SEP 04, 2012
This prospective study found that the reversal of optic disc cupping after glaucoma treatment is mostly likely the result of anterior movement of the lamina cibrosa (LC), in addition to other factors, such as decompression of the LC and restoration of prelaminar tissue.
The authors used spectral domain OCT to investigate changes in the lamina cibrosa and prelaminar tissue in 35 primary open-angle glaucoma patients who underwent trabeculectomy. The pre- and postoperative magnitude of LC displacement (distance from Bruch's membrane opening plane to the level of anterior LC surface) and the thickness of LC and prelaminar tissue were determined on seven to 13 selected B-scan images in each eye.
At six months postop, the significant decrease in IOP (from 27.2 mmHg to 10.5 mmHg) was accompanied by a significant reduction in posterior displacement of the LC and a significant increase in the thickness of the LC and prelaminar tissue.
The magnitude of the reduction in LC displacement was significantly associated with younger age (P < 0.001), greater percentage IOP reduction (P = 0.019) and greater preoperative LC displacement (P = 0.024). None of the factors was associated with the amount of LC or prelaminar tissue thickening.
The majority of the reduction in posterior cup displacement occurred during the early postoperative period, with additional gradual decreases observed after week one. Does this suggest that perhaps surgery, which achieves an almost instant lowering of IOP, may be a better choice of therapy in glaucoma? A study comparing the changes in the LC between groups of patients treated initially with medicine or surgery might answer this question. Finally, although all of the patients in the study had baseline visual fields, no mention was made of the effect of this reversal of cupping on the outcome of follow-up fields.
The authors write that the importance and influence of the LC reversal on disease prognosis remains to be determined. However, based on current understanding of the role of LC displacement in the pathogenesis of glaucomatous damage, it may be proposed that LC reversal could be a sign of released strain at the level of the LC that may provide relief to the compressed nerve fibers or laminar capillaries.