Floaters- hate them, hate them

This video talks about a common and very annoying eye condition- floaters. I describe my own experience with floaters and talk about risk factors of having floaters. If you suddenly see new floaters or flashes of light, don’t delay, call you eye doctor and have your eyes checked, because 15% of cases may be associated with retinal tears and detachment. Check out my previous post about floaters: https://bostoneyeblink.com/2019/11/28… One of the risk factors of having floaters early is myopia, here is the list of videos that talk about myopia prevention and control. https://www.youtube.com/playlist?list…

Diabetic Retinopathy Screening Using Artificial Intelligence in a Primary Care Setting

https://www.umassmed.edu/ophthalmology/education/seminar-news/2022/11/juan-ding-od-phd-and-james-ledwith-md-faafp/

Diabetic retinopathy remains the number 1 cause of vision loss in working-age adults in America. Key to prevent this vision loss is early screening and detection. However, the screening rate remains low world-wide as well as in the US. For many Americans, there are several barriers to accessing quality eye care which include income, distance to the nearest clinic, and health insurance among other factors. Due to these barriers, it is important to improve the methods of screening for diabetic retinopathy, as well as the adherence to recommended follow up.  Recent studies have identified AI-based algorithms as promising tools for the screening and early identification of DR in at-risk individuals. Many different algorithms are being developed and the sensitivity and specificity of these algorithms needs to be evaluated before they can be clinically implemented. Further, there are limitations for the currently available AI that prevent them from being widely used clinically.

Our research aims to implement a novel AI that overcomes these limitations and improve diabetic retinal screening. We have partnered with the digital health company AEYE Health to test the diagnostic accuracy of a hand-held AI-assisted non-mydriatic funduscopic camera to be used in the primary care setting to screen at-risk individuals for retinal changes indicative of diabetic retinopathy. AEYE AI algorithm just received FDA clearance and we are in the final stage of implementing this technology in the primary care setting.

Freckle in the wrong place

Juan Ding, OD, PhD

Choroidal nevus is a collection of pigmented cells in the choroid, a thin layer of tissue just underneath retina. In layman’s term we often refer nevus to a ‘freckle’. Traditionally choroidal nevus is considered a benign condition. True, only about 1 in 8000 of nevi will turn into a melanoma. So the vast majority of choroidal nevus is benign. But does that mean that they don’t cause a problem? The answer is it depends. For some unfortunate people, it does cost their vision.

I recently had the pleasure of meeting a gentleman in his 60s who had vision loss in his right eye for 20+ years. The cause? A choroidal nevus that happened to be in the worst location, under the fovea. This is where our central vision is, so as a result of a nevus growing there his visual acuity was 20/400. He used to see a renowned ocular oncologist for many years and it remained stable for years, meaning it’s not turning into a melanoma. However, due to the unfortunate location of this freckle, his right eye cannot see details at all.

So given that this is chronic and stable, he was in the clinic actually complaining about something else. He has developed double vision and had to pull over while driving because of seeing two roads. Important to note, even though the nevus took away his central vision, his peripheral vision was quite normal and he relied on peripheral vision of both eyes to drive. I measured and found that he had a mild esophoric deviation, this means that his eyes are converging a little bit too much towards each other. But normally this is a small misalignment and most people compensate for this well. In his situation though, because his right eye does not see too well, it is not able to send a clear signal to the brain which then in turn is not able to feed back to both eyes to fuse the images into single vision. 

Solution to this double vision issue? A small amount of prism made it go away.

So how does this freckle that has such a big impact on his vision look? Figure 1 below is a color photo of this freckle, which was in the center of the eye.

Figure 1. Fundus image of a choroidal nevus at fovea. The arrow points to a black blob which is the nevus.

Figure 2 below shows the cross section showing how thick this freckle is.

Figure 2. Cross section view of the fovea with nevus under the retina.

So are choroidal nevi good or bad? It appears that they may not be as benign as we often believe. A retrospective medical review looked at more than 3000 eyes with stable choroidal nevi and found that of those that had nevi under the fovea, 26% developed vision loss over 15 years [1]. And it is not even that rare to have nevi under fovea, about 6% of choroidal nevus patients in this review series had their nevi right under the fovea [1]. So what is the mechanism for reduced vision if the nevi are stable? It appears that even though the size and thickness of the nevi may not change over time, they may cause edema of the retina, detachment of the RPE and thinning of the photoreceptors. If these changes occur at the fovea, then you get reduced central vision; if in the periphery as in most cases, there may be a peripheral visual field defect. It is not rare to have visual field defects from choroidal nevi; in fact, it is quite common to have field defects, ranging from 38% to 85% depending on the population analyzed [2, 3]. 

In my patient’s case, you can see that it is not even a large or thick nevus. However, it is right in the fovea and there is a thin layer of fluid between RPE and the retina, and the foveal region looks significantly thinned out (Figure 2).

It is easy to overlook choroidal nevus, because it is so commonly seen in an eye doctor’s office, and it rarely converts to melanoma. However, it is important to realize that even though it is not a cancer, it is a tumor all the same. It is not just an inert growth under the retina, but rather can often slowly but actively cause changes to the retina, affecting its function. If it happens to be under the fovea, significant vision loss can happen to patients. 

References

[1] Shields CL, Furuta M, Mashayekhi A, et al. Visual Acuity in 3422 Consecutive Eyes With Choroidal Nevus. Arch Ophthalmol. 2007;125(11):1501–1507. doi:10.1001/archopht.125.11.1501

[2] Tamler  EMaumenee  AE A clinical study of choroidal nevi.  AMA Arch Ophthalmol 1959;62 (2) 196- 202

[3] Flindall  RJDrance  SM Visual field studies of benign choroidal melanomata.  Arch Ophthalmol 1969;81 (1) 41- 44

Should you take antibiotics with that bump on your eyelid?


Eyelid bumps, sometimes called styes, are very common. They are usually red, sometimes painful, and sometimes will stay there for months. Sometimes these bumps keep coming back. There are two major types of eyelid bumps, one called hordeolum and the other chalazion. Both are caused by blocked oil glands in the eyelid, called meibomian glands. This gland secretes oil through an opening on the eyelid margin (that’s the thin edge at the base of the eye lashes). This oil is really important to keep our tears in good quality (refer to some of my previous posts on meibomian gland and dry eye). When the opening is blocked, the oil backs up inside the gland, and forms a bump. In terms of the hordeolum, this oil content is infected by our normal skin bacterial flora, so this is technically an infection, but it’s often self-limited. In terms of the chalazion, this content undergoes an inflammatory process but not infection. This is one of the reasons that the hordeolum is often painful and chalazion is not.

Regardless, given similar etiology, the treatment is to open up the blocked gland and let the oil flow again. And one effective way to do this is to apply a warm compress on the bump, this allows the content to soften and drain more easily.

However, doctors sometimes prescribe antibiotics, be it an oral pill, or an eye drop or ointment. So the question is: is it necessary to take antibiotics for hordeolum or chalazion?

There is a recent research [1] that retrospectively looked at more than 2,712 cases of these two conditions, some of these were treated with warm compress alone, some with antibiotics alone, and some with warm compress as well as antibiotics. The final outcome shows that all 3 treatments led to a similar rate of resolution, over 70% for chalazion and over 90% for hordeolum. This shows that additional topic antibiotic drops/ointment or oral antibiotics do not really give additional benefit. Warm compress alone works just as well. It’s interesting that antibiotics alone also have a good success rate, though only 1% of patients were treated by this method. 

The limitation is that this is a retrospective study. There is a randomized controlled trial looking at chalazion and found similar outcome: antibiotics do not give additional benefit in addition to warm compress [2].

Given the rampant antibiotic resistance these days, I think it’s reasonable to apply just warm compress and not start antibiotics automatically for every eyelid bump.

References: 

[1] Alsoudi, Amer F. B.S.; Ton, Lauren B.S.; Ashraf, Davin C. M.D.; Idowu, Oluwatobi O. M.D.; Kong, Alan W. B.S.; Wang, Linyan M.D.; Kersten, Robert C. M.D.; Winn, Bryan J. M.D.; Grob, Seanna R. M.D.; Vagefi, M. Reza M.D. Efficacy of Care and Antibiotic Use for Chalazia and Hordeola, Eye & Contact Lens: Science & Clinical Practice: November 8, 2021 – Volume – Issue – doi: 10.1097/ICL.0000000000000859

[2] Wu AY, Gervasio KA, Gergoudis KN, Wei C, Oestreicher JH, Harvey JT. Conservative therapy for chalazia: is it really effective? Acta Ophthalmol. 2018 Jun;96(4):e503-e509. doi: 10.1111/aos.13675. Epub 2018 Jan 16. PMID: 29338124; PMCID: PMC6047938.

Normative database of axial length in children

This article is for eye doctors who use axial length routinely in their myopia control clinic, and certain parents who are curious and/or obsessed with the numbers of their children’s eyes (trust me, I do encounter these parents weekly).

Briefly, axial length is the length of the eyeball, which grows throughout the first 18 years of a person’s life. It is normal for the eyes to grow longer over time until it stabilizes at adulthood. But the growth can be accelerated resulting in long axial length in myopia. Therefore in many eye doctors’ offices, this value is measured to monitor myopia development and record whether myopia control is successful with a given intervention.

Understandably, it is important to have a normative database to evaluate whether a given child’s axial length is normal. Basically, there have been quite a few published articles on typical axial lengths of children of various ages. I have put together data from two recent studies that encompass ages from 3 months to 18 years below. The mean values for a given age are listed, as well as standard deviation. Table 1 is from Florida, USA, on 165 American children (Miami study) [1] and table 2 is from Shanghai, China, on 14,127 Chinese children (Shanghai study) [2]. Obviously the 2nd study is a much larger scale, and I really am very excited about this very new data. The first study, though with much fewer subjects, is quite remarkable as well in my opinion, as it examined kids as early as 3 months, understandably not easy to do and not many other studies were able to look at this age group. So I am keeping these two tables as a reference for my own patients. 

For those who are more visual, Figure 1 and Figure 2 are these numbers plotted in graphs.

Table 1. Axial length of 3 month to 7 years old children (Miami study)

Table 2. Axial length of 4 to 18 years old children (Shanghai study)

Figure 1. Axial length mean (solid line) and 95% confidence interval (dotted lines) in 3 month to 7 years old children (Miami study).

Figure 2. Axial length ranges in 4 to 18 years old children (Shanghai study).

A few things to keep in mind from these data. 

First, these are from two distinct populations. The 3 month to 7 years old study group (Miami study) were children from Miami, FL. No ethnic background information was given in the paper, but one can assume it could be typical from that area. The 4 to 18 years old study group (2nd Shanghai study) were Chinese children. It is well known that Chinese children have longer axial lengths than Caucasions and African descents (and more prevalent myopia rates unfortunately), so we certainly cannot assume that this is inclusive of all possible scenarios. 

Second, you can see that for any given age, there is a wide range of axial lengths in both studies. This tells us that normal is a range, NOT a single number. Do NOT compare the number of your child to your neighbor’s kids. This is not a competition. Also, it has been demonstrated again and again that it is the rate of axial length growth, rather than the absolute number, that better predicts myopia progression. Do not get anxious over one measurement. Monitor the axial length over time to find the trend. 

Lastly, I would still stress that while it is great that we have a normative database for axial length, it is still the gold standard to perform cycloplegic refraction to accurately assess a child’s true refractive error. Axial length measurement is a powerful tool, but it does not and cannot replace cycloplegic refraction.

References:

[1] Miami study: Bach A, Villegas VM, Gold AS, Shi W, Murray TG. Axial length development in children. Int J Ophthalmol. 2019;12(5):815-819. Published 2019 May 18. doi:10.18240/ijo.2019.05.18

[2] Shanghai study: He X, Sankaridurg P, Naduvilath T, Wang J, Xiong S, Weng R, Du L, Chen J, Zou H, Xu X. Normative data and percentile curves for axial length and axial length/corneal curvature in Chinese children and adolescents aged 4-18 years. Br J Ophthalmol. 2021 Sep 16:bjophthalmol-2021-319431. doi: 10.1136/bjophthalmol-2021-319431. Epub ahead of print. PMID: 34531198.

新冠疫情下的儿童近视讲座(Myopia Control in COVID-19; Language: Mandarin)

Please join us for a scheduled Zoom meeting.

Topic: 新冠疫情下的儿童近视讲座(Myopia Control in COVID-19; Language: Mandarin)
Time: May 23, 2020 08:00 PM Eastern Time (US and Canada)
Speaker: Dr. Yueran Yan
Meeting Capacity: 100 (first come, first served)

Join Zoom Meeting
https://us04web.zoom.us/j/73089566870?pwd=ZTlnQkY3QUVId002d0p3cTJWcUdsUT09

Meeting ID: 730 8956 6870
Password: 6qC3i8