Expansion of the human microphthalmic orbit

OBJECTIVE

To determine the effects of long-term, incremental enlargement of an orbital tissue expander on bone and eyelid growth in microphthalmia.

DESIGN

A prospective, noncomparative case series.

PARTICIPANTS

Five consecutive patients with microphthalmos treated with orbital expansion were evaluated.

INTERVENTION

A tissue expander was placed into the orbits of five children (age, 10 months-6 years) with unilateral microphthalmos and gradually enlarged by saline injections.

MAIN OUTCOME MEASURE

The midorbital width of each patient was determined from axial computed tomographic scans before insertion of the device. The length of the normal and abnormal eyelid fissures was measured at surgery. The postexpansion dimensions of both the normal and microphthalmic orbits and the eyelids were remeasured when the expanders were removed. The residual deficits between the normal and the microphthalmic sides were expressed in percentages.

RESULTS

Gradual inflation of the expander to a diameter of 22 mm reduced the average preoperative orbital dimension deficit of the group from 14.6% (range, 8%-25%) to 3.8% after surgery (range, 0.5%-6.3%). The average pre-expansion eyelid length deficit for the group was 17.5% (range, 12%-26%) compared to 2.3% (range, 0.0%-5.3%) after expansion. The average expansion period was 56.8 weeks (range, 20-100 weeks). Two outpatient surgical procedures were required in each patient.

CONCLUSION

Incremental inflation of a tissue expander placed within the microphthalmic orbit induced sufficient osseous and eyelid growth to ameliorate the major stigmata of this syndrome in all patients treated.

Long-term evaluation of corneal endothelial cell transplantation

PURPOSE

This report describes the clinical course, refractive changes, confocal microscopic and histological evaluation of corneal endothelial cell transplantation in rabbits with long-term follow-up.

METHODS

Transplantation of corneal endothelial cells using a cell/carrier device was performed in 19 rabbits. Clinical evaluation between 1-25 months included slit-lamp examination, keratometry, retinoscopy and surface topography. Two grafts in rabbits with 12 and 24 month survivals were evaluated in vivo by 3D tandem scanning confocal microscopy. The same grafts were then processed for transmission electron microscopy. BrdU labeling of the grafted cells in one transplant was performed in order to distinguish between host and grafted endothelial cells.

RESULTS

All grafts cleared and remained clear for an average of one year without signs of rejection or inflammation. Postoperative refraction data and topography of the transplants showed progressive development of myopia and steep corneas compared to the unoperated eyes in each case. Confocal microscopy in vivo demonstrated a regular hexagonal pattern of the transplanted endothelial cells and a thickened Descemet's membrane, which correlated with the light and electron microscopic findings. BrdU labeling of the grafted endothelial cells showed a homogenous labeling of cell nuclei 6 months after the transplantation.

CONCLUSIONS

This study demonstrates that corneal endothelial cells grown on a biomaterial can be replaced and remain functional for a long period of time.

Corneal endothelial wound repair in normal and mitotically inhibited cultures

BACKGROUND

The aim of the present study was to compare the morphology, proliferative activity and cytoskeletal organization of bovine corneal endothelial cells during wound healing under normal and mitotically inhibited conditions.

METHODS

Cell cultures were grown to confluency and incubated with the mitotic inhibitor 5-fluorouracil (5-FU; 2.5 micrograms/ml) followed by a touch wound. Control cultures were maintained without 5-FU. Mitotic activity, F-actin, vinculin, vimentin and connexin 43 localization were evaluated before, during and after wound closure.

RESULTS

5-FU inhibited irreversibly the mitotic activity of corneal endothelial cells during the whole wound healing process. In the presence of 5-FU, a high degree of polymegathism and delay in actin and vinculin redistribution to the cell borders after wound closure was observed. Vimentin and connexin 43 immunolabeling revealed only slight differences between 5-FU-treated and control cultures.

CONCLUSIONS

Significant changes in cell geometry and cytoskeletal organization in the amitotic corneal endothelium became manifested only after wounding. These changes may influence cell-cell and cell-matrix interactions as well as functional restoration of the monolayer after wound closure.

Transplantation of corneal endothelial cells using a cell carrier device

Penetrating keratoplasty is currently the only treatment for corneal endothelial dysfunction. Although corneal transplantation has a high success rate, a few problems still remain, such as the limited availability of donor grafts, the change in refraction after penetrating keratoplasty, and the higher chance of immune rejection. In this study, a coated hydrogel lens (Chiron Ophthalmics Inc., Irvine CA, U.S.A.) has been used as a carrier to transplant cultured homologous kitten and rabbit corneal endothelial cells into adult cats and rabbits. The transplantation procedure was the same in both species. Corneal endothelial cells from homologous rabbits or cats were seeded on coated hydrogel lenses and cultured until they reached a complete monolayer with an average cell density of 2,500 cells/mm2. Five weeks before transplantation surgery, corneal endothelial cells were scraped to induce corneal edema. The cell carrier device was then transplanted as follows: a trephine cut (7.7 mm) was made into the stroma, producing an outer corneal plug. The inner cornea was then cut by using a 5.5-mm trephine, and this inner plug was discarded. The implant was inserted and the outer corneal plug was sutured back into place. Corneas cleared completely within 3 days in both rabbits and cats, and stayed clear for an average of 40 days in rabbits and 50 days in cats. The histopathological evaluation of the rejected grafts showed vascularized retrocorneal membrane formation in cats, whereas in rabbits severe cellular infiltration of the stroma with neovascularization occurred without retrocorneal membrane formation.

Plume emission, shock wave and surface wave formation during excimer laser ablation of the cornea

Excimer lasers are now used for corneal surgery; however, the physical processes occurring during photoablation of the cornea are incompletely understood. High speed laser-based photographic arrangement was constructed. The temporal resolution was better than 1 ns. The setup could work as a Schlieren arrangement, which is sensitive to the refractive index change caused by the shock wave propagating in the air above the eye. With minor changes the setup was converted into a shadowgraph, which could detect the ablation plume and the waves propagating on the surface of the eye. Due to the impact of the excimer laser pulse onto the surface of the cornea, a shock wave was generated in the air. The shadowgraph clearly showed the ejection of the ablated cornea. The ejection velocity of the plume was found to be over 600 m/s. It was shown for the first time that the recoil forces of the plume are generating a wave on the surface of the eye. The laser-based high speed photographic arrangement is a powerful arrangement in the study of physical effects occurring during photoablation of the cornea.

Vancomycin in corneal transplantation

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