Idiopathic spontaneous filtering bleb: Is there an autoimmune etiology?

Abstract

A 45-year-old male presented with complaints of defective vision for near. There was no prior history of trauma, recurrent redness, or surgery. He is a known patient of hypothyroidism and vitiligo. His best-corrected visual acuity was 6/6, N6 in both the eyes (BE). Slit-lamp examination revealed a diffuse, elevated, avascular thin bleb near the limbus in the superonasal quadrant with underlying scleral thinning in BE. Right eye (RE) showed clear cornea, quiet and deep anterior chamber, normal iris pattern, and clear lens. Left eye (LE) showed peripheral corneal vascularisation with lipid deposits at 10'o clock anterior to the area of scleral thinning and bleb formation, the rest of the anterior segment was normal [Fig. 1a and b]. Schirmer's test was normal and Seidel's test did not reveal any leak in BE. His intraocular pressure was 9 and 10 mm Hg in the RE and LE, respectively. Gonioscopy revealed open angles in BE with an area of hyperpigmentation around fistula at 2 o'clock in the RE and increased pigmentation with prominent iris processes in the nasal quadrant in LE [Fig. 1c and d]. The fundus examination revealed an average size disc with a cup to disc ratio of 0.4:1, healthy neuroretinal rim and attached retina in BE.Figure 1: Right eye showing superonasal diffuse avascular thin bleb (a). Left eye showing superonasal diffuse avascular thin bleb with scleral thinning, corneal vascularisation, and lipid deposits (b). Gonioscopy showing fistula with hyperpigmentation anterior to schwalbe's line at 2'0 clock (arrowhead) in the right eye (c) and increased pigmentation with prominent iris processes in the nasal quadrant in left eye (d). Ultrasound biomicroscopy image of the right (e) and left (f) eye showing communicating fistula between the anterior chamber and subconjunctival space, indicated by the arrowheadsCorneal topography was suggestive of oblique astigmatism with flattening along the meridian of the bleb without evidence of corneal ectasia in BE. Ultrasound biomicroscopy revealed a communicating fistula between the anterior chamber and subconjunctival space in BE [Fig. 1e and f]. Physical examination was unremarkable, except for depigmented patches in the skin. Blood investigations revealed high thyroid peroxidase antibody titer (157 IU/mL), whereas C-reactive protein, rheumatoid factor, and antinuclear antibody were within normal limits. Discussion Spontaneous filtering bleb is a rare condition, which can develop if a communicating fistula between the anterior chamber and subconjunctival space is established. Spontaneous filtering bleb has been reported in patients with Axenfeld syndrome,[1] Terrien marginal degeneration,[2] Traboulsi syndrome,[34] connective tissue diseases,[56] and without any ocular or systemic association.[27] Our patient with hypothyroidism and vitiligo, has scleral thinning and subconjunctival bleb in both the eyes. There were no signs of anterior segment abnormalities or facial dysmorphism. Considering the fact that our patient has 2 autoimmune systemic conditions, we postulate that the scleral thinning and spontaneous bleb formation could be due to autoimmune etiology. 2.1 Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. 2.2 Financial support and sponsorship Nil. 2.3 Conflicts of interest There are no conflicts of interest.