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Refractive surgery survey finds broad variations
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SAN DIEGO — In efforts to better understand the differences in refractive surgery and in an attempt to standardize the procedure on a worldwide basis, a survey was conducted by Kerry Solomon, MD, et al, and presented here at ASCRS. The comprehensive investigation highlighted demographics, practice patterns, surgical techniques, equipment used, preoperative, perioperative and postoperative procedures and complication rates.
The survey was sent to the entire worldwide membership of the ASCRS (n=8196) in February 2001. The survey had a response rate of 22% for North America, including Canada, Mexico and the United States.
Of all the refractive surgeons that responded to the survey, 19% have had refractive surgery performed on themselves. According to the surveyors, this represents a higher percentage than the incidence of refractive surgery in the general population, perhaps demonstrating the assurance that today’s eye surgeons have with current techniques. The only continent in which no eye surgeon reported having the surgery was Australia/New Zealand. Thirty percent of African eye surgeons that responded to the survey have had refractive surgery performed on themselves; 20% in Europe; and less than 20% among North and South American eye surgeons.
For those respondents who did not have surgery, the main reason was having no significant refractive error. Less than 20% of respondents either had concerns about side effects or did not know which eye surgeon should perform the procedure. Others claimed to be waiting for a better and safer procedure, or the procedure was too expensive, or the respondents didn’t have time to have the procedure.
Procedure volume
Of the surgeon respondents who are waiting for a better procedure to be performed on them, 57% said they perform less than five refractive procedures per week. Twenty-nine percent perform 5 to 10; 11% perform 11 to 20 procedures per week. Only 3% do more than 30 procedures per week. According to the investigators, this figure demonstrates that surgeons who are conservative with their eye care tend to be conservative with their refractive procedural volume. However, 11% would be classified as moderate volume and 3% would be considered high-volume surgeons. This is lower than the percent of moderate and high volume surgeons in the general population.
For other surgeons, 43% perform fewer than 5 procedures per week; 25% perform 5 to 10; 13% perform 11 to 20 procedures; 13% perform more than 30; and 6% perform 21 to 30 procedures per week.
Surgeons who have had a refractive procedure performed on them tended to do more refractive procedures per week compared with those doctors who have not had the procedure.
The laser most widely used for refractive procedures is from Visx, according to the survey. This number is biased, according to surveyors, because of the larger numbers of North American members of ASCRS. Almost 80% of North American respondents use a Visx laser.
Regarding microkeratome choice, 48% use the Hansatome from Bausch & Lomb. This number is also biased for the same reason, according to the study.
Comanagement compliance
As for complying with the American Academy of Ophthalmology/ASCRS comanagement guidelines, 45% of respondents claim they are following them. Thirty percent reportedly are not and 25% still do not know what the comanagement guidelines are.
According to survey results, refractive surgeons tend to comanage fewer than 25% of their patients regardless of whether they follow the comanagement guidelines (89% of surgeons who follow the guidelines vs. 80% who do not). The surgeons who comanage more than 25% of their patients, however, are two to three times more likely not to follow the comanagement guidelines, according to the survey. Interestingly, 1% of surgeon respondents who follow the guidelines and 3% who do not follow the guidelines comanage 100% of their patients.
Regarding prices charged for LASIK, 40% of North American respondents charge $1,500 to $1,999 per eye. Less than 30% of European respondent refractive surgeons charge this amount. Less than 10% of South American surgeons charge this amount.
There is some variation in LASIK pricing around the world. This is due, in part, to differences in currencies and to a lower total number in responses from countries outside North America. Sixty percent of respondents believe prices will remain the same and plan to keep them the same for the next 6 months.
Surgical technique
According to survey results, both 8.5-mm and 9.5-mm suction rings are commonly used in LASIK for myopia. The 9.5-mm ring size for myopia may be more frequently used due to the larger treatment zones offered by the newer scanning lasers. For hyperopia, a 9.5-mm suction ring is frequently preferred. Most (51.5%) respondents plan for a central keratometry reading of 45 D to 47 D.
The most common residual bed in LASIK for both primary and enhancement procedures is 250 µm to 274 µm of residual stromal tissue, according to the survey. Five percent of surgeons are willing to go deeper than 250 µm for their planned primary procedure. Twice that many are willing to go deeper than 250 µm of residual corneal tissue for planned enhancement procedures.
In terms of pupil size, 90% treat 8-mm pupils or less, while 10% of surgeons would treat pupils larger than 8 mm.
Most surgeons responding were comfortable treating a potential patient with a pupil size of 1.5 mm or more smaller than the ablative optical zone size. Some surgeons said they were comfortable treating pupil sizes of 2 mm or more larger than the optical zone size to be used. According to the researchers, this difference may be due to the use of lasers that treat with wider blend zones or due to treating patients with lower degrees of myopia.
According to the survey, bilateral surgery is performed more often in Africa, Asia and North America than in Australia/New Zealand, Europe and South America.
Monovision is used in fewer than 25% of patients treated worldwide. Monovision seems to be less commonly used in Asia, Australia/New Zealand and Europe.
In terms of the corneal flap, drying times vary between less than 1 minute and up to 5 minutes. Most surgeons who responded to the survey first check flaps soon after the procedure rather than on the first postoperative day.
It is more common in Australia/New Zealand and Europe to change microkeratome blades between eyes. Most surgeons in Asia and North America change blades between patients. It is more common in South America to change the blades after several patients have been treated.
Fluoroquinolones are the antibiotic of choice in North America, according to the survey. Aminoglycosides and other antibiotics are more frequently used outside of North America. The use of anti-inflammatory agents is similar between North America and other continents. However, strong steroids seem to be more frequently used after surgery in North America. Mild steroids and preserved non-steroidal agents appear to be more regularly used in other continents postoperatively. Non-steroidal anti-inflammatory drugs (NSAIDs), preserved and nonpreserved, appear to be used more commonly perioperatively in North America, whereas preserved NSAIDs are more commonly used postoperatively elsewhere.
Most refractive surgeons have not performed wavefront ablations; however, most suppose wavefront will increase the quality of vision. It is currently unclear whether surgeons would be willing to convert back to PRK if wavefront PRK is found superior to wavefront LASIK.
Complications
The most frequently reported complication after LASIK in the survey was dry eye, occurring 50% of the time or more often after surgery. Next in frequency was glare, followed by striae. The distribution of complications appears similar for high volume surgeons compared to the total response of all refractive surgeons.
According to the survey, surgeons believe there are many factors related to postop dry eye, including existing dry eyes, final corneal curvature, depth of ablation, lid margin disease, hinge location, size of flap used and optical zone size. The most common factor reported was previous history of dry eyes, something that most refractive surgeons are not measuring preoperatively. Most surgeons suppose that lid margin disease is also commonly related to dry eye.
Previous history of dry eye is the most common factor reported worldwide. Lid margin disease is the next most common factor reported worldwide. Surgeons in South America also believe final corneal curvature and other factors are associated more frequently.
Lid margin disease is the most commonly identified factor related to diffuse lamellar keratitis (DLK) worldwide. Microkeratome debris/oils, the autoclave, cleaning soaps for instruments and other factors including epithelial defects are also commonly reported factors. DLK appears to be multi-factorial, according to the survey.