Ultrastructure alteration in the corneal stroma of hydrated camel corneoscleral button and corneal button

To investigate the changes in the ultrastructural architecture of hydrated corneoscleral button (HCSB) and hydrated corneal button (HCB).

Corneoscleral buttons (n = 4) and corneal buttons (n = 4) were hydrated in deionized water for 24 and 48 h and were fixed in 2.5% glutaraldehyde containing cuprolinic blue in sodium acetate buffer and processed for electron microscopy. The tissue was dehydrated and embedded in TAAB 031 resin. Normal CSB and CB were also processed using the same method. Ultrathin sections were stained with uranyl acetate and lead citrate. The sections were observed under JEOL 1400 transmission electron microscope.

In both HCSB and HCB, the lamellae were disorganized and proteoglycans (PGs) were degenerated and detached from the collagen fibrils (CFs). In the HCSB samples, interfibrillar spacing increased but the diameter of the CF had not changed compared with those in the normal tissue. Within the HCSB, the interfibrillar spacing in the posterior stroma was significantly higher compared with those in the anterior and middle stroma. In the HCB, both the interfibrillar spacing and CF diameter had significantly increased compared to those observed in both the HCSB and normal tissue. The CFs were severely damaged exhibiting very thin microfilaments within CFs. Remnants of the CFs were present in the stromal matrix.

Hydration of the cornea in both the HCSB and HCB increases the interfibrillar spacing in the anterior, middle, and posterior stroma. The CF in the HCB was enlarged and had degenerated. This could be due to penetration of water into the intermolecular spacing within the CF.