I'm looking at either Pelleve or Thermi to assist with the loss of collagen under my eyes. Which is best?

Generally radio-frequency energy applied correctly does help to reduce wrinkles around the eyes and tighten skin. I find the Pelleve very patient friendly and with great outcomes. See if your provider will package the whole session plan as one cost rather than each time

Pellleve (tm) and Thermi(tm) are exactly the SAME technology (RF, or radiofrequency), and at the same pulse and wavelength.  Yes, it will take at least 3 sessions (actually, our office has a package price consisting of 3 sessions 7-10 days apart,+ 2 moes at monthly intervals (total of 5). While we usually do the whole face, only doing the eyes (lida and under) is an option.Best,Michael P Goodman, MDDavis, CA, USA

Thank you for your question. You submitted a question without a photo, and state you had a Thermi procedure, but you didn’t see a huge difference. You say you understand it takes 3 to 4 sessions to see a difference, but you also became aware of a cost difference between Thermi and Pellevé, and you want to know if these are same technologies, or if there’s a difference.
I can give you some guidance for this type of concern. A little background: I’m Board-certified cosmetic surgeon, and Fellowship-trained oculofacial plastic and reconstructive surgeon. I’ve been in practice in Manhattan and Long Island for over 20 years, and I have been part of this continuous evolution of thermal energy devices for the past 20 plus years, beginning with the original CO2 lasers back in the early to mid 90s.
You raise a very good question, which actually brings into focus a broader issue I have some opinion about. Let’s first understand what Thermi and Pellevé are - both are radiofrequency technology devices that induce a certain amount of heat to create skin changes, essentially collagen remodeling. If you watch the procedures being demonstrated, they look exactly the same, and for all intents and purposes, they are the same. From a scientific perspective, they’re both handheld devices that apply energy to the skin through radiofrequency technology to generate heat to a target temperature. Since the science behind these devices is essentially is the same from the way the heat is generated and the goal of the tissue response. There’s a core concept that when skin is heated up to a certain level, it responds with the generation something called heat shock proteins, and a process of collagen breakdown and remodeling that results in a favorable response such as the improvement of fine lines and wrinkles. The challenge for the consumer is unfortunately, there is a real race between companies to dominate and create a brand awareness rather than educating the public about what the science behind the device is, and letting the physician guide patients with what any of these particular devices can do.
From my perspective as a practicing doctor, these devices are tools, and the patient comes to me with a particular problem and I don’t have to be locked into just one tool - I can use a combination of approaches. In principle, you are looking at similar devices doing similar things. When I look at someone who wants improvement of wrinkles, let’s say the under eye area, I don’t just say ok there is only one device to treat them. I can combine modalities because typically there a lot of things that can be improved at the same time. I always say the whole is greater than the sum of its parts. It’s not unusual to have issues with pigmentation, the surface of the skin, and volume loss. To solve those issues we also include another modality such use of PRP, or platelet-rich plasma. Platelet-rich plasma is derived from your blood, and is used to stimulate collagen and create remodeling of skin, without inducing heat.
One of the things I should point out is although the skin can be heated to a certain temperature, the response of the skin is not consistent between people; it’s like going to the gym - everyone may do exactly the same workout, but everyone will develop a different degree of muscle growth. The same thing applies to skin-  multiple factors, whether its age, ethnicity, tissue type - too many factors to really articulate altogether when you don’t look at the whole picture. The patient’s medical background, their sun exposure history, their smoking history - there are a lot of factors, so often people get really disappointed when they see a device on television promoted aggressively as the next miracle, then they go have these procedures and don’t get results.
Often there’s a commoditization of devices, so in many situations the physician actually isn’t involved in the planning of the whole procedure. The patient comes to a spa of some kind, and a non-physician says okay this is the device we use for that, what kind of package would you like?
I look at things a little more globally - I l would consider using platelet-rich plasma, I possibly a hyaluronic acid filler such as Restylane, to help with tear trough area or I maybe use a neurotoxin, like Botox® to help with fine lines and wrinkles, and put into perspective the more realistic potential benefits of these devices. In our practice, we have Pellevé and I should disclosed we don’t have Thermi at this time. We also have a 1064 YAG laser, Q switch laser, fractional CO2 laser, Erbium laser, so we have a lot of technology, and so there is no limitation in providing solutions for our patients.  
What we don’t do is jump on whatever is new and exciting for that moment, because I’ve seen a lot of hype for devices. It’s more about the devices and the manufacturer’s interest in selling and leasing those devices to doctors, then within another year or so, they are selling or leasing a different version of the device making the previous device obsolete. It creates a bit of tension between the patient and the physician, but remember the physician is the one most qualified to give you guidance and give you a whole plan, even though there may be a price difference between the two devices coming from the different potential of practitioners.
Get a good understanding as to what outcome you’re looking for, what is realistic with either device, and also understand what your other options are. As far as answering the question about the technology and the outcomes, these devices, are as far as I am concerned, are pretty much the same. Although manufacturers will always try to differentiate one from another in ways that might be significant from a sales point of view, for a physician from a instrument point of view as a tool, there is no difference for me which of these radiofrequency devices I would use to accomplish a target heating goal to generate collagen.
I think you should either seek the attention of the physician you’re going to for this device or this treatment, or find a physician who can guide you. Have a more global plan before you continue doing more packages or looking at more brands, otherwise you’ll be like many people bouncing from one practitioner to another, reacting to these strong messaging of one miracle device to another. I hope that was helpful, I wish you the best of luck, and thank you for your question.