Extracellular Vesicles Isolated from Equine Adipose-Derived Stromal Stem Cells (ASCs) Mitigate Tunicamycin-Induced ER Stress in Equine Corneal Stromal Stem Cells (CSSCs).

Corneal ulcers, characterized by severe inflammation of the cornea, can lead to serious, debilitating complications and may be vision-threatening for horses. In this study, we aimed to investigate the role of endoplasmic reticulum (ER) stress in corneal stem progenitor cell (CSSC) dysfunction and explore the potential of equine adipose-derived stromal stem cell (ASC)-derived extracellular vesicles (EVs) to improve corneal wound healing. We showed that CSSCs expressed high levels of CD44, CD45, and CD90 surface markers, indicating their stemness. Supplementation of the ER-stress-inducer tunicamycin to CSSCs resulted in reduced proliferative and migratory potential, accumulation of endoplasmic reticulum (ER)-stressed cells in the G0/G1 phase of the cell cycle, increased expression of proinflammatory genes, induced oxidative stress and sustained ER stress, and unfolded protein response (UPR). Importantly, treatment with EVs increased the proliferative activity and number of cells in the G2/Mitosis phase, enhanced migratory ability, suppressed the overexpression of proinflammatory cytokines, and upregulated the anti-inflammatory miRNA-146a-5p, compared to control and/or ER-stressed cells. Additionally, EVs lowered the expression of ER-stress master regulators and effectors (PERK, IRE1, ATF6, and XBP1), increased the number of mitochondria, and reduced the expression of Fis-1 and Parkin, thereby promoting metabolic homeostasis and protecting against apoptosis in equine CSSCs. Our findings demonstrate that MSCs-derived EVs represent an innovative and promising therapeutic strategy for the transfer of bioactive mediators which regulate various cellular and molecular signaling pathways.

Using a smartphone-based digital fundus camera for screening of retinal and optic nerve diseases in veterinary medicine: A preliminary investigation.

BACKGROUND: Ophthalmoscopy is a valuable tool in clinical practice. We report the use of a novel smartphone-based handheld device for visualisation and photo-documentation of the ocular fundus in veterinary medicine. METHODS: Selected veterinary patients of a referral ophthalmology service were included if one or both eyes had clear ocular media, allowing for examination of the fundus. Following pharmacological mydriasis, fundic images were obtained with a handheld fundus camera (Volk VistaView). For comparison, the fundus of a subset of animals was also imaged with a veterinary-specific fundus camera (Optomed Smartscope VET2). RESULTS: The large field of view achieved by the Volk VistaView allowed for rapid and thorough observation of the ocular fundus in animals, providing a tool to visualise and record common pathologies of the posterior segment. Captured fundic images were sometimes overexposed, with the tapetal fundus artificially appearing hyperreflective when using the Volk VistaView camera, a finding that was less frequent when activating a 'veterinary mode' that reduced the sensitivity of the camera's sensor. The Volk VistaView compared well with the Optomed Smartscope VET2. LIMITATION: The main study limitation was the small sample size. CONCLUSIONS: The Volk VistaView camera was easy to use and provided good-quality fundic images in veterinary patients with healthy or diseased eyes, offering a wide field of view that was ideal for screening purposes.

Schirmer tear test-1 with open or closed eyelids: An evaluation in brachycephalic and nonbrachycephalic dogs.

PURPOSE: Assess aqueous tear production when measured with the dogs' eyelids open or closed. METHODS: Thirty healthy dogs (15 Shih Tzus, 15 Labrador retrievers) were recruited. With the order of testing randomized for each dog, two sessions (separated by 30 min) of STT-1 testing were performed with the dogs' eyelids closed or open. Schirmer strip wetness (every 10 s for 60 s) and number of time(s) the strip dislodged during testing were recorded in each eye. Preferred STT-1 method was surveyed via a global Listserv of the veterinary ophthalmology community. RESULTS: STT-1 values were significantly higher in closed versus open eyes in Shih Tzus (18.6 ± 2.7 mm/min vs. 16.3 ± 2.5 mm/min; p = .002) and Labrador retrievers (21.6 ± 2.9 mm/min vs. 17.8 ± 3.2 mm/min, p < .001), findings that were also significant at times <60 s for either breed (p ≤ .004). Schirmer strips dislodged from six dogs with open eyelids and no dogs with closed eyelids. Maximal STT-1 difference with closed versus open eyelids was 13 mm/min in Labrador retrievers and 7 mm/min in Shih Tzus. Survey results from 275 veterinarians showed STT-1 performed with "closed eyelids" (38.5%), "open eyelids" (26.9%), or "never paid attention, sometimes closed, sometimes open" (34.6%). CONCLUSIONS: Eyelids status (closed or open) during STT-1 testing had a significant impact on aqueous tear secretion in brachycephalic and nonbrachycephalic dogs, highlighting the importance of consistency when repeating STT-1 in a canine patient. STT-1 differences are likely due to sustained reflex tearing throughout the test duration when the dogs' eyelids are closed.

Refractive error of canine cataract patients following implantation with three types of intraocular lenses.

OBJECTIVE: To evaluate refractive state outcomes following phacoemulsification and implantation of 3 different intraocular lenses (IOLs). ANIMALS: A prospective, randomized, controlled study was conducted on 43 client-owned dogs undergoing phacoemulsification with IOL implantation. METHODS: Eyes were randomized to receive either an-vision Fo-X (n = 26), an-vision MD8 (18), or I-MED I-LENS (24) IOL. Refraction was measured 1 week, 1 month, and 3 months postoperatively using streak retinoscopy by 2 examiners masked to each other's results. RESULTS: Postoperative refractive outcomes were highly correlated and not significantly different between 2 examiners for all time points (r = 0.97, 0.98, and 1.00; P = .76, .94, and .98, respectively). One week postoperatively, the refractive errors (mean ± SD) for Fo-X, MD8, and I-LENS were -0.14 ± 2.02 diopters (D), 0.97 ± 2.01 D, and 0.15 ± 2.55 D, respectively. One month postoperatively, the refractive errors were 0.35 ± 2.04 D, 0.06 ± 2.41 D, and -0.82 ± 2.20 D, respectively. Three months postoperatively, the refractive errors were -0.16 ± 2.67 D, 1.60 ± 2.99 D, and 0.59 ± 1.51 D, respectively. There were no significant differences in refractive error outcomes between Fo-X, MD8, and I-LENS at 1 week, 1 month, and 3 months postoperatively (P = .16; F(df=2,66)- = 1.89). However, the Fo-X was the only IOL to yield nearly emmetropic outcomes (±0.50 D) at all 3 time points. CLINICAL RELEVANCE: The postoperative refractive states of dogs were not statistically different when comparing 3 types of IOLs at 3 postoperative time points, though the Fo-X was the only IOL to yield nearly emmetropic outcomes at all 3 time points.

Case report: Blindness associated with Learedius learedi trematode infection in a green sea turtle, Chelonia mydas, of the northern Red Sea.

Spirorchiid blood flukes are widespread in sea turtles, causing disease and mortality in their populations, with high prevalence in several ocean basins. Besides being leading parasitic causes of sea turtle strandings in several parts of the world, these infectious agents can cause endocarditis, vasculitis, thrombosis, miliary egg granulomas, and aneurysms, which ultimately may compromise the survival of green sea turtles. More severe cases may also result in multifocal granulomatous meningitis or pneumonia, both of which can be fatal. Herein, we report the first case of severe trematode infection, Caused by Learedius learedi, in a green sea turtle in the northern Red Sea; this infection is associated with bilateral blindness. Necropsy revealed multiple granulomas with intralesional trematode eggs in the optic nerve, eyes, spleen, heart, and lungs. The parasite was identified as Learedius learedi through specific primers of the ribosomal genome and COI sequences obtained from GenBank. Altogether, these findings emphasize the importance of recognizing the systemic nature of this particular fluke infection to ultimately protect the lives of these marine animals and ensure the sustainability of these species in the wild.

Improving rat welfare through the development of a peribulbar anaesthesia technique for ophthalmic procedures: A preliminary study.

Rats are a commonly used animal model for the study of the pathogenesis and novel treatments of glaucoma, which is induced experimentally using invasive, painful procedures. Peribulbar anaesthesia (PBA) is frequently used in people and domestic animals prior to ophthalmic surgeries to provide excellent perioperative analgesia. Our goal was to develop a PBA technique adapted to rat anatomy, improving the welfare of animals used as a model for glaucoma. Eighteen rat cadavers (n = 36 eyes) were used to establish the optimal needle insertion location. Five injection techniques using 0.1 mL/100 g lidocaine 2% and a contrast agent (1:1 volume ratio) were compared via computed tomography (CT). CT images were scored for injectate distribution at four locations: extraconal, intraconal, around the optic nerve and at the orbital fissure (scale 0-8, where 0 = none and 8 = excellent). Median scores using the dorso-medial-75° (5; range 2-6) and medial-canthus (4.5; range 2-8) injection techniques were not different from the dorso-medial-45° (4; range 3-6) technique and were higher (better distribution) compared with mid-ventral (3; range 2-5) and ventro-lateral (2; range 1-3) techniques. The two superior techniques were used in two experimental rats (n = 4 eyes) to determine the volume of bupivacaine 0.5% necessary to affect corneal touch threshold (CTT) and periocular skin sensitivity (PSS). A volume of 0.05 mL/100 g decreased CTT and PSS for several hours, while a larger volume produced excessively long effects. Dorso-medial-75° or medial-canthus PBA using 0.05 mL/100 g bupivacaine are likely to provide ocular and periocular analgesia in rats, with minor transient adverse effects.

A retinoscopic survey of donkeys and goats.

PURPOSE: Assess the refractive states of donkeys and goats. METHODS: Forty-two donkeys and 28 goats were enrolled. The mean ± SD ages were 7.68 ± 7.33 years for donkeys and 4.26 ± 2.33 years for goats. Seven donkeys and one goat were <6 months old. Retinoscopy was performed in alert animals, following cycloplegia in goats but not in donkeys. Normality was determined using the Kolmogorov-Smirnov test. The two primary meridians and two eyes were compared using Pearson's correlation and paired Student's t-tests. The association between refractive states and age was examined using one-way ANOVA in donkeys and a paired Student's t-test in goats. One-sample t-tests were conducted to assess if the refractive error distributions were significantly different from "0". RESULTS: The mean ± SD spherical equivalent (SE) refractive errors of the right and left donkey eyes were -0.80 ± 1.03 D and -0.35 ± 0.95 D, respectively. The majority (86%) of the donkeys had an astigmatic refraction and eight (19%) had anisometropia. The mean SE refractive errors of the right and left goat eyes were -0.15 ± 1.1 D and -0.18 ± 1.2 D, respectively. The majority (54%) of the goat eyes had an astigmatic refraction and five (18%) had anisometropia. The right and left eye SE refractive errors were positively correlated in both species (both p = .9). Age was not correlated with refractive error in both donkeys (p = .09) and goats (p = .6). CONCLUSIONS: Both goats and donkeys are emmetropic.

The 100 most-cited articles published in the Veterinary Ophthalmology journal between 1998 and 2022: A bibliometric study.

PURPOSE: The aim of this study was to bibliometrically analyze the 100 most-cited articles published in the Veterinary Ophthalmology (VO) journal. METHODS: Web of Science was searched for citations of VO articles published in 1998-2022. Tissue and species studied, and first and last author domicile and affiliation were recorded for the 100 most-cited articles and descriptively analyzed. RESULTS: Altogether, the 100 most-cited VO articles have cited a total of 5483 times. Most commonly, these were devoted to the cornea (23%), multiple tissues (19%), and glaucoma (16%). Studies on dogs (36%), horses (17%), and multiple species (15%) were most often cited. Most first/last authors were from the USA (n = 113), Brazil (n = 13), and France and Germany (n = 7 each), and most frequently affiliated with the University of Florida (n = 36), University of Wisconsin-Madison (n = 15), and Animal Health Trust, North Carolina State University, and Ohio State University (n = 6 each). KN Gelatt (n = 9), DE Brooks (n = 6), and FJ Ollivier and EO MacKay (n = 5 each) were the most frequent first or last authors. The greatest number of citations was for articles with KN Gelatt (n = 555), FJ Ollivier (n = 411), and DE Brooks (n = 372) as first or last authors. "The comparative morphology of the tapetum lucidum" by FJ Ollivier et al. (2002) is the most frequently cited article in VO history (n = 178). CONCLUSIONS: This study provides insight into the impact of publishing in VO and a more comprehensive understanding of trends and the most influential contributions to VO.

Azithromycin and Sildenafil May Have Protective Effects on Retinal Ganglion Cells via Different Pathways: Study in a Rodent Microbead Model.

Decreased blood flow to the optic nerve (ON) and neuroinflammation are suggested to play an important role in the pathophysiology of glaucoma. This study investigated the potential neuroprotective effect of azithromycin, an anti-inflammatory macrolide, and sildenafil, a selective phosphodiesterase-5 inhibitor, on retinal ganglion cell survival in a glaucoma model, which was induced by microbead injection into the right anterior chamber of 50 wild-type (WT) and 30 transgenic toll-like receptor 4 knockout (TLR4KO) mice. Treatment groups included intraperitoneal azithromycin 0.1 mL (1 mg/0.1 mL), intravitreal sildenafil 3 µL, or intraperitoneal sildenafil 0.1 mL (0.24 µg/3 µL). Left eyes served as controls. Microbead injection increased intraocular pressure (IOP), which peaked on day 7 in all groups and on day 14 in azithromycin-treated mice. Furthermore, the retinas and ON of microbead-injected eyes showed a trend of increased expression of inflammatory- and apoptosis-related genes, mainly in WT and to a lesser extent in TLR4KO mice. Azithromycin reduced the BAX/BCL2 ratio, TGFß, and TNFα levels in the ON and CD45 expression in WT retina. Sildenafil activated TNFα-mediated pathways. Both azithromycin and sildenafil exerted a neuroprotective effect in WT and TLR4KO mice with microbead-induced glaucoma, albeit via different pathways, without affecting IOP. The relatively low apoptotic effect observed in microbead-injected TLR4KO mice suggests a role of inflammation in glaucomatous damage.

Accuracy of data in abstracts of veterinary ophthalmology research articles published in peer-reviewed journals.

OBJECTIVE: Assess the accuracy of abstracts in published veterinary ophthalmology articles. PROCEDURES: Abstracts and contents of 204 original research articles in veterinary ophthalmology published in seven peer-reviewed journals between 2016-2020 were reviewed. Abstracts were considered inconsistent if they contained data that were either missing from or inconsistent with corresponding data in the article's body. Each abstract was graded between 0 (inaccurate) to 3 (accurate), and each inconsistency was subjectively classified as minor or major. The influence of selected variables was assessed: journal, impact factor, year of publication, number of words in abstract, study type (prospective/retrospective), and characteristics of the corresponding author [institution (academia/private practice), country of domicile (native/non-native English), number of publications]. RESULTS: Most abstracts were accurate, with 1%, 4%, 9% and 86% receiving a score of 0, 1, 2 and 3, respectively. When detected, most inconsistencies were considered minor (77%). Although not statistically significant (p ≥ .130), the proportion of articles with a perfect score (=3) was higher in prospective (88%) vs. retrospective (81%) studies, academia (88%) vs. private practice (78%), and studies from corresponding authors domiciled in English (89%) vs. non-English (83%) speaking countries. A significant but very weak (r = -0.15 to -0.19; p ≤ .034) negative correlation was found between accuracy score and number of words, as well as 1-year and 5-year impact factors. CONCLUSIONS: Although relatively uncommon, data in abstracts that are inconsistent or missing from the article's body do occur in veterinary ophthalmology articles, and could adversely influence a reader's interpretation of study findings.

Retrospective evaluation of pre-surgical electroretinography results in a mixed-breed canine population presented for cataract removal surgery.

OBJECTIVE: Electroretinography (ERG) is used prior to cataract removal surgery to assess retinal function. We aimed to replicate and improve upon previous studies by performing a full ECVO protocol and by examining the retina post-surgery in all patients. ANIMALS STUDIED: One hundred twenty-seven eyes from 67 dogs were included in the study. PROCEDURES: A full ECVO protocol electroretinography, which includes extensive rod and cone analysis, was performed on all dogs presenting for cataract surgery. RESULTS: Our main findings were that amplitudes, but not implicit times of rod responses decreased with advanced cataracts. Amplitudes of the single flash rod and rod flicker responses were significantly lower in eyes with mature cataracts, and the former also decreased in hypermature cataracts. Cone flicker amplitude responses were also significantly lower in eyes with mature and hypermature cataracts. However, mixed single flash rod-cone and cone responses, with the exception of the mixed rod-cone a-wave amplitude in eyes with hypermature cataracts, were unaffected by cataract stage. The b-wave amplitude of the scotopic, mixed rod-cone, and photopic cone responses were affected by age and decreased by an average of 2.9, 7.5, and 1.5 µV/year, retrospectively (p < 0.01). CONCLUSIONS: Lower ERG amplitudes in canine cataract patients may result from aging or the presence of advanced cataracts and may not indicate the presence of retinal disease.

Effect of anesthetic induction with propofol, alfaxalone or ketamine on intraocular pressure in cats: a randomized masked clinical investigation.

OBJECTIVE: To compare the effect of propofol, alfaxalone and ketamine on intraocular pressure (IOP) in cats. STUDY DESIGN: Prospective, masked, randomized clinical trial. ANIMALS: A total of 43 ophthalmologically normal cats scheduled to undergo general anesthesia for various procedures. METHODS: Following baseline IOP measurements using applanation tonometry, anesthesia was induced with propofol (n = 15), alfaxalone (n = 14) or ketamine (n = 14) administered intravenously to effect. Then, midazolam (0.3 mg kg-1) was administered intravenously and endotracheal intubation was performed without application of topical anesthesia. The IOP was measured following each intervention. Data was analyzed using one-way anova and repeated-measures mixed design with post hoc analysis. A p-value <0.05 was considered significant. RESULTS: Mean ± standard error IOP at baseline was not different among groups (propofol, 18 ± 0.6; alfaxalone, 18 ± 0.7; ketamine, 17 ± 0.5 mmHg). Following induction of anesthesia, IOP increased significantly compared with baseline in the propofol (20 ± 0.7 mmHg), but not in the alfaxalone (19 ± 0.8 mmHg) or ketamine (16 ± 0.7 mmHg) groups. Midazolam administration resulted in significant decrease from the previous measurement in the alfaxalone group (16 ± 0.7 mmHg), but not in the propofol group (19 ± 0.7 mmHg) or the ketamine (16 ± 0.8 mmHg) group. A further decrease was measured after intubation in the alfaxalone group (15 ± 0.9 mmHg). CONCLUSIONS AND CLINICAL RELEVANCE: Propofol should be used with caution in cats predisposed to perforation or glaucoma, as any increase in IOP should be avoided.

Histological and molecular characterization of glaucoma model induced by one or two injections of microbeads to the anterior chamber of mice.

PURPOSE: To characterize glaucoma-induced damage following injections of plastic microbeads into the anterior chamber of mice. METHODS: Mice were divided into three groups: a single plastic microbeads injection (n = 21); two consecutive plastic microbead injections to the right eye at 1-week intervals, 4 of which with two consecutive saline injections in the left eye (n = 15); and an additional control group of two consecutive saline injections at 1-week intervals (n = 6). Intraocular pressure (IOP) was measured weekly. Retinal thickness, ganglion cells (RGCs) and axonal loss, inflammatory and gliosis reactions were measured at week four. Molecular analysis using qRT-PCR in the microbeads injection groups focused on expression levels of inflammation and glaucoma-related genes. RESULTS: Mean IOP following single injection at 4 weeks was significantly elevated compared to baseline in injected eyes (14.5 ± 3.3 mmHg vs. 11.1 ± 2.5 mmHg, respectively, p = 0.003) and not in fellow eyes (13.2 ± 2.9 mmHg vs. 12.2 ± 2.9, respectively, NS). Six (35.3%) bead-injected eyes had IOP ≥ 17 mmHg compared with 2 (11.8%) saline-injected control eyes. Retinal thickness in injected and fellow eyes was 193.7 ± 15.5 µm and 223.9 ± 15.5 µm, respectively (p = 0.03). RGC loss in injected and fellow eyes was 16.0 ± 0.5 and 17.6 ± 0.7 cells per 200 µm, respectively (p = 0.005). Retinal gliosis, axonal loss and inflammatory cell infiltration to the bead-injected eyes were noted. Molecular analysis following double injection showed STAT3 expression decreased in the glaucoma-induced optic nerves (0.69 ± 0.3 vs. 1.16 ± 0.3, p = 0.04), but increased in the glaucoma-induced retinae (p = 0.05) versus saline; retinal IL-1ß decreased significantly (0.04 ± 0.04 vs. 0.36 ± 0.2, p = 0.02). TNF-α, NFkB and SOD-1 expression did not change. CONCLUSION: One/two injections of microbeads elevated IOP, with measurable neuronal damage. An inflammatory response was detected in the injured retina and optic nerve. The therapeutic significance of these findings should be explored.

The dose-dependent effect of a stabilized cannabidiol nanoemulsion on ocular surface inflammation and intraocular pressure.

Cannabidiol (CBD) is a phytocannabinoid that has a great clinical therapeutic potential. Few studies have been published on its efficacy in ocular inflammations while its impact on intraocular pressure (IOP), a major risk factor for glaucoma, remains unclear. Moreover, due to its lability and high lipophilicity, its formulation within a prolonged stable topical ophthalmic solution or emulsion able to penetrate the highly selective corneal barrier is challenging. Therefore, various CBD nanoemulsions (NEs) were designed and evaluated for stability in accelerated conditions. Further, the optimal formulation was tested on a murine LPS-induced keratitis inflammation model. Lastly, increasing CBD concentrations were topically applied, for two weeks, on mice eyes, for IOP measurement. CBD NEs exhibited optimal physicochemical characteristics for ocular delivery. A specific antioxidant was required to obtain the stable, final, formulation. In vivo, 0.4 to 1.6% CBD w/v reduced the levels of key inflammatory cytokines, depending on the concentration applied. These concentrations decreased or did not affect the IOP. Our results showed that a well-designed CBD ocular dosage form can be stabilized for an extended shelf life. Furthermore, the significant decrease in inflammatory cytokines levels could be exploited, provided that an adequate therapeutic dosage regimen is identified in humans.

Mucoadhesive Polymers Enhance Ocular Drug Delivery: Proof of Concept Study with 0.5% Tropicamide in Dogs.

Purpose: To assess the efficacy of 0.5% tropicamide applied after topical administration of 1.4% hydroxyethyl cellulose (HEC) or 1.2% hyaluronic acid (HA) at different time intervals. Methods: Eleven healthy Labrador retriever dogs were used. The study consisted of 7 trials in which pupil diameter (PD) was measured every 30 min for 7 h after drug administration. In trial 1, PD was measured after tropicamide application (control). In trials 2-7, PD was measured after treatment with tropicamide 10 s, 1 and 5 min after application of HEC or HA. Data were analyzed using analysis of variance and post hoc Holm-Sidak tests. Results: Maximal PD (mean ± standard deviation) was significantly greater (P < 0.001) in 5 of 6 experimental trials, with the greatest PD recorded when HEC was applied 1 min (12.2 ± 0.4 mm) and HA 10 s (12.3 ± 0.5 mm) before tropicamide, compared with 11.2 ± 0. 7 mm in control trial 1. PD >10 mm was maintained for 2.75-5 h in trials 2-7 and 2.25 h in trial 1 (P < 0.001). Area under the PD-time curve ranged from 61.9 to 71.3 ± 2.9 mm·hours in trials 2-7, significantly greater than 59.3 ± 1.8 mm·hours in control trial 1 (P ≤ 0.031). Conclusions: Tropicamide efficacy was enhanced by prior administration of a mucoadhesive polymer. Additional studies are needed to determine if HEC and HA of varying concentrations similarly extend and potentiate the effect of other topical ophthalmic drugs in canine eyes.

Is it necessary to wait several minutes between applications of different topical ophthalmic solutions? A preliminary study with tropicamide eye drops in healthy dogs.

OBJECTIVE: To evaluate the efficacy of topical tropicamide when placed at different time intervals before or after a saline drop. ANIMALS STUDIED: Eight healthy Labrador and golden retriever dogs. PROCEDURES: The effect of 1% tropicamide on pupillary diameter (PD) was measured over 240 min when administered alone (control) and then 1 and 5 min prior to, or following, application of a saline drop, with 1-week washout between each of the five trials. Data were analyzed using repeated-measures ANOVA and Tukey post hoc test. RESULTS: Only 6/110 pairwise comparisons among the 5 trials were statistically significant (p ≤ .035), with post-hoc analysis showing no significant differences (p ≥ .14) between the overall means of all trials. In all five trials, maximal PD was reached 30 min after tropicamide application and maintained until 210 min for 180 min (p = .0005). CONCLUSIONS: Our results suggest that waiting 1 min between applications of different ophthalmic solutions may be sufficient for maximal drug effect. Care should be taken when extrapolating these results to other species and different ophthalmic formulations.

Treatment with chloroquine is retinotoxic in captive African penguins (Speniscus demersus). Attenuation and recovery of electroretinographic responses.

PURPOSE: To evaluate the effect of prophylactic anti-malarial chloroquine treatment, and its cessation, on electroretinographic (ERG) responses of captive African penguins. METHODS: A brief ERG protocol ("QuickRetCheck") was recorded under mesopic conditions with manual restraint and no sedation or pupil dilation. Birds were recorded on two separate occasions, first while being treated with a daily chloroquine dose of 10 mg/kg for 12 days (n = 15, treatment group) and second after 4 months without chloroquine treatment (n = 6, off-treatment group). Three birds were recorded on both occasions. Three other birds from the flock that died were studied histopathologically. RESULTS: Scotopic responses were unmeasurable in either recording and therefore were not analyzed. Mean a- and b-wave amplitudes of the mixed rod-cone responses to standard (3 cd·s/m2 ) and high (10 cd·s/m2 ) intensity flashes were higher in the off-treatment group. No difference in implicit times was observed. Sex, age, and number of previous chloroquine treatments did not affect ERG responses. Histopathology revealed Plasmodium spp.in the lungs, liver, and brain, but not in the eyes, of the necropsied birds, and there were no signs of retinitis or retinopathy. CONCLUSIONS: Daily chloroquine treatment was associated with attenuated ERG responses in penguins, which improve following cessation of treatment. Further work is warranted to establish a chloroquine dose that is efficacious yet has minimal adverse effects. Our results suggest that ERG responses of captive penguins undergoing ERG for any indication (such as prior to cataract surgery), must be evaluated in light of the birds' anti-malaria treatment status.

Does the order of intraocular pressure measurement affect tonometry results?

PURPOSE: To determine whether the order of intraocular pressure (IOP) measurement affects readings, regardless of which eye is measured first. METHODS: Intraocular pressure was measured in 31 and 41 dogs using applanation and rebound tonometry, respectively. Initially, IOP was measured in the first (randomly chosen) eye (reading A), followed by measurement in the fellow eye (reading B), and a third (repeated) measurement in the first eye (reading C). After 15 minutes, measurements were repeated in reverse order (readings D - F). RESULTS: Applanation tonometry revealed significant differences between readings A & B (15.6 ± 2.3 and 14.8 ± 2.7 mm Hg, respectively, p = .02), A & C (15.6 ± 2.3 and 14.5 ± 2.4 mm Hg, respectively, p = .002), D & E (14.5 ± 2.3 and 13.7 ± 2.1 mm Hg, respectively, p = .02), D & F (14.5 ± 2.3 and 13.9 ± 1.9 mm Hg, respectively, p = .05), and A & E (15.6 ± 2.3 and 13.7 ± 2.1 mm Hg, respectively, p = .001). Rebound tonometry yielded similar results, with additional differences between B & C (19.1 ± 3.0 and 18.2 ± 2.4 mm Hg, respectively, p = .002) and E & F (18.7 ± 3.3 and 18.2 ± 3.3 mm Hg, respectively, p = .02). CONCLUSIONS: Intraocular pressure measured in the first eye, whether right or left, is higher than in the fellow eye. Repeated tonometry in the same visit could result in a significant IOP decrease, though the magnitude may not be clinically appreciable.

Atypical free-floating iridociliary pigmented epithelial cysts and secondary glaucoma in a caiman (Caiman latirostris).

We describe a case of chronic ocular trauma that resulted in fixed and free-floating, pigmented epithelial iridociliary cysts, inflammation, and secondary glaucoma in a caiman (Caiman latirostris). A 20- to 25-year-old male caiman was presented with phthisis bulbi in the right eye, and congested episcleral vessels, corneal leukoma, disorganized anterior chamber, multifocal anterior synechia, and elevated intraocular pressure in the left eye. Ocular ultrasound of the left eye revealed round structures dispersed in the anterior and posterior chambers and vitreous cavity. Bilateral enucleation was performed, and gross pathology of the left eye revealed multiple pigmented cysts attached to the iris and posterior corneal surface causing marked distortion of the anterior uvea, and free-floating in the vitreous cavity. Histopathology demonstrated heavily pigmented cystic structures of iridociliary epithelium origin carpeting the anterior segment surfaces and causing obstruction of the iridocorneal angles, leading to secondary glaucoma. To the authors' knowledge, this is the first report of iridociliary cysts in wildlife species.