What is Glaucoma?
Glaucoma is a medical condition where the optic nerve in the back of the eye becomes damaged usually from elevated eye pressures. The optic nerve acts as a cable transmitting images from the eyeball to the brain. Glaucoma is the second leading cause of blindness worldwide behind cataracts. Not just one condition, it is a group of conditions with a common endpoint of optic nerve damage and side vision loss. When detected early, it can be treated with the hope of maintaining whatever vision is left at the time of diagnosis. Unfortunately, for many patients, they are asymptomatic until they have severe damage. When detected at a late stage, one is often left with tunnel vision and eventually no vision. Risk factors for glaucoma include older age, African American race, and family history.
How Do You Diagnose Glaucoma?
Glaucoma detection involves getting your eyes examined on a regular basis. During a comprehensive eye examination, eye pressures and optic nerves are checked. If eye pressures are abnormally high or the optic nerves have a suspicious appearance suggestive for glaucoma, further testing is performed. These include checking central corneal thickness (the thickness of the windshield of the eye), visual fields (to check for side vision loss), optic nerve imaging (to detect loss/thinning of optic nerve tissue/structures), optic nerve photographs (for future comparison), and gonioscopy (looking at the internal drainage angle to determine if access to it is narrow). If there are abnormalities on the visual field, optic nerve imaging, or both, these usually indicate optic nerve damage and glaucoma. Treatment is then instituted to slow down or prevent further damage and to maintain whatever side vision is left.
Treatments for Glaucoma?
Medications for glaucoma treatment are usually aimed at lowering the eye pressures by decreasing the aqueous fluid made by the eye, increasing the drainage/outflow of aqueous, or both. Different classes of glaucoma medications may be used together to optimize control of glaucoma. Most glaucoma medications are eye drops although there are a couple that are oral pills.
Lasers are performed if there are narrow drainage angles present (laser peripheral iridotomy), to stimulate an increase in the outflow of aqueous fluid from the eye (laser trabeculoplasty), or to decrease aqueous fluid production in an eye with poor visual potential (cyclophotocoagulation).
Laser peripheral iridotomies (LPI) make a small hole in the iris (the colored part of the eye) peripherally to physically open up access to the drainage angle when patients have narrow drainage angles. It is usually a preventative procedure to make it safer for individuals with narrow angles to take medications that can secondarily dilate them: antihistamines, decongestants, antidepressants, etc. If a patient has an acute narrow angle glaucoma attack, the LPI becomes an emergent procedure. Signs and symptoms of an angle closure attack are a combination of eye pain, a bad headache, nausea, vomiting, blurred vision, bloodshot eye, and a mid-dilated pupil.
Laser trabeculoplasties (LTP) are performed to stimulate more drainage from the internal drainage system of the eye (the trabecular meshwork). This is done if a patient is intolerant of glaucoma eye drops or needs to augment medical treatment if still uncontrolled with glaucoma eye drops alone. LTP does not work in every glaucoma patient and when it does work, it does not last forever.
Cyclophotocoagulation (CPC) utilizes a laser probe to treat the ciliary bodies in the eye which make the aqueous fluid to decrease production. It is usually reserved for eyes with poor visual potential and is a procedure of last resort.
Incisional Glaucoma Surgeries
Incisional glaucoma surgeries include i-Stent, trabeculectomies with antifibrotics, and glaucoma drainage devices/tube shunts.
I-Stent is a MIGS (microincisional glaucoma surgery) performed in conjunction with cataract surgery. It is indicated for cases of early to moderate glaucoma and involves inserting the i-Stent (snorkel) into the trabecular meshwork (the internal drainage system of the eye) to allow more aqueous fluid outflow.
Trabeculectomies with antifibrotics is usually the first incisional glaucoma surgery performed for severe uncontrolled glaucoma. It uses the eye’s natural tissues to make another pathway for the aqueous fluid to leave the eye to decrease the eye pressures. Antiscarring medication is used during surgery. Postoperatively, antiscarring injections are given the first 2-3 weeks and a laser is used to melt the sutures in the trap door to help manipulate the success of the surgery. If the trap door scars down, the surgery has failed, and a patient is back on glaucoma eye drops.
If there is excessive inflammation, scarring, or a previous failed trabeculectomy, then a glaucoma drainage device/tube shunt is indicated. A small tube is inserted into the front of the eye and tracks back to a plate that is sutured posteriorly between the eye muscles. Aqueous fluid drains through the tube to the plate.
Not uncommonly, it does take a combination of glaucoma surgeries and glaucoma eye drops to maintain control of a patient’s glaucoma. The key to adequate treatment is timely follow-up and compliance with treatment regimen of glaucoma medications. Regular follow-up is necessary to make adjustments to optimize glaucoma treatment. Prevention is key. By seeing an ophthalmologist annually for general eye health, individuals who are at higher risk of developing glaucoma are identified and appropriately tested to determine if the condition is present or not hopefully at an early stage.