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
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