Short-Term Intraocular Pressure Rise during Locally Induced Force by Ophthalmologic Surgery Applications

Abstract

Purpose: Surgical or diagnostic procedures are often accompanied by a short-term increase in intraocular pressure (IOP). A short-term increase in IOP can occur during refractive procedures, vitreoretinal surgery, transillumination, photocoagulation, or cryocoagulation. A porcine eye model was chosen (n = 89) to compile comparable study data and to de termine correlations between the force induced and the resulting intraocular pressure while excluding the effect of surgeons. Methods: The IOP was measured in the anterior chamber. IOP changes were induced by applying an external force and measured when using a cannula, trocar, and cryocoagulation (n = 32), and correlations between force and resulting IOP were assessed (n = 57). Results: A correlation was noted between the force induced and the IOP increase, which showed a linear dependency. The insertion of a 29-G cannula caused a mean ΔIOP value of 49.1 ± 2.9 mm Hg and an external force of 0.76 N, and that of a 23-G trocar 344.4 ± 5.9 mm Hg and 6.09 N, respectively. The rise in IOP during a simulated cryocoagulation reached values between 57.3 ± 14.8 mm Hg (cryoprobe tip diameter: 0.9 mm) and 130.3 ± 2.9 mm Hg (cryoprobe tip diameter: 7.0 mm). Conclusion: The values of the forces applied can be converted into the resulting IOP based on the specific action. Surgical or diagnostic procedures should, therefore, be evaluated with regard to preexisting pathologies, such as glaucoma.

Determination of Correlated Color Temperature in Ex Vivo Porcine Eyes during Intraocular Illumination

“…The CCT was determined for 3 different pressures in the anterior chamber, namely 23, 78, and 132 mmHg, in a total of 105 eyes for the halogen lamp and 18 eyes for the xenon lamp. By applying a force on the eyewall, the intraocular pressure in the anterior chamber increases, according to the correlation reported in [30]. To generate a consistent force on the eyewall, the intraocular pressure was measured because each eye was slightly different in its anatomy.…”