Medical vs Surgical Treatment of Glaucoma
The current scenario of medical treatment and glaucoma surgery has changed drastically in the last two decades. There are now multiple effective topical medication (eye drops) for medical management of glaucoma. Some of the eye drops are used only once a day which is quite convenient to the patient.
The surgical options are also many. It is always a matter of dilemma for the patient to decide between using the eye drops for the rest of his or her life or choose the glaucoma surgical options to hopefully not need any medical treatment later.
Guidelines for Taking Eye Drops
Tears continuously are produced in our eyes by structures called lacrimal glands.
These tears form a protective lubricating film covering the surface of the eye and have a volume of 7-10 microliters. In contrast, a single eye drop of a glaucoma treatment medication administered to the eye has a volume of 25-50 microliters. This means that an excess of drug is administered in each drop. Some of this surplus will overflow to the sides of the eye. Do not worry about this. The rest drains through the lacrimal duct. Only 1-7% of the eye medication drop passes through the cornea and enters into the eye. This is sufficient to have the desired effect of lowering interocular pressure.
Approximately 80% of the drug reaching the lacrimal duct is absorbed systemically, meaning that it enters the bloodstream. This is responsible for many of the side effects associated with glaucoma treatment medications administered through an eye drop.
Based on this information, it is essential to understand the following points:
Although it might seem like most of the eye drop streams down your face, enough of it is absorbed through the cornea to be effective.
It is unnecessary to apply a second drop into each eye. One is sufficient. Exceptions to this include if you miss the eye completely with the first drop or if for some reason your eye is shut completely before the drop is applied.
You can limit medication side effects using a procedure called nasolacrimal duct occlusion. This is accomplished by applying slight pressure to the inner canthus of the eye, the region that is closest to the nose.
In the inner canthus, you will encounter a structure that is shaped like a grain of rice. Press it to the bone while applying the eye drop. This serves to block most of the medication from entering the nasolacrimal pathway for absorption into the blood. This will decrease the intensity of systemic side effects that the medicine may cause. It also ensures that more of the medication will stay in the eye for absorption.
What Are the Available Glaucoma Surgery Options?
The patients of open angle type of glaucoma may be advised laser surgery – ALT (argon laser trabeculoplasty) or SLT (selective laser trabeculoplasty). The effect of trabeculoplasty usually does not last long and re-treatment or surgery may be advised later.
The patients of angle closure type of glaucoma benefit from laser peripheral iridotomy and the results are usually good.
The most commonly performed glaucoma surgery is trabeculectomy which is quite effective but the chances of complications are also more.
Non-penetrating glaucoma surgeries also achieve good intraocular pressure (IOP) control. They include:
- Deep sclerectomy (may or may not include a collagen implant)
In the recent years, more devices have been developed for surgical intervention in glaucoma cases. Here are some of the shunts, implants and stents (minimally invasive glaucoma surgeries – MIGS) used in glaucoma surgery:
- Tube shunt implants – Molteno glaucoma implant, Baerveldt glaucoma implant and Ahmed glaucoma valve
- iStent, Glaukos Corp
- CyPass Micro-Stent, Alcon Laboratories
- Xen Gel Stent, Allergan
- InnFocus Micro-Shunt, Transcend Medical
Efficacy of Glaucoma Surgery Over Eye Drops
Currently available medical and surgical treatment options for glaucoma are both effective. The only major difference between them is that there is a hassle of using the eye drops everyday if the patient wants to control IOP only with medical treatment whereas the IOP remains under control after a surgical procedure or a series of procedures.
What Would Be the Ideal Treatment of Glaucoma
The ideal treatment of glaucoma would be a single surgical procedure which permanently keeps the intraocular pressure in a range which does not further cause glaucomatous damage and the disease does not progress.
Unfortunately such a single treatment option is not available presently. To achieve optimal disease control, we need to combine various medical and surgical options. The patient also needs to be in regular follow-up to monitor the optic nerve health and visual field changes.
Why Glaucoma May Progress in Spite of the Treatment
There are some genetic, vascular and structural factors which are involved in the causation of glaucoma. Therefore systemic evaluation of patients of glaucoma is extremely important for complete management of this condition.