MYOPIAASTIGMATISMANISOMETROPIAANISEIKONIA-Srisofts.ppt

* ADVANTAGES OF SPECTACLES Economical Allow incorporation of prism,bifocals,pal which can be used for the management of esophoria or any accommodative disorders accompanying myopia Spectacles require less accommodation than contact lens for myopia that likelihood of accommodative asthenopia or near point blur in patients approaching presbyopia may be less * DISPENSING SPECTACLES IN HIGH MYOPIA High index lens materials Lighter lens materials Reduced eyesize of selected frames Minus lenticular lens designs * ADVANTAGES OF CONTACT LENS Contact lens provides cosmosis Large retinal image size and slightly better visual acuity in severe myopia * SURGICAL TREATMENT Epikeratophakia RK PRK ISCR Phakic IOL’S LASIK LASIK PRK RK ISCR Phakic IOL’S * Photorefractive Keratectomy (PRK) Involves direct laser ablation of corneal stroma after removal of corneal epithelium mechanically or using a laser beam. Done using Excimer laser MUNNERLYN EQN: depth of ablation (micrometer)=[diameter of optical zone(mm)]2 × 1/3power(Diopter) For myopic a large amount of ablation is done in central cornea than in the periphery. Give good results for -2D to -6D of myopia * LASIKLaser Assisted In situ Keratomileusis Method:Anterior flap of cornea is lifted with a keratome and excimer laser is used to sculpt the stromal bed to change the refractive error of eye Corrects 0.5 to 12D of myopia and upto 8D of astigmatism Guidelines:Age more than 18yrs BCVA better than 6/12 Stable refraction for last 1yr Absence of corneal disease ectasia Note: (1) In no case the residual bed thickness after the ablation should measure 250microns so as to avoid central corneal ectasia (2) Ideally the ablation should be done within 30sec of the preparation of flap * LASEKLaser subepithelial Keratomileusis Indications: Low myopia Irregular astigmatism LASIK complications in contralateral eye Thin corneal p