Representative photographs, phase retardation and intensity images with PS-OCT and intensity images with 3D cornea and anterior segment OCT (3D CAS-OCT) are shown in
Figure 1. A case of PS-OCT phase retardation Grade 1 blebs is shown in
Figure 1A. A 72-year-old female patient had a good bleb in her left eye. Seven years after trabeculectomy, the IOP was 7 mm Hg without glaucoma medication (
Fig. 1A). In a PS-OCT phase retardation Grade 1 bleb, the vast green region above the sclera and no abnormal birefringence was found in the phase retardation image, whereas the sclera showed strong phase retardation. Diffusely thickened blebs with a large hyporeflective area and multiple microcysts were observed in the intensity images with PS-OCT and 3D CAS-OCT. Two cases of a PS-OCT phase retardation Grade 3 bleb are shown in
Figures 1B and
1C. Case 1: A 66-year-old male patient had a flat bleb in his right eye, then two years after trabeculectomy, the IOP was 16 mm Hg with full glaucoma medication (
Fig. 1B). Case 2: Four years after trabeculectomy, a 56-year-old male with a collapsed flat bleb (
Fig. 1B) had an IOP of 21 mm Hg with full glaucoma medication (
Fig. 1C). In this bleb, a fluid pool was almost invisible. The whole region of the conjunctiva presented with irregular and abnormal phase retardation as shown by the corresponding phase retardation images. No hyporeflective area and microcysts were observed in the intensity images with PS-OCT and 3D CAS-OCT (
Fig. 1B). In case 2, a highly elevated localized bleb and a large fluid pool surrounded by hyperreflective tissue were observed (
Fig. 1C). Despite a highly elevated appearance, it was not possible to determine the normality of this tissue property from OCT intensity images. In contrast, the corresponding phase retardation image presented strong-phase retardation that was encircling the fluid pool (
Fig. 1C). According to the general anatomy of the eye, conjunctival structures do not possess phase retardation properties.
19,20 In healthy subjects, there is no abnormal phase retardation in conjunctiva (
Supplementary Fig. S1). Hence, this appearance in
Figures 1B and
1C indicates abnormal phase retardation.