Chicago Glaucoma Center of Excellence:
Glaucoma is a serious, potentially disabling disorder of the optic nerve related to elevated intraocular pressure (IOP). It generally affects both eyes, although at the time of diagnosis one eye may be more advanced than the other. It can effect all ages, races and ethnic groups, although most glaucoma sufferers are over 40. It is asymptomatic in its early stages: even someone with completely normal vision may have glaucoma.
The optic nerve travels from the eye to the brain and carries over 1,000,000 neurons of vision information. If it is damaged the quality of vision suffers. Visual loss is glaucoma has been described as silent and insidious: the sneak thief of sight. It can profoundly affect one's quality of life.
The optic nerve has a superficial layer called the retinal nerve fiber layer (NFL) and a deeper portion called the optic disk. The optic disk has an inner portion called the cup. The cup is always smaller than the disk and the relative size of one to the other is called the cup disk ratio. The cup disk ratio (C/D) ranges from 0.0 to 0.99. An average cup/disk ratio is 0.1 to 0.5. In general the lower the cup disk ratio the better.
Cup disk ratios over 0.5 are suspicious as is any patient where the cup disk ratio differs by .2 or more between the two eyes, particularly if the eye with the larger cup/disk ratio has a higher intraocular pressure than the fellow eye. To confound our diagnosis of glaucoma there are times when patients with high C/D rations do not have glaucoma and there are individuals with small C/D ratios that nontheless do have glaucoma. Advanced imaging technology can be very helpful and sometimes the only way to sort out these cases.
In its initial stages, there is loss of either or both of the supericial (NFL) or deep portions of the nerve but NO vision loss has yet occured. Frequently, but not always, IOP (intraocular pressure) is elevated during this stage. It is advantageous to detect the glaucoma during this pre-perimetric (no vision loss) phase.
Remember that having a normal intraocular pressure does not mean that you cannot have glaucoma as 25% of patients with glaucoma have normal pressure (normal pressure glaucoma).
If you are worried or concered about glaucoma our center is prepared to fully analyze your eyes and advise you on the proper and prudent course of action! You need not look further--contact us for more information or call us today for your appointment.