The purpose of the study presented in the article is to study the factors that correlate with improved best spectacle corrected visual acuity, or BSCVA, after LASIK treatment. The cornea is the part of the eye that helps focus light in order to create an image on the retina. The eyes cornea works in much the same way that the lens of a camera focuses light to create an image on film. The bending and focusing of light is also known as refraction. Usually the shape of the cornea and the eye are not perfect. This causes the image on the retina to be out of focus, blurred or distorted. These imperfections in the focusing power of the cornea of ones eye are called refractive errors. There are three primary types of refractive errors. These are the myopia or near sightedness, hyperopia or far sightedness and astigmatism. Persons with myopia have more difficulty seeing distant objects as clearly as near objects. Persons with hyperopia have more difficulty seeing near objects as clearly as distant objects. Astigmatism is a distortion of the image on the retina caused by irregularities in the cornea or lens of the eye. Usually, combinations of myopia and astigmatism or hyperopia and astigmatism happen. The use of glasses and contact lenses are designed to compensate for the eyes imperfections. There are surgical procedures aimed at improving the focusing power of the eye are called refractive surgery. One of them is LASIK surgery. LASIK is the acronym for Laser Assisted in Situ Keratomileusis. It is a type of refractive laser eye surgery with the aid of digital microscope performed by ophthalmologists for correcting cases of myopia, hyperopia, and astigmatism. In LASIK surgery, precise and controlled removal of corneal tissue by a special laser with the help of digital microscope reshapes the cornea changing its focusing power.
The study presented in the article was a nonrandomized, prospective clinical trial. It involved 850 eyes from 480 patients. All these patients have undergone LASIK surgery with the aid of digital microscope for cases of myopia, hyperopia, and mixed astigmatism. The methods of the study were discussed in the article. The mean preoperative spherical equivalent refraction was -3.75+/-4.82 diopters D with a range of -13.88 to 6.00 D. From the said studied population, 72 eyes from 43 patients were found to have improved BSCVA 6 months after LASIK treatment. This involved including 22 amblyopic eyes. All of the patients underwent LASIK with the NAVEX platform. The article tells that in the study, these eyes were analyzed to evaluate factors that correlated with improved BSCVA. The pre and postoperative BSCVA, refraction, pupil diameter, corneal topography, asphericity, total aberrations, and higher order wavefront aberrations were analyzed. All wavefront aberrations were measured using the NIDEK Optical Path Difference Scan aberrometer preoperatively and at 6 months postoperatively. The results of the study showed that postoperatively, the mean sphere was -0.44 1.30 D (range: -4.50 to +2.50 D. The mean increase in BSCVA was 0.15+/-0.09 log MAR. The authors of the study also observed in the results that there was a statistically significant negative correlation between the increase in BSCVA and the preoperative BSCVA. They have also found that mixed astigmatic and highly myopic eyes are more likely to gain BSCVA after LASIK than moderately myopic and hyperopic eyes. The results further showed that in patients with myopia, the amount of BSCVA improvement correlated with the magnitude of the correction. Also, the induction of spherical aberration negatively correlated with the increase in BSCVA. All in all, they have noted that there were no significant differences between normal eyes and amblyopic eyes with respect to postoperative improvement in BSCVA. With all the results given, the study concluded that decreased preoperative BSCVA, lower total spherical aberration induction, and preoperative mixed astigmatism and high myopia correlate with an increase in BSCVA after LASIK. Read more on this subject