Experimental Verification of Computational Methods to Calculate Magnification in Refractive Surgery

Conventional versus custom ablation in photorefractive keratectomy: Randomized clinical trial

“…If they did not, postoperative elimination of the minifying effect of spectacles could offset the negative effect of HOAs on contrast sensitivity function. 16,17 Higher-order aberrations increased significantly in our study. The increase was chiefly the result of an increase in coma and spherical aberrations, which had an equal effect on most postoperative HOAs in both groups.…”

“…The area under the log contrast sensitivity function (AULCSF) was calculated as described by Applegate et al 15 Because the contrast sensitivity function was checked with best distance correction with spectacles, the preoperative values were adjusted for the minification effect to make them comparable to those measured postoperatively. 16,17 …”

Prospective Evaluation of Mesopic Night Vision and Night Vision Goggle Visual Acuity After Photorefractive Keratectomy (PRK)

“…For example, a AD myopic patient corrected with spectacles to emmetropia, compared with PRK surgical correction to emmetropia, is expected to show an improvement of 0.02 log MAR (1 letter) on high contrast VA tests. As mentioned, a greater effect with low contrast charts, e.g., the CS Rabin SLCT chart, can be anticipated that is probably closer to 1 line (10 letters) or 0.1 log CS (54,64). Therefore, a small beneficial effect from PRK correction in myopes, due to the increased relative magnification in the retinal image at the corneal plane, should be expected when comparing their post-PRK VA or CS to their best-corrected pre-PRK performance.…”

Effect of higher order aberrations on contrast sensitivity function in myopic eyes

“…30 To eliminate the minifying effect of corrective spectacles, we applied the method described by Applegate and colleagues. 24,25 Therefore, we might have to consider other factors such as higher order aberrations or abnormality of retinal function to explain the infl uence of the severity of myopia on CSF.…”

“…In the present study, therefore, spatial frequencies were adjusted by correcting the magnifi cation effects caused by moving the refractive correction from the spectacle plane to the corneal plane (Appendix). 24,25 After CSF was measured, cycloplegic refraction was determined by using 1 drop of 1% cyclopentolate. Thereafter, when the pupil diameter was greater than 6 mm, aberrometry was performed with a Zywave II aberrometer with Zywave software version 5.2 (Bausch & Lomb, Rochester, NY, USA) in a dark room.…”