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Editors Selection IGR 9-2

Anatomical Structures: Lamina cribrosa displacement II

Comment by Sung-Chul Park on:

54422 Variation of lamina cribrosa depth following trabeculectomy, Lee EJ; Kim TW; Weinreb RN, Investigative Ophthalmology and Visual Science, 2013; 54: 5392-5399

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Lee et al. investigated the long-term changes in the lamina cribrosa (LC) position following trabeculectomy. Anterior LC displacement ('reversal of posterior LC displacement') was observed in all eyes during initial follow-up (surgery to postoperative six months) with an overall decrease in mean IOP (27.4 to 9.7 mmHg), and a variable degree of posterior LC displacement ('redisplacement') was noted in nine of 28 eyes during subsequent follow-up (postoperative six months to ≥ two years) with an overall increase in mean IOP (9.7 to 12.7 mmHg). This redisplacement of the LC during subsequent follow-up was associated with younger age, higher mean IOP and IOP fluctuation during follow-up, and higher final IOP. These findings confirm the in-vivo long-term IOP-induced changes in the LC position and the age-related differences in the LC compliance.

In 25 of 28 eyes, the posterior LC displacement has been reversed during the entire follow-up (surgery to postoperative ≥ two years). This suggests decrease in the stress and strain within the LC connective tissue, possibly leading to improvement of the retinal ganglion cell axon homeostasis and stabilization of glaucoma, which often occurs after successful trabeculectomy. As the authors mentioned, detailed three-way relationships among LC position change, IOP change and visual field change warrant further investigation in larger-scale and longer-term studies.

Interestingly, among the three IOP variables (mean follow-up IOP, IOP fluctuation during follow-up, and final IOP), the IOP fluctuation had the strongest association with the degree of LC redisplacement (posterior LC displacement) during subsequent follow-up (postoperative six months to ≥ two years). For example, in one eye, the LC was displaced posteriorly by approximately 200 µm during this period, although the mean follow-up IOP and final IOP were in the low-teens. In this eye, IOP fluctuation was approximately 9 mmHg, which was the highest among 28 eyes. This suggests that repeated exposure to high IOP (e.g., monthly intra-vitreal anti-VEGF injections) may put substantial stress to the retinal ganglion cells, potentially leading to glaucoma progression.

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