Surgery Risks and Benefits

Surgery Risks and Benefits
Chat from June 20, 2012
Guest Speaker – Dr. Anand Mantravadi
Steven Beck, Editor
Lorraine Miller, Editor, Chat Topic Researcher

Moderator
Tonight’s topic is “Surgery Risks and Benefits.”  Doctor, if surgery is required on both eyes, how is the determination made as to which eye is operated first?

Dr. Anand Mantravadi
Great question!  In general, there are two approaches to this and the decision making can be complex.  If one eye from a glaucoma standpoint is less severe, we would generally recommend operating on the more severely affected eye first.  It can be tough; however, if one eye has very limited visual potential and the other eye has good visual potential, and both eyes need surgery quickly. In this scenario, operating on the worse eye, may delay treatment to the better eye.  There are many pros and cons to both approaches. 

P
Can a patient do anything to maximize the benefits of surgery or is success out of their control?

Dr. Anand Mantravadi
Surgical success can depend on many factors, some that we have control over, and some that we don’t. From a patient standpoint, close adherence to the post-operative recommended regimen by your surgeon can indeed enhance success rates.

P
Is vision improvement after surgery common?

Dr. Anand Mantravadi
After glaucoma surgery, specifically, visual acuity will generally return to within one line of preoperative visual acuity after the eye has stabilized during the post operative period. It is not uncommon to have more blurry vision immediately following surgery for a while until things stabilize.

P
If cataracts develop due to glaucoma surgery, how quickly do they occur?

Dr. Anand Mantravadi
Generally, it is a pretty gradual occurrence.

P
Is dry eye a risk for glaucoma surgery?

Dr. Anand Mantravadi
The health of the ocular surface can indeed play a role in some glaucoma surgeries such as trabeculectomies. Severe dry eye may pose some potential issues with glaucoma surgery.  However, sometimes pre-existing dry eye, is often exacerbated with topical glaucoma drops and if glaucoma surgery is successful in minimizing topical glaucoma medications, it may actually get better.

P

Which surgery has the greatest risk of bleeding?

Dr. Anand Mantravadi
All glaucoma surgeries have a small risk of bleeding, that is, slightly higher in those on chronic anticoagulation therapy such as Coumadin, Plavix, or aspirin.

P
After a trabeculectomy, what is the risk of the eyelid not resting on the eyeball as it did prior to surgery?

Dr. Anand Mantravadi
Drooping of the eyelid or ptosis can also occasionally occur following any type of intraocular surgery. In many cases, with time, it improves. Rarely, it persists, but can be corrected surgically at a later date if functionally or cosmetically a concern.

P
Is there any way to control how the bleb will affect the eyelid during the surgical procedure?

Dr. Anand Mantravadi
In short, not really; however, there has been a lot of discussion on how small modifications in surgical technique can help shape blebs to appear a certain way with desirable characteristics. That being said, the way one ultimately heals and forms a bleb is highly variable depending on the patient and can be somewhat less predictable at the onset.

P
Is there more of a likelihood of double vision with shunts in both eyes?  What causes the double vision?

Dr. Anand Mantravadi
The double vision that occurs with tube shunts, if it occurs, is most often transient and self-limited. Early in the post operative period, there can be some swelling of the muscles but rarely does it persist. It is thought that this late persistent diplopia is possibly due to an eye muscle restriction due to scarring. It can be treated a number of ways from conservative measures such as prisms in lenses to surgical options for those situations not alleviated by prisms.

P
Back in May 2006, Dr. Rick Wilson answered in a chat, “A recent study suggested that one year after surgery, trabeculectomy has slightly more complications than shunt surgery, and the shunts were lasting somewhat longer.”  When asked if the study might persuade doctors to perform more shunts, the doctor responded, “Yes, I think we will be thinking possible shunt surgery now on patients who do not require an IOP lower than 16 mm Hg (my bias).”  Have more shunt surgeries been performed since 2006 based on this study?

Dr. Anand Mantravadi
Based on Medicare claims, data, and other surveys, the trends towards offering shunts more frequently and earlier in the treatment of moderate to advanced glaucoma is becoming more and more evident.

The safety profile of tube shunts has been shown to be more favorable over the years and have led to greater utilization. Tube shunts were previously only reserved for very recalcitrant glaucomas that have scarred through other surgeries but are being offered more commonly at this time.

P
Are there more risks in a combined cataract surgery and trabeculectomy than the risks of individual surgeries?

Dr. Anand Mantravadi
There are slightly more risks because it is an additional surgical procedure performed at the same time.  However, combined surgery is an effective modality in certain situations.

P
Who is a good candidate for this combined surgery where the benefits outweigh the risks?

Dr. Anand Mantravadi
If someone has a visually significant cataract, and co-existent glaucoma, combined surgery can be considered. The risk and benefit profile must be individualized to each case.  Sometimes, it makes more sense to perform the glaucoma surgery alone. Sometimes it makes more sense to perform the combined cataract glaucoma operation, and sometimes it makes more sense to perform the cataract operation alone. Again, it is difficult to generalize, but a doctor should tailor decision making to each individual patient.

P
Are there glaucoma medications that cannot be continued for a short period of time when cataract surgery is performed and the patient has glaucoma?

Dr. Anand Mantravadi
This area is somewhat controversial. The prostaglandin class: travaprost, latanoprost, bimatoprost, tafluprost, have been very rarely associated with retinal swelling. After cataract surgery, some surgeons choose to temporarily stop this class of medications, and others don’t find any difference with continuing this medicine. I’m not sure the evidence definitely points to a right approach here.

P
What is a non-penetrating surgery? Are the risks and benefits the same as for conventional glaucoma surgeries?

Dr. Anand Mantravadi
Non-penetrating glaucoma surgery is distinct from conventional filtering or trabeculectomy surgery.  The risks and benefits profile are similar.

P
If we have a working trabeculectomy, who is best to perform the surgery, a cataract surgeon specialist or a glaucoma specialist that operates on cataracts?

Dr. Anand Mantravadi
Both are trained to perform cataract surgery and it can be successfully performed by either specialist.

P
What is the progression of a pre-existing cataract after any glaucoma surgery?

Dr. Anand Mantravadi
In the Collaborative Initial Glaucoma Treatment Study (CIGTS), a randomized controlled trial, the trabeculectomy group had a three-fold higher risk of cataract progression at the end of the trial. What I counsel many of my patients is that there are reversible conditions and irreversible conditions.

P
What is the risk of a trabeculectomy failing after a cataract surgery?

Dr. Anand Mantravadi
If glaucoma surgery is indicated to preserve the health of the optic nerve, should a cataract develop, it can be removed at a later date. However, the health of the optic nerve cannot be restored to date.

P
What causes continued degradation of a visual field after glaucoma surgery?

Dr. Anand Mantravadi
The risk of trabeculectomy failure cannot be generalized as it depends heavily on the patient population. Some groups are at higher risk of surgical failure than others.  Continued degradation of the visual field can be due to cataract progression.  Glaucomatous progression is still possible. The field can be affected by any condition that affects the health of the optic nerve or retina such as a “stroke” of the nerve (ischemic neuropathies) or a vascular occlusion.

P
What does ischemia mean?  Is it the lack of blood flow, or abnormal blood flow, or dead?

Dr. Anand Mantravadi
Ischemia refers to inadequate blood supply that results in a characteristic damage.

P
If some trabeculoctomies fail and we need a shunt, how can the shunt lower the IOP to a single digit in advanced glaucoma?

Dr. Anand Mantravadi
Shunts can lower to single digits but that’s not typical. Occasionally, shunts in combination with medications can achieve low target IOPs.

P
If one has a working trabeculectomy and need cataract surgery, what are the odds that the trabeculectomy will fail due to the cataract surgery?

Dr. Anand Mantravadi
A specific number is hard to quote given the variability in technique or patient populations.   In the literature, it is clear that cataract surgery raises the risk of a trabeculectomy failure.

Moderator
Thanks, Dr. Mantravadi. Your time and knowledge are much appreciated

Dr. Anand Mantravadi
Thanks everyone!

   

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The Glaucoma Service Foundation’s mission is to preserve or enhance the health of all people with glaucoma and to provide a model of medical care by supporting the educational and research efforts of the physicians on the Wills Eye Institute Glaucoma Service, the largest glaucoma diagnosis and treatment center in the country.
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