Thursday, December 31, 2009

Happy New Year !!

A Happy New Year to All !!

(When you pop-open the champagne bottle, make sure the cork does not hit anyone in the eye .)

Monday, December 14, 2009

10.9 Perfect parking

So you have trouble reverse parallel park your car? Relax, Prof Simon Blackburn of University of London's Royal Holloway College comes to rescue (The Telegraph 12/11/2009). He has devised a formula so you'll know when to turn the steering wheel at the precise moments:

Gee, and we have all thought that parallel parking is all about eye-hand-brain coordination.

Friday, November 13, 2009

10.8 Peripheral hyperopic defocus

Recently, some diligent researchers have come up with a novel explanation of myopia progression in the human, i.e., the "peripheral hyperopic defocus".

In plain English, it means when you wear glasses to correct nearsightedness or more accurately the central vision, the side vision is actually still fuzzy with the clear focal points behind the eye (or being hyperopic, i.e., farsighted, by definition). This is illustrated in the picture here, in which the white arc behind the eye is the hyperopic focus. It is this blurriness at the retinal level that seems to cause the eyeball to grow or "elongate" in the anterior-posterior sense. Not only in the myopic eyes, potential myopic eyes also have the more prolate eyeball shape. So it would appear that the shape of the eyeball is predictive of myopia formation and progression.

With the new information,
(1) the instrument makers can develop new refractive devices;
(2) lens makers can design new spectacle and contact lenses;
(3) the doctors will have new myopia managing regimens to contemplate;
(4) the biochemists will propose and test new projects on the development of posterior sclera/choroid during myopization; and
(5) the drug makers can look into more targeted posterior pole growth inhibitors.

In other words, a whole new enterprise unveils right before our eyes. Naturally it remains to be seen if this defocus theory ultimately proves to be true.

Tuesday, October 13, 2009

10.7 Gordon Brown's eyes

Have you ever noticed that Mr Brown's left eye is slightly recessed and is in a down and out position?

He has lost his vision in the left eye from retinal detachment - after being kicked in the head while playing rugby at age 16. Several attempts at repairing this eye had failed. When the right eye started to show the same symptoms and signs of RD two years later, the re-attachment was quite successful.

A routine annual eye exam on Oct 10 reveals that Mr Brown's right eye has two small retinal tears. For now, ophthalmologists at Moorfield Hospital where Mr Brown was seen have decided to continue observation rather than perform an operation. Presumably, 3-7% of Brits walk around unaware of retinal tears in their eyes. Mr Brown insists that his eye sight has not deteriorated; although he does read texts with large prints.

Quite a few take-home lessons here:

(1) contrary to common belief, low vision in fact does not affect a person's capabilities;
(2) the need for regular eye exams is clear - once every two years as a matter of principle, once every year when necessary;
(3) not all retinal tears must be patched;
(4) RD from head trauma is not uncommon - with long latency as well; and most important,
(5) retinal tears do not affect central vision - patients must instead pay attention to appearance of photopsia and floaters.

Wednesday, October 7, 2009

10.6 Reading glasses and bank robbery

Guess what, now reading glasses are an accessory for committing a crime:

News from BROCKTON, MA, USA - Police are looking for a man who robbed a bank Monday (Oct 5, 2009) morning in Brockton.

The suspect, who was wearing reading glasses and a Red Sox hat, passed a note to the Community Bank teller demanding money, police said. The man fled from the Main Street bank in an unknown direction after taking money.

Police say the suspect was wearing a beige pullover, blue jeans and work boots. Anyone with information about this person is asked to call Brockton police at 1-(508)-941-0234.

Let's see, a male Caucasian with a pair of half-eyes suggesting he is 42 years-old with 20/20 distant vision. The glasses are apparently OTC, purchased for US$15 from a local drug store, probably one of the CVS Pharmacies. Most likely, these glasses are made with +1.25 to +1.50D lenses to be used for reading comfortably at 16 inches, if we know the height of the counter top at the bank, this robber's body height can be quickly estimated. On the other hand, the Boston Red Sox cap is not helpful, almost everybody has one.

Forensic optics can be fun, huh?

Thursday, August 13, 2009

10.5 LCA repair

After 2 years, the preliminary results of LCA (Leber congenital amaurosis) gene therapy are in [Aug 12, 2009].

This study is still ongoing at U of FL and UPenn (and other universities). The participants are a woman and two men between the ages of 21 and 24. After 12 months, the safety is maintained. More important is this:

"The tiny portions of the patients’ retinas that received gene therapy [RPE65] experienced restored function up to 1,000-fold during the day and 63,000-fold at night."

In other words, the patients have developed a preferential retinal locus at the injected (treated) area. The visual acuity will depend on the photoreceptor density, among other issues. And the field size will necessarily be limited to the locus. Still, it is a giant leap forward.

Let's hope this study continues to be successful.

Thursday, July 30, 2009

10.4 Blue-eyed rodent

Researchers at Univ of Rochester have discovered that Brilliant Blue G, a food dye, when injected IV can prevent secondary neuronal damages caused by an excess release of ATP into the spinal injury site.

The injection works only if it is done within 15 min after the injury and the skin turns blue for a while as a result.

The more interesting to us is the eyes now also appear blue (right). The pink hue of the paws, ears, nose, and the eyes (top left) is typical of the lack of pigmentation in this type of rats allowing the vascularity to show through.

Presumably then, a fair-skinned person, after consuming a large quantity of blue M&Ms, may develop dark blue eyes even if only briefly. The blue skin? We refer you to Star Trek (2009), Uhura's roomate (and Kirk's date) for more details.

Wednesday, June 24, 2009

10.3 Target: one million cases of cataracts

This is a news report on June 24, 2009:

来源:荆楚网 (楚天都市报 陈媛 田静欣 高翔 向清)


Partial translation: "Hubei Province will soon institute a program, Cataract Vision Restoration for the Poor, and about 1 million patients will benefit. This is a 3-year program and for the current year, 9,475 patients will enjoy a $800 (about USD 100) discount for the surgery... It is estimated that there are 12.4 million blind in China. Of them, 6.99 million are cataract cases and 15% cannot afford to pay for the surgery [hence this program]."

Certainly a step in the right direction.

Tuesday, June 23, 2009

10.2 Blurred vision

Lies all well disguised, masses all hypnotized
Terror's all you hear, war won't make it disappear
Leader's teach us, everything we shouldn't be
everyday people, this is no Democracy!

(a song in support of the Iranian people, try or here)

Saturday, April 4, 2009

10.1 Truth or Consequences

Drug companies in Taiwan probably have sold the most atropine eyedrops than anywhere in the universe. You might wonder what it is used for. It turns out that atropine drops and other cycloplegics are used to control the progression of school myopia.

There has been a long history of cycloplegics used for this purpose; however, it has never gained any popularity elsewhere. In fact, atropine in particular is prescribed, if at all, only for the treatment of amblyopia. As it does appear as efficacious as eye patching; although the treatment is short-term. In contrast, atropine treatment for myopia goes on for years.

Since so many myopic children in Taiwan are treated with cycloplegics and who do not wear optical corrections in school, teachers are running out of front-row seats for these children and start to question this practice.

Do the cycloplegics work? Yes, if one considers less myopia progression a success and a goal by itself. What about the ultimate purpose? Unclear. Because cycloplegics do not reverse myopia, which merely slow down the progression. So, by late teens or early 20s when the myopization process naturally stops, patients are still left with moderate to high myopia. The atropine treatment appears to have based on the assumptions that (1) all myopia cases can become degenerative myopes and that (2) high myopia equals ocular diseases developed later in life such as glaucoma and various retinal integrity issues. And by lowering the degree of myopia, these diseases can be avoided. Unfortunately, so far there is no hard evidence to support this proposal. Perhaps a certain segment of the myopic population can indeed benefit from cycloplegia; again, there is no evidence.

And the downside of long-term atropine treatment? Let's see, cycloplegia causes loss of accommodation and prolonged pupil dilation, allows large amounts of UV into the eye, and potentiates chronic narrow-angle glaucoma. Worse, it is not known how long the treatment can continue without irreversible paralysis of ciliary and iris muscles.

There is something amiss here.

Friday, February 27, 2009

9.15 Looking upward and forward

This is a fish named the barreleye ( from Indonesia. The two dots above the mouth are not the eyes, they actually are the nostrils. Where are the eyes? They are inside the see-through head looking upward. The two green caps are in fact lenses of the eyes. The tubular eyes can point forward as well when the barreleye has to find its way around. Why looking up? To see the silhouette/luminescence of an overhead jellyfish or a small fish, so that it can quickly attack.

Looking upward and forward - sounds like a very short lecture on life.

Monday, January 26, 2009

9.14 Galileo's eyes

(Galileo Galilei [1564-1642], circa 1630)

Well, it is only inevitable in this age of TV CSI shows: Scientists from both UK and Italy are now seeking the Vatican's approval to exhume Galileo's body, so that they can do some DNA analysis to figure out what had ailed Galileo's eyes.

This news has been widely reported, see for example, here and here. The scientists' interest is to explain why Galileo described Saturn as having "lateral ears" rather than rings around the planet. And the theory is that poor eyesight was behind the error.

Galileo's drawings of Saturn are shown on the left:

The one on top was sketched in 1610, and the bottom, 1616.

These "arms" were clarified by Dutch astronomer, Christiaan Huygens, in 1659, as a ring system. He was able to do so because of improved telescope optics. [Note: Huygens also discovered Saturn's moon, Titan, and for this reason, the probe exploring Titan is named after him. And a few years later, Jean-Dominique Cassini discovered 4 other major moons of Saturn: Iapetus, Rhea, Tethys, and Dione.]

So what was wrong with Galileo's eyes and vision? It was actually quite well-documented. According to this site, for example:

"Galileo’s sight began to deteriorate in the middle of 1636 when he was 68 years old, and by the end of June 1637 he had lost the use of his right eye while his left eye was affected by a constant discharge. He described seeing a 'luminous halo' around candle flames. To date there has been little speculation by modern optometrists or physicians about the possible causes of Galileo’s blindness. In July 1636 he wrote to his friend, an Italian lawyer living in France, Elia Diodati, 'I have been in bed for five weeks oppressed with weakness and other infirmities. Added to the (proh dolor!) the sight of my right eye - that eye whose labours (I have no hesitation in saying) have had such glorious results, is lost forever. That of the left, which was and is imperfect, is rendered null by a continual running’. He became totally blind early in December 1637, a few months after using the telescope to discover that the moon wobbles on its axis ('lunar libration') which was quite a remarkable observation to make with only one useful eye. At this point he wrote to Father Castelli noting that 'The noblest eye is darkened which nature ever made, an eye so privileged and so gifted with rare qualities that it may with truth be said to have seen more than the eyes of all those who are gone, and to have opened the eyes of all those who are to come'."

The keywords are shown in red. The symptom/sign suggests active keratitis [discharge] accompanied by corneal edema [halo]. And since both eyes eventually lost vision, it would imply a chronic retinal problem, perhaps posterior uveitis. The left eye was probably further complicated by band keratopathy in his last years. His 20X telescope was actually a low-vision device - at least by 1616, Galilio appeared to still have retained enough vision (at least 20/400) to allow somewhat accurate observation of Saturn's rings/arms.

What the proposed DNA analysis can prove? Probably not much. The project is expected to cost around £282,000, by the way.

Friday, January 23, 2009

Year of Recovery

Happy Lunar New Year

It is a year of 扭(牛)轉乾坤, i.e.,
a year of (bullish) recovery.


Monday, January 5, 2009

9.13 Five-, 6-, 7-, 8-pointed stars

How many points does a star emanate?

It depends on where you are from.

In the US, five (5). You see 5-pointed stars on a certain sidewalk in Hollywood (e.g., left). Even the Texaco logo has such a star. It is also the basic standard emblem of the US Military. The American flag has 50 such stars. And the national flags of Singapore, New Zealand, Pakistan, Turkey, China, Somalia, and many others all have the 5-pointed star(s) as part of the design.

There are of course the 6-pointed stars, e.g., the Marian star and the star of David.

The municipal flag of Chicago has four 6-pointed stars (right), each commemorating a specific event and each of the 6 points, a special meaning. A fifth star has been proposed on more than one occasion, but none has been realized thus far. Further, the white stripes = north, west and south sides of Chicago, and the two blue stripes = Lake Michigan and Chicago River, respectively.

Interestingly, the 6-pointed star is also a sacred Mongol symbol, seen, e.g., on the entry to Humayun's tomb in New Delhi (below):

Seven-pointed stars? Of course, the Australian flag has 5 of them:

It often puzzles the tourists: 6 states + 2 territories = 7, not 8 points? (Dared to be different, these Aussies?)

Actually, it is a bit more complicated than the simple math. The winner of the original flag design (contest conducted in 1901) had 5, 6, 7 and 8 points (below, left).

King Edward VII approved the current 5- and 7-pointed star version.

There have been many iterations on the significance of these designs which we'll leave to the real historians to contemplate.

The only national flag that has an 8-pointed star seems to be that of Azerbaijan (below). This star is supposed to be the symbol of Rub El Hizb (Arabic: رب الحزب‎). And the design here was modified in 1991:
Seriously, how many points of a real heavenly star are we supposed to see? Let's see:

In the human eye, the crystalline lens is composed of a single-cell-layer epithelium in the front and a cortex that envelopes the nucleus. The epithelial cells elongate into cortical fiber cells and the ends are jointed at the front and the back, known as the sutures. The front suture is shaped as an upright Y and the posterior, an inverted Y. Superimposing the two Ys, what do you get? Yes, 6-points. This is the basic pattern. Often there are branches off the basic Ys. In other words, stars (in effect, point sources of light) should appear 6-pointed (with/without branches) to most of us. If you see 5 or 7 points, have your eyes examined.

Occasionally, something goes wrong with the sutures, then you'd end up with sutural cataracts. A real bad case is shown here:
See the huge Y within the dilated pupil? Most sutural cataracts are, however, less dramatic than the one shown here. Most have no significant impact on vision except the 6-pointed stars look even more prominent.