Glaucoma is one of the most common causes of loss of vision and blindness. It is known as the ‘silent thief of sight’ because damage occurs slowly and painlessly over many years and, without proper care, it is often not diagnosed until loss of vision is quite advanced. The disease is often missed because peripheral vision slowly fades in different areas in each eye and central vision is not affected until very late in the disease. This causes a narrowing of the vision, known as 'tunnel vision'. It is a disease that can cause complete blindness, yet a person suffering from this would not be aware of it for decades, only realising in the last few years of the disease that there are increasing areas of dimming vision in the periphery closing in on central vision. Therefore, it is crucial that people at risk are identified early and monitored over time, even though they have no symptoms or awareness of the disease.
Because the disease can be difficult to diagnose, it can be hard to differentiate someone with early glaucoma from someone who does not have the disease. Additionally, while most people are aware that glaucoma is related to eye pressure, there are many different forms of glaucoma. Some people can have high eye pressure but not have the disease, yet others have normal or even low pressure and have advanced glaucoma. Each type of glaucoma requires a different approach rather than just the use of pressure-lowering drops. If not identified early and monitored adequately, the mere prescription of eye drops may result in continuing vision loss, despite what appears to be good control of eye pressure.
Diagnosis of glaucoma
Glaucoma specialists are medically trained eye specialists who are further trained specifically in glaucoma, to:
identify risk factors (which increase your chance of getting the disease),
monitor signs (which includes not just eye pressure, but also a number of other factors),
analyse specialised test results,
differentiate between the different causes of glaucoma,
begin appropriate treatment at the correct time and
step up levels of treatment when signs of progression mean the disease is likely to affect your vision significantly in your lifetime.
Because glaucoma is slow to develop, signs of the disease are not obvious in the early stages. As such, many people with signs of early disease or who are recognised as having the risk of developing it, are monitored without active treatment for many months to years.
Correct treatment that is begun early can slow the disease down and reduce the risk of tunnel vision or even blindness. Treatment of glaucoma is aimed at reducing eye pressure and can be separated into 3 groups:
Eye drops for glaucoma
Eye drops which reduce pressure can be used to control the disease and have been highly successful. There are several different classes of eye drops which act in different ways. Some reduce production of aqueous (the fluid inside the eye), others increase drainage of aqueous through different channels and some do both. Glaucoma eye drops generally are very successful and can control the disease in the majority of cases. Sometimes drops are not adequate and, even if they seem adequate, continuing monitoring of the eye pressure and other signs is crucial as glaucoma can still get worse despite apparently good pressure control.
There is new evidence that suggests that eye drops are not the best form of treatment to use first in glaucoma and that laser may be a better and more cost-effective option in the long run.
Laser treatment can prevent glaucoma, delay the development of the disease, enhance control and can often, if used early in the disease, can reduce or sometimes eliminate the need for drops. Different forms of laser are used in glaucoma depending on the cause.
Open Angle Glaucoma - Selective Laser Trabeculoplasty (SLT)
In Open Angle Glaucoma, Selective Laser Trabeculoplasty (SLT) is used to improve control.
SLT is an innovative, non-invasive laser treatment for glaucoma. This quick and simple procedure may be an option for most patients, but is especially suited for patients who cannot tolerate or are unable to self-administer glaucoma medications.
Highly effective, SLT is used as primary treatment for early stages of open angle glaucoma, and can also be used in combination with drug therapy or as an alternative therapy when drugs fail. It is also a flexible treatment option, given that it can be repeated, if necessary, depending on the individual patient’s response.
SLT uses the principle of photoregeneration: the SLT laser applies short pulses of low-energy light to prompt a photo-regenerative response in the trabecular meshwork of the eye, which leads to lowered intraocular pressure. Gentle, non-invasive and repeatable, SLT promotes cellular regeneration without the burn and tissue scarring associated with other conventional laser procedures for glaucoma. Good candidates for SLT include primary-open angle, normal tension, pseudoexfoliation, or pigmentary glaucoma patients who:
Wish to use SLT as a primary glaucoma treatment
Find it challenging to take glaucoma medications due to time or financial constraints, non-compliance and quality-of-life issues
Are currently undergoing drug therapy and need to further reduce IOP without adding drugs
Wish to keep the number of drugs to a minimum
Do not tolerate drugs due to their adverse effects
Experience loss of the pressure-lowering effects of drug therapy
Have had Argon Laser Trabeculoplasty that has failed
Recently, a large research trial from the internationally respected Moorfields Eye Hospital has shown that SLT may be considered as a first-line treatment for people diagnosed with open angle glaucoma as it is better at lowering pressure than eye drops and more cost effective. Published in The Lancet, the results of the LiGHT trial compared the use of SLT versus eye drops as a first-line treatment for treatment-naïve patients who had open angle glaucoma or ocular hypertension.
STUDY NUMBERS / IOP REDUCTION: 718 patients (1,235 eyes). Intraocular pressure (IOP) reduction was similar for those treated with SLT (356 patients, 613 eyes) and medication (362 patients, 622 eyes) after 36-months follow-up.
EYE DROP USE: 78.2% of SLT patients did not need drops to maintain target IOP at 36-months. Further, patients who received SLT were within IOP target for more visits compared with medicated group (93.0% vs 91.3%).
NO SURGERY REQUIRED: No patients who received SLT required surgery to lower IOP, versus 11 eye drop patients.
ADVERSE EVENTS:There were 5 times less medication-drop related adverse events* with SLT (30) compared to eye drops (150).
COST PER PATIENT: The average cost per patient for all ophthalmology expenses was significantly less in the SLT group compared to eye drops (p<0.001)
CONCLUSION: The data supports a change in clinical practice; primary SLT is a cost-effective alternative to drops that can be offered to patients with POAG or ocular hypertension needing treatment to lower intraocular pressure. *Aesthetic side effects or ocular allergic reactions
Read the LiGHT Trial report below:
To read this report in The Lancet, click the link below:
Narrow Angle Glaucoma (NAG) or Angle Closure Glaucoma (ACG) happens when the angle between the iris and the cornea is narrow enough to cause a blockage to the drainage of fluid out of the eye. This results in a high pressure which can occur suddenly (Acute NAG/ACG) or slowly (Chronic NAG/ ACG).
To treat or prevent Acute/ Chronic NAG/ ACG, Laser Peripheral Iridotomy (LPI) is performed:
Although rare, Acute Angle Closure Glaucoma is seen in people who have angle closure (or narrow angles) which has not been previously diagnosed and treated. These people develop extremely high eye pressure which is intensely painful (often in one, but occasionally in both eyes), to the extent that the patient becomes nauseous and often has bouts of vomiting. This is an eye emergency, which if left untreated, can cause severe permanent loss of vision or even total blindness.
Surgery may be required when the disease is severe and cannot be controlled adequately with drops or laser. There are presently two major categories of surgery for glaucoma.
Traditional glaucoma surgery consists of a number of procedures that are very effective in controlling the disease. However, these procedures are major operations and, while they have high success rates and often result in excellent long term control of glaucoma, they are usually recommended when all other measures have failed. One type of traditional glaucoma surgery is Trabeculectomy
MIGS - Minimally (or Micro) Invasive Glaucoma Surgery
Minimally or Micro Invasive Glaucoma Surgery (MIGS) is a completely new class of surgery that has been steadily developing over the last 10-15 years. It has been widely available in Australia since 2016 and Dr Lee is one of the pioneering glaucoma specialists to provide the benefit of these implants, since their introduction. MIGS is an alternative to standard glaucoma surgery and is performed through tiny incisions, causes less trauma to the eye and involves much less 'down time', yet has been proven to be highly effective in controlling the disease. This surgery results in a substantial reduction in eye pressure, reduces and, in many cases, stops the need for glaucoma eye drops. While traditional glaucoma surgery has always been reserved as a last resort, the greatly reduced risk, increased safety, short surgery times and rapid recovery periods means that MIGS can be used earlier in the disease to improve control, compared to traditional glaucoma surgery.
At present, there are 3 different MIGS procedures which are approved for use by the FDA in the United States and by the TGA (Therapeutic Goods Administration) in Australia, although several more are on the way.
All of these procedures at present involve the use of stents, or tiny tubes, to bypass the blockage of the eye's natural drains
In mild glaucoma, the iStent (the world's smallest medical implant) is a titanium implant that is used to bypass the blocked trabecular meshwork (like a funnel being pushed through the grate on top of a drain). Dr Vincent Lee was one of the first Australian glaucoma specialists to implant the iStent after they were introduced to Australia in 2016:
The Hydrus Microstent is a MIGS stent made of a super-elastic, biocompatible alloy (nitinol) that has been used in over 1 million implants to date. It is an intracanalicular scaffold - a type of support structure inserted into the primary fluid canal (known as Schlemms canal) to allow blocked fluid to flow more freely, therefore reducing eye pressure. It is often used in moderate glaucoma. The Hydrus microstent can be described under the category of MIGS procedures known as canaloplasty, in which the primary drainage canal inside the eye is improved in its function.
Dr Lee implanted the first Hydrus Microstent in Victoria in October 2018.
The investigational video below shows how the implant works and how it is inserted into the eye's natural drain (note that the implant is now FDA and TGA approved).:
In more severe glaucoma, the Xen Gel Stent is a tiny porcine gel tube that is passed from inside the eye to the outside through the wall of the eye, under the skin of the eye, beneath the eyelid. The first Xen Gel Stent was implanted in regional Victoria by Dr Lee upon its introduction in April 2018. The procedure is demonstrated in the following video: