Preoperative Biometry Research Articles

Intraoperative Aberrometry for IOL Selection

To review the clinical use, advantages, and potential limitations of intraoperative aberrometry (IA) and its application in cataract surgery in the normal, astigmatic, and atypical eye. The use of IA is similar to traditional preoperative biometry methods for intraocular lens (IOL) determination in short and normal eyes. The use of IA resulted in equivalent outcomes to modern formulas with optimized axial lengths in long eyes and exceeded traditional formulas. Improved outcomes compared to traditional methods were noted with the use of IA when used for both astigmatism correction and IOL determination in patients with a history of corneal refractive surgery. The greatest value in using IA is with atypical eyes. There is a surgeon learning curve with this technology to allow for optimal, consistent, and reproducible results. Despite the increasing popularity of IA, the number of published studies on this technology is limited.

Accuracy of Intraocular Lens Formulas in Eyes With Keratoconus

To evaluate the refractive accuracy of currentintraocular lens (IOL) formulas in eyes with keratoconus. Retrospective case series. Preoperative optical biometry, Pentacam topography, and postoperative outcomes were collected from eyes with keratoconus that had uncomplicated cataract surgery between 2014 and 2018 at a single institution. Exclusion criteria include postoperative best-corrected spectacle visual acuity worse than 20/40, multifocal lens, prior ophthalmic surgeries, and prior ocular trauma. The Hoffer Q, SRK/T, Holladay I, Holladay II, Haigis, and Barrett Universal II formulas were analyzed in each eye stratified by keratoconus severity. A total of 73 eyes were included. All formulas had a positive mean predicted error ranging from 0.10 to 4.38 diopters (D). The Barrett Universal II formula had the lowest median absolute error for stage I (n= 46, 0.445 D) and II (n= 22, 0.445 D) eyes, and the highest percentage of eyes with predicted error within ±0.50 D for both stage I (52%) and II (50%) eyes. In stage III eyes (n= 5), the Haigis formula had the lowest median predicated error (1.90 D) and the highest percentage of eyes with predicted error within ±0.50 D (40%). Corneal power measured by optical biometers was higher than measurements by Pentacam keratometry. All formulas tend to have a hyperopic surprise. The Barrett Universal II formula was the most accurate for mild to moderate disease. Pentacam keratometry may help avoid hyperopic outcomes.

Intraoperative Aberrometry Versus Preoperative Biometry for IOL Power Selection After Radial Keratotomy: A Prospective Study

To compare the accuracy of Optiwave Refractive Analysis (ORA) intraoperative aberrometry (Alcon Laboratories, Inc., Fort Worth, TX) with preoperative biometry in predicting residual refractive error after cataract surgery in eyes that underwent radial keratotomy. This was a prospective consecutive case series of patients with cataract and prior radial keratotomy. Each patient underwent a preoperative intraocular lens (IOL) power calculation using partial coherence interferometry (IOLMaster version 5; Carl Zeiss Meditec, Jena, Germany). For each eye, the Barrett True-K formula was used to select an IOL targeting emmetropia. Residual refractive error was predicted preoperatively using the SRK/T, Hoffer Q, Haigis, and Holladay formulas 1 and 2, and the ORA intraoperatively. Between 8 and 12 weeks after cataract extraction with IOL implantation, the postoperative refraction was compared with the preoperative and intraoperative predictions. The study comprised 52 eyes of 34 patients. The median absolute errors associated with each method were as follows: Barrett True-K formula (0.34), ORA aberrometer (0.53), and SRK/T (0.54), Hoffer Q (0.51), Haigis (0.54), SRK/T (0.57), and Holladay formulas 1 and 2 (0.44) (P = .08). The proportion of patients within ±0.50 diopters of the predicted error was 63.5%, 48.1%, 44.2%, 48.1%, 53.8%, 36.5%, and 57.7%, respectively (P = .03). No statistically significant difference was observed in the number of eyes with hyperopic outcomes (P = .68). In eyes with prior radial keratotomy surgery, the ORA aberrometer performance was similar to the Barrett True-K formula and all of the other established formulas, with no significant difference between median absolute error and mean absolute error. The Barrett True-K formula produced significantly more eyes within ±0.50 diopters than the SRK/T, Hoffer Q, and Holladay 1 formulas. [J Refract Surg. 2019;35(10):656-661.].

Evaluation of the relation between Lens Opacities Classification System III grading and nuclear size by direct measurement.

CONTEXT:Although relation between Lens Opacities Classification System III (LOCS III) and nuclear density is established, no data are available about nuclear size at different LOCS III grades.AIMS:The aim of this study is to evaluate the relation between LOCS III grading of nuclear opacity obtained preoperatively and the size of the nucleus obtained during cataract surgery.SETTINGS AND DESIGN:This was a prospective observational study carried out in a hospital attached to medical college.MATERIALS AND METHODS:Patients who underwent manual small-incision cataract surgery or extra-large temporal tunnel cataract extraction and gave consent were included in this study. Institutional Ethics Committee clearance was taken for the study. Preoperative LOCS III grading was obtained at slit-lamp biomicroscope. Ocular dimensions were obtained by preoperative immersion biometry. The thickness and diameter of the nucleus obtained by extraction were measured up to 10 μ accuracy. Data were analyzed for the change in nuclear thickness, nuclear diameter, age, lens thickness, and anterior chamber depth in relation to the LOCS III grade of the nucleus.STATISTICAL ANALYSIS USED:Statistical analysis used in this study was one-way ANOVA, mean, and range.RESULTS:There was a significant increase (P < 0.05) in nuclear thickness, nuclear diameter, and age with increasing LOCS III grade of the nucleus. The change in nuclear size was linear between Grades 1 and 4. The nuclear size did not increase between Grades 4 and 5. It increased steeply from Grade 5 to Grade 6.9.CONCLUSION:LOCS III grading of the nucleus can be utilized for determining the nuclear thickness and diameter preoperatively. These data can be helpful in adjusting machine parameters during phacoemulsification.

Prediction of Effective Lens Position Using Multiobjective Evolutionary Algorithm.

PurposeThe purpose of this study was to evaluate the prediction accuracy of effective lens position (ELP) after cataract surgery using a multiobjective evolutionary algorithm (MOEA).MethodsNinety-six eyes of 96 consecutive patients (aged 73.9 ± 8.6 years) who underwent cataract surgery were retrospectively studied; the eyes were randomly distributed to a prediction group (55 eyes) and a verification group (41 eyes). The procedure was repeated randomly 30 times to create 30 data sets for both groups. In the prediction group, based on the parameters of preoperative optical coherence tomography (OCT), biometry, and anterior segment (AS)-OCT, the prediction equation of ELP was created using MOEA and stepwise multiple regression analysis (SMR). Subsequently, the prediction accuracy of ELPs was evaluated and compared with conventional formulas, including SRK/T and the Haigis formula.ResultsThe rate of mean absolute prediction error of 0.3 mm or higher was significantly lower in MOEA (mean 4.9% ± 3.2%, maximum 9.8%) than SMR (mean 7.3% ± 4.8%, maximum 24.4%) (P = 0.0323). The median of the correlation coefficient (R2 = 0.771) between the MOEA predicted and measured ELP was higher than the SRK/T (R2 = 0.412) and Haigis (R2 = 0.438) formulas.ConclusionsThe study demonstrated that ELP prediction by MOEA was more accurate and was a method of less fluctuation than that of SMR and conventional formulas.Translational RelevanceMOEA is a promising method for solving clinical problems such as prediction of ocular biometry values by simultaneously optimizing several conditions for subjects affected by various complex factors.

Intraoperative aberrometry versus preoperative biometry for intraocular lens power selection in short eyes

To compare the accuracy of preoperative biometry-based formulas to intraoperative aberrometry (IA) with respect to predicting refractive outcomes after cataract surgery in short eyes. Private practice and community-based ambulatory surgery center. Retrospective consecutive case series. Eyes with an axial length (AL) shorter than 22.1mm underwent cataract extraction and intraocular lens (IOL) implantation. The predicted residual refractive error was calculated preoperatively using Hoffer Q, Holladay 2, Haigis, Barrett Universal II, and Hill-RBF formulas and intraoperatively using IA. The postoperative spherical equivalent (SE) was compared with the predicted SE to evaluate the accuracy of each aforementioned method. Fifty-one eyes from 38 patients met criteria to be included in the analysis. Without optimizing the formulas specifically for short eyes, the mean numerical errors (MNEs) associated with Hoffer Q, Holladay 2, Haigis, Barrett Universal II, Hill-RBF, and IA were -0.08 (95% confidence interval [CI], -0.30 to 0.13), -0.14 (95% CI, -0.35 to 0.07), +0.26 (95% CI, 0.05 to 0.47), +0.11 (95% CI, -0.10 to 0.32), +0.07 (95% CI, -0.14 to 0.28), and +0.00 (95% CI, -0.21 to 0.21), respectively (P<.001). The proportion of eyes within ±0.5 diopter (D) of the predicted SE were 49.0%, 43.1%, 52.9%, 52.9%, 60.8%, and 58.8%, respectively (P=.06). The prediction outcomes from IA were statistically better than Haigis, but not other formulas. When formula and IA predictions differed by 0.5 D or more, IA's ability to recommend a more emmetropic outcome was no better than chance (50%). Intraoperative aberrometry is not significantly different from the best preoperative biometry-based methods available for IOL power selection in short eyes.

Changes in Intraocular Pressure and Angle Status After Phacoemulsification in Primary Angle Closure Hypertension.

To study the change in intraocular pressure (IOP) and angle status after phacoemulsification in a cohort of primary angle closure hypertension (PACHT) patients. Tertiary Eye Care, India. Prospective interventional case-series. Case-series of 18 eyes of 18 patients. Preoperative biometry including axial length, anterior chamber depth (ACD), lens thickness, and central corneal thickness were studied. Preoperative and postoperative IOP, number of topical glaucoma medications, angle swept source optical coherence tomography (SS-OCT) parameters of nasal and temporal angle opening distance, trabecular iris space area, scleral spur angle, lens vault and circumferential iridotrabecular contact (ITC) were studied and their correlations derived. The mean preoperative IOP, 31±6 mm Hg, decreased to 14±1 mm Hg at 6-months postoperative period, P<0.001, a fall by 58±14%. The number of glaucoma medications reduced from 4(3-5) to 2(1-3), P<0.001. All SS-OCT studied parameters denoted significant angle widening postsurgery. The ITC% reduced from 52(16-100) to 19(0-97), P<0.001. The preoperative ITC showed moderate to strong correlation with all preoperative nasal and temporal angle parameters. It also showed moderate positive correlation with percentage fall in IOP at 1-month postoperative period. The preoperative ACD showed significant negative correlation with preoperative and postoperative ITC. PACHT patients benefit significantly from cataract surgery with marked angle widening, IOP reduction and a decrease in the number of glaucoma medications. The SS-OCT derived circumferential iridotrabecular contact index can be used as the single best parameter to indicate the preoperative angle status and predict postoperative change in IOP, as against the numerous single section measured angle parameters.

Ocular ultrasonographic evaluation of cataractous and pseudophakic eyes in dogs

Ocular B-mode ultrasonography is one of the noninvasive, rapid diagnostic imaging techniques indicated in canine cataract patients to evaluate the posterior segment of the eye. This study was conducted on twelve eyes of dogs with a history of cataract, which were scanned under topical anesthesia. The preoperative and postoperative ultrasonographic biometry, and ultrasonographic features of the lens, intraocular lens (IOL), and posterior segment were recorded. There was a significant difference between pre- and postphacoemulsification mean value of the axial length of globe and anterior chamber depth. The normal ultrasonographic features of the 2-hydroxy-ethyl-methylacrylate IOL was observed in vitro by placing the IOL in a coupling gel bath; it appeared as a flying saucer with hyperechoic margins and a central anechoic optic area and similar findings were also observed in pseudophakic eyes. Posterior segment changes such as posterior vitreous detachment were noticed in two dogs and retinal detachment in one dog postoperatively. In conclusion, ocular B-mode ultrasonography could be used to locate the position of the IOL in canine pseudophakic eyes. Ocular ultrasound is still more a useful tool to locate the position of the IOL postoperatively, even in pseudophakic eyes with corneal edema or iris synechiae in dogs.

Refractive outcomes of cataract surgery in primary congenital glaucoma.

To evaluate refractive outcomes of cataract surgery with intraocular lens (IOL) implantation in operated eyes of primary congenital glaucoma (PCG). A retrospective case-control study. Patients of PCG who developed cataract following trabeculectomy with trabeculotomy were recruited. Preoperative biometry was recorded and refractive outcomes of the patients in terms of spherical equivalent (SE) and prediction error were noted at 3 and at 12 months following surgery. The refractive outcomes were compared with non-glaucomatous eyes of children in similar age group who underwent lens aspiration with IOL implantation (controls). The median age of the children with PCG (n = 31) at the time of cataract surgery was 60 months, similar to controls (n = 29); 48 months (p = 0.3). The SE in PCG eyes at 12 months was comparable to controls (p = 0.18). The prediction error (postoperative SE - predicted SE) at 3 months (p = 0.018) and at 12 months (p = 0.03) among PCG eyes was higher and more myopic compared with controls. The range of prediction error at 12 months in PCG eyes was - 8.6 to + 5.8 D (median - 2.0 D), whereas in controls it was - 4.2 to + 6.3 D (median + 0.5 D). For each mmHg intraocular pressure (IOP) increase there was 0.42 mm increase in axial length among PCG eyes and a 0.24 mm increase among controls (p < 0.001). After IOL implantation there was a greater prediction error and a greater myopic shift among PCG eyes. Eyes of children with PCG are more prone to refractive surprises as their axial length changes are more sensitive to IOP fluctuation.

Preoperative biometry data of eyes with unilateral congenital cataract

To investigate the differences in biometry data of eyes with unilateral congenital cataract and the contralateral normal eyes in pediatric patients. Pediatric Ophthalmology Division, Ophthalmology Department, Semmelweis University in Budapest, Hungary. Retrospective case series. Data of visually significant unilateral congenital cataract patients who had cataract surgery in the ophthalmology department at Semmelweis University between 2013 and 2016 were collected. At the time of the examinations, the mean age of the patients was 36.4weeks±25.3 (SD). Central corneal thickness (CCT), corneal refractive power (keratometry [K]), horizontal corneal diameter, and axial length (AL) measurement data were obtained from both eyes of each patient. The measurements were taken under general anesthesia using a handheld kerato-refractometer (Retinomax K-plus 3) and an ultrasound instrument (Ocuscan RxP) with contact applanation method and Castroviejo straight-tip calipers at the beginning of the cataract surgery. For statistical evaluation, Originlab 7.0 software was used; paired t tests were performed for the difference analysis between the 2 sides. Forty-two infants (50% girls) were included. In the cases of eyes with unilateral congenital cataract, a greater CCT (P=.01330), higher average K (P=.00243), and smaller corneal diameter (P=.00010) were found, although there was no significant difference in AL when compared with the unaffected contralateral eyes. The data showed that biometric characteristics of the eyes with unilateral congenital cataract differ from the opposite normal eye before the cataract surgery. It is essential to use this biometric data in intraocular lens power calculation and to take them into account in long-term care when screening for secondary glaucoma.

Comparison of 9 modern intraocular lens power calculation formulas for a quadrifocal intraocular lens

To evaluate the accuracy of 9 formulas (Barrett Universal II, Haigis, Hill-Radial Basis Function [RBF], Hoffer Q, Holladay 1, Holladay 2, Olsen, Sanders-Retzlaff-Kraff/theoretical [SRK/T], and T2) calculating the power of the quadrifocal Acrysof IQ Panoptix TFNT00 intraocular lens (IOL). Department of Ophthalmology, Goethe University, Frankfurt, Germany. Retrospective case series. The study included patients having cataract surgery with insertion of a quadrifocal IOL over 15months. Preoperative biometry measurements were obtained from an IOLMaster 500. Optimized IOL constants were calculated to reduce the mean refractive prediction error. The primary outcomes were differences in mean absolute prediction error between the formulas. Median and maximum absolute prediction errors were evaluated as well as percentages of eyes within prediction errors of ±0.25 diopters (D), ±0.50 D, ±1.00 D, and ±2.00 D. The study comprised 75 eyes of 38 patients. The formulas were ranked by the mean absolute refractive prediction error as follows: Barrett Universal II (0.294 D), Hill-RBF (0.332 D), Olsen (0.339 D), T2 (0.351 D), Holladay 1 (0.381 D), Haigis (0.382 D), SRK/T (0.393 D), Holladay 2 (0.399 D), and Hoffer Q (0.410 D). The differences in absolute errors between the formulas were significant (P<.001). The lowest maximum absolute prediction error was obtained with the Barrett Universal II. The most accurate predictions of actual postoperative refraction were achieved using the Barrett Universal II, Hill-RBF, Olsen, or T2 formula. Thus, one of these formulas should be used for IOL power calculation of the quadrifocal IOL.

Accuracy of intraocular lens power calculation using three optical biometry measurement devices: the OA-2000, Lenstar-LS900 and IOLMaster-500.

To compare ocular measurements of three optical biometry devices and their application in intraocular lens (IOL) power calculations. One hundred and forty eyes which had undergone cataract extraction surgery with preoperative biometry with OA--2000, IOLMaster-500, and Lenstar-LS900 were enrolled. Biometry measurements of the three devices were compared. The deviation of the postoperative refraction from the preoperative refractive target was calculated with different formulas (Barrett Universal II, Hoffer Q, Holladay I, and SRK/T). Errors in the predicted astigmatism using the Barrett toric calculator were calculated for the toric IOLs. Additional 6465 eyes in which the IOLMaster-500 failed to measure axial length (AL) were reviewed. The percentage of successful measurements using the OA-2000 in those eyes was calculated. High agreement was found between the three devices for AL, anterior chamber depth, and average keratometry measurements (interclass correlation confidents: 1.000, 0.970, and 0.998, respectively, P < 0.001). The mean absolute prediction errors were similar using all formulas, ranging from 0.25 to 0.29 D, with no statistical significant difference between the three devices per each formula. The OA-2000 yielded a lower against-the-rule (ATR) centroid error in the predicted astigmatism than the IOLMaster-500 and Lenstar-LS900 (0.06 D ± 0.59 at 13.4° vs. 0.20 D ± 0.61 at 14.8° and 0.16 D ± 0.55 at 21.4°, respectively, P < 0.001, X-axis). Among 301 cases with unsuccessful AL readings using the IOLMaster-500, the OA-2000 had 284 (94.35%) successful measurements. The OA-2000 measurements showed good agreement with those of the IOLMaster-500 and Lenstar-LS900. Our results may suggest a potential advantage of the OA-2000 device in toric IOLs calculations and AL measurement success rate.

A model for predicting sulcus-to-sulcus diameter in posterior chamber phakic intraocular lens candidates: correlation between ocular biometric parameters.

The aim of this study was to determine the correlation between ocular biometric parameters and sulcus-to-sulcus (STS) diameter. This was a cross-sectional study of preoperative ocular biometry data of patients who were candidates for phakic intraocular lens (IOL) surgery. Subjects underwent ocular biometry analysis, including refraction error evaluation using an autorefractor and Orbscan topography for white-to-white (WTW) corneal diameter and measurement. Pentacam was used to perform WTW corneal diameter and measurements of minimum and maximum keratometry (K). Measurements of STS and angle-to-angle (ATA) were obtained using a 50-MHz B-mode ultrasound device. Anterior optical coherence tomography was performed for anterior chamber depth measurement. Pearson's correlation test and stepwise linear regression analysis were used to find a model to predict STS. Fifty-eight eyes of 58 patients were enrolled. Mean age±standard deviation of sample was 28.95±6.04years. The Pearson's correlation coefficient between STS with WTW, ATA, mean K was 0.383, 0.492, and -0.353, respectively, which was statistically significant (all P<0.001). Using stepwise linear regression analysis, there is a statistically significant association between STS with WTW (P=0.011) and mean K (P=0.025). The standardized coefficient was 0.323 and -0.284 for WTW and mean K, respectively. The stepwise linear regression analysis equation was: (STS=9.549+0.518 WTW-0.083 mean K). Based on our result, given the correlation of STS with WTW and mean K and potential of direct and essay measurement of WTW and mean K, it seems that current IOL sizing protocols could be estimating with WTW and mean K.

New algorithm for toric intraocular lens power calculation considering the posterior corneal astigmatism

To assess the accuracy of toric intraocular lens (IOL) power calculations of a new algorithm that incorporates the effect of posterior corneal astigmatism (PCA). Abbott Medical Optics, Inc., Groningen, the Netherlands. Retrospective case report. In eyes implanted with toric IOLs, the exact vergence formula of the Tecnis toric calculator was used to predict refractive astigmatism from preoperative biometry, surgeon-estimated surgically induced astigmatism (SIA), and implanted IOL power, with and without including the new PCA algorithm. For each calculation method, the error in predicted refractive astigmatism was calculated as the vector difference between the prediction and the actual refraction. Calculations were also made using postoperative keratometry (K) values to eliminate the potential effect of incorrect SIA estimates. The study comprised 274 eyes. The PCA algorithm significantly reduced the centroid error in predicted refractive astigmatism (P<.001). With the PCA algorithm, the centroid error reduced from 0.50 @ 1 to 0.19 @ 3 when using preoperative K values and from 0.30 @ 0 to 0.02 @ 84 when using postoperative K values. Patients who had anterior corneal against-the-rule, with-the-rule, and oblique astigmatism had improvement with the PCA algorithm. In addition, the PCA algorithm reduced the median absolute error in all groups (P<.001). The use of the new PCA algorithm decreased the error in the prediction of residual refractive astigmatism in eyes implanted with toric IOLs. Therefore, the new PCA algorithm, in combination with an exact vergence IOL power calculation formula, led to an increased predictability of toric IOL power.

Effect of fixation stability during biometry measurements on refractive prediction accuracy in highly myopic eyes

To assess the effect of preoperative biometry fixation stability on postoperative refractive errors in highly myopic cataractous eyes. Eye and ENT Hospital of Fudan University, Shanghai, China. Prospective cohort study. Eyes of highly myopic patients and emmetropic controls were included. Routine ophthalmologic examinations and measurement of fixation stability in the 63% and 95% bivariate contour ellipse areas (BCEAs) were conducted preoperatively. The refractive error from prediction was calculated 1month postoperatively with the SRK/T and Holladay 1 formulas. Univariate and multivariable analyses were performed to identify the factors associated with postoperative refractive errors. The refractive errors were more widely distributed inthe 45 highly myopic eyes than in the 40 emmetropic controleyes: SRK/T, +0.15 diopter [D]±0.80 [SD] and -0.16±0.35 D, respectively; Holladay 1, +0.54±0.79 D and -0.23±0.34 D, respectively. In the highly myopic group, 63% BCEA was correlated with axial length (AL) (P=.021) and posterior subcapsular opacity grade (P=.040). With both formulas, refractive errors and absolute refractive errors were positively correlated with 63% BCEA: SRK/T, P=.010 and P=.001, respectively; Holladay 1, P=.006 and P=.003, respectively. Backward multiple linear regression analysis showed that with both formulas, AL and 63% BCEA were significantly associated with postoperative refractive errors. Poor preoperative biometry fixation stability correlated with long AL and severe posterior subcapsular opacity contributed to significant deviation of refractive errors after cataract surgery in highly myopic eyes.

Intraoperative aberrometry versus preoperative biometry for intraocular lens power selection in axial myopia

To compare the accuracy of intraoperative wavefront aberrometry (ORA) and the Hill-radial basis function (RBF) formula with other formulas based on preoperative biometry in predicting residual refractive error after cataract surgery in eyes with axial myopia. Private practice, Harrisburg, Pennsylvania, USA. Retrospective consecutive case series. Eyes with an axial length (AL) greater than 25.0mm had cataract extraction with intraocular lens implantation. For each eye, the 1-center Wang-Koch AL-optimized Holladay 1formula was used to select an IOL targeting emmetropia. Residual refractive error was predicted preoperatively using theSRK/T, Holladay 1 and 2, Barrett Universal II, and Hill-RBF formulas and intraoperatively using wavefront aberrometry. The postoperative refraction was compared with the preoperative and intraoperative predictions. The study comprised 37 patients (51 eyes). The mean numerical errors ± standard error associated with using the SRK/T, Holladay 1, AL-optimized Holladay 1, Holladay 2, Barrett Universal II, and Hill-RBFformulas and intraoperative wavefront aberrometry were 0.20±0.06 diopters (D), 0.33±0.06 D, -0.02±0.06 D, 0.24±0.06 D, 0.19±0.06 D, 0.22±0.06 D, and 0.056±0.06D, respectively (P<.001). The proportion of patients within ±0.5 D of the predicted error was 74.5%, 62.8%, 82.4%, 79.1%, 73.9%, 76.7%, and 80.4%, respectively (P=.090). Hyperopic outcomes occurred in 70.6%, 76.5%, 49.0%, 74.4%, 76.1%, 74.4%, and 45.1% of the eyes, respectively (P=.007). Intraoperative wavefront aberrometry was better than all formulas based on preoperative biometry and as effective as the AL-optimized Holladay 1 formula in predicting residual refractive error and reducing hyperopic outcomes. The Hill-RBF formula's performance was similar to that of the fourth-generation formulas.

Circumferential silicone sponge scleral buckling induced axial length changes: case series and comparison to literature

BackgroundThis study compared axial length changes induced by circumferential scleral buckling using a silicone sponge with literature reports for solid silicone rubber.MethodsRecords of patients treated with scleral buckling in 2009–2013 using a silicone sponge, with preoperative axial length biometry measurements were reviewed. Additional information included age, type of surgery, additional surgeries, phakic status and anatomical success of reattachment. Patients underwent repeat biometry. The medical literature was reviewed for articles describing axial length changes induced by circumferential buckling using solid silicone rubber.ResultsTwenty-eight patients (mean age 49.7 years, range 16–72) met the inclusion criteria. Mean axial length was 25.38 mm preoperatively and 26.12 mm at least 6 months postoperatively (SD 0.50 ± 0.09, p < 0.001); a mean increase of 0.74 mm. Half the patients subsequently underwent cataract surgery. Post-operative changes were not significant compared to pre-surgical refraction and corneal astigmatism. Axial length change was not significant between sexes (9 women and 19 men).ConclusionsAxial length changes induced by circumferential scleral buckling using silicone sponge exclusively are similar to those reported in the literature for solid silicone rubber buckles. Scleral buckling using a silicone sponge, which may offer several surgical advantages, induces an acceptable axial length change similar to that seen with widely-used solid silicone rubber buckles.

The Comparative Study of Refractive Index Variations between Haigis, Srk/T and Hoffer-Q Formulas Used for Preoperative Biometry Calculation in Patients with the Axial Length >25 mm.

Background:To compare refractive index variation between Hoffer-Q, Haigis and SRK/T formulas used for preoperative biometry calculation in patients with axial length >25 mm, undergoing cataract surgery.Materials and Methods:This is a randomized clinical trial study was performed on 54 eyes of 54 patients with ages of 40–70 years old and axial length >25 mm classified into three groups that their IOL POWER were calculated by Haigis, SRK/T and Hoffer-Q formulas before undergoing cataract surgery. Their refractive index variations were calculated from the difference between predicted refractive error formula and actual post-operative refractive error formula. The collected data was entered in SPSS software and was analyzed by ANOVA and Chi-square statistical test.Results:With comparison sphere, astigmatism and spherical equivalent indexes before and after of cataract surgery between Haigis, SRK/T, and Hoffer-Q formulas, statistically significant differences were found between the mean of sphere and SE indexes in patients with use of Haigis and SRK/T formulas that have been more favorable post-operative refraction.Conclusions:Haigis formula and then, with slight difference, SRK/T formula have better and more acceptable post-operative refraction results than Hoffer-Q formula in patients with high axial myopia. Therefore, it is recommended using Haigis and SRK/T formulas for IOL power calculation in patients with high axial myopia undergoing cataract surgery.

Posterior Vault Distance of Ciliary Sulcus–Implanted Three-piece Intraocular Lenses According to Ciliary Sulcus Diameter

To investigate the correlation among preoperative biometry data, postoperative ciliary sulcus diameter, posterior vault distance, and effective lens position of ciliary sulcus-implanted intraocular lenses (IOLs). Retrospective interventional case series. Twenty-six eyes of 26 patients underwent phacoemulsification with implantation of a ZA9003 IOL (Abbott Medical Optics Inc, Santa Ana, California, USA) in the ciliary sulcus. We analyzed correlations among preoperative biometry data and ultrasound biomicroscopy measurements, ciliary sulcus diameter, posterior vault distance, and effective lens position. Regression analyses were performed to identify which combination of preoperative biometry data, average corneal power (keratometry [K]), anterior chamber depth (ACD), and axial length (AL) was best for predicting effective lens position. The sulcus diameter was shorter in eyes that had a steep cornea and shorter AL. The posterior vault distance was negatively correlated with sulcus diameter in subjects who had shorter postoperative time intervals (≤24months) (R2= 0.336 and P= .038). The posterior vault distance decreased with each passing postoperative month (R2= 0.158 and P= .045). The R2 value for predicting the effective lens positions of sulcus-implanted IOLs based on the entire average K, ACD, and AL was higher than those based on parts of these values. The effective lens position of sulcus-implanted IOLs can be affected by sulcus diameter, and lens position can change, especially in the early postoperative period. We recommend using the entire average K, ACD, and AL to predict the effective position of sulcus-implanted IOLs.

Pterygium size and effect on intraocular lens power calculation

To evaluate the effects of pterygium on biometry measurements and the relationship between these effects and pterygium size. Ulucanlar Eye Hospital, Ankara, Turkey. Prospective comparative study. Patients who had unilateral primary pterygium excision were included in the study group. Anterior segment photographed images were taken of eyes with pterygia to calculate the pterygium length and area using the ImageJ program. Preoperative and 3-month postoperative biometry measurements (Lenstar LS900) were obtained for eyes with pterygium and their healthy fellow eyes (control group). Thirty-two patients with pterygium (mean age 63.31years±7.18 [SD]) were included. The mean pterygium length was 3.07±0.81mm, and the mean area was 6.26±2.07mm2. The preoperative intraocular lens (IOL) power calculation with all formulas were higher than postoperative and control values (P<.001). The mean changes were 0.47 diopter (D) for the SRK II, 0.59 D for SRK/T, 0.47 D for Hoffer Q, 0.39 D for Haigis, and 0.38 D for Holladay 2 formulas after pterygium surgery. Positive, significant, and moderate correlations were found between the pterygium size and the change in IOL power. Pterygia longer than 2.40mm and larger than 5.45mm2 created at least equal to or more than 0.5D deviation in the IOL power calculations. If the pterygium size is larger than 2.40mm or 5.45mm2 and simultaneous surgery is planned, the implanted IOL power should be at least 0.50 D smaller than the calculated power. None of the authors has a financial or proprietary interest in any material or method mentioned.