Evaluation of active and inactive pterygium with en face anterior segment optical coherence tomography and correlations with in vivo confocal microscopy and MMP-9 dosage.

Abstract

Purpose: To compare en face anterior segment optical coherence tomography (OCT) characteristics in active and inactive pterygium and to correlate the findings with in vivo confocal microscopy (IVCM) images and MMP-9 dosage.

Methods: In this observational case series, we prospectively included 9 eyes of 8 subjects with active pterygium (AP) and 10 eyes of 8 subjects with inactive pterygium (IP). Patients with recurrent pterygium were excluded. After a written informed consent, all subjects underwent detailed ophthalmic examination, anterior segment photography, an evaluation of ocular surface disease index (OSDI), IVCM, and en face anterior segment spectral OCT. En face OCT images were analyzed for the surface of Fuchs patchs in front of the tip of the pterygium. Post operatively, the MMP-9 gene expression in pterygium biopsy was assessed. The correlations between en face OCT images, IVCM activity and MMP-9 dosage were then analyzed and compared in both groups.

Results: En face OCT allowed clear visualization and evaluating the surface of Fuchs patchs in front of the tip of pterygium. The surface of Fuchs patches was larger in AP than in IP (0.16 +/- 0.06 mm2 versus 0.08 +/- 0.04 mm2 respectively) (p = 0.001). There was a good correlation between the surface of Fuchs patchs and IVCM analysis and MMP-9 expression. A larger surface of Fuchs patchs was associated with higher score of activity on IVCM and higher expression of MMP-9.

Conclusions: As previously reported, the presence of Fuchs patches is associated with pterygium activity, their visibility is associated to the presence of dendritic cells, which possibly participate in the activation of proliferation. En-face anterior segment SD-OCT allowed the evaluation of the surface of these patches and showed that AP were associated with a largest Fuchs patchs. There was a good correlation between en face OCT findings and those of OSDI, IVCM and MMP-9 dosage. By providing a simple, non invasive and reproducible method to analyze pterygium activity, en face OCT could be a promising way to evaluate the pterygium activity before surgery.