this is a nonrandomized prospective comparative case study on 57 eyes seeking refractive surgery who were not indicated for laser corneal refractive surgery . patients with refraction error between 2.00 d and 14.50 d who could use both artiflex and artisan , were free to choose the type of the lens . other patients underwent artisan implantation . ophthalmic examinations before surgery included cyclo - refraction , uncorrected visual acuity ( ucva ) , best - corrected visual acuity ( bcva ) , topography , keratometry , endothelial cell count , pupil diameter , and anterior chamber ( ac ) depth measurement . according to patient history and examination , patients who had the following conditions underwent piol implantation surgery : insufficient corneal thickness for refractive corneal surgery , inappropriate corneal curvature and topography , high myopia more than 8 d which could not undergo corneal refractive surgery , negative history of any previous refractive surgery , sufficient internal ac depth ( 3 mm or greater ) , no history of intraocular pressure raise and endothelial cell density of 2500 cell / mm or more . lens dioptric power was calculated by van der heijde formula , using refractive error , refractive cylinder power , ac depth , and topographically derived keratometry values . emmetropia was the target power of the surgery , when the precise emmetropic lens was not available our choice was to a slight residual myopia . all surgeries were performed under general anesthesia , for artisan lens implantation , a superior 5 or 6 mm length corneal incision was created at the 12 o'clock position , followed by performing two stab incisions located at 2 and 10 o'clock . the lens was inserted into the ac under protection of intracameral ophthalmic viscoelastic material injection . artiflex lens implantation was performed similarly , although the lens was inserted through a 3.2 mm incision . other steps were carried out same as artisan implantation ; finally , the wound was closed by stromal hydration without the necessity of suturing . one year after surgery , cyclo - refraction , bcva , ucva , cs , hoa and patient satisfaction were assessed . cs was determined by csv-1000 chart , and refraction was obtained with topcon auto refractometer and then modified by subjective refraction . night vision , day vision , halo , photophobia , dryness , pain , and patient satisfaction were assessed by questionnaire with numerical scales ( 0 = weak , 1 = moderate , 2 = good , 3 = excellent for day and night vision 0 = none , 1 = mild , 2 = moderate , 3 = severe for halo , photophobia , dryness , and pain ) . the chart consists of four rows corresponding to spatial frequencies of 3 , 6 , 12 , and 18 cycles per degree ( cpd ) . the distance between the patient and the chart was 2.5 m. the test was performed with the patients monocular bcva to eliminate the effects of sia and residual post - operative refraction . the aberrations analyzed were classified in terms of hoa , vertical trefoil , vertical coma ; horizontal trefoil , horizontal coma , quatrefoil , second astigmatism , and fourth order spherical aberration . comparison between artisan and artiflex data were analyzed using parametric paired student 's t - test , p < 0.05 was considered statistically significant . this is a nonrandomized prospective comparative case study on 57 eyes seeking refractive surgery who were not indicated for laser corneal refractive surgery . patients with refraction error between 2.00 d and 14.50 d who could use both artiflex and artisan , were free to choose the type of the lens . other patients underwent artisan implantation . ophthalmic examinations before surgery included cyclo - refraction , uncorrected visual acuity ( ucva ) , best - corrected visual acuity ( bcva ) , topography , keratometry , endothelial cell count , pupil diameter , and anterior chamber ( ac ) depth measurement . according to patient history and examination , patients who had the following conditions underwent piol implantation surgery : insufficient corneal thickness for refractive corneal surgery , inappropriate corneal curvature and topography , high myopia more than 8 d which could not undergo corneal refractive surgery , negative history of any previous refractive surgery , sufficient internal ac depth ( 3 mm or greater ) , no history of intraocular pressure raise and endothelial cell density of 2500 cell / mm or more . lens dioptric power was calculated by van der heijde formula , using refractive error , refractive cylinder power , ac depth , and topographically derived keratometry values . emmetropia was the target power of the surgery , when the precise emmetropic lens was not available our choice was to a slight residual myopia . all surgeries were performed under general anesthesia , for artisan lens implantation , a superior 5 or 6 mm length corneal incision was created at the 12 o'clock position , followed by performing two stab incisions located at 2 and 10 o'clock . the lens was inserted into the ac under protection of intracameral ophthalmic viscoelastic material injection . artiflex lens implantation was performed similarly , although the lens was inserted through a 3.2 mm incision . other steps were carried out same as artisan implantation ; finally , the wound was closed by stromal hydration without the necessity of suturing . one year after surgery , cyclo - refraction , bcva , ucva , cs , hoa and patient satisfaction were assessed . cs was determined by csv-1000 chart , and refraction was obtained with topcon auto refractometer and then modified by subjective refraction . night vision , day vision , halo , photophobia , dryness , pain , and patient satisfaction were assessed by questionnaire with numerical scales ( 0 = weak , 1 = moderate , 2 = good , 3 = excellent for day and night vision 0 = none , 1 = mild , 2 = moderate , 3 = severe for halo , photophobia , dryness , and pain ) . the chart consists of four rows corresponding to spatial frequencies of 3 , 6 , 12 , and 18 cycles per degree ( cpd ) . the distance between the patient and the chart was 2.5 m. the test was performed with the patients monocular bcva to eliminate the effects of sia and residual post - operative refraction . the aberrations analyzed were classified in terms of hoa , vertical trefoil , vertical coma ; horizontal trefoil , horizontal coma , quatrefoil , second astigmatism , and fourth order spherical aberration . comparison between artisan and artiflex data were analyzed using parametric paired student 's t - test , p < 0.05 was considered statistically significant . a total of 57 eyes were included in the study ; of which , 24 eyes were in artisan group and 33 eyes were in artiflex group . the preoperative spherical equivalent ( se ) and bcva were obtained and compared , no statistically significant difference was noticed in the mean preoperative se ( 10.39  8.43 d in artisan group and  10.39  2.29 d in artiflex group ; p = 0.999 ) and bcva of two groups ( 0.25  0.21 logarithm of the minimum angle of resolution [ logmar ] for artisan group and 0.19  0.18 logmar for artiflex group ; p = 0.56 ) . the mean postoperative se was  0.93  1.28 d in the artisan group and  0.54  0.82 in the artiflex group , no significant difference was seen in in postoperative se between two groups ( p = 0.19 ) . one year after the operation , 54% of artisan - treated eyes ( 15/24 ) and 75.7% ( 25/33 ) of artiflex treated eyes were within  1.00 d of intended emmetropia [ figs . 1 and 2 ] . in the artisan group , 37.5% of the treated eyes ( 9/24 eyes ) had three or more snellen line improvement of postoperative bcva , 12.5% ( 3/24 eyes ) had two snellen line improvement and 25% ( 6/24 eyes ) had loss of two or more snellen lines . in the artiflex group , 51.5% of the treated eyes ( 17/33 eyes ) had three or more snellen line improvement of bcva , 15.1% ( 5/33 eyes ) had two line improvement , and no eyes had loss of two or more snellen lines of bcva [ fig . 3 ] . the bar graph shows the postoperative defocus equivalent 1 year after artisan ( a ) and artiflex ( b ) implantation bar graph of change in best - corrected visual acuity from the preoperative examination to postoperative examination in terms of the number of snellen line change . artisan ( a ) , artiflex ( b ) mesopic contrast sensitivity at spatial frequencies of 3 , 6 , 12 and 18 degree per cycles in this study , total hoa in artisan - treated eyes was significantly greater than artiflex - treated eyes ( p = 0.044 ) with a mean hoa of 0.44  0.15 root mean square ( rms ) for artisan and 0.35  0.15 rms for artiflex . there was no significant difference in the vertical trefoil , vertical coma , horizontal trefoil , horizontal coma , quatrefoil , second astigmatism , and fourth order spherical aberration . the evaluation of cs in mesopic conditions showed higher cs in artiflex - treated eyes at three spatial frequencies 6 , 12 , and 18 cpd ( p = 0.003 , p = 0.007 , and p = 0.00 , respectively ) , and no significant difference was seen between two lenses at 3 cpd spatial frequency [ table 1 and fig . contrast sensitivity data after phakic intra - ocular lens implantation subjective comparison of day and night vision in artisan versus artiflex treated eyes the mean of sia was 1.65  0.82 d in artisan group , and 1.31  1.05 in artiflex group , which showed no statistically significant difference between the groups ( p = 0.19 ) . in a subjective evaluation of day vision , all patients of the artiflex group reported good and excellent vision , in artisan group , 71% of patients reported good and excellent vision , whereas 7.1% complained of weak day vision . in the assessment of night vision , 50% of patients treated with artiflex reported good and excellent vision and no one complained of weak night vision . in artisan group , 71.4% reported good and excellent vision , whereas 21.4% reported weak night vision [ fig . subjective comparison of halo , photophobia , pain and dryness in artisan versus artiflex treated eyes among artiflex treated eyes , 50% reported moderate halos and in the artisan group 40% reported moderate to severe halos . about 12.5% of artiflex treated eyes experienced moderate photophobia , whereas 35.7% of artisan treated eyes experienced moderate to severe photophobia . in the artiflex group , only 12.5% of treated eyes caused mild pain , whereas 36.7% of artisan treated eyes caused mild to moderate pain . moderate to severe dryness was reported in 25% of eyes treated with artiflex , whereas no artisan treated eye experienced moderate or severe dryness [ fig . 6 ] . the bar graph of patient 's satisfaction in artisan versus artiflex groups satisfaction more than 60% was reported in 100% of patients in artiflex group versus 60% of patients in artisan group [ fig . the bar graph presents the postoperative spherical equivalent 1 year after artisan ( a ) and artiflex ( b ) implantation . as it is well - confirmed , the recently food and drug administration approved pmma artisan piol is an effective mean for the correction of refractive errors and have been shown to have acceptable safety and efficacy . however , studies have revealed instances of significant induced astigmatism , attributed to the larger incisions performed in the implantation of the artisan lens . artiflex iris - fixated piol , a foldable version of artisan , is an improvement of the iris - supported piol concept , with a lower incidence of sia . artiflex piol haptics are made of pmma and the foldable optical zone is made of silicon . the main purpose of this investigation is to evaluate the differences in optic quality between rigid piol versus flexible piol by comparing wavefront aberration , cs and patient satisfaction in patients who underwent artisan and artiflex iris - fixated iol implantation . in this study , mean postoperative residual se were 0.93  1.28 d and  0.54  0.82 d in the artisan and artiflex group , respectively , no significant difference was seen in postoperative se between two groups ( p = 0.19 ) . about 54% of artisan group and 75.7% of artiflex group were within  1.00 d of intended emmetropia . in a previous study , 58% and 83.9% of artisan and artiflex group had a residual postoperative se within  1.00 d , which was significantly better in artiflex group . another study reported that emmetropia ( 1.00 d ) was obtained in 60% and 91.7% of artisan and artiflex group , respectively , the difference was statistically significant [ table 2 ] . percentage of postoperative refraction within1.00 d of intended emmetropia in a retrospective comparative case series on 27 eyes , postoperative se was within  0.5 d in 76.2% and 85.7% of artisan and artiflex treated eyes , respectively . in a study of evaluating the outcome of iris - claw piol in fifty high myopic eyes , postoperative se was evaluated , which showed that 38% and 68% of the eyes were in the range of  0.5 d and  1.00 d , respectively . mean postoperative ucva was 0.34  0.25 logmar in artisan group and 0.12  0.15 logmar in artiflex group . mean postoperative bcva was 0.21  0.13 and 0.06  0.08 logmar in the artisan and artiflex groups , respectively [ table 3 ] . the differences of ucva and bcva in two groups were statistically significant ( p = 0.00 ) . in another study , postoperative bcva between artisan and artiflex groups was not significantly different ( p = 0.9 ) . postoperative visual acuity ( logarithm of the minimum angle of resolution ) in artisan group versus artiflex group in this study , although vertical trefoil , vertical coma , horizontal trefoil , horizontal coma , secondary astigmatism , quatrefoil and fourth order spherical aberration were not significantly different between the artiflex and artisan groups , total hoa was higher in artisan group , that may be due to the slight differences in each component , which totally increases the hoa ( p = 0.044 ) . in a previous study , assessment of hoas after implantation of rigid versus foldable iris - fixated lenses , showed a significant decrease in postoperative spherical aberration among artiflex group and a significant increase in postoperative spherical aberration in artisan group . in both groups , vertical trefoil and spherical aberration were higher in artisan group , p = 0.039 and p = 0.001 , respectively . assessment of cs in mesopic condition showed no significant difference between two groups at 3 cpd spatial frequency . cs was significantly higher in artiflex - treated eyes at three spatial frequencies 6 , 12 and 18 cpd ( p = 0.003 , p = 0.007 , and p = 0.00 , respectively ) . a previous investigation showed that mesopic cs was slightly better in artiflex group in comparison with artisan group , but the difference was not statistically significant , they also measured photopic cs function and found that both groups had poorer performance compared to the normal range . performance with the artisan lens was slightly better than performance with artiflex under photopic conditions , but worse under mesopic conditions ; neither differences were statistically significant . in this study , we have used artisan iol for patients not eligible for the available artiflex ( six myopic eye more than 14.5 d and one hyperopic eye ) , comparison of this two groups may have some biases because of other probable conditions such as retinal involvement or amblyopia , which can alter the results , this was one of our study limitations . in this study , 25% of patients with artisan lens lost two or more lines of bcva , we called the patients back and examined them again carefully , we recognized that in one patient both eyes had refractive error postoperatively in spite of implanting a lens with the same power of his preoperative se improvement in bcva was not seen with correction of this refractive error by trial - frame . in the other patients , we could not find any reason for the decrease in the bcva , unless considering pigment deposition on the iol as a reason for the visual loss .
aim of study : the aim of this study is to assess wavefront aberration and contrast sensitivity ( cs ) after implantation of foldable iris claw  artiflex- and rigid iris claw 
 artisan- phakic intraocular lenses ( piols).materials and methods : a nonrandomized prospective comparative case study was performed on 57 eyes ; of which , 54 were myopia and 3 were hyperopia . 
 twenty - four patients had artisan piol implantation and 33 had artiflex piol implantation . 
 higher - order aberration ( hoa ) and cs were obtained 1 year after surgery.results:total hoa in artisan group was greater than artiflex group ( p = 0.044 ) with a mean hoa of 0.44  0.15 root mean square ( rms ) for artisan and 0.35  0.15 rms for artiflex . 
 although , there were no significant differences in the vertical trefoil , vertical coma , horizontal trefoil , horizontal coma , secondary astigmatism , quatrefoil , and fourth order spherical aberration in two groups . 
 cs in mesopic conditions was better in artiflex - treated eyes at three spatial frequencies of 6 , 12 , and 18 cycles per degree ( cpd ) ( p = 0.003 , p = 0.007 , and p = 0.00 , respectively ) , and no significant difference was seen between two lenses at 3 cpd.conclusion:although the components of hoa were not significantly different between two groups , total hoa was higher in artisan group , which may be due to the slight differences in each component , increasing the hoa as a total . 
 cs was significantly better in artiflex group .