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The aim of the study is to assess the lacrimal gland tear production, using the Schirmer Tear Test (STT), in healthy sheep under general anesthesia and to explore the effects of applying 1% hyaluronic acid ophthalmic gel during general anesthesia. While STT values during anesthesia have been well documented in small animals such as cats and dogs, there seems to be a lack of information available for ruminants like sheep. This gap in the literature highlights the need for further research and exploration into tear production in sheep under anesthesia. The experimental research conducted on twelve adults female sheep provided valuable insights into tear production under anesthesia. By assessing tear production at various key time points the study was able to capture the changes in tear production throughout anesthesia and revealed a significant decrease in Schirmer Tear Test values in all sheep, following general anesthesia. The results showed that closing and taping the eye yielded determined better outcomes compared to administering a 1% lubricant ophthalmic gel. This finding suggests that eye care during anesthesia can impact tear production in sheep. [ABSTRACT FROM AUTHOR]

Background: We evaluate the relationship between corneal nerve structure and function in a veteran population. Methods: 83 veterans (mean age: 55 ± 5 years) seen at the Miami Veterans Affairs (VA) eye clinic were included in this study. Each individual filled out questionnaires to evaluate ocular symptoms (5-Item Dry Eye Questionnaire, DEQ5; Ocular Surface Disease Index, OSDI) and ocular pain (Numerical Rating Scale, NRS; Neuropathic Pain Symptom Inventory modified for the Eye, NPSI-Eye). The individuals also underwent an ocular surface examination that captured functional nerve tests including corneal sensation, corneal staining, and the Schirmer test for tear production. Corneal sub-basal nerve analysis was conducted using in vivo confocal microscopy (IVCM) images with corneal nerve density, length, area, width, and fractal dimension captured. IVCM and functional corneal metrics from the right eye were examined using correlational and linear regression analysis. Results: Most corneal structural metrics were not related to functional metrics, except for weak correlations between various IVCM metrics and tear production. In addition, corneal nerve fiber area was positively related to corneal sensation (r = 0.3, p = 0.01). On linear regression analyses, only the corneal fractal dimension remained significantly related to tear production (β = −0.26, p = 0.02) and only the corneal nerve fiber area remained significantly related to corneal sensation (β = 0.3, p = 0.01). Conclusions: Most corneal nerve structural metrics did not relate to functional metrics in our veteran population, apart from a few weak correlations between structural metrics and tear production. This suggests that using corneal nerve anatomy alone may be insufficient for predicting corneal function. [ABSTRACT FROM AUTHOR]

Simple Summary: Normal values of tear production (STT) and intraocular pressure (IOP) are important values resulting from ophthalmic examinations in animals, but so far there are no data from conscious red deer. The establishment of reference value ranges specific to conscious animals may be useful to institutions in settings where chemical immobilization is not necessary for the examination of the species. A total of 60 red deer were examined in this study. Both eyes of all red deer underwent a complete ophthalmic examination, including evaluation of tear production with the Schirmer tear test and IOP readings. The mean ± standard deviation of STT values were 18.35 ± 4.54 mm/30 s in the right eye and 17.87 ± 4.12 mm/30 s in the left; for both eyes, 18.11 ± 4.33 mm/30 s, with a reference range of 17.33–18.89 mm/30 s. IOP was as follows: 26.96 ± 4.42 mmHg in the right eye and 26.67 ± 3.80 mmHg in the left; for both eyes, 26.81 ± 4.11 mmHg, with a reference range of 26.07–27.55 mm/30 s. No statistically significant differences were found between the right and left eye in terms of IOP and STT values. This study provides the normal range for STT and IOP in healthy red deer. It demonstrates that STT is a practical method for determining tear production, and rebound tonometry is a practical method for evaluating IOP in ophthalmic examinations of deer. Normal values of tear production (STT) and intraocular pressure (IOP) have not been reported in conscious red deer to date. The objective was to determine the normal range of STT and IOP in clinically healthy, conscious red deer (Cervus elaphus) by utilizing a chute restraint. A total of 60 red deer were examined in this study. Both eyes of all red deer underwent a complete ophthalmic examination, including evaluation of tear production with the Schirmer tear test (STT) and assessment of intraocular pressure (IOP) with rebound tonometry, employing the TonoVet® device. The mean ± standard deviation of STT values were 18.35 ± 4.54 mm/30 s in the right eye and 17.87 ± 4.12 mm/30 s in the left; for both eyes, 18.11 ± 4.33 mm/30 s, with a reference range of 17.33–18.89 mm/30 s. IOP was as follows: 26.96 ± 4.42 mmHg in the right eye and 26.67 ± 3.80 mmHg in the left; for both eyes, it was 26.81 ± 4.11 mmHg, with a reference range of 26.07–27.55 mm/30 s. No statistically significant differences were observed between the IOP and STT values of the right and left eyes. This study provides a reference range for the STT and IOP in healthy red deer, showing that STT determination of tear production, and rebound tonometry to evaluate the IOP methods, are practical methods for ophthalmic examination in deer. [ABSTRACT FROM AUTHOR]

Simple Summary: In veterinary medicine, the use of sedative agents to perform clinical and diagnostic procedures is increasingly common. Several anesthetic drugs decrease tear flow production. In recent years, interest in the clinical efficacy of sedative and hypnotic agents for new and atraumatic routes of administration has increased. Tear film production has never been investigated in cats who received sedative agents by the intrarectal route (IR). The aim of this study is to compare the clinical effects of a mixture of dexmedetomidine, ketamine and midazolam on tear film flow administered by the IR versus the intramuscular route (IM). Cats are often easily stressed and uncooperative. The use of sedative agents in the feline species is widely used to perform even minor clinical and diagnostic procedures. The aim of this study is to assess the impact on tear film production of the intrarectal route (IR) administration of a mixture of dexmedetomidine, ketamine and midazolam in comparison with the intramuscular (IM) one. A group of twenty cats were involved in a randomized and blinded clinical trial. A clinical and ophthalmological examination was conducted on the cats. The IR group received dexmedetomidine 0.003 mg kg−1, ketamine 4 mg kg−1 and midazolam 0.4 mg kg−1; the IM group received dexmedetomidine 0.003 mg kg−1, ketamine 2 mg kg−1 and midazolam 0.2 mg kg−1. A Shirmer tear test I (STT- I) was conducted 1 h before sedation and 2′, 10′, 20′, 30′, 40′, and 80′ post drug administration. The reaction to STT-I administration was also evaluated. The IM group has a lower mean tear production than the IR group for all time points evaluated. Cats in the IM group showed less reaction to STT-I administration. This study may suggest that the effect of sedative agents administered by the IR route has a lower incidence on tear production than the IM one. The use of eye lubricant is recommended in any case. [ABSTRACT FROM AUTHOR]

The general anesthesia or sedation reduces both the tear production and the stability of tear film that protect corneal surface, predisposing itself to the exposure keratopathy. The aim of the present study was to evaluate the effects of intramuscular dexmedetomidine (DEX) on canine tear production, measured by standardized Schirmer Tear Test 1 (STT-1) strips, for the 8 h following sedation, in dogs. A significant effect of time on canine tear production was found, highlighting that dexmedetomidine sedative protocol significantly affects tear production in dogs. It is recommended to treat the canine eyes with tear substitutes to protect ocular surface health and the welfare of the dogs. The ocular lubrication should be performed during and up to 12 h after sedation. The present report could provide preliminary information to better understand the effect of DEX on the tear film dynamics. Tear film provides lubrication and protection to the ocular surface. The sedation reduces tear production, often leading to perioperative exposure keratopathy. The aim of the present study was to report the effects of intramuscular dexmedetomidine on canine tear production, measured by STT-1, for an experimental period of 8 h after sedation. Ten dogs who underwent sedation for routine radiologic assessment were recruited for the study. In all animals, tear production in right and left eyes was measured 15 min before sedation (T0: basal values) and 20 min (T20), 1 h (T1), 2 h (T2), 4 h (T4) and 8 h (T8) after drug administration. Analysis of variance and post hoc Bonferroni test (p < 0.05) were performed. A significant effect of time on canine tear production was found. The tear production returned to basal values at T8. So, it is recommended to treat the canine eyes with tear substitutes during and up to 12 h after sedation. [ABSTRACT FROM AUTHOR]

Simple Summary: Different sedatives and anesthetic drugs have been reported to cause adverse ocular side effects, such as an exposure keratopathy due to loss of eyelid reflex, lagophthalmos, reduced stability of the tear film and decreased basal tear production. In the present study, the effects of two sedation protocols, acepromazine (ACP) and acepromazine–methadone (ACP–MET) combination, on tear production measured by the Schirmer Tear Test (STT) 1 on canine eyes were investigated, hypothesizing that both sedation protocols cause a reduction in canine tear production for a variable time. A significant decrease in tear production until 2 h after drug administration compared to basal tear values was observed in the ACP experimental protocol, while in the ACP + MET protocol, this reduction persisted until 8 h. In the ACP + MET group, after 40 min, 100% of dogs showed STT 1 readings lower than 15 mm/min, which could predispose them to corneal injuries. The major reduction in tear production due to the ACP + MET protocol proves the need for adequate corneal hydration, particularly to discourage its use in animals with altered tear production. The purpose of the current study was to investigate the effects of two commonly used sedation protocols in dogs, acepromazine (ACP) and acepromazine–methadone (ACP–MET) combination, on tear production measured by the Schirmer Tear Test (STT) 1. We hypothesized that both sedation protocols cause a reduction in canine tear production for a variable time. Fifteen client-owned dogs were recruited for the study. Each dog was subjected to sedation twice, 2–3 weeks apart, and they were randomly allocated to one of two groups receiving ACP (0.015 mg kg−1) or ACP–MET (0.010 mg kg−1 and 0.2 mg kg−1) intramuscularly. In both eyes, tear production was measured 15 min before sedation (T0) and 20 min (T20 m), 40 min (T40 m), 1 h (T1), 2 h (T2), 4 h (T4) and 8 h (T8), after drug administration. Two-way repeated measures ANOVA, followed by the Bonferroni post hoc test (p < 0.05), showed a significant effect of time (p < 0.0001) and treatment (p < 0.0001). A significant decrease in tear production at T20 m, T40 m, T1 and T2 compared to T0 was observed in the ACP experimental protocol, while in the ACP + MET protocol, this reduction persisted until T8. Comparing the two experimental protocols, no statistically significant differences were observed at T0 or T20 m, and STT 1 values were statistically lower in the ACP + MET than the ACP protocol at the other data points. In the ACP + MET group, at T40 m, 100% of dogs showed STT 1 readings lower than 15 mm/min. This finding is clinically relevant as it can predispose dogs to corneal injuries. The major reduction in tear production due to the ACP + MET protocol proves the need for adequate corneal hydration, particularly to discourage its use in animals with altered tear production. The data obtained provide important information helping clinicians to better manage the drug's effects on tear production. [ABSTRACT FROM AUTHOR]

Simple Summary: In Italy, chickens are used for egg production and as courtyard/domestic animals and consequently veterinarians need to know their general and specialist characteristics. One key area is normal ocular measurements in order to understand any pathological changes affecting the eyes. For an accurate diagnosis and better management of ophthalmic diseases in chickens, this paper describes the normal values for the evaluation of ocular tear production, intraocular pressure, and biometric measurements of the eyes and on the microbial and cultural flora normally present in the conjunctival sac in two Italian chicken breeds. Given the abundance of chickens in Italy, it is important for veterinarians to know the normal state of chickens' eyes in order to identify any ophthalmic pathological changes. The aim of this study was to determine the normal values of select ocular parameters and to evaluate conjunctival microflora in two Italian chicken breeds. Sixty-six healthy chickens underwent a complete ophthalmic examination, which included a phenol red thread test (PRTT) for the evaluation of tear production and the assessment of intraocular pressure by rebound tonometry. B-mode ultrasound biometric measurements and conjunctival microflora identification were also performed in twenty-seven chickens. Mean PRTT was 23.77 ± 2.99 mm/15 s in the Livorno breed and 19.95 ± 2.81 mm/15 s in the Siciliana breed. Mean intraocular pressure was 14.3 ± 1.17 mmHg in the Livorno breed and 14.06 ± 1.15 mmHg in the Siciliana breed. Reference ranges for morphometric parameters were reported in the two breeds. Twenty-three chickens (85.18%) were bacteriologically positive. Chlamydia spp. antigen was detected in 14.81% of chickens. No positive cultures were obtained for fungi. Normal reference range values for selected ophthalmic parameters were obtained in clinically healthy chickens, which could facilitate accurate diagnosis and better management of ophthalmic diseases in these animals. [ABSTRACT FROM AUTHOR]

Particulate matter 2.5 (PM2.5) may aggravate dry eye disease (DED). Corni Fructus (CF), which is fruit of Cornus officinalis Sieb. et Zucc., has been reported to have various beneficial pharmacological effects, whereas the effect of CF on the eye is still unknown. Therefore, in this study, we investigated the effect of oral administration of water extract of CF (CFW) on the eye, hematology, and biochemistry in a DED model induced by topical exposure to PM2.5. Furthermore, the efficacy of CFW compared with cyclosporine (CsA), an anti-inflammatory agent, and lutein, the posterior eye-protective agent. Sprague-Dawley rats were topically administered 5 mg/mL PM2.5 in both eyes four times daily for 14 days. During the same period, CFW (200 mg/kg and 400 mg/kg) and lutein (4.1 mg/kg) were orally administered once a day. All eyes of rats in the 0.05% cyclosporine A (CsA)-treated group were topically exposed to 20 μL of CsA, twice daily for 14 days. Oral administration of CFW attenuated the PM2.5-induced reduction of tear secretion and corneal epithelial damage. In addition, CFW protected against goblet cell loss in conjunctiva and overexpression of inflammatory factors in the lacrimal gland following topical exposure to PM2.5. Furthermore, CFW markedly prevented PM2.5-induced ganglion cell loss and recovered the thickness of inner plexiform layer. Meanwhile, CFW treatment decreased the levels of total cholesterol and low-density lipoprotein cholesterol in serum induced by PM2.5. Importantly, the efficacy of CFW was superior or similar to that of CsA and lutein. Taken together, oral administration of CFW may have protective effects against PM2.5-induced DED symptoms via stabilization of the tear film and suppression of inflammation. Furthermore, CFW may in part contribute to improving retinal function and lipid metabolism disorder. [ABSTRACT FROM AUTHOR]