Spectral domain optical coherence tomography evaluation of the feline optic nerve and peripapillary retina

Abstract

Objective To describe and to establish normative data for the feline optic nerve and peripapillary retina using SD‐OCT (Spectralis® HRA+OCT2). Methods Slit‐lamp biomicroscopy and rebound tonometry were performed in seven male‐intact (0.65 ± 0.02 years;4.34 ± 0.33 kg) and seven female‐spayed (0.74 ± 0.03 years; 3.13 ± 0.28 kg) cats. All eyes were pharmacologically dilated with 1% tropicamide prior to indirect ophthalmoscopy examination. Animals were then placed under general anesthesia. Optic nerve and peripapillary retinal morphology was evaluated using SD‐OCT device by infrared imaging and volumetric scans (circle and radial). Optic disc area, optic cup depth, peripapillary retinal thickness (RT), and retinal nerve fiber layer thickness (RNFLT) were measured. The RNFLT:RT ratio was calculated in the superior, nasal, temporal, and inferior peripapillary region. Results Intraocular pressure in all cats was 20.68 ± 4.87 mm Hg (mean ± SD). Mean RT and RNFL were thickest in the superior retina (264.7 ± 13.95 µm and 70.22 ± 11.78 µm, respectively) (P < 0.0001). Inferior RT was significantly thinner than nasal and temporal retina (P = 0.0013 and P = 0.0010, respectively). The RNFLT:RT was significantly higher in the superior retina (0.27 ± 0.04) (P < 0.0001). Optic disc area OU was 1.39 ± 0.26 mm2. Optic cup depth OU was 168.36 ± 67.74 µm. All parameters tested were not affected by gender, intraocular pressure, body weight, or tested eye. Most eyes had a Bergmeister papilla that was only visible on OCT. Some animals had a recessed area over the center of the ONH meniscus. Conclusion Normative peripapillary ONH OCT data have been introduced. A Bergmeister papillae is commonly seen in young cats on OCT examination. OCT is a helpful tool to evaluate the retina in cats.

Diffusion tensor imaging of the visual pathway in dogs with primary angle‐closure glaucoma

“…Diffusion weighted imaging provides an alternative approach to early evaluation of glaucoma, a group of diseases characterized by the loss of RGCs and their axons. The technique we describe does overcome a major limitation associated with OCT, which is increasingly reported in the veterinary literature for assessment of the retina and ONH 46‐63 . Canine glaucoma is commonly associated with corneal opacities and drug‐induced miosis which both preclude reliable OCT assessment, but do not affect measurements of the white matter tracts using DTI.…”

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

“…De Ramus et al 30 presented a uniform standard for murine OCT layer nomenclature, in which they identified the choroid as an intensely hyperreflective band directly external to the RPE/BM. Detailed images of outer retinal layer anatomy visible on canine 1,10,17,21,31–34 and feline 16,35 SD‐OCT scans have been published. Unfortunately, a consensus nomenclature of the outer retinal bands distinguishable on SD‐OCT scans, similar to that in humans 29 and mice, 30 has not been established in other species.…”

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

“…Several studies have shown that spectral domain OCT (SD-OCT) is a reliable method to evaluate different retinal layers and optic nerve morphology in colobomas in dogs, 15 in healthy or glaucomatous cats. [16][17][18] Recently, it has been published that outer retinal band and choriocapillaris can be identified in healthy dogs and cats, 19 and different vascular layers of the retina and choroid are nicely evaluated by OCT-A in cats. 20 The present report describes the clinical case of bilateral corneal dermoids associated with bilateral choroidoscleral colobomas in a cat, its SD-OCT fundus evaluation, the surgical outcome and the follow-up of lesions up to 18 months.…”