Tscherning Operating Principle
Wavefront Technology
Working in the same visible spectrum as the human eye, the ALLEGRO Analyzer® device is designed for wavefront measurements on the basis of the Tscherning principle.
In order to perform measurements according to the Tscherning principle, an image of regular measurement spots are projected onto the retina and captured by a light sensitive camera. The distortion of the light spots on the retina in relation to the reference light bundle is calculated and the wavefront error displayed.
An automatic image validation function ensures that the image has been taken properly and that all measurement spots are valid. The application of this principle allows the ALLEGRO Analyzer® Device to transfer valid data to the laser system and helps minimize the risk of inaccurate treatments.
The ALLEGRO Analyzer® Device utilizes visible light to perform the measurements. Additional off-line calculations and factoring for chromatic errors are not required.
An automatic capturing mode ensures that only centered measurements will be taken into account. Minor decentrations are detected and registered along with the pupil diameter and other relevant values.
The Alcon ALLEGRO Analyzer® Device is aligned with the ALLEGRETTO WAVE® laser systems and uses an accurate eye-tracking system which provides safety and centration.
Myopia:
a. Approval of the premarket approval application is for the WaveLight® ALLEGRETTO WAVE® / ALLEGRETTO WAVE® Eye-Q Excimer Laser System to perform LASIK treatments in patients 18 years of age or older for the reduction or elimination of myopic refractive errors up to -12.0 diopters (D) of sphere with and without astigmatic refractive errors up to -6.0 D; and in patients with documented evidence of a stable manifest refraction defined as less than or equal to 0.50 D of preoperative spherical equivalent shift over one year prior to surgery.
b. LASIK is an elective procedure with the alternatives including but not limited to eyeglasses, contact lenses, photorefractive keratectomy (PRK), and other refractive surgeries.
c. Approval of the application is based on clinical trials in the United States with 901 eyes treated, of which 813 of 866 eligible eyes were followed for 12 months. Accountability at 3 months was 93.8%, at 6 months was 91.9%, and at 12 months was 93.9%.
d. The studies found that of the 844 eyes eligible for the uncorrected visual acuity (UCVA) analysis of effectiveness at the 3-month stability time point, 98.0% were corrected to 20/40 or better, and 84.4% were corrected to 20/20 or better without spectacles or contact lenses.
e. The clinical trials showed that the following subjective patient adverse events were reported as “moderate to severe” at a level at least 1% higher than baseline of the subjects at 3 months posttreatment: visual fluctuations (12.8% at baseline versus 28.6% at 3 months).
f. Long-term risks of LASIK for myopia with and without astigmatism beyond 12 months have not been studied.
g. Note that the complete name for this ophthalmic laser is “WaveLight® ALLEGRETTO WAVE® / ALLEGRETTO WAVE® Eye-Q Excimer Laser System for laser assisted in-situ keratomileusis (LASIK) treatments of myopic refractive errors up to -12.0 diopters (D) of sphere with and without astigmatic refractive errors up to -6.0 D at the spectacle plane.”
Hyperopia:
a. Approval of the premarket approval application is for the WaveLight® ALLEGRETTO WAVE® / ALLEGRETTO WAVE® Eye-Q Excimer Laser System to perform LASIK treatments in patients 18 years of age or older for the reduction or elimination of hyperopic refractive errors up to +6.0 diopters (D) of sphere with and without astigmatic refractive errors up to 5.0 D at the spectacle plane, with a maximum manifest refraction spherical equivalent (MRSE) of +6.0 D; and in patients with documented evidence of a stable manifest refraction defined as less than or equal to 0.50 D of preoperative spherical equivalent shift over one year prior to surgery, exclusive of changes due to unmasking latent hyperopia.
b. LASIK is an elective procedure with the alternatives including but not limited to eyeglasses, contact lenses, photorefractive keratectomy (PRK), and other refractive surgeries.
c. Approval of the application is based on clinical trials in the United States with 290 eyes treated, of which 100 of 290 eligible eyes were followed for 12 months. Accountability at 3 months was 95.2%, at 6 months was 93.9%, and at 12 months was 69.9%.
d. The studies found that of the 212 eyes eligible for the uncorrected visual acuity (UCVA) analysis of effectiveness at the 6-month stability time point, 95.3% were corrected to 20/40 or better, and 67.5% were corrected to 20/20 or better without spectacles or contact lenses.
e. The study showed that the following subjective patient adverse events were reported as “much worse” by at least 1% of the subjects (in order of increasing frequency) at 6 months post final treatment: glare from bright lights (3.0%); night driving glare (4.2%) light sensitivity (4.9%); visual fluctuations (6.1%); and halos (6.4%).
f. Long term risks of LASIK for hyperopia with and without astigmatism beyond 12 months have not been studied.
g. Note that the complete name for this ophthalmic laser is “WaveLight® ALLEGRETTO WAVE® / ALLEGRETTO WAVE® Eye-Q Excimer Laser System for laser assisted in-situ keratomileusis (LASIK) treatments of hyperopic refractive errors up to +6.0 diopters (D) of sphere with and without astigmatic refractive errors up to 5.0 D with a maximum manifest refraction spherical equivalent (MRSE) of +6.0 D.”
Mixed Astigmatism:
a. Approval of the premarket approval application is for the WaveLight® ALLEGRETTO WAVE® / ALLEGRETTO WAVE® Eye-Q Excimer Laser System to perform LASIK treatments in patients 21 years of age or older for the reduction or elimination of naturally occurring mixed astigmatism of up to 6.00 D at the spectacle plane; and in patients with documentation of a stable manifest refraction defined as less than or equal to 0.50 D of preoperative spherical equivalent shift over one year prior to surgery.
b. LASIK is an elective procedure with the alternatives including but not limited to eyeglasses, contact lenses, photorefractive keratectomy (PRK), and other refractive surgeries.
c. Approval of the application is based on clinical trials in the United States with 162 eyes treated, of which 111 were eligible to be followed at 6 months. Accountability at 1 month was 99.4%, at 3 months was 96.0%, and at 6 months was 100.0%.
d. The studies found that of the 142 eyes eligible for the uncorrected visual acuity (UCVA) analysis of effectiveness at the 3-month stability time point, 95.8% achieved acuity of 20/40 or better, and 67.6% achieved acuity of 20/20 or better without spectacles or contact lenses.
e. The clinical trials showed that the following subjective patient adverse events were reported as “moderate to severe” at a level at least 1% higher than baseline of the subjects at 3 months post-treatment: sensitivity to light (43.3% at baseline versus 52.9% at 3 months); visual fluctuations (32.1% at baseline versus 43.0% at 3 months); and halos (37.0% at baseline versus 42.3% at 3 months).
f. Long term risks of LASIK for mixed astigmatism beyond 6 months have not been studied.
g. The safety and effectiveness of LASIK surgery has ONLY been established with an optical zone of 6.0 - 7.0 mm and an ablation zone of 9.0 mm.
h. Note that the complete name for this ophthalmic laser is “WaveLight® ALLEGRETTO WAVE® / ALLEGRETTO WAVE® Eye-Q Excimer Laser System for laser assisted in-situ keratomileusis (LASIK) treatments of naturally occurring mixed astigmatism of up to 6.00 D at the spectacle plane.”
Wavefront-Guided Treatment of Myopia:
a. Approval of the premarket approval application is for the WaveLight® ALLEGRETTO WAVE® / ALLEGRETTO WAVE® Eye-Q Excimer Laser System used in conjunction with the WaveLight® ALLEGRO Analyzer® device. The device uses a 6.5 mm optical zone, a 9.0 mm ablation/treatment zone, and is indicated for wavefront-guided (WFG) laser assisted in-situ keratomileusis (LASIK): 1) for the reduction or elimination of up to -7.00 diopters (D) of spherical equivalent myopia or myopia with astigmatism, with up to -7.00 D of spherical component and up to 3.00 D of astigmatic component at the spectacle plane; 2) in patients who are 18 years of age or older; and 3) in patients with documentation of a stable manifest refraction defined as ≤0.50 D of preoperative spherical equivalent shift over one year prior to surgery.
b. LASIK is an elective procedure with the alternatives including but not limited to eyeglasses, contact lenses, photorefractive keratectomy (PRK), traditional LASIK and other refractive surgeries.
c. Approval of the application is based on a randomized clinical trial in the United States with 374 eyes treated; 188 with wavefront-guided LASIK (Study Cohort) and 186 with Wavefront Optimized® LASIK (Control Cohort). 178 of the Study Cohort and 180 of the Control Cohort were eligible to be followed at 6 months. In the Study Cohort, accountability at 1 month was 96.8%, at 3 months was 96.8%, and at 6 months was 93.3%. In the Control Cohort, accountability at 1 month was 94.6%, at 3 months was 94.6%, and at 6 months was 92.2%.
d. The studies found that of the 180 eyes eligible for the uncorrected visual acuity (UCVA) analysis of effectiveness at the 6-month stability time point in the Study Cohort, 99.4% were corrected to 20/40 or better, and 93.4% were corrected to 20/20 or better without spectacles or contact lenses. In the Control Cohort, of the 176 eyes eligible for the uncorrected visual acuity (UCVA) analysis of effectiveness at the 6-month stability time point, 99.4% were corrected to 20/40 or better, and 92.8% were corrected to 20/20 or better without spectacles or contact lenses.
e. The clinical trials showed that the following subjective patient adverse events were reported as “moderate to severe” at a level at least 1% higher than baseline of the subjects at 3 months post-treatment in the Study Cohort, light sensitivity (37.2% at baseline versus 47.8% at 3 months) and visual fluctuations (13.8% at baseline versus 20.0% at 3 months). In the Control Cohort, halos (36.6% at baseline versus 45.4% at 3 months) and visual fluctuations (18.3% at baseline versus 21.9% at 3 months).
f. Long term risks of wavefront-guided LASIK for myopia with and without astigmatism beyond 6 months have not been studied.
g. Note that the complete name for this ophthalmic laser is “WaveLight® ALLEGRETTO WAVE® / ALLEGRETTO WAVE® Eye-Q Excimer Laser System used in conjunction with the WaveLight® ALLEGRO Analyzer® device. The device uses a 6.5 mm optical zone, a 9.0 mm ablation/treatment zone, and is indicated for wavefront-guided (WFG) laser-assisted in-situ keratomileusis (LASIK): 1) for the reduction or elimination of up to -7.00 diopters (D) of spherical equivalent myopia or myopia with astigmatism, with up to -7.00 D of spherical component and up to 3.00 D of astigmatic component at the spectacle plane; 2) in patients who are 18 years of age or older; and 3) in patients with documentation of a stable manifest refraction defined as ≤0.50 D of preoperative spherical equivalent shift over one year prior to surgery.”