to determine the accuracy of the holladay 1 , hoffer q , sanders - retzlaff - kraff ( srk)/t , and srk ii iol power calculation formulas in patients with high myopia in a subset of indian population .
this study was conducted at sadguru netra chikitsalaya , chitrakoot , madhya pradesh , india .
all consecutive patients attending our out patient department ( opd ) for phacoemusification with axial length ( al ) more than 24.5 mm ( range 24.75 - 32.35 mm ) between may 2009-october 2009 ( in all patients hydrophilic acrylic foldable within the bag iol was implanted ) . 
 pre - existing astigmatism > 3.0 diopters ( d)corneal scarkeratoconuscomplications significantly affecting the refractive status ( vitreous loss with iol implanted in sulcus or anterior chamber , high wound induced astigmatism ) . 
  pre - existing astigmatism > 3.0 diopters ( d ) complications significantly affecting the refractive status ( vitreous loss with iol implanted in sulcus or anterior chamber , high wound induced astigmatism ) . in our study , keratometry measurements were retrieved from records and a scan applanation ultrasonography was done on echorule2 and analyzed .
the implanted iol power was used to calculate the predicted postoperative refractive error by four commercially available iol formulas : srk ii , srk - t , holladay 1 , and hoffer q. with each formula , the mean error ( me ) was calculated from the difference between the formula predicted refractive error and actual postoperative refractive error . the spherical equivalent
was measured by a single trained optometrist using an autorefractor and subjective retinoscopy 1 - 2 months after cataract surgery .
repeated measures anova tests were done after making bonferroni corrections to have pair - wise comparisons between the formulas and p < 0.05 was considered as significant .
this study was conducted at sadguru netra chikitsalaya , chitrakoot , madhya pradesh , india .
all consecutive patients attending our out patient department ( opd ) for phacoemusification with axial length ( al ) more than 24.5 mm ( range 24.75 - 32.35 mm ) between may 2009-october 2009 ( in all patients hydrophilic acrylic foldable within the bag iol was implanted ) . 
 pre - existing astigmatism > 3.0 diopters ( d)corneal scarkeratoconuscomplications significantly affecting the refractive status ( vitreous loss with iol implanted in sulcus or anterior chamber , high wound induced astigmatism ) . 
  pre - existing astigmatism > 3.0 diopters ( d ) complications significantly affecting the refractive status ( vitreous loss with iol implanted in sulcus or anterior chamber , high wound induced astigmatism ) . in our study , keratometry measurements were retrieved from records and a scan applanation ultrasonography was done on echorule2 and analyzed .
the implanted iol power was used to calculate the predicted postoperative refractive error by four commercially available iol formulas : srk ii , srk - t , holladay 1 , and hoffer q. with each formula , the mean error ( me ) was calculated from the difference between the formula predicted refractive error and actual postoperative refractive error . the spherical equivalent
was measured by a single trained optometrist using an autorefractor and subjective retinoscopy 1 - 2 months after cataract surgery .
repeated measures anova tests were done after making bonferroni corrections to have pair - wise comparisons between the formulas and p < 0.05 was considered as significant .
all consecutive patients attending our out patient department ( opd ) for phacoemusification with axial length ( al ) more than 24.5 mm ( range 24.75 - 32.35 mm ) between may 2009-october 2009 ( in all patients hydrophilic acrylic foldable within the bag iol was implanted ) .

 pre - existing astigmatism > 3.0 diopters ( d)corneal scarkeratoconuscomplications significantly affecting the refractive status ( vitreous loss with iol implanted in sulcus or anterior chamber , high wound induced astigmatism ) . 
 
pre - existing astigmatism > 3.0 diopters ( d ) complications significantly affecting the refractive status ( vitreous loss with iol implanted in sulcus or anterior chamber , high wound induced astigmatism ) . in our study , keratometry measurements were retrieved from records and a scan applanation ultrasonography was done on echorule2 and analyzed .
the implanted iol power was used to calculate the predicted postoperative refractive error by four commercially available iol formulas : srk ii , srk - t , holladay 1 , and hoffer q. with each formula , the mean error ( me ) was calculated from the difference between the formula predicted refractive error and actual postoperative refractive error . the spherical equivalent
was measured by a single trained optometrist using an autorefractor and subjective retinoscopy 1 - 2 months after cataract surgery .
repeated measures anova tests were done after making bonferroni corrections to have pair - wise comparisons between the formulas and p < 0.05 was considered as significant .
forty three eyes of 43 patients with axial length more than 24.5 mm in our set - up were retrospectively studied .
the keratometry in most of the patients ( 81% ) was within the normal range of 42.0 - 46.0 d. overall performance of all the formulas in al more than 24.5 mm showed a tendency to cause a hyperopic refractive error post - operatively [ table 1 ] .
overall performance of formulas in eye with al>24.5 mm holladay 1 caused the smallest me , + 0.24 d. fifty three percent of patients had mean absolute error less than 1.00 d. the hoffer q and srk - t caused a little larger hyperopic shift with mes of + 0.58d and + 0.92 d. srk ii caused the largest hyperopic error + 1.23 d. [ table 1 ] .
pair - wise comparisons between different formulas shows that p value between different formulas is significant ( p < 0.05 ) implicating that holladay 1 with least me is significantly different from other formulas and have better performance in patients with al more than 24.5 mm when compared to srk - t , srk ii , hoffer q [ table 2 ] .
pair - wise comparisons measure : me ( mean error ) the performance of each formula in al subcategory in eyes with al between 24.5 - 26.5 mm also found holladay 1 as the best formula [ table 3 ] .
performance of formulas in eye with axial length 24.5 - 26.5 mm pair - wise comparisons between different formulas in a subset of patients with a al 24.5 - 26.5 mm shows that holladay 1 ( me = + 0.4320 d ) and hoffer q ( me = + 0.4695 d ) are comparable , p value not being significant [ table 4 ] .
our preliminary results showed that in our patients with axial myopia with als longer than 24.50 mm , the holladay 1 provided the best predictive result and the hoffer q was comparable to holladay 1 for al 24.5 - 26.5 mm for iol power calculation .
this agrees with the results in several studies in which better performances were found in cases with long eyes with the holladay 1 formula than the srk ii formula .
olsen and co - authors reported that the holladay formula is more accurate than the srk ii . in a study conducted by stopyra , in which a study of patients with al 24.51 - 26.72 mm and found holladay 1 formula was the most accurate with 88.5% of the patients achieving full visual acuity ( 1.0 on snellen ) after cataract surgery .
stopyra also found srk / t formula satisfactory with 63.9% of the patients achieving full visual acuity on snellen but only 36.1% of the patients achieved full visual acuity using hoffer q. kijima et al .
, report the best results using the holladay and srk / t in the midrange al ( 24.5 - 26.9 mm ) group and the srk / t or l - srk in the long al ( longer than 27.0 mm ) group .
tsang cs and co - authors also reported best results in patients with al 25.0 mm using hoffer q and holladay 1 and srk - t were comparable with srk ii being least accurate and in patients with al > 28.0 mm they found holladay 1 and srk / t more accurate than hoffer q. narvaez and co - authors also reported better performance of these formulas when compared with srk - ii . in studies by bang and co - authors on al > 27.0 mm and wang and co - authors on al > 25.0 mm using iol master reported that haigis formula is the best .
ghanem and el - sayed reported that in patients with high axial myopia , the performance of srk - t , hoffer - q , holladay-2 , and haigis formulas are comparable in low plus  powered iol implantation and haigis formula is the best formula when minus power iol is implanted .
however , we did not find performance of srk - t formula better in indian myopic population .
our recommendation is to avoid using the srk ii and srk / t formula for iol power calculation in eyes with axial myopia in indian population with al longer than 24.50 mm . in our study , all four formulas had a tendency to cause a postoperative hyperopic refraction .
our study had some limitations : ( a ) it was a single center retrospective study and ( b ) surgeons , and time of the postoperative refraction were not standardized .
to conclude , the results of our study provide useful information to aid the choice of iol power in patients with high axial myopia in indian population during our daily practice with holladay 1 being the most accurate and srk ii and srk / t to be avoided .
 efficacy of intraocular lens power calculation formulas in a subset of indian myopic population . retrospectively reviewed 43 patients who underwent phacoemulsification with high axial length ( al ) ( > 24.5 mm , range 24.75 - 32.35 mm ) . 
 the power of the implanted intraocular lens ( iol ) was used to calculate the predicted post - operative refractive error by four formulas : sanders - retzlaff - kraff ( srk ii ) , srk / t , holladay 1 , and hoffer q. the predictive accuracy of the formulas was analyzed by comparing the difference between the  actual  and  predicted  postoperative refractive errors . 
 repeated measures analysis of variance ( anova ) tests were done to have pair - wise comparisons between the formulas and p < 0.05 was considered significant . 
 a subcategory of axial length 24.5 - 26.5 mm was also tested . 
 holladay 1 , hoffer q and srk / t formulas showed a slight tendency toward resultant hyperopia , with mean error of + 0.24 diopters ( d ) , + 0.58 d , and + 0.92 d , respectively . the holladay 1 formula provided the best predictive result overall . 
Aim
Materials and Methods
Design: Retrospective study
Inclusion criteria
Exclusion criteria
Results
Discussion