Comparative evaluation of corneal and limbal epithelial thickness in brachycephalic dogs with and without corneal diseases using spectral domain optical coherence tomography.

OBJECTIVE: To evaluate alterations in epithelial thickness during corneal degeneration, corneal pigmentation, and additional features observed through spectral-domain optical coherence tomography (SD-OCT) in brachycephalic dogs. ANIMALS AND PROCEDURES: The study used 55 eyes from 49 brachycephalic dogs that underwent OCT-containing ophthalmic examinations. The examined eyes were classified into corneal degeneration, corneal pigmentation, and normal groups according to corneal lesions. For each eye, corneal epithelial thickness (CET) in the central cornea and maximum limbal epithelial thickness (maxLET) in 4 quadrants of limbus (superior, inferior, nasal, and temporal) were measured from OCT images. Additional abnormal findings on OCT images, including irregular epithelium, subepithelial hyperreflectivity, and conjunctivochalasis, were also recorded. RESULTS: The corneal degeneration group had significantly thinner nasal and temporal maxLETs than that of the normal group (p < .001). In the central corneal OCT image of the corneal degeneration group, an irregular epithelium was observed in 70.6% and subepithelial hyperreflectivity in 82.4%, both of which were significantly higher than the normal group (p < .001). In a comparative analysis, the nasal, temporal, and inferior maxLETs were significantly thinner in the corneal pigmentation group than those in the normal group (p < .001, p < .001, and p = .01, respectively). CONCLUSIONS: Morphological changes in the limbal epithelium were observed in dogs with corneal degeneration and corneal pigmentation. LET reduction could be associated with their pathogenesis and would be valuable as an additional parameter for corneal diseases.

Hyperproliferation of Elschnig pearl-type posterior capsule opacification and spontaneous regression in two pseudophakic canine eyes.

OBJECTIVE: To describe the hyperproliferation of Elschnig pearl-type posterior capsule opacification and concurrent uveitis in two canine eyes after phacoemulsification, followed by spontaneous resolution of the Elschnig pearls. ANIMAL STUDIED: A 10-year-old castrated male Spitz (Case 1) and a 4-year-old spayed female Bichon Frise (Case 2). PROCEDURE: Elschnig pearls proliferating beyond the anterior capsulotomy site were observed in the right eye 10 months after bilateral diabetic cataract surgery (Case 1) and 7 months after unilateral cataract surgery (Case 2). In both cases, hyperproliferation occurred where the anterior capsule did not overlap with the intraocular lens (IOL), and was accompanied by aqueous flare. In Case 1, the pearls extended from the anterior capsule and adhered to the iris, causing focal posterior synechia. No other possible causes of uveitis were apparent. RESULTS: Initially, uveitis severity improved after the administration of topical and systemic anti-inflammatory drugs. However, uveitis recurred when the dosage of anti-inflammatory treatment was reduced. The Elschnig pearls underwent morphological changes throughout the follow-up period. In both cases, the pearls beyond the anterior capsulotomy resolved spontaneously after 5 months. Only a few pearls remained between the IOL and posterior capsule, and no recurrence of pearl proliferation was observed at the last follow-up. CONCLUSIONS: To the best of our knowledge, this is the first report of spontaneous Elschnig pearl regression in dogs. Lens-induced uveitis (LIU) may have been caused by anterior chamber hyperproliferative pearls. LIU associated with hyperproliferative pearls may be managed with appropriate anti-inflammatory treatment and monitoring.

Evaluation of changes in lacrimal canaliculi width depending on temperature and viscosity of eye drops using spectral-domain optical coherence tomography in dogs.

OBJECTIVE: To evaluate the changes in the width of the lower lacrimal canaliculi (LC) upon instillation of artificial tears (AT) at different temperatures and viscosities using spectral-domain optical coherence tomography (SD-OCT). ANIMAL STUDIED: Eight eyes of four client-owned adult dogs. PROCEDURES: Imaging of lower LC was performed under general anesthesia. AT at temperatures of 2°C, 20°C, and 38°C, and a high-viscosity tear gel of 20°C, were topically instilled in 100 µL volumes. SD-OCT tracked LC width changes following each instillation. RESULTS: The average baseline width of the LC was 96.38 ± 30.18 µm. The 2°C AT expanded LC width to 183.50 ± 44.11 µm, returning to baseline in 5.00 ± 1.31 min. The 20°C AT resulted in a width of 155.25 ± 35.79 µm, with a 3.88 ± 1.25 min return. The 38°C AT expanded LC width to 131.75 ± 29.49 µm, with a 2.25 ± 0.89 min return. The high-viscosity tear gel expanded LC width to 208.57 ± 56.31 µm, with remained expanded for 10 or more minutes. In temperature comparisons, the 2°C and 20°C AT significantly expanded the LC width more and had longer return times than the 38°C AT (p < .05). Viscosity comparisons showed higher viscosity eye drops significantly expanded LC width more than lower viscosity eye drops (p < .05). CONCLUSIONS: This study found that lower temperature and higher viscosity of eye drops had tendency to result in a wider expansion of the LC width. Additionally, the return time to baseline for LC width tended to be longer with eye drops of lower temperature and higher viscosity. This finding could be helpful in advancing future research on tear dynamics.

The relationship between corneal calcareous degeneration and various ophthalmic diseases in dogs: A retrospective study.

OBJECTIVE: To investigate ocular factors that influence the development of corneal calcareous degeneration (CCD) in dogs. ANIMALS AND PROCEDURES: The medical records of 96 eyes of dogs with CCD and 288 eyes without CCD were retrospectively reviewed. Dogs with evidence of causative systemic illness associated with CCD were excluded from the study. Logistic regression analysis was used to identify the ocular factors associated with the development of CCD. To identify the effect of phosphate-containing eyedrops on CCD, the application periods of phosphate-containing antiglaucoma eyedrops were compared between the glaucomatous eyes in the CCD and non-CCD groups. RESULTS: Increased age, brachycephalic breed, keratoconjunctivitis sicca, advanced cataract, history of phacoemulsification, and topical corticosteroid application were significantly associated with CCD development. Glaucoma was significantly overrepresented in the non-CCD group, and the application period of phosphate-containing antiglaucoma eyedrops was significantly longer in eyes with CCD than in those without CCD. CONCLUSIONS: Ophthalmic diseases requiring long-term management of ocular inflammation and long-term application of phosphate-containing eyedrops may contribute to the development of CCD. Glaucoma is overrepresented in dogs without CCD, which is thought to be due to the differences in predisposed age and breeds between dogs with glaucoma and CCD.

Unilateral blindness presumed as sudden acquired retinal degeneration syndrome (SARDS) in one Dachshund and four Maltese dogs.

OBJECTIVE: To describe blindness, initially presenting as a unilateral condition and diagnosed as sudden acquired retinal degeneration syndrome (SARDS). ANIMALS STUDIED: One Dachshund and four Maltese dogs presented with unilateral blindness, for which the results of general ophthalmic examinations were insufficient to explain the blindness. All dogs were spayed females. RESULTS: Intraocular pressures were normal, and the optical media of the eyes were clear. Fundus appearances of the initially blind eyes were within normal variations, with slightly attenuated retinal blood vessels in some cases when compared with the sighted contralateral eyes. Electroretinography (ERG) amplitudes of the affected eyes were flat and reduced in the contralateral-sighted eyes in four dogs. One dog underwent ERG after the blindness progressed bilaterally 8 days after initial presentation (despite topical steroid medication). Two dogs had no recheck visits, but phone call follow-ups reported bilateral blindness 3 months later in one dog. One dog received no medication and retained vision in the contralateral eye until the last follow-up (94 days later). One dog received systemic cyclosporine and steroid medications and maintained vision in the contralateral eye; however, regular ERG rechecks showed a trend of declining amplitude (448 days). In this dog, optical coherence tomography (OCT) showed different stages of disorganized retinal layers as well as different retinal thickness between the eyes. CONCLUSIONS: Despite normal-looking fundi, ERG and OCT revealed different degrees of retinal changes between both eyes in this study. Eyes with vision might develop progressive blindness after a substantial amount of time in these presumed SARDS cases.

Sequential Ahmed valve implantation after primary implant surgery in two dogs.

OBJECTIVE: To report the outcomes of sequential Ahmed valve implantation in two dogs with uncontrolled intraocular pressure (IOP) after primary Ahmed valve implantation. ANIMALS STUDIED: A 6-year-old castrated male American Cocker Spaniel (case 1) and a 12-year-old spayed female mixed-breed dog (case 2) presented with glaucoma management in the left eyes of both dogs. PROCEDURES: Primary Ahmed valve implantation was performed because of uncontrolled IOP despite antiglaucoma medications used in both dogs. The IOP was maintained within the normal range for 14 and 2 months after surgery in cases 1 and 2, respectively. In both cases, the IOP gradually increased, which was assumed to be caused by bleb fibrosis. In particular, in case 2, one bleb revision surgery was performed during that period, but it was unsuccessful. Therefore, we decided to perform sequential implantation surgery. RESULTS: In case 1, hyphema occurred the day after sequential surgery and resolved with anti-inflammatory treatment. In case 2, it occurred immediately after the surgery and resolved after surgical blood clot removal. IOP remained below 15 mmHg, and menace response was positive until 40 and 23 months after the sequential surgery in cases 1 and 2, respectively. As a long-term complication, cataracts occurred at 17 months in case 1 and 10 months in case 2. CONCLUSIONS AND CLINICAL RELEVANCE: Sequential implantation surgery in the same eye could be an effective alternative for long-term IOP management and vision maintenance. A better understanding of complications and appropriate postoperative management is essential for better outcomes.

Atypical antibiotic-responsive Staphylococcus pseudintermedius-associated tumor-like meibomitis in the upper eyelid: A case report of two dogs.

OBJECTIVE: To present the clinical signs and treatment methods for atypical tumor-like meibomitis in two dogs. ANIMALS STUDIED: A 4-year-old castrated-male Coton de Tulear (Case 1) and a 6-year-old spayed-female Maltese dog (Case 2). PROCEDURE: Full ophthalmic examination revealed a well-circumscribed, firm, and raised solitary mass on the upper eyelid of the left (Case 1) and right eye (Case 2). Case 1 showed a recurrent mass with a diameter of 2-3 mm, which was excised by the referring veterinarian. The possibility of meibomian gland involvement was suggested histopathologically. Case 2 had a history of blepharitis treated with systemic corticosteroids 4 years ago. RESULTS: Topical and systemic antibiotics and anti-inflammatory drugs were administered to reduce inflammation and prevent secondary infections. In Case 1, the mass appeared static at the beginning of medication; however, after stopping antibiotics while tapering steroids, the mass increased in size and was associated with suppurative discharge. In Case 2, the mass continued to grow despite treatment, showing a similar infection pattern. Cytological examination revealed neutrophilic inflammation with cocci infection, and bacterial culture confirmed the presence of Staphylococcus pseudintermedius in both cases. When steroid administration was stopped and antibiotic administration was initiated according to the results of the antibiotic susceptibility test, the mass rapidly decreased in size and completely disappeared. There was no recurrence on follow-up. CONCLUSIONS: A unilateral antibiotic-responsive tumor-like solitary mass on the upper eyelid resolved without surgical treatment. Medical treatment must be considered when treating atypical eyelid masses, and the use of appropriate antibiotics through antibiotic susceptibility testing is important.

Assessment of corneal and limbal epithelial thickness by spectral-domain optical coherence tomography in brachycephalic and non-brachycephalic dogs.

OBJECTIVE: To investigate the variance in corneal epithelial thickness (CET) and limbal epithelial thickness (LET) according to the age and skull type by using spectral-domain optical coherence tomography (SD-OCT) in normal dogs. ANIMALS AND PROCEDURES: This study used an eye each from 46 dogs (24 brachycephalic and 22 non-brachycephalic dogs) assessed to have clear corneas. Each dog was classified according to age into groups 1 (0-5 years), 2 (6-10 years), and 3 (>11 years). OCT imaging was performed on the central cornea for CET and perpendicular to the quadrant of the limbus for LET. The average of the maximum LET (maxLET) value was measured in four eye quadrants. RESULTS: Corneal epithelial thickness was not significantly different according to age in brachycephalic and non-brachycephalic dogs. Visualization of the limbal invagination was better when the maxLET was thick. Nasal and temporal maxLETs were significantly thicker than superior and inferior maxLETs in non-brachycephalic dogs. In brachycephalic dogs, there was a significant decrease in nasal maxLET with age (rs  = -0.489, p = .015). Significant differences between brachycephalic and non-brachycephalic dogs were observed in nasal maxLET (p = .024) and temporal maxLET (p = .011). CONCLUSIONS: Invagination was better visualized in the nasal and temporal limbal quadrants of non-brachycephalic dogs compared with brachycephalic dogs, and the maxLETs of the regions were thicker than those of the brachycephalic dogs. CET and LET measurements using SD-OCT can help in clinical assessment and research on ocular surface diseases in dogs.

Comparison of iridocorneal angle parameters measured by spectral domain optical coherence tomography and ultrasound biomicroscopy in dogs.

OBJECTIVE: To compare the measurements of iridocorneal angle parameters between spectral domain optical coherence tomography (SD-OCT) and ultrasound biomicroscopy (UBM) in dogs. ANIMALS STUDIED AND PROCEDURES: A total of 47 eyes of dogs were scanned at the temporal limbus using SD-OCT and UBM. Iridocorneal angle (ICA) and angle opening distance (AOD) were measured from the obtained images accordingly. The intra-observer and inter-observer reproducibility were evaluated using the intraclass correlation coefficient. To evaluate intra-observer reproducibility, measurements of the first and second grading from the first examiner were compared. To evaluate inter-observer reproducibility, measurements between the two examiners were compared. Agreement between ICA and AOD for SD-OCT and UBM was evaluated using Bland-Altman plots. RESULTS: In the first grading, the mean ICA and AOD for SD-OCT were 31.4 ± 6.4° and 641.4 ± 270.8 µm, respectively. The mean ICA and AOD for UBM were 32.0 ± 4.8° and 700.4 ± 238.8 µm, respectively. For ICA and AOD measurements, intra-observer reproducibility was excellent for both devices, whereas inter-observer reproducibility was excellent for SD-OCT and good for UBM. The mean difference in ICA between SD-OCT and UBM was 0.6° with a limit of agreement (LoA) span of 18.9°. The mean difference in AOD between SD-OCT and UBM was 58.9 µm with a LoA span of 804.4 µm. CONCLUSIONS: Spectral domain optical coherence tomography is an effective non-contact imaging modality for the evaluation of canine iridocorneal angle parameters in a clinical setting. Reproducibility of measurements obtained is comparable or superior to UBM, but values obtained by SD-OCT and UBM for AOD are not interchangeable between devices.

Evaluation of the upper and lower proximal lacrimal canaliculi using spectral-domain optical coherence tomography in normal Beagle dogs.

OBJECTIVE: To confirm the feasibility of visualizing upper and lower proximal lacrimal canaliculi (LC) using spectral-domain optical coherence tomography (SD-OCT). ANIMALS STUDIED: Eight eyes of four normal Beagle dogs. PROCEDURES: To obtain an upper proximal LC image, the head was turned in the opposite direction to the eye being imaged, and the medial part of the upper eyelid was everted to expose the LC. To obtain a lower LC image, the lower eyelid was everted just below the punctum. Using "angle mode", the scan line was placed parallel on the long axis of the LC. The inlet LC width (LCW) was measured. Artificial tears (AT) were instilled, and LCW was compared before and after AT instillation. Additionally, the return time to the initial LCW inlet width was recorded. RESULTS: Before AT instillation, there was a significant difference between the mean upper and lower LCW (91.8 ± 3.2 µm and 110.1 ± 8.4 µm, respectively). After AT instillation, the mean upper and lower LCW were 236.9 ± 27.7 µm and 238.4 ± 30.4 µm, respectively. Significant differences in the LCW before and after AT instillation in both the upper and lower LCWs were observed. The mean return time of the upper and lower LCW to their initial widths after AT instillation was within 4 min. CONCLUSIONS: Spectral-domain optical coherence tomography was an effective method for providing high-resolution images of the upper and lower proximal LC. This method enables observation of LC changes after instillation of eyedrops in veterinary clinical practice.

The feasibility of clinical evaluation for anterior uveitis through spectral-domain optical coherence tomography in dogs.

OBJECTIVE: To evaluate the clinical application of spectral-domain optical coherence tomography (SD-OCT) for anterior uveitis in dogs. Animals and procedures Client-owned dogs presenting with anterior uveitis and clinically healthy dogs were enrolled in this study. Included eyes were divided into 5 groups by flare grade and 3 groups by cell grade through slit-lamp biomicroscopy. Each eye was examined using SD-OCT following slit-lamp biomicroscopy. The ratio of aqueous signal intensity to air signal intensity, which is called the aqueous-to-air relative intensity (ARI) index, was used to evaluate the flare grade. Cell number, central corneal thickness (CCT), and the presence of keratic precipitates (KPs) were analyzed on SD-OCT. The OCT parameters, including ARI index, cell number, and CCT, were compared to the slit-lamp clinical flare and cell grade. RESULTS: Thirty-six eyes with anterior uveitis and 27 healthy eyes were enrolled. The ARI index showed a significant correlation with clinical flare grade (rs  = 0.811, p < .001). In multiple regression analysis, the ARI index and CCT showed a significant negative correlation (r = -0.258, p = .044). The number of cells on SD-OCT significantly increased with cell grade on slit-lamp biomicroscopy (rs  = 0.653, p < .001). The clinical flare grade and CCT were significantly correlated in the partial correlation analysis after controlling for age (partial correlation coefficient = 0.471, p = .002). KPs were observed in 61% of the eyes with flare using SD-OCT (22/36 eyes). CONCLUSIONS: Spectral-domain optical coherence tomography could provide quantitative information, including the ARI index, cell counts, and CCT in dogs. SD-OCT is an auxiliary modality for slit-lamp biomicroscopy when evaluating anterior uveitis in dogs.

The association of topical flurbiprofen with the incidence of postoperative glaucoma after phacoemulsification in dogs.

OBJECTIVE: To investigate the relationship between topical administration of flurbiprofen plus corticosteroids versus corticosteroids alone following phacoemulsification and the development of postoperative glaucoma in dogs. ANIMAL STUDIED: Thirty-eight/eighty-three (45.8%) eyes were prescribed topical flurbiprofen plus corticosteroids immediately postop while 45/83 (54.2%) eyes received topical corticosteroids alone. PROCEDURES: Logistic regression models were performed to analyze the relationship between topical flurbiprofen and development of glaucoma and to predict potential risk factors for postoperative glaucoma occurrence. RESULTS: Eighty-three eyes (65 dogs) were included. The mean age at surgery was 8.2 years, with even gender distribution. Increasing age at the time of surgery significantly increased the probability of postoperative glaucoma occurrence (odds ratio [OR] = 1.344, 95% confidence interval [CI] 1.093-1.652; p = 0.005). Glaucoma occurred in 17/83 (20.5%) eyes; of these, 15/38 (39.5%) and 2/45 (4.4%) eyes were prescribed topical flurbiprofen plus corticosteroids and topical corticosteroids alone, respectively. Immediate postoperative use of topical flurbiprofen was significantly associated with an increased probability of postoperative glaucoma occurrence (OR = 19.183 [95% CI 3.367-109.286], p = 0.001). CONCLUSIONS: Immediate postoperative use of topical flurbiprofen was a potential predisposing risk factor for the development of glaucoma following phacoemulsification. Restriction of postoperative use of topical flurbiprofen might decrease the possibility of postoperative glaucoma development in dogs.

Comparative intraocular pressure measurements using three different rebound tonometers through in an ex vivo analysis and clinical trials in canine eyes.

OBJECTIVE: To evaluate the clinical relevance of intraocular pressure (IOP) measured with three different rebound tonometers in an ex vivo analysis and clinical trials in dogs. ANIMALS AND PROCEDURES: Ex vivo analysis and clinical trials were performed separately. For the ex vivo analysis, eight enucleated eyes were obtained from four Beagle dogs. IOP values measured with TONOVET® (TV-IOP), TONOVET-Plus® (TVP-IOP), and SW-500® (SW-IOP) were compared with manometric IOPs. For clinical trials, each tonometer was evaluated separately, depending on whether TVP-IOP was higher or lower than 14 mm Hg. One-way repeatedmeasures analysis of variance, simple linear regression analysis, and Bland-Altman plots were used for statistical analyses. RESULTS: In ex vivo analysis, TV-IOP and TVP-IOP were not significantly different from manometric IOP. However, SW-IOP underestimated IOP compared to manometry. Higher discrepancy was observed in TV-IOP and SW-IOP with an increase in manometric IOP. In clinical trials, no significant difference was observed between TV-IOP (9.73 ± 2.92) and TVP-IOP (11.36 ± 2.23) when TVP-IOP was lower than 14 mm Hg, but SW-IOP (8.70 ± 3.03) was significantly lower than TVP-IOP. TV-IOP (15.96 ± 6.47) and SW-IOP (13.09 ± 3.72) were significantly lower than TVP-IOP (20.08 ± 6.60) when the IOP was higher than 14 mm Hg of TVP-IOP. CONCLUSIONS: This study demonstrates that the TONOVET® and TONOVET-Plus® provide a useful approach for ex vivo analysis. In clinical trials, results of TV-IOP and SW-IOP were significantly lower than of TVP-IOP when IOP was higher than 14 mm Hg of TVP-IOP. The characteristics of rebound tonometers should be considered in clinical settings.

Proteomic analysis of aqueous humor in canine primary angle-closure glaucoma in American Cocker Spaniel dogs.

OBJECTIVE: To analyze proteomic profiles of the aqueous humor (AH) of canines with primary angle-closure glaucoma (PACG) and identify associated protein alterations. ANIMALS STUDIED: Six American Cocker Spaniels with PACG and six American Cocker Spaniels without ocular diseases. METHODS: Aqueous humor samples were collected from six American Cocker Spaniels with PACG at Seoul National University, VMTH, and six healthy Cocker Spaniels without ocular disease at Irion Animal Hospital. For the PACG group, AH samples were obtained by anterior chamber paracentesis prior to glaucoma treatment. For the AH control group, AH samples were collected from patients anesthetized for other reasons. Total AH protein concentration was determined by the bicinchoninic acid (BCA) assay. AH protein samples were quantified by liquid chromatography-mass spectrometry (LC-MS/MS). Raw MS spectra were processed using MaxQuant software 30, and the Gene Ontology (GO) enrichment analysis was performed using ClueGO. RESULTS: The AH protein concentration in the PACG group (10.49 ± 17.98 µg/µl) was significantly higher than that of the control group (0.45 ± 0.11 µg/µl; p < .05). A total of 758 proteins were identified in the AH. Several proteins both significantly increased (n = 69) and decreased (n = 252) in the PACG group compared to those in the control group. GO enrichment analysis showed that the "response to wounding," "negative regulation of endopeptidase activity," and "cell growth" pathways were the most enriched terms in the PACG group compared to the control group. The top 5 proteins that were significantly increased in the AH of the PACG group were secreted phosphoprotein 1 (SPP1), peptidoglycan recognition proteins 2 (PGLYRP2), tyrosine 3-monooxygenase (YWHAE), maltase-glucoamylase (MGAM), and vimentin (VIM). CONCLUSIONS: Gene Ontology enrichment analysis using the proteomic data showed that proteins and pathways related to inflammation were significantly upregulated in the various stage of PACG. Proteomic analysis of the AH from the PACG may provide valuable insights into PACG pathogenesis.

Pharmacological inhibition of Kv3 on oxidative stress-induced cataract progression.

Oxidative stress is one of the most important risk factors for cataractogenesis. Previous studies have indicated that BDS-II, a Kv3 channel blocker, plays pivotal roles in oxidative stress-related diseases. This study demonstrates that BDS-II exerts a protective effect on cataractogenesis. Specifically, BDS-II was observed to inhibit lens opacity induced by H2O2. BDS-II was also determined to inhibit cataract progression in a sodium selenite-induced in vivo cataract model by inhibiting reduction of the total GSH. In addition, BDS-II was demonstrated to protect human lens epithelial cells against H2O2-induced cell death. Our results suggest that BDS-II is a potential pharmacological candidate in cataract therapy.

Optical coherence tomography of the Tokay gecko (Gekko gecko) eye.

OBJECTIVE: To provide images of the anterior and posterior structures of the gecko eye using spectral domain optical coherence tomography (SD-OCT). ANIMALS AND PROCEDURES: Eight ophthalmologically normal Tokay geckos (Gekko gecko) were used. The nose-cloaca distance and body weight were measured for each gecko. Tomographic images were obtained using SD-OCT without the use of anesthetic or mydriatic agents. The central corneal thickness (CCT), the anterior chamber depth (ACD), and the length of the conus papillaris (CP) were manually measured using OCT images. The thickness of the retinal nerve fiber layer (RNFL) around the CP and the retinal thickness in all four quadrants (superior, nasal, inferior, and temporal areas) were automatically measured using the OCT software program. RESULTS: The mean values of the nose-cloaca distance and body weight were 13.8 ± 0.9 cm and 41.3 ± 9.0 g, respectively. The mean values of CCT, ACD, and CP length were 177.6 ± 20.9 µm, 1205.0 ± 79.9 µm, and 1546.4 ± 208.8 µm, respectively. The mean value of RNFL thickness was 52.0 ± 8.2 µm, and the superior region was the thickest. The mean value of total retinal thickness was 202.5 ± 9.4 µm, and the temporal region was the thickest. CONCLUSIONS: Tomographic images of the anterior and posterior segments of the living gecko eye could be obtained using the OCT unit. Multiple retinal layers and anatomical features of the CP were identified.

Ophthalmic findings in cinereous vultures (Aegypius monachus).

OBJECTIVE: The aim of the present study was to provide ophthalmic reference values under normal physiological conditions for Aegypius monachus (cinereous vulture). PROCEDURES: Thirty-two eyes of sixteen adult captive cinereous vultures were used for this study. Tear tests and tonometry in conscious and anesthetized states, neuro-ophthalmic tests, measurement of corneal diameter, slit-lamp biomicroscopy, ophthalmoscopy, and funduscopy were performed. RESULTS: Schirmer tear test (STT) value was 11.4 ± 2.6 and 11.5 ± 2.8 mm/min in the right (OD) and left eye (OS), respectively. Phenol red thread test (PRT) values were 22.3 ± 2.1 mm/15 s OD and 22.8 ± 3.0 mm/15 s OS. The results showed a strong correlation between STT and PRT in both eyes. Intraocular pressure (IOP) values were 32.8 ± 6.9 mm Hg OD and 31.9 ± 7.1 mm Hg OS with TonoVet and 20.7 ± 4.5 mm Hg OD and 19.5 ± 4.1 mm Hg OS with Tono-Pen. There were significant differences in IOPs between rebound and applanation tonometry in both OD and OS. Tear production and IOP values showed significant reductions with general anesthesia in both tear tests and both tonometry (P < .001). Horizontal corneal diameter (mm) was 15.56 ± 0.96 OD and 15.56 ± 0.96 OS. Vertical diameter (mm) was 14.13 ± 0.96 OD and 14.06 ± 1.06 OS. The horizontal diameter was significantly longer than vertical diameter (P < .001). CONCLUSIONS: Ocular morphologic information and normal reference range values for various ophthalmic measurements were obtained in clinically healthy cinereous vultures, which can facilitate accurate diagnosis and better management of ophthalmic diseases in cinereous vultures.

Intraocular Pressure Measurement by Rebound Tonometry (TonoVet) in Normal Pigeons (Columba livia).

We evaluated the applicability of a rebound tonometer (TonoVet) in pigeon eyes and established normal reference intraocular pressure (IOP) values in healthy pigeons; 20 eyes of euthanized pigeons were used for calibration of the TonoVet and 48 eyes of 24 adult pigeons were used for measurement of reference IOP. First, IOP of pigeon eyes ex vivo were measured using the 'd' and the 'p' modes of the TonoVet and compared to manometric IOP values from 5 to 80 mm Hg. Then, to establish normal reference values, IOP was measured from clinically normal pigeons in vivo. The 'd' and the 'p' modes of the TonoVet showed a strong linear correlation with the manometric IOP (R2 = .996 and .991, respectively). The obtained regression formulas were: y1 = 0.439x + 2.059 and y2 = 0.330x - 0.673, respectively (y1, 'd' mode of TonoVet; y2, 'p' mode of TonoVet; x, manometric IOP). The 'd' and the 'p' modes consistently measured one-half and one-third of the actual IOP, respectively. Therefore, the formula obtained through the 'd' mode was applied to obtain reference values. The calibrated IOP of normal pigeon eyes was 19.5 ± 4.4 mm Hg. The actual IOP could be calculated using the presented formula. Considering the limitations of the 'p' mode, use of the 'd' mode is more appropriate. Therefore, the TonoVet rebound tonometry under the 'd' mode is a reliable method for measuring IOP in pigeons.

Effect of Three Different Sedatives on Electroretinography Recordings in Domestic Pigeons (Columba livia).

This study was conducted to compare the effects of 3 different sedative agents on electroretinography (ERG) in domestic pigeons (Columba livia). Six pigeons were sedated with alfaxalone, xylazine, and medetomidine at separate times with a 1-week washout period between sedative administration. After sedation with each agent, pigeons underwent the modified ERG protocol adapted from the standardized protocol for dogs. The scotopic mixed rod and cone response was recorded after 20 minutes of dark adaptation, and the photopic cone response and photopic flicker response were recorded after 10 minutes of light adaptation. Either a 1-way analysis of variance or a Kruskall-Wallis test was used to compare the a-wave and b-wave implicit time and amplitude. No significant differences were observed in the scotopic mixed rod and cone response among all 3 sedatives used. Compared with alfaxalone, medetomidine significantly prolonged the a-wave implicit time, depressed the b-wave amplitude of photopic cone response, and prolonged the peak implicit time of the photopic flicker response (P < .05). These results show that medetomidine has a depressant effect on photopic ERG in pigeons at a dosage that produces light sedation.

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.