April 2007

 

COVER FEATURE

 

Cataract Surgery

To omit or not to omit?


by Enette Ngoei EyeWorld Staff Writer

   

Considering intracameral dilating agents versus topical drops

eye after injecting epi-Shugarcaine

The same eye several minutes after injecting epi-Shugarcaine. The increased dilation is especially obvious when looking at the nasal AK, which is now well within the pupillary margin.

Source: Joel K. Shugar, M.D.

Eye of a Flomax patient

Eye of a Flomax patient before injecting Epi-Shugarcaine. Note that an already fashioned AK is co-linear with the nasal border of the pupil. Source: Joel K. Shugar, M.D.

The pupils dilate almost instantaneously upon injection, eliminating the hassle of repeated drops prior to surgery, according to Alan S. Crandall, M.D., professor of ophthalmology, University of Utah School of Medicine, Salt Lake City, but 95% of surgeons still have not gone the way of intracameral dilating agents.

“Most doctors are still using the 2.5% phenylephrine (various manufacturers) and then 1% Cyclogyl (cyclopentolate HCl, Alcon, Fort Worth, Texas) … and they’ll be putting them in probably at least three different sets, five minutes apart prior to surgery,” said Nick Mamalis, M.D., professor of ophthalmology, Moran Eye Center, University of Utah, Salt Lake City.

Unlike most of his colleagues, Dr. Crandall and a number of other surgeons do not dilate patients at all prior to cataract surgery. Instead, they use a combination of intracameral lidocaine and add a little epinephrine, which provides a quicker response because it hits the dilating muscle.

Having omitted topical dilation for five years, Dr. Crandall said there are myriad reasons why he prefers this method of dilation over traditional topical drops. Besides saving time, intracameral dilating agents cause less irritation on the cornea because you’re putting fewer chemicals into the eye, he said. “This is especially good for diabetics because the diabetic cornea is very sensitive to the medication it often breaks down very easily,” Dr. Crandall said.

Intracameral dilating agents also produce dilation as good as that of tropical drops, and they undilate quicker, Dr. Crandall said. And visual acuity on day one is better because the pupils are not dilated, he added.

His list goes on.

And if personal recommendations aren’t enough, studies continue to demonstrate the effectiveness of intracameral dilating agents. One recent study published in the January issue of the Journal of Cataract & Refractive Surgery evaluated pupil dilation by an intracameral injection of 1% Xylocaine (nonpreserved lidocaine, AstraZeneca PLC, London) during phacoemulsification cataract extraction and compared the results to those using conventional topical mydriatics.

Aminollah Nikeghbali M.D., Eye Research Center Rassoul Akram Hospital, Iran University of Medical Sciences, Tehran, and colleagues conducted a prospective comparative case series study that included 57 patients who were given topical mydriatics (30 eyes) or intracameral lidocaine (27 eyes) to dilate the pupil for phacoemulsification and IOL implantation. “The topical group received three drops of cyclopentolate 1% and phenylephrine 5% given five minutes apart, starting 60 minutes before surgery. The intracameral group received preservative-free lidocaine 1% (0.2 to 0.3 mL) injected just before the procedure began. No epinephrine was added to the irrigating solution,” the researchers wrote in the study. The researchers measured the horizontal pupil diameter before and after pupil dilation using the same caliper in both groups. And they recorded total surgical time, need for a mydriatic agent during the procedure, and subjective surgical performance. The researchers reported that the mean pupil dilation was 4.52 mm +/– 0.08 (SD) in the intracameral group and 4.06 +/– 0.09 mm in the topical group. They wrote the difference between groups was statistically significant (P = 0.001). In addition, the researchers found no significant difference between groups in the overall subjective surgical performance (P = 0.74).

“No patient in the intracameral group and two patients in the topical group required an intracameral mydriatic injection,” the research-ers reported.

They concluded that during phacoemulsification, intracameral preservative-free lidocaine 1% provided rapid, effective mydriasis comparable to that of topical mydriatics.

Why don’t more surgeons use it?

Despite the personal recommendations and studies suggesting its effectiveness, surgeons still have their own beliefs about intracameral dilating agents.

Topical dilating agents give a wider dilation than intracameral injections, Dr. Mamalis said. Howard Fine, M.D., clinical professor, Casey Eye Institute, Oregon Health & Science University, Portland, Ore., said, “It may be that the pupil doesn’t stay dilated as long with [intracameral dilating] agents compared to pre-op drops, and that would be advantageous for better vision in the innediate post-op period.”

“However, we add anti-inflammatory, antibiotic, anesthetic, as well as mydriatic cycloplegic drops to a solution that surgigel pledgets soak in prior in being placed under the upper lid for 20 minutes, pre-op. So, just eliminating the mydriatic cycloplegic drops has very little advantage.”

In fact, Dr. Crandall said, doctors just don’t believe it works. But perhaps the most compelling reason why eye surgeons aren’t readily making a switch to intracameral dilating agents is that old habits die hard.

“Surgeons, in general, don’t like to make changes,” Dr. Crandall said.

Even Joel K. Shugar, M.D., M.S.E.E., Perry, Fla., the inventor of the intracameral Epi-Shugarcaine to combat intra-operative floppy iris syndrome (IFIS), prefers not to rely on intracameral dilation. Dr. Shugar first invented Shugarcaine to serve as an intracameral anesthesia and then Epi-shugarcaine, which contains epinephrine, which further improves dilation. Although people have used regular Shugarcaine to aid in dilation as well as analgesia, Epi-Shugar-caine is the most effective to use for intracameral dilation, Dr. Shugar said. However, he added: “I mostly use pledgets pre-op. Instead of putting a bunch of drops inside the eye, you mix all the drops you want to use together and put a little absorbent strip in the inferior conjunctival forynx. But I will use intracameral Epi-Shugarcaine to supplement dilation if the dilation is inadequate or if the iris has any tendency to flop.” Although Dr. Shugar said there is a growing trend toward omitting pre-op dilation, he admitted to the advantages of safety by not using phenylephrine and the decrease in the amount of medications the cornea is subjected to pre-op, he said, “For me, the biggest advantage of pre-operative dilation is that the beginning of the case I know how big the pupil is going to get, so I can plan the use of such instruments as the Beehler dilator if necessary. What I’m doing now works really well for me, so I’m not compelled to change.”

Taking a stab at it

Still, perhaps one good opportunity surgeons may use to explore intracameral dilation without completely doing away with their usual practices is in cases in which patients are on Flomax (tamsulosin hydrochloride, Boehringer Ingelheim GmbH, Germany) or have IFIS. “The advantage of Epi-Shugarcaine for that is that it’s got several dilating agents in it to kind of super-dilate the eye and a much higher percentage of the epinephrine in it so it helps hold the pupil during these difficult floppy iris syndrome procedures,” Dr. Crandall said.

Dr. Shugar, who’s been using Shugarcaine since 1997, said, “What it represents is a form of intracameral lidocaine that’s much safer and more effective than using just 1% lidocaine out of the bottle because 1% lidocaine out of the bottle is too acidic.

“It can have a pH as low as six, so it’s not healthy for the epithelium. There have been studies showing that something has to have a pH of at least 6.5, and that acidity also makes it sting more when it’s instilled inside the eye.”

The recipe for Shugarcaine is one part 4% unpreserved lidocaine (and three parts BSS Plus (Alcon, Fort Worth, Tex.), and the recipe for Epi-Shugarcaine in whole cc quantities is 9 cc of BSS Plus, 3 cc of 4% preservative-free lidocaine, and 4 cc of bisulphate free 1:1000 epinephrine. When used for intracameral dilation, the patient should have at least one drop of 1% Mydriacyl (tropicamide, Alcon, Fort Worth, Texas) at least a half-hour before surgery, Dr. Shugar said.

Editors’ note: Dr. Crandall is a consultant for Alcon (Fort Worth, Texas). Dr. Mamalis performs contract resarch for Alcon. Drs. Fine and Shugar have no financial interests related to their comments.

Contact Info:

Crandall: 801-581-2352, alan.crandall@hsc.utah.edu.

Fine: 541-687-2110, hfine@finemd.com

Mamalis: 801-581-6586, nick.mamalis@hsc.utah.edu

Shugar: 850-584-2778, stareyes@gtcom.net.

       
To omit or not to omit? To omit or not to omit?
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