Intraocular Pressure Reconstitution and Maintenance for Cadaveric Porcine Eyes in Simulated Wet-Lab Experience
Narrative Responses:
Purpose
To determine a cost-effective way in maintaining adequate intraocular pressure in practice eyes (cadaveric porcine) in the anterior segment intraocular surgery wet-lab. To compare intraocular pressure and corneal clarity on eyes which have been reconstituted with economical and easily prepared compounds (gelatin and isotonic normal saline).
Methods
Prospective randomized data collection in 25 porcine eyes. Primary outcome was intraocular pressure (IOP) by tonopen and 2º outcome was corneal clarity. Thirty pig eyes were obtained, 25 were usable. Anterior chambers were reformed using a plain gelatin solution (10 eyes), isotonic normal saline (10 eyes), or ophthalmic viscosurgical devices (OVD, 5 eyes). A corneal wound was constructed with a slit knife. IOP and corneal clarity were graded at 0, 24, and 48 hrs. Corneal opacity was graded on a scale of 0-4 with grade 0 being clear to grade 4 being opaque with no view of the pupil.
Results
Kruskal-Wallis analysis, p-value <0.05 statistically significant. In the gelatin eyes, at 0 hrs mean IOP was 25.4 mmHg (SD 5.2), and was maintained at 24 hrs (20.2, SD 6.2) and 48 hrs (20.9, SD 9.4). In the normal saline (NS) eyes, at 0 hrs mean IOP was 20.5, SD 8.0, and at 24 and 48 hrs IOP was unmeasurable. At 0 hrs, there was no significant IOP difference between gelatin and NS (p>0.05), but at 24 and 48 hours there was, p<0.05 (p=0.000053). There was no significant corneal opacity difference at measured intervals including 48 hrs, p=0.865 (NS and gelatin).
Conclusion
Gelatin is an economical compound which maintains IOP well over time better than normal saline. Gelatin and isotonic normal saline can be easily prepared in the wet-lab and are a fraction of the cost compared to commercial OVDs. The viscosity and optical clarity of gelatin is subjectively similar to OVDs.