Real-time intraocular pressure measurement during phacoemulsification in dogs ex vivo

Gonioscopic iridocorneal angle morphology and incidence of postoperative ocular hypertension and glaucoma in dogs following cataract surgery

PURPOSE

To investigate the relationship between gonioscopic iridocorneal angle (ICA) morphology and the incidence of postoperative ocular hypertension (POH) and postoperative glaucoma in dogs undergoing cataract surgery.

ANIMALS STUDIED

Retrospective analysis of 138 eyes of 78 canine patients who underwent phacoemulsification at North Carolina State University from December 1, 2015 through April 30, 2017.

METHODS

Medical records of all phacoemulsification patients with preoperative RetCam gonioscopic images were reviewed for preoperative, intraoperative, and postoperative variables. Gonioscopic angle indices were calculated using a novel (ZibWest) angle grading system, and these indices were analyzed for outcome-related significance.

RESULTS

Increased surgeon experience was associated with increased probability of POH and vision loss. Higher average ZibWest Angle indices (ie, more open angles with less pectinate ligament dysplasia/ abnormality) were associated with a significantly decreased probability of medically unresponsive glaucoma. Increased patient age was significantly associated with an increased probability of both postoperative glaucoma and vision loss. Female dogs were significantly more likely to experience postoperative glaucoma compared to male dogs. Increased surgery time was significantly associated with increased probability of vision loss.

CONCLUSIONS

The ZibWest angle index may predict increased risk for developing medically unresponsive glaucoma with cataract surgery. Female sex, and increased patient age, surgical time, and surgeon experience were associated with increased postoperative morbidity.

Influence of an intentionally induced posterior lens capsule rupture on the real-time intraocular pressure during phacoemulsification in canine ex vivo eyes

OBJECTIVE

To evaluate the changes in the intraocular pressure (IOP) following an intentionally induced posterior lens capsule rupture (PLCR) during phacoemulsification in enucleated canine eyes. Furthermore, to compare the IOPs between different stages of phacoemulsification for two different bottle heights (BH).

PROCEDURES

Coaxial phacoemulsification was performed using a venturi-based machine at a 60 or 90 cm BH. A pressure transducer, inserted into the anterior chamber through the peripheral cornea, monitored real-time IOP. For one half of the lens, the sculpt-segment removal (SS) was followed by irrigation/aspiration (IA). The PLCR was intentionally created, and the SS and IA were repeated on the residual lens fragments.

RESULTS

For the 60 cm BH, the mean IOP following the PLCR was significantly higher than before the PLCR during SS (28.30 ± 12.56 and 38.71 ± 9.43 mmHg before and after PLCR, respectively) and IA (42.76 ± 12.46 and 47.88 ± 7.10 mmHg before and after PLCR, respectively) stages (P < 0.001). For the 90 cm BH, the mean IOP following the PLCR was also significantly higher than before the PLCR during SS (33.39 ± 11.09 and 58.17 ± 6.89 mmHg before and after PLCR, respectively) and IA (62.39 ± 12.46 and 72.04 ± 8.59 mmHg before and after PLCR, respectively) stages (P < 0.001).

CONCLUSIONS

The occurrence of a PLCR led to an increase in IOP during both the SS and IA stages. The elevated IOP after the PLCR might be one of the most important factors for ocular tissue damage, as it reduces ocular perfusion. Additionally, the BH should be reduced following PLCR to prevent complications stemming from the raised IOP.