Postoperative Refractive Error Research Articles

Secondary Sutureless Posterior Chamber Lens Implantation with Two Specifically Designed IOLs: Iris Claw Lens versus Sutureless Trans-Scleral Plugs Fixated Lens.

Background. The management of patients with aphakia and/or lack of capsular support remains debated. The sutureless posterior chamber IOL (PCIOL) fixation is a very useful surgical option. The purpose of the study was to compare the early outcomes as well as post-operative best corrected visual acuity, refractive errors and complications of two different techniques of sutureless PCIOL secondary implantation. Methods. Patients who underwent secondary implantation from December 2019 to January 2021 in the Department of Ophthalmology of Creteil Hospital, and in the Granville Ophthalmology Center, were retrospectively included. Eyes implanted with the iris claw lens (Artisan Aphakia IOL model 205, Ophtec BV, Groningen, The Netherlands) were included in group 1, and eyes implanted with a newly developed sutureless trans-scleral plugs fixated lens (STSPFL, Carlevale lens, Soleko, Pontecorvo, Italy) were included in group 2. Results. Twenty-two eyes of 22 patients were enrolled in group 1, and twenty eyes of 20 patients in group 2. No difference was found in visual acuity between two groups (0.35 +/− 0.29 logmar for group 1 and 0.23 +/− 0.51 logmar for group 2) (p = 0.15) at mean post-operative follow up (6.19 +/− 3.44 months for group 1 and 6.42 +/− 3.96 months for group 2) (p = 0.13). Both the mean refractive error (MRE) and induced astigmatism (IA) were greater in group 1 compared to group 2, respectively: the MRE was 0.99 +/− 0.57 vs. 0.46 +/− 0.36 (p < 0.01), and IA was 1.72 +/− 0.96 vs. 0.72 +/− 0.52 (p < 0.01). Conclusions. No significant differences in terms of the recovery of visual acuity were found between the two groups. Group 2 (STPFL) gives better results in our sample due to less post-operative induced astigmatism and less refractive error.

The Role of Anterior Chamber Depth on Post-operative Refractive Error After Phacovitrectomy.

PurposeTo investigate the effect of phacovitrectomy on the post-operative anterior chamber depth (ACD) and refractive outcomes, and to analyze the potential differences between vitreous filling with BSS, air and gas.MethodsPatients who underwent phacovitrectomy were included in this study and invited for repeated post-operative examination including refraction and biometry at least 3 months after the surgery. Data retrieved included demographic information, indication for phacovitrectomy, surgical details, type of vitreous filling (BSS, air or gas), pre-operative and post-operative biometric data including K-readings, axial length (AL), and ACD, as well as spherical equivalent (SE) values of the target and final refraction.ResultsForty-three eyes of 43 patients were included in this study, including 10 eyes filled with BSS, 18 with air and 15 with gas. The mean difference between the final measured spherical equivalent (SE) and the SE of the intended target refraction was 0.61±0.68 D (p = 0.019). Only 58.1% of eyes had a final SE within ±0.5D of the target refraction. Following surgery, AL remained unchanged, while mean pre-operative ACD increased significantly from 3.11±0.34 mm to 4.77±0.47 mm (p < 0.001). There was no difference in refractive error between the vitreous fillings and no correlation with AL or ACD.ConclusionsPhacovitrectomy is associated with lower accuracy of post-operative refraction compared to cataract surgery. This may be attributed to a significant change in ACD, influencing the effective lens position of the IOL, and may require adjustment of the pre-operative calculations.

Comparison of refractive outcomes using Scheimpflug Holladay equivalent keratometry or IOLMaster 700 keratometry for IOL power calculation.

This study aims to compare postoperative refractive error results using Pentacam (Oculus Optikgeräte GmbH) Holladay equivalent keratometry readings (EKR) or IOLMaster 700 (Carl Zeiss Meditec AG) keratometry (K) values in IOL power calculation. This retrospective study included 54 eyes of 31 patients who underwent cataract surgery. Preoperative biometric measurements of all patients were obtained using IOLMaster 700 followed by Pentacam measurements. IOLMaster 700K measurements on horizontal (K1) and vertical (K2) axes and EKR measurements on 2mm (EKR2mm), 3mm (EKR3mm) and 4.5mm (EKR4.5mm) corneal zones were recorded. EKR4.5mm value and IOLMaster 700K values were used in Holladay-II, SRK/T, Haigis, and Hoffer-Q formulas to calculate predictive refractive error (PRE). Absolute refractive error (ARE) was calculated as the absolute difference between actual postoperative refractive error (APRE) and PRE values. Mean age was 72.2 ± 8.3 (51-87) years and mean IOL power was 21.5 ± 2.9 D (18-23 D). There was no significant difference between PRE values when IOLMaster 700K measurements and EKR4.5mmK measurements were used in Holladay-II, SRK/T, Haigis, and Hoffer-Q formulas (p = 0.571, p = 0.833, p = 0.165, p = 0.347, respectively). There was no significant difference between APRE and ARE values (p = 0.124). According to mean ARE results, the closest estimate was achieved when the IOLMaster 700K values were used in the Holladay-II formula (p = 0.271). IOLMaster 700K measurement and Pentacam EKR4.5mm measurements can be used interchangeably. IOLMaster 700K values yielded the most predictive measurement of the refractive result using the Holladay-II formula.

Accuracy of intraocular lens calculation formulas for eyes with insufficient capsular support.

BackgroundThere is no consensus on which intraocular lens (IOL) power calculation formula provides the best refractive prediction in patients with inadequate capsular support whose anterior ocular anatomic structure differs from that of normal subjects. Therefore, the purpose of this study was to analyze the accuracy and performance of IOL calculation formulas (SRK/T, Holladay 1, Hoffer Q, Haigis, and Barrett Universal II) in predicting postoperative refractive prediction error (PE) for this subgroup of patients.MethodsA total of 110 eyes from 110 patients with insufficient capsular support who underwent scleral fixation of an IOL at the Zhongshan Ophthalmic Center from July 1, 2016 to November 30, 2019 were enrolled in this retrospective study. Preoperative optical biometrics were measured with the IOL Master 500 (Carl Zeiss, Oberkochen, Germany). The performance of each formula in predicting PE was compared, and the effect of keratometry and axial length (AL) on PE was evaluated for each formula using univariate and multivariate linear regression analysis.ResultsThe mean age of the included participants was 12.54±9.66 years. The Sanders, Retzlaff, and Manus/theoretical (SRK/T) (−0.25 D) and Holladay 1 (−0.28 D) formulas tended to have minimal postoperative PE compared to the Hoffer Q (−0.62 D), Haigis (−0.67 D), and Barrett Universal II (−0.62 D) formulas (P=0.005). All formulas individually resulted in <70% of eyes within ±1.00 D of the PE. Nevertheless, after constants were optimized, these formulas led to 7.3% to 13.6% of increase within ±1.00 D of the PE. Keratometry and AL were significantly associated with PE for each formula, but the relationship was weakest for SRK/T.ConclusionsIn eyes with insufficient capsular support, postoperative PE was minimal for the SRK/T formula, which suggested SRK/T to be the best choice, especially when the keratometry and AL of patients are extremely large or small.

Intraocular lens power calculation for plus and minus lenses in high myopia using partial coherence interferometry

PurposeWe assessed the accuracy of lens power calculation in highly myopic patients implanting plus and minus intraocular lenses (IOL).MethodsWe included 58 consecutive, myopic eyes with an axial length (AL) > 26.0 mm, undergoing phacoemulsification and IOL implantation following biometry using the IOLMaster 500. For lens power calculation, the Haigis formula was used in all cases. For comparison, refraction was back-calculated using the Barrett Universal II (Barrett), Holladay I, Hill-RBF (RBF) and SRK/T formulae.ResultsThe mean axial length was 30.17 ± 2.67 mm. Barrett (80%), Haigis (87%) and RBF (82%) showed comparable numbers of IOLs within 1 diopter (D) of target refraction. Visual acuity (BSCVA) improved (p < 0.001) from 0.60 ± 0.35 to 0.29 ± 0.29 logMAR (> 28-days postsurgery). The median absolute error (MedAE) of Barrett 0.49 D, Haigis 0.38, RBF 0.44 and SRK/T 0.44 did not differ. The MedAE of Haigis was significantly smaller than Holladay (0.75 D; p = 0.01). All median postoperative refractive errors (MedRE) differed significantly with the exception of Haigis to SRK/T (p = 0.6): Barrett − 0.33 D, Haigis 0.25, Holladay 0.63, RBF 0.04 and SRK/T 0.13. Barrett, Haigis, Holladay and RBF showed a tendency for higher MedAEs in their minus compared to plus IOLs, which only reached significance for SRK/T (p = 0.001). Barrett (p < 0.001) and RBF (p = 0.04) showed myopic, SRK/T (p = 002) a hyperopic shift in their minus IOLs.ConclusionsIn highly myopic patients, the accuracies of Barrett, Haigis and RBF were comparable with a tendency for higher MedAEs in minus IOLs. Barrett and RBF showed myopic, SRK/T a hyperopic shift in their minus IOLs.

DIFFERENCE BETWEEN TARGET AND POST OPERATIVE REFRACTIVE ERROR FOLLOWING CONGENITAL CATARACT SURGERY IN PAEDIATRIC PATIENTS VISITING ARMED FORCES INSTITUTE OF OPHTHALMOLOGY

Objective: To determine the difference between target and postoperative refraction in children with congenital cataract.&#x0D; Study design: Prospective interventional study&#x0D; Place and Duration of Study: This study was conducted at Armed Forces Institute of Ophthalmology from May 2017 to May 2018.&#x0D; Methods: This study was conducted on 38 eyes suffering from congenital cataract. Age at the time of surgery, axial length, average keratometry reading, estimated refraction, and the power of IOL implanted were recorded. Spherical equivalent of post-op refraction at 3 months after surgery was noted. The difference between the estimated and actual postoperative refraction was termed as prediction error. Age, keratometry, and axial length were then assessed for its effects on prediction error.&#x0D; Results: Overall the mean prediction error was 1.43±1.98 D. The mean prediction errors in eyes with axial lengths ⩾20 mm were 0.96± 1.03 D and in eyes &lt;20 mm were 5.50± 3.49 D. The mean prediction errors in eyes in children aged ⩾4 years were 0.14± 0.61 D) and in children aged &lt; 4 years was 2.60± 2.07 D. The differences between the prediction errors for both axial length and age were statistically significant (p&lt;0.05).&#x0D; Conclusion: IOL power calculations in eyes with axial length less than 20 mm and children less than 4 years of age are prone to postoperative refractive errors. This study has reflected that adult based formulas are not reliable in pediatric age group.

Combined versus Sequential Phacoemulsification and Pars Plana Vitrectomy: A Meta-Analysis

It is unclear whether differences exist in efficacy and safety between combined versus sequentially performed phacoemulsification and pars plana vitrectomy (phaco-PPV). This meta-analysis aimed to compare the efficacy and incidence of complications between these surgical methods. Ovid MEDLINE, EMBASE, and Cochrane CENTRAL were searched for articles reporting the efficacy and safety of combined versus sequential phaco-PPV for any indication. The primary outcomes were postoperative best-corrected visual acuity (BCVA) and mean absolute refractive error from target (RET). Secondary outcomes included efficacy outcomes and postoperative complications. Meta-analysis was conducted using a random effects model in all cases. Risk of bias assessment was performed using the Cochrane risk of bias assessment tool for randomized trials and ROBINS-I tool for observational studies. Of the 5410 articles identified, 1 randomized controlled trial and 14 comparative studies were included, with 1407 and 951 eyes in the combined and sequential surgery groups, respectively. Mean age was 62.71 ± 6.16 years and 44% (range, 32.1%-70%) of eyes were from men. The mean baseline BCVA was 0.88±0.59 logarithm of the minimum angle of resolution units (Snellen equivalent, 20/152). The meta-analysis showed no significance between groups in postoperative mean BCVA (P= 0.76) and mean absolute RET (P= 0.46). The risks of synechiae formation (risk ratio [RR], 2.74; 95% confidence interval [CI], 1.83-4.11; P < 0.001), fibrin formation (RR, 2.81; 95% CI, 1.84-4.30; P < 0.001), and intraoperative or postoperative retinal detachment (RR, 2.65; 95% CI, 1.08-6.47; P= 0.03) were significantly higher after combined surgery. However, the risks of posterior capsular tear (RR, 0.43; 95% CI, 0.25-0.73; P= 0.002) and macular hole nonclosure or reopening (RR, 0.18; 95% CI, 0.03-0.93; P= 0.04) were significantly lower in the combined group. No significant differences were found in visual and refractive outcomes between combined and sequential phaco-PPV, whereas differences existed in certain safety outcomes. These conclusions remain preliminary, as most evidence is derived from low- to moderate-quality retrospective studies. Given the variability in outcome reporting and associated heterogeneity, future randomized controlled trials are needed.

Intraocular lens power calculation formula in congenital cataracts: Are we using the correct formula for pediatric eyes?

The major challenge these days in pediatric cataract surgery is not the technique of surgery or intraocular lens (IOL) used but the postoperative refractive error. Amblyopia occurring due to postoperative refractive error which the child has; destroys the benefit obtained by a near-perfect and timely surgery. Even if we settle the debate as to what should be the ideal postoperative target refraction, there is a postoperative surprise that is not explained by our conventional insights of an accurate power calculation in children. The role of IOL power calculation formulae in affecting the postoperative refractive error should not be underestimated. Therefore, which age-appropriate formula is to be used for children is unclear. This review is an update on major IOL power calculation formulas used in pediatric eyes. We have tried to define why we should not be using these formulas made for adult eyes and review the literature in this regard.

Investigation of the Precision of Postoperative Refractive Error Prediction Calculated Using the Barrett TK Universal II and Other Formulas

Investigation of the Precision of Postoperative Refractive Error Prediction Calculated Using the Barrett TK Universal II and Other Formulas

Method for IOL Power Calculation in the Second Eye of Patients With Previous Keratorefractive Surgery.

To describe and evaluate a method for calculating intraocular lens (IOL) power in the second operative eye of patients with a history of keratorefractive surgery. All eyes had undergone cataract surgery by a single surgeon from 2015 to 2018. Postoperative outcomes on the first eye (eg, IOL power implanted and postoperative refractive error) were used to back calculate a "Real K" for the first eye. The difference (delta) between the second and first eye topographic simulated keratometry values was then added to the first eye Real K to calculate the second eye Real K. This Real K value was inputted into the Holladay IOL Consultant software as an "alternate K" to derive an accurate IOL power for the second eye. Mean absolute error, mean error, and percentage of eyes on target using the Delta K method were compared with results obtained with intraoperative abserrometry and the Haigis-L and Barrett True-K No History formulas. The mean error for the Delta K method was significantly better than the Haigis-L (P = .00001) and Barrett True-K No History (P = .027) formulas, and on par with intra-operative aberrometry (P = .25). The mean absolute error of the Delta K method was significantly better than the Haigis-L formula (P = .03). The Delta K mean absolute error was on par with intraoperative aberrometry (P = .81) and the Barrett True-K No History formula (P = .56). The Delta K mean absolute error is comparable to the Barrett True-K No History formula. The mean error is lower than that calculated with the Barrett True-K No History formula and comparable to intraoperative aberrometry. [J Refract Surg. 2020;36(12):826-831.].

Corneal Topography for Intraocular Lens Selection in Refractive Cataract Surgery

The purpose of this review is to evaluate the usefulness of corneal topography to select premium intraocular lenses (IOLs), including aspherical IOLs, toric IOLs, and multifocal IOLs, in refractive cataract surgery. Corneal topography can detect corneal regular astigmatism, corneal irregular astigmatism (higher-order aberrations [HOAs]) including spherical aberration, and corneal shape abnormalities after corneal refractive surgery. Surgeons can explain to the patients with significant corneal HOAs about its effect on postoperative visual function before surgery. Multifocal IOLs should not be selected for such eyes. For eyes with abnormal corneal shape, appropriate IOL power calculation formulae can be applied. In the case of toric IOLs, regular astigmatism and corneal HOAs should be checked. Before implanting an aspheric IOL, it is ideal to confirm spherical aberration of the cornea is not below the normal range. Because corneal HOAs, abnormal corneal shape after corneal refractive surgery, corneal regular astigmatism, and corneal spherical aberration increase postoperative refractive errors and poor vision quality with premium IOLs, corneal topography before cataract surgery is helpful in screening patients who are not appropriate candidates for premium IOLs.

Clinical Outcomes of the Scleral Fixation of Posterior Chamber Intraocular Lens using the Modified Yamane's Technique: a Swept-source Optical Coherence Tomography Study

To observe the postoperative outcomes of the scleral fixation of posterior chamber intraocular lens (SF-PCIOL) using the modified Yamane's technique with the aid of swept-source optical coherence tomography (SS-OCT). Prospective observational case series. This study involved 20 patients who underwent SF-PCIOL with the modified Yamane's technique, from December 2017 to November 2019. All patients had routine preoperative examinations, including biometric measurement by IOL master, measurements of uncorrected distance visual acuity (UDVA) and best corrected distance visual acuity (BCDVA). The SRK/T formula was used to calculate the power of intraocular lens (IOL). After the surgery, UDVA and intraocular pressure were evaluated for 1 d, UDVA, BCDVA, spherical equivalent (SE) and corneal endothelial cell density were measured for 1 week, 1 month, 3 and 6 months, respectively. The IOL tilt and the symmetry of hepatitis in the scleral tunnel were measured by SS-OCT. The mean follow-up duration was (7.20±6.56) months (range, 3-26 months). The mean preoperative UDVA was (1.70±0.38) LogMAR, and it improved to (0.48±0.50) LogMAR ( P=0.001). There was no statistically significant difference between the pre- and post-operative BCDVA, i.e. (0.44±0.50) LogMAR and (0.32±0.48) LogMAR, respectively ( P=0.08). The mean spherical equivalent was (-0.53±0.86) diopter (D) and the postoperative refractive error was (0.27±0.82) D. Seventeen patients underwent SS-OCT examinations. The mean IOL tilt was (3.28±3.00)°. There was no significant difference between the horizontal and vertical tilt ( P=0.326). The IOL tilt did not show a significant correlation with spherical and cylindrical refractive error ( P=0.532, P=0.241). There was no statistically significant difference in the HL (the length of haptics fixed in the scleral tunnel) of nasal and temporal haptic, which were (2.24±0.20) mm and (2.17±0.23) mm, respectively ( P=0.193). And there were no statistically significant differences between the HD (the distance between the center of haptic flange and scleral spur) of nasal and temporal haptic, (1.58±0.07) mm and (1.66±0.08) mm, respectively ( P=0.338). The changes of IOL haptics in the scleral tunnel were tracked by 10 patients. The HL (nasal: HL-N; temporal: HL-T) and the HD (nasal: HD-N; temporal: HD-T) of haptics in the tunnel were measured and recorded at three time points, including 1 week, 1 and 3 months after surgery. There was no significant difference in HL-N, HL-T, HD-N and HD-T at the three time points ( P=0.931, P=0.091, P=0.175, and P=0.505, respectively). All patients underwent uneventful surgery. The postoperative complications included transient corneal edema in 6 eyes, transient IOP elevation in 3 eyes, vitreous hemorrhage in 1 eye, cystoid macular edema in 2 eyes, and macular hole in 1 eye. The SF-PCIOL using modified Yamane's technique, is capable of producing satisfactory and consistent postoperative outcomes for patients with few postoperative complications. SS-OCT is a powerful tool for measuring optic tilt and the IOL hepatic symmetry in scleral tunnel.

Clinical Outcomes and Lens Constant Optimization of the Zeiss CT Lucia 602 Lens Using a Modified Yamane Technique.

PurposeTo report the clinical and refractive outcomes of a modified Yamane technique for scleral fixation of the CT Lucia 602 lens.DesignRetrospective case series.PatientsOne hundred twenty-one eyes with dislocated posterior chamber lens implants, surgical aphakia, subluxed crystalline lenses, capsular tear, anterior chamber, or iris sutured posterior chamber lens intolerance were included.MethodsSecondary implantation of the Zeiss CT Lucia 602 lens was performed by a single surgeon using a modified Yamane technique employing a single needle, rather than the double-needle approach. One hundred twelve eyes underwent simultaneous 3 port pars plana vitrectomy and 9 eyes had previously undergone posterior vitrectomy surgery. Exclusion criteria were age <18, simultaneous glaucoma or corneal procedures, staged corneal transplantation, and follow-up <30 days.Main Outcome MeasuresA paired t-test was used to compare pre- and post-operative corrected distance visual acuity (CDVA), the mean predictive error, and the mean absolute predictive error between the manufacturer’s and optimized constants for Hoffer Q, Holladay I, and SRK/T. Complication rates were reported.ResultsOne hundred twenty-one consecutive eyes with a mean follow-up of 237 days were included. The pre-operative CDVA was 0.871 ± 0.785 logMAR (mean ± standard deviation, Snellen equivalent 20/149), which improved to 0.401 ± 0.608 (Snellen equivalent 20/50) post-operatively. In 109 eyes with reliable postoperative refractions, the mean predictive refractive error (D) ± std was +0.74 ± 1.37 for Hoffer Q, +0.66 ± 1.41 for Holladay 1, and +0.47 ± 1.49 for SRK/T (p<0.05). Refractive outcome analysis yielded a mean optimized personalized anterior chamber depth (pACD) of 5.69, Surgeon Factor of 1.79, and A constant of 118.56. Vision-limiting complications occurred in 11 eyes (9.1%).ConclusionScleral fixation of the CT Lucia 602 lens using a single-needle modification of the Yamane technique resulted in very good visual acuity, predictable postoperative refractive errors, but some vision-limiting complications in this heterogeneous group of eyes with significant comorbidities.

Artificial intelligence in global ophthalmology: using machine learning to improve cataract surgery outcomes at Ethiopian outreaches.

Differences between target and implanted intraocular lens (IOL) power in Ethiopian cataract outreach campaigns were evaluated, and machine learning (ML) was applied to optimize the IOL inventory and minimize avoidable refractive error. Patients from Ethiopian cataract campaigns with available target and implanted IOL records were identified, and the diopter difference between the two was measured. Gradient descent (an ML algorithm) was used to generate an optimal IOL inventory, and we measured the models performance across varying surplus levels. Only 45.6% of patients received their target IOL power and 23.6% received underpowered IOLs with current inventory (50% surplus). The ML-generated IOL inventory ensured that more than 99.5% of patients received their target IOL when using only 39% IOL surplus. In Ethiopian cataract campaigns, most patients have avoidable postoperative refractive error secondary to suboptimal IOL inventory. Optimizing the IOL inventory using this ML model might eliminate refractive error from insufficient inventory and reduce costs.

Efficacy of Combined Suprachoroidal Stent and Cataract Surgery in Patients With Glaucoma.

The purpose of this study was to evaluate the efficacy of intraocular pressure (IOP) control after combined CyPass Micro-Stent implantation and cataract surgery (combined surgery). All cases of combined surgery performed from February 2017 to July 2018 at Stein and Doheny Eye Institutes were reviewed. The primary outcome was a qualified success with stratified IOP targets based on criteria: final IOP (A) ≤18 mm Hg and reduction of 20%, (B) ≤15 mm Hg and reduction of 25%, (C) ≤12 mm Hg and reduction of 30%. Secondary outcome measures included postoperative IOP and number of medications, complications, additional glaucoma surgery, and postoperative refractive error. Predictive factors for failure were investigated. IOP spike was defined as a postoperative IOP ≥30 or >10 mm Hg increase from preoperative IOP. One hundred forty-one eyes (107 patients) were included. Mean (±SD) preoperative IOP was 15.4±3.4 mm Hg on an average of 2.2±1.1 medications. A statistically significant reduction in IOP and number of medications was seen at 12 months (13.8±4.2 mm Hg, 1.3±1.3 medications, P<0.001). Fifteen eyes (10.6%) had a postoperative IOP spike. Thirteen eyes (9.2%) experienced 17 complications (12.1%). Additional glaucoma surgery was performed in 3 eyes (2 patients). Cumulative success rates at 1 year based on criteria A, B, and C were 42%, 33%, and 28%, respectively. Lower preoperative IOP, greater preoperative medication number, the occurrence of postoperative IOP spike, and non-Caucasian ethnicity were associated with failure. Combined CyPass Micro-Stent implantation and cataract surgery may reduce glaucoma medication burden with a success rate of 28% to 42% at 1 year.

Intraocular lens power calculation in eyes with keratoconus

The purpose was to review and document the methods used to calculate the power of the intraocular lens (IOL) to be implanted in cataract surgery in the specific scenario of eyes with keratoconus. This review included all scientific articles published in English that focused on the parameters and formulas used to calculate the power of the IOL to be implanted in eyes with keratoconus undergoing cataract surgery. There are few publications that show in detail how IOL power is calculated in these particular cases. If the keratometric value used was based on the standard refractive index (1.3375), it resulted in a postoperative refractive error with a tendency to hyperopia. The SRK/T formula yielded the best outcomes. The greater the severity of keratoconus the greater was the deviation of the postoperative refractive status from the target outcome.

Effect of capsular tension ring implantation on predicted refractive error after cataract surgery in patients with pseudoexfoliation syndrome.

To investigate the effect of capsular tension ring (CTR) implantation on predicted refractive error after cataract surgery in patients with pseudoexfoliation (PEX) syndrome. This double-blind randomized clinical trial was conducted on 60 patients with PEX syndrome referring to Imam Khomeini Hospital affiliated to Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran, for undergoing cataract surgery. The study population was divided into two groups, namely CTR group (n=30) and non-CTR group (control group; n=30). The refractive error and anterior chamber depth (ACD) were measured 1wk, 1mo, and 3mo after phacoemulsification (PE) surgery. The results indicated no statistically significant difference between the two groups in terms of predicted refractive error (obtained by subtracting preoperative predicted refractive error from actual postoperative refractive error) 1wk (P=0.47), 1mo (P=0.30), and 3mo (P=0.06) after the PE surgery. Regarding the CTR group, the changes of ACD was statistically significant 1 and 3mo after the PE surgery, compared to those obtained 1wk post-surgery (P=0.005). The CTR implantation in PEX cataractous patients without zonulysis has no statistically significant effect on the predicted refraction and ACD changes after PE. The predicted refraction error has a hyperopic shift in both groups. The results reveal the unnecessary of calculating modified IOL in CTR implantation.

Burden and Factors Associated with Refractive Errors Post Cataract Surgery at Kilimanjaro Christian Medical Center: A Hospital Based Retrospective Cross-sectional Study

Aims: To determine the burden and factors associated with refractive errors after cataract surgery in a training institution.&#x0D; Study Design: A retrospective cross-sectional study.&#x0D; Place and Duration of the Study: Kilimanjaro Christian Medical Center Eye department. Northern Tanzania, from January 2016 to December 2017.&#x0D; Methods: A review of files of all adult patients who have had cataract surgery in 2016 and 2017 was conducted. A total of 626 eyes of 554 patients who had post-operative refraction by experienced optometrists were included. Information were extracted from patients’ files then entered into SPSS version 20 for analysis. The main outcomes were post-operative refraction and best corrected visual acuity. &#x0D; Results: Mean age was 69.3 years (SD=10.7) and ECCE accounted for 76% of surgeries. At least 84.6% had post-operative refractive error and astigmatism was the most common refractive error (56.8%). Spherical error accounted for 27.8%. Spherical error ranged from -12 to 4DS, mean = -0.42 (SD=1.3) DS and median = 0.00DS. The maximum cylindrical error was -7.5 DC, mean = -1.15 (SD=1.36) DC and median = -1.0DC. At least 56% had spherical equivalent within 1D of emmetropia. A BCVA of 6/18 or better was achieved in 92.8%. Age, poor pre-operative VA, poor presenting VA, astigmatism on keratometry, difference between recommended and inserted IOL, ECCE, grade of surgeon and suturing were associated with refractive errors.&#x0D; Conclusion: Refractive errors following cataract surgery are common. Best corrected visual acuity outcome was in normal recommended range; however, the magnitude of refractive errors was high and the proportion of patients who achieved a final refraction within 1D of emmetropia was below the recommended range. An effort should be made to lower the prevalence and magnitude of refractive errors associated with cataract surgery in training institutions.

Comparison of Two Different Accelerated Corneal Cross-linking Procedure Outcomes in Patients with Keratoconus

Background:Corneal cross-linking treatment is the unique treatment method that can cease the progression of keratoconus disease. Because of the long duration of conventional treatment, accelerated cross-linking treatment methods are being developed.Aims:To compare two different accelerated corneal cross-linking protocols in terms of postoperative visual acuity and topographic findings (higher-order aberrations and keratometry values).Study Design:Retrospective comparative study.Methods:Sixty-five eyes of 43 patients (30 men and 13 women) who underwent two different accelerated corneal cross-linking protocols (10 min, 9 mW/cm2 and 5 min, 18 mW/cm2) for progressive keratoconus were retrospectively analyzed. Patients were divided into two groups according to the accelerated corneal cross-linking treatment protocol: group 1 (10 min, 9 mW/cm2, 32 eyes of 21 patients) and group 2 (5 min, 18 mW/cm2, 33 eyes of 22 patients). Uncorrected visual acuity and best-corrected visual acuity values and topographic findings (central corneal thickness and flat and steep keratometry values) were recorded preoperatively and 6 months after corneal cross-linking treatment. High-order aberration values measured with Pentacam preoperatively and 6 months after corneal cross-linking were also recorded.Results:In both groups, a significant improvement was detected in the uncorrected visual acuity and best-corrected visual acuity levels preoperatively and 6 months postoperatively (group 1: p=0.001, p=0.001 and group 2: p=0.001, p=0.001, respectively). In addition, central corneal thickness values decreased significantly in both groups (p=0.006 and 0.001). Trefoil values showed no significant difference preoperatively and 6 months postoperatively in group 1 (p=0.160 and 0.620, respectively). In groups 1 and 2, coma values were found to decrease significantly in the 6th postoperative month compared with preoperative values (p=0.001 and 0.020, respectively). There was no significant difference between preoperative and 6th month postoperative horizontal and vertical trefoil values in both groups (p=0.850 and 0.140, respectively). There was no significant difference between the two groups in terms of preoperative and 6th month postoperative higher-order aberrations, refractive errors, keratometry values, and uncorrected visual acuity and best-corrected visual acuity levels.Conclusion:Both accelerated corneal cross-linking procedures provide similar improvement in topographic findings, coma values and visual acuity.

Topography-Guided Refractive Astigmatism Outcomes: Predictions Comparing Three Different Programming Methods.

PurposeTo identify the laser programming strategy that will achieve optimal refractive outcomes of LASIK with a topography-guided laser for eyes with a disparity between cylinder measured by manifest refraction and cylinder measured by topography.SettingSix surgeons at 5 clinical sites in the USA.DesignRetrospective data review.MethodsPreoperative, treatment, and postoperative data on 52 eyes that underwent topography-guided LASIK with the WaveLight EX500 Contoura® Vision excimer laser ablation profile in which the vectors representing the preoperative refractive cylinder and the cylinder measured by the WaveLight® Topolyzer™ VARIO Diagnostic Device (Vario cylinder) differed by >/= 0.50D and/or >/= 10 degrees of orientation were analyzed retrospectively. Data were contributed by six surgeons using the laser at 5 different clinical sites. Vector analysis of postoperative cylindrical refractive error and the actual laser programming strategy was used to calculate the cylindrical correction that would, theoretically, have completely eliminated postoperative refractive cylinder. This was compared to expected results using the preoperative manifest cylinder, the topographic cylinder, and the Phorcides Analytic Engine (Phorcides LLC, North Oaks MN; Phorcides). For analysis, subjects were stratified on the basis of the vector difference between Manifest and Topo cylinder (High, >0.75 D; and Low, ≤0.75 D).ResultsThe poorest calculated theoretical outcomes were obtained with the manifest refraction (centroid: −0.43, 0.22; mean calculated error vector: 0.56 ± 0.42 D; p=ns). Better outcomes were obtained with the topographically measured refraction (centroid: 0.37, 0.02; mean calculated error vector: 0.47 ± 0.33 D; p=ns). The best outcomes were obtained with Phorcides (centroid: −0.15, 0.06; mean calculated error vector: 0.39 ± 0.28 D; p=ns). The mean error vector magnitude in the Phorcides Low group was significantly lower than for the Manifest and Topo Low groups (0.26 D vs 0.48 D and 0.33 D; p<0.01). The mean error magnitude in the Phorcides High group was nearly 0.25 D lower than for the Manifest High group (0.48 D vs 0.70 D; p<0.01), but was the same as for the Topo High group (0.48 D vs 0.48 D).ConclusionOur study suggests that using the topographically measured cylinder or the cylinder selected by Phorcides will produce more desirable refractive outcomes than entry of the preoperative refractive cylinder as the basis for correction of myopia and myopic astigmatism with the WaveLight Contoura Vision excimer laser.