Seidel and India ink tests assessment of different clear cornea side-port incision configurations

Post-cataract endophthalmitis has increased after introduction of clear cornea incisions (CCI). Laboratory models suggested that these incisions might not be competent at certain changes in intraocular pressure (IOP). Considering that side-port incisions (SPI) might behave similarly, the purpose of the present study was to determine the most stable side-port incision configuration.

Using four cadaveric human eyes, four different side-port incisions (SPI) were created in each cornea: 1.5 mm and 2.5 mm squared tunnel, 1.5 mm and 2.5 mm stab tunnel. Fluorescein was placed on the eye, and the IOP varied from 10 to 80 mmHg. IOP at which each SPI started leaking was recorded. In the second part of the study, India ink was applied to the corneal surface at normal IOP, and then rinsed with balanced salt solution (BSS). The ink influx was recorded by planimetry. IOP was elevated to 80 mmHg, ink was reapplied, and IOP was dropped to 0 mmHg. Ink influx was measured again. Histological examination was used to visualize ink inflow into each incision.

There was no statistically significant difference in the IOP levels at which the different incisions leaked (p = 0.52). A significant increase in the length of India ink ingress in all incision types was measured after IOP variation (p < 0.05). The 2.5 mm squared incision showed the least increase in ink inflow in this test.

All incision types of SPIs tested exhibited similar resistance to leakage after IOP variation. Good resistance to wound leakage may not predict adequate resistance to the inflow of bacterial-sized particles into the wound.