September 2018


MKO Melt for cataract anesthesia

by Rich Daly EyeWorld Contributing Writer

MKO Melt
Source: Chris Bender, CRNA


The opportunities and obstacles clinicians see in the emerging anesthesia option

Clinicians experienced with the newer anesthesia option of MKO Melt (Imprimis Pharmaceuticals, San Diego) say it has important advantages and some limitations.
MKO Melt is a form of sublingual sedation for cataract and other surgery named for its medications—midazolam (3 mg), ketamine HCl (25 mg), and ondansetron (2 mg). Patients place it under their tongue prior to surgery and feel the effects within a couple of minutes. Full effect takes place around 10 minutes and lasts about 45 minutes to an hour, said Michael Greenwood, MD, Vance Thompson Vision, Fargo, North Dakota.
“It has a nice synergy with the ketamine and the midazolam to provide analgesia,” said John Berdahl, MD, associate professor of ophthalmology, University of South Dakota. “Specific to cataract surgery, patients have a tendency to look at the light more and squint less during the surgery period. The ketamine also provides a mild euphoria, which from surgical experience is better for the patient.”
Dr. Berdahl, who uses MKO Melt in more than 99% of his cataract patients, doses primarily by age with consideration of ways to plan for anxiety level and prior use of sedatives. For the vast majority of patients—including high-risk patients—he does not start an IV.
However, if the patient has a very high level of anxiety, Dr. Berdahl will saline lock an IV as a backup in case it’s needed.


The advantages of MKO Melt seen by Chris Bender, CRNA, in private practice, Sioux Falls, South Dakota, are that it can be used without starting an IV and to help start an IV in the case of a severe needle phobia.
Because the melts are given earlier in the preop area and have a slower onset than IV medications, by the time patients are transported to the operating room, they are comfortable and less able to “ramp up” their anxiety, which leads to a smooth overall experience, Mr. Bender said.
For Dr. Greenwood, who uses the melt for almost all of his intraocular surgeries, including cataracts, MIGS, DMEK, and refractive lens exchanges, the primary advantage is not needing to place an IV. 
“That saves the patient time from having to get a needle stick and also time from having to have it removed,” said Dr. Greenwood, who opted for the melt in his own phakic IOL surgery and has used it in procedures on close relatives.
The patient flow benefits include allowing the staff to do other work and help the patient have an overall better experience, which reduces the chance for a delay due to waiting for an IV to be placed, Dr. Greenwood said.
The MKO Melt is titratable, which allows giving one, one and a half, or two to patients depending on a variety of factors. Age is one of the biggest factors affecting titration at Dr. Greenwood’s surgical center. 
“Patients are comfortable, relaxed, but can still follow instructions if needed, such as turning their head or looking to the side during various MIGS procedures,” Dr. Greenwood said about the melt, which has a quick onset and a stable and consistent level of sedation throughout procedures.
Dr. Berdahl has found patients given the melt tend to “gaze at the light and keep their eye more still at the time of surgery.”
Additionally, the elimination of the need to remove an IV, a smooth patient recovery, and their ability to quickly leave the postop area once all assessments are met are other advantages Dr. Berdahl sees.
Dr. Greenwood has seen additional patient benefit from the anti-nausea effect of ondansetron. He also views as an advantage the melt’s availability to be ordered in 503B, which allows bulk orders without the need for individual prescriptions.


The melt’s primary disadvantage, Mr. Bender said, is the difficulty to redose or supplement the sedation once the procedure is started.
That concern was echoed by the surgeons.
“The disadvantages are that there isn’t a safety blanket of the IV in the hand, however, anesthetists and nurses are quite adept at giving an IV in the operating room if it’s needed, which is rare,” Dr. Berdahl said.
The need to start an IV occurs in fewer than 1% of Dr. Berdahl’s patients.
The only time Dr. Greenwood supplements the melt with an IV is in his cataract plus DMEK cases because there is a chance such surgeries will take a few extra minutes, and the IV allows the patient to get some additional anesthesia, if needed. About 5% of the patients get additional medications.
“The times I don’t use MKO Melt are when I am going to do a block for a PKP or other complex surgery,” Dr. Greenwood said. “These patients have an IV for
the block so we use traditional anesthetic.”
Mr. Bender said there is a learning curve to using the MKO Melt.
“Once practitioners get a good understanding of how patients respond to the dosing and timing of administration, supplementation with IV medications becomes rare,” Mr. Bender said.

Patient feedback

A number of patients have sought out Dr. Berdahl’s practice due to severe needle phobias and because they heard he offered cataract surgery without the need for an IV.
“In general, patients enjoy it,” Dr. Greenwood said. “They are comfortable, relaxed, and don’t recall much from the surgery.
Among the few comments Dr. Greenwood has received is that some patients don’t like the taste, but they much prefer that over insertion of an IV.
“They enjoy not having the IV,” Dr. Greenwood said.

Editors’ note: Mr. Bender and Dr. Berdahl have financial interests with Imprimis Pharmaceuticals. Dr. Greenwood has no financial interests related to his comments.

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