An Ahmed Valve, or glaucoma drainage valve, is a device that is used to help lower intraocular pressure when maximum medical therapy with eye drops and laser treatment is not enough.
A tube is surgically inserted into the front part of the eye allowing the aqueous fluid from inside the eye to slowly drain through the tube and into the reservoir which is placed on the outside of the eye under the conjunctiva. The fluid is then naturally absorbed by the surrounding tissue.
The slow drainage of fluid decreases the internal eye pressure.
Narrow angles may lead to angle closure glaucoma and laser surgery may lower the risk of developing angle closure.
To assess whether the angles are open or closed and determine if laser surgery is required, an ophthalmologist will perform a comprehensive eye exam. Laser surgery is a relatively safe procedure with small risk for bleeding, inflammation, eye pressure spike or glare.
Compression of the optic chiasm from a pituitary tumor can lead to loss of peripheral vision as retinal ganglion fibres that start in the eye travel down the optic nerve to the chiasm and then finally to the brain. After surgery to remove the tumor, there is less compression on the chiasm and ganglion fibres, so as long as the fibres haven’t been destroyed by the compression they may possibly recover to some extent and your peripheral vision may return but the process will take time.
It sounds as if you have been diagnosed with primary angle closure (PAC) which means the internal drain of your eye is narrowed. This condition is usually picked up during a routine eye exam for glasses or in situations like yours where you have another eye condition that resulted in a thorough eye exam.
In PAC, as you age the drain becomes progressively more narrow and may either suddenly block off resulting in very high eye pressure associated with eye pain, headache, blurred vision and nausea, or slowly close resulting in glaucoma damage to the optic nerve and visual field.
If your doctor feels the drain of your eye is sufficiently narrowed that you are at risk for PAC, you should consider a YAG laser iridotomy.
Lowering the IOP is the best way to slow the course of glaucoma. Because of the advanced nature of your right eye, the lower the pressure, the better.
If drops or laser treatment haven’t lowered the pressure to a target IOP, the next best option is surgery. Losing the remaining 5% due to a post-operative pressure elevation is a rare complication.
If you continue with the drops only, you may eventually lose the remaining 5% due to the high eye pressure.
Prolonged inflammation can happen after any surgery and can be a reason for pain.
Dry eyes can also cause pain, so consider lubricating your eyes with artificial tear drops.
The difficulty reading is due to the dilated pupil which prolonged atropine use can cause. It may take some time for the effect of the atropine to wear off, so you may want to try using reading glasses.
It appears that the glaucoma is advanced in the operative eye and likely the eye pressure was deemed too high hence the need for surgery. It would be important to rule out other ocular conditions such as macular degeneration but vison loss can occur with glaucoma surgery or continue despite surgery.
Glare or a horizontal grey line is an uncommon side effect of YAG laser iridotomy. A recent study showed no difference in glare symptoms before and after laser iridotomy but we have had patients complain of this symptom. Lasering specific locations on the iris is believed to reduce the prevalence of this side effect but recent studies suggest this may not be the case.
It is difficult to comment on glaucoma management for specific cases. Generally, laser is a good option. It may improve your eye pressure and remove the burden of using extra eye drops.
The pressure elevation could be related to poor compliance with glaucoma meds or else just worsening glaucoma. It may also be the underlying mechanism of the glaucoma including Pseudoexfoliation.
Argon laser trabeculoplasty and selective laser trabeculoplast are applied to the trabecular meshwork (drain of the eye) to get it to work better and lower eye pressure in open-angle glaucoma. YAG laser iridotomy makes a small hole in the iris to open access to the drainage area in patients at risk of or who have narrow/closed angle glaucoma.
I don’t foresee any issues with school or swimming as both types of laser surgery are done on an out-patient basis with no prep and quick recovery. The eye is not bandaged and there is minimal downtime.
Unfortunately glaucoma surgery does not always work the first time or in some people. Sometimes though, over time, the pressure may continue to lower so I would not be too concerned yet. Further treatment may include restarting eye drops, revising the existing surgery or doing more surgery.
Gonioscopy is performed during an eye exam to evaluate the internal drainage system of the eye and diagnose narrow-angle glaucoma. We usually recommend treatment for narrow angles when the drain of the eye (trabecular meshwork) is not visible. There is a risk of angle closure glaucoma without treatment. Treatment for narrow angles is a YAG laser iridotomy that makes a small opening in the iris.
Recently, cataract surgery (removal of the natural lens) has been shown to improve narrow angles and the cause for the narrowing is the large lens (cataract) crowding the inside of the eye. If you have minimal cataract or minimal visual issues then laser may be a more conservative approach. In your case, I would ask the optometrist or ophthalmologist to refer you to a glaucoma specialist to confirm if you have a significantly narrow-angle.
If the angle is narrowed, you might need a YAG laser iridotomy prior to SLT to open the angle. Once open, SLT can be used to “clean” the internal trabecular meshwork (TM) of the eye to lower eye pressure. It can be done in any type of glaucoma as long as the angle is open wide enough for angle laser surgery to be performed.
A ghosting or streak of light occurs when light strikes your tear miniscus at the eye lid margin, then goes through the small laser opening. The location of the iridotomy is linked to this side effect. Corneal tattoo is the best option to resolve this. It involves tattooing the cornea over the spot of the iridotomy, so less light can penetrate the small opening.
A certain amount of peripheral (side) vision is needed in order to drive. This may be specific to the jurisdiction you reside in.
Advanced glaucoma causes a restricted visual field. Other eye conditions that may make driving difficult include cataracts, macular degeneration or stroke.
Treatments for glaucoma include eye drops, laser and surgery. Although controlling eye pressure can slow the worsening of glaucoma, there is no cure nor any means of bringing back lost vision.
There is currently no one in southern Ontario who does trabectome surgery. Other surgical options, including iStent and Xen/Aquesys implants, may be available in London and Kitchener.
Recent studies show both ALT (Argon Laser Trabeculoplasty) and SLT (Selective Laser Trabeculoplasty) to be similarly effective. We have been doing ALT for more than 20 years and SLT for about 15. ALT is a more universal laser. SLT is a stand-alone laser without any other application, so it is less available.
Both require applying laser treatment to the internal drain of the eye. The way they work is different. ALT makes a burn mark with shrinkage, opening up the area in between the burn marks to create more drainage. SLT incites inflammation in the drain, recruiting cells to help clean up debris in the drain, so it works better.
Once 360 degrees of the drain is treated with ALT – essentially two treatments – no more can be done. SLT may have more repeatability but this is still controversial. Side effects are the same for both treatments.
The rate of success for a trabeculectomy is 80% at 5 years. Anytime during the post-operative period, the surgery may stop working. Post-op care, with frequent visits to the surgeon, is critical for success.
The rate of complications is less than 2%. Common complications include bleeding, infection, or loss of vision. Long term complications include failure – elevated eye pressure, too low eye pressure, or infection.
An iStent is a small titanium device that can be implanted in the eye’s internal drain to help it drain more. Some glaucoma patients may be candidates for iStents during cataract surgery.
iStents are indicated for early, mild to moderate, open angle glaucoma. They may eliminate one or more glaucoma drugs. Their main limitations are cost and the lack of long-term studies.
It is not uncommon for vision to be blurry for 8 to 10 weeks after surgery, especially if you are still taking steroid eye drops such as prednisolone or Maxidex.
Also if your eye pressure is a little on the low side that can cause the blurry vision.
Once the lens of the eye is replaced after cataract surgery, it is rarely ever replaced again. Later on you may benefit from a YAG Capsulotomy laser to polish the lens.
There is no such thing as normal pressure.
To treat glaucoma, doctors set individualized targets where they hope no further glaucoma damage to the optic nerve or visual field will occur. The more glaucoma damage, the lower the target.
Talk to your mother’s doctor for a referral to a surgeon doing iStents. Your mother needs to be evaluated to see if she is a candidate for the surgery. The evaluation will examine the status of the internal eye drain, whether it is open or closed, and the amount of glaucoma present – mild, moderate, severe.
iStent is a new procedure with no proven track record beyond two years. It may eliminate the need for some eye drops. iStent works best in mild to moderate glaucoma.
It is best to combine iStent insertion with cataract surgery. The biggest issue is the cost of $500/stent. OHIP does not cover this cost so it may not be available in some hospitals and there may be patient pay models.
Some patients may be candidates for iStent during cataract surgery. It is indicated for early, mild to moderate glaucoma and may eliminate one or more glaucoma medications. Its main limitations are cost and lack of long term studies.
If eye drops are working well to control your eye pressure, I would not recommend surgery at this point.
If your ophthalmologist is concerned about your eye pressure or you are having side effects from your present medications, then surgery may be an alternative treatment. Its effectiveness is the same as adding another eye drop, but it doesn’t always work or its effect may not last.
Avoid smoking marijuana. It lowers eye pressure but only for a short period of time. You would have to constantly smoke in order to keep your eye pressure low and then the health risks, especially of lung cancer, are great. Smoking marijuana post surgery can jeopardize the surgical outcome — you may be at higher risk of failure due to scarring.
After laser treatment, make sure you understand and follow your doctor’s instructions for using eye drops. Recovery time after a trabeculectomy can be six to eight weeks or longer. During recovery, you should avoid any bending, heavy lifting, or strenuous physical activity. Also avoid swimming until your doctor advises that you can.
The standard glaucoma surgery is a trabeculectomy with Mitimycin C. It’s a 45 minute procedure with recovery of about 6 to 8 weeks.
Benefits of surgery are lower eye pressure, less eye pressure variability and possible discontinuation of eye drops. Risks include bleeding, loss of vision, infection and failure of about 20% over 5 years.
Some newer operations are less invasive with faster recovery (Trabectome, iStent, Canaloplasty) but they do not lower eye pressure as well as trabeculectomy, so patients may still need to take eye drops or may need more surgery.
It is uncommon to need a second surgery so quickly after a trabeculectomy which lowers eye pressure by making a window on the eye to bypass the eye’s internal drain. After surgery this window may be “too open” or “too closed” resulting in very low or very high eye pressure. If this persists, another surgery may be required to correct this.
It is uncommon for freezing (topical anaesthesia) not to fully take. However, in some patients topical anaesthetics don’t work that well. This may be because the eye is hypersensitized from medications or previous surgeries. Also eyes that tear excessively may wash out the anaesthetic drops.
An injection around the eye is sometimes necessary to control any discomfort, and for surgery, a general anaesthetic may be better.
Glaucoma runs in families with highest risk when parents or siblings have it. If it’s in the extended family, the overall risk of getting glaucoma is low. It can skip generations.
LASIK thins the cornea. Your doctor may underestimate eye pressure in a thinner cornea and miss a glaucoma diagnosis. To get a specific correction factor for eye pressure for the future, get a series of eye pressures measured over the course of the day before and after LASIK.
Because it can be difficult for patients to use multiple eye drop medications and because of less damaging side effects with current laser treatment, we are using laser treatment earlier.
Selective Laser Trabeculoplasty (SLT) has a pressure lowering effect of about 20% – comparable to adding another medication. Laser however, is not a “cure” for glaucoma – it doesn’t always work, its effect may not last, and your ophthalmologist must still continue to monitor your eye pressure.
The surgery of choice for glaucoma is a trabeculectomy. This procedure has been used for more than 30 years and has a proven track record. Recently, a study has shown that a tube shunt operation (Seton) has similar efficacy to the trabeculectomy and possibly less side effects. The tube shunt was traditionally reserved for complicated glaucoma cases or cases that had previously failed a trabeculectomy.
The eye is made up of sophisticated nerve cells that are an extension of the brain and are incapable of regenerating when they are damaged. Currently, we are only able to regenerate certain neural cells in laboratory conditions. We are looking at medications that may help damaged cells survive longer or prevent the damage altogether.
Generally, we don’t give a sedative for a laser procedure. We need the patient to be co-operative and not move. With a sedative, you may become drowsy and your head may fall back from the laser causing injury. Talk it over with your surgeon.
The recovery process for a trabeculectomy is about eight to ten weeks. (There really is no “healing” process involved as “healing” would indicate that the operation has stopped working and wasn’t a success.)
Age can affect recovery. Younger patients tend to recover faster than older patients. Other issues such as previous eye medication use, quantity of medications and duration of use, and smoking can also affect recovery rates.
Usually, a second surgery in the short term after trabeculectomy is not necessary. Your ophthalmologist may, however, need to cut a stitch or “needle” the surgery site to keep it functioning.