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Ask the Experts 2011 Archive | 2010 Archive | 2009 Archive | 2008 Archive
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Q: I had SLT three weeks ago in both eyes. My IOP was 24 in both eyes before SLT treatment. After one week of SLT, IOP was still 24. I am using Doutrav drops. My doctor asked me to see him after one month. Why, even after SLT, is my IOP still 24? How long will it take to achieve the target IOP? I was diagnosed with OAG in 1992. Belkin: SLT, like other glaucoma treatment methods, is not effective in all patients. Since we presume that the ophthalmologists who treated you used the optimal parameters, it seems that you are one of the patients who do not respond to this therapy and should resort to other treatments.Please note that having undergone SLT does not interfere with the effectiveness of other treatments. Q: Do I need to retreat a patient who has been treated by SLT one year ago? The patient’s IOP (immediately after SLT treatment) was 18~20 mmHg with no medication, however one year later, the IOL raised to 22 mmHg. Do I need to re-treat with SLT or add medication? Nagar: This depends on the initial IOP and on what is the target IOP. If initial IOP drop was around 20% or more, and if target IOP is around 18 mmHg, then I recommend to repeat SLT treatment.
Q: I am scheduled for SLT soon and I have a few concerns. I had breast cancer 5 years ago and underwent radiation for 7 weeks. Can you tell me if SLT is a form of radiation and is it safe for me to undergo this procedure. I want to clearly avoid any radiation. I hope you can address my concerns. Belkin: There is no cancer risk whatsoever involved with SLT. The laser light involved in SLT is completely unassociated with cancer, it is just concentrated visible light, unlike x-rays or ultraviolet which are associated with cancer. The laser light beam used in SLT is about 10.000 times weaker than the laser light used in other laser eye treatments. It is so weak that it is invisible, although this green light can be seen when stronger. To alleviate your apprehensions even further - the laser light beam is directed into a certain part of the eye only and does not spread. Q: I have a Solo SLT laser and have completed a couple of thousand SLT treatments. Can you please advise where to find information about retreatment, more specifically, retreatment on a regular basis? I have heard of colleagues who retreat i.e. a quarter of the trabecular meshwork annually to maintain the obtained, lowered IOP. Belkin: There are no studies on "REGULAR" treatment of POAG, or any other type of glaucoma, by repeat, partial or total angle, SLT. There is a lot of data, however on repeat SLT being effective: 1. Russo et al. Eur J Ophthalmol 2009; 19: 429 - 434 2. Hong et al. J Glaucoma 2009;18:180–183 Repeat Selective Laser Trabeculoplasty. 3. Jindra in his retrospective study of over 2000 eyes [presented in ARVO and AAO 2007] concluded that: In this clinical series, Selective Laser Trabeculoplasty:
There is also plenty of additional evidence to the efficacy of repeat SLT in conference presentations, e.g.,: 1. Lai J: Repeatability of Selective Laser Trabeculoplasty [SLT] [abstract] ARVO 2005; 2. de Leon JS: Efficacy of Multiple Selective Laser Trabeculoplasty Treatments in Open-angle Glaucoma [abstract] ARVO 2005; 3. Bournias TE: Repeatability of Selective Laser Trabeculoplasty [abstract] AAO 2006. So to conclude - the idea of repeat SLT is good, but one should not treat when there is no high IOP. The idea of repeat SLT for eliminating eye drops is also sound. Q: I am currently using the Latina SLT lens for my SLT procedures. However, I prefer the view and magnification of the Magna View Gonio Laser Lens from Ocular Instruments. I understand that the magnification of the image with the Magna lens will decrease the spot size by about 30%. Also, the energy delivered will be higher. I would prefer to use the Magna lens and adjust the energy settings accordingly. Anybody doing this? Any other downsides that I may not be aware of? Also, is there any benefit to pretreating with Pilo to make the angle more visible? I would imagine that would work well in narrow angle patients, but what about others? Please refer to the following article: Not All Gonio Lenses are Created Equal [1] written by Prof. Michael Belkin (Tel Aviv University) regarding the use of various Gonio lenses available on the market for SLT treatment. When Ms. Madhu Nagar (Clayton Eye Centre) was asked about her experience with Pilo, she advised that she only uses it to open up slightly narrow angles, not otherwise. 1. Michael Belkin, MA, MD, Regenerate, vol. 6, March 2008. Q: I would like to know if SLT is performed on people who don't have glaucoma but run a high end of normal pressure on their eye? I have been running a pressure of 18 to 22 for years and would like to know if this is a precedure for me? Belkin: SLT will reduce the intraocular pressure for a few years in most people who have ocular
hypertension [high pressure with no signs of nerve damage] and those
with borderline high pressure.
The expected degree of reduction will be small, as the main factor
determining the reduction is the pressure before treatment - the According to a recently
published evaluation [Heijl et al. Natural history of Open-Angle
Glaucoma, Ophthalmology Dec. 2009; 116:2271] only 7% of untreated
patients with recently diagnosed glaucoma will deteriorate. The
likelihood of people without glaucoma is probably lower. Therefore, other factors, such as age and family history, must be included in the decision to treat a person with borderline
intraocular pressure or just to carefully monitor and treat only when glaucoma actually appears. Q: I had SLT done on my eye one week ago. Within 48 hours I developed corneal edema which my doctor said is temporary. How long will this last and is there some kind of specific treatment for it? Belkin: Corneal edema is usually caused by the contact lens used to deliver the laser beam, but one cannot be certain without examining the eye. The edema usually disappears within a few days, but again one cannot be certain without examining the eye and analyzing the severity of the edema.
Q: Can SLT treatment make later treatment with trabeculectomy more problematic? Belkin: There is no clinical trial comparing trabeculectomy after SLT with trabeculectomy after medicines or after ALT. From anecdotal reports it seems that there is no effect of SLT on subsequent trabeculectomy. This is to be expected since SLT does not produce any significant trabecular damage. Electron-microscope study in the area of SLT lesions, showed that the beams of the trabecular meshwork were intact except for rare crack-like defects between preserved beams. There was a total absence of coagulative damage and the endothelium was continuous, with a few vacuolated cells. [Kramer TR, Noecker RJ: Comparison of the morphologic changes after selective laser trabeculoplasty and argon laser trabeculoplasty in human eye bank eyes. Ophthalmology 108:773--9, 2001]. Q: How do you proceed to wash out medications before SLT? Nagar: I usually start by washing off the drop that the patient took the longest. I have left all my patients on prostaglandins as compliance is better with once a day dosage and try and wash off every other medication. I do also spend some time with my patients before washing off treatment to understand their routine, issues with any with treatment regimen and then agree on a treatment plan with them. Q: Is SLT efficacious in pseudophakic eyes? Nagar: Unlike ALT, SLT works with pseudophakic patients and I could achieve a 20% IOP decrease or more in almost all eyes treated. Q: Might the SLT procedure diminish vision or adversely affect vision? Belkin: The answer is no, SLT was never reported in the medical literature to cause reduction in vision. There are cases of reported blurring of vision after the treatment which is always temporary and is probably due to the contact lens used to deliver the therapy. SLT leads to few side effects almost all been transient and minor. Early post-operative elevation of IOP in some patients has been observed in all published series, whether or not the patients were receiving perioperative anti-hypertensive treatment. In all of those cases it resolved quickly with observation or additional antihypertensive medications. [1] There is only one case series of four cases with sustained IOP elevation following SLT in eyes with a heavily pigmented trabecular meshwork, three of them needed trabeculectomy. [2] More common side effects, namely anterior chamber reaction, redness, pain, and blurred vision, are all transient and without sequelae in all studies. SLT is actually so free of serious side effects that some minor transient ones merit reporting, e.g., two cases of transient corneal edema [3] and one of transient hyphema. [4] 1. Barkana, Y and Belkin M. Selective Laser Trabeculoplasty. Survey of Ophthalmology 52:634-653, 2007 2. Harasymowycz PJ, Papamatheakis DG, Latina M, et al: Selective laser trabeculoplasty (SLT) complicated by intraocular pressure elevation in eyes with heavily pigmented trabecular meshworks. Am J Ophthalmol 139:1110--3, 2005
3. Moubayed SP, Hamid M, Choremis J, Li G. An unusual finding of corneal edema complicating selective laser trabeculoplasty. Can J Ophthalmol. 2009 Jun;44(3):337-8. 4. Shihadeh WA, Ritch R, Liebmann JM. Hyphema occurring during selective laser trabeculoplasty. Ophthalmic Surg Lasers Imaging. 2006 Sep-Oct;37(5):432-3. Q: I would like to know the protocol for this SLT procedure. My mother had this treatment done in each eye for lowering eye pressure. She has a diagnosis of glaucoma. The doctor has recommended that she needs to have this procedure done in each eye every year. Is this safe for her eyes? Is that the accepted protocol? Nagar: SLT is a safe treatment modality and yes it is safe to repeat. Protocol for repeat treatment is "NOT TO REPEAT EVERY YEAR" but to repeat as and when required i.e. when the effect of first treatment wears off. For 60% of patients that may be 5 years. Q: I am a white 59 year old female, one week post 360 degree SLT. I was on 6 different medications pre- and post-SLT. One day after procedure IOP was down to 11. But two days later after reducing medication slightly, 1OP was back up to 30. Is it too early to determine if SLT was a failure? Should maximum drugs be taken again? Can the procedure be repeated sooner rather than later? Belkin: Immediate rise in intraocular pressure (IOP) after SLT is not uncommon. The IOP settles between one week and one month after the procedure. At one month one can usually determine with confidence how effective the treatment was and act accordingly. Q: Can I use SLT in juvenile glaucoma; primary or secondary angle closure glaucoma and in post-inflammatory glaucoma if the inflammation decreases? What are the contra indications of SLT? Melamed: SLT can be used for Juvenile Glaucoma. However, the success rate is lower than with the other types of Open Angle Glaucoma. Patients with Juvenile Glaucoma respond differently to SLT. A reason for this could be that their trabecular meshwork (TM) is not very pigmented. SLT is not indicated for primary nor secondary Angle Closure Glaucoma, unless iridotomy is performed and an opening is created. Studies have shown that the success rate with SLT following iridotomy is relatively good. SLT is not that active in patients with inflammatory glaucoma, even if the inflammation decreases. We may assume that because there already is an inflammation and the IOP did not go down, creating another inflammation with SLT will not help reach the target pressure. SLT has not been shown to be suitable for the following conditions: primary or secondary narrow-angle glaucoma, inflammatory or uveitic glaucoma, any disease process or malformation that blocks the angle and anytime there is an unclear view of the TM. Q: I have been using SLT for three years with good results and no major complications. However one of my co-workers says that he experienced permanent IOP rise in one eye after 360 degrees SLT. (Average energy level was 0.8 mj, with about 100 spots; angle pigmentation was moderate; diagnosis was primary open angle glaucoma and pre-laser IOP was 28 mmHg, rising to over Melamed: Yes, I have already experienced such cases. In the hours following SLT treatment, one should expect 3 to 11% IOP rise, and in a very small percentage of patients, this IOP rise can be permanent (the case you are referring to seems to be among this small percentage of patients). If after one month the patient is not responsive to additional medical treatment, trabeculectomy should then be performed – just like what was done by your co-worker. Q: Is SLT indicated in advanced glaucoma (C/D>0.8)? Belkin: SLT is indicated for IOP reduction in POAG at any stage of the glaucomatous neuropathy. It can be expected to reduce the IOP by 20% or more in 70% of patients. The higher the pre-SLT pressure, the higher the reduction. It does not matter what the previous therapy was. Q: Would you recommend performing SLT on a young patient with juvenile open-angle glaucoma and earlier suspicion of gonio-dysgenesis? The patient is currently treated with Ganforte, with insufficient IOP control (25mmHg). Nagar: The answer to this question is not that simple. There are various factors that need to be considered prior to deciding on treatment modality.
Q: Is there any way to pre-determine whether or not the patient will respond to SLT? Belkin: To the best of my knowledge this question has not yet been answered. However, although SLT is effective in 60 to 80 percent of OAG patients only, its use is exceedingly rarely fraught with any risks. Thus the best method of determining who will respond is to treat – if the IOP is sufficiently reduced at two weeks the treatment was successful. (1) There have been numerous investigations trying to define the pre–treatment parameters which determine the extent of IOP reduction. Most of the reports agree that the only parameter which is consistently predictive is the pre-treatment IOP – the higher it is, the greater the reduction. This parameter is common to all glaucoma therapies. The extent of IOP reduction by SLT does not depend on other factors such as age, sex, race, family history, type and severity of OAG, pseudoexfoliation, number of glaucoma medications (unlike ALT), previous ALT (unlike ALT), being performed as primary therapy, systemic hypertension and diabetes mellitus. There is currently no consensus regarding the prognostic effect of heavy trabecular meshwork pigmentation. (1) Johnson PB, Katz LJ, Rhee DJ. Selective laser trabeculoplasty: predictive value of early intraocular pressure measurements for success at 3 months. Br J Ophthalmol. 2006; 90:741–743. Nagar: In my experience it is not possible to predetermine whether a patient will respond to SLT, but if a patient does respond to treatment then success is directly proportional to baseline IOP. As Michael explained, the higher the baseline IOP, the greater the IOP reduction in responders will be. IOP reduction is also dependent on the degree of area treated; IOP reduction achieved with 360 degree SLT treatment is comparable to IOP reduction achieved with Latanoprost drops. (Reference - M.Nagar, A. Ogunyomade D.P.S.O’Brart, F. Howes: A randomised, prospective study comparing 900, 1800 and 3600 Selective Laser Trabeculoplasty with Latanoprost 0.005% for the control of intraocular pressure in Ocular Hypertension and Open Angle Glaucoma; British Journal of Ophthal: Issue Nov 2005). Q: When performing SLT, is it recommended to remain right under or at the level of bubble formation?
Thus the common practice of reaching the bubble forming energy level and reducing it slightly for the rest of the treatment is appropriate and effective. It must be emphasized however, that the optimal energy level for maximal IOP reduction is yet to be properly determined by a large controlled study. It is not unlikely that other energy settings will make SLT more effective. Nagar: While performing SLT, recommendation is to perform treatment at sub-threshold energy levels to get the best response. The degree of pigmentation varies throughout trabecular meshwork and I mostly titrate the energy level at the 6 o’clock position and adjust energy levels during treatment but not for every shot. I like to see some reaction i.e. champagne bubbles for about 25-30% of shots.
Q: When SLT should be or can be introduced in the treatment cycle? Nagar: I introduced SLT as adjunctive treatment for patients uncontrolled on maximum tolerated medical therapy, previous failed ALT, poor/non compliant patients or intolerant to medical treatment. Gradually over time SLT proved to be a safe and an effective treatment modality and now SLT can be safely offered as first line treatment option. Q: What types of glaucoma can be treated with SLT? Nagar: Open angle glaucoma i.e. Primary open angle glaucoma, Pigmentary glaucoma, Pseudoexfoliative glaucoma and Ocular Hypertension all respond well to SLT (Success criteria 20% IOP reduction, Success Rate 75%). I have successfully treated Traumatic glaucoma - Angle recession glaucoma (2) patients, Glaucoma secondary to complicated cataract surgery (7) and Juvenile glaucoma. Q: What adverse effects do patients experience? Nagar: Adverse Effects are transient and minimal. Most common adverse effects are Mild discomfort during treatment, Blurred Vision for 10-15 minutes, Sore eyes for 2-3 days and post SLT IOP spike. Occasionally patients may experience headache or migraine after treatment and photobhobia for a day or two. Q: Schedule of post-treatment follow-up – ideal follow-up periods? Nagar: I review my patients one week, one month and three months post SLT and then every six months. Q. How long after treatment is the optimum pressure reduction reached? Nagar: IOP reduction following SLT is observed on Day 1 but 8-10% patients are “Slow/Late Responders” and response may be seen between 4-12 weeks time. Q: When can you start taking patients off meds post-SLT? Nagar: I prefer to wash off treatment prior to SLT rather than post SLT because higher the Baseline IOP Greater is IOP Reduction Q: Is it necessary to perform a washout before SLT treatment? If so, what type of washout do you recommend? Nagar: It is not absolutely necessary to wash out anti-glaucoma drops prior to SLT. Options are:
Personally, I prefer to wash treatment off prior to SLT and follow EGS guidelines:
Q: When do you consider a patient for re-treatment? Nagar: Before I answer this question I would like to define "re-treatment". divide Retreatment into a) Enhancement & b) Repeat treatment a) Enhancement of SLT: Further SLT treatment following Initial 180° treatment is "Enhancement of treatment" i.e. treating virgin trabecular meshwork. b) Repeat/Redo: SLT following 360° or two 180° treatment is "Repeat Treatment" or "SLT Redo" i.e. treating previously treated trabecular meshwork.
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