RESUMEN
OBJECTIVE: To characterize functional and anatomic sequelae of a bleb induced by subretinal injection. METHODS: Subretinal injections (100 µL) of balanced salt solution were placed in the superotemporal macula of 1 eye in 3 cynomolgus macaques. Fellow eyes received intravitreal injections (100 µL) of balanced salt solution. Fundus photography, ocular coherence tomography, and multifocal electroretinography were performed before and immediately after injection and again at intervals up to 3 months postinjection. Histopathologic analyses included transmission electron microscopy and immunohistochemistry for glial fibrillary acidic protein, rhodopsin, M/L-cone opsin, and S-cone opsin. RESULTS: Retinas were reattached by 2 days postinjection (seen by ocular coherence tomography). Multifocal electroretinography waveforms were suppressed post-subretinal injection within the subretinal injection bleb and, surprisingly, also in regions far peripheral to this area. Multifocal electroretinography amplitudes were nearly completely recovered by 90 days. The spectral-domain ocular coherence tomography inner segment-outer segment line had decreased reflectivity at 92 days. Glial fibrillary acidic protein and S-cone opsin staining were unaffected. Rhodopsin and M/L-cone opsins were partially displaced into the inner segments. Transmission electron microscopy revealed disorganization of the outer segment rod (but not cone) discs. At all postinjection intervals, eyes with intravitreal injection were similar to baseline. CONCLUSIONS: Subretinal injection is a promising route for drug delivery to the eye. Three months post-subretinal injection, retinal function was nearly recovered, although reorganization of the outer segment rod disc remained disrupted. Understanding the functional and anatomic effects of subretinal injection is important for interpretation of the effects of compounds delivered to the subretinal space. CLINICAL RELEVANCE: Subretinal injection is a new potential route for drug delivery to the eye. Separating drug effects from the procedural effects is critical.
Asunto(s)
Acetatos/administración & dosificación , Minerales/administración & dosificación , Retina/efectos de los fármacos , Retina/fisiología , Cloruro de Sodio/administración & dosificación , Animales , Combinación de Medicamentos , Sistemas de Liberación de Medicamentos , Electrorretinografía , Proteína Ácida Fibrilar de la Glía/metabolismo , Inmunohistoquímica , Inyecciones Intravítreas , Macaca fascicularis , Microscopía Electrónica , Oftalmoscopía , Opsinas/metabolismo , Retina/metabolismo , Retina/ultraestructura , Rodopsina/metabolismo , Tomografía de Coherencia ÓpticaRESUMEN
PURPOSE: To analyze brightness, contrast, and color balance of digital versus film retinal images in a multicenter clinical trial, to propose a model image from exemplars, and to optimize both image types for evaluation of age-related macular degeneration (AMD). METHODS: The Age-Related Eye Disease Study 2 (AREDS2) is enrolling subjects from 90 clinics, with three quarters of them using digital and one quarter using film cameras. Image brightness (B), contrast (C), and color balance (CB) were measured with three-color luminance histograms. First, the exemplars (film and digital) from expert groups were analyzed, and an AMD-oriented model was constructed. Second, the impact of B/C/CB on the appearance of typical AMD abnormalities was analyzed. Third, B/C/CB in AREDS2 images were compared between film (156 eyes) and digital (605 eyes), and against the model. Fourth, suboptimal images were enhanced by adjusting B/C/CB to bring them into accord with model parameters. RESULTS: Exemplar images had similar brightness, contrast, and color balance, supporting an image model. Varying a specimen image through a wide range of B/C/CB revealed greatest contrast of drusen and pigment abnormalities against normal retinal pigment epithelium with the model parameters. AREDS2 digital images were more variable than film, with lower correspondence to our model. Ten percent of digital were too dim and 19% too bright (oversaturated), versus 1% and 4% of film, respectively. On average, digital had lower green channel contrast (giving less retinal detail) than film. Overly red color balance (weaker green) was observed in 23% of digital versus 8% of film. About half of digital (but fewer film) images required enhancement before AMD grading. After optimization of both image types, AREDS2 image quality was judged as good as that in AREDS (all film). CONCLUSIONS: A histogram-based model, derived from exemplars, provides a pragmatic guide for image analysis and enhancement. In AREDS2, the best digital images matched the best film. Overall, however, digital provided lower contrast of retinal detail. Digital images taken with higher G-to-R ratio showed better brightness and contrast management. Optimization of images in the multicenter study helps standardize documentation of AMD (ClinicalTrials.gov NCT00345176).
Asunto(s)
Degeneración Macular/diagnóstico , Fotograbar/normas , Retina/patología , Procesamiento de Señales Asistido por Computador , Anciano , Anciano de 80 o más Años , Color , Femenino , Humanos , Luz , Masculino , Persona de Mediana Edad , Fotograbar/métodosRESUMEN
OBJECTIVE: To compare gradings of lesions associated with age-related macular degeneration (AMD) from digital and stereoscopic film images. DESIGN: Instrument validation study. PARTICIPANTS: Sixty-two subjects (124 eyes) with varying degrees of AMD, including no AMD. METHODS: Images of the optic disc and macula were taken using a 45 degrees digital camera (6.3 megapixels) through dark-adapted pupils and pharmacologically dilated pupils. In addition, 30 degrees stereoscopic retinal film images were taken through pharmacologically dilated pupils of the same eyes. All images were graded for drusen size, type, and area; pigmentary abnormalities; geographic atrophy; and neovascular lesions using the modified Wisconsin Age-Related Maculopathy Grading System. Exact agreement and unweighted kappa scores were calculated for paired gradings resulting from digital and film images. MAIN OUTCOME MEASURE: Agreement between gradings obtained from stereoscopic slide transparencies and digital nonstereoscopic images. RESULTS: Exact agreement between gradings of digital and stereoscopic film images taken through pharmacologically dilated pupils was 91% (kappa = 0.85) for the categories of none, early AMD, and late AMD. Exact agreement for gradings of digital images taken through dark-adapted pupils compared with gradings of film images was 80% (kappa = 0.69). Exact agreement for gradings of digital images captured through dark-adapted and pharmacologically dilated pupils was 86% (kappa = 0.78). In addition, kappa scores for agreement between different approaches for individual lesions were moderate to almost perfect. CONCLUSIONS: Gradings resulting from high-resolution digital images, especially when the pupil is pharmacologically dilated, are comparable with those resulting from film-based images. We conclude that digital imaging of the retina is useful for epidemiological studies of AMD.