Chlamydia and Blindness
Some time ago, we wrote about the devastating effects of the spread of chlamydia among the vulnerable koala bears of Australia. Since then, Australian scientists have been getting closer to the development of a vaccination for these beautiful marsupials against, what is for them, an extremely dangerous disease, sometimes rendering those infected, blind. Based on the results of a small but successful trial in Brisbane, things might be looking up for the koala bear and maybe even humans alike.
Chlamydia is still one of the most common sexually transmitted infections around today yet rates are generally consistent year after year. Apart from spreading awareness and launching STI health campaigns, there is little else we can do without a vaccine. Part of the problem is that in over 80% of cases, the infection is asymptomatic, and those who carry it spread the infection without even knowing. In koalas, the untreated infection can lead to blindness and infertility. Chlamydia also causes infertility in humans if left untreated. Other complications include pelvic inflammatory disease (PID), which causes infertility, ectopic pregnancy and miscarriage.
In this promising study, 30 out of 60 koalas were vaccinated and the trial group was then observed in its natural surroundings via radio collars thereafter. It was discovered that 7/8 koalas who were suffering from an eye infection at the time of vaccination, showed improvements. In stark contrast, of the koalas who were not vaccinated, 4/6 who were suffering from eye infections, only got worse. Symptoms of the infection in koalas manifest themselves in eye infections but also as infections of the reproductive tract.
Those who were infected with the strain of chlamydia, and who were simultaneously vaccinated, did not go on to experience the full-blown infection. This is a really positive outcome considering the loss of life among this species due, not only to the spread of the chlamydia infection which, in some areas, infection rates are up at 90%, but also down to habitat loss.
Koalas and humans both respond well to antibiotic treatment but in the case of koalas, it is not feasible to treat every koala infected and maintain control over the spread. The vaccine could act as a model for a human vaccine though, a development that has been researched for decades now, but so far, to no avail. If we could use the koala vaccine as a model for the human vaccine, we could prevent the infection across a large portion of the population. The result of this study is good news for the koalas, but it inspires hope for us too.
In the meantime, partner notification, diagnoses, and successful treatments (re-testing), are the key to beating chlamydia and stymieing the spread. Telling partners will directly affect rates of diagnosis, rates that must be consistently maintained in order to gain better control over the spread of infection. You can find your local testing clinic here. If your are reluctant to attend a clinic then there are online options such as this website.
You can read more about Chlamydia and blindness here.
Research developments may lead to new amblyopia treatments
A recent study has found out new information about the brain and the way that the organ communicates with the eyes. This research, published in the journal Nature, could lead to a better understanding of the plasticity of the brain and new treatments for the condition called amblyopia (commonly known as ‘lazy eye’).
While the brain develops, the visual system starts a process called ocular dominance. It is a normal process that aids the development of the eyes and the visual system. It allows the two eyes to compete for the middle ground, called binocular zone. However, if one of the eyes cannot effectively compete with the other, then this process causes an imbalance of vision. This process has been compared and fit into the plasticity model, which is the model that explains how the eyes can adapt differently to different external stimuli. According to plasticity in fact, the brain can develop new stronger connections if enough cells in the organ fire at the right times. However, this model also says that a specific amount of cells have to be firing in order for the brain to be able to change its behaviour and build stronger connections with the eyes.
Hence, this research was looking at how to explain ocular dominance plasticity. It has been found that when a mouse’s eye is patched, the firing of the cells gets reduced by about half just as expected. However the researchers discovered, by measuring the cells activity in the 24 hours afterwards, that the firing rate increased again.
They found that this increase that brought back the firing to the normal range was due to a brain circuit that usually has been found to inhibit the cell’s firing. Hence, this brain circuit could be the answer to finding new treatments to the ‘lazy eye’ condition. Medications could be developed to help ‘turn on’ this circuit. This might lead to visual improvements for older patients.
For more information and to purchase the access to the complete study, please visit the article page in the website of the journal Nature.
Does sex really affect your eyesight?
Viagra is used in the treatment of men with erectile dysfunction. Viagra blocks the enzyme known as phosphodiesterase-5 (PDE-5), which leads to smooth muscle relaxation and an increase in blood flow to the penis, and thus to an erection.
Clinical trials have shown that Viagra is well tolerated but, like all medicines, it may cause side effects. One effect that has attracted particular attention is visual disturbance, sometimes referred to as ‘blue vision’. It happens more frequently when high doses of Viagra are taken or in cases of drug abuse. It may occur because Viagra also blocks PDE-6 (although to a much lesser degree than PDE-5), which is involved in converting light into electrical signals in the light-sensitive cells of the eye.
Changes in blue/green colour discrimination were found in some men given single Viagra doses of 100 mg (the maximum recommended dose). Effects were mild and temporary, seen at one hour after dosing and disappearing after two hours. Viagra did not affect visual acuity (clearness) or contrast sensitivity in this study. Another study demonstrated that Viagra had no clinically relevant effects on the vision of patients with early age-related macular degeneration (an eye disorder resulting in loss of central vision).
In clinical trials where Viagra was taken when needed and at the recommended dose, 3% of men reported abnormal vision, which was mainly colour tinge to vision, increased sensitivity to light or blurred vision. The number of events increased with dose and with doses above the recommended dose range.
Men should be advised to stop taking Viagra and notify a doctor if they experience visual defects. They should also avoid driving as it may reduce their concentration. These side effects are usually mild to moderate in severity and temporary, disappearing as the effects of the drug wear off.
Rarely, in post-marketing studies, non-arteritic anterior ischemic optic neuropathy or NAION that causes reduced vision has also been associated with use of PDE5 inhibitors, including Viagra. However, it is not certain that these medicines caused NAION as these men also had other risk factors (such as diabetes, coronary artery disease, and high blood pressure) for this condition. As a precaution, Viagra is not recommended for men who have NAION and loss of vision in one eye. It is also not advised for use by men with a genetic degenerative condition of the retina (such as retinitis pigmentosa) because the effects of the drug in these people are unknown.
So where does this leave us? None of this indicates that taking Viagra is likely to seriously affect eye sight. However, as with all medications, it does indicate that it is preferable to seek advice before taking Viagra and to take the dose recommended by your doctor. It would appear that doctors are agreed that there is no risk here and some of the claims being made against Pfizer are opportunistic to say the least.
Dry Eye Syndrome
It is easy for people to experience dry eyes these days.
Dry eyes can be caused by high heat, wearing contact lenses for too long, dust and wind and aging. It could also be a symptom of other more serious problems.
In any case, the common experience is feeling the eye irritated, redness in the eye and the feeling of a foreign object in the eye.
Dry eye is ultimately due to the eye not being able to produce enough moisture due to one of the aforementioned problems. Staring at a computer screen can also affect the eye in this way, because people tend to blink less when looking at a screen. If you combine multiple common causes that everybody can be easily exposed to (heat, contact lens wearing, and computer) then you might understand why you eye has been feeling very dry for the past few days.
What to do
- Drink plenty of water: water can help producing more moisture in the eye.
- Avoid wearing contact lenses: if possible, switch back to your glasses for a few days.
- Limit staring at the computer: this is a hard one if you work in an office. However, try to take small eye breaks (i.e. look at something else for a little while every 10 to 15 minutes), or consciously try make the effort to blink more when looking at the screen. You might also want to consider changing the settings in your computer so that your screen is not too bright, and adjusting the screen to a father distance.
- Buy Artificial Tears: they might help moisture the eye more quickly. For best results, apply them without having your contact lenses on.
- Get omega-3 fatty acids: you can take them as a supplement or you can have meals based on salmon or sardines. These acids help reduce the risk of dry eyes
If you think your dry eyes are due to the hot environment:
Other ways to reduce dry eyes are to buy a set of sunglasses that might help get rid of the problem as they help lock moisture in, especially if you know your dry eyes are due to the environment. Another option is to buy a humidifier and/or an air cleaner.
Obviously, if you think you got dry eyes after wearing contact lenses, you might want to consider switching to another brand. In the same way, if you are taking medication that you think has affected your eye in this way, talk to your doctor as you might want to discontinue it.
More information on dry eyes can be found on this page: http://www.allaboutvision.com/conditions/dryeye.htm
In any case, if you are worried, your lifestyle is getting affected by the condition or if you think you’ve had dry eyes for a long time, talk to your optometrist.
Oculolinctus
Recently a few newspapers in the UK started talking about the new Japanese fetish called “oculolinctus”. It is also called ‘worming’ informally.
Basically, it consists of licking other people’s eyeballs for sexual purpose. As the eye is full of nerve endings, it is supposed to turn people on and bring them pleasure. Inasmuch as the eye is indeed full of nerve endings, we really discourage anyone from trying this, as the receiver of this ‘practice’ can really get his/her eye damaged!
The eye is a very sensitive organ, and it is easy to imbalance its natural state and chemistry. For example, wearing heavy cheap eye make-up all the time, not drinking enough or staring too much at a computer or TV screen are all things that should be avoided when trying to take care of your eyes.
This is why apparently Japanese teenagers and young adults practising this new “sexual activity” have to wear eye patches afterwards.
Be aware that the eye gets swollen, red and you can also catch infections such as chlamydia if you try this. In the worst cases, you might even end up blind. Please don’t try this.
Bacteria and Eye infections: good news
The Journal PLoS One has published a recent study on how good bacteria can counter-act and fight bad bacteria, found in the eye, that are becoming more resistant to antibiotics, infect the eye and can lead to blindness.
The bad bacteria in question are Serratia marcescens and Pseudomonas aeruginosa. The good bacteria are Micavibrio aeruginosavorus and Bdellovibrio baceriovorus.
Here’s how they tested both in a three-part experiment.
The first part of the research was conducted to see whether the first two (the bad bacteria) actually die because of the last two (the good bacteria).
The second a third experiments were done to see whether the ‘good’ bacteria are actually not harmful to the eye. The second tested the bacteria on the cells that are present in the human eye. The results were that the bacteria did not inflame or irritate the eye cells at all.
In the third experiment, they tested again the bacteria against worms. While the worms died quickly after the injection of the bad bacteria, they had an 11-day survival rate (survival between 93.3 and 100%) after the injection of the good bacteria, suggesting that the bacteria was not harmful to their existence.
After these preliminary tests that exhibited very positive results, we await new tests and research on humans, as it seems that the good bacteria, or predator bacteria, can live in the eye without causing any damage to it and can help eliminate the bad bacteria, or the pathogenic bacteria.
For more information on this research, please visit: http://www.sciencedaily.com/releases/2013/06/130620191955.htm
Strabismus
What is strabismus?
Strabismus (often called crossed eyes or squint) is a disorder that affects the eye muscles, causing the eyes to look in different directions and on different things at any one time. Either one or both eyes may look inwards, outwards, upwards or downwards. This misalignment may occur all or some of the time, and may affect the same eye always or alternate between the eyes.
How common is strabismus?
Strabismus is estimated to occur in up to 5% of children, although adults can also develop the problem.
What does strabismus do to eyesight?
Early in the disorder, people with strabismus experience double vision and confusion because the eyes are not focusing on the same thing. Eventually, the view from the ‘turned’ eye will be ignored (suppressed) by the brain as it tries to prevent seeing double. The view of the world is not three-dimensional; it lacks depth and distance. Left untreated, constant eye turning can result in reduced vision in the eye (or Amblyopia, also known as lazy eye).
What causes strabismus?
While strabismus tends to occur in children at a young age, it may also develop in older children and in adults. Complications and injuries to the eye muscle are causes of strabismus. However, strabismus frequently arises from defects in nerves that send signals to the eye muscles or in the part of the brain that controls eye movements. Strabismus is a heritable condition and therefore can run in families. It can occur in people with other disorders, such as Down syndrome and cerebral palsy, or who have had a stroke or head trauma. Strabismus may also arise in people who continually try to correct their far-sighted vision.
Testing for strabismus
Normally, it is advised that all children have their eyes examined at about nine months of age. However, regardless of age, advice should be sought for any notable eye problem.
A complete medical history of the patient is taken, including family history of eye problems and the patient’s general health, other diagnoses and medicines. Essential to the diagnosis, is a detailed history of the eye problem, such as when it began and the nature of the eye turning. For a confirmed diagnosis of strabismus, the eyes are given a thorough examination. This includes observing the eye parts, and tests for visual acuity, alignment, focusing, and refraction (lens strength).
How is strabismus treated?
Treatment of strabismus is necessary as it will not disappear with age and may worsen. Treatment aims to improve the alignment of the eye and enable the eyes to move in a coordinated fashion. It will depend on the characteristics of the condition.
Prescription eye glasses may be used to get rid of eye turn and other problems with vision, such as farsightedness. An eye patch can be worn over the ‘good’ eye to encourage the ‘lazy’ one to function properly. Prism lenses, which change the course of light entering the eye and reduce the extent of eye movement required for the eye to focus, can sometimes correct the problem. Lenses may be all that is needed when the condition is mild but, more often, vision therapy and/or surgery are also required.
Vision therapy aims to improve movement, coordination and focusing of the eyes. The series of eye exercises re-establishes normal vision by educating the eyes and the brain to function together, the eyes to move together, and the brain to effectively merge the images from both eyes into one. Vision therapy is very effective and the improvement is long-lasting.
Surgery performed on the eye muscles aims to align the eyes and make the turned eye appear straight. It involves altering the length or moving the eye muscles. Surgery improves the cosmetic appearance of the eye but may not correct vision, particularly if the problem is not with the eye muscles only. This means that vision therapy may also be recommended to coordinate eye and brain functioning.
‘Lazy Eye’ treated playing Tetris?
This week we want to discuss a recent study that suggests that amblyopia, commonly known as ‘lazy eye’, can be treated by playing tetris.
First, though, it is best to discuss and talk about what the condition actually is.
What is Amblyopia?
Amblyopia is a lower-to-standard acquisition of images through vision. It can happen because the optic nerve is not transmitting the visual messages properly, or when the brain stops acquiring the image from one eye.
Why would the brain do that?
The brain can stop getting an image from one of the eyes because of different reasons. For instance, it could be due to strabismus. In this case, it happens when the brain perceives the images from the two eyes to be different (i.e. it understands that double-vision is occurring).
How can Amblyopia be treated?
Amblyopia is not an intrinsic neurological problem. Rather, it is an acquired bad habit. In patients with amblyopia there is nothing wrong with the eye itself. Hence, because it is a problem of developmental nature, the brain can be re-taught to “see” from the weaker eye.
Since now, most of the treatments were thought to be effective only in children. The main treatment was to occlude the strongest eye, either with an eye-patch or by applying drops of atropine. This would force the brain to acquire the image from the weakest eye, and would strengthen the communication between the two.
What is this new research showing?
The aforementioned treatment applications have not been successful with the majority of adults. This recent academic report, however, has found a new approach that can help adults with amblyopia. This report was published in the journal Current Biology and conducted by Li et al. The researchers have found that the brain still maintains a level of plasticity in adulthood. However, it has not been tackled in the right way. This research suggests that covering the strongest eye might be detrimental, indeed, to curing amblyopia. What these researchers did was to force the eyes to work together.
Why tetris?
Here’s where tetris comes along: one eye was forced to see the blocks falling and the other eye was only allowed to see the ground where they would fall. After two weeks, patients had already improved vision. Further studies are needed to confirm whether covering the strongest eye might indeed not be the best treatment to cure amblyopia. In any case, this remains an interesting research. The journal article of this research can be found here.