Jaegook Lim

Effect of preservative-free tafluprost on intraocular pressure, pupil diameter, and anterior segment structures in normal canine eyes.

OBJECTIVE This study was designed to evaluate the changes in intraocular pressure (IOP), pupil diameter (PD), and anterior segment parameters using ultrasound biomicroscopy (UBM) after instillation of preservative-free (PF) tafluprost in normal dogs. PROCEDURES Six beagle dogs were used. PF tafluprost was instilled in one randomly selected eye, and PF artificial tear was instilled in the other eye (control). IOP and PD were measured every 15 min for the first hour, every 2 h for the next 17 h, and at 24 h and 36 h postinstillation (PI). Anterior segment parameters including geometric iridocorneal angle (ICA), width of the entry of the ciliary cleft (CCW), length of the ciliary cleft, area of the ciliary cleft, and depth of the anterior chamber were measured with UBM before and after PF tafluprost instillation. RESULTS Compared with the control group, IOP was significantly lower from 4 h PI to 24 h PI and PD was significantly smaller from 30 min PI to 18 h PI (P < 0.05). Among UBM parameters, ICA and CCW significantly decreased and increased after PF tafluprost instillation, respectively (P < 0.05). Other parameters showed no significant changes. CONCLUSIONS Instillation of PF tafluprost lowered IOP and induced miosis in normal canine eyes. Alterations in ICA and CCW occurred simultaneously, which probably affected the outflow of aqueous humor. PF tafluprost could be considered an alternative prostaglandin analog in the treatment of canine glaucoma.

Ultrasound biomicroscopic study of the effects of topical latanoprost on the anterior segment and ciliary body thickness in dogs.

OBJECTIVE The goal of this study was to evaluate the effects of topical latanoprost on the anterior segment and ciliary body using ultrasound biomicroscopy (UBM) in dogs. ANIMALS STUDIED This study included six eyes of six clinically normal beagles. PROCEDURES UBM scans were performed on six sedated dogs before and 2 h after topical latanoprost instillation. From the next day on, latanoprost was topically applied twice daily for 7 days. After 1 week of instillation, the UBM scans were repeated. The ciliary body thickness (CBT) and the anterior segment parameters, including the iridocorneal angle (ICA), the width of the ciliary cleft (CC) entry, the length of the CC, and the width of the mid-CC, were measured. RESULTS The topical latanoprost decreased the ICA and CC entry width and increased the mid-CC width without any significant alterations in the CC length. There were time-dependent alterations in the CBT: a reduction in the CBT after 2 h of instillation and rebound thickening after 1 week of instillation. CONCLUSIONS The topical latanoprost widened the ciliary cleft despite the narrowing of the ICA and CC entry. Time-dependent alterations in the CBT were demonstrated by the UBM and might be a reflection of the mechanism of the uveoscleral outflow enhancement induced by the topical latanoprost.

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.

Effects of prostaglandin-mediated and cholinergic-mediated miosis on morphology of the ciliary cleft region in dogs

OBJECTIVE To compare morphology of the ciliary cleft (CC) region in dogs after topical administration of latanoprost, pilocarpine, or a combination of latanoprost and pilocarpine. ANIMALS 6 Beagles. PROCEDURES A prospective 4-phase crossover study with washout periods was performed. Latanoprost (phase L), pilocarpine (phase P), pilocarpine followed by latanoprost (phase PL), and latanoprost followed by pilocarpine (phase LP) were administered to the right eye. Artificial tears were administered to the left eye (control eye). For each phase, pupil diameter and intraocular pressure (IOP) were measured and ultrasonographic biomicroscopy was performed 2 hours after topical treatment. Angle opening distance (AOD), ciliary cleft width (CCW), ciliary cleft length (CCL), and ciliary cleft area (CCA) were evaluated. RESULTS All treated eyes had marked miosis without significant differences in pupil diameter among phases. Significant IOP reductions were detected for all phases, except phase P. The AOD and CCA were significantly increased in all phases for treated eyes, compared with results for control eyes. The CCW was significantly increased in phases P, PL, and LP; CCL was significantly increased in phases PL and LP. Comparison of treated eyes among phases revealed that CCW differed significantly between phases L and P and between phases L and PL. CONCLUSIONS AND CLINICAL RELEVANCE Prostaglandin-mediated and cholinergic-mediated miosis caused variations in CC configurations. When latanoprost and pilocarpine were used in combination, the first drug administered determined the cleft morphology, which was not fully reversed by the second drug. The CC morphology did not fully explain IOP reductions.

Ultrasound biomicroscopy and tonometry in ophthalmologically normal pigeon eyes

OBJECTIVE To evaluate the feasibility of ultrasound biomicroscopy (UBM) and tonometry in pigeons and to provide biometric reference ranges for normal pigeon eyes. ANIMALS STUDIED Ten pigeons (Columba livia var. domestica) with ophthalmologically normal eyes. PROCEDURES Ophthalmic examinations, including slit-lamp biomicroscopy and tonometry, were performed to confirm that the eyes were normal. UBM was then performed on the left eye. On each obtained image, the ciliary cleft (CC) length, CC width, and CC area, and iridocorneal angle (ICA) were measured. RESULTS Richly vascularized iris was observed in all pigeon eyes. Mean intraocular pressure was 11.7 ± 1.6 mmHg, without any statistical difference between the left and right eyes. The UBM scanning procedure was well tolerated in all pigeons. Mean values of CC length, CC width, CC area, and ICA were 1.55 ± 0.17 mm, 0.36 ± 0.05 mm, 0.39 ± 0.04 mm2 , and 15.17 ± 1.06°, respectively. CONCLUSIONS Ultrasound biomicroscopy could be a useful diagnostic tool to evaluate anterior ocular segment of pigeons.