2003 — 2006 |
Glasser, Adrian |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Accommodative Changes in Aging Eyes
DESCRIPTION (provided by applicant): Presbyopia, the age related loss of accommodation, affects everyone by about age 50. The impact of presbyopia on society is considerable from an economic and a quality of life standpoint. Although presbyopia is classically attributed to sclerosis of the lens, the precise causes remain unclear. Studies on humans and monkeys show age changes in both the crystalline lens and the extralenticular accommodative apparatus. No widely accepted cures or preventions for presbyopia currently exist, although the possibility of restoring accommodation using surgical procedures or intraocular accommodative lenses is under investigation. This application proposes 1) using central stimulation of the Edinger-Westphal (EW) nucleus of the brain in rhesus monkeys together with dynamic analyses to better understand how the young monkey eye undergoes accommodative optical changes, 2) to use in vitro mechanical stretching of monkey lenses to study the accommodative optical changes and to understand if these are similar to those that occur in vivo with natural accommodation and 3) to determine if and how the dynamic and accommodative optical performance of the monkey eye changes with age as rhesus monkeys develop presbyopia. Two experimental approaches will be used; 1) accommodative optical and geometric changes in the lens will be measured dynamically during EW stimulated accommodation in anesthetized monkeys. The dynamic accommodative responses will be compared in "young" and "middle-aged" monkeys. 2) In vitro mechanical stretching experiments will be performed on partially dissected enucleated monkey eyes to artificially induce accommodative changes in the lens. The mechanically induced optical and geometric changes will be compared with those that occur during accommodation in vivo and as a function of age. The results will quantify the dynamic accommodative responses in monkey eyes to understand the dynamics of accommodation, will allow a determination of the differences and similarities in the accommodative changes between in vitro mechanical stretching and in vivo accommodation of the lens and on how the accommodative performance of the monkey lens changes with age. The goal of this research is to gain a better understanding of how the monkey lens undergoes physical and optical accommodative changes and contribute to the progression of presbyopia. This research will provide a foundation for studies directed at understanding if accommodation can be restored with artificial accommodative intraocular lenses.
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2008 — 2010 |
Glasser, Adrian |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Clinical Accommodation Measurement
[unreadable] DESCRIPTION (provided by applicant): There is considerable interest in understanding if accommodation can be restored to the presbyopic eye. The first so called accommodative intraocular lens received United States Food and Drug Administration (FDA) approval in November 2003, and FDA clinical trials are currently underway for scleral expansion bands, another other so-called "accommodation restoration" surgical procedure. Several new, potentially accommodative intraocular lenses are undergoing research and clinical testing and FDA clinical trials are likely to commence for some of these devices within the next two years. Objective accommodation measurement has largely been left to scientists interested in accommodation. Few clinicians use objective means to measure accommodation. No clinical, objective, accommodation testing protocols have been developed, tested or validated for testing pseudophakic eyes. Many commercially available autorefractors, wavefront aberrometers and ocular biometric instruments are on the market and being used in clinical practice, but few if any of these instruments have been systematically tested and validated for objective accommodation measurement. Despite the FDA approval of the first accommodative intraocular lens, it still remains unclear if accommodation is or can be restored with intraocular lenses. This application aims to: (1) design, develop and test clinical accommodation testing protocols using commercially available, objective clinical instruments that can be used in a clinical setting and to test the efficacy of the instrumentation and protocols on normal, young human subjects; (2) test the efficacy of these protocols and instruments in normal, older pre-presbyopic and presbyopic subjects, the target population of accommodation restoration procedures, who have low accommodative amplitudes, to determine the efficacy of the protocol and instrumentation to measure the low accommodative amplitudes expected in this population; (3) to determine the ability of the instruments and the efficacy of the protocols to measure accommodation in pseudophakic eyes and (4) to implement these protocols and instruments in clinical accommodation testing to determine if and how well accommodation restoration procedures such as scleral expansion, radial sclerotomy or accommodative intraocular lenses may restore accommodation in presbyopes. The long term objectives are to validate a commercially available autorefractor, aberrometer and biometry instrument, to demonstrate that accommodation can be measured objectively in clinical settings, to encourage objective accommodation measurement to become widely accepted and implemented in clinical practice and clinical trials to aid in and foster the development of safe and effective accommodation restoration concepts. PUBLIC HEALTH RELEVANCE: A variety of surgical procedures and accommodative intraocular lenses are being developed in an effort to restore active accommodation to the presbyopic eye. Surgical procedures are not without risks. This application proposes the development and testing of objective accommodation measurement protocols in an effort to establish the efficacy of the accommodation restoration surgical procedures so that the benefits can be clearly established to be weighed against the risks. [unreadable] [unreadable] [unreadable]
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