Losing half of vision is no small matter

Juan Ding, OD, PhD

Today I will tell the story of a patient who lost half of his vision. 

Disclaimer: patient’s name is an alias, but the case is real.

I saw John once a year for a few years, monitoring his glaucoma suspicion. Glaucoma suspicion simply means that one’s suspected to have, but does not really have glaucoma yet. He had good vision in general, but usually had many complaints about his vision, mostly that he had to use glasses which he never needed to wear before. 

Once he splashed some chemicals in his right eye while doing house work, and saw my colleagues multiple times while I was on vacation. According to the medical record, the chemical burn had resolved. He came to see me shortly after that.  

‘Doc, I cannot see with my right eye’. My thought was, maybe he was having scars on the cornea. But his cornea looked clear with only a faint scar in the periphery that could not cause vision loss. What’s also interesting was that both his eyes had similar vision. But he insisted that since the chemical splash, he could not see well in the right eye. Could the chemical have reached the back of the eye and caused retinal or optic nerve damage? With a dilated exam, as well as photos of the optic nerve, everything still looked as good as before. There was no apparent retinal or nerve damage.

So I ordered a visual field test. This test examines the periphery vision rather than central vision. I have a couple of his results from previous glaucoma testing, and one looked like Figure 1 A. The dark spots mean vision is less sensitive in that region. So in this graph (Figure 1A), there are only a few minor defects in both eyes.

Figure 1. Gray scale graphs representing visual field results. Each eye was tested separately and darker the spot means worse vision in that particular region. Copyright: Boston Eye Blink

When I saw his visual field results on that day (Figure 1B), I knew the worst had happened. I immediately called him and said, ‘John, you have to go to the emergency room right now.’ 

 As you can see now he had lost a half of vision on the right side, both for right and left eyes. So while he was complaining of not seeing in the right eye, he was actually not seeing on the right side.

This is called a hemianopsia, which means ‘half no see’, or losing vision in one half of the visual field. Vision with hemianopsia is somewhat depicted in Figure 2. This is not an eye problem. This is a brain problem. Specifically, there is a problem in the left side of the occipital cortex, a part of the brain that gets signals from the eye. 

Figure 2. Simulation of vision with right-sided hemianopsia. Everything to the right side of the visual field appears gray out or dark.

You see, our eyes ‘see’ things, but it’s really the brain that perceives the action of ‘seeing’ and gives meaning to it. When the brain suffers damage, both eyes will lose vision on the same side. But often patients will perceive the right side of vision loss as vision loss in the right eye.

And one of the most common causes of such brain damage is a stroke. Especially in a patient like John who has high blood pressure and heart problems. John had a history of congestive heart failure and had a pacemaker. 

‘But I am not having a stroke. I feel fine.’ John said. I asked for several other symptoms, such as weakness or numbness on one side of the body, slurred speech, difficulty walking, and so on. He denied all of it. 

He had been to the ED before, it was not a pleasant experience. He sometimes waited for 8 hours and just left before being seen. 

I get that. But this time it is different. Hemianopsia can be the only symptom of a stroke. I managed to convince him to go that day. I also called his PCP to check up on him to manage his high blood pressure.

In the subsequent weeks, he developed other stroke symptoms including weakness in his leg. 

I saw John again after 2 months. Needless to say, John was very distressed about his vision problem. He’s bumping into things and felt unsafe to drive. He complained about the long wait in the ED. The head CT scan did not reveal much, but he could not do the MRI due to his pacemaker. His visual field looked like in Figure 1C above. Well, not much improvement, perhaps a little worse even. 

Research has shown that many stroke patients suffering hemianopsia recover partial or full vision within 6 weeks. He’s clearly not in the lucky team. If they don’t show any improvement by 6 months, it’s unlikely they will ever have improvement. About ⅓ of all stroke patients with hemianopsia will never recover or improve. I have seen some patients just like that, they permanently lose half of their visual field after a stroke.

I asked John to come back in 4 months, which will be 6 months post stroke, to check again.

This time his visual field looks like above (Figure 1D). It looked like he had a full recovery! I was relieved and felt very happy for him. I asked him, ‘how do you feel about your vision?’ I was surprised to hear him say, ‘Terrible. It’s getting worse.’ 

‘How come? Your visual field is much better. You are basically normal now.’

‘Oh THAT,’ he said, ‘yes that’s better, I can drive again. But my glasses are broken and I really cannot see anything for reading.’

You will be happy to learn that John now has new glasses and is seeing well. He’s seeing his PCP as well as his cardiologist to manage his high blood pressure. 

Crocodile tears

A man in his 30s came in because he saw flashes of light for 20 minutes two days ago.

He was having very blurry vision and could not focus as well at the time, but it all resolved on its own and he remained symptom-free. After a thorough dilated exam I determined that his retinas were completely normal and his symptoms were most likely from ocular migraine. 

Then he brought up something else completely unrelated. For three years now whenever he ate something his right eye would tear up and it’s always only the right eye. That eye was not red, itchy or painful, it simply teared up a bit. 

He did not have dry eye. And both of his eyes were white and quiet with no sign of tearing at the time. His description sounded almost like crocodile tear syndrome. This is a very rare condition where the nerve that supplies the salivary gland somehow also goes to innovate the lacrimal gland which secretes tears. When he’s having a meal his salivary gland gets a signal to start secreting saliva, and that cross talks to his lacrimal gland which makes his right eye tear up. This often happens after nerve injury when the nerve tries to repair itself and makes an inadvertent mistake. This is called aberrant nerve regeneration. But he denies any facial or head injury. He reports to be completely healthy and taking no medication. 

The treatment for crocodile tear syndrome is to inject Botox into the lacrimal gland so that a part of the gland doesn’t work and therefore not too many tears are produced. In his case this doesn’t really bother him so we will just monitor.

Fake membrane

A man in his late 40s came in with blood shot and swollen eyes. 5 days ago while in the gym he rubbed his eyes after cleansers still on his hands. Since then each day both of his eyes were feeling worse with foreign body sensation, itchiness, pain and discharge. He went to urgent care 2 days ago, was given antibiotic drops and ointment, but felt it’s not helping. His conjunctiva (white part of eyes) were the most swollen that I had seen. Unfortunately I did not take a photo, but found one on the internet that quite resembled his eyes at the time as shown below.

Image 1. Conjunctiva chemosis (swollen conjunctiva). Image from https://images.app.goo.gl/V48FJXf32i9gdeov5

Cornea (black part of the eye) was clear. At the time I thought this was toxic/allergic conjunctivitis, so prescribed a steroid drop to use 4 times a day for 7 days. 

A week later, he came back, reporting improved symptoms (pain 3/10 from 5/10 previously), but still lots of discharge. This time, the swelling was gone, the redness almost resolved, but when I pulled his eyelid down, there were white pseudomembranes (fake membranes) in both eyes, more in one eye than the other. Below is again from internet, showing similar to what I saw.

Image 2. Conjunctival pseudomembrane, a white membrane developing inside the eyelid. Image from https://images.app.goo.gl/bUz4K3c7xtfaDYaYA

Now this made me rethink the diagnosis. Pseudomembranes are often seen in infectious conjunctivitis caused by nasty bugs such as Corynebacterium diphtheriae, Neisseria gonorrhoeae, Streptococcus pyogenes and adenoviruses, some of these are highly contagious. I asked whether anyone else in the household developed pink eyes, and he said no. He had no systemic symptoms or swollen lymph nodes, which were a good sign. Pseudomembranes can also be caused by toxic and allergic agents, and even foreign bodies [reference 1]. So at this point I was still going with allergic conjunctivitis, but these other infectious causes were now on the back of my mind, making me uneasy. So I stopped the steroid drops and switched to an antibiotic/steroid combo drop, as well as adding an antibiotic ointment at night. Of course, the pseudomembrane had to be removed otherwise he would not get better.

1 week later he came back, this time he’s much better, no discomfort, not much discharge, no swelling or redness. Exam revealed residual tiny papillae, and the membranes were gone! 

To summarize, pseudomembranes can be caused by infections, toxins, foreign bodies or allergies, and to treat it the underlying cause needs to be addressed, and pseudomembranes need to be removed promptly.


[1] Ho D, Lim S, Kim Teck Y. Pseudomembranous Conjunctivitis: A Possible Conjunctival Foreign Body Aetiology. Cureus. 2020;12(5):e8176. Published 2020 May 18. doi:10.7759/cureus.8176

Gray floater in an elderly lady

Floaters can be so common, yet not all floaters are the same. Here is another example.

An 84 year old nice lady came for an urgent visit as she started noticing a greenish gray floater in the right eye for 1 week. She did not notice any flashes. Her right eye saw 20/400 with no improvement with pinhole (this usually means that vision cannot be improved with glasses). Her left eye was able to see 20/30.

It’s impressive that she had not had cataract surgery yet, and only had a moderate amount of cataract. One look at her macula in the right eye revealed why she saw this gray ‘floater’. There is a blob of blood there as shown in images below. 

Figure 1. New membrane (arrow head) and bleeding (***) in the macula of the right eye.

The other eye only had mild drusens in the macula, indicating early age-related macular degeneration.

So this may be a case of very asymmetrical presentation of AMD with the right eye affected by wet AMD with acute bleeding and vision loss, and left eye only affected by mild dry AMD.

I referred her to a retinal specialist for treatment.

See my other articles on “floaters” and related eye phenomena.



Where is the pit?

Juan Ding, OD, PhD

Our central vision is seen by a structure called macula in the retina, and the center of the macula is called a fovea. Normally there is a pit dipping down at fovea as shown in Figure 1 below, and this is important for normal central vision.

Figure 1. Normal foveal pit indicated by the arrow.

Yesterday I saw a kid that had abnormal, or under-developed fovea.

This 6 year old boy came with his foster mother. He had fair skin, blond hair and was very light-sensitive. Mom never noticed anything abnormal, but he failed the vision test at his pediatrician’s office and that’s why they came here. 

His vision was 20/50 and 20/40, normal eye alignment, minimum refractive error, but after cycloplegia about +4.00 of hyperopia. At any rate, this hyperopia should not cause reduced vision at his age. So what can it be?

Interestingly when I looked at his retina I could not see a foveal reflex. And the retina was really light in terms of pigment. I attempted OCT and with some luck, managed to get photos from this well-behaved 6 year-old. It is apparent that his macula is lacking a normal foveal pit (Figure 2, right and left eye, respectively). 

Figure 2. Lack of a foveal pit in right and left retinas in our patient.

I gave this a tentative diagnosis of ‘fovea hypoplasia’. This condition can be seen in ocular albinism (lack of melanin) or aniridia (lack of iris), or it can happen as an isolated condition. He has normal eye structures everywhere else. Combined with a blonde fundus and extremely fair skin, I do suspect albinism. But he has no nystagmus, and vision is very good if he does have albinism. Since he was adopted, we do not know much about his family history. Mom adopted him while he was 18 months, and noted good health and normal developmental milestones up to now.

Given moderate to high hyperopia, I gave him a prescription of reading glasses. I referred him to his pediatrician to consider genetic testing.


Juan Ding, OD, PhD

This case is from one of my favorite patients. He first came to me as a referral from his ENT (ear, nose and throat) doctor, because he complained about dry eyes since his facial nerve palsy on the right side. His ENT doctor was not the one to diagnose facial nerve palsy of course, but since he was undergoing several sinus surgeries he happened to mention this during one of the visits. 

In his initial eye visit, I noticed that his vision was not able to be corrected to 20/20 by glasses, and he had a large amount of astigmatism. Retinoscopy showed scissor shaped light reflex, and slit lamp exam showed steepening cornea with prominent nerves and the right cornea actually had a mild scar. Corneal topography later confirmed keratoconus in both eyes, more so in the right eye.

Keratoconus literally means a corneal cone. Cornea is the front transparent layer of our eyes, and it is usually a regularly shaped dome like in the image on the left (Figure 1). But in keratoconus, the cornea gradually becomes thinner and thinner, and bulging more and more like in the image on the right. Because now the cornea is irregular, vision is blurry, even with glasses often still not good, since glasses do not correct this irregular surface of the cornea. Even regular soft contact lenses will not do much in this case because the soft lens material will just drape over the irregular cornea and still showing the irregular optics.

Figure 1. Normal cornea and cornea with keratoconus. Image from www.allaboutvision.com

Fortunately certain rigid contact lenses called rigid gas permeable (RGP) lenses can correct vision. These are stiff and can mask the irregularity of a keratoconus cornea. These are typically small, and often very uncomfortable especially in the beginning while the hard lens rubs against the surface of the eye and the eyelid.

Another type of lens to correct vision for keratoconus is a scleral lens (Figure 2). This is a large lens that sits on the white part of the eye called sclera, therefore causing minimum discomfort to the eye, and it corrects vision because the lens vaults over the irregular cornea to mask its imperfection.

Figure 2. How scleral lens corrects vision in keratoconus. Image from https://visualeyesboca.com/scleral-lenses/

Back to my patient, I initially fitted him with special RGP lenses designed for keratoconus, but due to advanced bulging, these lenses were unstable on the eyes and often popped out when he moved his eyes around or blinked. I then fitted him with Jupiter scleral lenses. These are very simple and easy on the patients as they are a relatively small scleral lens and easier to insert for beginners. However, in his case, the fitting was not ideal because the edge of the cornea kept being pressed close to the back surface of the lens. This is not good in scleral lens fitting, as it may not leave enough space for the cornea to breathe. I then switched to BostonSight scleral lens design, which is larger and more easily vaults over the entire cornea. He was very happy about his vision, with the right eye seeing 20/25 and left eye seeing 20/20. He told me that he ‘hasn’t seen this well since 16’- that was probably when he started developing keratoconus. He’s now in his early 40s, and this was the first time he heard of keratoconus. 

Keratoconus is a condition that affects about 1 in 2,000 individuals. It usually starts in teenage years or early 20s, but can happen as early as 8 or 9 years of age. It tends to get progressively worse until stabilization in the mid 30s. There is often a family history, but not always. Both eyes tend to be affected, though one eye may be much worse than the other. We do not know the cause of the disease, but one modifiable risk factor is rubbing of eyes. So I always ask patients not to rub eyes. While it is progressing, an effective treatment called corneal cross linking can stabilize the cornea and halt the worsening of the condition. This procedure is typically done by a corneal specialist. Once cornea is stable, these special contact lenses such as RGPs or scleral lenses can often help patients to see what they used to be able to. Any keratoconus patient should have at least two types of eye doctors, one a corneal specialist, and one an optometrist who fits specialty contact lenses for keratoconus.

I feel like there are rocks in my eyes

by Juan Ding, OD, PhD

Today I had an urgent visit from an established patient. She’s in her early 50s, and has a medical history of high blood pressure, anxiety and depression. Regarding her eye history, she had narrow angles, which means she is at risk of developing a type of glaucoma (angle closure glaucoma), and for that she had laser peripheral iridotomy (LPI) before. This procedure allows fluid to communicate in the front chamber of the eye, preventing closure of the drainage system of the eye (the angle) thereby preventing high eye pressure from happening which can cause glaucoma. 

She was very anxious because since she started a new antidepressant, desvenlafaxine (Pristiq), 3 months ago, she started feeling like there were rocks in her eyes, blurry vision, more migraine and her blood pressure went up. Desvenlafaxine is a serotonin-norepinephrine reuptake inhibitor (SNRI), and it may cause blurry vision and angle closure glaucoma. She was very much aware of her narrow angles and worried that it’s causing glaucoma in her eyes. On her psychiatrist and pharmacist’s recommendation, she stopped the medication 2 days ago, but was now suffering from serotonin withdrawal syndrome. Her psychiatrist prescribed prozac as a transition drug, but wanted to make sure her eye pressure was not elevated. She had the medication in her car, and if the test was normal she would go and have her first dose. If not, she would not be able to start this new medication.

Fortunately, eye exam showed that she had normal eye pressure, and that her LPI was still working and her angles were open. So she was cleared to go on with another antidepressant.

But her eyes were dry, and this explained her sensation of ‘rocks’ in her eyes. She did try refresh artificial tears and felt it immediately helped her symptoms. I advised her that she could actually use these artificial tears regularly, up to 4 times daily, as long as she’s feeling the dry eye symptoms.

All too often, antidepressants and other medications cause dry eye. It’s not only uncomfortable, in some cases, causing extreme eye irritation in patients, who are anxious and depressed to begin with; but it can also cause blurry vision because of disrupted tear film. Anyone taking antidepressant is at risk of developing dry eye, and may try some OTC remedies first, like artificial tears, before visiting their eye doctors. Glaucoma is a much more rare side effect, but anyone with a history of narrow angles or glaucoma suspicion should be very careful- it’s best if they visit eye doctors routinely while on certain antidepressants. In severe cases of recalcitrant dry eye and/or glaucoma, an alternative medication may need to be considered. 

I see fluid coming up in my eye

Another case by Juan Ding, OD PhD

A young gentleman in his 20s came in complaining of poor vision in his left eye which worsened for the past 2 weeks, particularly that it bothered him to see ‘fluid seeping up’ in his left eye vision happening a few times in the past two weeks. No it is not seeing fluid in his left eye in a mirror, it is seeing that with his left eye.

He grew up in a middle east country, had congenital cataract and cataract surgery both eyes. When he was a young kid, he unfortunately had an injury to his left eye that made him completely blind in that eye. He wears a prosthetic shell in the right eye. After removing the shell, it is obvious that this eye has gone – it is withered (phthisis bulbi), with a white membrane (pannus) over the entire cornea. Importantly, there is no sign of infection in this eye, and it does not hurt.

The left eye had only hand motion vision, meaning he can see hand moving in front of his eye but no details. This eye also shows back and forth shaking (nystagmus), which sometimes happens with poor vision from a very early age. Eye pressure is 10, which is normal. There are a lot of cells (4+) in the anterior chamber, which means very severe inflammation. The pupil is irregular and completely stuck to the artificial lens behind (posterior synechiae). The dilation drops could not dilate the pupil at all, so I was not able to see anything behind. Additionally, there appears to be a white membrane on the artificial lens, further blocking any view to the back. Unfortunately in my small eye clinic we do not have B scan to check if there is any retinal detachment.

Further questioning did not yield much more useful information. The patient was aware that he did not see well out of the left eye, but he did not know why, and could not produce any previous medical record.

Given the finding, I prescribed steroid drops for inflammation, and atropine, a strong dilating drop to break the sticky pupil. I made an appointment for him to see our uveitis specialist in 2 weeks, hopefully the pupil will be dilated then for her to see.

The patient walked in to see another eye doctor of our department 6 days later, complaining that his sx did not improve with the drops. In this visit, his eye pressure went up to 29, which was attributed to steroid response. He was given timolol to lower eye pressure

One day later he walked in again, complaining seeing everything white with the dilating drops. His eye pressure in the left eye now became 5. This time the access doctor happened to be the uveitis specialist. She found still the same amount of inflammation that I saw, and found funnel retinal detachment (this is retina detached almost entirely except for the optic nerve head position, causing a funnel shape on ultrasound, as shown below) on B scan. She increased steroid dosage and referred him to our retinal surgeon.

funnel RD from web

image: Ultrasound scan showing a funnel retinal detachment (source: https://imagebank.asrs.org/file/1431/open-funnel-retinal-detachment). This is not my patient.


Weeks later, as I checked back the medical record to see how he’s doing. I found out that he went to Mass Eye and Ear (MEEI) in Boston. From their notes, it appears that he used to see eye doctors there, diagnosed with chronic funnel retinal detachment in 2015, but lost to follow up subsequently.

So the mystery is solved. His chronic retinal detachment is most likely the cause of his uveitis (eye inflammation), and bleeding in the vitreous (found on B scan at MEEI) would be the cause of worsening vision recently, and seeing ‘fluid going up’ in his vision.

Retinal surgeons at MEEI plan to do surgery for him, though the prognosis for vision is poor due to chronic macula off retinal detachment.

It is sad to see a young person who already is blind in one eye to lose vision in the other eye. Infants need to be screened for conditions such as congenital cataract. It is already late if you notice nystagmus. Fortunately this is done routinely in newborns and well visits by pediatricians. Eye injuries should be prevented, especially for boys. And if you already have a serious eye condition, like retinal detachment, please follow up with your eye doctor.

Seeing a bluish green spot in the right eye

By Juan Ding, OD, PhD

Case of the day series

A college student walked in for an urgent visit for seeing a bluish green spot in her right eye constantly for 1 week. She went to Colorado last week and did a lot of hiking, taking many photos everyday, enjoying nature. On the last day of the trip, she started seeing a bluish green spot in the right eye, more obvious in the bright background, but it’s there even after closing eyes. She was very scared and went to the local ER, where they did an ultrasound of the eye and found no retinal detachment, but did not know what’s wrong. After getting back to MA, she could not get an appointment with her regular eye doctor, and being the holiday season it’s busy everywhere. Fortunately her PCP at Umass directed her to our open access clinic.

Her vision is normal, 20/20 in each eye. Everything from the front to the back of both eyes are normal. I found no retinal detachment, not even vitreous floaters.

She asked, “Am I crazy? Am I imagining things?”

What do you do next?

Knowing too well that clinical exam has its limitations, I asked her to take an OCT photo. This is looking at the retina in cross sections, like virtually dissection the retina. There is a very small dot in the right eye, just temporal to the fovea, where the photoreceptor outer segment now shows a small defect (Figure 1). Amsler grid shows a matching scotoma nasal to the fixation.

solar retinopathy

Figure 1. OCT of macula cross section. Red arrow points to the lesion at the photoreceptor outer segment level (ellipsoid zone).


So I told her that she’s not crazy, a retinal lesion really exists to perfectly account for her seeing the spot.

But what caused it?

Solar retinopathy is the first thing that comes to mind. She denied looking directly at the sun. also denied exposure to laser including laser pen or in a science project. Then she mentioned that during daily hiking, she did spend a lot of time looking at camera screen which could be very bright due to reflecting sunlight. This seems to be the most plausible explanation for now.

I told her that solar retinopathy may get well on its own in weeks to months. It may also be irreversible. At any rate, there is no treatment for this. So we will monitor again in a few months.

What, an eye AND ear problem?

by Juan Ding, OD, PhD

A 70 year old Asian male complained of eye pain and redness in both eyes, in addition, left ear was swollen and mildly painful, and not hearing too well. He was found to have episcleritis (inflammation of a deeper layer in the white part of the eye) in both eyes and iritis (inflammation of the iris) in the left eye. Combination of these symptoms are suspicious of a condition called relapsing polychondritis (RP). This is an autoimmune disease that targets the cartilage tissue of the body, for example the ear, nose, and the trachea. Eye inflammation can also occur. Since it’s autoimmune in nature, the treatment would be anti-inflammatory, using for example corticosteroids and non-steroidal antiinflammatory drugs (NSAIDs). If necessary, some disease modifying agent such as methotrexate can also be used. He was started on naproxen 500 mg twice daily, as well as an NSAID and steroid eye drops, and his symptoms went away. So in the end he did not need to take methotrexate.

He also had a hx of latent tuberculosis (TB). latent TB means a person has been infected with tuberculosis in the past, but does not show any active sign of disease, such as coughing, fever and night sweats. However, latent TB can cause inflammation in any part of the eye, including the episclera and the iris. So in this case, he is also seeing an infectious disease specialist. Since his eye and ear symptoms resolved on NSAIDs and steroids, it was thought that TB was not the cause, but he was treated with isoniazid for 9 months for latent TB without incidence.

Lastly, although RP frequently causes ears to be red and swollen, it does not typically cause hearing loss. His hearing loss was considered to be another cause. He was treated for 1 month after onset of hearing loss (and ear pain) for a viral etiology with valtrex and prednisone, but did not recover hearing.

So the moral of this case is, if they have inflammation of both eyes and ears, don’t just treat the eye, and think a common underlying etiology.

5 years later, patient came back to see me, his eyes are quiet, as his ears. He does report occasional eye sensation reminiscent of past iritis, but always responds well to the prednisolone drops that he’s instructed to use as needed which he used a few times a month. He is currently not taking any medications for RP and doing well. I asked him to come back in 3 months to check eye pressure and check eye inflammation, and that if a flare up happens come right back. Hopefully the relapsing nature of this disease will not recur.