Alterations in the morphology of lamina cribrosa pores in glaucomatous eyes

Aims: To determine alterations which occur in the size and shape of lamina cribrosa (LC) pores in glaucomatous eyes over a period of time. Methods: Baseline and follow up optic disc photographs were retrospectively studied in 39 eyes of 39 patients with glaucoma. Only eyes with a vertical cup to disc ratio equal to or greater than 0.6 were included in the study. In addition, all selected eyes had to have serial optic disc photographs obtained at least 3 years apart allowing clear visualisation of LC surface. The association of the alterations in LC surface morphology with patient specific and eye specific characteristics was statistically analysed. Results: During a mean study period of 3.90 (SD 0.7) years, individual pore size (mean pore area to disc area ratio) exhibited a significant decrease between baseline and follow up measurements of each eye (p<0.0001). However, during the study period, total pore area to disc area ratio did not change (p>0.05), and the change in pore shape in some eyes (from circular to more oval and elongated) was statistically insignificant (p = 0.12). Although a relation was detectable between the optic disc and lamina cribrosa parameters at a given time, which reflects cumulative effects, during the study period, there was no significant association between the changes of the LC parameters and neural tissue damage. The rate and the magnitude of the changes in individual pore size during the study period were not significantly different among the eyes exhibiting progressive neural rim damage and those staying stable (p>0.05). Conclusion: These findings demonstrate that the LC surface morphology exhibits changes along with the glaucomatous optic disc damage. However, the clinical appearance of LC surface in glaucomatous eyes may continue to change, even when the neural rim damage is clinically stable. These findings are probably associated with the chronic cellular events of tissue remodelling that occur in the glaucomatous optic nerve head.