PURPOSE: To compare the anterior segment parameters including precorneal tear film thickness (PTFT) using Pentacam(R) (Oculus, Wetzlar, Germany) between normal control and dry eye groups and to examine the relationships between the PTFT and other parameters for dry eye. METHODS: The present study included 23 normal controls (31 eyes) and 25 patients with dry eyes (31 eyes). We compared measurements including PTFT, corneal thickness and astigmatism using Pentacam(R) and analyzed the correlations among the PTFT and fluorescein tear break-up time (FBUT), Schirmer I test (without anesthesia), and ocular surface disease index (OSDI). RESULTS: The mean PTFT in dry eyes (21.1 +/- 2.0 microm) was significantly thinner than in normal eyes (37.6 +/- 2.0 microm; p < 0.01). In the dry eye group, the corneal thickness was thicker than in the normal eye group but there were no clinically significant differences. The dry eye group experienced more frequent and severe corneal astigmatism compared with the normal group. OSDI scores showed a weak negative correlation with objective clinical measures of dry eye (FBUT, Schirmer I test) but was not statistically significant. However, OSDI was statistically significantly negatively correlated with PTFT (r = -0.46, p < 0.01). The PTFT showed a weak positive correlation with FBUT and Schirmer I test without statistical significance. CONCLUSIONS: The mean PTFT using Pentacam(R) in the dry eye group was thinner than in the normal group. Additionally, the PTFT was correlated with subjective symptoms. Therefore, the PTFT measurement using Pentacam(R) could be considered a useful method for diagnosis and treatment of dry eye.

The Comparison of Viscosity-dependent Distribution of Tear Film after Dropping of Three Artificial Tears

We intended to evaluate the viscosity-dependent distribution of tear film after dropping of three artificial tears with different viscosity. We measured the corneal thickness including tear film thickness after dropping of Optagent[Povidon iodide 2%; viscosity: 1.5millimeter2/sec], Tears naturale free[hydroxypropyl methylcellulose 0.3%, dextran 0.1%;6.4 millimeter2/sec], Lacura [sodium hyaluronate 0.1%;4.6 millimeter2/sec]in 12 adult men and women without dry eye by optical beam scanning differential pachymetry of Orbscan topography. 1 minute after dropping, the thickness of 3 millimeter superior and inferior to center of cornea increased respectively 4.1 +/-0.4 micrometer, 0.4 +/-0.1micrometer[p=0.014]in Optagent, 2.4 +/-0.3 micrometer, 2.3 +/-0.2 micrometer[p=0.425]in Tears naturale free and 2.5 +/-0.5 micrometer, 2.0 +/-0.2 micrometer[p=0.126]in Lacure. 10 minute after dropping, the thickness of 3 millimeter superior and inferior to center of cornea increased respectively 2.7 +/-0.3 micrometer, 0.3 +/-0.1 micrometer[p=0.025]in Optagent, 1.7 +/-0.2 micrometer, 1.6 +/-0.2 micrometer[p=0.326]in Tears naturale free and 1.4 +/-0 .4 micrometer, 1.2 +/-0.2 micrometer[p=0.237]in Lacura. In conclusion, the artificial tears with relatively high viscosity dstributed evenly along the corneal surface after dropping, but those with relatively low viscosity distributed mainly superior to center of cornea with statistical significance. So when treating of corneal lesion in dry eye, we think that artificial tears with proper viscosity will be needed according to the location of the lesion.

The Comparison of Viscosity-dependent Distribution of Tear Film after Dropping of Three Artificial Tears

We intended to evaluate the viscosity-dependent distribution of tear film after dropping of three artificial tears with different viscosity. We measured the corneal thickness including tear film thickness after dropping of Optagent[Povidon iodide 2%; viscosity: 1.5millimeter2/sec], Tears naturale free[hydroxypropyl methylcellulose 0.3%, dextran 0.1%;6.4 millimeter2/sec], Lacura [sodium hyaluronate 0.1%;4.6 millimeter2/sec]in 12 adult men and women without dry eye by optical beam scanning differential pachymetry of Orbscan topography. 1 minute after dropping, the thickness of 3 millimeter superior and inferior to center of cornea increased respectively 4.1 +/-0.4 micrometer, 0.4 +/-0.1micrometer[p=0.014]in Optagent, 2.4 +/-0.3 micrometer, 2.3 +/-0.2 micrometer[p=0.425]in Tears naturale free and 2.5 +/-0.5 micrometer, 2.0 +/-0.2 micrometer[p=0.126]in Lacure. 10 minute after dropping, the thickness of 3 millimeter superior and inferior to center of cornea increased respectively 2.7 +/-0.3 micrometer, 0.3 +/-0.1 micrometer[p=0.025]in Optagent, 1.7 +/-0.2 micrometer, 1.6 +/-0.2 micrometer[p=0.326]in Tears naturale free and 1.4 +/-0 .4 micrometer, 1.2 +/-0.2 micrometer[p=0.237]in Lacura. In conclusion, the artificial tears with relatively high viscosity dstributed evenly along the corneal surface after dropping, but those with relatively low viscosity distributed mainly superior to center of cornea with statistical significance. So when treating of corneal lesion in dry eye, we think that artificial tears with proper viscosity will be needed according to the location of the lesion.