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Adaptive optics is a relatively new field, yet it is spreading rapidly and allows new questions to be asked about how the visual system is organized. The editors of this feature issue have posed a series of question to scientists involved in using adaptive optics in vision science. The questions are focused on three main areas. In the first we investigate the use of adaptive optics for psychophysical measurements of visual system function and for improving the optics of the eye. In the second, we look at the applications and impact of adaptive optics on retinal imaging and its promise for basic and applied research. In the third, we explore how adaptive optics is being used to improve our understanding of the neurophysiology of the visual system.
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Fenômenos Fisiológicos Oculares , Óptica e Fotônica , Retina/fisiologia , Transtornos da Visão/reabilitação , Percepção Visual/fisiologia , Animais , Humanos , Psicofísica , Transtornos da Visão/fisiopatologia , Visão Ocular/fisiologiaRESUMO
The most common cause of untreatable vision loss is dysfunction of the retina. Conditions, such as age-related macular degeneration, diabetic retinopathy and glaucoma remain leading causes of untreatable blindness worldwide. Various stem cell approaches are being explored for treatment of retinal regeneration. The rationale for using bone marrow stem cells to treat retinal dysfunction is based on preclinical evidence showing that bone marrow stem cells can rescue degenerating and ischemic retina. These stem cells have primarily paracrine trophic effects although some cells can directly incorporate into damaged tissue. Since the paracrine trophic effects can have regenerative effects on multiple cells in the retina, the use of this cell therapy is not limited to a particular retinal condition. Autologous bone marrow-derived stem cells are being explored in early clinical trials as therapy for various retinal conditions. These bone marrow stem cells include mesenchymal stem cells, mononuclear cells and CD34+ cells. Autologous therapy requires no systemic immunosuppression or donor matching. Intravitreal delivery of CD34+ cells and mononuclear cells appears to be tolerated and is being explored since some of these cells can home into the damaged retina after intravitreal administration. The safety of intravitreal delivery of mesenchymal stem cells has not been well established. This review provides an update of the current evidence in support of the use of bone marrow stem cells as treatment for retinal dysfunction. The potential limitations and complications of using certain forms of bone marrow stem cells as therapy are discussed. Future directions of research include methods to optimize the therapeutic potential of these stem cells, non-cellular alternatives using extracellular vesicles, and in vivo high-resolution retinal imaging to detect cellular changes in the retina following cell therapy.
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Células da Medula Óssea/classificação , Células-Tronco Mesenquimais/citologia , Doenças Retinianas/cirurgia , Transplante de Células-Tronco/métodos , Animais , HumanosRESUMO
PURPOSE: Optical coherence tomography (OCT) has enabled "virtual biopsy" of the living human retina, revolutionizing both basic retina research and clinical practice over the past 25 years. For most of those years, in parallel, adaptive optics (AO) has been used to improve the transverse resolution of ophthalmoscopes to foster in vivo study of the retina at the microscopic level. Here, we review work done over the last 15 years to combine the microscopic transverse resolution of AO with the microscopic axial resolution of OCT, building AO-OCT systems with the highest three-dimensional resolution of any existing retinal imaging modality. METHODS: We surveyed the literature to identify the most influential antecedent work, important milestones in the development of AO-OCT technology, its applications that have yielded new knowledge, research areas into which it may productively expand, and nascent applications that have the potential to grow. RESULTS: Initial efforts focused on demonstrating three-dimensional resolution. Since then, many improvements have been made in resolution and speed, as well as other enhancements of acquisition and postprocessing techniques. Progress on these fronts has produced numerous discoveries about the anatomy, function, and optical properties of the retina. CONCLUSIONS: Adaptive optics OCT continues to evolve technically and to contribute to our basic and clinical knowledge of the retina. Due to its capacity to reveal cellular and microscopic detail invisible to clinical OCT systems, it is an ideal companion to those instruments and has the demonstrable potential to produce images that can guide the interpretation of clinical findings.
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Pesquisa Biomédica/tendências , Oftalmologia/tendências , Óptica e Fotônica , Retina/diagnóstico por imagem , Tomografia de Coerência Óptica/instrumentação , Desenho de Equipamento , HumanosRESUMO
PURPOSE: Because human bone marrow (BM) CD34+ stem cells home into damaged tissue and may play an important role in tissue repair, this pilot clinical trial explored the safety and feasibility of intravitreal autologous CD34+ BM cells as potential therapy for ischemic or degenerative retinal conditions. METHODS: This prospective study enrolled six subjects (six eyes) with irreversible vision loss from retinal vascular occlusion, hereditary or nonexudative age-related macular degeneration, or retinitis pigmentosa. CD34+ cells were isolated under Good Manufacturing Practice conditions from the mononuclear cellular fraction of the BM aspirate using a CliniMACs magnetic cell sorter. After intravitreal CD34+ cell injection, serial ophthalmic examinations, microperimetry/perimetry, fluorescein angiography, electroretinography (ERG), optical coherence tomography (OCT), and adaptive optics OCT were performed during the 6-month follow-up. RESULTS: A mean of 3.4 million (range, 1-7 million) CD34+ cells were isolated and injected per eye. The therapy was well tolerated with no intraocular inflammation or hyperproliferation. Best-corrected visual acuity and full-field ERG showed no worsening after 6 months. Clinical examination also showed no worsening during follow-up except among age-related macular degeneration subjects in whom mild progression of geographic atrophy was noted in both the study eye and contralateral eye at 6-month follow-up, concurrent with some possible decline on multifocal ERG and microperimetry. Cellular in vivo imaging using adaptive optics OCT showed changes suggestive of new cellular incorporation into the macula of the hereditary macular degeneration study eye. CONCLUSIONS: Intravitreal autologous BM CD34+ cell therapy appears feasible and well tolerated in eyes with ischemic or degenerative retinal conditions and merits further exploration. (ClinicalTrials.gov number, NCT01736059.).
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Antígenos CD34/imunologia , Células da Medula Óssea/imunologia , Transplante de Células/métodos , Isquemia/terapia , Degeneração Retiniana/terapia , Adulto , Idoso , Idoso de 80 Anos ou mais , Células da Medula Óssea/citologia , Feminino , Angiofluoresceinografia , Seguimentos , Fundo de Olho , Humanos , Injeções Intravítreas , Isquemia/diagnóstico , Isquemia/imunologia , Masculino , Estudos Prospectivos , Degeneração Retiniana/diagnóstico , Degeneração Retiniana/imunologia , Doenças Retinianas/diagnóstico , Doenças Retinianas/imunologia , Doenças Retinianas/terapia , Resultado do Tratamento , Acuidade Visual , Adulto JovemRESUMO
We explored the perception of image focus in patients with cataracts, and how this perception changed following cataract removal and implantation of an intraocular lens. Thirty-three patients with immature senile cataract and with normal retinal function were tested before surgery and 2 days after surgery, with 18 of the patients retested again at 2 months following surgery. The subjective focus of natural images was quantified in each session by varying the slope of the image amplitude spectra. At each time, short-term adaptation to the spectral slope was also determined by repeating the measurements after exposure to images with blurred or sharpened spectra. Despite pronounced acuity deficits, before surgery images appeared "best-focused" when they were only slightly blurred, consistent with a strong compensation for the acuity losses. Post-operatively, the image slopes that were judged "in focus" before surgery appeared too sharp. This bias remained strong at 2 months, and was independent of the rapid blur aftereffects induced by viewing filtered images. The focus settings tended to renormalize more rapidly in patients with higher post-operative acuity, while acuity differences were unrelated to the magnitude of the short-term blur aftereffects. Our results suggest that subjective judgments of image focus are largely compensated as cataracts develop, but potentially through a very long-term form of adaptation that results in persistent biases after the cataract is removed.
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Adaptação Ocular/fisiologia , Extração de Catarata , Catarata/fisiopatologia , Implante de Lente Intraocular , Acuidade Visual/fisiologia , Idoso , Idoso de 80 Anos ou mais , Análise de Variância , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estimulação Luminosa/métodosRESUMO
PURPOSE: To report the results of imaging using high-resolution, Fourier domain anterior segment optical coherence tomography (AS-OCT) to evaluate patients with a type 1 Boston Keratoprosthesis (KPro). METHODS: We performed a retrospective comparative study of patients in whom we implanted the Boston KPro. A total of 26 eyes of 23 patients from the Cornea Service at the University of California Davis Eye Center were included. Subjects were evaluated with the Spectralis AS-OCT (Heidelberg Engineering GmbH). RESULTS: Preoperative diagnoses for KPro surgery included failed corneal transplant (69%), chemical burn (23%), and aniridia (8%). The average age of patients was 63.2 years (range, 17-88 years). Fifty-four percent of the patients were female. The mean duration between the KPro surgery and the acquisition of high-resolution AS-OCT imaging was 35.8 months (range, 2-90 months). The most commonly observed finding was retroprosthetic membrane formation, which we found in 77% of KPro eyes. In 65% of KPro eyes, we identified epithelium behind the front plate, and in 54%, we identified an epithelial lip over the anterior surface of the KPro front plate. In 31% of KPro eyes, we identified periprosthetic cysts, gaps or spaces, and thinning in the corneal carrier graft. CONCLUSIONS: Fourier domain AS-OCT is a useful noninvasive imaging technique in patients with a KPro and provides the ability to identify changes that are sometimes difficult to appreciate by clinical evaluation. The higher resolution Fourier domain systems may aid in the clinical diagnosis and management of pathology that might not be imaged with instruments of lower resolution. AS-OCT has the potential for monitoring the anatomic stability of an implanted KPro and may also help to monitor for complications. Moreover, high-resolution imaging may enhance our understanding of periprosthetic anatomy.
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Aniridia/cirurgia , Segmento Anterior do Olho/patologia , Doenças da Córnea/cirurgia , Próteses e Implantes , Implantação de Prótese , Tomografia de Coerência Óptica/métodos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Análise de Fourier , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Adulto JovemRESUMO
PURPOSE: To determine the long-term effects of stereotactic fractionated external beam radiation on eyes treated for neovascular age-related macular degeneration. METHODS: A retrospective review of all eyes treated with stereotactic fractionated external beam radiation (20-40 Gy, 2-Gy fractions) between 1997 and 2000 was performed to identify eyes with ≥ 2-year follow-up for analysis. A subset was imaged prospectively using a high-resolution Fourier-domain optical coherence tomography. RESULTS: Among 94 eyes treated, 33 eyes (32 subjects) had ≥ 2-year follow-up information (mean follow-up, 6.2 years; range, 2-10 years). Final visual acuity ranged from 20/50 to no light perception. Final macular findings included central geographic atrophy (49%), disciform scar (30%), and active choroidal neovascular membrane (9%). Fourier-domain optical coherence tomography images of three eyes with geographic atrophy revealed photoreceptor layer loss within areas of geographic atrophy with intact retinal morphology in areas of radiation exposure outside geographic atrophy. Radiation retinopathy was suspected in 18% and confirmed by fluorescein angiography in 15%, ranging from mild to neovascular glaucoma/phthisis bulbi (2 eyes). Mean time from stereotactic fractionated external beam radiation to development of radiation retinopathy was 5.4 years (range, 1-10 years). CONCLUSION: A moderate rate of delayed radiation retinopathy was noted in eyes with neovascular age-related macular degeneration treated with stereotactic fractionated external beam radiation. Geographic atrophy was a common finding.
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Neovascularização de Coroide/radioterapia , Degeneração Macular/radioterapia , Células Fotorreceptoras de Vertebrados/efeitos da radiação , Lesões por Radiação/etiologia , Radioterapia/efeitos adversos , Idoso , Idoso de 80 Anos ou mais , Neovascularização de Coroide/diagnóstico , Fracionamento da Dose de Radiação , Feminino , Angiofluoresceinografia , Seguimentos , Análise de Fourier , Atrofia Geográfica/diagnóstico , Atrofia Geográfica/etiologia , Humanos , Degeneração Macular/diagnóstico , Masculino , Pessoa de Meia-Idade , Doses de Radiação , Lesões por Radiação/diagnóstico , Estudos Retrospectivos , Técnicas Estereotáxicas , Fatores de Tempo , Tomografia de Coerência Óptica , Acuidade Visual/fisiologiaRESUMO
Using high-resolution spectral-domain optical coherence tomography (SD-OCT) and adaptive optics (AO) imaging, photoreceptor damage in a patient with a central macular arteriovenous malformation (AVM) and otherwise unexplained progressive vision loss was demonstrated. This patient presented with a central scotoma, a macular AVM, and no evidence of macular edema, retinal hemorrhage, or subretinal fluid. Fluorescein angiography (FA) did not reveal leakage. Over 28 years, her vision progressively worsened from 20/25 to 20/400. Both time-domain OCT and FA did not reveal any significant retinal abnormality. However, high-resolution SD-OCT imaging revealed clear disorganization of the outer segments and focal photoreceptor disruption adjacent to the AVM. En face AO images further revealed loss of the photoreceptors in these regions. This case demonstrates the unique finding of progressive vision loss in a patient with a congenital retinal AVM, and how high-resolution imaging can detect structural changes of the retina in patients with otherwise unexplained vision loss.
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Exophytic retinal capillary hemangiomas (RCH) can be a diagnostic challenge in subjects without von Hippel-Lindau disease (VHL). This report of two cases describes the optical coherence tomographic (OCT) characteristics of RCH in two eyes of a subject with VHL and in one eye of an otherwise normal subject. Three different OCT instruments were used (Stratus, Cirrus and/or custom high resolution Fourier-domain OCT with 4.5 mum axial resolution) depending on availability. All instruments localized the tumor to the outer retina. A sharp border between the tumor and overlying inner retina was noted. The tumor bulged into the subretinal space and showed marked shadowing. Associated cystoid macular edema and subretinal fluid were noted. High-resolution Fourier-domain OCT showed a focal photoreceptor layer rip in the adjacent tumor-free macula in one eye with poor vision after treatment. OCT may be a useful tool in diagnosing RCH and studying associated morphologic changes.
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PURPOSE: To evaluate the influence of spherical aberration on contrast sensitivity using adaptive optics. SETTING: Vision Science and Advanced Retinal Imaging Laboratory, Department of Ophthalmology & Vision Science, University of California, Davis Medical Center, Sacramento, California, USA. METHODS: Contrast sensitivity at 8 cycles per degree was evaluated using an adaptive optics system that permitted aberrations to be measured with a Hartmann-Shack wavefront sensor and controlled by a 109 actuator continuous-surface deformable mirror that was at a plane conjugate to the observer's pupil. Vertical Gabor patches were viewed through a 6.3 mm diameter pupil conjugate aperture. Contrast sensitivity was measured with the deformable mirror set to produce 1 of 5 spherical aberration profiles (-0.2 to +0.2 microm). Contrast sensitivity over the range of spherical aberration was fitted with a polynomial function. RESULTS: Three subjects (age 21 to 24 years) participated. The measured total mean spherical aberration resulting from the spherical aberration profiles produced by the deformable mirror was between -0.15 microm and +0.25 microm. The peak contrast sensitivity of this function for the 3 subjects combined occurred at +0.06 microm of spherical aberration. The peak contrast sensitivity was also achieved with positive spherical aberration for each subject's data fitted individually (mean 0.09). CONCLUSION: There was intersubject variability in the measurements; however, the mean visual performance was best with the introduction of a small positive spherical aberration.
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Sensibilidades de Contraste/fisiologia , Óculos , Lentes Intraoculares , Erros de Refração/fisiopatologia , Feminino , Humanos , Masculino , Óptica e Fotônica , Psicofísica , Acuidade Visual/fisiologia , Adulto JovemRESUMO
PURPOSE: To describe a case of fine retinal striae visualized using an adaptive optics flood illuminated (AO-flood) fundus camera in a patient with vision loss from an idiopathic macular epiretinal membrane (ERM). METHODS: A case report of a 48-year-old woman with recent vision loss from ERM imaged using an AO-flood fundus camera and high resolution Fourier-domain optical coherence tomography (Fd-OCT) before and 3 months after vitrectomy. RESULTS: Visual acuity improved from 20/70 to 20/20 after vitrectomy. Preoperative Fd-OCT showed severe cystoid macular edema with irregularities in the outer nuclear layer which consists of cell bodies of photoreceptors. Preoperative AO-flood en face images showed dark linear striae of approximately 10 µm width overlying the cone mosaic that improved following surgery, concurrent with improvement in visual acuity and morphologic changes on Fd-OCT. CONCLUSION: Microstructural changes within the retinal layers resulting from macular traction from ERM can be visualized using an AO-flood fundus camera and Fd-OCT. They can appear as fine linear striae in AO-flood en face images. Further studies are needed to correlate these changes with vision loss associated with this condition.
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PURPOSE: To study the integrity of inner and outer retinal layers in patients with various types of optic neuropathy by using high-resolution imaging modalities. METHODS: Three high-resolution imaging systems constructed at the University of California Davis were used to acquire retinal images from patients with optic neuropathy: (1) adaptive optics (AO)-flood-illuminated fundus camera, (2) high-resolution Fourier domain optical coherence tomography (FDOCT), and (3) adaptive optics-Fourier domain optical coherence tomography (AO-FDOCT). The AO fundus camera provides en face images of photoreceptors whereas cross-sectional images (B-scans) of the retina are obtained with both FDOCT and AO-FDOCT. From the volumetric FDOCT data sets, detailed thickness maps of a three-layer complex consisting of the nerve fiber (NF), ganglion cell (GC), and inner plexiform (IP) layers were created. The number of visible cones in the en face images of photoreceptors was then compared with visual sensitivity maps from Humphrey visual field (HVF; Carl Zeiss Meditec, Inc., Dublin, CA) testing, as well as FDOCT and AO-FDOCT images, including the thickness maps of the NF-GC-IP layer complex. Five types of optic neuropathy were studied: (1) optic neuritis with multiple sclerosis (MS), (2) idiopathic intracranial hypertension (pseudotumor cerebri), (3) nonarteritic anterior ischemic optic neuropathy (NAION), (4) optic nerve head drusen with NAION, and (5) systemic lupus erythematosus with MS and arthritis. RESULTS: With permanent visual field loss and thinning of the NF-GC-IP layer complex, cone photoreceptors showed structural changes, making them less reflective, which caused the appearance of dark spaces in the en face images (hence, reduced number of visible cones) and indistinct outer retinal layers in OCT images. However, when the visual field loss was only transient, with a normal NF-GC-IP layer complex, there were no detectable abnormalities in cone photoreceptors (i.e., they were densely packed and had distinct photoreceptor layering in the OCT images). CONCLUSIONS: Cone photoreceptors show structural changes when there is permanent damage to overlying inner retinal layers. There was a positive relation between the thickness of the three-layer inner retinal complex, visual sensitivity, and integrity of the cone mosaic.
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Diagnóstico por Imagem/métodos , Técnicas de Diagnóstico Oftalmológico , Doenças do Nervo Óptico/diagnóstico , Células Fotorreceptoras Retinianas Cones/patologia , Adulto , Feminino , Análise de Fourier , Humanos , Masculino , Pessoa de Meia-Idade , Esclerose Múltipla/complicações , Fibras Nervosas/parasitologia , Drusas do Disco Óptico/diagnóstico , Neuropatia Óptica Isquêmica/diagnóstico , Fotografação/métodos , Pseudotumor Cerebral/diagnóstico , Células Ganglionares da Retina/patologia , Tomografia de Coerência Óptica/métodos , Transtornos da Visão/diagnóstico , Campos VisuaisRESUMO
PURPOSE: To study the anatomic details of retinal angiomatous proliferation (RAP) in patients with age-related macular degeneration (AMD) using high-resolution Fourier-domain optical coherence tomography (Fd-OCT) and its three-dimensional reconstructions. METHODS: A Fd-OCT instrument was used to image five patients clinically diagnosed with RAP. A series of 100 raster-scanned B-scans centered over the macula was registered and rendered as a three-dimensional volume. These retinal structures were analyzed for anatomic details of the RAP lesions. RESULTS: The RAP lesion could be identified within the retina on Fd-OCT in all five cases. Fd-OCT images of the first four cases revealed areas of intraretinal neovascularization (IRN) in the deep retina adjacent to a pigment epithelial detachment (PED). There was neovascular proliferation anteriorly and posteriorly through a break in the retinal pigment epithelium (RPE). In three of the four cases, Bruch membrane remained intact. There was no identifiable choroidal neovascularization (CNV). The fifth case had both subretinal and sub-RPE neovascular membranes without a PED. CONCLUSION: Fd-OCT provides unprecedented in vivo detail of the anatomy of RAP lesions that nearly resembles histologic specimens. This study suggests that the initial neovascular process in RAP can originate either within the retina or in the sub-RPE space.
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Análise de Fourier , Neovascularização Retiniana/diagnóstico , Tomografia de Coerência Óptica/métodos , Idoso , Idoso de 80 Anos ou mais , Feminino , Angiofluoresceinografia , Humanos , Processamento de Imagem Assistida por Computador , Imageamento Tridimensional , Degeneração Macular/complicações , Masculino , Pessoa de Meia-Idade , Epitélio Pigmentado Ocular/patologia , Retina/patologia , Neovascularização Retiniana/etiologiaRESUMO
The optical density of the human crystalline lens progressively increases with age, the greatest increase in the visible spectrum being at short wavelengths. This produces a gradual shift in the spectral distribution of the light reaching the retina, yet color appearance remains relatively stable across the life span, implying that the visual system adapts to compensate for changes in spectral sensitivity. We explored properties of this adaptive renormalization by measuring changes in color appearance following cataract surgery. When the lens is removed, cataract patients often report a large perceptual shift in color appearance that can last for months. This change in color appearance was quantified for four cataract patients (63-84 years) by determining the chromaticity of stimuli that appeared achromatic before surgery, and at various intervals after surgery for up to 1 year. Stimuli were presented on a calibrated CRT as 9.5-deg spots, with 3-s duration and 3-s interstimulus intervals (ISIs). Chromaticity was adjusted by the subjects in CIE L*a*b* color space with luminance fixed at 32 cd/m2, on a dark background. We also estimated the optical density of the cataractous lens by comparing absolute scotopic thresholds from 410 nm to 600 nm before and after surgery. The results demonstrated that immediately following surgery there is a large increase in the short-wave light reaching the retina, mainly below 500 nm. The achromatic settings generally showed an initial large shift in the "yellow" direction after surgery that gradually (but never fully) returned to the original achromatic point before surgery. The shifts in the achromatic point occur over a number of months and appear to occur independently of the fellow eye.
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Extração de Catarata , Percepção de Cores/fisiologia , Percepção Visual/fisiologia , Adaptação Ocular/fisiologia , Discriminação Psicológica , Humanos , Cristalino , Período Pós-Operatório , Fatores de TempoRESUMO
BACKGROUND: Pancreatic insufficiency in cystic fibrosis (CF), even with replacement pancreatic enzyme therapy, is often associated with decreased carotenoid absorption. Because the macular pigment of the retina is largely derived from 2 carotenoids, lutein and zeaxanthin, the decreased serum concentrations seen in CF may have consequences for ocular and retinal health OBJECTIVES: Our aims were to determine plasma carotenoid concentrations, determine absorption and distribution of macular pigment, and assess retinal health and visual function in CF patients. DESIGN: In 10 adult CF patients (ages 21-47 y) and 10 age- and sex-matched healthy control subjects, we measured macular pigment density in vivo, measured serum lutein and zeaxanthin concentrations, and comprehensively assessed visual performance (including contrast sensitivity, color discrimination, and retinal function) under conditions of daylight illumination. RESULTS: Serum lutein and zeaxanthin were significantly reduced (P < 0.005) in CF patients ( +/- SD: 87 +/- 36.1 and 27 +/- 15.8 nmol/L, respectively) compared with control subjects (190 +/- 72.1 and 75 +/- 23.6 nmol/L, respectively). Although macular pigment optical density was significantly lower (P < 0.0001) in the CF group (0.24 +/- 0.11) than in the control group (0.53 +/- 0.12), no significant differences in visual function were observed. CONCLUSIONS: Adults with CF have dramatically low serum and macular concentrations of carotenoids (lutein and zeaxanthin), but their ocular status and visual function are surprisingly good. The clinical implications of low plasma concentrations of carotenoids in CF are yet to be clarified.
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Fibrose Cística/sangue , Luteína/sangue , Retina/metabolismo , beta Caroteno/sangue , Adulto , Estudos de Casos e Controles , Percepção de Cores , Estudos Transversais , Fibrose Cística/fisiopatologia , Eletrorretinografia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Xantofilas , Zeaxantinas , beta Caroteno/análogos & derivadosRESUMO
The human visual system undergoes continuous anatomical, physiological and functional changes throughout the life span. There is also continuous change in the spectral distribution and intensity of light reaching the retina from infancy through senescence, primarily due to changes in the absorption of short-wave light by the lens. Despite these changes in the retinal stimulus and the signals leaving the retina for perceptual analysis, color appearance is relatively stable during aging as measured by broadband reflective or self-luminous samples, the wavelengths of unique blue and yellow, and the achromatic locus. Measures of ocular media density for younger and older observers show, indeed, that color appearance is independent of ocular media density. This may be explained by a renormalization process that was demonstrated by measuring the chromaticity of the achromatic point before and after cataract surgery. There was a shift following cataract surgery (removal of a brunescent lens) that was initially toward yellow in color space, but over the course of months, drifted back in the direction of the achromatic point before surgery. The spatial characteristics of color mechanisms were quantified for younger and older observers in terms of chromatic perceptive fields and the chromatic contrast sensitivity functions. Younger and older observers differed with small spots or with chromatic spatial gratings near threshold, but there were no significant differences with larger spots or suprathreshold spatial gratings.