Postoperative Refractive Error Research Articles

Intraocular lens power adjustment nomogram after laser in situ keratomileusis

To develop a nomogram for improving the accuracy of intraocular lens (IOL) power calculation at the time of cataract surgery based on the manifest refraction spherical equivalent (MRSE) change produced by laser in situ keratomileusis (LASIK). University-based clinical practice, Jules Stein Eye Institute, Los Angeles, California, USA. This was a retrospective review of the records of consecutive patients who had cataract surgery after LASIK. Spherical equivalent refractive data before and after LASIK and cataract surgery were recorded. The differences between the targeted postoperative refractive errors after cataract surgery and the achieved refractive errors were plotted against the LASIK-induced MRSE change, yielding postoperative refractive errors to target during IOL power calculation to achieve emmetropia. Thirty-two eyes of 23 patients were identified; 25 eyes had myopic LASIK and 7, hyperopic LASIK. Regression analysis yielded the following polynomial relationship: target postoperative refractive error (D) to achieve emmetropia during IOL power calculation = -0.018(MRSE Change)(2) + 0.192(MRSE Change) - 0.062. The outcomes in 97% of eyes fell within +/-1.00 D of the value predicted by this formula. A 2nd-order polynomial relationship was found between LASIK-induced MRSE change and the MRSE error after cataract surgery. From this equation, a simple adjustment nomogram was generated and put into a look-up table format. The formula and nomogram should improve IOL power calculation accuracy in post-LASIK eyes when the MRSE change is known.

Clinical Results of a Corneal Radius Correcting Factor in Calculating Intraocular Lens Power After Corneal Refractive Surgery

To describe the clinical results of a corneal radius correcting factor (CRCF), which is based on the axial length and independent of knowledge from the previous surgical procedure, in calculating intraocular lens (IOL) power in eyes that developed cataract after corneal refractive surgery. Intraocular lens power for 62 eyes that previously underwent corneal refractive surgery was calculated with the SRK/T and SRK II formulas using an axial length-related CRCF, and the expected refractive errors were compared with the actual postoperative refractive errors. Using the CRCF, the refractive outcomes ranged between -3.25 and +1.00 diopters (D) (mean -0.41+/-0.75 D), with 37 (60%) eyes within +/-0.50 D and 53 (85%) eyes within +/-1.00 D of the intended refraction. Using the raw data, without the correcting factor, the refractive outcomes would have ranged between -2.00 and +5.00 D (mean +2.17+/-1.45 D) with 7 (11%) eyes within +/-0.50 D and 15 (24%) eyes within +/- 1.00 D of the intended refraction. Pending further validation through a larger prospective evaluation, the CRCF combined with the SRK/T formula is recommended in eyes with an axial length up to 30 mm and the average IOL power calculated with the SRK/T and SRK II formulas when the axial length is >30 mm.

Intraoperative retinoscopy for intraocular lens power estimation in cases of combined phacoemulsification and silicone oil removal

To study the application of intraoperative retinoscopy for intraocular lens (IOL) power calculation in combined cataract extraction and silicone oil removal. Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India. This study comprised patients with silicone oil-filled eyes and visually significant cataract who had combined cataract extraction by phacoemulsification and silicone oil removal by a standard method through the pars plana route. Retinoscopy was performed with a streak retinoscope, standard vertex distance of 13.0 mm, and distance of 50.0 cm. All eyes had in-the-bag implantation of a foldable IOL with an A-constant of 118.4. The IOL power was calculated using the Ianchulev formula as follows: R x 2.01449. Postoperative refraction was performed at 3 months, and the spherical equivalent was calculated. Twelve eyes of 12 patients were evaluated. The mean emmetropic power calculated by intraoperative retinoscopy was 20.46 diopters (D) +/- 3.4 (SD) (range 13.09 to 25.18 D) and the mean refractive error, -0.45 +/- 0.63 D (range -1.00 to +1.00 D). The postoperative refractive error was within +/-0.50 D in 4 eyes (33.3%) and within +/-1.00 D in all eyes. Ten eyes (83.33%) had a postoperative refractive error in the range of 0.00 to -1.00 D using IOL power based on intraoperative retinoscopy. Intraoperative retinoscopy for IOL power calculation in combined cataract extraction and silicone oil removal gave satisfactory refractive outcomes, although further studies with more patients are required to confirm its usefulness and determine whether there are disadvantages.

Effects of measurement errors on refractive outcomes for pseudophakic eye based on eye model

With the Gullstrand–Le Grand eye model, the effects of various measurement errors on refractive outcomes for pseudophakic eye are studied. An equation to calculate the postoperative refractive error for pseudophakic eyes is derived. The accuracy to get a refractive error less than ca. 25 D is ±0.1 mm for the axial length, ±0.03 mm for the radius of the corneal anterior surface, ±0.12 D for the corneal power and ±0.16 mm for the postoperative anterior chamber depth (ACD). An error of 1 D in intraocular lens (IOL) power leads to a postoperative refractive error of −0.69 D. K-reading leads to a postoperative hyperopia from 0.18 to 0.74 D for eye with different refractive errors previously corrected. The constant velocity in ultrasound biometry assumption overestimates the axial length from 0.17 to 0.31 mm with actual axial length ranging from 21.31 to 32.31 mm. Errors in axial length, corneal power or radius of the corneal anterior surface and postoperative ACD play critical roles in determining the refractive outcomes. The constant-velocity assumption tends to overestimate the axial length. The change of the ratio of corneal anterior to the posterior surface is of minor importance for the overestimation of K-reading.

Clinical results in phacoemulsification using the SRK/T formula

To evaluate the prediction of refraction using the SRK/T formula for intraocular lens (IOL) calculation in eyes with medium axial length after phacoemulsification. This prospective study enrolled 33 eyes with nuclear cataract that underwent phacoemulsification. All procedures were performed by one surgeon with the intraocular lens placed within the capsular bag. The same technician who was unaware of the purpose of the study made all the measurements. The achieved refractive error one month after surgery was compared to the predicted postoperative refractive error by the SRK/T formula. The ocular axial length varied between 22.2 mm and 24.5 mm. The mean predicted refraction was -0.431 +/- 0.181 D and the mean achieved postoperative spherical equivalent was -0.220 +/- 0.732 D. Eighteen eyes (55%) had a refractive error between +/- 0.50 D and thirty eyes (91%) between +/- 1.00 D of the predicted refraction. There was a tendency toward hyperopic shift (mean +/- SD: 0.211 +/- 0.708 D, p=0.009). The SRK/T formula demonstrated a satisfactory accuracy to calculate the error of refraction in eyes with medium axial length.

Delayed in-the-bag implantation of intraocular lens

Objective: To report delayed in-the-bag intraocular lens (IOL) implantation for patients who had undergone simultaneous phacoemulsification and vitreoretinal surgery. Design: Interventional case series. Participants: Delayed IOL implantation surgery was performed for 3 patients who had undergone simultaneous phacoemulsification and scleral buckling or vitrectomy surgery. Methods: The medical records of each patient, including the surgical findings and final refraction status, were reviewed retrospectively. Results: Successful in-the-bag IOL implantation surgeries without capsular tear were achieved 3 to 5 months after the initial surgeries. The postoperative refractive error ranged from plano to −1.00 D. Conclusions: Successful in-the-bag IOL implantation and satisfactory refraction were achieved in patients who had undergone simultaneous phacoemulsification and scleral buckling or vitrectomy surgery.

Comparing Ultrasound Biometry with Partial Coherence Interferometry for Intraocular Lens Power Calculations: A Randomized Study

To determine whether intraocular lens (IOL) power calculations for cataract surgery as measured by postoperative refractive error using partial coherence interferometry (PCI) are more accurate in improving postoperative outcomes than applanation ultrasound biometry (AUS). A double-blind randomized controlled trial consisting of 205 patients was undertaken by the Southern Health Ophthalmology Unit, Victoria, Australia. Mean absolute postoperative refractive error (MAE) represented the dependent variable; the biometric technique (PCI; AUS) used to determine the IOL power to be implanted in the surgical eye represented the independent variable. An intention-to-treat analysis was used to prevent loss of randomization caused by the effects of crossover and drop-out. The MAE in patients with implanted PCI-calculated IOLs was 0.40 +/- 0.37 D (SD; 95% confidence interval [CI], 0.32-0.48 D) compared with 0.45 +/- 0.41 D (SD; 95% CI, 0.36-0.54 D) for patients with implanted AUS-calculated IOLs. There was no statistically significant difference between MAE in patients with implanted PCI-calculated IOLs and that in patients with AUS-calculated IOLs in analysis of best possible outcomes (t(167) = 1.0, P = 0.315). The results of this trial demonstrated that the calculation of IOL power based on ocular axial length measurement with PCI technology provided no clinical advantage over conventional applanation ultrasound, as measured by postoperative refractive outcome (anzctr.org.au number, ACTRN12608000077369).

Comparative Analysis of Contact and Immersion Technique in Ultrasonographic Biometry

Purpose: To establish the accuracy of the newly released biometer Ocuscan RxP (Alcon, USA) by comparison with the established Ultrasonic Biometer Model 820 (Allergan Humphrey, USA), and to compare the accuracy of contact and immersion biometries. Methods: This is a prospective study involving 27 patients (40 eyes) who were scheduled for cataract surgery and had axial lengths measured with an Ocuscan RxP biometer using both contact (Method 1) and immersion (Method 2) techniques. As a reference, a contact type Ultrasonic biometer 820 (Method 3) was also used. IOL(Intraocular Lens) power for the cataract surgery was calculated using this result. An axial length which would have caused no post-operative refractive error was reversely calculated from the difference of target diopter and post-operative refractive error. This length was compared with the axial lengths obtained via Methods 1, 2 and 3. Results: The means and standard deviations for the measurement sets were compared. Methods 1 and 2 showed no significant difference (23.220.68, 23.240.69 mm, p=0.55). The axial length measured by Method 3 was 23.320.67 mm. The difference between the target refraction and post-operative refractive error was 0.290.60D. The axial length was reversely calculated from the difference (23.070.84 mm). The differences between the reversely calculated axial lengths and those of Methods 1, 2 and 3 were 0.15 0.31, 0.170.31 and 0.240.28 mm, respectively. Conclusions: Biometric results from Methods 1 and 2 caused less refractive error than did Method 3. The contact and immersion methods are both accurate for IOL power calculation if performed by a well-skilled examiner.

Comparison of Formulas for Intraocular Lens Power Calculation Installed in a Partial Coherence Interferometer

Purpose: To evaluate the accuracy of various formulas installed in IOLMaster software which uses partial coherence interferometry for axial length measurement. Methods: This retrospective comparative study included 81 eyes of consecutive patients who had uneventful cataract surgery with implantation of Acrysof single piece (SA60AT) IOL. Axial length was measured with IOLMaster and IOL power was calculated using various formulas, including SRK II, SRK/T, Holladay 1, Haigis, and Hoffer Q. Subjects were stratified by axial length into Groups A (axial length axial length 25.00 mm). Target refractions of the five formulas were compared to the postoperative manifest refraction at 1 month. Results: The five formulas showed no difference in predicting postoperative refractive errors among all of the groups. Conclusions: Five formulas installed in IOLMaster software provided equivalent predictions of postoperative refractive error regardless of axial length.

COMPARISON OF REFRACTIVE OUTCOME USING INTRAOPERATIVE BIOMETRY AND PARTIAL COHERENCE INTERFEROMETRY IN SILICONE OIL-FILLED EYES

A-scan ultrasound is currently the most widely used technique for axial length measurement; however, this method is not optimal in silicone-oil filled eyes. Two techniques that may be more accurate for axial length measurements in these eyes are intraoperative measurement of axial length after silicone oil removal or measurement by Laser interferometry using the IOL Master. The purpose of this study is to evaluate and compare the accuracy of both intraoperative biometry and partial coherence interferometry in silicone oil-filled eyes. Axial length measurement of 22 cataractous silicone-filled eyes of 21 patients using both IOL Master Biometry and intraoperative A-scan biometry was performed. IOL power was then computed using the SRK-T formula. Accuracy of intraoperative biometry and partial coherence interferometry was evaluated by determining the mean actual postoperative refractive error. Comparing the predictability of intraoperative A-scan biometry and IOL Master Biometry, the two techniques showed small predictive postoperative refractive errors without a statistically significant difference in the predictive errors of the two techniques. Both intraoperative biometry by A-scan ultrasonography and partial coherence interferometer by IOL Master proved to have good equal predictability for absolute postoperative refractive error in cataract surgery for eyes filled with silicone oil.

Postoperative Refractive Error by Using A-scan in Cataract Surgery After Vitrectomy

Purpose: To investigate the difference between target refraction and actual refraction of intraocular lens implantation when cataract surgery was performed after vitrectomy. Methods: This study evaluated 28 eyes of 28 patients who had undergone vitrectomy without gas tamponade and 25 eyes of 25 patients who had undergone vitrectomy with gas tamponade. A-scans were performed before the respective cataract and vitrectomy surgeries. Three months after cataract surgery, the actual refraction was measured. To compare the difference between the actual and the target refraction calculated by each A-scan, the refractive prediction error was calculated. It is determined by subtracting the target refraction from the actual refraction. Results: In 28 eyes, the mean refractive prediction error calculated by the A-scan performed before vitrectomy was -0.146 0.901D (diopter, D), and the mean refractive prediction error calculated by an A-scan performed just prior to cataract surgery was -0.2281.011D. The two values were not statistically significant (p=0.653). In 25 eyes, the mean refractive prediction errors calculated by A-scans performed before vitrectomy and cataract surgery were -0.1711.079D, and -0.2270.798D, respectively. There was no statistically significant difference between the two values (p=0.563). Conclusions: When a cataract surgery was performed after vitrectomy, a precise target refraction could be obtained.

Clinical Result After Implantation of Minus Diopter Intraocular Lens in the High Myopia Patients

Purpose: To investigate the clinical results of 44 high myopic eyes with cataracts which had minus diopter IOLs (Intraocular lenses) implanted during cataract surgery. Methods: A retrospective chart review was done on 44 eyes in 33 patients who had undergone cataract extraction and minus diopter posterior chamber lens implantation. The IOL power was calculated using the SRK-T formula, and ACR6D SE (Corneal SA, France) IOL was implanted in all cases. We evaluated pre-operative target refraction, post-operative refraction at six months, pre-operative visual acuity with and without correction, and post-operative visual acuity with and without correction. The relationships between axial length and refractive error and between the diopter of IOLs and refractive error were analyzed. Results: The mean postoperative hyperopic refractive error compared to the preoperative target refraction was +1.04 1.05D, which was statistically significant (p

Excimer laser–assisted lamellar keratoplasty for the surgical treatment of keratoconus

To evaluate the anatomical and functional results of excimer laser-assisted lamellar keratoplasty (ELLK) in keratoconus patients. Eye Clinic, University of L'Aquila, L'Aquila, Italy. This prospective case series comprised patients with keratoconus who had ELLK and were examined preoperatively and 3, 6, 12, and 24 months postoperatively. Outcome measures were uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), refraction, computerized videokeratography, pachymetry, and endothelial specular microscopy. Forty-one eyes (41 patients) were examined. The UCVA and BSCVA were significantly better at all follow-up examinations than preoperatively. After the 24-month follow-up (33 patients), the UCVA was better than 20/60 in 11 patients (33.3%) and the BSCVA was 20/40 or better in 29 patients (87.9%). The mean refractive astigmatism was 2.20 diopters (D) and the mean manifest refraction spherical equivalent refraction, -1.18 D. Corneal topographic patterns were regularly astigmatic in 28 (84.8%) of 33 eyes, and the mean corneal thickness (440.0 mum) was significantly greater than preoperatively (553.0 mum). No statistically significant changes in mean corneal endothelial cell density were observed postoperatively. Complications included corneal melting treated with penetrating keratoplasty (PKP) (1 case) and postoperative high refractive error requiring topographically guided excimer laser photorefractive keratectomy (7 cases). Two-year findings indicate that ELLK is as efficacious as PKP for the surgical treatment of moderate to advanced keratoconus. The procedure is relatively simple. Most steps can be standardized, and there are no time-consuming maneuvers.

Optical biometry in combined phacovitrectomy

To assess the accuracy of intraocular lens (IOL) power calculation using optical biometry in patients having combined phacovitrectomy for macular hole and macular pucker. Sunderland Eye Infirmary, North East England, United Kingdom. This single-surgeon retrospective case series review comprised eyes having combined narrow-gauge phacovitrectomy for macular hole or macular pucker. Intraocular lens power was calculated using the results of optical biometry and the Haigis formula. Achieved and planned refraction were compared to calculate the mean postoperative refractive prediction error (ME) and the mean absolute postoperative prediction error (MAE) and the percentage of eyes with an achieved refraction within +/-0.50 diopter (D) and +/-1.00 D of the planned refraction. The results were compared with those in a series of 42 eyes that had phacoemulsification after previous vitrectomy surgery and a series of 60 nonvitrectomized eyes that had uneventful phacoemulsification. Of the of 59 having combined phacovitrectomy, 39 had macular hole and 20 had macular pucker. There was no statistically significant difference in refractive outcomes between the phacovitrectomy group (ME -0.02, MAE 0.39) and the sequential phacoemulsification group (ME -0.10, MAE 0.38) (P = .82). There was a statistically significant difference between the phacovitrectomy group and the phacoemulsification-only group (ME 0.08, MAE 0.26) (P<.001). The use of optical noncontact biometry with the Haigis formula achieved a high degree of accuracy of IOL power estimation in patients having phacovitrectomy. There was no tendency toward a myopic shift, as has been reported using ultrasound axial length measurement.

Relationship between preoperative aberrations and postoperative refractive error in enhancement of previous laser in situ keratomileusis with the LADARVision system

To identify factors leading to inaccuracy of spherical correction in wavefront-guided enhancement treatments. Department of Ophthalmology, University of California, Irvine, California, USA. This retrospective outcomes analysis comprised 23 eyes (20 patients) having wavefront-guided flap-lift (19 eyes) or photorefractive keratectomy (4 eyes) enhancements after conventional non-wavefront-guided laser in situ keratomileusis (LASIK) for correction of residual myopia with a minimum follow-up of 1 month. Main outcomes measures were changes in lower-order aberrations and higher-order aberrations (HOAs) related to predictability of the refractive outcome. The enhancement procedures reduced HOAs. Because of a hyperopic shift, however, uncorrected visual acuity (UCVA) improved 2 or more Snellen lines in 3 of 9 eyes (33.3%) treated without a surgeon offset compared with 9 of 14 (64.3%) when a surgeon offset was incorporated into the treatment plan. The quantitative amount of preoperative HOAs correlated with the amount of hyperopic shift, particularly strongly for spherical aberration (r(2) = 0.446, P = .0005). The amount of hyperopic shift was related in a linear manner to the amount of HOAs (for spherical aberrations, Y = 1.31X - 0.30, where Y is the postoperative manifest refraction spherical equivalent and X is the wavefront error in microns root mean square). Wavefront-guided enhancements can reduce levels of HOAs. Although UCVA improved in many patients, some with high levels of preenhancement spherical aberration had worse UCVA. Adjusting the nomogram for the amount of preenhancement HOAs may improve the accuracy of the lower-order correction in wavefront-guided enhancements.

Comparison of Clinical Results between Heparin Surface Modified Hydrophilic Acrylic and Hydrophobic Acrylic Intraocular Lens

To compare the clinical results of heparin surface modified (HSM) hydrophilic acrylic intraocular lens (IOL) with those of hydrophobic acrylic IOL. One hundred patients with cataract were randomized to receive one of acrylic foldable IOLs after phacoemulsification: HSM hydrophilic acrylic IOL (n=50) BioVue3 (BioVue, OII, Ontario, CA, USA) and hydrophobic acrylic IOL (n=50) Sensar (AR40e, AMO, Santa Ana, CA, USA). Bestcorrected visual acuity and refractive error were measured at 1 week, 2 months, 6 months and 12 months after surgery in both IOL groups. To assess posterior capsular opacification (PCO), digital retroillumination image of posterior capsule was analyzed at 12 months using POCOman software. Best-corrected visual acuity (log MAR) was 0.032+/-0.082 in BioVue3 group and 0.034+/-0.077 in Sensar group at 12 months. There was no statistically significant difference between the two groups (p=0.554). Refractive error was -0.247+/-0.821 diopter in BioVue3 group and -0.264+/-0.808 diopter in Sensar group at 12 months. There was no statistically significant difference of refractive error between the two groups (p=0.909). At 12 months, BioVue3 IOL group had a lower percentage area and severity of PCO than Sensar group. However, it was not statistically significant (p=0.349, p=0.288). No Nd:YAG capsulotomy was performed in BioVue3 group while it was required in two eyes (4.0%) in Sensar group. There was no statistically significant difference of postoperative visual acuity, refractive error and degree of PCO between HSM hydrophilic acrylic IOL and hydrophobic acrylic IOL.

CATARACT SURGERY;

Objectives: To describe the variation of axial length in patients undergoingcataract surgery. Study design: A retrospective case series. Place and duration of study: At OpthalmologicalDepartment, Allied Hospital, PMC, Faisalabad from May 2006 to June 2007. Patients and methods: The axial lengthof 566 patients who were admitted for cataract surgery were measured with A. scan (Axis II, Quantel). The elevenpatients with age below 15 years and above 90 years and with history of trauma, corneal scarring were excluded. Sothere were 555 patients for this study. A careful history of diabetes mellitus, hypertension, trauma, previous history ofsurgery, glaucoma and uveitis was taken, and slit lamp examination, tonometry, pupillary reactions, perception andprojection of light was done. The data collected was entered in specially designed Performa. An average of tenreadings of axial lengths with A-Scan for each patient was taken. Results: Out of 555 patients, there were 350 male(63.06%) and 205 female (36.94%) patients. There were 250(45.05%) patients having age between 46 to 60 years.There were 27(4.86%) patients having age between 15 to 30 years and the same number 27(4.86%) of patients wasseem having age between 76 to 90 years. The most of the patients 273(49.18%) had axial length between 23mm to25 mm. There were only 3 patients with axial length between 29.01 to 31 mm. There were a significant number ofpatients, 230(41.45%) having axial length between 21.01 to 23mm. Conclusion: The biometry depends upon axiallength, kratometry and anterior chamber depth. Most of the formulae supposed for IOL calculations depend upon onlytwo factors, the axial length and the keratometry. In our community, short and long eyes are very rare and so SRK-Tformula for IOL calculations provides satisfactory postoperative results. The axial length carries more importance asits variation causes a gross change in IOL power and postoperative refractive errors.

Biometric calculation of intraocular lens power for cataract surgery following pupil dilatation

The ability to perform biometry accurately on a dilated pupil can greatly facilitate the efficiency of a cataract service as it can be done on the day of surgery. The purpose of this study was to assess the repeatability of axial length (AL) calculations in undilated pupils and measure the difference in predicted and actual refractive outcomes in dilated pupils compared with undilated pupils. First, intraobserver repeatability was assessed by taking two consecutive recordings of AL using applanation A-scan ultrasonography in undilated pupils in 21 eyes. The mean AL for each eye was compared with a measurement made following pupil dilatation. Second, we audited the mean spherical equivalent refractive errors following routine cataract surgery in 38 patients with undilated pupils and 36 patients with dilated pupils. The mean difference in intraobserver measurements was -0.05 mm (standard deviation [SD] 0.15) with pupils undilated. Following pupil dilatation, the mean dilated AL differed from the mean undilated AL reading by only 0.03 mm (P > 0.05). The mean differences between planned and actual refractive error were 0.71D (SD 0.54) and 0.55D (SD 0.41) in dilated and undilated patients, respectively. This was not statistically significant (P > 0.05). The range of differences between target and actual refraction was -1.45D to 2.70D for undilated patients and -1.88D to 1.18D in dilated patients. Although there was a greater spread of postoperative refractive errors in the dilated group, there were no statistically or clinically significant differences in postoperative refractive errors between the two categories of patients. Our study shows that applanation biometry may be safely performed for the purpose of cataract surgery after pupil dilatation.

Prediction of Refractive Error in Combined Vitrectomy and Cataract Surgery With One-Piece Acrylic Intraocular Lens

PurposeTo compare the predicted and actual refractive errors of hydrophilic, one-piece, C-flex®570C (C-flex) intraocular lens (IOL) implantation in simultaneous vitrectomy and lens extraction in various conditions.MethodsOne hundred fifty-nine eyes of patients who had lens extraction between March 2004 and September 2005 were enrolled in a retrospective study. Group 1 had lens extraction and IOL implantation, and Group 2 had lens extraction and IOL implantation with vitrectomy. IOL calculation was done with axial length and keratometry measurements. The actual and predicted refractive errors were compared at 1 and 6 months postoperatively. The factors influencing the postoperative refractive outcomes were analyzed.ResultsThe mean refractive predictive error (i.e., the actual minus predicted spherical equivalent) was +0.19±0.39 D (Diopter) and -0.26±0.45 D at 1 and 6 months postoperatively (all: p<0.001) in group 1, and -0.22±0.39 D and -0.06±0.62 D at 1 and 6 months postoperatively (p=0.013, p=0.399 respectively). In group 2, all surgical factors related to refractive errors were not statistically significant (all: p>0.05).ConclusionsRefractive errors in combined surgery showed myopic shift of -0.50 D and -0.32 D at 1 and 6 months postoperatively compared with C-flex IOL implantation alone. With the hyperopic tendency of IOL and myopic tendency of vitrectomy, the combined surgery made postoperative refractive errors near emmetropia.

A long-term follow-up study of different irrigation/aspiration techniques on formation of posterior capsule opacification

Background: This study was designed to determine the effect of 2 different irrigation/aspiration techniques on the formation of posterior capsule opacification (PCO) after cataract surgery in which CeeON Edge 911A (Pharmacia, Sweden) sharp-edged silicone lenses were implanted. Methods: In this prospective study, 60 eyes from 39 patients, average age 65 (range: 46–85) years, were analyzed. Lens extraction was performed by phacoemulsification, and CeeON Edge 911A intraocular lenses were implanted. Two different irrigation/aspiration techniques were used in which the cortex of 32 eyes was removed by coaxial irrigation/aspiration (this group was designated group I) and the cortex of 28 eyes was removed by bimanual irrigation/aspiration (this group was designated group II). Secondary cataract formation and visual acuity were evaluated and compared in both groups. Results: The average follow-up time was 44 (SD 11) months. In group I, secondary cataract formation causing 2 lines of decrease on visual acuity was observed in 1 eye 8 months after the operation. The secondary cataract developed in the form of cortex migration. This patient was treated with laser (Neodymium: Yttrium Aluminum Garnet [Carl Zeiss Meditech, Germany]) capsulotomy at the time of detection. Best corrected visual acuity for all eyes was 0.5 and higher; postoperative refractive error ranged between +1.0 and −2.0 diopters. Interpretation: Although CeeON Edge 911A silicone lenses with sharp edge prevent formation of PCO very effectively, in 1 eye in the coaxial irrigation/aspiration group, 2 lines of decrease on visual acuity were observed due to PCO. However, we did not find any significant difference between the 2 irrigation/aspiration techniques with respect to PCO formation. In terms of complete removal of the cortical material, the bimanual irrigation/aspiration technique was found to be superior to the coaxial irrigation/aspiration technique because of the better accessibility to all areas of the capsular bag.