Glaucoma is a process of degeneration of optic nerve fibers, which usually occur because of high intraocular pressure which is mostly more than 21 mm Hg. At times there is sudden painless loss of vision. This is an emergency situation.
Glaucoma can be of two types: open angle and angle closure glaucoma.
In open angle glaucoma there is trabecular meshwork fibrosis which causes decreased drainage of aqueous humor which leads to increase in intraocular pressure. Excess production and decreased drainage both are responsible for increased intraocular pressure.
Angle closure glaucoma occurs in case of mid-dilated pupil when the iris get adhere to the lens fibres and blocks the flow of aqueous humor from posterior compartment to anterior compartment. Thus there is increase in intraocular pressure in posterior compartment which pushes the iris forward forming “iris bombe” which get adhered to trabecular meshwork thus end up blocking the meshwork and increasing the pressure.
So open as well as close angle glaucoma major aetiology is increase in intraocular pressure which brings changes in lens fibers and finally deteriorating the vision.
Symptoms include headache and sudden loss of vision. These are two major symptoms with which a patient visits a doctor.
What is the First Sign of Glaucoma?
The first sign which is encountered in medical practice is increase in intraocular pressure which can be detected by a tonometer. Doctor needs to place the tip of tonometer on the eyeball and get exact reading of the pressure changes. A variation of 8 mm Hg suggests of open angle glaucoma whereas, pressure of 5 mm Hg suggests that there is underlying problem. There is usually diurnal variation seen in intraocular pressure. In late stages intraocular pressure increase from 21 mm Hg to 30 mm Hg.
Another finding of glaucoma is anterior segment changes which usually remains normal in open angle glaucoma while in close angle glaucoma there is narrowing of anterior segment.
After a prolonged period of time there are certain disc changes that include changes in optic disc which usually begins with peripheral changes and then moving towards center.
Splinter hemorrhages are seen.
Cup Disc ratio is more than 0.7 suggestive of glaucoma.
NRR thinning is also a prominent feature of glaucoma.
Blood vessels are shifted nasally and thus associated with bayoneting sign or Z appearance at the edge of cup.
Lamellar dot sign is another such finding which is found on lamina cribrosa.
Pulsations may be felt in optic disc.
At time disc edema is even seen along with the hemorrhage.
Inferior and superior – vertical oval cup is seen which is known as Hoyt’s sign. This is associated with NRR atrophy.
Central disc changes are the most common changes witness by a physician in a patient of glaucoma. Deepening of the cup is also seen.
Apart from changes in optic disc there is vision changes associated with glaucoma which includes various patterns.
As the degeneration reaches the maximum level there are chances of total vision loss.
The disease progresses rapidly and thus proper timely management is key step to prevent the disease.
The drugs to be given vary from open angle glaucoma to close angle glaucoma. The drug of choice is beta blockers in open angle glaucoma and for close angle glaucoma the drug of choice is acetazolamide. Accordingly treatment should be planned. In emergency in areas where there is no medications available doctor breaks the adhesion by applying pressure on the eyeball and thus reducing the pressure. These are the most common methods used in rural settings where there is lack of facilities and medications.
Hence glaucoma, which is still considered a cause of blindness in developing countries, should be treated vigorously in order to reduce the incidence of blindness.
- Mayo Clinic. Glaucoma. https://www.mayoclinic.org/diseases-conditions/glaucoma/symptoms-causes/syc-20372839
- American Academy of Ophthalmology. What Is Glaucoma? https://www.aao.org/eye-health/diseases/what-is-glaucoma
- National Eye Institute. Facts About Glaucoma. https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/glaucoma
- WebMD. Glaucoma: Symptoms, Causes, Diagnosis, Treatment. https://www.webmd.com/eye-health/glaucoma-eyes
- Cleveland Clinic. Glaucoma: Types, Causes, Symptoms, Diagnosis and Treatment. https://my.clevelandclinic.org/health/diseases/14415-glaucoma