Optic neuropathy and diplopia from thyroid eye disease: update on pathophysiology and treatment

PURPOSE OF REVIEW

Thyroid eye disease (TED) is a disfiguring disease that can lead to neuro-ophthalmic manifestations including diplopia and optic neuropathy. The aim of this review is to shed light on the diagnosis of TED based on clinical examination findings and diagnostic imaging. We will also discuss gold standard as well as newly emerging therapies for TED.

RECENT FINDINGS

We discussed diagnostic criteria for TED and differentiating TED from other causes of binocular diplopia. We also reviewed the pathophysiology and differential diagnoses for dysthyroid optic neuropathy as well as recent developments on controversial causes. New imaging techniques are available for evaluation and prognosis of TED comorbidities. Most of the recent developments in TED have been focused on new treatment modalities that have thus far had promising results. We reviewed recently approved and novel potential therapies that are helpful in treating both diplopia and dysthyroid optic neuropathy.

SUMMARY

TED is a complicated disorder with many clinical manifestations as well as treatment modalities. Our aim of this review was to outline new developments in the diagnosis and management of TED.

Advances in ophthalmic structural and functional measures in multiple sclerosis: do the potential ocular biomarkers meet the unmet needs?

PURPOSE OF REVIEW

Multiple sclerosis is a heterogeneous disorder. Biomarkers to monitor disease activities are highly desirable especially because of the recent shift toward personalized medicine that coincides with the expansion of disease-modifying therapy. The visual system is highly involved in multiple sclerosis, and the rapid advancement of ophthalmic techniques has boosted the development of potential ocular biomarkers for multiple sclerosis management.

RECENT FINDINGS

Recent studies have found that the rapid thinning of the peripapillary retinal nerve fiber layer and ganglion cell-inner plexiform layer (GCIPL) occurs in the progressive stage. Furthermore, the inter-eye thickness difference of the GCIPL could be used in identifying unilateral optic neuritis to facilitate the early diagnosis of multiple sclerosis. Moreover, the retinal microvascular alterations measured as vessel density were found to be related to the disability and visual function, although a standardized protocol to measure retinal microvascular alterations has not been well established. Additionally, aberrant ocular motility, such as fixation microsaccades, can be used to measure disability objectively.

SUMMARY

The fast expansion of potential ocular biomarkers measured as retinal microstructural, microvascular, and ocular motility changes may facilitate the diagnosis and management of multiple sclerosis.

Retinal disease in the neurology clinic

PURPOSE OF REVIEW

Retinal disease can manifest with visual symptoms similar to those which result from central nervous system disorders. We provide a framework for considering retinal causes of common visual complaints presenting to a neurology clinic.

RECENT FINDINGS

Technological advances have afforded quicker detection and a more thorough understanding of these retinal entities and are crucial to consider when evaluating visual complaints in the neurology clinic.

SUMMARY

It is essential to maintain a working knowledge of common retinal conditions that symptomatically overlap with common neurologic conditions. Furthermore, the ophthalmoscopic exam and retinal imaging modalities can both aid in the diagnosis and workup of visual complaints and neurologic disease.

Visualizing the dynamic change of Ocular Response Analyzer waveform using Variational Autoencoder in association with the peripapillary retinal arteries angle

The aim of the current study is to identify possible new Ocular Response Analyzer (ORA) waveform parameters related to changes of retinal structure/deformation, as measured by the peripapillary retinal arteries angle (PRAA), using a generative deep learning method of variational autoencoder (VAE). Fifty-four eyes of 52 subjects were enrolled. The PRAA was calculated from fundus photographs and was used to train a VAE model. By analyzing the ORA waveform reconstructed (noise filtered) using VAE, a novel ORA waveform parameter (Monot1-2), was introduced, representing the change in monotonicity between the first and second applanation peak of the waveform. The variables mostly related to the PRAA were identified from a set of 41 variables including age, axial length (AL), keratometry, ORA corneal hysteresis, ORA corneal resistant factor, 35 well established ORA waveform parameters, and Monot1-2, using a model selection method based on the second-order bias-corrected Akaike information criterion. The optimal model for PRAA was the AL and six ORA waveform parameters, including Monot1-2. This optimal model was significantly better than the model without Monot1-2 (p = 0.0031, ANOVA). The current study suggested the value of a generative deep learning approach in discovering new useful parameters that may have clinical relevance.

New imaging systems in diabetic retinopathy

Various imaging modalities are of significant utility in the screening, grading, treatment, and follow-up of the different stages of diabetic retinopathy (DR) and diabetic macular edema. Color stereographic photography, fluorescein angiography, and optical coherence tomography (OCT) have been the gold standard for DR imaging for years. Besides these tools, newer technologies are gaining validation and popularity, such as fundus autofluorescence and OCT angiography. Furthermore, widefield retinography and ultra-widefield retinography have been introduced for a more comprehensive evaluation of the medium-far and very-far retinal peripheries, which is crucial for the assessment of the diverse manifestations of the disease. The aim of this review is to illustrate the recent advancements of the imaging systems for diagnosing DR, with a focus on the newest and noninvasive diagnostic tools.

Modern neuro-ophthalmological evaluation of patients with pituitary disorders

Pituitary adenomas can manifest as ophthalmological symptoms, such as decreased vision, impaired visual field or diplopia. It is important to recognize these neuro-ophthalmological syndromes to achieve early diagnosis and treatment and to improve prognosis. Currently, ophthalmological examination includes precise measuring instruments, such as optical coherence tomography (OCT), which allows the evaluation of optic atrophy related to compression of the anterior optic tract. These measurements are reproducible and are useful for diagnostic and prognostic evaluation. In this review, we describe the ophthalmological syndromes associated with pituitary tumours: anterior optic pathway compression, followed by oculomotor disorders and pituitary apoplexy.

Orbital exenteration: Institutional review of evolving trends in indications and rehabilitation techniques

PURPOSE

To determine the changes in indications for orbital exenteration over 20 years and to assess its impact on patient survival. Evolving techniques of rehabilitation of the orbit in our institution were also evaluated.

METHODS

This was a retrospective review of hospital records of patients who underwent orbital exenteration from 1995 to 2015 in a tertiary care center. Data extracted included primary location of the tumor, preoperative treatments, interval between initial diagnosis and exenteration, status of surgical margins, presence of metastatic disease, and postoperative survival. The types of prosthesis utilized over the years were also reviewed. Cox regression analysis was performed for categorical variables. Kaplan-Meier analysis was used to estimate post-exenteration survival.

RESULTS

Over a 20-year period, orbital exenteration was performed on 100 orbits of 100 patients. The mean age was 39.4 years (range: 2 months to 90 years). The most common indications among 98 malignant causes were retinoblastoma, squamous cell carcinoma, basal cell carcinoma, extraocular extension of uveal melanoma, and conjunctival melanoma. Postoperative survival was significantly related to age and tumor location but independent from gender, surgical margin, histopathological diagnosis, previous treatment modality, and preoperative interval. In the whole cohort, 1-year and 5-year survival rates were 97% and 84%, respectively.

CONCLUSIONS

Exenteration appears to be life-saving in children with orbital extension of retinoblastoma. While patients exenterated for malignant eyelid tumors have the best chance of survival, those with orbital extension of uveal melanoma and adenoid cystic carcinoma of the lacrimal gland have the worst prognosis.

Future opportunities in diabetic retinopathy research

PURPOSE OF REVIEW

The risk of vision loss from diabetic retinopathy has fallen dramatically over the past 3 decades with improvements in diabetes and blood pressure treatments, and with advances in laser surgery and intraocular drug delivery. Nevertheless, diabetes continues to be a major cause of blindness. This study summarizes the state of the art in diabetic retinopathy research and provides a perspective on opportunities for future investigations.

RECENT FINDINGS

New insights into the pathophysiology of diabetes and diabetic retinopathy will improve metabolic control. Structure-function analyses are revealing new details of diabetic retinopathy. Intraocular drug therapy provides improved visual outcomes. Together these steps will yield better means to detect and quantify vision loss, and to develop patient-specific treatments to preserve vision for persons with diabetes.

SUMMARY

Retinopathy is one of the most successfully treated complications of diabetes and will continue to be an important area of research for patients and their families.

Retinal Imaging: Past, Present, and Future

Summary The field of retinal imaging has grown in leaps and bounds over the past 10 years. As these new technologies allow us to visualize different pathologies and anatomy, it is critical that we take the time to establish a consensus on what is normal, in order to define what is abnormal. We might consider how this technology affects the diagnosis and treatment of eye disorders and diseases, and ultimately, most importantly, the patient.

The Diabetic Retinopathy Screening Workflow: Potential for Smartphone Imaging

Complications of diabetes mellitus, namely diabetic retinopathy and diabetic maculopathy, are the leading cause of blindness in working aged people. Sufferers can avoid blindness if identified early via retinal imaging. Systematic screening of the diabetic population has been shown to greatly reduce the prevalence and incidence of blindness within the population. Many national screening programs have digital fundus photography as their basis. In the past 5 years several techniques and adapters have been developed that allow digital fundus photography to be performed using smartphones. We review recent progress in smartphone-based fundus imaging and discuss its potential for integration into national systematic diabetic retinopathy screening programs. Some systems have produced promising initial results with respect to their agreement with reference standards. However further multisite trialling of such systems' use within implementable screening workflows is required if an evidence base strong enough to affect policy change is to be established. If this were to occur national diabetic retinopathy screening would, for the first time, become possible in low- and middle-income settings where cost and availability of trained eye care personnel are currently key barriers to implementation. As diabetes prevalence and incidence is increasing sharply in these settings, the impact on global blindness could be profound.

[State-of-the-art cataract surgery and intraocular optical correction]

The paper provides current knowledge on cataract epidemiology worldwide and in the Russian Federation, including issues of cataractogenesis and prevention. An overview of medical equipment for preoperative and intraoperative diagnostics is provided. Key aspects of the conventional ultrasonic phacoemulsification method as well as the most marked trends in correction of aphakia with intraocular lenses and in design of the latter are presented. Major laser-assisted techniques, including those that imply the use of femtosecond laser systems, and results that they yielded to date are discussed in detail.

[Fundamental ophthalmology: the role of electrophysiological studies]

Studying of functional aspects of eye disease pathogenesis by electrophysiological methods is widely demanded in fundamental ophthalmology. Introduction of modern methods of functional assessment into experimental and clinical projects significantly broadens knowledge of normal and pathological functioning of the visual system and is the basis for further development of new strategies of pathogenetic treatment, diagnostics and expert evaluation. Some problems of ophthalmology, including those that concern age-related macular degeneration, glaucoma, diabetic retinopathy, and other diseases, are considered in the context of how much electrophysiology contributes to their solution. The role of functional examinations of the retina in studying pathophysiology of neurodegenerative brain diseases, such as Alzheimer's and Parkinson's, is also discussed.

[Keratoconus: modern approaches to pathogenetic studies, diagnosis, optical correction, and treatment]

OBJECTIVE

To evaluate modern approaches to pathogenetic studies, diagnosis, optical correction, and treatment of keratoconus (KC).

MATERIAL AND METHODS

Research results over the recent years obtained with up-to-date methods of pathogenetic studying, diagnosis, correction, and treatment of KC are presented.

RESULTS

Modern approaches to KC consist in analysis of corneal composition and trace elements migration as well as influencing factors. Topographic keratometry and pachymetry proved effective in early detection of KC. Results of intrastromal corneal segments implantation and corneal collagen cross-linking for optical correction and prevention of progression of KC are presented. The use of contact lenses and penetrative keratoplasty for optical correction in KC is comparatively analyzed. A new technique of complete corneal stromoplasty with viscoablation, which does not require anterior corneal stroma pre-separation and removal over the whole area of transplantation and ensures good visual control of Descemet's membrane separation, is suggested. Combined eximer laser photorefractive and phototherapeutic keratectomy for early keratoconus is theoretically substantiated.

CONCLUSION

In most patients the discussed methods ensure prevention of progression of keratoconus, optical correction, and treatment. Prospects of further improvement of early diagnosis and treatment are associated with profound studying of the disease pathogenesis.

Optical coherence tomography in pediatric ophthalmology: current roles and future directions

The application of existing optical coherence tomography (OCT) technology to the pediatric population is limited in both the design specification of the device and its hardware. However, the potential of OCT in the pediatric population has not been fully realized. The authors review the literature, highlighting the currently available spectral-domain OCT technology and summarizing the reported normal pediatric OCT parameters for retinal nerve fiber layer and macular thickness. They also review the pediatric ophthalmological conditions in which OCT has been used and discuss advancements in OCT design and their potential applications to the pediatric population. The use of OCT in pediatric populations is likely to increase greatly in the coming years, aiding clinical decision-making and providing new insights into pediatric disease pathophysiology.

[Therapeutic innovation in AMD and other retinal diseases]

Age-related macular degeneration (AMD) is a leading cause of severe visual impairment in individuals over 50 years in developed countries. Latest advances in imaging techniques have led to improved and accurate diagnosis of AMD. We witness a major breakthrough in the treatment of the neovascular form of AMD with the antiangiogenic (anti-VEGF) drugs. However, no therapy is yet available for the atrophic dry form of AMD. Innovative strategies gene therapy, cell therapy, nanotechnology neuroprotection- and multidisciplinary approaches are emerging to prevent the decline in vision in aging populations and its health implications.

[Screening for visual impairment in children: new tests and the place of the orthoptist]

The fragility and plasticity of visual function in children necessitates early detection and treatment of visual disorders. New approaches such as portable automatic refraction, tonometry and digital fundus examination have improved the quality of screening The problem now is a lack of ophthalmologists. One possible solution is to redefine the role of orthoptists. The waiting time for an ophthalmologist appointment is very long in some parts of France (up to a year), because of a training quota established in the 1980s, as well as retirements (average age 52 years), and a concentration of specialists in the south of France and around medical schools. Today, France trains only 80 specialists per year, whereas twice as many are needed Anglo-Saxon countries (US, Canada, United Kingdom) have created a profession--the optometrist--that is intermediate between the optician and the ophthalmologist. This profession is not recognized in France, yet optometrists are capable of detecting many anomalies and quickly referring a child to a specialist.

Application of new ophthalmic technology in the pediatric patient

PURPOSE OF REVIEW

The present review will summarize briefly the recent advances in diagnostic tools, surgical techniques, and ophthalmic medications as they relate to the pediatric patient. The review will highlight results from studies that have investigated these new technologies and techniques.

RECENT FINDINGS

In the past several years there has been a plethora of literature on the application of new technologies and surgical techniques in children. New tools have been used for everything from gathering normative data about the pediatric eye to using the technologies to study diseases such as glaucoma and ocular tumors. Results of surgical techniques such as small-incision cataract surgery, sutureless vitrectomy, and refractive surgery are now reported with regularity in the pediatric ophthalmology literature.

SUMMARY

In the past 10 years pediatric ophthalmology has made significant advances. Technology has enabled us to qualify and quantify disease states more efficiently, and to explore new surgical techniques for disease processes that were formerly considered relatively untreatable.

Methodologies to diagnose and monitor dry eye disease: report of the Diagnostic Methodology Subcommittee of the International Dry Eye WorkShop (2007)

The role of the Diagnostic Methodology Subcommittee of the Dry Eye Workshop was 1) to identify tests used to screen, diagnose and monitor dry eye disease, 2) to establish criteria for test performance, and 3) to consider the utility of tests in a variety of clinical settings. The committee created a database of tests used to diagnose and monitor dry eye, each compiled by an expert in the field (rapporteur) and presented within a standard template. Development of the templates involved an iterative process between the Chairman of the subcommittee, the rapporteurs, and, at times, an additional group of expert reviewers. This process is ongoing. Each rapporteur was instructed on how to the complete a template, using a proforma template and an example of a completed template. Rapporteurs used the literature and other available sources as the basis for constructing their assigned template. The chairman of the subcommittee modifed the template to produce a standardized version and reviewed it with the rapporteur. The completed database will be searchable by an alphabetical list of test names, as well as by functional groupings, for instance, tests of aqueous dynamics, lipid functions, etc. The templates can be accessed on the website of the Tear Film and Ocular Surface Society (www.tearfilm.org). This report provides a general overview of the criteria applied in the development of tests for screening and diagnosis.

Recent advances in ophthalmic anterior segment imaging: a new era for ophthalmic diagnosis?

Anterior segment imaging is a rapidly advancing field of ophthalmology. New imaging modalities, such as rotating Scheimpflug imaging (Pentacam-Scheimpflug) and anterior segment optical coherence tomography (Visante OCT and Slit-Lamp OCT), have recently become commercially available. These new modalities supplement the more established imaging devices of Orbscan scanning slit topography and ultrasound biomicroscopy (UBM). All devices promise quantitative information and qualitative imaging of the cornea and anterior chamber. They provide a quantitative angle estimation by calculating the angle between the iris surface and the posterior corneal surface. Direct angle visualisation is possible with the OCT devices and UBM; they provide images of the scleral spur, ciliary body, ciliary sulcus and even canal of Schlemm in some eyes. Pentacam-Scheimpflug can measure net corneal power, a feature particularly useful for cataract patients having undergone previous corneal surgery. Anterior segment OCT can measure corneal flap depth following LASIK and anterior chamber width prior to phakic intraocular lens implantation. The arrival of the new imaging devices may herald the dawn of a new era for ophthalmic diagnosis, particularly in view of the ease and non-contact nature of examination.

Advances in Imaging of the Optic Disc and Retinal Nerve Fiber Layer

In the past decade, three technologies for imaging the optic disc and retinal nerve fiber layer have become commercially available: 1) confocal scanning laser tomography with the Heidelberg retinal tomograph; 2) confocal scanning laser polarimetry with the GDx VCC; and 3) optical coherence tomography with the Stratus OCT. Each uses different principles of physics. Understanding the merits and limitations of each of these technologies requires familiarity with the principles of operation of each device. This knowledge should be considered a prerequisite for the appropriate clinical utilization of these devices and for accurate interpretation of their results.

Glaucoma screening: current trends, economic issues, technology, and challenges

PURPOSE OF REVIEW

Glaucoma is one of the leading causes of irreversible blindness worldwide. Early glaucoma detection and treatment are currently the only known methods for preventing blindness and low vision resulting from this frequently asymptomatic disease.

RECENT FINDINGS

New technologies for detecting early glaucomatous damage are important in diagnosing optic nerve disease, not only in community screening settings but also in clinics. Imaging of the optic nerve head and macula and retinal nerve fiber layer analysis can provide quick, automated, and quantitative measurements in agreement with clinical estimates of optic disc structure and visual function. In the area of perimetry, frequency-doubling technology is a promising and feasible mass-screening method with reasonable sensitivity for detecting visual field loss. Central corneal thickness has emerged as a new risk factor for the development and progression of glaucoma, thereby complicating the role of tonometry and measurement of intraocular pressure as screening parameters for glaucoma. Along with technological advances, strides are also being made with public policy and legislative efforts to bring glaucoma onto the national and global health care agenda. These initiatives incorporate vision-screening goals into national disease prevention programs emphasizing the need for early glaucoma detection and treatment.

SUMMARY

Glaucoma awareness needs to be increased through better education, and compliance with follow-up care needs to be improved to decrease the economic and social costs from glaucoma. In addition, screening models need to be developed that will be effective in developing countries where the risk of blindness from glaucoma is highest.

[Current trends in the development of functional studies in ophthalmology]

The paper details the currently available psychophysical and objective diagnostic methods. Among the recently used improvements, there is enhancement of the capacities of a perimetric analysis, an objective control of fixations during multifocal electroretinography, confocal ophthalmoscopy of the retina, and its enhancement coherent optical tomography. Study of local visual activity, quantitative analysis of metamorphopsias, autofluorescence analysis of retinal pigment, and evoked visual multifocal potentials are regarded as innovations. Future developments of methods for functional studies of the organ of vision may follow several directions: improvement of available methods, development and application of new different methods, and estimation of the advantages of different studies.

The future of wavefront sensing and customization

The possibility of achieving supernormal vision in terms of acuity and contrast has fueled the imagination and creativity of vision researchers to pursue the goal of customized wavefront refractive surgery. This goal is achieved by generating an optimal ablation pattern based on individual anatomical and functional characteristics of the treated eye. However, increasing concerns regarding the clinical applicability of customized wavefront correction have emerged, and the possibility of achieving supernormal vision in all patients has been challenged. It is by understanding current optical, physiologic,and technological challenges faced by treating physicians and basic researchers that we can develop clear objectives for the future development of customized refractive surgery.

[Modern diagnostic methods for suspected glaucoma and glaucoma]

BACKGROUND

Diagnosis of early glaucomatous damage as well as the detection of glaucomatous change are still difficult tasks. During the last years numerous new diagnostic techniques have been investigated and some of them have been introduced to the market.

METHODS

This paper reviews the different aims of diagnostic technologies in the field of glaucoma. Methods appearing suitable for a large-scale use by ophthalmologists will be judged according to their suitability to meet the goals of early diagnosis, objective diagnosis, progression analysis and screening.

CONCLUSIONS

The new diagnostic techniques have not yet greatly influenced our diagnostic procedure. This is mainly due to the fact that, for the most difficult borderline cases of glaucoma, these methods are of limited value, or have not yet been sufficiently investigated. Nevertheless, the Heidelberg retina tomograph (HRT), the nerve fiber analyzer GDX, short wavelength perimetry (SWAP), and the frequency doubling test (FDT) may play a role in these cases. For follow-up, HRT and GDx have proven valuable, especially in early stages of the disease. The very short testing time of FDT together with good specificity qualifies this test for glaucoma screening.

Improving Visual Function Diagnostic Metrics With the Use of Higher-order Aberration Information From the Eye

PURPOSE

This paper reviews the currently used visual function diagnostic metrics, acuity, refractive error, and contrast sensitivity, and suggests ways to create new metrics using the information that has recently become available due to advances in measuring the higher-order aberrations of the eye. Particularly, emphasis is placed on finding metrics that address certain aspects of vision rather than on general metrics.

METHODS

Two metrics based on the modulation transfer function are introduced, the Visual Quality Factor (VQF), which is a value based on the modulation transfer function between the spatial frequencies of 3 and 12 cycles per degree (c/deg) giving a measure of the overall degradation of visual quality due to aberrations, and the Subjective Sharpness Factor (SSF), which is a value based on the modulation transfer function between the spatial frequencies of 15 and 40 c/deg, giving a measure of the decrease in perceived image "sharpness" due to aberrations. Two metrics based on the point spread function are suggested, Point Spread Quality (PSQ), which is a measure of the "compactness" of the point spread, and Multiplicity Factor, which is a measure of the multiplicity of perceived images by measuring the number of discrete peaks in the point spread function.

RESULTS

The VQF and SSF values for both monochromatic and polychromatic cases are analyzed with regard to the number of acuity letters lost using data from a published study.

CONCLUSIONS

The SSF is found to be the best overall correlate with acuity performance if the degradation of the letter stimuli is not excessive.

The diagnosis and management of dry eye: a twenty-five-year review

PURPOSE

To review the advances in the diagnosis, pathogenesis, and management of dry eye disease in the past 25 years.

METHODS

Literature review.

RESULTS

The preocular tear film is a hydrated mucus gel that contains soluble antimicrobial proteins and growth factors that protect and support the ocular surface. The final common pathway in dry eye is a perturbation of the integrated ocular surface/lacrimal gland reflex unit. Diagnostic tests evaluating tear composition and clearance appear to show stronger correlation with the severity of ocular irritation symptoms and keratoconjunctivitis sicca (KCS) than the conventional Schirmer tests. KCS is a condition of abnormal differentiation and mucus production by the ocular surface epithelium that results in a poorly lubricated, abnormally permeable ocular surface that has increased susceptibility to environmental insults. Chronic subclinical ocular surface inflammation appears to play a key role in the pathogenesis of KCS. New therapeutic strategies are aimed at reducing the ocular surface inflammation of dry eye disease.

CONCLUSIONS

There has been a tremendous increase in knowledge regarding dry eye disease in the past 25 years that has resulted in improved diagnostic classification and new targeted therapies.

Specular microscopy, confocal microscopy, and ultrasound biomicroscopy: diagnostic tools of the past quarter century

PURPOSE

To identify, characterize, and illustrate the most important past and future potential contributions of specular, confocal, and ultrasound biomicroscopy to clinical diagnosis and research applications in the cornea from the past 25 years.

METHODS

Specular microscopy, in vivo tandem scanning confocal microscopy (TSCM), scanning slit confocal microscopy (SSCM), and high-frequency ultrasound biomicroscopy are examined.

RESULTS AND CONCLUSIONS

This review demonstrates the abilities and limitations of three powerful new in vivo imaging modalities to resolve the cellular and structural layers of the cornea temporally and spatially in three or four dimensions, (x, y, z, t). Clinical pathological processes such as inflammation. infection, wound healing, toxicity, embryonic development, differentiation, and disease, which previously could be studied only under static ex vivo conditions, can now be dynamically evaluated over time. Thus, with continued development and application in vivo, noninvasive microscopic techniques should provide exciting new insights into understanding the structure and function of not only the eye, but also other multicellular organ systems in health and disease. These new imaging paradigms are in the first rank of advances in medical science in the past quarter century.