Snap Shots: ‘Non-contagious’ Red Eye

by Harry Flashman

There are many causes for ‘red eye’. Ignoring the obvious ones of late nights with excessive alcohol intake and scratchy contact lenses or the highly contagious medical ‘red eye’, photographic ‘red eye’ is a condition often seen with many flash photographs these days. The photographic cause of ‘red eye’ is the flash burst illuminating the back of the eyeball! This is also particularly a problem with most cameras that have their own in-built flash. And that’s about most of them these days.

The reason for this is that the beam of light from the flash is very close to and parallel with the optical axis of the lens, so the lens “looks” directly into the back surface of the eyeball illuminated by the flash beam. Another reason for the prevalence of ‘red eye’ is that in low light situations (and that’s the times when you have to use flash illumination) the subject’s pupils are dilated and it becomes even easier to see into the eye.

Now the observant ones amongst you will have noted that you don’t get ‘red eye’ when you photograph the family dog! You get ‘white eye’ or ‘green eye’. You see, the red color comes from light that reflects off the blood vessels in the retina of our eyes. However, in many animals, including dogs, cats and deer, the retina has a special reflective layer called the Tapetum Lucidum that acts almost like a mirror at the back of their eyes. If you shine a flashlight or headlights into their eyes at night, their eyes shine back at you with bright, white light. The flash burst is reflected in the same way.

The way to get around the problem is actually quite difficult. Pro shooters will use a flash gun mounted to the side of the camera, so the flash burst actually goes across the eyeball at an angle and does not light up the back of the eyeball, where the camera lens is “looking” at. I use an ancient Metz 45 CT1, mainly just for that reason.

However, not everyone wants a large flash gun hanging off their camera, so the camera manufacturers have produced a ‘pre-flash’ mode (sometimes called ‘red eye’ mode).

The clever camera manufacturers have now begun incorporating a “pre-flash” mode before the main flash fires to make the pupil contract, so it is less likely that you will see inside the eyeball. The only problem here is that many people imagine that the “pre-flash” going off means picture taking is over and move away just as the main flash fires. Best to warn the subject that there will be two flashes, with the real one being the last one! So many good shots have been ruined by the subject walking off before the shutter had fired, thinking that the pre-flash was the right one!

Another trick is to turn on all the room lights, if you are photographing indoors. If the ambient light levels are quite high, this again causes the pupil to constrict. It is the dilated pupil that lets just so much light into the back of the eye, which also explains why photographs of people at parties have even more ‘red eye’. (Alcohol dilates the pupil!)

Of course, if you still end up with ‘red eye’, there are other ways of now correcting the situation. All these involve the use of digitizing the image (scanning or using a digital camera) and then using an image manipulating programme.

One of the simplest is to use Paint Brush, put it on a nice green, lower the opacity, and paint over the red using your zoom tool. Green, for these purposes, is opposite red on the colour wheel, so it’s the complementary colour, and they will cancel each other out. This method will work for any version. You will just have to vary the opacity, depending on how red the eye is. The other digital method is to use Paint Shop Pro version 7 which has Choose Effects, Enhance Photo, and then click on Red-eye Removal.

by Dr. Iain Corness, Consultant

I was reliably informed that there were five patients admitted recently to my local hospital, all suffering from Dengue fever. The last wave of this recurrent epidemic was just over six months ago, so my warning is worth repeating.

Perusal of the news all over Thailand shows that Dengue fever is again on the up and up. In fact, in the North, the incidence of Dengue Haemorrhagic Fever has tripled compared to last year. Even on our tourist islands this has become a problem, and on some of the surrounding islands as well. With the water that will be wasted over Songkran, this will just exacerbate the situation.

However, first you should understand a little more about Dengue. This is a nasty viral condition that has been coming round in epidemic waves for many years. It is also a fairly wide spread virus with 2.5 billion people living in Dengue endemic areas. We, in Thailand, belong to that group.

Like Malaria, the virus is carried by mosquitoes, this time by one called Aedes aegypti. The virus itself is related to Japanese encephalitis, Murray Valley encephalitis and yellow fever, and there are four “serotypes” or subgroups of it.

The mosquito lays its eggs in water containers, preferring the clean water found in water tanks and pots, in the saucers under pot plants and even under the pet’s food dish. Inside discarded car tyres are another favourite spot. These mosquitoes are not of the adventurous type and feed during the day and spend their time within 200 metres of their hatchery. Consequently, the eradication of any local breeding areas becomes very important towards maintaining your own health, as you can see. Keep your home free from lying water for a radius of 200 metres and you’re looking good!

Simple Dengue (if you can call it that) has an incubation period of around 4 to 7 days and then the full blown symptoms of high fever and headache begin. The headache is usually behind the eyes and is made worse by eye movement. From there the pains progress to the limbs with acute muscle pains, which gave it the old name “Break Bone Fever”. Interestingly, some patients complain of a metallic taste in the mouth. (Please don’t ask - I have no idea why!)

With our ability to treat the viral ailments being very limited, the defence against the Dengue virus lies in Health and Hygiene initiatives, if you get mosquitoes in the house during the day. For example, do you regularly change the water in containers the Aedes aegypti mosquito might call home? Do you have mosquito screens? Does baby sleep under a mosquito net? If the answer to these questions is “no”, then perhaps it is time to look critically at your own Dengue prevention plan. Let me assure you, it is not a disease you want! And the Haemorrhagic form in particular.

The other precautions are to wear long trousers and long sleeved shirts, especially at sun up and sun down, when the mosquito is at its most ravenous. The other factor to remember is “D” for Dengue and “D” for DEET. DEET is the magic ingredient in mosquito repellents, so when you go to buy some, check the label - if it has DEET, then get it. And then remember to use it!

So to avoid falling prey to Aedes aegypti, empty free standing water around the home, use screens and mosquito nets if necessary and apply repellent containing DEET. Best of luck!

Part Two: Shot Down and Rescued (continued...)

by Duncan steam

To recap last week, a group of Allied airmen, British and American, were shot down by the Japanese over Thailand on the morning of 29 May 1945. Survivors escaped into the jungle, but within 15 minutes, sympathetic Thais took the downed airmen and hid them in their small village.

The following morning, the airmen “were startled by a commotion outside. On glancing through the bamboo screens around us we spotted what looked like a Military Patrol on horseback approaching the village ... What really scared us for awhile was the leader who looked so much like a Japanese officer.”

The troops were in fact Thai military police that had been dispatched from Bangkok to find the airmen and take them back to the capital. They were told that they were to move immediately from the village and, “Hidden near the bank of a river until nightfall. The reason for this move was that a Japanese army patrol was already searching for us. We later learned that the Japs were ambushed by the police and villagers and all were killed and buried.”

The Allied airmen were taken on a night ride by bullock cart and then transferred to a sampan to traverse a river before eventually arriving at the home of the police captain in charge of Nakhon Sawan a couple of days later.

Nervous, tired and hungry they, “Were given a really good welcome by the police captain’s family [who] gave us a good meal...” Despite their precarious position they slept soundly, especially Smith, Pugh, Woods, Roe, Parsons and Copley as they had only completed their longest mission the day before. That flight had been to, “Singapore where four Australians were disrupting the Japanese from a hideout in the mountains. The mission covered 3000 miles and took 23 hours and 50 minutes.”

The next step of their journey to Bangkok was also fraught with the possibility of discovery by the Japanese. The group was moved from the house, across an open field to the edge of the railway line where Japanese troops stood guard at a rail bridge just 100 metres away. Managing to escape detection, they went aboard a Thai police motor launch. “The boat we were loaded aboard was about 25 ft. in length with a beam of only about 3 ft. I believe it had a wooden and metal covering over the so-called deck with the usual type of bamboo roll-up side screens. The screens were kept down most of the time to keep us hidden from passing craft - sometimes Japanese patrols - as the river we were on was one of the main waterways to Bangkok.”