Lecture: Glaucoma in the Myopic Eye

[Claire] Good morning, everyone. My name is Dr. Claire Wright from Hamilton Eye Institute. I’m going to go ahead and share my screen. And I’m going to be discussing today glaucoma in the myopic eye diagnosis and management tips.

I have no financial disclosures.

These are our lecture objectives. The first one will be to detail optic nerve features in the myopic eye. We’ll also describe common retinal nerve fiber layer imaging and visual field findings in the myopic eye. And then we’ll try our best to understand the nuances of glaucoma management in highly myopic patients.

Why should we care about this relationship between glaucoma and myopia? This is a review for many of us eye care providers but glaucoma is the leading cause of irreversible blindness worldwide with 67 million people affected and 10% of whom are blind. Glaucoma in the United States where I am lecturing from, affects 2.2 million people and it is the second leading cause of irreversible vision loss in people over 40 years of age with the first being age-related macular degeneration. The incidence of glaucoma is increased, which we’ll discuss in this lecture, in patients with greater than minus six diopters of myopia. And myopia is actually increasing worldwide. There’s a number of studies, especially Chinese-based studies, that have demonstrated very clear rapidly increasing rates of myopia and it’s postulated that this may be to increased time spent indoors, perhaps increased screen time, et cetera.

How do we define high myopia? The classic definition that you see, I think most consistently across the ophthalmology literature, is axial length greater than 26.5 millimeters and/or spherical equivalent greater than minus six diopters. That’s just one of the answers here to my poll questions. This is a related point, in the Western world at least, there’s a fairly high incidence of refractive laser correction for myopia which further complicates our picture. As in patients, once they’re surgically corrected, may not seek regular eye care. And this surgical correction does not mitigate the risk of myopic-related complications. A lot of reasons why we should care about this lecture.

Let’s talk about myopia as a risk factor for glaucoma. There’s a number of studies out there but I wanted to highlight two in particular. The first being the Blue Mountains Eye Study which is a cross-sectional population study based in Australia. This used general estimating equation models to quantify this relationship between myopia and glaucoma. And they found glaucoma incident is present in 1.5% of eyes without myopia, 4.2% of eyes with low myopia, and 4.4% of eyes with moderate to high myopia.

Moving on to the Beijing Eye Study. This was another cross-sectional based population study that used morphological assessments of the optic disc photos which they defined as optic disc glaucoma to try to shed light on this relationship between myopia and glaucoma. And they found that in patients with both marked myopia and high myopia, they defined this as marked myopia as minus six to minus eight diopters and high myopia as greater than minus eight. These patients had a higher incidence and frequency of optic disc glaucoma than those with moderate myopia, low myopia, emmetropia, and hyperopia. This appears to be a risk factor according to these two large studies.

Why are myopic eyes predisposed to glaucoma? Are they? There’s some theories here that make sense to me and a number of other ophthalmologists in the literature. The thought is that due to axial elongation in these long myopic eyes, these patients then have thinner lamina cribrosa which then in turn results in compromised structural support for these neurofibral layers. Other studies have shown that the shearing forces of scleral tension across this thin lamina cribrosa is increased in myopia. But it’s important to keep in mind highly myopic eyes can be associated with optic nerve head abnormalities that can create diagnostic challenges, which we’ll talk about.

Let’s talk about the optic nerve findings in myopia. Highly myopic nerves can exhibit any or all of the following: nasal insertion of the optic nerve, tilted and/or large disc, shallow cup. And then peripapillary findings such as a scleral crescent wherein you actually see due to thinning of the axial elongation, you actually see the sclera as well as peripapillary atrophy. Of course, as many of us know, these posterior segment abnormalities can extend beyond the optic nerve. With altered fundus pigmentation or increased tessellation, temporal displacement of the superior/inferior nerve fiber layers, posterior staphylomas, myopic macular degeneration, and peripheral retinal abnormalities such as lattice degeneration, holes, tears, et cetera.

The following slides are a couple of photos which demonstrate these funny looking nerves, to be frank, both in the literature and I have a couple of my own. These patients, I’ll just give an example of how I personally would interpret these disc photos. I would describe these as optic nerves are nasally inserted with appreciable scleral crescent, peripapillary atrophy, probably more peripapillary atrophy, although the whitening looks kind of like a scleral crescent. Nasal nerve insertion, peripapillary atrophy, but not much cupping. But the cups do look a little shallow. I do my best to describe, but of course I take disc photos in all of my glaucoma patients, not just the ones with funny looking myopic nerves.

Let’s talk about these photos. Again, how I’d describe, and this is from a wonderful American Academy of Ophthalmology EyeNet article. These two photos demonstrate myopic nerves. The left shows nasal insertion with not much cupping, which is great, healthy neuroretinal rim. Versus the right image, again, slight nasal insertion with a larger cup and a thinner neuroretinal rim compared with the left. These are photos that demonstrate the diagnostic quandaries in myopia but at least these two compared side-by-side you can see there’s more appreciable cupping the right photo then the left photo.

Let’s talk about these photos. This is actually a patient of mine that we wrote up for ophthalmology management. Who although the patient did not have glaucoma, had degenerative myopia. These nerves, that’s a significant myopic scleral crescent, 360 around this nerve. Speaking of the nerve, those nerves, really difficult to ascertain that cup-to-disc ratio and that’s what I put in my note. If the cup is so shallow that I can’t really even make out the borders of the neuroretinal rim, I just don’t even quantify a cup-to-disc ratio and just say a poorly discernable cup-to-disc ratio. These particular optic nerves are pretty impressive for myopia and associative myopic nerve findings. Thankfully the patient was not being treated for and I don’t think had glaucoma, but had a couple other issues including myopic maculopathy.

Just to continue our discussion of nerve fiber layer imaging in myopia. This relationship between axial length, spherical equivalent, and nerve fiber layer thickness has been explored. In this 2006 study, these researchers found that the average RNFL score decreases with increasing axial length and spherical equivalent. This RNFL score was significantly lower in high myopia versus low to moderate myopia.

This second study, 2009 study found similar results wherein the average decrease of the nerve fiber layers, average score, decreased by seven micrometers per one millimeter increase in axial length. And then they found that for refractive myopia, this relationship was not as strong. This makes sense because of axial myopia, if you’ve got stretching of the scleral and thinning, so that makes sense that with increasing axial length you have decreased RNFL thickness.

This is just a sample of a Heidelberg RNFL image of one of my patients, a patient with myopic nerves that actually deescalated treated for. This patient was deemed to have glaucoma by a referring provider, sent to me for a second opinion, was on prostaglandin analogue. And just looking at these RNFLs we’ll start with the left one. We’re not going to get too much into how to interpret an OCT, but what I look at is, I tend to look at, of course, confirming the patient’s name. I tend to look at the red-free image first, just work my way top to bottom. The image on the left, that’s actually a fairly normal looking nerve in terms of nerve insertion, seems to be good centration of that nerve fiber layer, tracking line, not too much peripapillary atrophy, scleral crescent. Looking on down at the global thickness score. It looks okay, fairly normal. Unimpressive, which is good. I don’t want to be impressed in clinic.

The left nerve, however, you can see in the red-free image there’s a little bit of nasal insertion, maybe a little bit of tilt. You also see that temporal either scleral crescent or peripapillary atrophy that makes you wonder, hm, I wonder if this nerve fiber layer tracking scan is picking up the peripapillary atrophy as opposed to the actual temporal border of the nerve. I’m suspicious of it as I work my way down and then I do see, I look at the global thickness score and I see some superotemporal thinning. I’m very hesitant to put all my weight into nerve fiber layer scans in myopic nerves is the long and short of it.

Why can this be so confusing in myopic nerves? It’s important to keep in mind that current nerve fiber layer scans, these programmings, the way they work is that they rely on a normative database. That’s how you get the green, yellow, red. And it’s age-related but oftentimes these normative databases exclude eyes with high refractive error. For instance this Cirrus HD OCT by Zeiss, their normative database is composed of eyes with the average spherical equivalent of minus 0.82. And this basically can result in a high amount of what we call red disease or false positives in non-glaucomatous myopic eyes. Which potentially could be eliminated by incorporating more myopic eyes in this database and result in less over treatment of otherwise healthy eyes.

This study in 2016 actually looked at what it would look like to have a myopic normative database with regards to RNFL imaging. These researchers, they basically created a normative database of 180 highly myopic eyes with the average spherical equivalent of minus eight diopters, which were otherwise healthy, no retinal disease, et cetera. And they evaluated sensitivity and specificity of this normative database by using 46 highly myopic but otherwise healthy eyes and 74 highly myopic glaucomatous eyes and they evaluated RNFL thickness map of an SD OCT. And they found that their myopic normative database that they built showed a higher specificity than the standard built-in database without affecting the sensitivity of the test. I think that’s interesting.

Again, another example of one of my patients in a Heidelberg RNFL OCT that this one appears more glaucomatous. You can tell working your way top to bottom, that red-free image there’s more cupping there. There’s also peripapillary atrophy or a scleral crescent, hard to tell on the red-free image. Which could confound the RNFL global thickness score, but you can see in this red-free image there’s clearly cupping. I’m already suspicious for glaucoma being present in this myopic eye before I even get down to looking at the global thickness score and the average score of each of the quadrants of this optic nerve.

We’re going to briefly mention visual fields in myopia. High myopia can cause visual field changes. That could be due to either optic nerve irregularities which we’re clearly focusing on in this lecture, and/or retinal anomalies. Visual field defects that favor myopia over glaucoma include, but are not limited to, temporal field defects that usually respect the midline as in a tilted disc. Also enlarged blind spot. And this may be due to peripapillary atrophy or scleral crescent. Visual field defects that favor glaucoma in the setting of myopia are the classic visual field defects that we’re all familiar with: nasal step, arcuate scotoma, paracentral scotomas, things like that. You keep in the back of your mind when we’re interpreting a visual field, this patient’s got myopia, it still doesn’t really change how I interpret the visual field. If they’ve got a glaucomatous visual field defect, okay, that’s probably glaucoma. I’m not as thrown off in my visual field interpretation that I am in my nerve fiber layer interpretation.

This is an example of myopic eyes without glaucoma that can demonstrate visual field abnormalities.

Let’s briefly talk about disc photos in glaucoma monitoring. I think that disc photos are very valuable particularly in this setting because we get less noise. Think about that red disease in RNFL OCTs, it throws you off a little bit. And these disc photos, they’re just, it’s a picture, it is what it is. It’s not impacted by peripapillary atrophy, scleral crescent, disc tilt, nasal insertion, et cetera. And I think it can better monitor for change than RNFL. It’s just less confusing for the person interpreting. I think that you can perhaps better identify increased cupping, new rim notching, an increase in peripapillary atrophy, vascular changes, et cetera. Again, I mentioned this before, I do disc photos in all of my glaucoma patients annually. But I also do it if I find a new disc hemorrhage or a new finding.

I also want to talk, hit lightly, the management of glaucoma in myopia. Of course, as is with all glaucoma, the goal is to lower the intraocular pressure, of course. But there are a few caveats I wanted to bring up. It’s very important to keep in mind the risk of hypotony maculopathy with incisional glaucoma surgery, especially in young patients. This is thought to be due to the thin, stretched out, less rigid scleral. And this can actually occur with numerically normal IOP. Numeric hypotony is less than five millimeters of mercury. I’ve seen hypotony maculopathy with epithelial folds in the cornea and Descemet’s folds with a pressure of 10 to 12. We shouldn’t be dogmatic with the IOP readings.

How can we mitigate this risk of hypotony maculopathy? We can make surgical modifications. In trabeculectomy this can involve potentially putting in more than your standard number of scleral sutures in that flap. One of my mentors in fellowship detailed for me how one of her myopic young patients in whom she performed a trabeculectomy put something like eight sutures and the patient still had some hypotony post operatively. It’s impressive what these patients may require. In tube shunt surgeries, you may need to leave the patient with a higher intraocular pressure than you typically would at the end of your surgery. Leaving, perhaps, more OVD in the eye and very low threshold to refill the anterior chamber post operatively.

What about selective laser trabeculoplasty in high myopia? And interestingly, and I need to look into this, I had a patient who in her history had a retinal detachment following your selective laser trabeculoplasty done by another provider. And actually looked in the literature, I don’t see any case reports of this so I’m going to look it up, but I’d be interested to hear if any of my audience have had this issue before. It’s given me pause about recommending SLTs in highly myopic patients. Just something to think about.

So now, again, this is the first question. High myopia, how do you define it with regards to axial length and spherical equivalent? Give you a few seconds to answer. Great job! All right, the answer is minus six diopters and 26.5 millimeters for spherical equivalent and axial length, definition of high myopia. Great, I’m so glad most of the audience got that.

All of the following nerve features can be seen in high myopia except? Tilted disc, scleral crescent, peripapillary atrophy, or disc hemorrhage. Yes, excellent. The answer here is disc hemorrhage.

Third question. Which of the following statements is false? Optic disc photos are a useful means of monitoring for glaucoma in myopia. RNFL in myopia can be subject to green disease or false negatives. RNFL in myopia can be subject to red disease or false positives. And visual field in myopia in the absence of glaucoma can demonstrate enlarged blind spots. Which of these is false? Okay, all right, most of you all still got the answer I think is correct, which is RNFL in myopia can be subject to green disease or false negatives. I’m sure some of my very bright audience members will have an example wherein they had a false negative green disease RNFL scan so I apologize. But I should have made it more absolute. But going through each of these I mentioned optic disc photos are a useful means for monitoring for development or progression of glaucoma. I think optic disc photos are really useful especially if they’re really funny looking. It’s good to get that. Red disease, I see that very commonly in RNFL imaging in myopia wherein perhaps that RNFL nerve fiber layer tracker is picking up on peripapillary atrophy or a scleral crescent instead of the temporal rim of the nerve, thereby flagging this as red when truly it’s just not catching the correct area. And then you can see enlarged blind spots in myopic eyes I think due to peripapillary atrophy or scleral crescent, but I could be wrong. But that is something that I have seen in the literature, enlarged blind spots in visual fields.

I just want to review a couple lecture takeaways here. I do ask, I didn’t get too much into this I mentioned at the beginning, but do ask patients about refractive history. I ask all my patients about previous ocular surgeries including lasers because refractive correction for myopia can impact IOP measurements because it affects the corneal thickness and it does not mitigate the risk for myopia-related complications. These patients with high myopia, still need to be counseled on the risk of retinal detachment et cetera.

I also want you all to keep in mind the myopia-related nerve appearance when interpreting visual fields and RNFL scans. The key is monitoring for change. You don’t expect to get progressive myopic nerve changes in a patient because if they were born that way it shouldn’t progress. You can repeat these testings and if there’s change that’s suggestive of glaucoma. If in doubt, pump the brakes, don’t treat, just observe and just watch the patient.

I also think that disc photos may be more useful for monitoring for change in myopic eyes with glaucoma than an RNFL scan, which has a lot of noise and it can be a little confusing. I think it’s also important to be judicious with patient selection, always, but especially in myopic eyes when you’re deciding on incisional glaucoma surgery due to the risk of hypotony maculopathy. And as in all patients, it’s important to take an individualized approach in management. You have to factor in things like age, life expectancy, overall health, status of the fellow eye, socioeconomic factors, ability to follow up, it’s complicated. I think one of the best advice I got as a resident was to not be dogmatic in the management of patients with glaucoma. It’s not a one-size-fits-all approach. You have to look at the big picture. I think the same goes for myopic patients with glaucoma.

I wanted to end before we get to the Q&A, I wanted to actually draw attention to this old paper in the literature. This is actually the first paper published about examining the relationship of glaucoma in myopia, at least the first paper I could find. Published in 1926, almost 100 years ago. Arnold Knapp, Dr. Knapp, discussed his observations about this relationship between myopia and glaucoma. and I wanted to read this first quote from him that’s from this paper. “Although the diagnosis of glaucoma in these cases is difficult, repeated tonometric and perimetric examinations will indicate the line of treatment.” I think that just really sums up well a lot of the things I discussed about and clearly that advice and suggestion has stood the test of time for nearly 100 years. Watch the patient, repeat testing, and if there’s change, treat.

Now also in this paper, it’s actually a really fascinating paper, wherein after maybe about two pages of Dr. Knapp’s observations, there’s several pages of discussion wherein ophthalmologists from around the country wrote in with their observations. And then Dr. Knapp went through each comment individually. And it’s a really fascinating paper. But I wanted to draw attention to this other quote from a Dr. Tyson in New York which I’ll read, it’s a little long. “In the cases with high myopia and extensive posterior sclerochoroidal changes, with moderate cupping and relatively slight increased tension, or pressure, it is possible to overlook the glaucomatous conditions. I have recently found records of two cases in which this occurred, the previous examinations having been made in the offices of competent ophthalmologists.”

I think that unfortunately I do see this where sometimes, and forgive the pun, but sometimes as ophthalmologists we get myopic in our treatment of patients or our approach to patients and we fail to pick up on things that are outside our tunnel vision. Sorry again for the other pun glaucoma, but I get second opinions from other providers or patients seeking it out where they have glaucoma and it just so happens that their high myopia just confuses and muddles the picture. I think that this is a challenge for all of us but we just have to be vigilant and do our best to take care of our patients.

These are my references. I want to thank, in particular, our photography department, our wonderful photographers. And this is my email address should anyone have questions or comments which I welcome. And thank you in advance. But I’m by no means an expert, this is just my observations. I’ve seen it a lot in my two years of practice, a lot of myopic patients with and without glaucoma. It’s been really interesting to dig into the literature a little bit in preparation for this presentation.

One question is, your thoughts about relevance of Bruch’s membrane opening, please? Well, to be honest, I need to do more research into that. I see that come up a lot in current and more recent glaucoma papers. To be honest I need to look into that. But I will put that on my to-do list. I do have one provider here at Hamilton who takes that more into consideration than I do. To answer your question, I need to look into it. (laughs)

Let’s move on. The role of trend analysis in glaucoma follow up, especially in suspicious cases under monitoring as glaucoma suspect? I think that we, at my institution here in Memphis, we don’t have, for instance, the RNFL Heidelberg print outs, or some of the Cirrus and Heidelberg scans have a trend analysis report. They had it up at my fellowship but we don’t have it here. I think it can be really useful if you have at your institution where you can track global thickness scores, average scores of each sector of your nerve scan, to see if there’s progression. Because if there’s progression it’s probably glaucoma and you should treat it. Same goes for visual fields, you can print out all your previous fields and look at the mean deviation over time. I think if there’s progression that’s suggestive of change then you should treat. Yeah, I think it’s highly valuable.

Another question, does IOP measurement give different results in highly myopic eyes even though laser vision correction has not been performed? I think that’s a great question. I’m not sure, honestly. I wonder if there’s, gosh, I don’t know. I’m blanking on it now. But there’s a newer measurement of the cornea which some institutions use which measures, basically, the shock absorption of the cornea which is basically a surrogate marker for shock absorption ability of the optic nerve. And I’m not blanking on the name of it. But that would actually be interesting to look at if that measurement differs for patients with high myopia over emmetropic patients. I don’t know the answer to your question but I think that would be an interesting thing to look at.

Another question, in highly myopic eyes with borderline glaucomatous appearance, how long do you suggest to follow the patient and repeat the exam? It depends on what you mean by borderline. I have in our ICD-10 coding in our country there’s high risk open angle glaucoma suspect and low risk open angle glaucoma suspect. Depending on how many risk factors they have I may see them back in either six months or 12 months. If I’m really suspicious but I just can’t pull the trigger on treating for glaucoma, then I’ll have them come back in six months and repeat the visual field specifically. I could be wrong, so correct me if I’m wrong, but I believe in this country you can only repeat for billing purposes an RNFL scan once a year if you want to get reimbursed. That said, if I’m really concerned and do want to repeat I will and just eat the cost. But I would say for highly suspicious nerves, maybe six months. And then for low suspicious maybe 12 months.

Do you have a cut off for doing a tube instead of trab at certain axial length or refractive error? No. I try to avoid, as I mentioned, being dogmatic. I do struggle with that. I base my surgical recommendations based on pressure goals. We don’t have Baerveldts at our institute, we do have Ahmed ClearPaths which are a non valve so you get lower pressures with non valved over valved glaucoma tube shunts. But it just depends on their pressure goal, also ability to follow up and how far away they live. There’s a lot of considerations here. I don’t do it based on the axial length or spherical equivalent.

Hello, Bangladesh. (laughs)

Do you believe refractive surgery or cataract surgery could increase the risk of glaucoma in high myopes? I don’t think so. I don’t have the evidence to quote my response, but I don’t think so. I think that refractive surgery in particular just confounds things and perhaps reduces the likelihood of patients following up as appropriate for basically monitoring for other myopia-related complications. Cataract surgery, no. High myopes you have a high risk of peripheral retinal pathology, intraoperatively and postoperatively after cataract surgery, which then could lead to requiring retinal reattachment surgery, which can then increase the risk of developing glaucoma. But in and of themselves, no, I don’t think so.

How do you differentiate between a myopic cup and glaucomatous cup with fundoscopy? I think I answered that question for the most part in this lecture.

Do you treat myopic patients with anti-glaucoma drugs? Especially children who present with high tonometric readings even though they have, say, a cup-to-disc ratio of about 0.5? No. Again, hard to make generalizations. I avoid being dogmatic, I look at each patient individually. But in general, if the patient doesn’t have a very suspicious looking cup, it depends on a couple of things. If they’ve got high pressure, I look, of course, at their central cornea thickness. In many of my particular pediatric patients, which is included in this question, a lot of them have high central corneal thickness. There’s no direct chart that can compare if your central corneal thickness is this much, then your pressure is this. There’s no verified corrective factor. I look at the big picture. Basically depends on their pressure readings I’m getting, their central corneal thickness, their visual fields if I can get them.

The other complicating thing about children is that these normative databases are done in adults. You have to interpret those with a grain of salt because typically that normative database is made up of patients over 18. The bottom line is I look at the whole picture. And I really don’t like to commit patients to a lifetime of drops if I can avoid it. I just take it patient by patient. Good question though.

What is your routine to follow up high myopia patients? Any investigation tips to watch out for? Depends on if they have or have not glaucoma. Depends on their stage. I generally see my several glaucoma patients every three months for pressure checks and I repeat visual fields about twice a year. Moderate glaucoma patients I see about every 4-6 months and mild 6-12 months. Just things to look out for, peripheral retinal pathology, I dilate these patients twice a year. Low threshold to refer to my retina colleagues, which thankfully I have down the hall from me. And just serial annual disc photography.

How do you approach highly myopic pediatric glaucoma suspects? I think, like I said, it’s a case-by-case thing. I look at the central corneal thickness, try to get visual fields if they’re old enough and able to stand for that. And I try not to commit patients to a lifetime of IOP lowering medications.

Hi, Ecuador. Let’s see. (laughs)

What do you think about the role of ganglion cell analysis in myopic glaucoma? I think that it’s confounded by the same things we talked about as with RNFL OCTs, just with anomalous nerves. But perhaps in patients with nonmyopic maculopathy, looking specifically at that ganglion cell analysis in the macula could be valuable to assess for a progression.

Yeah, okay. Ocular hysteresis. Thank you, Lynette. That’s what I was thinking of. That’s the shock absorption ability of the cornea which is a surrogate marker for the optic nerve. I think that would be interesting to look at if there’s a difference in patients of ocular hysteresis readings in myopic versus emmetropic patients. Thank you so much.

How do you go about in cases of highly myopic patients with anomalous discs and abnormal visual field but normal IOP. This is the diagnostic quandary of my day more often than I’d like to admit. But essentially I do serial disc photography, watch for change. In these repeat visual fields and repeat RNFLs if you’re doing then, I just look for change. And so that’s key. If the pressure’s normal, I’m not going to treat assuming their central corneal thickness is average. And I just basically just watch for change on testing, keeping in mind the confounding variable of myopia.

Once in a while one may encounter an emmetropic patient with an unusual looking disc that may look like glaucoma or high myopia. In such cases I find axial length determination to be helpful as some of these eyes may have long eyeballs with flat corneas or low powered lenses which mask the possibility of long eyeballs. I think that’s a great idea. That’s a great suggestion, thank you so much, because I have a lot of funny looking nerve patients. And I always ask all of my glaucoma patients what their refraction is or I collect it. And if they’re pseudophakic ask what their refraction was pre cataract surgery, if they know. If they don’t know I ask, “Hey, were you really nearsighted because your nerves are funny looking?” But I think obtaining an axial length could be really useful in answering why their nerve looks funny. So that’s great, thank you so much.

Can you talk a little bit more about nasal insertion? When you have the nerve, instead of coming in the eye here maybe at my view, on your view it’s more on the nasal side. Sounds a little silly explaining this, the reason why I note it is that it can basically alter how nerve fiber layer tracking scans. It can result in red disease, where it artificially picks up, hey, there’s thinning here when really that nerve is just tilted and it’s picking up on presence of peripapillary atrophy instead of the neuroretinal rim. That’s why I remark on it and I take a photo of it.

In Black African populations, glaucoma has a relatively high prevalence. Will you advise we start treatment if we suspect glaucoma in moderate visual fields to know if there’s some sort of progression or not? Yeah, that depends on the clinical situation on everything like I mentioned from the patient’s age, life expectancy, status of the fellow eye, ability to follow up, family history. You’ve got to look at everything here. When I’m really suspicious, and this patient has a strong family history, has a thin central corneal thickness, has high borderline pressures, and maybe is hit or miss about following up, yeah, I would go ahead and start that patient on drops. Or recommend selective laser trabeculoplasty depending on how you feel about this anecdotal story I have about that retinal detachment after SLT. I would recommend treatment if you’re really suspicious and you’re concerned about follow-up in particular. Good question.

Some patients, their IOP’s in the normal range but the optic disc is a little bit unusual. I’m not sure what the question says. Does this patient need glaucoma treatment? It just depends, you have to look at everything. The bottom line is if on repeat testing there’s change suggested of progression, you should treat. That’s my opinion.

How often should high myopes have their pressure checked? It depends if you think they have glaucoma or not. I’d discuss my follow-up for mild, moderate, severe glaucoma. But I generally recommend at least annual follow-ups for anyone, but for high myope probably at least biannual just to ensure that their retina is stable.

Good afternoon from Zambia. Thank you, hello.

This question, this person has a patient with a tessellated fundus and a cup-to-disc ratio of 0.45 with normal pressure. I don’t know. I’m not really impressed by that cup-to-disc ratio and especially in the setting of normal pressure. I’d probably monitor that patient but of course you have to look at everything testing, et cetera. But based on the cup-to-disc ratio alone and the normal pressure, okay, I’m not as concerned.

What is your opinion about monitoring choroidal vasculature with OCT-A, for instance, as is been shown the choroidal vasculature appears to be more sparse among high myopes. I think that’s a really interesting question. I don’t know that much about it and I need to look more into it. But I believe our institution actually is in the process or has an OCT-A, shows you how clued in I am to my surroundings. I think that would be a really interesting area of study or things to look at. And could be a useful means of monitoring for glaucoma again as a surrogate marker for nerve disease if there’s an increased vascular drop out. I think that could be really interesting.

How would you best approach a myopic patient with stubborn IOP that defers medication. With stubborn IOP you mean borderline high pressure, if the patient, this gets into a kind of interpersonal challenges that one may have with patients. I’d probably want to get into why that patient is deferring medication and do a little bit of motivational interviewing just to see why they’re not preferring to go that route. I have a couple of challenging patients that still for some reason see me but decline all therapies I recommend. Which makes me not want to perform surgery on these patients because I worry about follow-up and compliance. These patients are really challenging. I don’t really have an answer. If you have an answer, let me know. (laughs)

How good is Xalatan or Misopt for management of glaucoma? I’m not sure what Misopt is but Xalatan is a prostaglandin analog. I am a big fan of prostaglandin analogs. My preferred initial treatment in general with glaucoma is recommending selective laser trabeculoplasty or prostaglandin analog. I think the prostaglandin analogs are great.

Let’s see. How much of pressure should be reduced in normal tension glaucoma cases? We didn’t really get into that. But according to the normal tension glaucoma trial study that should be reduced by 30% from the highest pressure.

What do you think about brimonidine in the management of normal tension glaucoma? That’s normal tension glaucoma questions. Since it’s neuroprotective, especially patients with progressive glaucoma. Yeah, I think that’s brimonidine’s great in normal tension glaucoma. We didn’t really get into that but in terms of normal tension glaucoma management, you try to lower the pressure by 30% from the highest pressure. Lower threshold to recommend brimonidine since it’s got neuroprotective effects. And I still recommend prostaglandin analogs for these patients though. But yeah, lower threshold to start brimonidine, which tends to be my least favorite medication. But in these patients there is a use for it.

Please talk about the role of laser PI in these cases. Well, we pretty much, I didn’t really talk about angle closure glaucoma in which case laser peripheral iridotomy is one of the treatment modalities. There’s not really a role for laser PI in open angle glaucomas.

What is your pressure for highly myopic glaucoma patients who are pregnant? This is one of my favorite topics, management of glaucoma in pregnancy. But yeah, it’s a challenge. I have a whole other lecture on it that I give to our residents every year. But there’s a lot of contraindications to our default glaucoma medications based on very limited literature since you really can’t do studies on pregnant patients. Safe medication in pregnancy, I think it’s brimonidine, correct me if I’m wrong. But I need to pull up that lecture. But yeah, these are really challenging patients. The best thing you can do is tide over the pressure as best you can until delivery. And then perhaps consider surgical options and your options open up in the postpartum setting. Good question, that’s a whole other lecture though.

We’re at the end of the Q&A. I just want to thank you all again for your time and attention. And please don’t hesitate to reach out to me with any questions or even corrections. I will always welcome feedback. Thank you so much, again.