Protect Health

Lasik Eye Surgery Complications

Food - 1 year ago - Admin

What are some of the possible complications of Lasik eye surgery?

Undercorrection this occurs when the expected vision correction falls short of the desired outcome. This occurs more commonly with patients who have a high degree of nearsightedness (only objects close up are clear), farsightedness (only objects far away are clear) or astigmatism (images both far and near are distorted). Why? There is more laser corneal sculpting that needs to occur with patients having higher degrees of vision imperfection. When choosing your Lasik eye surgeon, its important to ask them what percentage of their patients need retreatment for undercorrection. This should be something that they are willing to freely discuss with you. If not, walk away! This is not to be confused with a planned slight undercorrection for nearsighted patients over forty years old which aids their reading vision. But this is something that you and your Lasik eye surgeon would have discussed before your surgery.

Overcorrection this complication occurs less frequently than undercorrection and results when the amount of correction (corneal laser sculpting) exceeds what is planned. Slight overcorrection can be temporary and may resolve itself in the first month following Lasik eye surgery. Patients can manage slight overcorrections by wearing glasses until their vision resolves. Some patients with overcorrection may need additional Lasik eye surgery 3 to 6 months following their first surgery.

Dry Eye many Lasik eye surgery patients may experience the feeling of grittiness in their eyes following surgery. This condition usually resolves itself in 3 to 6 months and may be helped by using lubricating eye drops. Patients using birth control pills and patients going through menopause may experience this condition more often. If dry eye continues beyond 6 months, your Lasik eye surgeon may recommend blocking your tear ducts with tiny silicon plugs to prevent tears from draining away too quickly.

Corneal abrasion a small percentage of Lasik eye surgery patients may develop a small corneal abrasion (scrape) caused by the microkeratome (instrument used to create corneal flap) used during surgery. This abrasion is generally not serious and will heal quickly. Your Lasik eye surgeon may temporarily place a thin bandage contact lens on your eye to promote healing. While your abrasion is healing, your vision will be blurry.

Night glare this annoying condition may not affect your vision clarity but patients may see halos or ghosting of images at night during the first month following surgery. Night glare generally improves in 3 months and often disappears within 6 months. Patients with large pupils and more severe vision impairment may be more prone to night glare.

Corneal flap complication this occurs when the corneal flap is too small, too thin or is an irregular shape. In some cases the corneal flap may shift slightly following surgery if a patient rubs their eyes during the first 6 hours after surgery. If the flap does shift, wrinkles can form causing distorted vision. A second procedure may be necessary to smooth out the wrinkles and improve vision.

Infection although this is the most feared complication of Lasik eye surgery patients, it is extremely rare. If your eye is going to become infected, chances are it will happen in the first 72 hours following surgery and will be treated with antibiotic eye drops. For this reason it is very important to avoid eye makeup, hot tubs and swimming pools for at least the first week following Lasik eye surgery.

The risks of Lasik eye surgery are low with an experienced Lasik eye surgeon but you need to be aware of possible complications prior to surgery. Your Lasik eye surgeon should freely discuss all possible complications of Lasik eye surgery prior to surgery. Do everything you can to put your eyes in the best possible hands.

Eyewitness Testimony: An Enduring Topic Of Psychological Enquiry

Food - 1 year ago - Admin

The study of eyewitness testimony can be traced back over 100 years. This article outlines how it all began and examines the most commonly researched areas of investigation.

In 1896 Albert Von Schrenk-Notzing testified at the trial of a man accused of murdering three women. Drawing on research into memory and suggestibility he argued that pre-trial publicity meant that witnesses could not distinguish between what they actually saw and what had been reported in the press.

The formal study of eyewitness testimony is usually examined within a framework of cognitive processing, which put simply refers to the different ways in which we make sense of the world around us.

We do this by employing the mental skills at our disposal such as thinking, perception, memory, awareness, reasoning and judgment. Although cognitive processes can only be inferred and cannot be seen directly, they all have very important practical implications within a legal context.

Given that the way we think, perceive, reason and judge can be less than perfect its easy to understand why the factors influencing these processes are studied by psychologists’; not least because of the grave implications that this imperfection can have within the criminal justice system. As Huff and Rattner note:

the single most important factor contributing to wrongful conviction is eyewitness misidentification.

Stages of eyewitness memory:

Stage 1: Witnessing the incident.

When witnessing an incident, information about the event is entered into memory, however, research has shown that the accuracy of this initial information acquisition can be influenced by a number of factors.

Take the duration of the event being witnessed for instance. In a very simple experiment conducted by Clifford and Richards(1977), participants are instructed to approach a number of police officers and engage in conversation for either 15 or 30 seconds.

Thirty seconds after the conversation ends, the experimenter asks the police officer to recall details of the person they had just been speaking to using a 10-item checklist. The checklist contains items relating to the persons appearance such as hair colour, facial hair etc. The results of the study showed that in the longer 30 second condition, police were significantly more accurate in their recall.

Stage 2: Waiting period before giving evidence.

This stage is concerned with the period of retention between perception i.e., seeing an incident and the subsequent recollection of that incident. Unsurprisingly, research has consistently found that the longer the gap between witnessing an incident and recalling the incident, the less accurate the recollection of that incident becomes.

There have been numerous experiments, usually related to a staged event, that support this contention. Malpass and Devine (1981), for instance, compared the accuracy of witness identifications after 3 days (short retention period) and 5 months (long retention period). The study found no false identifications after 3 days but after 5 months, 35% of identifications were false.

Stage 3: Giving evidence.

The final stage in the eyewitness memory process relates to the ability of the witness to access and retrieve information from memory. In a legal context, the retrieval of information is usually elicited through a process of questioning and it is for this reason that a great deal of research has investigated the impact of types of questioning on eyewitness memory.

The most substantial body of research has concerned leading questions, which has consistently shown that even very subtle changes in the wording of a question can influence subsequent testimony.

One of the most notable researchers in this field is Elizabeth Loftus who has been investigating eyewitness testimony for over thirty years. In one of her classic studies, participants witnessed a film of a car accident and were asked to estimate the speed of the cars involved. One group of witnesses were asked to estimate the speed of the cars when they contacted each other. A second group of witnesses were asked to estimate the speed of the cars when they smashed each other.

On average the first ‘contacted’ group gave an estimate of 31.8 miles per hour. Whereas, the average speed in the ‘second’ smashed group was 40.8 miles per hour.

Experimental validity:

In any discussion of eyewitness memory, you’ll see the terms, ‘experiment’, ‘participants’ and ‘staged event’ frequently used. This is because the majority of research into eyewitness memory has been conducted within psychology laboratories.

This raises the very important issue of whether it is possible to generalise the findings obtained under these artificial conditions to real life cases.

The simple, if unsatisfactory answer is that it is very difficult to say. Take for instance the work of Yuille and Cutshall, these researchers conducted a case study with witnesses to a real shooting incident, interviewing them just after the event and again 5 months later. They concluded that the performance and accuracy of the witnesses differed in several respects to what would be expected according to the experimental literature.

However, the strength of laboratory based research is that the experimenter is able to exercise a great deal of control over what happens. In the case study reported by Yuille and Cutshall, it was impossible to know the extent to which the witnesses had conferred and how much media coverage of the incident they had seen, and how much influence this had on their testimony.

If you’d like to find out more about eyewitness memory, you can do so by visiting www.all-about-forensic-psychology.com