Tuesday, June 12, 2012

Abstract: PRK, scraping vs alcohol

Before you read this PRK abstract (yes, it really is there, just scroll way down), here's a brief lesson in the history of elective refractive surgery to place it all in context:

After the RK of the 80s/90s (where they put incisions in the cornea - which had some unfortunate long term problems that eventually came to light) came the first major excimer laser procedure: PRK, where they scrape off your epithelium (outermost layer of the cornea), shoot the laser at the now exposed cornea, and wait for the epithelium to grow back (which it does quite quickly though vision can be unstable for a while afterwards). Soon after came LASIK, where they cut a flap in the cornea - not just the top layer but right into the thick stuff - and laser what's underneath. LASIK quickly left PRK in the dust because it was far more marketable: Rapid visual recovery, little or no pain. Quick & easy for doctors, not too much follow-up care, happy patients, what's not to like. Whole industries were borne out of LASIK. Even better, wavefront lasers came along to which are even more marketing friendly ("Custom" treatment!) and probably even improving visual outcomes.

But that wasn't good enough: What do you do for the people who cannot safely get LASIK due to thin corneas or other risk factors? Poor things, what a shame for them to miss out. (And, later, another dilemma: What do doctors who are concerned about LASIK's long term complications even for low-risk patients do?)

Answer: Repackage PRK to make it sound, smell and feel more user-friendly. Incorporate bona fide clinical improvements if possible, reducing pain and improving rapidity of recovery if possible.

That's how things like "LASEK" "E-LASIK" and "Epi-LASIK" and a host of other procedures and euphemisms emerged. They're all just variations on the theme of PRK, with the main variable just what you do with the epithelium: Scrape it off? Soak it with alcohol and peel it off, and maybe lay it back down again? Laser it off? Or what? Doesn't matter too much as long as the name of the procedure rhymes with LASIK, right? Most patients don't understand the difference anyway. Just don't say PRK, because it rhymes with Ouch.

Of course, in a medical business not distinguished by its ethics, there will always be those who take full advantage of the confusion. I am reminded of the many, many patients I heard from a few years back who fell for the sleazy tactics of a well known and very auspicious sounding surgical practice in New York who "sold" people LASEK but really scraped it off (you don't scrape in LASEK). Amusingly, they were all given videos of their procedures, which of course they put up on YouTube to show off. Only a few of the savvier ones found out that they didn't actually get LASEK. Though, according to this abstract, maybe they should be glad? I dunno.

Anyway, the morals of this story are:

  • New technology is not always superior to old technology.
  • Buyer beware. Even if the peddler has a lot of letters after his/her name.
p.s. I'd really like to know what the 6-month and 12-month dry eye outcomes were in the study below. I noticed complications were measured out to 12 months but in the abstract, the dry eye outcomes were only stated as of 1 month.
p.p.s. Those who read right to the bottom and who know me best will no doubt notice with admiration (grin) that I somehow managed to stay off my soapbox about the military's involvement with refractive laser procedures.

A smooth corneal surface prior to laser ablation is important in order to achieve a favorable refractive outcome. In this study, we compare PRK outcomes following two commonly used methods of epithelial debridement: Amoils epithelial scrubber (brush) versus 20% ethanol (alcohol).
We reviewed records of patients who underwent wavefront-optimized PRK for myopia or myopic astigmatism between January 2008 and June 2010. Two treatment groups (brush vs. alcohol) were compared in terms of uncorrected distance visual acuity (UDVA), manifest refraction spherical equivalent (MRSE), corrected distance visual acuity (CDVA), and complications at postoperative months 1, 3, 6, and 12.
One thousand five hundred ninety-three eyes of 804 patients underwent PRK during the study period: 828 brush-treated eyes and 765 alcohol-treated eyes. At 6 months postoperatively UDVA was ≥20/20 in 94.7% of brush-treated eyes versus 94.4% of alcohol-treated eyes (P=0.907). At 1 month a higher percentage of brush-treated eyes maintained or gained one or more lines CDVA compared to alcohol-treated eyes (P=0.007), but there were no other differences in UDVA, MRSE, or CDVA at any point postoperatively. At 1 month 75.4% of brush-treated eyes versus 70.4% of alcohol-treated eyes were free of complications (P=0.032), and there were fewer brush-treated eyes with corneal haze (4.0% vs. 6.9%, P=0.012) and dry eye (8.9% vs. 14.4%, P=0.001). Although corneal haze was slightly more frequent in the alcohol group, most was trace and not significant.
Although alcohol-assisted PRK had more minor complications in the early postoperative period, including corneal haze and dry eye, results for both groups beyond 1 month were comparable. Lasers Surg. Med. © 2012 Wiley Periodicals, Inc.

Lasers Surg Med. 2012 Jun 1. doi: 10.1002/lsm.22036. [Epub ahead of print]
Sia RK, Ryan DS, Stutzman RD, Psolka M, Mines MJ, Wagner ME, Weber ED, Wroblewski KJ, Bower KS.
U.S. Army Warfighter Refractive Surgery Research Center at Fort Belvoir, Fort Belvoir Community Hospital, Fort Belvoir, Virginia 22060. rose.sia@us.army.mil.

Abstract: Sleep apnea, FES and dry eye

This is an interesting look at ocular surface disease as associated with floppy eyelid syndrome (FES), which is more common in people with sleep apnea. They're suggesting people with symptomatic FES be checked out for sleep apnea. 

But... look out for the flip side, which is that CPAP masks for sleep apnea treatment often cause dry eye symptoms by blowing air into the eyes, which is why Quartz and Onyix silicone eye shields were invented (though they are now also used widely for dry eye, lagophthalmos etc).

The aim of this study was to assess the correlation between ocular surface changes and disease severity in patients with obstructive sleep apnea-hypopnea syndrome (OSAHS).
Two hundred eighty patients with OSAHS were compared with respect to the presence of a floppy eyelid syndrome (FES), Ocular Surface Disease Index (OSDI) questionnaire, the corneal fluorescein staining stages, the Schirmer I test, and tear film break-up time (TBUT) values.
Based on the apnea-hypopnea index, the presence of FES was detected at the following rates: 23.1 % in non-OSAHS group (A), 41.7 % in mild group (B), 66.7 % in moderate group (C), and 74.6 % in severe group (D); severe and moderate stage of FES was found in groups C and D and mild stage of FES in group B (p<0.01). OSDI questionnaire values were as follows: group A, 12.57±17.64; group B, 22.90±16.78; group C, 45.94±22.03; and group D, 56.68±22.85(p<0.01). Schirmer values were as follows: group A, 10.76±3.58 mm; group B, 9.83±2.53 mm; group C, 7.73±2.42 mm; and group D, 6.97±2.15 mm (p<0.01). The TBUT values were as follows: group A, 10.53±3.64 s; group B, 9.46±2.40 s; group C, 7.29±2.13 s; and group D, 6.82±2.20 s (p<0.01). Corneal staining scores are as follows: 0.26±0.60 in group A, 0.40±0.71 in group B, 0.98±0.72 in group C, and 1.14±0.90 in group D, and the differences were statistically significant among the groups(p<0.01).
OSAHS, particularly the moderate and severe forms, is associated with low Schirmer and TBUT values and high scores in OSDI questionnaire and corneal staining pattern stage. The presence of FES is observed as a practically constant finding in OSAHS. If complaints such as burning, stinging, and itching which can be commonly observed in middle-aged patients are accompanied by FES, the patient should be evaluated for sleep disorders. We speculate that appropriate treatment of OSAHS may result in better control of these symptoms.

Sleep Breath. 2012 Jun 5. [Epub ahead of print]
Acar M, Firat H, Acar U, Ardic S.
Department of Ophthalmology, Ministry of Health, Ankara Diskapi Yildirim Beyazit Training and Research Hospital, Ankara, Turkey, m_acar@hotmail.com.

happy eyes

Hurray, my PROSE lenses are back at last. After a week and a half of squinting and grimacing, I am soooo relieved.