Optical coherence tomographic features of feline acute corneal hydrops: A case report.

OBJECTIVE: The objective of the study was to describe the optical coherence tomographic features of a cat with acute corneal hydrops. ANIMAL STUDIED: A 4-year-old castrated male domestic shorthaired showing conjunctival redness, ocular discharge, and intermittent squinting of both eyes with asymmetrical disease onset. METHODS: Complete ophthalmic examination and optical coherence tomography were performed. RESULTS: On slit-lamp biomicroscopic examination, severe intrastromal fluid pockets with profound bullae were observed in the dorsomedial region in both eyes. A diagnosis of feline acute corneal hydrops was made in both eyes. Optical coherence tomography revealed profound stromal lamellar separation representing heterogeneous reflective areas, and fluid pockets and bullae of variable size were concomitant to Descemet's membrane detachment demonstrated by a well-defined homogeneous hyporeflective area. Upon reevaluation 30 days during healing process for both eyes, the thickened epithelia and the thinning pan-stromal areas were identified as homogeneously hyper-reflective epithelia and as heterogeneous hyper-reflectivity, respectively. A thickened posterior corneal surface was shown as heterogeneous with patchy hyper-reflectivity. Additionally, Descemet's membrane detachment in the initial presentation had two distinct forms suspicious of Descemet's membrane rupture in each eye: a break with rolled ends and a break with flat ends. CONCLUSION: To the author's knowledge, this study represents the first documentation of in vivo detection of Descemet's membrane detachment and presumed rupture in a cat experiencing acute corneal hydrops. These observations strongly indicate that Descemet's membrane detachment/rupture acts as a most likely risk factor in the onset of acute corneal hydrops in cats.

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.

Tear clearance rate in dogs: Measurement using anterior segment optical coherence tomography.

OBJECTIVE: The tear clearance rate (TCR), determined using anterior segment optical coherence tomography (AS-OCT) images, and its correlation with ocular surface parameters, including blink rate, Schirmer tear test-1 (STT-1) and tear film breakup time (TFBUT), were evaluated. ANIMALS STUDIED: Left eyes of 20 client-owned dogs with no ocular disease symptoms. PROCEDURES: The tear meniscus height (TMH) was evaluated using AS-OCT images before the instillation of 5 µL saline (TMHbase ), immediately post-instillation (TMH0 ), 30-s post-instillation (TMH0.5 ) and at 1 min intervals for 5 min post-instillation (TMH1 , TMH2 , TMH3 , TMH4 and TMH5 ). The TCR was calculated using the formula [(TMH0  - TMH0.5 )/TMH0 ]×100 (%). The eyes were classified into two groups with the median: 'High TMHbase ' (n = 10) and 'Low TMHbase ' (n = 10). Eyes with STT-1 values ≥15 mm/min and TFBUT ≥ 12 s were assigned to the 'Satisfied' subgroup, whereas eyes not satisfying these criteria were assigned to the 'Not satisfied' subgroup. RESULTS: TMH0 was higher than TMH0.5 (p = 0.02), wherein TMH0.5 to TMH5 did not differ significantly. The TCR and blink rate were negatively correlated (p = 0.02). The 'Not satisfied' subgroup in the low TMHbase group had a lower TCR (p = 0.02) and higher blink rate (p = 0.04) than the 'Satisfied' subgroup. CONCLUSIONS: TCR can be evaluated using AS-OCT in dogs. Eyes with a lower TCR blink more frequently. TMH merits studying to understand ocular surface health.

Treatment of immune-mediated keratitis (IMMK) in dogs with immunosuppressants observed with spectral domain optical coherence tomography (SD-OCT).

Two dogs presented with bilateral pattern-forming corneal opacity. Treatment with topical immunosuppressants was initiated after a complete ophthalmic examination. The response to treatment was assessed by analyzing serial images using slit-lamp biomicroscopy and spectral domain optical coherence tomography (SD-OCT). Both dogs responded to topical immunosuppressants; however, the lesions recurred once the treatment was abated or withdrawn. The most effective immunosuppressant in both dogs was 0.03% tacrolimus ointment. Early and continuous treatment with topical immunosuppressants may be necessary to improve corneal clarity and prevent scarring. SD-OCT could provide useful structural information regarding presumed immune-mediated keratitis and aid in monitoring treatment response.

Inter-device agreement between spectral domain optical coherence tomography, ultrasound biomicroscopy, and gonioscopy in evaluating the iridocorneal angle in normotensive dogs.

BACKGROUND: There has not been a thoroughly reported study of the comparison between spectral domain-optical coherence tomography (SD-OCT) with both ultrasound biomicroscopy (UBM) and gonioscopy on the evaluation of the iridocorneal angle (ICA) in dogs. OBJECTIVES: To investigate the diagnostic value of SD-OCT for the early detection of narrowing ICA by comparing and assessing inter-device agreement in anterior chamber angle (ACA) measurements obtained by SD-OCT and UBM, and ICA evaluations by gonioscopy. METHODS: A total of 28 eyes from 28 client-owned dogs with normal intraocular pressure were included for examination. The ACA and angle opening distance (AOD) were measured from the SD-OCT and UBM images, and gonioscopy images were analyzed using the ICA grade and ZibWest angle index. RESULTS: The mean ACA and AOD for SD-OCT were 28.31° ± 5.37° and 658.42 ± 219.90 µm, and for UBM, 28.34° ± 5.82° and 859.29 ± 221.80 µm, respectively. The mean difference in ACA between the average values of SD-OCT and UBM measurements was 0.03° with a 95% limit of agreement (LoA) span of 16.2°, indicating positive agreement; that in AOD was 200.85 µm with a 95% LoA span of 1,110.95 µm, indicating poor agreement. The Pearson correlation coefficient of the ACA of SD-OCT and ZibWest indices of gonioscopy was 0.624, indicating strong agreement; that of UBM and gonioscopy was 0.43, indicating moderate agreement. CONCLUSIONS: SD-OCT is well tolerated by canine patients due to its non-contact method and might be an alternative option for early screening of ICA narrowing in clinical settings.

Bilateral corneal dermoids associated with bilateral choroido-scleral colobomas in a cat: retinographic and optical coherence tomography study with surgical outcome and follow-up.

PURPOSE: To report a case of feline bilateral corneal dermoids, associated with unilateral iris coloboma and bilateral choroido-scleral colobomas in the same dorsolateral position, to describe retinographic and optical coherence tomography (OCT) characteristics, surgical outcome, and follow-up. ANIMAL STUDIED: A 9-month-old domestic shorthaired cat in which a full ophthalmoscopic examination was performed for evaluation of dermoids resulting in a diagnosis of associated iris coloboma in one eye and posterior colobomas in both eyes. PROCEDURES: Retinographies and OCT were performed under anesthesia to characterize the lesions of both fundi and allow surgical excision of the corneal dermoids. RESULTS: Ophthalmoscopy and retinographies revealed oval lesions in the dorsolateral fundi of both eyes. The lesions precisely mirrored their respective dermoids' (10-11 h OD and 1-2 h OS) clock positions, lacked a tapetum lucidum and choroidal vessels, and featured thin retinal vessels plunging to a posterior plane of the fundus. OCT crossline scans demonstrated preservation of retinal thickness and morphological layering in the fundic colobomas leading to the conclusion that the colobomas were purely choroido-scleral. The outcome of the surgical excision of the dermoids was satisfactory without hair recurrence and with acceptable corneal clarity making it possible to visualize the unilateral associated iris coloboma. Follow-ups did not reveal any fundic evolution nor retinal detachment. CONCLUSIONS: Retinographies and OCT made possible the characterization of choroido-scleral colobomas associated with corneal dermoids in this first reported case in a cat. We hypothesize that the recently described superior ocular sulcus might be the embryological link between these anomalies.

A case of Candida albicans-induced fungal keratitis in a Chihuahua dog - with a focus on optical coherence tomographic features.

A 4-year-old Chihuahua dog was referred for bilateral corneal ulcers. Slightly raised white fluorescein-positive plaque-like corneal lesions in both eyes appeared as intense hyperreflective areas with posterior shadowing on optical coherence tomography (OCT). Based on corneal cytology and culture, Candida albicans-induced fungal keratitis was diagnosed. Despite treatment, on OCT, endothelial plaques, increased stromal infiltration thickness, vertical shapes of the ulcer edge, and necrotic stromal space were judged to be aggravation of the disease, and surgery was performed. Conjunctival grafting surgery with topical 1% voriconazole effectively resolved fungal keratitis. OCT can provide detailed and objective information related to the disease prognosis.

Preliminary characterization of a novel form of progressive retinal atrophy in the German Spitz dog associated with a frameshift mutation in GUCY2D.

OBJECTIVE: To describe the clinical, preliminary electroretinographic and optical coherence tomography features of a newly identified form of progressive retinal atrophy (PRA) in German Spitzes, and identify the causal gene mutation. ANIMALS: Thirty-three client-owned German Spitz dogs were included. PROCEDURES: All animals underwent a full ophthalmic examination, including vision testing. In addition, fundus photography, ERG, and OCT were performed. A DNA-marker-based association analysis was performed to screen potential candidate genes and the whole genomes of four animals were sequenced. RESULTS: Initial fundus changes were pale papilla and mild vascular attenuation. Oscillatory nystagmus was noted in 14 of 16 clinically affected puppies. Vision was impaired under both scotopic and photopic conditions. Rod-mediated ERGs were unrecordable in all affected dogs tested, reduced cone-mediated responses were present in one animal at 3 months of age and unrecordable in the other affected animals tested. Multiple small retinal bullae were observed in three clinically affected animals (two with confirmed genetic diagnosis). OCT showed that despite loss of function, retinal structure was initially well-preserved, although a slight retinal thinning developed in older animals with the ventral retina being more severely affected. Pedigree analysis supported an autosomal recessive inheritance. A mutation was identified in GUCY2D, which segregated with the disease (NM_001003207.1:c.1598_1599insT; p.(Ser534GlufsTer20)). Human subjects with GUCY2D mutations typically show an initial disconnect between loss of function and loss of structure, a feature recapitulated in the affected dogs in this study. CONCLUSION: We identified early-onset PRA in the German Spitz associated with a frameshift mutation in GUCY2D.

Optical Coherence Tomography: A Review of Current Applications in Veterinary Ophthalmology.

Normative standards for healthy animal structures have been established by optical coherence tomography (OCT). OCT has been used in animal studies to characterize more precisely ocular lesions, identify the origin of the affected layer, and eventually provide a curative treatment. To acquire a high image resolution, several challenges must be overcome when performing an OCT scan on animals. Sedation or general anesthesia is usually necessary in OCT image acquisition to alleviate motion during image acquisition. Mydriasis, eye position and movements, head position, and corneal hydration must also be managed during the OCT analysis.

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.

Two is not necessarily better than one: A double lens in a pre-metamorphic adult axolotl (Ambystoma mexicanum).

An 8-year-old female pre-metamorphic axolotl (Ambystoma mexicanum) was examined for a suspected anterior lens luxation. Slit-lamp biomicroscopy revealed two lens-like structures in the anterior chamber of the right eye (OD), each with cataractous change. Ultrasound biomicroscopy and optical coherence tomography (OCT) were performed without sedation, and revealed small lenticular structures each with distinct nuclei and cortices. Although a distinct connection of the two lenticular structures could not be definitively ruled out, the structures appeared separate. Each of the lenticular structures was closely associated with its respective iris leaflet. This report demonstrates application of advanced imaging for diagnostic use in axolotl ophthalmology, showing that imaging of the lens can be performed without sedation, topical anesthetic, nor contact gel with high diagnostic quality. Although two distinct lenses were diagnosed with no historical evidence of trauma, the small sizes of each lenticular structure, with no detectable connection between them, are suggestive of a possible regenerative abnormality. This report opens discussion for the regenerative capabilities of the pre-metamorphic adult axolotl and possible implementations of their use in regenerative medicine research for the development of future therapies.

Optical coherence tomography for surgical margin evaluation of excised canine cutaneous and subcutaneous tumours.

Currently, intraoperative tumour margin imaging is not routinely utilized in veterinary medicine. Optical coherence tomography (OCT) allows for real-time assessment of tissue morphology of 1-2 mm depth. The aims of this study were (1) to compare the histologic and OCT features of excised canine skin and subcutaneous specimens, and (2) to determine the diagnostic accuracy of OCT for surgical margin evaluation. The authors hypothesized that OCT imaging would correlate well with histopathology and that OCT would be sensitive for detection of incomplete margins. Eighty dogs were prospectively enrolled. Tumours were excised, and the surgical margins were imaged using a spectral domain OCT system. The tumour type and completeness of excision were determined by histopathology. Nine blinded observers received training in OCT image interpretation and were then given a set of OCT images and videos. The observers assigned each image/video a grade from 1 (no tumour) to 4 (tumour) and the results were compared to histopathology. The overall median sensitivity and specificity of OCT imaging for detection of incomplete margins were 86.7% and 84.6%, respectively. A potential limitation is that observers had varied experience with OCT image interpretation, ranging from no prior experience to participating in a previous OCT project. OCT is sensitive for detection of incomplete margins and could be a promising real-time surgical margin imaging modality. Further study is needed to evaluate intraoperative applications of OCT and its impact on tumour recurrence and long-term outcome.

An unusual inherited electroretinogram feature with an exaggerated negative component in dogs.

OBJECTIVES: To assess an inherited abnormal negative response electroretinogram (NRE) that originated in a family of Papillon dogs. ANIMALS STUDIED: Thirty-eight dogs (Papillons, or Papillon cross Beagles or Beagles). PROCEDURES: Dogs underwent routine ophthalmic examination and a detailed dark-adapted, light-adapted and On-Off electroretinographic study. Vision was assessed using a four-choice exit device. Spectral-domain optical coherence tomography (SD-OCT) was performed on a subset of dogs. Two affected males were outcrossed to investigate the mode of inheritance of the phenotype. RESULTS: The affected dogs had an increased underlying negative component to the ERG. This was most pronounced in the light-adapted ERG, resulting in a reduced b-wave and an exaggerated photopic negative response (PhNR). Changes were more pronounced with stronger flashes. Similarly, the On-response of the On-Off ERG had a reduced b-wave and a large post-b-wave negative component. The dark-adapted ERG had a significant increase in the scotopic threshold response (STR) and a significant reduction in the b:a-wave ratio. Significant changes could be detected at 2 months of age but became more pronounced with age. Vision testing using a four-choice device showed affected dogs had reduced visual performance under the brightest light condition. There was no evidence of a degenerative process in the affected dogs up to 8.5 years of age. Test breeding results suggested the NRE phenotype had an autosomal dominant mode of inheritance. CONCLUSIONS: We describe an inherited ERG phenotype in Papillon dogs characterized by an underlying negative component affecting both dark- and light-adapted ERG responses.

The use of optical coherence tomography for skin evaluation in healthy rats.

BACKGROUND: Noninvasive diagnostic techniques allow for morphological and morphometric in vivo evaluation of the skin. Optical coherence tomography (OCT) is a method that allows visualization of dermal structures up to several 100 µm with a resolution of 3-7.5 µm. OBJECTIVES: The aim of the study was the morphological and morphometric assessment of rats' skin using SD-OCT. ANIMALS: Fifteen male Wistar rats, aged 3 and 8 months, weighing 350-450 g. MATERIALS AND METHODS: The skin of the plantar metatarsal area of the right pelvic limb was assessed. The measurements were performed using Spectral Domain Optical Coherence Tomography (SD-OCT) scans and histological images. RESULTS: Spectral Domain Optical Coherence Tomography could determine the boundary between the epidermis and the dermis. Apart from the stratum corneum (SC), it did not allow for the differentiation of the individual epidermal layers. In the SD-OCT and in the histological examination, the mean thicknesses of the layers (µm ± SD) were (respectively): SC 33.053 ± µm(SD 5.85, 29.675 ± 5.54; epidermis 88.2 ± 7.97, 65.126 ± 13.23; dermis 259.86 ± 18.29, 166.05 ± 31.88 µm. There was a correlation between the total epidermal SD-OCT and histological measurements (r = 0.43, p = 0.05). Bland-Altman plots revealed a bias of -19.18 (95% confidence interval) -39.21 to 0.84 µm) in the case of live epidermis (stratum granulosum, stratum spinous, stratum basale). CONCLUSIONS AND CLINICAL RELEVANCE: Spectral Domain Optical Coherence Tomography can be used to evaluate rat epidermis and dermis. The method enables the differentiation of the SC, as well as the epidermis and the dermis. SD-OCT and histological thickness dimensions of the epidermis and skin differ.

Contexte - Les techniques de diagnostic non invasives permettent une évaluation morphologique et morphométrique in vivo de la peau. La tomographie par cohérence optique (OCT) est une méthode qui permet de visualiser les structures dermiques jusqu'à plusieurs centaines de micromètres avec une résolution de 3 à 7,5 µm. Objectifs - Le but de l'étude était l'évaluation morphologique et morphométrique de la peau des rats par SD-OCT. Animaux - Quinze rats Wistar mâles, âgés de 3 et 8 mois, pesant 350-450 g. Matériels et méthodes - La peau de la zone métatarsienne plantaire du membre pelvien droit a été évaluée. Les mesures ont été réalisées à l'aide de scaners SD-OCT (Spectral Domain Optical Coherence Tomography) et d'images histologiques Résultats - Le SD-OCT a pu déterminer la frontière entre l'épiderme et le derme. En dehors de la couche cornée (SC), il n'a pas permis la différenciation des couches épidermiques individuelles. Au SD-OCT et à l'examen histologique, les épaisseurs moyennes des couches (µm ± SD) étaient (respectivement) : SC 33,053 ± µm (SD 5,85, 29,675 ± 5,54 ; épiderme 88,2 ± 7,97, 65,126 ± 13,23 ; derme 259,86 ± 18,29, 166,05 ± 31,88 µm). Il y avait une corrélation entre le SD-OCT épidermique total et les mesures histologiques (r = 0,43, P = 0,05) Les tracés de Bland-Altman ont révélé un biais de -19,18 (intervalle de confiance à 95 %) -39,21 à 0,84 µm) dans le cas d'épiderme vivant (stratum granulosum, stratum spinous, stratum basale). Conclusions et pertinence clinique - Le SD-OCT peut être utilisé pour évaluer l'épiderme et le derme de rat. La méthode permet de différencier le SC, ainsi que l'épiderme et le derme. Le SD-OCT et les dimensions d'épaisseur histologiques de l'épiderme et de la peau diffèrent.

Introducción - las técnicas de diagnóstico no invasivas permiten la evaluación morfológica y morfométrica in vivo de la piel. La tomografía de coherencia óptica (OCT) es un método que permite la visualización de estructuras dérmicas de hasta varios cientos de micrómetros con una resolución de 3 a 7,5 µm. Objetivos - El objetivo del estudio fue la evaluación morfológica y morfométrica de la piel de ratas mediante SD-OCT. Animales - Quince ratas Wistar macho, de 3 y 8 meses de edad, con un peso de 350 a 450 g. Materiales y métodos - Se evaluó la piel de la zona metatarsiana plantar del miembro pélvico derecho. Las mediciones se realizaron utilizando escaneos SD-OCT (Tomografía de Coherencia Óptica de Dominio Espectral) e imágenes histológicas. Resultados - SD-OCT pudo determinar el límite entre la epidermis y la dermis. Aparte del estrato córneo (SC), no permitía la diferenciación de las capas epidérmicas individuales. En la SD-OCT y en el examen histológico, los espesores medios de las capas (µm ± SD) fueron (respectivamente): SC 33.053 ± µm (SD 5.85, 29.675 ± 5.54; epidermis 88.2 ± 7.97, 65.126 ± 13.23; dermis 259.86 ± 18,29, 166,05 ± 31,88 µm. Hubo una correlación entre el SD-OCT epidérmico total y las mediciones histológicas (r = 0,43, P = 0,05). Las gráficas de Bland-Altman revelaron un sesgo de -19,18 (intervalo de confianza del 95 %) -39,21 a 0,84 µm) en el caso de epidermis viva (estrato granuloso, estrato espinoso, estrato basal). Conclusiones y relevancia clínica- SD-OCT se puede utilizar para evaluar la epidermis y la dermis de rata. El método permite diferenciar el SC, así como la epidermis y la dermis. Las dimensiones de grosor de la epidermis y la piel difieren entre SD-OCT y la histología.

Contexto - Técnicas diagnósticas não invasivas permitem a avaliação morfológica e morfométrica in vivo da pele. A tomografia de coerência óptica (OCT) é um método que possibilita a visualização de estruturas dérmicas de até centenas de micrômetros com uma resolução de 3-7,5 µm. Objetivos - O objetivo do estudo foi a avaliação morfométrica e morfológica da pele de ratos utilizando SD-OCT. Animais - Quinze ratos Wistar machos, de três a oito meses de idade, pesando de 350 a 450 g. Materiais e métodos - A pele da região metatársica plantar do membro pélvico direito foi avaliada. As mensurações foram realizadas utilizando o SD-OCT (Spectral Domain Optical Coherence Tomography) e imagens histológicas. Resultados - A SD-OCT foi capaz de determinar o limite entre derme e epiderme. A exceção do estrato córneo (SC), não foi possível a diferenciação das camadas da epiderme individualmente. Na SD-OCT e na avaliação histológica, as espessuras médias das camadas fora, (µm ± DP), respectivamente: SC 33,053 ± 5,85; 29,675 ± 5,54; epiderme 88,2 ± 7,97; 65,126 ± 13,23; derme 259,86 ± 18,29; 166,05 ± 31,88 µm. Houve correlação entre SD-OCT e avaliação histológica nas mensurações da epiderme total (r = 0,43, P = 0,05). Os gráficos de Bland-Altman revelaram um viés de -19,8% (95% de intervalo de confiança) - 39,21 a 0,84 µm) no caso da epiderme viva (estrato espinhoso, estrato granuloso e estrato basal). Conclusões e relevância clínica - SD-OCT pode ser utilizada para avaliar a derme e a epiderme de ratos. Este método permite a diferenciação do SC, bem como da derme e epiderme. Pode haver discrepância na espessura da epiderme e da pele na SD-OCT e análise histológica.

Outer retinal thickness and visibility of the choriocapillaris in four distinct retinal regions imaged with spectral domain optical coherence tomography in dogs and cats.

PURPOSE: To evaluate the outer retinal band thickness and choriocapillaris (CC) visibility in four distinct retinal regions in dogs and cats imaged with spectral domain optical coherence tomography (SD-OCT). To attempt delineation of a fovea-like region in canine and feline SD-OCT scans, aided by the identification of outer retinal thickness differences between retinal regions. METHODS: Spectralis® HRA + OCT SD-OCT scans from healthy, anesthetized dogs (n = 10) and cats (n = 12) were analyzed. Scanlines on which the CC was identifiable were counted and CC visibility was scored. Outer nuclear layer (ONL) thickness and the distances from external limiting membrane (ELM) to retinal pigment epithelium/Bruch's membrane complex (RPE/BM) and ELM to CC were measured in the area centralis (AC), a visually identified fovea-like region, and in regions superior and inferior to the optic nerve head (ONH). Measurements were analyzed using a multilevel regression. RESULTS: The CC was visible in over 90% of scanlines from dogs and cats. The ONL was consistently thinnest in the fovea-like region. The outer retina (ELM-RPE and ELM-CC) was thickest within the AC compared with superior and inferior to the ONH in dogs and cats (p < .001 for all comparisons). CONCLUSIONS: The CC appears a valid, albeit less than ideal outer retinal boundary marker in tapetal species. The AC can be objectively differentiated from the surrounding retina on SD-OCT images of dogs and cats; a fovea-like region was identified in dogs and its presence was suggested in cats. These findings allow targeted imaging and image evaluation of these regions of retinal specialization.

Multimodal ocular imaging of known and novel corneal stromal disorders in dogs.

BACKGROUND: Imaging features obtained with Fourier-domain optical coherence tomography (FD-OCT) and in vivo confocal microscopy (IVCM) for corneal stromal disorders have been sparsely reported in dogs. This case report is a compilation of imaging features for three cases of different stromal disorders of the canine cornea which have not yet been reported elsewhere. CASE PRESENTATION: Lipid deposition in case 1 appeared as needle-shaped hyperreflective lines along the collagen lamellae, which correlated histologically with lipid clefts. In case 2, glycosaminoglycan accumulation by mucopolysaccharidosis type 1 caused diffuse stromal hyperreflectivity and depletion of keratocytes on IVCM and was associated with secondary corneal degeneration presumed to be calcium deposition. In case 3, posterior corneal stromal opacities in the absence of ocular inflammation were identified. Hyperreflective particles were scattered in the middle and posterior corneal stroma on FD-OCT. With IVCM, hyperreflective deposits were identified within keratocytes and the number of enlarged keratocytes containing hyperreflective deposits increased towards the posterior stroma. The bilateral, non-inflammatory nature and unique appearance with IVCM is most consistent with a posterior stromal dystrophy reminiscent of pre-Descemet corneal dystrophy described in humans. CONCLUSIONS: In vivo multimodal corneal imaging facilitated instantaneous microstructural analysis and may be valuable in the differential diagnosis of corneal stromal disorders in veterinary clinical practice. The non-specific nature of imaging findings occurs in some conditions such as mucopolysaccharidosis, thus in vivo corneal imaging should be complemented with other gold standard methods of definitive diagnosis.

Non-invasive optical coherence tomography angiography: A comparison with fluorescein and indocyanine green angiography in normal adult dogs and cats.

PURPOSE: While the retinal vasculature can be assessed by simple funduscopy, a more detailed assessment can be performed by conventional angiography using dyes such as fluorescein or indocyanine green. The development of optical coherence tomography angiography (OCT-A) allows a non-invasive detailed examination of posterior segment vasculature. The purpose of this prospective study was to compare imaging of posterior segment vasculature in normal dogs and cats using OCT-A, fluorescein angiography (FA), and indocyanine green angiography (ICGA). METHODS: Eight adult funduscopically normal dogs and 13 funduscopically normal cats were included in the study. Retinal vasculature was assessed by OCT-A followed by ICGA then FA. Regular fundus imaging was also performed. RESULTS: High-resolution images of the different vascular layers within the retina and choroid could be acquired using OCT-A in both dogs and cats. The technique provided more detail than obtained with FA/ICGA. However, artifacts/errors can occur during OCT-A image acquisition/analysis/interpretation and must be considered. Furthermore, OCT-A only allows for a limited field of view compared to FA/ICGA. CONCLUSIONS: Optical coherence tomography angiography is a new non-invasive posterior segment imaging technique that is complementary to traditional dye-based angiographic techniques. Detailed imaging of the dog and cat posterior segment can be achieved under general anesthesia. OCT-A provides additional detail of the vasculature and can clearly demonstrate the anatomical depth of the imaged vessels. There are, however, some limitations to this new technique that may be overcome by future technological advances.

Comparison of the qualitative and quantitative optical coherence tomographic features between sudden acquired retinal degeneration syndrome and normal eyes in dogs.

OBJECTIVE: To quantitatively and qualitatively characterize the retinal optical coherence tomographic features of sudden acquired retinal degeneration syndrome (SARDS) and SARDS suspect dogs. ANIMALS STUDIED: Fourteen SARDS affected dogs, 11 age-, breed-, and sex-matched control dogs, and two SARDS suspect dogs. PROCEDURES: Spectral-domain optical coherence tomography (OCT) images were used to evaluate the quantitative features, including thickness, intereye asymmetry, and longitudinal changes in retinal layer thickness and the qualitative features, including retinal architecture and vitreous haze. RESULTS: Mean outer retinal layer thickness (ORT), outer nuclear layer thickness (ONL), and photoreceptor layer thickness (PRL) were significantly lower in the SARDS group, whereas mean inner retinal layer thickness was significantly higher in the SARDS group than in the control group. While thickness values of all retinal layers did not differ significantly between paired eyes in each group, the absolute intereye asymmetries in the ORT (p < .0001), ONL (p = .008), and PRL (p < .0001) were significantly higher in the SARDS group than in the control group. Some SARDS patients and SARDS suspects had a greater PRL than the control group, and serial OCT evaluation showed an increase in PRL in one SARDS suspect. Vitreous haze severity was greater in the SARDS group than in the control group (vitreous relative intensity, p = .030). CONCLUSIONS: We described the OCT features of SARDS patients and suspects. In particular, PRL thickening in the SARDS suspects might indicate an early change in SARDS. Although further studies are needed, this finding might provide new insights into the pathogenesis of SARDS.

Novel insights into chorioretinal and juxtapapillary colobomas by optical coherence tomography.

PURPOSE: The purpose was to describe the in vivo microanatomy of typical and atypical chorioretinal and juxtapapillary colobomas in the dog. METHODS: Three cross-breed dogs were found to be affected with colobomas. Two of the cases were NEHJ1 homozygous and Collie Eye Anomaly (CEA) affected and had the typical optic nerve head colobomas seen with the disease. The third case had an unexpected atypical coloboma. In vivo retinal photography and non-invasive retinal imaging by confocal scanning laser ophthalmoscope (cSLO) and optical coherence tomography (OCT) were done, and the eye affected with the atypical coloboma was collected and processed for histopathological evaluation. RESULTS: The majority of the defining features within the CEA defects were similar, with the extent of change to the choroid being of note. Similar to the first two cases, the atypical coloboma demonstrated absent normal retina, RPE, and choroid within the coloboma. Prominent intercalary membranes and vitreal strands attached to the depth of the coloboma were also apparent in all affected eyes. However, unlike the CEA-associated colobomas, the atypical coloboma possessed normal choroid surrounding the lesion and the depth of the lesion was apparent throughout. CONCLUSIONS: Advanced retinal imaging enables the appreciation of microanatomical changes that occur in the living eye. The ability of OCT to enhance visualization of abnormal retinal structures and detect subtle neurosensory retinal defects has allowed for the in vivo characterization of features observed in typical and atypical colobomas, as well as the appreciation of some of the resulting structural changes not visible by ophthalmoscopy alone.

Aqueous angiography in pre-glaucomatous and glaucomatous ADAMTS10-mutant canine eyes: A pilot study.

OBJECTIVE: To evaluate intravenous scleral and intracameral aqueous angiography in normotensive (n = 4) and hypertensive glaucomatous (n = 6) ADAMTS10-mutant canine eyes. ANIMALS STUDIED: Ten ADAMTS10-mutant dogs were used in this study. PROCEDURES: Dogs were sedated and one eye from each dog underwent scleral angiography following intravenous injection of 0.25% indocyanine green (ICG). After a 24-h recovery period, the same eye underwent aqueous angiography via intracameral administration of ICG. Imaging of identical scleral sectors from the same eye was performed using a Heidelberg Spectralis® Confocal Scanning Laser Ophthalmoscope. Intrascleral vessel depth and lumen diameters were measured using Heidelberg Spectralis® optical coherence tomography and computer software. RESULTS: Scleral angiography permitted visualization of vascular components associated with conventional aqueous humor outflow pathways with an average time from injection to fluorescence of 35.8 ± 10.6 s (mean ± SD). Two normotensive eyes (2/10;20%) demonstrated turbulent dye movement, while 4 hypertensive eyes (4/10;40%) exhibited laminar flow. Aqueous angiography demonstrated dye fluorescence within the post-trabecular conventional aqueous humor outflow pathways in all 10 eyes at 34.3 ± 11.0 s post-injection. Sectoral and dynamic outflow patterns were observed primarily within the superotemporal sector in nine eyes (9/10; 90%). Seven eyes (7/10; 70%) demonstrated pulsatile dye movement and five eyes (5/10; 50%) exhibited laminar flow. The degree of laminar movement of dye was greatest in hypertensive eyes. Vessel lumen diameters measured 133.85 ± 28.36 µm and 161.18 ± 6.02 µm in hypertensive and normotensive eyes, respectively. CONCLUSIONS: Aqueous angiography allowed for visualization of fluorescent dye in the superotemporal sclera. Laminar flow and smaller lumen vessels were observed mainly in hypertensive eyes.