Difference between MEL 80 (WaveFront) & VISX S4 (CustomVue)

For a newbie, how would I know what the difference between MEL 80 and VISX S4 is? I believe writing this blog is also a way of answering my own inquiries and I hope in some way, I would be able to help someone who is having difficulty making decisions about laser eye surgery.  Though it is not just a laser machine that matters when making decision, it is actually self-assuring to be able to understand the background work before going through the surgery.

Well, MEL 80 Excimer Laser System was established by Carl Zeiss Meditec, Germany and it is an excimer laser designed for LASIK (Laser-Assisted in Site Keratomileusis) to reduce or eliminate nearsightedness and astigmatism. The system is designed for patients with a near-sightedness of less than or equal to -7.0 D with or without refractive astigmatism of less than or equal to -3.0 D and patients who are over 21 years old with stable eyesight. After numerous clinical trials, it was found that 93% of patients were corrected at three months to 20/20, 41% were corrected to 20/12.5 or better at six months and it was finally approved by USFDA in Apr 2006.

Next, VISX Star S4 IR Excimer laser system was developed by AMO, USA and received FDA approval in 2007. It is designed for wavefront-guided LASIK treatment and it treats nearsightedness by removing tissue from the centre of cornea to flatten it and astigmatism by flattening the central cornea by different amounts and at different orientations to correct for uneven focus. It has also been through numerous clinical trials (more than 3 million) with IntraLase system and it is considered the most internationally-recognized laser system.

MEL-80 is known for its short ablation time as this means procedure time is reduced for greater patient comfort and with its small 0.7mm spot, it allows the finest corrections while maintaining the benefits of smooth ablation. With its shortened stroma exposure time, this also means faster visual recovery for the patients and it also has an active eyetracker with excellent feedback times with an ultra-rapid IR camera to catch the exact positions of both pupil and limbus during the laser treatment.

As for VISX S4, it uses invisible UV light pulses to remove precise amount of corneal tissue, an active 3D eye-tracker to detect the eye position and align the laser pulse with the cornea, a diagnostic wavefront sensor for the automated measurement, analysis and recording of refractive errors and lastly, it has an automated Iris Registration (IR) system to rotate and align the treatment while compensating for eye cyclo-rotation and physiologic pupil migration. On top of that, its Variable Spot Scanning (VSS) delivers variable beam sizes from as small as 0.65mm to 6.5mm over the treatment area which conserves tissue, optimizes treatment times, reduces corneal drying and adverse thermal load to the delicate corneal tissue. Together with Variable Repetition Rate (VRR), the laser’s repetition rate varies from 6 to 20 Hz and by changing the size and placement of laser beam continuously, VISX is able to deliver the required ablation pattern rapidly and precisely.

So after all the information, which one should I choose for my vision correction surgery? Actually depending on the seriousness of your eyesight, the ophthalmologist will decide which is suitable for your eyes.  So how does the surgeon know which is suitable for you? The first thing after stepping into the eye clinic and going through the registration is that, the eye specialist will do a thorough eye examination test including vision test, intraocular pressure, pupil size, ORB scan, pachy and endothelium cell test, which will take about 1 hour.  Next, with this information the consultant will explain to you the available laser surgery (LASEK/LASIK) methods in the clinic, differences and which one is suitable for your eyes. A good consultant will lay out the price list for the surgeries that you could go through instead of picking out the most expensive one for you. With your budget, you could decide the one that is the best for you.

With this information in mind before making the decision, you will have a chance to meet the surgeon and the surgeon will explain the suitable method to you and answer your inquiries. The surgeon will also examine your eyes again to check whether there are any abnormalities in your eyes. After that you will have another meeting with your consultant to decide whether you will have the surgery or you will call again to confirm.  Before the actual surgery, there should be another eye examination to ensure the eye power is stable. 

At present, there are many eye clinics offering laser surgeries at very low prices but I think for the sake of the eyes, it is not advisable to choose the cheapest one without being given sufficient information. Sometimes consultants do not provide all the facts about the patient’s eye condition because firstly, the clinic only has one laser system and secondly, they don’t want to lose their customers even though they could not correct your eyes using their system. Serious side-effects and permanent damage could occur if serious consideration is not taken. So with all these in mind, check out my next article on LASEK and iLASIK in 2 weeks time        

The Market for Spectacle Freedom

In spite of imperfect presbyopia solutions and a depressed economy, the demand for spectacle-free options among the presbyopic is steadily growing. According to an American research company, Market Scope, the penetration of prebyopia-correcting IOLs increased in the fourth quarter of 2009 to about 7% of all cataract procedures in the U.S., said Giulia Newton, vice president of global marketing. She also mentioned that with about 3.2 million cataract procedures performed yearly, which come to about 224,000 cataract procedures using premium IOLs, this penetration has stayed steadily between 6-7% for about 1 year.  On top of that, BSM Consulting Group has also researched those presbyopic patients who opt for premium IOLs had to pay an additional $800 to $900 for multifocal lenses as these are not covered by Medicare. 

In 2010, Professor Howard Fine, who received the Binkhorst Award from American Society of Cataract & Refractive Surgeons, said that even though there are many surgeons doing presbyopic surgeries but IOLs (ReSTOR, ReZOOM) used for correcting both cataract & presbyopia are not in demand yet as patients do not mind using reading glasses or they just want to undergo cataract surgeries. In order to satisfy these patients, IOL manufacturers will continue to work on producing new multifocal and accommodating lenses in order to develop the best technology for cataract-presbyopic patients.    

The latest IOLs developed in England is Rayner Sulcoflex multifocal IOL, which can be implanted in the patients’ sulcus who are pseudophakic with monofocal IOLs.  Another type is Synchrony Dual Optic Accommodating IOL (AMO), which is the first 3D, single-piece, foldable & accommodating IOL with twi separate optics connected by a spring system, that replicates the natural lens by increasing its power when viewing near objects and reducing it when looking at distant objects, allowing the patients to utilize their natural muscle-driven mechanism to move the IOL and achieve spectacle unaided vision.

Besides that, Dr. Fine also mentioned that corneal inlays look like they have some utility and advantages as these inlays are reversible but yet again, the ability to reverse is an imperfect device.  Nevertheless, research has shown that many people in their mid-forties come to the clinics thinking that they have hyperopia, but actually they have slight presbyopia or early signs of cataract. In these cases surgeons will usually recommend an intraocular procedure instead of a corneal procedure to solve both presbyopia and cataract problems. Up till now, laser is used mainly by younger generation to correct their vision, but yet patients with cataracts are unable to use it to remove cataracts and it is definitely an issue worth looking into for the next generation. 

First time watching a vision correction surgery

Before starting to work in GS Eye Center, my image of vision correction laser surgery is only laser and eye but I have never thought deeply about the actual operation process especially for someone who is not from ophthalmology backgroundJ. My cousins and friends had the surgery already and I have received positive feedbacks from them regarding the surgery. 

After my first step into the surgery room, I had to change my uniform and be careful with what I touched. I have butterfingers and I am not a meticulous person. Our eye center has MEL 80, VISX and IntraLase machines, and all these have to be tested every morning before any surgery begins. The machines aren’t huge but the sound VISX and MEL 80 give out during laser process is loud with light burning smell. Of course as a beginner, I wasn’t expecting anything like that and I was shocked to hear the sound. It’s like…a road construction worker drilling a hole in the ground.

After testing, I moved around watching my co-workers preparing the instruments needed for the surgeries on that day and taking notes of what was used during the surgeries. At 11 am, the first patient stepped into the operation room for LASEK using VISX. After explaining the procedure to the patient, eye drops were given to sterilize and anesthetize the eyes. The patient was then brought into the operation room and after lying on the bed, the nurse covered the face area except the eyes with a waterproof drape. The laser sound was then demonstrated for the patient while the nurse washed the eyes with balanced salt solution.

After washing, surgeon came in and he started by using a speculum to keep the eyes open. Then the surgeon used a scrapper to scrap the top layer of the cornea and the laser procedure started. The whole procedure only lasted for less than a minute per eye and eye was washed with saline. Eye drops were used to soothe the eye and speed up corneal healing process. Finally the operated eye was covered with a contact lens (0.0) to enable the cornea to heal without any possibility of inflammation. The surgeon then removed the speculum and repeated the same process to the other eye.

After the procedure, the patient was brought to the recovery room to rest for about 10 minutes and the surgeon checked on the eyes again and set up a follow-up appointment before the patient left the hospital. It was definitely amazing seeing someone walking in the center with glasses and getting out of the center without glasses. The whole procedure was painless but the eyes will start tearing for the next three days as it was a LASEK procedure and eye drops have to be used for at least 2-4 weeks.

Well I think it is definitely worth it especially if I compare it with buying glasses and contact lenses every year, I will be able to save more money in long term run.