A new vision for age-related macular degeneration

Pupillometric Characteristics in Patients with Choroidal Neovascularization Due to Age-Related Macular Degeneration

Purpose

To study the pupillary light reflex in patients with choroidal neovascularization due to age-related macular degeneration (AMD).

Methods

The study included 15 patients with AMD and 15 control subjects. A full recording of the pupil's reaction to light was registered and the following eight parameters were measured and reported: baseline pupil radius (R1), latency (T1), minimum pupil radius (R2), amplitude (AMP), maximum constriction velocity (VCmax), maximum constriction acceleration (AC-max), time for maximum velocity (T2), and time for maximum constriction (T3).

Results

All variables measured presented alterations in the AMD group and a number of them were significantly reduced in the AMD group.

Conclusions

The presence of neovascular AMD significantly affects the pupil's response to light stimulus when compared to normal subjects.

Steroid-induced ocular hypertension/glaucoma: Focus on pharmacogenomics and implications for precision medicine

Elevation of intraocular pressure (IOP) due to therapeutic use of glucocorticoids is called steroid-induced ocular hypertension (SIOH); this can lead to steroid-induced glaucoma (SIG). Glucocorticoids initiate signaling cascades ultimately affecting expression of hundreds of genes; this provides the potential for a highly personalized pharmacological response. Studies attempting to define genetic risk factors were undertaken early in the history of glucocorticoid use, however scientific tools available at that time were limited and progress stalled. In contrast, significant advances were made over the ensuing years in defining disease pathophysiology. As the genomics age emerged, it appeared the time was right to renew investigation into genetics. Pharmacogenomics is an unbiased discovery approach, not requiring an underlying hypothesis, and provides a way to pinpoint clinically significant genes and pathways that could not have been discovered any other way. Results of the first genome-wide association study to identify polymorphisms associated with SIOH, and follow-up on two novel genes linked to the disorder, GPR158 and HCG22, is discussed in the second half of the article. However, knowledge of genetic variants determining response to steroids in the eye also has value in its own right as a predictive and diagnostic tool. This article concludes with a discussion of how the Precision Medicine Initiative®, announced by U.S. President Obama in his 2015 State of the Union address, is beginning to touch the practice of ophthalmology. It is argued that SIOH/SIG may provide one of the next opportunities for effective application of precision medicine.

Exploring the potential benefits of vaccinia virus complement control protein in controlling complement activation in pathogenesis of the central nervous system diseases

Aging is a major risk factor for the development of diseases related to the central nervous system (CNS), such as Alzheimer's disease (AD) and age-related macular degeneration (AMD). In both cases, linkage studies and genome-wide association studies found strong links with complement regulatory genes and disease risk. In AD, both CLU and CR1 genes were implicated in the late-onset form of the disease. In AMD, polymorphisms in CFH, CFB and C2 were similarly implicated. The cost of caring for patients with AD or AMD is approaching billions of dollars, and with the baby boomers reaching their 60's, this amount is likely to increase further. Intervention using complement inhibitors for individuals in their early 50s who are at a higher risk of disease development, (testing positive for genetic risk factors), could slow the progression of AD or AMD and possibly prevent the severity of late stage symptoms. Although we have used the vaccinia virus complement control protein (VCP) to elucidate the role of complement in CNS diseases, it has merely been an investigational tool but not the only possible potential therapeutic agent.

CR2-mediated targeting of complement inhibitors: bench-to-bedside using a novel strategy for site-specific complement modulation

Recent approval of the first human complement pathway-directed therapeutics, along with high-profile genetic association studies, has catalyzed renewed biopharmaceutical interest in developing drugs that modulate the complement system. Substantial challenges remain, however, that must be overcome before widespread application of complement inhibitors in inflammatory and autoimmune diseases becomes possible. Among these challenges are the following: (1) defining the complement pathways and effector mechanisms that cause tissue injury in humans and determining whether the relative importance of each varies by disease, (2) blocking or modulating, using traditional small molecule or biologic approaches, the function of complement proteins whose circulating levels are very high and whose turnover rates are relatively rapid, especially in the setting of acute and chronic autoimmune diseases, and (3) avoiding infectious complications or impairment of other important physiological functions of complement when using systemically active complement-blocking agents. This chapter will review data that address these challenges to therapeutic development, with a focus on the development of a novel strategy of blocking specific complement pathways by targeting inhibitors using a recombinant portion of the human complement receptor type 2 (CR2/CD21) which specifically targets to sites of local complement C3 activation where C3 fragments are covalently fixed. Recently, the first of these CR2-targeted proteins has entered human phase I studies in the human disease paroxysmal nocturnal hemoglobinuria. The results of murine translational studies using CR2-targeted inhibitors strongly suggest that a guiding principle going forward in complement therapeutic development may well be to focus on developing strategies to modulate the pathway as precisely as possible by physically localizing therapeutic inhibitory effects.

Age-related macular degeneration: genetic and clinical findings

Age-related macular degeneration (AMD) is a sight threatening eye disease that affects millions of humans over the age of 65 years. It is considered to be the major cause of irreversible blindness in the elderly population in the developed world. The disease is prevalent in Europe and the United States, which has a large number of individuals of European descent. AMD is characterized by a progressive loss of central vision attributable to degenerative and neovascular changes that occur in the interface between the neural retina and the underlying choroid. This location contains the retinal photoreceptors, the retinal pigmented epithelium, a basement membrane complex known as Bruch's membrane and a network of choroidal capillaries. AMD is increasingly recognized as a complex genetic disorder where one or more genes contribute to an individual's susceptibility to development of the condition, while the prevailing view is that the disease stems from the interaction of multiple genetic and environmental factors. Although it has been proposed that a threshold event occurs during normal aging, the sequelae of biochemical, cellular, and molecular events leading to AMD are not fully understood. Here, we review the clinical aspects of AMD and summarize the genes which have been reported to have a positive association with the disease.