Re-inventing the straight incision with a single central suture in manual small-incision cataract surgery to minimize surgically induced astigmatism.

Purpose: To calculate the surgically induced astigmatism (SIA) in MSICS through a superiorly placed straight scleral incision closed with a single, central, perpendicular 10-0 polyamide suture and to document any suture-related complaints and complications. Methods: A retrospective, hospital-based study was carried out in 50 cases of uncomplicated senile cataract (>50 year) with nuclear sclerosis ≥ grade 4, "with the rule" astigmatism who underwent MSICS through a superior, straight incision with a single, central, perpendicular 10-0 nylon suture. Patients with "against the rule" astigmatism, keratoconus, pre-existing corneal opacity, astigmatism >2D, distorted or oblique mires, and previous ocular surgeries and unwilling to participate were excluded. Results: The mean age of the patients was 64.81 + 2.824 years, with a male: female ratio of 1.38:1. The mean SIA at day 7, week 6, and 12 weeks was 0.539 + 0.118, 0.529 + 0.134, and 0.524 + 0.129, respectively. Only 6 patients (12%) complained of foreign body sensation. No patient developed any suture-related complications. Conclusion: SIA is significantly reduced in straight incision by applying a single, central, and perpendicular 10-0 polyamide suture, as compared to a straight incision without a suture.

Assessment of a software guided system to reduce pre-existing astigmatism in cataract surgery.

The aim of this pilot study was to assess the astigmatism after small incision cataract surgery by use of a novel software guided surgical technique. The software system guides the surgeon toward a hypothetical shape of the cornea. When this shape is achieved, the vertical meridian is relaxed and the incision does not produce any astigmatism. How that hypothetical shape is to be achieved by the surgeon is described. If preoperative astigmatism exists, the hypothetical shape calculated by the system takes that into account. This enables the surgeon to reduce preexisting astigmatism, without having to change the site or size of the standard 6 mm 12 o clock incision of SICS. Results: Results indicated that preoperative astigmatism reduced in 11 out of 14 cases at the end of 8 weeks, remained unchanged in one, and increased by less than 0.5D in two cases. This proves the hypothesis that the vertical corneal meridian is under higher tension and relaxing it by flattening the perpendicular meridian has a reducing effect on postoperative astigmatism.

Merits of conjunctival frill incision in reducing trabeculectomy-induced astigmatism and patient discomfort.

Purpose: To compare results of a novel "conjunctival frill/smile incision" on surgically induced astigmatism (SIA) and patient discomfort vs conventional trabeculectomy in the initial postoperative period. Methods: Sixty trabeculectomy cases were subjected to either conjunctival frill incision, performed 1.5-2.0 mm from the limbus (study group) or conventional fornix-based conjunctival flap (control group). Corneal astigmatism and suture-induced discomfort were assessed by keratometry and a self-devised patient questionnaire, respectively. Results: Both groups generated a "with the rule" SIA, which was 1.77 vs 2.42 at 1 week and reduced to 1.27 vs 1.8 in the study vs control group, after removal of sutures - both scleral flap releasable and conjunctival at 1 month. Patient discomfort score revealed enhanced comfort in 37% of patients (study group) vs 17% (control group) during the early postoperative period. After 1 month of surgery, good comfort was regained in all cases. Conclusion: This novel suturing technique results in reduced SIA, patient discomfort during the 1st month after trabeculectomy.

Minimizing surgically induced astigmatism in non-phaco manual small incision cataract surgery by U-shaped modification of scleral incision.

PURPOSE: To evaluate the amount and type of surgically induced astigmatism (SIA) in manual small incision cataract surgery (SICS) with a 4.5 mm U-shaped scleral incision. METHODS: A prospective cross-sectional study was done on a total of 61 patients above 40 years of age with senile cataract. All patients underwent complete examination including preoperative uncorrected visual acuity (UCVA), refraction, best-corrected visual acuity (BCVA), and keratometry using a manual keratometer (Bausch and Lomb). All 61 patients underwent manual SICS with a 4.5 mm U-shaped scleral incision within the astigmatic neutral incisional funnel. Patients were thoroughly examined on immediate postoperative day 1 and findings of UCVA, BCVA, refraction, and keratometry were noted at the end of the 1st week, 4th week, and 6th week follow-up visits. SIA was calculated for all the follow-ups using the SIA calculator version 2.1, a free software program. The changes in the amount and type of postoperative SIA were tested for statistical significance using Fischer's exact test. Variance was tested using intraclass score effect. The threshold for statistical significance was set to P < 0.001. RESULTS: Postoperatively, the average SIA was 0.43 ± 0.13 D at the end of 1st week, 0.29 ± 0.20 D at the end of the 4th week, and remained the same 0.29 ± 0.21 D at the end of 6th week. The type of astigmatism shifted more towards against-the-rule (ATR) type in 45.9% of cases during the final postoperative follow-up. CONCLUSION: In our study, we conclude that the incision within the funnel of astigmatic neutralization is one of the major determinants of SIA in manual SICS. We were able to achieve phacocomparable SIA in our study mainly because of our type of incision.

Prevention and management of refractive prediction errors following cataract surgery.

Patient satisfaction after modern day cataract surgery requires excellent surgical technique but increasingly demands superior refractive outcomes as well. In many cases, there exists an expectation from patients, as well as surgeons, to achieve emmetropia after cataract surgery. This is particularly true in patients electing premium intraocular lens technology to correct astigmatism and presbyopia to minimize spectacle dependence. Despite continued advances in preoperative and intraoperative diagnostics, refractive planning, and surgical technology, residual refractive error remains a primary source of dissatisfaction after cataract surgery. The need to enhance refractive outcomes and treat residual astigmatic or spherical refractive errors postoperatively becomes paramount to meeting the expectations of patients in their surgical outcome. This article reviews the potential preoperative and intraoperative pitfalls that can be the source of refractive error, the various options to enhance refractive outcomes, and potential future technologies to limit residual refractive error after cataract surgery.

Long-term comparison of postoperative refractive outcomes between phacotrabeculectomy and phacoemulsification.

PURPOSE: To compare long-term postoperative refractive outcomes between phacotrabeculectomy and phacoemulsification, both with posterior chamber intraocular lens implantation. SETTING: Department of Ophthalmology, Konyang University, Kim's Eye Hospital, Myung-Gok Eye Research Institute, Seoul, South Korea. DESIGN: Retrospective comparative study. METHODS: Postoperative refractive outcomes were compared between patients with cataract and coexisting primary or secondary open-angle glaucoma (OAG) who had phacotrabeculectomy (combined group) and patients with cataract with or without coexisting OAG who had phacoemulsification alone (phaco-only group). The refractive prediction error, mean absolute error, and median absolute error were compared between groups. Subgroup analysis based on preoperative axial length (AL) was performed (medium >22.0 to <24.5 mm; medium-long ≥24.5 to <26.0 mm; long ≥26.0 mm). RESULTS: The combined group comprised 51 eyes and the phaco-only group, 74 eyes. The mean interval between surgery and refraction measurement was 14.70 months ± 10.80 (SD) (median 13.0 months) and 4.81 ± 4.97 months (median 2.0 months), respectively. Postoperatively, there was no statistically significant between-group difference in the following mean values: refractive prediction error, -0.05 ± 0.64 versus -0.04 ± 0.52 (P = .905); mean absolute error, 0.46 ± 0.44 versus 0.38 ± 0.36 (P = .258); median absolute error, 0.32 (interquartile range [IQR], 0.17, 0.67) versus 0.28 (IQR, 0.13, 0.54) (P = .297). Subgroup analysis also did not show significant differences between the 2 groups (all P > .05). CONCLUSION: The long-term postoperative refractive outcomes of phacotrabeculectomy and phacoemulsification alone were not significantly different in eyes with OAG, regardless of preoperative AL.

Keratoprosthesis Decentration and Tilt Results in Degradation in Image Quality.

PURPOSE: To study the effect of decentration and tilt of the type I Boston keratoprosthesis (KPro) on image quality in both aphakic and pseudophakic eyes. METHODS: An optical ray-tracing program was used to simulate the image projected onto the retina in an eye with a perfectly centered KPro, and in eyes with varying degrees of KPro decentration and tilt. Decentration was modeled along a typical white-to-white distance of 12.0 mm, and the corresponding tilt was calculated assuming a radius of curvature of 8.0 mm, the radius of curvature of the backplate of the KPro. Both aphakic and pseudophakic eyes were simulated, and the corresponding modulation transfer function curves, point spread functions, and astigmatism were analyzed. RESULTS: The perfectly centered KPro produced a high-quality image with no induced astigmatism. Increasing decentration beyond approximately 0.5 mm resulted in poorer image quality with a more pronounced effect in the presence of an intraocular lens. Using models of the normal eye as a threshold, image degradation due to decentration becomes clinically significant at approximately 1.4 mm and 0.9 mm for the aphakic and pseudophakic cases, respectively. Astigmatism introduced by decentration is approximately 0.25 D cylinders at those thresholds. CONCLUSIONS: Decentration of up to 0.5 mm had no significant impact on image quality and an attempt at good intraoperative centration of the KPro within this range is important. Conversely, decentration of 0.9 mm or more during surgical implantation can result in significant degradation in retinal image quality including astigmatism. The effect is greater in the pseudophakic eye.

Evaluation of the Accuracy of Two Marking Methods and the Novel toriCAM Application for Toric Intraocular Lens Alignment.

PURPOSE: To compare the accuracy of two common reference marking methods for toric intraocular lens alignment before and after using the novel toriCAM application. METHODS: In this prospective, randomized study, 22 participants were randomly allocated to two groups, either freehand or slit-lamp-assisted marking. Corneal markings at 0° and 180° were made using either method. The toriCAM application on a smartphone was then used to assess the rotational alignment of these markings and compared to the actual alignment as measured by the Zaldivar calipers on the iTrace Topographer (Tracey Technologies, Houston, TX) as a reference. The errors in marking with and without using the application were analyzed for all patients in each cohort and determined for each marking method. RESULTS: Twenty eyes of 11 patients were marked using the freehand method and 20 eyes of the other 11 patients were marked using the slit-lamp method. The mean absolute error of all markings before toriCAM adjustment was 3.18° ± 2.22°. This was significantly reduced to 1.28° ± 1.34° after using the application (P < .001). This improvement was also noted separately in the freehand and slit-lamp groups. Comparison of the freehand and slit-lamp methods did not show any statistically significant difference in accuracy at both time points. CONCLUSIONS: The novel toriCAM application is able to significantly improve the accuracy of reference marking for both freehand and slit-lamp methods. [J Refract Surg. 2018;34(3):150-155.].

Circular-circular regression model with a spike at zero.

With reference to a real data on cataract surgery, we discuss the problem of zero-inflated circular-circular regression when both covariate and response are circular random variables and a large proportion of the responses are zeros. The regression model is proposed, and the estimation procedure for the parameters is discussed. Some relevant test procedures are also suggested. Simulation studies and real data analysis are performed to illustrate the applicability of the model.

Comparative analysis of coaxial phacoemulsification with 2.2- and 2.8-mm clear corneal incisions.

PURPOSE: To compare the intraoperative efficiency and postoperative visual outcome of coaxial phacoemulsification using 2.2- and 2.8-mm clear corneal incision coaxial phacoemulsification. SETTING: The study was conducted at Vardhaman Mahavir Medical College and Safdarjung Hospital, New Delhi which is a tertiary health care centre. STUDY DESIGN: This is a prospective, randomized, comparative interventional study. MATERIALS AND METHODS: A total of 140 eyes of patients undergoing cataract surgery were enrolled according to the inclusion-exclusion criteria and randomly divided in two groups of 70 such that Group I-Patients underwent phacoemulsification through 2.8-mm clear corneal incision. Group II-Patients underwent phacoemulsification through 2.2-mm clear corneal incision.Postoperative assessment was done at 1 day, 1 and 6 weeks to note best-corrected visual acuity (BCVA), ophthalmic examination, corneal topography, central corneal thickness and corneal endothelial cell count. STATISTICS: 1. Quantitative variables were compared using Mann-Whitney test and Wilcoxon ranked-sum test. 2. Qualitative variables were compared using Fisher's exact test. p value of <0.05 was considered statistically significant. RESULTS: There is steady trend in decrease in postoperative astigmatism with time, more so in 2.8 mm group; however, differences were not found to be statistically significant. 2.2 mm group had larger increase in CCT and ECC compared to 2.8 mm group which was not statistically significant (p = 0.296). CONCLUSION: Reducing the incision size from 2.8 to 2.2 mm does not result in any significant reduction in the amount of surgically induced astigmatism. Also, both the incision sizes have similar intraoperative efficacy when compared in terms of postoperative decrease in corneal endothelial cell count and increase in central corneal thickness.

Violet Light Transmission is Related to Myopia Progression in Adult High Myopia.

Myopia is increasing worldwide. Although the exact etiology of myopia is unknown, outdoor activity is one of the most important environmental factors for myopia control. We previously reported that violet light (VL, 360-400 nm wavelength), which is abundant in the outdoor environment, suppressed myopia progression for individuals under 20 years of age. However, whether VL is also effective for adult high myopia, which can be sight-threatening, has remained unknown. To investigate the influence of VL for adult myopia, we retrospectively compared the myopic progression and the axial length elongation over five years in adult high myopic patients over 25 years of age after two types (non-VL transmitting and VL transmitting) of phakic intraocular lens (pIOL) implantation. We found that high myopic patients with the non-VL transmitting pIOLs implanted are almost two times more myopic in the change of refraction and four times longer in the change of axial length, compared to those implanted with the VL transmitting pIOLs. This result indicated that the VL transmitting pIOL suppressed myopia progression and axial length elongation compared with the non-VL transmitting one. In conclusion, our study showed the VL possibly has an anti-myopia effect for human adults with high myopia.

[Prevalence and age-related changes of corneal astigmatism in patients before cataract surgery]. / Prävalenz und Altersabhängigkeit von kornealem Astigmatismus bei Patienten vor Kataraktchirurgie.

BACKGROUND: The aim of this study was to determine the extent and the distribution of corneal astigmatism in patients awaiting cataract surgery in a mid-European tertiary clinic centre and hence to establish the demand for methods reducing corneal astigmatism. PATIENTS AND METHODS: Keratometry measurements of cataract surgery candidates assigned to a university clinic between January 2013 and October 2014 were recorded and analysed retrospectively. RESULTS: A total of 6900 eyes of 3450 patients with a mean age of 72.5 ± 12.2 were analyzed. The corneal astigmatism was more than 0.5 dioptres (D) in 5193 eyes (75.3 %), >1.0 D in 2641 eyes (38.3 %), >1.5 D in 1304 eyes (18.9 %), >2.0 D in 644 eyes (9.3 %), >2.5 D in 363 eyes (5.3 %), >3.0 D in 236 eyes (3.4 %) and >3.5 D in 149 eyes (2.2 %). With increasing age a shift from with-the-rule astigmatism towards against-the-rule astigmatism was observed. CONCLUSION: Of the patients admitted for routine cataract surgery at our clinic, 2641 eyes (38.3 %) had an astigmatism greater than 1.0 D. Our data could be helpful in establishing a protocol for using toric intraocular lenses and to determine the costs.

Corneal higher-order aberrations after phacoemulsification: a comparison of 3 different incision sizes.

PURPOSE: To analyze the impact of different incision sizes for phacoemulsification on corneal higher-order aberrations (HOA). METHODS: Patients seeking cataract surgery were randomly assigned to one of the following groups: 1.4 mm with biaxial microincision phacoemulsification (25 eyes), 1.8 mm with coaxial phacoemulsification (27 eyes), and 2.2 mm with coaxial phacoemulsification (62 eyes). Inclusion criteria were a minimum age of 18 years and uncomplicated cataract. Exclusion criteria were history of ocular trauma or intraocular surgery, any sign of inflammation or infection, pseudoexfoliation syndrome, glaucoma, optic atrophy, diabetic retinopathy, lens dislocation, cataracta intumescens, cataracta matura, and corneal diseases. Patients underwent phacoemulsification with implantation of an intraocular lens. Aberrometry was performed using an iTrace aberrometer with a pupil scan size of 5.0 mm preoperatively and at postoperative follow-up visits after 1 month. The paired sample t test and analysis of covariance were used for statistical analysis. RESULTS: Ninety patients (114 eyes) were enrolled (mean age 73.7 ± 8.9 years). In all groups, an increase of total HOAs could be measured. The strongest increase was seen in the 2.2 mm group (mean difference 0.031 [95% confidence interval (CI) 0.006-0.056], p = 0.014) and in the 1.4 mm group (mean difference 0.035 [95% CI -0.007 to 0078], p = 0.097). No important difference was found in the 1.8 mm group. CONCLUSIONS: The 2.2 mm and the 1.4 mm incisions seem to have a higher impact on corneal HOAs in comparison to the 1.8 mm incision.

Trabeculectomy With Moorfields Conjunctival Closure Technique Offers Safety Without Astigmatism Induction.

PURPOSE: To evaluate the safety profile and possible change in corneal astigmatism following trabeculectomy with a fornix-based conjunctival flap which is closed with 4 corneal groove-embedded sutures. MATERIALS AND METHODS: Patients scheduled for a primary trabeculectomy were included in this single center, prospective trial between February and April 2013. Refractive status was assessed with an automated refractokeratometer preoperatively and at months 1, 3, 6, and 18 postoperatively, together with clinical assessment of intraocular pressure, visual acuity, postoperative complications, and medication use. Preoperative and postoperative variables were compared using paired samples t tests and vector analysis for corneal astigmatism change was performed. RESULTS: Forty-four eyes of 44 patients were included. Vector analysis showed a transient significant with-the-rule shift in astigmatism without influence on spherical equivalent. Visual acuity was transiently reduced in the first month but recovered to preoperative values with no need to change optical correction. Two patients developed postoperative wound leakage, which was successfully treated with a bandage corneoscleral contact lens. CONCLUSIONS: Trabeculectomy with a fornix-based conjunctival flap closed by 4 corneal groove-embedded sutures results in a low complication rate. This safe suturing technique induces a transient shift of with-the-rule astigmatism, reverting to the preoperative values within 3 months of surgery. Adjustments to refractive correction are recommended to be postponed until after this period.

Donor cross-linking for keratoplasty: a laboratory evaluation.

PURPOSE: This laboratory-based investigation compares the topographic outcomes of conventional penetrating keratoplasty with that of a novel procedure in which donor corneas are cross-linked prior to keratoplasty. METHODS: Penetrating keratoplasty procedures with continuous running sutures were carried out in a porcine whole globe model. Sixty eyes were randomly paired as 'donor' and 'host' tissue before being assigned to one of two groups. In the cross-linked group, donor corneas underwent riboflavin/UVA cross-linking prior to being trephined and sutured to untreated hosts. In the conventional keratoplasty group, both host and donor corneas remained untreated prior to keratoplasty. Topographic and corneal wavefront measurements were performed following surgery, and technical aspects of the procedure evaluated. RESULTS: Mean keratometric astigmatism was significantly lower in the cross-linked donor group at 3.67D (SD 1.8 D), vs. 8.43 D (SD 2.4 D) in the conventional keratoplasty group (p < 0.005). Mean wavefront astigmatism was also significantly reduced in the cross-linked donor group 4.71 D (SD 2.1) vs. 8.29D (SD 3.6) in the conventional keratoplasty group (p < 0.005). Mean RMS higher order aberration was significantly lower in the cross-linked donor group at 1.79 um (SD 0.98), vs. 3.05 um (SD 1.9) in the conventional keratoplasty group (P = 0.02). Qualitative analysis revealed less tissue distortion at the graft-host junction in the cross-linked group. CONCLUSION: Cross-linking of donor corneas prior to keratoplasty reduces intraoperative induced astigmatism and aberrations in an animal model. Further studies are indicated to evaluate the implications of this potential modification of keratoplasty surgery.

Endothelial keratoplasty combined with cataract surgery or alone using polyethylene glycol hydrogel sealant for closure of corneal incisions.

UNLABELLED: We present a surgical technique in which polyethylene glycol hydrogel is used to seal corneal incisions and maintain air in the anterior chamber. This technique was used in 11 eyes that had Descemet-stripping endothelial keratoplasty (DSEK). In 2 cases, DSEK was combined with cataract extraction and intraocular lens implantation. In all cases, the anterior chamber was well formed with no leakage and the donor graft remained attached following surgery. The use of polyethylene glycol hydrogel in DSEK and combined DSEK-cataract surgery may shorten surgery, decrease suture-induced corneal astigmatism, and prevent the need for suture removal. FINANCIAL DISCLOSURE: Neither author has a financial or proprietary interest in any material or method mentioned.

Microincisions in cataract surgery.

UNLABELLED: Improvements in phacoemulsification technology and instrumentation and intraocular lens materials and design have enabled cataract surgery to be performed through incisions smaller than 2.0 mm in external width. This evolution has occurred over time, with new challenges arising at each step of the decrease in incision size. This article reviews the current trend of using increasingly smaller incisions to perform phacoemulsification. Specifically, each facet of phacoemulsification is briefly reviewed from a historical context and then evaluated predominantly from a current perspective to better understand the development of the microincision in cataract surgery. The goal is to help the operating surgeon recognize the potential benefits as well as the potential weaknesses of the smaller incision. FINANCIAL DISCLOSURES: Proprietary or commercial disclosures are listed after the references.

A new approach based on Machine Learning for predicting corneal curvature (K1) and astigmatism in patients with keratoconus after intracorneal ring implantation.

Keratoconus (KC) is the most common type of corneal ectasia. A corneal transplantation was the treatment of choice until the last decade. However, intra-corneal ring implantation has become more and more common, and it is commonly used to treat KC thus avoiding a corneal transplantation. This work proposes a new approach based on Machine Learning to predict the vision gain of KC patients after ring implantation. That vision gain is assessed by means of the corneal curvature and the astigmatism. Different models were proposed; the best results were achieved by an artificial neural network based on the Multilayer Perceptron. The error provided by the best model was 0.97D of corneal curvature and 0.93D of astigmatism.