Beh Optometry Clinic

09/04/2026

This 15 year old patient came in to collect her spectacles on Sunday (image 1). She has asthenopia (Latin: weak eyes, English: eye stress) and headaches for the last year despite wearing spectacles, and was referred to me suggesting she has esophoria.

Phoria is a latent deviation of the eye. The eyes stay straight most of the time. It is different from tropia where the deviation is obvious. In esophoria, the affected eye will turn inwards when stresed or has difficulty to see. This can be detected clinically with the cover test (images 2a, 2b)

An eye examination revealed that she has medium uncorrected hyperopia. Her powers are:

R +1.25/0 (7th row of letters)
L +3.25/-0.50x180 (6th row)

Her spectacles made elsewhere from last year were:

R plano (7th row)
L +0.25/0 (3rd row)

There are 2 equally deterimental mechanisms to her eyes in play. First, the asthenopia and headaches. In hyperopia the retinal image is focused behind the retina (image 3a). The muscles in the ciliary body have to contract to refocus the image onto the retina (image 3b). Constant contraction caused asthenopia and headaches. Since the right and left ciliary bodies will contract together to about the same amount, when the right retinal image is focused, the left retinal image is unfocused/blurry. Over a long term, this causes amblyopia ex-anopsia (Latin: blunt eye from not seeing) in the left eye. The retina becomes inactive and blurry even when corrected.

Secondly, the ciliary body and the medial recti (plural, singular: re**us. See image 4) are controlled by the third cranial nerve (CN3). When the muscles of the ciliary body are contracting strongly all the time, the medial recti will contract in sync and pull the eyes inwards. As the left eye has a higher hyperopia, it deviates inwards further and so formed esophoria.

We always treat the root cause first, not the symptoms. By prescribing a pair of spectacles that correct the hyperopia fully, all the patient's asthenopia and headache symptoms have been eliminated. This is especially so with close work such as studying and using the computer where accommodation is required and the ciliary body contracts even more. Meanwhile, her esophoria has also reduced tremendously and there is binocular summation, where the brain combines both the right and left retinal images and amplifies them to be seen even clearer. This is an excellent sign.

The patient is instructed to wear her new spectacles at all waking hours. This will relax out the ciliary body. The hypeopia, left amblyopic eye and esophoria will need to be reassessed in 6 months' time. Usually a long standing case such as this requires several visits to be fully solved.

To be continued... 📅

29/03/2026

Always nice be appreciated. Thank you for your kind words.

12/11/2025

Please note that we close on Wednesdays and Thursdays. Thank you.

11/08/2025

This 18 year old patient came in to examine his eyes today. I noticed that he has an abnormal head posture which he said he had it for many years (see images 1a, 1b). His symptoms were general exhaustion and coordination problems like difficulty in threading a needle. However, his myopia was very low, right eye -0.50/0, left eye -0.25/0. I suspect there has to be a more sinister problem than just myopia alone.

A cover test revealed that there is significant hypophoria of the right eye, which measured to 6Δ prism diopters (images 2a, 2b).

Unlike squints, phorias are latent (hidden) deviations of the eye, so the eyes appeared straight under normal circumstances. When covered, the problem right eye will deviate to its new position, in this case downwards.

Human tolerance to vertical phorias are poor. With such a substantial deviation of 6Δ prism diopters, binocular vision is difficult to achieve. This explains the lack of depth judgement in treading needles. His brain has to constantly coordinate the six extra-ocular muscles (image 3) to keep the eyes vertically levelled to maintain fusion. This excessive and consistent muscle contractions are exhausting and when the muscles cannot continue to contract further, the patient adopted an abnormal head posture to lessen the muscle contraction and exhaustion, as this allowed the 2 retinal images to be fused easier.

To treat his hypophoria, I prescribed prisms into his spectacles. How the prisms work in general has been described in other cases before (see images 4a, 4b). The prisms hugely reduced his exhaustion and lets see if his binocular vision can improve next year. Otherwise, some binocular vision exercises may be required. My job is done.... for the time being. 😃

(to be continued)

28/07/2025

Always nice to be appreciated.... Thank you for your kind words 🥰

27/07/2025

26/07/2025

Celebrating my 10th year on Facebook. Thank you for your continuing support. I could never have made it without you. 🙏🤗🎉

25/03/2025

This 13 year old patient visited me for an eye exam today (image 1). He has congenital nystagmus and has been in my care since 6 years old. I have previously written about him:
https://www.facebook.com/behoptometryclinic/posts/pfbid033AfHev8u7G1Z4eAsNxZL8VYeuyLpfhnspuaJX6FLrs9bqDWpLFAispD6rf5S4jnrl

On a healthy retina, the highest concentration of cones resides on the macula (image 2a, 2b). Cones are light sensitive nerve cells that detects the smallest details of the image focused on the retina and they are also responsible for colour vision. An estimated 6 to 7 million cones can be found on the macula.

Congenital Nystagmus is a condition where the retina is underdeveloped and there is no functional macula. There are a number of causes of retina under-development but in this patient it is due to complications and lack of oxygen to the infant during birth.

When we look at an object, our eye will move so that the retinal image of that object is focused on the macula. This allows us to see the object clearly and is called fixation. However, when the macula is under- or undeveloped, the brain will keep moving the eye to find the best region of the retina to place the image on for the patient to see the clearest. So the eye will oscillate and this happens in nystagmus (images 3a, 3b).

Despite starting off with under-developed retinae (plural, singular: retina), years of wearing correctly prescribed spectacles seems to have forced his retinae to partially develop and organised itself so his acuity has improved, from 6/36 to 6/18 (third line to fifth line). His parents were naturally overjoyed with this news.

Every retina is precious and we do not give up. My mission continues... 💪

18/02/2025

This 16 year old patient (image 1) came in yesterday to examine his eyes. He had an amblyopic left eye a year ago and had been under treatment whilst wearing our contact lenses. This was reported earlier on:

https://www.facebook.com/behoptometryclinic/posts/pfbid03284AHjDPcfe78xHHNUuWEG8EiyB2knEozSpGyRotPYcf7EHRmGQ5isLpW4n5cf43l

The eye examination yesterday revealed that the amblyopic left eye has caught up with the right eye, both with acuity of 6/9 (7th row on the letter chart). He needs a new pair of contact lenses as his powers have changed. And all he has to do is to keep wearing our correctly prescribed contact lenses and his left eye will not be amblyopic again.

Naturally his parents were overjoyed with the news. My job is done for now... 😀

08/01/2025

This patient came in to collect his second pair of spectacles this morning. He has been wearing his first pair of spectacles prescribed by us for the last few weeks (image 1).

A month back, he was complaining of exhaustion, difficulty in maintaining focus and glare. These are symptoms of asthenopia (Latin: tired eyes). His left eye was twitching (sporadic spasms of the eye lid), which he described as being worse when his eyes were stressed. He also had previous treatments with botox to relax his muscles, but the results were temporary.

After a thorough eye exam, I found that the powers of his spectacles made elsewhere was definitely wrong, particularly for the left eye, which he described as "more blurry wearing his spectacles than without". Wrong powers caused the ciliary muscle to contract unpredictably and excessively, thus the asthenopia symptoms he experienced.

The third cranial nerve (CN3) is a motor nerve that comes out at the base of the brain (image 2). As a motor nerve, it sends electrical impulses to contract or relax muscles around the eye region. The impulses sent can be voluntary by conscious control or involuntary by a feedback from a separate sensory nerve.

I have noticed that in many patients, excessive contractions of the ciliary muscles often associate with contractions of the other muscles that the CN3 controls. This is because CN3 controls a number of muscles around the eye region, and in this case, the ciliary muscles as well as muscles of the eye lid (see image 3). By relaxing the ciliary muscles, the other muscles will also relax. After wearing our correct spectacles for a few weeks, the ciliary muscles and muscles of the lid have indeed relaxed, so the symptoms of asthenopia and twitching of the eye lid have reduced.

As we are treating the cause instead of the symptoms, now with a second pair of spectacles for computer work, we can expect further comfort and clear vision.

An article regarding lenses for computer work has been published earlier:
https://www.facebook.com/behoptometryclinic/posts/pfbid01UTrsaeJawXMpb2NUHTsB1AVbUw5HYScL7GVNghhTQSJFqJ2f3BBCC3ARTQuUkasl