Positional accommodative intraocular lens power error induced by the estimation of the corneal power and the effective lens position

Purpose:

To evaluate the predictability of the refractive correction achieved with a positional accommodating intraocular lenses (IOL) and to develop a potential optimization of it by minimizing the error associated with the keratometric estimation of the corneal power and by developing a predictive formula for the effective lens position (ELP).

Materials and Methods:

Clinical data from 25 eyes of 14 patients (age range, 52–77 years) and undergoing cataract surgery with implantation of the accommodating IOL Crystalens HD (Bausch and Lomb) were retrospectively reviewed. In all cases, the calculation of an adjusted IOL power (P_IOLadj) based on Gaussian optics considering the residual refractive error was done using a variable keratometric index value (n_kadj) for corneal power estimation with and without using an estimation algorithm for ELP obtained by multiple regression analysis (ELP_adj). P_IOLadj was compared to the real IOL power implanted (P_IOLReal, calculated with the SRK-T formula) and also to the values estimated by the Haigis, HofferQ, and Holladay I formulas.

Results:

No statistically significant differences were found between P_IOLReal and P_IOLadj when ELP_adj was used (P = 0.10), with a range of agreement between calculations of 1.23 D. In contrast, P_IOLReal was significantly higher when compared to P_IOLadj without using ELP_adj and also compared to the values estimated by the other formulas.

Conclusions:

Predictable refractive outcomes can be obtained with the accommodating IOL Crystalens HD using a variable keratometric index for corneal power estimation and by estimating ELP with an algorithm dependent on anatomical factors and age.     

In-the-bag scleral suturing of intraocular lens in eyes with severe zonular dehiscence

Purpose

To compare the degree of tilt and decentration of an intraocular lens (IOL), refractive status, and prediction error between eyes that underwent trans-scleral suturing of the IOL within the capsular bag (in-the-bag scleral suturing) and eyes that underwent scleral suturing outside of the bag (out-of-the-bag scleral suturing) because of severe zonular dehiscence.

Patients and methods

Thirty eyes that underwent in-the-bag scleral suturing of an IOL and 38 eyes that underwent out-of-the-bag scleral suturing were recruited sequentially. The tilt and decentration of the IOL, anterior chamber depth, manifest refractive spherical equivalent (MRSE), prediction error, and incidence of complications were examined.

Results

The mean tilt angle and the decentration length of the IOL of the in-the-bag suturing group were significantly less than those of the out-of-the-bag suturing group (P=0.0003 in tilt and P=0.0391 in decentration), although the anterior chamber depth was similar. The mean MRSE and prediction error of the in-the-bag suturing group were less than those of the out-of-the-bag suturing group (P=0.0006 in MRSE and P=0.0034 in error). The incidence of vitreous loss was less in the in-the-bag suturing group than in the out-of-the-bag suturing group (20% vs63.2%, P=0.0009).

Conclusions

The tilt and decentration of the IOL after in-the-bag scleral suturing are significantly less than those after out-of-the-bag scleral suturing, which may lead to less MRSE and less prediction error. As the incidence of vitreous loss is less after in-the-bag scleral suturing, in-the-bag suturing is advantageous for eyes of younger patients and of less complicated cases.     

Long-Term Efficacy and Rotational Stability of AcrySof Toric Intraocular Lens Implantation in Cataract Surgery

Purpose

To evaluate the long-term efficacy and rotational stability of the AcrySof toric intraocular lens (IOL) in correcting preoperative astigmatism in cataract patients.

Methods

This prospective observational study included 30 eyes from 24 consecutive patients who underwent implantation of an AcrySof toric IOL with micro-coaxial cataract surgery between May 2008 and September 2008. Outcomes of visual acuity, refractive and keratometric astigmatism, and IOL rotation after 1 day, 1 month, 3 months, and long-term (mean, 13.3±5.0 months) follow-up were evaluated.

Results

At final follow-up, 73.3% of eyes showed an uncorrected visual acuity of 20/25 or better. The postoperative keratometric value was not different from the preoperative value; mean refractive astigmatism was reduced to -0.28±0.38 diopter (D) from -1.28±0.48 D. The mean rotation of the toric IOL was 3.45±3.39 degrees at final follow-up. One eye (3.3%) exhibited IOL rotation of 10.3 degrees, the remaining eyes (96.7%) had IOL rotation of less than 10 degrees.

Conclusions

Early postoperative and long-term follow-up showed that implantation of the AcrySof toric IOL is an effective, safe, and predictable method for managing corneal astigmatism in cataract patients.     

Comparative analysis of the visual and refractive outcomes of a refractive segmented multifocal intraocular lens with and without toricity: 1-year results

Purpose

To compare the visual and refractive outcomes up to 1 year postoperatively following implantation of a refractive segmented or a refractive segmented toric multifocal intraocular lens (IOL).

Methods

This retrospective study included 108 eyes of 64 patients who underwent cataract surgery with implantation of a refractive segmented multifocal IOL (Lentis Mplus LS-313 MF30 IOL) (LM group) and 81 eyes of 49 patients with implantation of a refractive segmented toric multifocal IOL (Lentis Mplus LU-313 MF30T IOL) (LMT group). The visual and refractive postoperative outcomes and the rate of additional refractive procedures were evaluated up to 1 year postoperatively.

Results

The uncorrected distance visual acuity (VA) and uncorrected near VA exceeded 1.0 and 0.60 in decimal VA, respectively, and both were stable postoperative groups. The postoperative subjective refractive astigmatism was also stable and the postoperative refraction was near emmetropia in both groups. No significant differences were found in the need for additional surgical refractive procedures.

Conclusion

The outcomes with a refractive segmented toric multifocal IOL were comparable to those with a non-toric model despite higher preoperative corneal astigmatism.

     

Meta‐analysis of accuracy of intraocular lens power calculation formulas in short eyes

Importance

Intraocular lens (IOL) power selection is a critical factor affecting visual outcome after IOL implantation in short eyes. Many formulas have been developed to achieve a precise prediction of the IOL power. However, controversy regarding the accuracy remains.

Background

To investigate the accuracy of different IOL power calculation formulas in short eyes.

Design

Meta‐analysis.

Participants

Patients with the axial length of eyes less than 22 mm from previously reported studies.

Methods

A comprehensive search in Pubmed, EMBASE, Cochrane Data Base of Systematic Reviews and the Cochrane Central Register of Controlled Trials was conducted by October 2016. We assessed the methodological quality using a modified QUADAS‐2 tool and performed analysis on weighted mean differences of mean absolute errors (MAE) among different formulas.

Main Outcomes Measures

The between‐group difference of MAE was evaluated with weighted mean difference and 95% confidence intervals.

Results

Ten observational studies, involving 1161 eyes, were enrolled to compare six formulas: Haigis, Holladay 2, Hoffer Q, Holladay 1, SRK/T and SRK II. Among them, the Holladay 2 introduced the smallest overall MAE (0.496D) without statistical significance. The difference of MAE is statistically significant between Haigis and Hoffer Q (mean difference = ?0.07D, P = 0.003), Haigis and SRK/T (mean difference = ?0.07D, P = 0.009), Haigis and SRK II (mean difference = ?0.41D, P = 0.01). For publication bias and small‐study effect, neither funnel plot nor egger's test detected statistical finding.

Conclusion and Relevance

The overall evidence from the studies confirmed the superiority of Haigis over Hoffer Q, SRK/T and SRK II in prediction IOL power in short eyes.

     

Accuracy of intraocular lens power calculation formulas in long eyes: a systematic review and meta‐analysis

Importance

Visual outcome after intraocular lens (IOL) implantation in long eyes is considerably affected by IOL power calculation. Various formulas have been designed to achieve an accurate IOL power prediction. However, controversy about the accuracy remains.

Background

To evaluate the accuracy of IOL power calculation formulas in long eyes.

Design

Meta‐analysis.

Participants

Patients with ocular axial length (AL) over 24.5 mm.

Methods

A comprehensive search in PubMed, EMBASE, Cochrane Data Base of Systematic Reviews and the Cochrane Central Register of Controlled Trials were conducted by September, 2017. The weighted mean differences of mean absolute errors (MAE) and the odds ratio of percentage of eyes within ±0.50D of prediction error among formulas were analysed.

Main Outcomes Measures

Between‐group differences of MAE among formulas.

Results

Eleven observational studies, involving 4047 eyes, were enrolled. Six formulas for IOL power calculation were compared: Barrett Universal II, Haigis, Holladay 2, SRK/T, Hoffer Q and Holladay 1. The MAE of Barrett Universal II was statistically lower than that of Holladay 2 (mean difference, MD = ?0.04D, P = 0.0002), SRK/T (MD = ?0.05D, P < 0.00001), Hoffer Q (MD = ?0.07D, P < 0.00001) and Holladay 1 (MD = ?0.07D, P < 0.00001). Barrett Universal II yielded significantly higher percentage of eyes within ±0.50D of the prediction error than the other formulas. The heterogeneity was minimized through dividing eyes into two groups by the AL of 26 mm.

Conclusions and Relevance

This study demonstrates the superiority of Barrett Universal II over Holladay 2, SRK/T, Hoffer Q and Holladay 1 in predicting IOL power in long eyes.

     

Contrast visual acuity after multifocal intraocular lens implantation:aspheric versus spherical design

AIM: To evaluate contrast visual acuity (CVA) after implantation of an aspheric apodized diffractive intraocular lens (IOL) or a spherical apodized diffractive IOL in cataract surgery. METHOD: This prospective randomized controlled study with a 12-month follow-up compared the results of cataract surgery with implantation of an aspheric AcrySof ReSTOR SN6AD3 IOL (30 eyes) and a spherical AcrySof ReSTOR SN60D3 IOL (30 eyes). CVA with best distance correction was measured at 4 contrast levels (100%, 25%, 10% and 5%) under 3 levels of chart luminance [250, 85 and 25 candelas per square meter (cd/m²)] using a multi-functional visual acuity tester (MFVA-100)． RESULTS:At 12 months after surgery, there were no statistically significant differences in 100% CVA and 25% CVA under 250cd/m² (P100%=0.875 and P25%=0.057) and 85cd/m² (P100%=0.198 and P25%=0.193) between the aspheric group and the spherical group. However, the 10% CVA and 5% CVA were significant better in aspheric group than spherical group under 250cd/m² (P10%=0.042 and P5%=0.007) and 85cd/m² (P10%=0.002 and P5%=0.039). Under the luminance level of 25cd/m², no significant differences was found in the 100% CVA between the 2 group (P100%=0.245), while aspheric group had better visual acuity in the remaining 3 contracts (P25%=0.023, P10%=0.026 and P5%=0.002, respectively). CONCULSION:The aspheric AcrySof ReSTOR SN6AD3 IOL provided patients with better low-contrast visual acuity than the spherical AcrySof ReSTOR SN60D3 IOL.     

The refractive outcome of Toric Lentis Mplus implant in cataract surgery

AIM: To evaluate the refractive outcome of Toric Lentis Mplus intraocular lens (IOL) implant. METHODS: This is a retrospective case series. Consecutive patients with corneal astigmatism of at least 1.5 D had Toric Lentis Mplus IOL implant during cataract surgery. The exclusion criteria included irregular astigmatism on corneal topography, large scotopic pupil diameter (>6 mm), poor visual potential and significant ocular comorbidity. Postoperative manifest refraction, uncorrected distance visual acuity (UDVA), best-corrected distance visual acuity (BCVA), uncorrected intermediate visual acuity (UIVA) at 3/4 m and uncorrected near visual acuity (UNVA) were obtained. RESULTS: There were 70 eyes from 49 patients in this study. Patients were refracted at a median of 8.9wk (range 4.0 to 15.5) from the operation date. Sixty-five percent of eyes had 6/7.5 (0.10 logMAR) or better, and 99% 6/12 (0.30 logMAR) or better postoperative UDVA. Eighty-nine percent could read Jaeger (J) 3 (0.28 logMAR) and 95% J5 (0.37 logMAR) at 40 cm. The median magnitude of astigmatism decreased from 1.91 D to 0.49 D (Wilcoxon, P<0.001) after the operation. The range of the cylindrical error was reduced from 1.5-3.95 D (keratometric) preoperatively to 0.00-1.46 D (subjective refraction transposed to corneal plane) postoperatively. CONCLUSION: Toric Lentis Mplus IOL has good predictability in reducing preexisting corneal astigmatism.     

Estimation of Intraocular Lens Power Calculation after Myopic Corneal Refractive Surgery: Using Corneal Height in Anterior Segment Optical Coherence Tomography

PurposeTo investigate the feasibility of estimating effective lens position (ELP) and calculating intraocular lens power using corneal height (CH), as measured using anterior segment optical coherence tomography (AS-OCT), in patients who have undergone corneal refractive surgery.MethodsThis study included 23 patients (30 eyes) who have undergone myopic corneal refractive surgery and subsequent successful cataract surgery. The CH was measured with AS-OCT, and the measured ELP (ELP_m) was calculated. Intraocular lens power, which could achieve actual emmetropia (P_real), was determined with medical records. Estimated ELP (ELP_est) was back-calculated using P_real, axial length, and keratometric value through the SRK/T formula. After searching the best-fit regression formula between ELP_m and ELP_est, converted ELP and intraocular lens power (ELP_conv, P_conv) were obtained and then compared to ELP_est and P_real, respectively. The proportion of eyes within a defined error was investigated.ResultsMean CH, ELP_est, and ELP_m were 3.71 ± 0.23, 7.74 ± 1.09, 5.78 ± 0.26 mm, respectively. The ELP_m and ELP_est were linearly correlated (ELP_est = 1.841 × ELP_m - 2.018, p = 0.023, R = 0.410) and ELP_conv and P_conv agreed well with ELP_est and P_real, respectively. Eyes within ±0.5, ±1.0, ±1.5, and ±2.0 diopters of the calculated P_conv, were 23.3%, 66.6%, 83.3%, and 100.0%, respectively.ConclusionsIntraocular lens power calculation using CH measured with AS-OCT shows comparable accuracy to several conventional methods in eyes following corneal refractive surgery.     

Refractive Changes after Removal of Anterior IOLs in Temporary Piggyback IOL Implantation for Congenital Cataracts

Purpose

To assess the refractive change and prediction error after temporary intraocular lens (IOL) removal in temporary polypseudophakic eyes using IOL power calculation formulas and Gills'' formula.

Methods

Four consecutive patients (7 eyes) who underwent temporary IOL explantation were enrolled. Postoperative refractions calculated using IOL power calculation formulas (SRK-II, SRK-T, Hoffer-Q, Holladay, and the modified Gills'' formula for residual myopia and residual hyperopia) were compared to the manifest spherical equivalents checked at 1 month postoperatively.

Results

The mean ages of temporary piggyback IOL implantation and IOL removal were 6.71 ± 3.68 months (range, 3 to 12 months) and 51.14 ± 18.38 months (range, 29 to 74 months), respectively. The average refractive error was -13.11 ± 3.10 diopters (D) just before IOL removal, and improved to -1.99 ± 1.04 D after surgery. SRK-T showed the best prediction error of 1.17 ± 1.00 D. The modified Gills'' formula for myopia yielded a relatively good result of 1.47 ± 1.27 D, with only the variable being axial length.

Conclusions

Formulas to predict refractive change after temporary IOL removal in pediatric polypseudophakia were not as accurate as those used for single IOL implantation in adult eyes. Nonetheless, this study will be helpful in predicting postoperative refraction after temporary IOL removal.     

Combined 23-gauge microincisonal vitrectomy surgery and phacoemulsification with AcrySof toric intraocular lens implantation: a comparative study

Aim

To compare AcrySof toric intraocular lens (IOL) and non-toric IOL in patients who had combined 23-gauge microincisional vitrectomy surgery (MIVS) and phacoemulsification for vitreoretinal diseases and cataract with pre-existing corneal astigmatism.

Methods

This is a prospective comparative study comprised of 30 patients (30 eyes) who had combined 23-gauge MIVS and phacoemulsification for vitreoretinal diseases and cataract with pre-existing regular corneal astigmatism greater than 1 diopters (D). In all, 15 eyes had AcrySof toric IOL (Alcon Laboratories) and 15 eyes had non-toric IOL (Akreos AO MI60; Bausch & Lomb) implantation. Main outcome measures were uncorrected visual acuity (UCVA), refractive cylinder, surgically induced astigmatism (SIA), and IOL misalignment during 6 months.

Results

The mean UCVA of the toric IOL group was better than the non-toric IOL group at postoperative months 1, 3, and 6 (P<0.001, respectively). The mean absolute residual refractive cylinder of the toric IOL group at postoperative week 1, and months 1, 3, and 6 was less than the non-toric IOL group (P=0.008, <0.001, <0.001, and <0.001, respectively). There was no difference in the mean SIA between the two groups (P>0.05, respectively). The mean toric IOL axis rotation was 3.52±2.75°, which was within 5° in 66.7% of the toric IOL group and within 10° in 100%.

Conclusions

Combined 23-gauge MIVS and phacoemulsification with AcrySof toric IOL implantation is an effective method of correcting vitreoretinal diseases and cataract and pre-existing corneal astigmatism, and the toric IOL showed good rotational stability, even in vitrectomized eyes for 6 months.     

Intraocular lens power calculation using IOLMaster and various formulas in short eyes

Purpose

To evaluate the predictability of intraocular lens (IOL) power calculations using the IOLMaster and four different IOL power calculation formulas (Haigis, Hoffer Q, SRK II, and SRK/T) for cataract surgery in eyes with a short axial length (AL).

Methods

The present study was a retrospective comparative analysis which included 25 eyes with an AL shorter than 22.0 mm that underwent uneventful phacoemulsification with IOL implantation from July 2007 to December 2008 at Seoul National University Boramae Hospital. Preoperative AL and keratometric power were measured by the IOLMaster, and power of the implanted IOL was determined using Haigis, Hoffer Q, SRK II, and SRK/T formulas. Postoperative refractive errors two months after surgery were measured using automatic refracto-keratometry (Nidek) and were compared with the predicted postoperative power. The mean absolute error (MAE) was defined as the average of the absolute value of the difference between actual and predicted spherical equivalences of postoperative refractive error.

Results

The MAE was smallest with the Haigis formula (0.37 ± 0.26 diopter [D]), followed by those of SRK/T (0.53 ± 0.25 D), SRK II (0.56 ± 0.20 D), and Hoffer Q (0.62 ± 0.16 D) in 25 eyes with an AL shorter than 22.0 mm. The proportion with an absolute error (AE) of less than 1 D was greatest in the Haigis formula (96%), followed by those in the SRK II (88%), SRK-T (84%), and Hoffer Q (80%).

Conclusions

The MAE was less than 0.7 D and the proportion of AE less than 1 D was more than 80% in all formulas. The IOL power calculation using the Haigis formula showed the best results for postoperative power prediction in short eyes.     

Trocar-assisted sutureless intrascleral posterior chamber foldable intra-ocular lens fixation

Purpose

We report a novel technique characterized by sutureless scleral fixation of three-pieces foldable intraocular lens (IOL) using 25-gauge transconjunctival sutureless vitrectomy (TSV) trocars in patients with insufficient posterior capsule support.

Materials and Methods

We performed this technique on the eight eyes of the seven patients. The scleral tunnels (STs) are prepared by insertion of the 25-gauge TSV microcannulas using the trocars, and anterior vitrectomy is performed through the clear corneal paracentesis with the aid of anterior chamber maintainer (ACM). Finally, the three-piece foldable IOL haptics are incarcerated into the prepared STs.

Results

The patients were followed up 5–8 months. None of the patients had complications such as postoperative endophthalmitis, glaucoma, IOL tilt or decentralization, and retinal detachment. Injection of a foldable IOL through a clear corneal small incision also contributes the less surgical-induced astigmatism.

Conclusion

The presented novel sutureless scleral IOL fixation technique may provide minimal trauma to the surrounding tissues, good IOL stabilization decreasing the incidence of IOL tilt along with shorter operation time, and postoperative quiet eye.     

Which Keratometer is Most Reliable for Correcting Astigmatism with Toric Intraocular Lenses?

Purpose

To evaluate the accuracy of preoperative keratometers used in cataract surgery with toric intraocular lens (IOL).

Methods

Twenty-five eyes received an AcrySof toric IOL implantation. Four different keratometric methods, a manual keratometer, an IOL master, a Pentacam and an auto keratometer, were performed preoperatively in order to evaluate preexisting corneal astigmatism. Differences between the true residual astigmatism and the anticipated residual astigmatism (keratometric error) were compared at one and three months after surgery by using a separate vector analysis to identify the keratometric method that provided the highest accuracy for astigmatism control.

Results

The mean keratomeric error was 0.52 diopters (0.17-1.17) for the manual keratometer, 0.62 (0-1.31) for the IOL master, 0.69 (0.08-1.92) for the Pentacam, and 0.59 (0.08-0.94) for the auto keratometer. The manual keratometer was the most accurate, although there was no significant difference between the keratometers (p > 0.05). All of the keratometers achieved an average keratometric error of less than one diopter.

Conclusions

Manual keratometry was the most accurate of the four methods evaluated, although the other techniques were equally satisfactory in determining corneal astigmatism.     

Optical quality of toric intraocular lens implantation in cataract surgery

AIM: To analyze the optical quality after implantation of toric intraocular lens with optical quality analysis system. METHODS: Fifty-two eyes of forty-four patients with regular corneal astigmatism of at least 1.00 D underwent implantation of AcrySof toric intraocular lens, including T3 group 19 eyes, T4 group 18 eyes, T5 group 10 eyes, T6 group 5 eyes. Main outcomes evaluated at 3mo of follow-up, included uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), residual refractive cylinder and intraocular lens (IOL) axis rotation. Objective optical quality were measured using optical quality analysis system (OQAS Ⅱ?, Visiometrics, Spain), included the cutoff frequency of modulation transfer function (MTFcutoff), objective scattering index (OSI), Strehl ratio, optical quality analysis system value (OV) 100%, OV 20% and OV 9% [the optical quality analysis system (OQAS) values at contrasts of 100%, 20%, and 9%]. RESULTS: At 3mo postoperative, the mean UDVA and CDVA was 0.18±0.11 and 0.07±0.08 logMAR; the mean residual refractive cylinder was 0.50±0.29 D; the mean toric IOL axis rotation was 3.62±1.76 degrees, the mean MTFcutoff, OSI, Strehl ratio, OV 100%, OV 20% and OV 9% were 22.862±5.584, 1.80±0.84, 0.155±0.038, 0.76±0.18, 0.77±0.19 and 0.78±0.21. The values of UDVA, CDVA, IOL axis rotation, MTFcutoff, OSI, Strehl ratio, OV100%, OV20% and OV9% depending on the power of the cylinder of the implantation were not significantly different (P>0.05), except the residual refractive cylinder (P<0.05). CONCLUSION: The optical quality analysis system was useful for characterizing the optical quality of AcrySof toric IOL implantation. Implantation of an AcrySof toric IOL is an effective and safe method to correct corneal astigmatism during cataract surgery.     

Oculentis区域折射多焦点人工晶状体植入术后早期疗效观察

目的：探讨Oculentis区域折射多焦点人工晶状体植入术后早期临床疗效。

方法：将2016-10/2017-01行超声乳化吸出术联合Oculentis区域折射多焦点人工晶状体植入术的白内障患者20例作为试验组,将同一时段行超声乳化吸出联合人类光学Aspira-aA单焦点非球面人工晶状体植入术的白内障患者20例作为对照组。检查患者术后3mo裸眼远视力、近视力、屈光状态、UBM检查、阅读戴镜率、不良体验率(光晕、眩光、雾视等现象发生率)的情况。

结果：术后3mo,试验组裸眼远视力(0.10±0.03)与对照组比较差异无统计学意义(t=1.74,P>0.05)。试验组裸眼近视力(0.11±0.04)与对照组比较差异有统计学意义(t=15.53,P<0.05)。术后3mo,试验组人工晶状体居中性均良好,阅读戴镜率为5%,不良体验率(光晕、眩光、雾视现象发生率)仅为5%,而对照组阅读戴镜率为100%。

结论：Oculentis区域折射多焦点人工晶状体植入术可提供良好的裸眼远视力和近视力,能极大地提高白内障术后脱镜率,解决白内障术后老视问题,且患者舒适度极佳,光晕、眩光、雾视现象少有发生,手术安全可靠。     

Clinical study of customized aspherical intraocular lens implants

AIM:To compare if there is an improvement in visual functions with age-related cataracts between patients receiving a aspherical intraocular lens (IOL) based on corneal wavefront aberration and patients randomly assigned lenses.METHODS:A total of 124 eyes of 124 patients with age-related cataracts were placed in experimental group and a group receiving randomly assigned (RA) lenses. The experimental group was undergone Pentacam corneal spherical aberration measurement before surgery; the targeted range for residual total spherical aberration after surgery was set to 0-0.3 μm. Patients with a corneal spherical aberration ＜0.3 μm were implanted with a zero-spherical aberration advanced optics (AO) aspherical IOL and patients with an aberration ≥0.3 μm received a Tecnis Z9003 aspherical lens in experimental group. RA patients were randomly implanted with an AO lens or a Tecnis Z9003 lens. Three months after surgery total spherical aberration, photopic/mesopic contrast sensitivities, photopic/mesopic with glare contrast sensitivities, and logMAR vision were measured.RESULTS:Statistical analysis on logMAR vision showed no significant difference between two groups (P=0.413). The post-surgical total spherical aberration was 0.126±0.097 μm and 0.152±0.151 μm in the experimental and RA groups, respectively (P=0.12). The mesopic contrast sensitivities at spatial frequencies of 6, 12 and 18 c/d in the experimental group were significantly higher than of the RA group (P=0.00; P=0.04; P=0.02). The mesopic with glare contrast sensitivity in the experimental group at a spatial frequency of 18 c/d was also significantly higher vs the RA group (P=0.01).CONCLUSION:Pre-surgical corneal spherical aberration measurement in cataract patients followed by customized selection of aspherical IOL implants improved mesopic contrast sensitivities at high spatial frequencies, and thus is a superior strategy compared to the random selection of aspherical IOL implants.     

Intra-ocular lens power calculation in patients with high axial myopia before cataract surgery

Purpose

To evaluate the accuracy of different formulas used for IOL power calculation in patients with high axial myopia undergoing cataract surgery.

Methods

A prospective clinical study was carried out on 53 eyes of 51 patients with an axial length from 25.5 to 31.4 mm including 21 males (41.2%) and 30 females (58.8%). Calculation of the IOL power to be implanted was done by three available IOL power formulas; Haigis formula, SRK/T formula, and Holladay I formula. The mean error (ME) was calculated from the difference between the formula predicted refractive error and the actual post operative refractive error.

Results

There was no statistically significant difference between the mean error of the three formulas used in the overall performance or in the axial length subcategories. SRK/T formula caused the smallest mean error, (+0.17 D). Haigis formula showed a higher ME (+0.21 D) and Holladay formula caused a myopic postoperative refractive error (−0.20 D).

Conclusion

The calculation of IOL power in patients with high axial myopia using the third or the fourth generation formulas help in improvement of the accuracy of the calculation and decreasing the post operative refractive error. SRK/T formula showed the lowest mean error, however, there was not statistically significant difference between the three formulas used, neither in the overall performance, nor in axial length subcategories.     

Glue-assisted intrascleral fixation of posterior chamber intraocular lens

Purpose:

To analyze the visual outcome of patients undergoing glue-assisted intrascleral fixation of posterior chamber intraocular lens (IOL) in the absence of posterior capsular support.

Materials and Methods:

This retrospective study analyzes 25 eyes which underwent IOL implantation by the glued intrascleral fixation technique. The pre and post-operative uncorrected visual acuity (UCVA), pre and post-operative best corrected visual acuity (BCVA), intraocular pressure (IOP), IOL position, anterior chamber reaction and central macular thickness were assessed and recorded. Immediate and late post-operative complications were also recorded.

Results:

A total of 25 eyes of 22 patients were reviewed and analyzed over a period of one year. All eyes had a foldable three-piece IOL implanted. About 84% of the eyes had a gain of one or more lines, 12% had no gain, and 4% had a fall of three lines of BCVA on Snellen''s visual chart, which was attributed to cystoid macular edema (CME). Postoperatively, there was a significant improvement in the UCVA (P < 0.05) and in the BCVA (P < 0.05). Postoperative complications included decentration in one case and vitritis with chronic macular edema in another case. Optical coherence tomography (OCT) demonstrated well placed IOL with no tilt.

Conclusion:

Although the results of one year follow-up of glued intrascleral fixation are promising, long term studies are recommended.     

Refractive accuracy after intraocular lens implantation in pediatric cataract

AIM: To analyze the factors that influence the prediction error (PE) after intraocular lens (IOL) implantation in pediatric cataract. METHODS: The medical records of cataract patients of no more than 14 years old who had primary IOL implantation were reviewed from 2006 to 2010. The PE, absolute value of PE (APE), and predictability between in different axial length, mean corneal curvature, corneal astigmatism, and age at the surgery were analyzed. RESULTS: Seventy-five children (119 eyes) were included, with a mean age of (5.09±2.54) years. At the follow-up of (1.19±0.69) months, the mean postoperative PE was (-0.22±1.12) D, and APE was (0.87±0.73)D. The PE in eyes with an axial length ＞20mm but ≤22mm were significantly under-corrected than that in eyes with longer axis, and the APE in eyes with an axial length ≤20mm was more obvious compared with the others. The correlations between PE and axial length, as well as corneal astigmatism, and between APE and axial length were significant. The predictability was significantly poorer in the eyes with an axial length ≤20mm than the others. CONCLUSION: The axial length is closely related with the PE after IOL implantation in pediatric cataract patients, especially when it is ≤20mm, PE is more significant. The formula that is more suitable to very short axial length should be explored.