Abstract
Abstract: :
Purpose: Scanning laser ophthalmoscopy (SLO Rodenstock Instr. Germany) allows imaging of the lamina cribrosa using HeNe laser illumination (588 nm). The ultrastructural changes of the pores were examined in patients with glaucoma and in healthy controls. Methods: Images of the anterior portion of the lamina cribrosa were captured when focussing through the optic nerve head excavation and digitally processed. The visible pores were delineated interactively evaluating area and elongation of the pores. The measurements were correlated with visual function and optic nerve head morphology (Heidelberg Retina Tomography; HRT). In this study, 16 healthy subjects with physiological optic nerve head excavation were compared to 16 patients with either normal tension or primary open angle glaucoma. Results: The area (glaucoma: 4147± 7889 µm2; control: 3040 ±367 µm2; p=0.0003) and the elongation (glaucoma: 1.81 ±0.36; control: 1.50 ±0.27; p=0.001) of the lamina cribrosa pores were significantly increased in patients with glaucoma. Both measurements were significantly correlated to each other (r=0.58; p=0.0004). The area of the pores increased with decreasing visual acuity (logMAR; r=0.39, p=0.02) but was not related to visual field indices. Compared to HRT measurements the area of pores correlated significantly with the cup to disk area (r=0,5; p=0.04) and cup shape measurement (r=0.6; p=0.01), whereas the elongation correlated with the maximum excavation depth (r=-0.5; p=0.04). Conclusions: The non-invasive imaging of the lamina cribrosa allows in vivo assessment of pore area and geometry. The area and elongation of pores are significantly increased in glaucoma patients and correlated with optic nerve head morphology. Future studies should aim if there are alterations in early manifest glaucoma and if differences among different types of glaucoma can be observed.
Keywords: imaging/image analysis: clinical • lamina cribrosa • image processing