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.

Characteristics of Tear Lipid Layer Patterns on Tearscopy and Lipid Layer Thickness

This study is to evaluate thickness of lipid layer, NIBUT (non-invasive tear film break-up time), BUT and Schirmer value according to tearscopic pattern of lipid layer.The subjects are seventy-one eyes from seventy-one people without ocular diseases.The pattern of lipid layer is observed by Tearscope(r) (Keeler, U.K.)and the thickness of lipid layer is measured by interference generated from slit lamp microscope.The thickness of lipid layer, NIBUT and BUT are respectively measured three times and averaged.In the case of the pattern of lipid layer, eighteen eyes have the close meshwork type, twenty-nine eyes have the wave type, fifteen eyes have the amorphous type and nine eyes have the color fringe type.The average value of the thickness of lipid layer, NIBUT, BUT and Schirmer test were respectively 29.3 nm, 25.9 seconds, 12.0 seconds, 18.6 mm for close meshwork;47.2 nm, 33.6 seconds, 12.5 seconds, 16.9 mm for wave;66.2 nm, 39.7 seconds, 14.9 seconds, 18.7 mm for amorphous;and 74.4 nm, 30.9 seconds, 13.9 seconds, 18.9 mm for color fringe.The thickness of lipid layer was different significantly among the patterns.NIBUT showed significant difference between close meshwork and wave, and between close meshwork and amorphous.The Cronbach alpha, reproducibility of the test, is 0.84 in the thickness of lipid layer, 0.64 in NIBUT, 0.76 in BUT and 0.94 in Schirmer test.The reproducibility of the pattern of lipid layer observed by Tearscope(r) is 95.8%.

The Change of Ocular Surface after Cataract Surgery

The authors evaluated whether cataract surgery developed ocular surface changes or not. Fifty three cataract patients were divided into 2 groups according to the method of subconjunctival injection at the end of the operation. In the first group, betamethason was injected in the lower nasal quadrant and gentamicin was injected in the lower temporal quadrant. In the second group, both betamethason and gentamicin were injected together in the lower nasal quadrant. The tear film break-up time and Schirmer test results were reduced significantly after cataract surgery in both groups. Goblet cell numbers were reduced significantly on the 12 o'clock, lower temporal quadrant and lower nasal quadrant conjunctiva, and especially that of the lower quadrant, in which gentamicin was injected, was reduced more. Instilled drug before and after the operation, electric cauterization, conjunctival incision, and subconjunctival injection of drugs, such as gentamicin and betamethason, may induce the precorneal tear film instability.