Abstract
Abstract: :
Purpose: In the OHT Treatment Study, thinner corneas were linked to increased risk of developing OAG. We investigated lamina cribrosa displacement and changes in ONH blood flow following IOP reduction, and correlated them with corneal thickness Methods: 16 OHT and 16 OAG patients underwent Heidelberg Retina Tomography (HRT) and Scanning Laser Doppler Flowmetry (SLDF, analyzed with SLDF software v 3.3) before and at least two months following a mean 35% sustained therapeutic IOP reduction. Each group was split into two ("Thin" and "Thick") based on median CCT determined by ultrasound pachymetry. Results: In the group composed of the Thin OHT and Thin OAG patients (n=16, mean CCT 518 +/–32 µm) compared to the group composed of the Thick OHT and Thick OAG patients (n=16, mean CCT 587 +/–31 µm) greater reductions were seen in mean cup depth (34 +/– 32 µm vs. 4 +/– 36 µm, p=0.018) and cup volume (47 +/– 75µm3 vs. 7 +/– 34µm3 , p=0.06). The same pattern was present in both OHT and OAG patients, and virtually all parameters showed larger changes in the Thin groups. Smaller improvements in neuroretinal rim blood flow were seen in both OAG and OHT patients with thinner corneas compared to those with thicker corneas, but this difference only reached significance in the OAG group (55 +/– 66 a.u. vs. 190 +/– 80 a.u., p=0.0017). Conclusions: OAG and OHT patients with thinner corneas show significantly greater lamina cribrosa displacement (compliance) and smaller improvements of neuroretinal rim blood flow following IOP reduction. These findings suggest that the link between ONH compliance, ONH blood flow changes and glaucomatous progression requires further investigation.
Keywords: blood supply • optic disc • cornea: clinical science