Prevention and management of refractive prediction errors following cataract surgery

Assessing the interchangeability of keratometry measurements from four biometric devices in intraocular lens power calculations: insights into the predictive accuracy of five modern IOL formulas

BACKGROUND

Achieving accurate intraocular lens (IOL) power calculation is crucial for successful refractive outcomes in cataract surgery. This study aimed to evaluate the interchangeability of keratometry (K) values obtained from four biometric devices (IOLMaster 700, CASIA2, Pentacam, and iTrace) and assess the predictive accuracy of five modern IOL calculation formulas (Barrett Universal II, Cooke K6, EVO 2.0, Kane, and PEARL-DGS) when using K values from these different devices.

METHODS

This prospective study included K values obtained from four biometric devices for use in five IOL power calculation formulas. Predictive accuracy was assessed using multiple statistical parameters, including standard deviation (SD), mean absolute error (MAE), median absolute error (MedAE) and root mean square absolute error (RMSAE). The interchangeability of devices was evaluated by comparing predictive outcomes across devices and formulas, with statistical analyses focusing on consistency and agreement.

RESULTS

Predictive accuracy across the five IOL formulas was stable and showed no statistically significant differences when using keratometry measurements from the same biometric device. However, significant variability was noted when comparing K values from different devices using the same formula. The SS-OCT-based devices (IOLMaster 700 and CASIA2) showed higher consistency in predictive accuracy compared to Scheimpflug-based Pentacam and ray-tracing-based iTrace. Despite this inter-device variability, all five IOL formulas showed overall robust performance across different devices.

CONCLUSIONS

Our findings indicate that keratometry measurements from different biometric devices are not fully interchangeable. SS-OCT-based devices (IOLMaster 700 and CASIA2) provided superior consistency in refractive prediction accuracy. Therefore, clinicians should carefully select biometric device-formula combinations based on the specific measurement principles and desired refractive outcomes. Further research involving larger sample sizes, additional IOL types and biometric devices, as well as assessment of surgeon-related factors, is warranted to optimize refractive accuracy in cataract surgery.

Comparison of Traditional and AI-Based Methods: Barrett Universal II vs. Ladas Super Formula in IOL Power Calculation

Background: Pursuing optimal visual outcomes following cataract surgery remains a cornerstone of modern ophthalmology. Central to this objective is the precise calculation of intraocular lens power. However, despite significant advancements in biometric measurements and computational algorithms, variability in refractive outcomes continues to pose a challenge. This study aims to analyze the outcomes comprehensively by reviewing established and newer techniques. Methods: The eyes included in this study were evaluated based on various criteria, and a total of 210 eyes which met these criteria were included in the research. Our study is a retrospectively designed observational research study. The study included individuals who had experienced successful IOL implantation to correct refractive errors or cataracts. The ARGOS SS-OCT device, a spectral-domain optical coherence tomography system, was used in this study. In measuring the lens power, values were obtained using the Barrett Universal II and Ladas Super Formulas. These values were compared. Postoperative assessments were conducted at 1-3 months and 3-12 months, including spherical equivalents. Results: The mean age of the participants was 63.44 ± 11.62 years. The study's two most frequently used lens brands were ALCON and ZEISS. The lens powers calculated using the Barrett Universal II and Ladas Super Formulas were compared. The mean values calculated using both formulas were highly similar, with no statistically significant differences observed. We compared the spherical equivalent values calculated during the participants' first and second postoperative follow-ups. The spherical equivalent values were similar, with no statistically significant differences. Conclusions: Formulas represent significant advances in ophthalmology and significantly improve visual outcomes; however, differences in their methodology and predictive accuracy warrant further analysis.

Accuracy of intraocular lens power calculation formulae for the Yamane technique of secondary fixation: a systematic review and meta-analysis

OBJECTIVE

This systematic review and meta-analysis aims to assess the refractive outcomes of the Yamane technique for intrascleral fixation of intraocular lenses (SF-IOL) and compare the predictive ability of the various intraocular lens power calculation formulae commonly used in conjunction with the technique.

METHODS

A literature search was conducted in the Medline, Scopus, and Cochrane Library databases for articles published from January 2014 to May 2023. Studies that met the predetermined inclusion criteria were included and subjected to analysis. The primary outcome evaluated was the refractive predictive error, defined as the difference between predicted refraction and post-operative manifest refraction.

RESULTS

Eleven studies met the inclusion criteria, with a cumulative sample size of 615 patients (mean age: 66.6 years). Various IOL formulae were used, with SRK/T being the most frequently adopted formula. The overall mean refractive predictive error for all formulae combined was -0.02 D, which was not statistically significant (p = 0.99). Subgroup analysis for individual formulae also showed no significant difference from predicted error for any formula (p > 0.05).

CONCLUSION

The Yamane technique for SF-IOL shows promising refractive outcomes, and the choice of IOL power calculation formula should be tailored based on patient characteristics and surgeon preference. No formula demonstrated superior predictive ability over others. Further research is needed to develop formulae specifically for eyes with secondary aphakia and poor capsular support.

Spatial and morphologic features of lenses with different axial lengths in cataract patients: a swept-source optical coherence tomography-based study

BACKGROUND

To investigate the spatial and morphologic features of lenses with different axial length (ALs) in cataract patients using swept-source optical coherence tomography (SS-OCT).

METHODS

Totally 105 eyes of 105 patients scheduled to have cataract surgery were included. Eyes were divided into the control (AL < 24.5 mm), moderate myopia (MM, 24.5 ≤ AL < 26 mm) and high myopia (HM, AL ≥ 26 mm) groups. Spatial features including lens vault (LV) and iris-to-lens distance (ILD), and morphologic features including radii of curvature of anterior and posterior surface (Ra, Rp), lens diameter (LD) and lens thickness (LT) were measured in eight directions by SS-OCT.

RESULTS

Spatially, the HM group had larger LV and ILD than the control group (both P < .05). LV and ILD were negatively correlated with AL, respectively (LV: r = -.484, P < .0001; ILD: r = -.656, P < .0001). Morphologically, both MM and HM groups had greater Ra and Rp than the control group. Ra was positively correlated with AL (r = .622, P < .0001), while the relationship between Rp and AL was non-linear. Moreover, the MM and HM groups had larger LD than the control group (both P < .001). Anterior LT was thinner in the HM than in the MM group (P = .026), while posterior LT between these two groups was similar. When compared in eight directions, similar trends were seen in Ra, Rp and LD, and the HM group showed a greater difference in Ra between horizontal and vertical directions.

CONCLUSIONS

This SS-OCT-based study showed that longer axial length is associated with a flatter lens, which was mainly attributed to the increase of Ra and LD. Longitudinal studies would be necessary to establish a causal relationship and temporal progression.

Effect of upper eyelid blepharoplasty with or without orbicularis oculi muscle removal on anterior segment parameters, keratometry, and ocular biometry

PURPOSE

To evaluate the effect of upper eyelid blepharoplasty with or without the removal of a strip of orbicularis oculi muscle on corneal topographic parameters, anterior segment parameters, intraocular pressure, and ocular biometry.

METHOD

This prospective study examined 428 eyes of 214 patients with dermatochalasis. Patients were divided into two groups randomly: those who underwent orbicularis oculi muscle excision (Group 1) during blepharoplasty and those who did not (Group 2). Following a detailed ophthalmological examination, corneal topography was used to evaluate the eyes anterior chamber depth (ACD), iridocorneal angle (ICA), keratometry measurements, and corneal astigmatism (CA) in the preoperative and postoperative first and third months. Ocular biometry was used to assess axial length (AXL) and intraocular lens (IOL) power. Goldmann applanation tonometry was used to measure intraocular pressure (IOP).

RESULTS

The age and gender distribution between the groups were similar (p = 0.595 and p = 0.493, respectively). In Group 1, the mean steep keratometry (K2) value increased by 1.1 D and the mean CA increased by 0.81 D in the first month (p < 0.001 for both comparisons). The increases in K2 and CA were 0.7 D and 0.63 D, respectively, in Group 2 (p < 0.001 and p = 0.004, respectively). At the postoperative third month, both groups demonstrated statistically significant persistent elevations in K2 and CA values (p < 0.05 for all comparisons) compared to preoperative measurements. Group 1 exhibited statistically significant decreases in both IOL power calculations (0.43 D according to the Barrett formula and 0.40 D according to the SRK/T formula, p < 0.001, for both) and ICA (38.1 ± 4.7° vs. 35.8 ± 4.1°, p = 0.009) measurements at the only one-month postoperative follow-up. IOP, AXL, and ACD measurements did not exhibit any significant changes in both groups at the first and third postoperative months.

CONCLUSION

In addition to changes in keratometry and CA, blepharoplasty with muscle excision significantly decreased IOL power and ICA. It may be beneficial to inquire about recent blepharoplasty history and the surgical technique employed in patients scheduled for cataract or refractive surgery.

Immersive teaching using virtual reality technology to improve ophthalmic surgical skills for medical postgraduate students

Medical education is primarily based on practical schooling and the accumulation of experience and skills, which is important for the growth and development of young ophthalmic surgeons. However, present learning and refresher methods are constrained by several factors. Nevertheless, virtual reality (VR) technology has considerably contributed to medical training worldwide, providing convenient and practical auxiliary value for the selection of students' sub-majors. Moreover, it offers previously inaccessible surgical step training, scenario simulations, and immersive evaluation exams. This paper outlines the current applications of VR immersive teaching methods for ophthalmic surgery interns.

Effect of residual sphere on uncorrected visual acuity and satisfaction in patients with monofocal and multifocal intraocular lenses

PURPOSE

To assess the effect of residual sphere on vision and satisfaction in pseudophakic patients.

SETTING

Private clinics, United Kingdom.

DESIGN

Retrospective case series.

METHODS

A multivariate model evaluated the effect of 1-month residual sphere on outcomes of pseudophakic patients. Odds ratios (ORs) were calculated to assess the relative risk of not achieving ≥20/20 monocular uncorrected distance visual acuity (UDVA), ≥20/50 uncorrected near visual acuity (UNVA), and not being satisfied with vision. ORs were assessed for residual sphere -1.00 to +1.00 diopter (D) in quarter-diopter steps, using 0.00 D as a reference.

RESULTS

The analysis included 38 828 multifocal and 11 571 monofocal intraocular lenses (IOLs). The residual myopic sphere ≤-0.25 D and hyperopic sphere ≥+0.50 D had a clinically meaningful effect on UDVA. Although monofocal IOLs had an improvement in UNVA with every additional 0.25 D of myopia, the change in ORs with increasing myopia was not significant for multifocal IOLs. The mean improvement in UNVA comparing eyes with 0.00 D and -1.00 D sphere was 0.26 logMAR for monofocal and 0.03 logMAR for multifocal IOLs. Low near-addition IOLs had a slightly higher gain in UNVA with increasing myopia, but the gain was not as substantial as with monofocal IOLs. The effect of ametropia on satisfaction was more pronounced for multifocal IOLs. For every 0.25 D of residual myopia, there was >25% increase in dissatisfied patients.

CONCLUSIONS

Although myopia improved UNVA in eyes with monofocal IOL, multifocal IOLs did not benefit from residual myopia. Multifocal IOL patients desiring distance vision should be targeted closest to emmetropia, even if it means targeting slight hyperopia.

Does the Difference in Axial Length Affect the Refractive Outcome?

Background

The purpose of this study is to compare axial length (AL) and the refractive outcome after phacoemulsification surgery from 2014 to 2019 at Hospital Sultanah Nur Zahirah, Terengganu, Malaysia.

Method

This was a retrospective record review of all cataract patients who met the inclusion criteria and underwent uneventful superior wound phacoemulsification with nontoric intraocular lens (IOL) by a single surgeon from 2014 to 2019. Using optical biometry or immersion technique, the preoperative AL determined solely via the Sanders, Retzlaff and Kraff 2 (SRK2) formula was selected. The postoperative spherical equivalent (SE) at 6 weeks-12 weeks was retrieved. Using Statistical Package for the Social Sciences version 24.0, the mean differences between targeted and actual postoperative SE were analysed based on the AL.

Result

In this study, 490 eyes of 472 patients aged 25 years old-88 years old (mean age 65.72 years old [SD 8.83]) were involved. There were 162 eyes (33%) in Group A (< 23 mm), 189 eyes (39%) in Group B (23.01 mm-24.0 mm) and 139 eyes (28%) in Group C (> 24.0 mm). The mean AL was 23.63 mm (SD 1.19). The mean differences between the targeted and actual postoperative SE were: -0.09 D (SD 0.60) in Group A, -0.07 D (SD 0.53) in Group B and -0.16 D (SD 0.52) in Group C. No significant difference was found between these groups (P = 0.327).

Conclusion

There was no significant difference in the refractive outcome using the SRK2 formula in different ALs after phacoemulsification surgery. Hence, there is no reason to modify or adjust the targeted SE based on AL.

The Significance of Dry Eye Signs on Preoperative Keratometry Measurements in Patients Scheduled for Cataract Surgery

Purpose

The primary objective was to investigate if subjects with dry eyes had increased variability of keratometry measurements prior to cataract surgery compared to subjects with non-dry eyes. Secondary objectives were to determine which separate signs affected keratometry.

Patients and Methods

This study was part of a prospective interventional randomized controlled trial. After dry eye diagnostics were performed (signs only) subjects were divided into sign of dry eye (SDE) positive and negative groups. To investigate variability, we performed two keratometry measurements for each subject with three different optical biometers: Anterion (OCT optical biometer), Eyestar (combined OCT and reflection-based optical biometer), and Lenstar (reflection based-optical biometer).

Results

One hundred and thirty-one subjects were available for analysis. The variability of astigmatism was significantly higher for subjects with hyperosmolarity compared to normal eyes for the Lenstar, as was the percentage of eyes with variability of astigmatism greater than 0.25 D. The percentage of eyes with variability of average K greater than 0.25 D was higher for subjects with non-invasive keratograph break-up time <10 seconds (NIKBUT positive) compared to normal eyes for the Lenstar.

Conclusion

Combined diagnostic criteria (signs only) showed no statistically significant differences for keratometry measurements between SDE positive and negative. Eyes with hyperosmolarity and NIKBUT positive showed statistically higher variability of keratometry measurements compared to normal eyes for Lenstar, but not for the Anterion or Eyestar biometers.

Light adjustable intraocular lenses in cataract surgery: considerations

PURPOSE OF REVIEW

Light adjustable intraocular lens (LAL) is a promising concept in cataract surgery. This review explores considerations for the use of LALs.

RECENT FINDINGS

Through updates, the safety of LALs and light delivery devices have been enhanced, enabling more efficient treatment with lower ultraviolet (UV) energy. Preoperative topography and aberration are essential for understanding indications for LALs. Furthermore, when determining intraocular lens power, it is crucial to factor in potential postoperative myopia or hyperopic adjustments. This is achieved by establishing a proper postimplantation refractive target and considering potential wavefront changes. Postoperative adjustments for defocus and astigmatism have demonstrated excellent outcomes. Monovision strategy by adjustable blended vision of LALs revealed distance vision of 20/20 along with near vision of J2 in 96% of patients. However, the results of clinical studies on postrefractive cataract surgery showed contrasting outcomes at distance, indicating the need for further research results regarding its effectiveness. A new postoperative workflow needs to be designed to enable a systematic follow-up process.

SUMMARY

LALs are safe and demonstrate promising refractive outcomes. To achieve appropriate results, understanding the changes in optical characteristics associated with adjustment and constructing a new postoperative workflow are necessary.

Dry Eye Disease as a Cause of Refractive Errors After Cataract Surgery - A Systematic Review

Dry eye disease (DED) is a multifactorial ocular surface disorder characterized by loss of tear film homeostasis with associated ocular symptoms, like dryness, foreign body sensation, and inflammation. Numerous reports confirm an increase in dry eye symptoms after cataract surgery. DED also significantly disturbs preoperative biometric measurements, mainly by changes in keratometry measurements. The purpose of this study is to evaluate the effect of DED on biometric measurements before cataract surgery and postoperative refractive errors. PubMed database was searched for keywords: cataract surgery, dry eye disease, refractive error, refractive outcomes, keratometry, and biometry. Four clinical studies evaluating the effect of DED on refractive errors were included. In all studies, biometry was performed before and after dry eye treatment, and the mean absolute error was compared. Various substances have been used to treat dry eye, such as cyclosporin A, liftitegrast, and loteprednol. The refractive error was significantly lower after treatment in all studies. The results unanimously indicate that refractive errors can be reduced by proper treatment of DED before cataract surgery.

[Enhancement Options after Lens and Corneal Refractive Surgery]

BACKGROUND

 Modern preoperative diagnostics as well as current surgical techniques allow cataract and refractive surgery to deliver precise refractive results.Occasionally, unsatisfactory refractive and visual results occur despite all the care taken. In these cases, subsequent improvement is required to achieve the best final visual outcome. This article shows the therapeutic options for the treatment of residual refractive errors after lens and corneal refractive surgery.

KEY MESSAGES

 The causes of postoperative refractive errors after refractive laser- or lens-based procedures are very diverse and require extensive workup of the cause as well as an individual solution to achieve the desired result. Before any further surgical intervention, specific complications of the primary procedure as well as concomitant ocular diseases must be excluded or treated. The appropriate enhancement after keratorefractive surgery depends primarily on the type of primary surgery, residual stromal thickness, possible complications from the initial surgery, and the patient's personal preference. For enhancements using surface treatments, such as PRK, the use of mitomycin C is recommended for prophylaxis of haze formation. After lens surgery, for low-grade postoperative refractive errors (spherical and astigmatic), keratorefractive enhancements provide the most accurate results. For higher refractive errors, lens-based procedures can be used, with add-on IOLs being safer and more precise compared with one IOL exchange. Low astigmatisms can be successfully treated with LRI or keratorefractive surgery, but higher astigmatisms should be corrected with an IOL exchange in the early postoperative period and with an add-on IOL in the later postoperative period. IOL explantations should be performed very cautiously, especially in cases of pronounced capsular fibrosis, previous posterior capsulotomy, and existing weakness of the zonular apparatus.

Cataracts

94 million people are blind or visually impaired globally, and cataract is the most common cause of blindness worldwide. However, most cases of blindness are avoidable. Cataract is associated with decreased quality of life and reduced life expectancy. Most cases of cataract occur after birth and share ageing and oxidative stress as primary causes, although several non-modifiable and modifiable risk factors can accelerate cataract formation. In most patients, phacoemulsification with intraocular lens implantation is the preferred treatment and is highly cost-effective. There has been an increase in the use of comprehensive cataract surgical services, including diagnoses, treatment referrals, and rehabilitation. However, global inequity in surgical service quality is still a limitation. Implementation of preoperative risk assessment, risk reduction strategies, and new surgical technologies have made cataract surgery possible at an earlier stage of cataract severity with the expectation of good refractive outcomes. The main challenge is making the service that is currently available to some patients accessible to all by use of universal health coverage.

Enhancement-Optionen nach Linsen- und refraktiver Hornhautchirurgie

Gelegentlich kommt es trotz aller Sorgfalt und präziser Operationstechnik in der Katarakt- und Refraktivchirurgie zu unbefriedigenden refraktiven und visuellen Ergebnissen. In diesen Fällen ist eine nachträgliche Korrektur erforderlich, um das beste endgültige visuelle Ergebnis zu erzielen. Dieser Beitrag zeigt die Möglichkeiten zur Behandlung residualer Refraktionsfehler nach Linsen- und refraktiver Hornhautchirurgie auf.

High prevalence of refractive errors in an elderly population; a public health issue

PURPOSE

To determine the prevalence of myopia and hyperopia and their associated demographic and ocular factors in people 60 years of age and above.

METHODS

The sampling was performed using a multi-stage stratified random cluster sampling method. The complete demographic and case history information were collected through an interview. Then, all participants underwent optometric examinations including measurement of uncorrected and best-corrected visual acuity, objective, and subjective refraction. Myopia and hyperopia were defined as a spherical equivalent (SE) refraction worse than -0.50 diopters (D) and + 0.50 D, respectively.

RESULTS

Three thousand three hundred ten of 3791 invitees participated, and the data of 3263 individuals were analyzed for this report. The mean age of participants was 68.25 ± 6.53 (60 to 97) years, and 1895 (58.1%) of them were female (number of male/female participants = 1368/1895). The prevalence of myopia and hyperopia was 31.65% (95% CI: 29.68 -33.61) and 45.36% (95% CI: 43.36 -47.37), respectively. The prevalence of severe myopia and hyperopia was 1.14% (95% CI: 0.73 -1.55) and 2.27% (95% CI: 1.57 -2.97), respectively. Based on the results of multiple logistic regression, the prevalence of myopia had a statistically significant direct relationship with age (OR: 1.04; p < 0.001), history of glaucoma surgery (OR:2.75; p < 0.001), pseudophakia (OR: 2.27; p < 0.001), axial length (OR:3.05; p < 0.001), and mean keratometry (OR:1.61; p < 0.001). The education level was significantly inversely related to the myopia prevalence. Moreover, a history of glaucoma surgery (OR:0.44; p < 0.001), pseudophakia (OR = 0.15; p < 0.001), axial length (OR:35; p < 0.001) and mean keratometry (OR:0.62; p < 0.001) were significantly inversely related to the prevalence of hyperopia. 19% and 40.02% of myopic and hyperopic patients had complete visual acuity after correction of refractive error, respectively.

CONCLUSION

The prevalence of refractive errors was high in the Iranian elderly population. A large percentage of the elderly still did not have complete visual acuity after the correction of refractive errors indicating the necessity for attention to other ocular diseases in this age group. The history of cataract and glaucoma surgery could be associated with a myopic shift of refractive error.

Lower refractive prediction accuracy of total keratometry using intraocular lens formulas loaded onto a swept-source optical biometer

PURPOSE

To compare refractive outcomes calculated using intraocular lens (IOL) power calculation formulas loaded onto the IOLMaster 700 with the employment of anterior keratometry (K) and total keratometry (TK).

METHODS

A total of 225 eyes of 225 patients underwent uneventful cataract surgery and implantation of a single model of nontoric monofocal IOL by a single surgeon. All eyes underwent preoperative ocular biometric measurements with the IOLMaster 700. Refractive outcomes, including the mean numerical prediction error (MNE); standard deviation (SD); adjusted mean absolute prediction error (MAE); adjusted median absolute prediction error (MedAE); percentages of eyes with adjusted prediction error (PE) within ± 0.25, ± 0.50, ± 0.75, and ± 1.00 diopter; and IOL Formula Performance Index (FPI), were compared between the K-based formula and the TK-based formula of Barrett Universal II (BUII), Haigis, SRK/T, Holladay 2, and Hoffer Q. Axial length (short, medium, and long) subgroup analyses and anterior and posterior keratometry (flat, medium, and steep) subgroup analyses were conducted.

RESULTS

The K-based formula performed better than the TK-based formula in the accuracy of refractive prediction of each IOL calculation formula: BUII-K (FPI 0.690), BUII-TK (0.677), Haigis-K (0.617), Haigis-TK (0.584), SRK/T-K (0.608), SRK/T-TK (0.595), Holladay 2-K (0.419), Holladay 2-TK (0.406), Hoffer Q-K (0.364), and Hoffer Q-TK (0.356). The subgroup analyses of refractive prediction outcomes showed that TK influenced the refractive outcomes in eyes with relatively normal ranges of axial length and anterior keratometry.

CONCLUSIONS

Using TK instead of K leads to lower refractive prediction accuracy of the IOL power calculation formulas loaded on the IOLMaster 700.

Impact of Global Optimization of Lens Constants on Absolute Prediction Error for Final IOL Power Selection When Using Intraoperative Aberrometry

Purpose

To evaluate absolute prediction errors following phacoemulsification with implantation of a multifocal toric intraocular lens (IOL) using intraoperative aberrometry for IOL power selection and to compare findings with the globally optimized and manufacturer’s recommended lens constants and regression coefficients.

Methods

Data from the Optiwave Refractive Analysis (ORA SYSTEM) were analyzed retrospectively. Absolute prediction errors from surgeries performed before and after the first optimization of the manufacturer’s recommended lens constant and non-optimized regression coefficients for the multifocal toric IOL (SND1T3-6) were compared. Optimization was based on outcomes of procedures performed using the ORA SYSTEM and archived in its database (AnalyzOR). Outcome measures included the proportion of eyes with absolute ORA SYSTEM prediction errors ≤0.25 D and ≤0.5 D and the mean and median absolute prediction errors.

Results

The pre-optimization group included 1027 eyes operated on by 184 surgeons, and the optimized group included 419 eyes operated on by 143 surgeons. The proportions of eyes achieving absolute ORA SYSTEM prediction errors ≤0.25 D (52.5% vs 35.0%, p < 0.0001) and ≤0.50 D (83.1% vs 66.2%, p < 0.0001) were significantly higher in the optimized than in the pre-optimization group. The mean ± standard deviation (0.30 ± 0.25 D vs 0.43 ± 0.32 D, p < 0.0001) and median (0.24 D vs 0.36 D, p < 0.0001) absolute ORA SYSTEM prediction errors were significantly lower after than before optimization. Prediction errors following optimization were reduced more in eyes of average than of long and short axial lengths.

Conclusion

Global optimization of the manufacturer’s IOL lens constants and regression coefficients resulted in lower absolute prediction errors when compared with the initial manufacturer labeled lens constants and non-optimized regression coefficients. Reductions in absolute prediction error can result in lower postoperative residual refractive error, which can improve post-operative uncorrected visual acuity and provide the potential for greater patient satisfaction following cataract surgery.

Inverted lens provides reverse geometry solution for post laser vision correction (LVC) corneas

Many patients require optical correction post-laser vision correction (LVC). While mildly irregular corneal topographic patterns or asymmetry can sometimes be treated with conventional soft lenses, often this proves inadequate. This article introduces a novel technique to provide visual improvement and comfort for these patients. An inverted senofilcon A (Acuvue Oasys®, Johnson & Johnson Vision Care) lens (off-label)was inserted on a patient's eyes that reported discomfort with his current soft contact lenses, which provided improved centration as was seen with a slit lamp and high molecular fluorescein through a yellow filter. The patient achieved a visual acuity of 6/6+ in each eye and reported that the vision did not fluctuate. The post-lens tear film decreased to 35micron versus 43micron in the conventional position, as shown in OCT. The patient reported that he wore the lenses 9 hours a day. His Dry Eye Questionnaire-8 (CLDEQ-8) score decreased from 22 to 15 when wearing the lenses in the inverted position. This case demonstrates that post-laser vision correction patients with minimal asymmetric topography within the treated zone requiring refractive correction may be helped using an inverted conventional soft frequent replacement lens.

Refractive enhancements for residual refractive error after cataract surgery

PURPOSE OF REVIEW

Advances in cataract surgery have allowed surgeons to achieve superior refractive outcomes but have also led to higher patient expectations. Despite ever-evolving technology, residual refractive errors still occur. Postcataract refractive enhancements may be required to deliver satisfactory visual outcomes. This review aims to discuss the potential causes of residual refractive errors and the various enhancement modalities to correct them.

RECENT FINDINGS

A thorough preoperative workup to detect and address underlying pathologic causes of impaired vision should be performed prior to enhancement or corrective procedures. Corneal-based procedures are the safest and most accurate methods of correcting mild cases of residual refractive error. Hyperopic, high myopic, and high astigmatic errors are best managed with lens-based enhancements. Piggyback intraocular lenses (IOLs) are safer and more effective compared with IOL exchange. Toric IOL rotation and IOL exchange are ideally performed in the early postoperative period.

SUMMARY

A multitude of options exist for effective correction of residual refractive errors. The choice on how to best manage these patients depends on many factors such as the cause of refractive error, type of IOL used, ocular comorbidities, and patient preference.