Corneal higher order aberrations changes after lasik for correction of hypermetropia and mixed astigmatism

Hypermetropia is a defect of vision caused by an imperfection in the eye [often when the eyeball is too short or when the lens cannot become round enough], causing difficulty focusing on near objects. As an object moves toward the eye, the eye must increase its power to keep the image in focus on the retina. If the power of the cornea and lens is insufficient, as in hyperopia, the image will appear blurred. to report the visual outcome and keratometric values, in addition to the corneal higher order aberration after laser instu keratomillusis for the correction of hypermetropia and mixed astigmatism. This prospective observational comparative study comprised 60 eyes of 30 individuals. Wavefront analysis for each cornea was performed; Root Mean Square [RMS] of anterior corneal higher order aberrations and separate types of corneal higher order aberrations using Zernike Polynomials were analyzed for all patients pre and postoperatively. 60 eyes of 30 individuals [28 [46.7%] women and 32 [33.3%] men]. 32 [53.3%] right eyes and 28 [46.7%] were left eyes. Mean patient age was 36.46+ 13.99 years [range: 16 to 54 years]. Mean sphere was+3.30+ 1.55 D [range:+1.0 to+5.5 D] Mean cylinder was-1.31+ 1.45 D [range:-4.75 to+0.5 D]. Spherical aberration [SA] preoperatively was 0.21 [+ .05] and postoperatively-0.02 [+ .24] and a mean difference of 0.23 and p value of 0.01. Coma aberration preoperatively was 0.29 [+ .10] and postoperatively 0.44 [+ .32] and a mean difference of-0.15 and p value of 0.86. While Root Mean Square [RMS] of higher order aberrations [HOA] preoperatively was 0.43 [+.10] and postoperatively-0.66 [+ .29] with a mean difference of 0.22 and p value of 0.05. Conventional LASIK increases all corneal higher order aberrations with induced aberrations increasing with the magnitude of refractive correction

Early detection of keratoconus by higher order abberations

Keratoconus is a bilateral, non-inflammatory and progredient corneal ectasia. It is a progressive disease ultimately affecting both eyes, although only one eye may be affected initially. The Aim of This Study is to detect subclinical keratoconus in patients whose fellow eyes are diagnosed with early keratoconus using corneal higher order aberrations. This prospective observational comparative study comprised 72 eyes of 36 individuals that were divided into three groups, normal eyes as control[group A] and eyes with recently diagnosed cases with keratoconus [group B] and fellow clinically free eyes of those patients [group C]. Wavefront analysis for each cornea was performed; Root Mean Square [RMS] of anterior corneal higher order aberrations and separate types of cornea! higher order aberrations using Zernike Polynomials were analyzed. Spherical aberration in group A was 0.206 [+ .074] and in group C-0.17 [+ .737] and a mean difference of-0.376 and p value of 0.01. Coma aberration in group A was 0.233 [+ .146] and in group C-2.33 [+ .903] and a mean difference of 2.097 and p value of 0.00. While RMS of higher order aberration in group A was 0.373 [+ .124] and in group C 2.69 [+ .930] and a mean difference of 2.325 and p value of 0.00. Also comparison of group A [normal patients] and group B [keratoconus suspect patients] revealed statistically non significant difference in spherical aberrations and highly statistically significant difference in coma, and RMS of higher order aberrations values. Anterior corneal surface higher order aberrations [coma aberrations and RMS of HOAs] are significantly higher in eyes with keratoconus than in normal eyes. While the Spherical aberrations are significantly lower than in normal individuals