Veterinary Ophthalmology Research Articles

PHYSIOLOGICAL FEATURES OF THE IMMUNOLOGICAL STATUS IN PATIENTS WITH ALLERGIC CONJUNCTIVITIS

An important element of clinical ophthalmology is clinical immunology, which considers pathological processes from the point of view of a violation of the immune system. These disorders can play the main etiopathogenetic role or be a factor complicating the pathological process. However, in contrast to human medicine, in veterinary clinical ophthalmology, the issue of the role of the immune system has been insufficiently studied. The problem of allergic diseases is one of the most important for modern practical medicine. Increasing from year to year, the prevalence of various manifestations of allergies is extremely high in different countries of the world.

Presumed neuroprotective therapies prescribed by veterinary ophthalmologists for canine degenerative retinal and optic nerve diseases.

To investigate veterinary ophthalmologists' use of presumed neuroprotective therapies for degenerative retinal and optic nerve diseases in dogs. An online survey was sent to 663 board-certified veterinary ophthalmologists who were Diplomates of the American College of Veterinary Ophthalmologists (ACVO), Asian College of Veterinary Ophthalmologists (AiCVO), Latin American College of Veterinary Ophthalmologists (Colegio Latinoamericano de Oftalmólogos Veterinarios, CLOVE), or European College of Veterinary Ophthalmologists (ECVO). The survey was created using Qualtrics® software and focused on the prescription of presumed neuroprotective treatments for canine glaucoma, sudden acquired retinal degeneration syndrome (SARDS), progressive retinal atrophy (PRA), and retinal detachment (RD). A total of 165 completed surveys were received, representing an overall response rate of 25%, which was comparable across the four specialty colleges. Of all respondents, 140/165 (85%) prescribed some form of presumed neuroprotective therapies at least once in the last five years: 114/165 (69%) for glaucoma, 51/165 (31%) for SARDS, 116/165 (70%) for PRA, and 50/165 (30%) for RD. The three most recommended neuroprotective reagents were the commercial Ocu-GLO™ Vision Supplement for animals, amlodipine, and human eye supplements. Despite lack of published clinical efficacy data, the majority of surveyed board-certified veterinary ophthalmologists previously prescribed a presumed neuroprotective therapy at least once in the last five years in dogs with degenerative retinal and optic nerve diseases.

Veterinary Ophthalmology-Glaucoma Special Issue.

Veterinary Ophthalmology-Glaucoma Special Issue.

تعیین مقدار قابل ارجاع برای اندازهگیری میزان اشک چشم با استفاده از نوار آزمایش اشکی (STT) در اسبچه خزر

BACKGROUND: The Schirmer tear test (STT) is widely used in both human and veterinary ophthalmology. Two types of STTs have been developed: STT I and STT II. OBJECTIVES: The purpose of this research was to determine the reference value for measuring tear production of the Caspian horse by using the Schirmer tear test strip. METHODS: Twenty apparently healthy male and female Caspian horses, aged between 2 and 15 years old and weighing between 192±32 Kg were selected. After physical examination and reviewing the horse's health history and assuring their health, the Schirmer tear test was performed. To produce a higher volume of tears in horses, compared to other animal species, we used the Schirmer tear strip (Schirmer‐ Eickemeyer®, Germany), for 30 seconds instead of one minute in the lower conjunctival sac. In this study, we investigated the effect of age and gender on tear production in the Caspian horse, as well as the comparison between the left and right eyes tear production. RESULTS: The study shows that the results of STT I in the study animals illustrated the mean±SD STT I value was 23.38±3.6 mm/min (range, 15–30 mm/30s). Based on the results of this study, the variants of age and gender had no significant effects on the STT1 results in the Caspian horses. No significant difference was noted between the amount of tear production in the left and right eyes. CONCLUSIONS: Considering the importance of rapid diagnosis of dry eye syndrome and preventing its subsequent disorders such as Keratoconjunctivitis Sicca, the results of this study can be used as the reference value in the future to measure the amount of moisture of caspian horses of the Caspian horse.

Development of and Validity Evidence for a Canine Ocular Model for Training Novice Veterinary Students to Perform a Fundic Examination.

Indirect fundoscopy is challenging for novice learners, as patients are often intolerant of the procedure, impeding development of proficiency. To address this, we developed a canine ocular simulator that we hypothesized would improve student learning compared to live dogs. Six board-certified veterinary ophthalmologists and 19 second-year veterinary students (novices) performed an indirect fundic examination on the model and live dog. Prior to assessment, novices were introduced to the skill with a standardized teaching protocol and practiced (without feedback) with either the model (n = 10) or live dog (n = 9) for 30 minutes. All participants evaluated realism and usefulness of the model using a Likert-type scale. Performance on the live dog and model was evaluated in all participants using time to completion of task, performance of fundic examination using a checklist and global score, identification of objects in the fundus of the model, and evaluation of time spent looking at the fundus of the model using eye tracking. Novices (trained on simulator or live dogs) were compared in fundic examination performance on the live dog and identification of shapes in the model. In general, experts performed the fundic examination faster (p ≤ .0003) and more proficiently than the novices, although there were no differences in eye tracking behavior between groups (p ≥ .06). No differences were detected between training on simulator versus live dog in development of fundoscopy skills in novices (p ≥ .20). These findings suggest that this canine model may be an effective tool to train students to perform fundoscopy.

Reliability of detecting fundus abnormalities associated with systemic hypertension in cats assessed by veterinarians with and without ophthalmology specialty training.

Systemic hypertension (SHT) causes severe target organ damage (TOD) and blood pressure (BP) measurement should be routine in at-risk populations. Fundoscopy is a tool to corroborate acute clinical relevance of high BP results and to decide on immediate therapy. Not every cat with a high BP result can be examined by an ophthalmologist. The study objective was to determine the reliability of fundoscopy in cats with SHT performed by a veterinarian without ophthalmology specialty training. Cats with suspicion of hypertensive TOD or belonging to an at-risk population for SHT with a first measurement of elevated BP >160 mmHg were enrolled. Indirect ophthalmoscopy was performed by a recent graduate veterinarian followed by a veterinary ophthalmologist. Confirmation of SHT was based on two additional sets of systolic BP measurements >160 mmHg by Doppler sphygmomanometry. Thirty-three cats were included. SHT was confirmed in 27 cats. SHT was detected on routine examinations in 12/27 cats; fundoscopic lesions were observed in 9/12 by the non-trained veterinarian and in 11/12 by an ophthalmologist. Nine of 27 cats were neurological patients; fundoscopic lesions were detected in 4/9 by the non-trained veterinarian and in 7/9 by an ophthalmologist. Six of 27 cats were presented for acute blindness; fundus lesions were detected in all six cats by the non-trained veterinarian and ophthalmologist. SHT was not confirmed and fundoscopic lesions were not detected by either examiner in 6/33 cats. Compared with a veterinary ophthalmologist, reliability of detecting fundus abnormalities by the non-trained veterinarian was 72% (13/18) for cats with, and 100% (6/6) for cats without, vision. Fundus examination by a non-specialty trained veterinarian has reasonably high reliability for the detection of ocular TOD. Private practice veterinarians are encouraged to perform an initial fundic examination in suspected hypertensive cats.

Ocular Echobiometry and Resistivity Index of External Ophthalmic Artery in Agoutis (Dasyprocta prymnolopha)

Background: Veterinary Ophthalmology provides complementary information for the diagnosis of ocular pathologies. Studies in wild species are essential. Among the diagnostic techniques in ophthalmology, two-dimensional ultrasonography stands out. The agouti is a rodent belonging to the Dasyproctidae family that has been widely used as an experimental model. For these animals, sight is one of the crucial senses for their survival. The aim of this study was to evaluate the effectiveness of the two-dimensional ocular ultrasound technique to obtain anatomical measurements and the external ophthalmic artery resistivity index, presumably normal in the species Dasyprocta prymnolopha.Materials, Methods & Results: Forty eye bulbs of 20 adult rodents of the species were evaluated by ultrasonography. In these animals, B-mode echobiometry was performed using the transpalpebral approach and the hemodynamic study of the external ophthalmic artery using the color Doppler technique. All examinations were initiated by the left eye bulb and all measurements were performed by only one examiner. The collected data related to echobiometry were analyzed using Bioest 5.0 for Windows. Initially, normality was tested using the Shapiro-Wilk test for each parameter, then the paired t-test was performed, comparing right and left eyes, and a significance level of 5% (P < 0.05) was adopted. Based on the methodology used, the following values were obtained for the right and left eyeballs, respectively: anterior chamber thickness - mean of 1.28 ± 0.3 mm and 1.22 ± 0.1 mm; lens thickness - 8.27 ± 0.9 mm and 8.11 ± 0.9 mm; vitreous chamber thickness - 5.35 ± 0.48 mm and 5.30 ± 0.47 mm and axial length - 12.7 ± 0.9 mm and 13 ± 0.68 mm. The mean external ophthalmic artery resistivity values were 0.4305 ± 0.0390 and 0.4258 ± 0.0387 (right and left eye, respectively), characterizing a low resistance. There was no statistical difference between the right and left eyeballs in any of the studied parameters.Discussion: The use of the convex transducer was feasible, promoting adequate contact with the ocular surface and images of satisfactory quality for obtaining measurements, similar to what was observed in studies evaluating the ocular biometry of primates and dogs. The anterior chamber thickness values in this experiment did not differ statistically between the antimers, as well as observed for dogs. The data obtained for lens thickness did not differ statistically for antimers, like those obtained for other rodent species evaluated with the same methodology. The mean values of vitreous chamber thickness were like those observed in chinchillas but correspond to about half of that obtained for capybaras. In this study, the external ophthalmic artery was characterized in all animals, but obtaining the spectral tracing was difficult due to its fine caliber. In wild animals, and especially in wild rodents, there are few data reporting the resistivity of the ophthalmic artery, and there is a lack of studies, which can be explained by the behavioral characteristics of defense and by the high susceptibility to stress in capture, since the performing the technique requires, as in other procedures, the use of chemical containment.Keywords: Doppler flow, ultrasound, eye, agouti.

Применение препарата Репарин- Хелпер® при лечении язвенно-эрозивных кератитов, возникших на фоне терапии гипертензивной глаукомы

This article summarizes clinical results in treating corneal erosions and ulcers (10 clinical cases) that arose as a complication following prolonged treatment of hypertensive glaucoma. Because glaucoma negatively affects corneal regeneration, healing such corneal defects becomes a complicated and difficult process, frequently accompanied by additional complications and decreased vision quality. For this reason, discovering effective treatments for such corneal defects remains an important goal of veterinary ophthalmologists. The article proposes a modern treatment plan wherein a regenerative drug is used to stimulate the regenerative processes in damaged corneal tissues and to regulate the inflammatory process. Our results show that the regenerative drug successfully accelerated the regeneration of the corneal defect and improved the quality of recovery.

Current ocular microbiome investigations limit reproducibility and reliability: Critical review and opportunities

Enthusiasm for research describing microbial communities using next-generation sequencing (NGS) has outpaced efforts to standardize methodology. Without consistency in the way research is carried out in this field, the comparison of data between studies is near impossible and the utility of results remains limited. This holds true for bacterial microbiome research of the ocular surface, and other sites, in both humans and animals. In addition, the ocular surface remains under-explored when compared to other mucosal sites. Low bacterial biomass samples from the ocular surface lead to further technical challenges. Taken together, two major problems were identified: (1) Normalization of the workflow in studies utilizing NGS to investigate the ocular surface bacteriome is necessary in order to propel the field forward and improve research impact through cross-study comparisons. (2) Current microbiome profiling technology was developed for high bacterial biomass samples (such as feces or soil), posing a challenge for analyses of samples with low bacterial load such as the ocular surface. This article reviews the challenges and limitations currently facing ocular microbiome research and provides recommendations for minimum reporting standards for veterinary ophthalmologists and clinician scientists to limit inter-study variation, improve reproducibility, and ultimately render results from these studies more impactful. The move toward normalization of methodology will expedite and maximize the potential for microbiome research to translate into meaningful discovery and tangible clinical applications.

Bacterial Cross-Contamination in a Veterinary Ophthalmology Setting.

The present study describes the prevalence of bacterial cross-contamination in a veterinary ophthalmology setting, a serious issue that can result in healthcare-associated (or nosocomial) infections among patients and staff. Retrospective (n = 5 patients) and prospective (n = 23 patients) studies evaluated bacterial isolates in companion animals presenting with ulcerative keratitis, sampling the patients' cornea and surrounding examination room, including the environment (exam table, countertop, floor) and ophthalmic equipment (slit lamp, transilluminator, direct ophthalmoscope, indirect headset, tonometer). Results of bacterial culture and antibiotic susceptibility testing were recorded, and degree of genetic relatedness was evaluated in six pairs of isolates (cornea + environment or equipment) using pulse-field gel electrophoresis (PFGE). Overall contamination rate of ophthalmic equipment, environment, and examination rooms (equipment + environment) was 42.9% (15/35 samples), 23.7% (9/38 samples) and 32.9% (24/73 samples), respectively. Methicillin-resistant Staphylococcus pseudintermedius (MRSP), a multi-drug resistant (MDR) pathogen with zoonotic potential, was isolated in 8.2% (6/73) of samples. The patient's cornea was likely the source of cross-contamination in 50% (3/6) of MRSP pairs as evaluated by PFGE; notably, two of the three similar bacterial strains did not have an exact match of their antibiotic susceptibility profiles, highlighting the importance of advanced diagnostics such as PFGE to assess cross-contamination in healthcare facilities. Future work could examine the contamination prevalence of specific equipment or the efficacy of cleaning protocols to mitigate cross-contamination in veterinary practice.

A review of glaucoma surgical therapy.

Glaucoma is a disorder of all species due to a rise of intraocular pressure (IOP) beyond which is compatible with ganglion cell and axon function, often resulting in optic nerve degeneration and irreversible blindness. Glaucoma treatment with surgical intervention aimed at either reducing aqueous production, or increasing or altering aqueous outflow has evolved over preceding decades, but there remains no cure. The present article is intended to provide a concise review of glaucoma surgical therapies in veterinary ophthalmology.

Abstracts: The 51st Annual Scientific Meeting of the American College of Veterinary Ophthalmologists, Virtual Conference, Sept 23-27, 2020.

Abstracts: The 51st Annual Scientific Meeting of the American College of Veterinary Ophthalmologists, Virtual Conference, Sept 23-27, 2020.

Intracanalicular injection of N-acetylcysteine as adjunctive treatment for sialoceles in dogs: 25 cases (2000-2017)

To describe intracanalicular injection of 10% N-acetylcysteine (IINAC) as adjunctive treatment for sialoceles in dogs. 25 client-owned dogs. Hard copy medical records at 2 veterinary ophthalmology practices were searched to identify dogs that underwent IINAC for treatment of sialoceles from January 2000 to December 2017. Signalment, affected salivary gland, clinical signs, duration of signs, other treatments administered, diagnostic tests performed, anesthetic approach, N-acetylcysteine volume administered, complications, follow-up time, and recurrence of sialoceles were recorded. Descriptive statistics were reported. Boxers and mixed-breed dogs were most commonly represented. Subjectively decreased globe retropulsion and conjunctival or periorbital swelling (23/25 [92%] dogs each) were the most common clinical signs, with no vision deficits in any patient. The zygomatic gland was mainly affected (23/25 [92%] dogs), followed by parotid and mandibular glands (1 [4%] dog each). The condition was unilateral in 22 (88%) dogs. Ultrasonography (19/25 [76%] dogs), MRI (14 [56%]), fine-needle aspiration (20 [80%]), and biopsy (4 [16%]) were performed; however, the condition was deemed idiopathic in 22 (88%) dogs. Most IINACs were performed with local anesthesia (median volume, 5 mL/gland; range, 1.5 to 9 mL). No complications were identified. Other treatments included antimicrobials and anti-inflammatories. Mean follow-up time was 18.8 months. All recurrences (5/23 [22%] dogs) were controlled with medical management. Results suggested noninvasive IINAC may be a useful adjunctive treatment for sialoceles in dogs. The procedure was easily and safely performed with local anesthesia (or general anesthesia with concurrent diagnostic imaging) in these dogs.

A description of blend electrolysis for treatment of canine distichiasis: 78 cases (2012–2017)

ObjectiveTo describe a population of dogs treated with blend electrolysis for distichiasis at The Royal Veterinary College and report the complications seen.MethodsIn part 1, records were reviewed from 2012 to...

Prophylactic anti-glaucoma therapy in dogs with primary glaucoma: A practitioner survey of current medical protocols.

To examine the use of prophylactic anti-glaucoma medications in the normotensive fellow eye in dogs with unilateral overt primary glaucoma by veterinary ophthalmology clinicians. A survey of veterinary ophthalmology clinicians was distributed over two international list serves servicing veterinary ophthalmologists, trainees, and individuals whose practice consisted primarily of ophthalmic patients. The survey was developed following analysis of historical and currently available medical options for control of intraocular pressure and for neuroprotection. Responses from 199 veterinary ophthalmology clinicians were evaluated. While a large variety of topical anti-hypertensive drugs and protocols were used, the most commonly used medications were aqueous humor production suppressors such as dorzolamide 2.0% ophthalmic solution, timolol 0.5% ophthalmic solution, and a combination product containing both drugs. Latanoprost 0.005% ophthalmic solution was used infrequently for prophylaxis by comparison. The majority of respondents do not use concurrent anti-inflammatory medications (61.22%), although a sizeable minority used prednisolone acetate, dexamethasone, or ketorolac as prophylactic treatment. Systemically administered ocular anti-hypertensive agents were rarely used. Only 40% of respondents used neuroprotectant agents; the most commonly prescribed were the calcium channel blocker amlodipine and the nutraceutical Ocu-Glo™. Recommended intervals between re-examination by the clinician ranged from one month to one year, with most re-evaluations occurring every 3 to 6months. The majority of respondents recommended more frequent assessments of IOP at intervals between once monthly and once every 3months. Data analysis of medical therapy for the normotensive fellow eye of dogs previously diagnosed with primary glaucoma suggests that there is a great need for well-designed, prospective, controlled, multi-center studies to determine which protocols have the greatest efficacy in delaying an overt attack in the previously normotensive eye in dogs with a genetic predisposition to glaucoma. Prospective studies utilizing a carbonic anhydrase inhibitor such as dorzolamide and a prostaglandin analogue such as latanoprost would be reasonable as these two drugs are widely used in the treatment of overt glaucoma and would allow for an exploration of the impact of different mechanisms of action of lowering IOP on the pathophysiology of primary glaucoma.

Comparison between the Effect of Hyaluronic Acid and Mesenchymal Stem Cell Therapy on Cornea of Adult Albino Rats after Exposure to Alkali Burn (Light and Electron Microscopic Study)

Background: Corneal epithelial injuries are common in both physician and veterinary ophthalmology that often causes extensive damage and results in permanent visual impairment. Aim of work: to evaluate the beneficial effect of hyaluronic acid and MSCs in treatment of experimental alkali corneal burn. Subjects and methods: thirty adult albino rats of both sexes. Ten rats were used to harvest BM-MSCs while the others were divided into four groups. Group I was the control group. Group II with unilateral alkali-burnt cornea these rats were sacrificed after 1 day and the other sacrificed after 2 weeks. Group III were rats with unilateral hyaluronic acid-treated alkali-burnt corneas for 2 weeks. Group IV were rats with MSCs treated alkali-burnt corneas. Immune histochemical staining for CD44 and vimentin was performed. The corneas were examined using light microscopic, transmission electron microscopic and morphometric studies. Results: Corneal alkali burn resulted in desquamation of corneal epithelium in group II. The epithelial cell layers had vacuolated cytoplasm with pyknotic nuclei. The stroma contained irregularly arranged collagen fibers with wide spacing and congested blood vessels with cellular infiltration. Groups III and IV showed improvement of the histological and electron microscopic changes described in group II. Conclusions: The use of MSCs in the acute stage of corneal chemical trauma was associated with faster recovery of the wounded cornea when compared with the effect of hyaluronic acid sodium salt.

Role Of Ultrasonography In The Diagnosis And Management Of Endophthalmitis In Cats

Endophthalmitis is one of the most devastating diagnoses in veterinary and human ophthalmology. Ocular ultrasound is an effective and non-invasive technique used for evaluating the structures of the eye and the surrounding tissues, especially when the development of ocular opacities in conditions such as corneal disease, uveitis, cataracts or trauma prevent or limit the use of ophthalmoscopy and slit-lamp biomicroscopy. The present study aimed to evaluate the ultrasonographic characteristics of endophthalmitis in cats and to assess the usefulness of ultrasonography in the selection of treatment methods in such cases. Sixty cats (90 eyes) of different breeds were presented with bilateral (30 cats) and unilateral (30 cats; OD=10, OS=20) endophthalmitis. The mean age ± SEM at the initial presentation was 13.46±1.69 months (range, 2 - 72 months). After a thorough ophthalmic examination, the ultrasonographic evaluation using a high frequency (7.5-10 MHz) micro-convex probe was conducted to evaluate the concurrent ocular abnormalities in the anterior and posterior eye segments. After completing the ultrasonographic examination, the treatment protocol was applied. It was concluded that ocular ultrasonographic evaluation was found suitable in the diagnosis of endophthalmitis in cats and for the selection of the treatment protocol

Surveying veterinary ophthalmologists to assess the advice given to owners of pets with irreversible blindness

BackgroundThe primary purpose of this survey was to determine how veterinary ophthalmologists manage cases of irreversible blindness and to report the most common causes of blindness.MethodsRespondents completed a questionnaire sent...

Diagnosis and treatment of glaucoma in client-owned rabbits (Oryctolagus cuniculus): 16 eyes from 11 rabbits (2008–2019)

BackgroundAlthough rabbits are commonly used as laboratory models for human glaucoma, management of this disease in pet rabbits has received little attention in the current literature. Spontaneous congenital glaucoma was initially described in New Zealand Whites as an autosomal recessive trait manifesting early in life. Glaucoma may also develop secondary to cataracts, uveitis, or other ocular pathologies. Findings associated with glaucoma in rabbits include elevated intraocular pressure (IOP), corneal edema, loss of vision, optic nerve head cupping, and progressive buphthalmia. Topical medications, intravitreal gentamicin injections, and various surgical techniques have been used to manage glaucoma in rabbits. This case series details the presentation, diagnosis, treatment, and clinical progression of glaucoma in rabbits at Cummings Veterinary Medical Center at Tufts University and VCA South Shore (Weymouth) Animal Hospital from 2008-2019. MethodsThe records of Cummings Veterinary Medical Center at Tufts University and VCA South Shore (Weymouth) Animal Hospital were retrospectively reviewed to identify records of rabbits diagnosed with glaucoma by a board-certified veterinary ophthalmologist or ophthalmology resident between 2008-2019. ResultsGlaucoma was diagnosed in 16 eyes from 11 rabbits. Median IOP at diagnosis was 39 mmHg (26-55 mmHg) with various clinical signs at presentation including vision loss (11 rabbits, 16 eyes), buphthalmia (8 rabbits, 11 eyes), corneal edema (4 rabbits, 5 eyes), and optic nerve head cupping (5 rabbits, 6 eyes). Other ocular examination findings included cataracts (5 rabbits, 8 eyes) and uveitis (4 rabbits, 8 eyes). Two rabbits were seropositive for Encephalitozoon cuniculi. All eyes were initially treated with topical medications, with 10 eyes from 7 rabbits refractory to initial medical management. Two rabbits (3 eyes) showed progressive reduction in IOPs with long-term continuing topical therapy. Two rabbits (2 eyes) underwent unilateral enucleation and 3 rabbits (5 eyes) received intravitreal gentamicin injections. ConclusionsEtiology of glaucoma in rabbits is likely more varied than previously thought, as many of the cases described were not consistent with primary congenital glaucoma. Topical treatments were effective in many rabbits. In those refractory to medical management, enucleation or intravitreal gentamicin injection were successful in decreasing IOP as second-line therapy when performed.

Characterising keratometry in different dog breeds using an automatic handheld keratometer.

BackgroundKeratometry is clinically important and is routinely performed as part of human ophthalmic examination. In veterinary ophthalmology, little is known about keratometry in dogs, and its practical application has been limited. The present study aimed to describe keratometry in some dog breeds popular in Japan using a handheld keratometer.MethodsClient-owned dogs of various signalment were enrolled prospectively in the keratometry examination. Interbreed variations in mean corneal curvatures (R1R2avg) and corneal astigmatism (Δ(R1−R2)) were evaluated statistically with respect to their bodyweight based on the data which fulfilled the predetermined inclusion criteria. P<0.05 was considered statistically significant.ResultsOn examination of 237 dogs from 16 different breeds, R1R2avg (mean±sd) ranged from 7.54±0.30 mm in Pomeranians to 9.28±0.19 mm in golden retrievers. Δ(R1−R2) (mean±sd) ranged from 0.22±0.11 mm in miniature schnauzers to 0.57±0.30 mm in French bulldogs.ConclusionThe present study successfully described keratometry in 16 dog breeds. The study revealed considerable interbreed variations in both R1R2avg and Δ(R1−R2), which did not necessarily correlate with bodyweight. These results are useful both clinically in fitting contact lenses in the management of corneal diseases and non-clinically in optometric studies in dogs.