Purpose: To evaluate the effect of preoperative intraocular pressure (IOP) and the vacuum level on IOP during femtosecond laser-assisted cataract surgery. Methods: Intraocular pressure was measured in 40 enucleated porcine eyes by intracameral manometry prior, during and after vacuum application using the VICTUS femtosecond laser platform (Bausch&Lomb, Technolas Perfect Vision GmbH, Germany). Twenty combinations of different preoperative IOP levels (12, 16, 20 and 24 mmHg) and different vacuum levels (350-550 mbar) were investigated. Results: Multivariate regression analysis indicated that both the vacuum level (beta = 0.138; p < 0.001) but much stronger the preoperative IOP (beta = 0.861; p < 0.001) were predictive factors for IOP rise during vacuum application. Mean IOP was 28.23 AE 3.86, 34.23 AE 3.92, 40.35 AE 4.41 and 46.82 AE 4.11 mmHg in groups with baseline IOP of 12, 16, 20 and 24 mmHg, respectively. In the 350, 450 and 550 mbar group, and mean IOP was 35.85 AE 7.85, 37.33 AE 7.90 and 39.00 AE 8.04 mmHg, respectively. Lowering the preoperative IOP by 2 mmHg and reducing the vacuum from maximum to minimum resulted in a similar reduction in IOP during vacuum application (À3.10 AE 0.79 mmHg versus À3.15 AE 0.88 mmHg; p = 0.015). Furthermore, decreasing the baseline IOP from 20 to 12 mmHg resulted in a 30.0% reduction in intraoperative IOP. Conclusion: Preoperative IOP was a stronger predictive factor for intraoperative IOP rise than the applied vacuum level. Measurements and critical interpretation of preoperative IOP in a preliminary examination could help estimating the individual risk of significant IOP rise during femtosecond laser-assisted cataract surgery and could help taking early countermeasures in selected cases. Due to the porcine ex vivo model, further studies are needed to verify these findings.
Background
Clinical outcome after successful reorientation of an upside-down implanted DMEK (Descemet Membrane Endothelial Keratoplasty) graft 4 weeks after initial transplantation.
Case presentation
A 71-year-old woman presented with Fuchs’ endothelial corneal dystrophy for DMEK. After initial DMEK the donor graft was fully attached and well centred during intracameral gas filling. When the gas bubble was fully resorbed the graft started to detach. Therefore, two intracameral gas injections were consecutively performed. During the second re-bubbling, an upside-down orientation was observed and so the graft was flipped, centred, re-attached and finally stabilized by an intracameral gas bubble. Three weeks after reorientation slit lamp examinations showed a well centred and attached graft, endothelial cells that started functioning and a patient’s visual acuity of 20/40. Visual acuity increased to a 20/32 vision in the observed eye three months later and further improved to 20/20 6 months after reorientation and stayed stable between 20/32 and 20/20 during the remaining 15 months of follow-up, with a clear and well-attached graft.
Conclusion
Reorientation of an upside down DMEK graft was successful even 4 weeks after initial DMEK. Visual recovery and endothelial cell count increase were stepwise noticed during the first 6 months and 15 months after reorientation, respectively. Finally a favourable outcome with 20/32 to 20/20 vision at least 6 months after graft reorientation was achieved. Therefore, restoring full graft function could last several weeks or even months following (late) reorientation of an upside-down DMEK graft.
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