Abstract
Purpose: :
To reveal clinical features of tear film findings associated with filtration blebs created by trabeculectomy with the use of three-dimensional anterior segment optical coherence tomography (3D AS-OCT).
Methods: :
The included in this study were 151 eyes that underwent trabeculectomy. By using 3D AS-OCT, tear film sings associated with filtration blebs were identified. By using custom software, lengths, heights, circumferences and areas were calculated for the identified tear film. The elucidated quantitative data were analyzed in association with clinical background and bleb morphology. The obtained data of the tear film associated with filtration blebs were compared with 3D AS-OCT images of lower tear meniscus in normal healthy volunteers. Also, by using enucleated porcine eyes in which silicone tires (or viscoelastic materials) were implanted subconjunctivally, tear film was also analyzed by using 3D AS-OCT, and the examined eyes were subsequently subjected to histopathological investigation in order to elucidate the association between OCT images and histology.
Results: :
Tear film sign associated with filtration bleb was found in 45 (30%) of the 151 eyes. The tear film sign was found on or along bumpy blebs in all of the 45 yes. In contrast, in eyes with flat and dome-shaped blebs, no tear film signs were noted. The mean thickness (± standard deviation, SD) of the tear film surface signal was 42.3 ± 3.1 μm (range, 33 to 48 μm), which was very similar to that or lower tear meniscus, 41.4 + 1.2 μm (range, 39 to 43 μm) (P = 0.40). The mean intraocular pressures (± SD) were 11.2 + 4.9 mmHg and 15.3 ± 6.0 mmHg in the eyes with and without tear film sign, respectively (P <0.001). Also, the mean values (± SD) of length, area and circumference of tear film sign were 769.8 ± 451.3 μm (range, 283 to 2235 μm), 57.7 ± 57.0 x 103 μm2 (range, 16 to 357 x 103μm2) and 1,634.6 ± 871.4 μm (range, 632 to 4702 μm), respectively. The same values for lower tear meniscus were 351.5 ± 107.3 μm (range, 231 to 500 μm), 39.0 ± 22.1 x 103μm2 (18 to 71 x 103μm2) and 1092.1 ± 395.3 μm (range, 698 to 1715 μm), respectively. Our animal models for bumpy bleb morphology demonstrated the presence of tear film signs on or along the bleb in wet status treated with instillation of artificial tear fluid, but not in dry status. Also, conjunctival flap design (limbal- and fornix- based) influenced on tear film signals in those experimental eyes.
Conclusions: :
Our results showed that the bleb morphology caused the occurrence of tear film signs on or along the blebs and that the shape and length of the tear film is dependent on bleb morphology, which is different from case to case.
Keywords: imaging/image analysis: clinical