This study will assess the value of improved magnetic resonance imaging (MRI) techniques to
study the lens of the human eye. Knowledge of how cataracts develop and progress has been
hampered by the lack of human tissue available for study; MRI may provide an effective means
for learning more about this eye disease.
Normal volunteers between 18 and 70 years of age may be eligible for this study.
Participants will undergo a medical history and complete eye examination, including vision
assessment, eye pressure measurement, lens and retina examinations, and photography of the
MRI scans will be scheduled for a second visit. For this procedure, the volunteer's pupils
are dilated and he or she then lies on a stretcher that is moved into a cylinder containing
a magnetic field. A device similar to a welder's helmet is placed on the head. Attached to
the device are an imaging probe and a small blinking light. The probe receives radio
signals from the eye that a computer converts into images. During imaging, the participant
gazes at the blinking light; this helps keep the eyes from blinking and wandering. Scan
times vary from 2 to 10 minutes; the total time for the study is less than an hour.
Studies of human diabetic cataract and age related cataract formation have been hampered by
unavailability of human tissues especially in the early stages of the disease. Eye bank
tissues are first used for cornea transplants so that by the time they become available for
basic research studies, the lens is no longer suitable for biochemical nor histological
studies. Cataracts usually only become available after extraction which is at the end stage
of their development. However, appropriate surgical lens specimens are no longer available
because cataracts are generally extracted by the destructive phakoemulsification technique.
Therefore, noninvasive techniques are required in order to study the lens in vivo.
Must be between 18 and 70 years of age of either sex.
Must not have uveitis, glaucoma, or be at risk for an adverse reaction to dilation or have
a history of allergic reaction to one of lthe dilating agents to be used.
Must not have any metallic prosthesis, cardiac pacemakers, neural pacemakers, surgical
clips in the brain or on blood vessels, surgically implanted metal plates, screws or pins,
cochlear implants or metal objects in the body especially in the eye.