OHM Effect of low-to-moderate degrees of refractive astigmatism on Contrast sensitivity and Reading speed in pseudophakic eyes Shetal M. Raj, DO, MS, Abhay R. Vasavada, MS, FRCS, Vaishali Vasavada, MS, Viraj A. Vasavada, MS, M.R. Praveen, DO The authors have received travel expense reimbursement from Alcon Laboratories, USA Iladevi Cataract and IOL Research Center, Ahmedabad, India

To evaluate effect of low to moderate degrees of refractive astigmatism (0.5 to 0.75 diopters (D)) on low and high contrast sensitivity and reading speed in pseudophakic eyes. Purpose

Prospective, controlled, observational study Materials and Methods Study Population 40 eyes of 40 pseudophakic patients with single-piece monofocal hydrophobic acrylic IOL Monofocal IOL BCVA of 20/20 Refractive astigmatism of 0.5 and 0.75D Inclusion criteria Study Design-

1. ETDRS acuity using CSV chart 100%, 25%, 10% contrast. 2. Contrast sensitivity using the Vector Vision charts photopic, mesopic and glare conditions 3. Reading acuity on Radner reading charts LogRAD score Mean reading speed Maximum reading speed Observations All observations were done monocular with - spherical equivalent (uncorrected cylinder) and - with sphere and cylinder correction (corrected cylinder)

1. Distance contrast acuity Results 0.5 cyl (n=21)0.75 cyl (n=19) S.E.Corr.P value S.E.Corr.P value 100% % % S.E. = Spherical equivalent (uncorrected cylinder) Corr. = Corrected sphere and cylinder (Corrected cylinder) P = Paired sample T test

2. Contrast sensitivity: photopic Results 3 cpd6 cpd12cpd18 cpd S.E.CorrS.E.Corr.S.E.Corr.S.E.Corr. 0.5 cyl (n=21) P value cyl (n=19) P value S.E. = Spherical equivalent (uncorrected cylinder) Corr. = Corrected sphere and cylinder (Corrected cylinder) P = Wilcoxon signed ranks paired test

Contrast sensitivity: mesopic Results 3 cpd6 cpd12cpd18 cpd S.E.CorrS.E.CorrS.E.CorrS.E.Corr 0.5 cyl (n=21) P value cyl (n=19) P value S.E. = Spherical equivalent (uncorrected cylinder) Corr. = Corrected sphere and cylinder (Corrected cylinder) P = Wilcoxon signed ranks paired test

Contrast sensitivity: glare conditions Results 3 cpd6 cpd12cpd18 cpd S.E.CorrS.E.CorrS.E.CorrS.E.Corr 0.5 cyl (n=21) P value cyl (n=19) P value S.E. = Spherical equivalent (uncorrected cylinder) Corr. = Corrected sphere and cylinder (Corrected cylinder) P = Wilcoxon signed ranks paired test

3. Reading acuity on Radner reading charts Results LogRAD ScoreMean Reading Speed Max Reading Speed S.E.Corr.S.E.Corr.S.E.Corr. 0.5 cyl (n=19) P value cyl (n=21) P value S.E. = Spherical equivalent (uncorrected cylinder) Corr. = Corrected sphere and cylinder (Corrected cylinder) P = paired sample t test

The performance of eyes with 0.5 diopter cylindrical error fully corrected resulted in significantly better: – Distance contrast acuity at 100% and 25% – Photopic contrast at 6, 12, 18 cpd – Mesopic contrast at 6 cpd – Glare contrast at 3, 6 cpd – Mean reading speed Summary The performance of eyes with 0.75 diopter cylindrical error fully corrected resulted in significantly better: – Distance contrast acuity at 100%, 25% and 10% – Photopic contrast at 3, 6, 12, 18 cpd – Mesopic contrast at 3, 6 cpd – Glare contrast at 3, 6, 18 cpd – Mean and maximum reading speed

Correction of astigmatism as low as 0.50 and 0.75 diopters improves the visual performance Surgeons must strive to adopt techniques and IOLs that eliminate the pre-existing astigmatism, such as microincision phacoemulsification approach and using Toric IOLs Implications

High and Low contrast acuity, contrast sensitivity, Reading acuity was significantly better when correcting 0.5 and 0.75 dioptres of refractive astigmatism as compared to correcting with spherical equivalent and not giving cylindrical correction in the spectacles. Conclusion