Accuracy of New Generation Intraocular Lens Calculation Formulas in Vitrectomized Eyes

Challenges and outcomes of cataract surgery after vitrectomy

PURPOSE OF REVIEW

This review examines the challenges and outcomes of cataract surgery after pars plana vitrectomy (PPV), focusing on surgical techniques, timing, and complication management.

RECENT FINDINGS

Cataract formation remains the primary complication post-PPV, affecting approximately 80-100% of patients within two years. Nuclear sclerotic cataracts are most common, occurring in 60-100% of patients over 50, followed by posterior subcapsular cataracts (4-34%), which primarily affect younger and diabetic patients. PPV disrupts the normal oxygen gradient in the vitreous, resulting in a more uniform oxygen distribution and accelerating cataract formation.Post-PPV eyes present unique surgical challenges due to anatomical alterations, including zonular instability and capsular changes characterized by increased fragility, the potential for tears, and altered elasticity. Newer intraocular lens power calculations show promise, but unexpected refractive outcomes may occur. The choice between combined phacovitrectomy and sequential surgeries remains debated, with patient-specific factors guiding the approach. Visual outcomes vary depending on preexisting vitreoretinal pathologies and baseline vision before PPV. Further randomized controlled trials are needed to establish treatment guidelines and improve predictive models.

SUMMARY

Post-PPV cataract surgery presents unique challenges, including anatomical alterations and an increased risk of capsular complications. These necessitate careful consideration of the surgical approach and highlight the need for further research to optimize outcomes and establish treatment guidelines.

Refractive Outcomes After Cataract Surgery-The Impact of Preoperative Visual Acuity, the Intraocular Lens Model, and the Surgeon's Experience: An Empirical Analysis of Hungarian and Kosovan Patients

Background/Objectives: Phacoemulsification and intraocular lens (IOL) implantation comprise a standard procedure for cataract treatment. However, minimal refractive error remains a determinant of postoperative results. Our study aimed to evaluate the refractive outcomes and the impact of the surgeon's experience and the IOL model on Kosovan and Hungarian patients after cataract surgery. Methods: This study included the preoperative and postoperative data of 1417 patients scheduled to undergo cataract surgery with IOL implantation at two centers: the Ophthalmology Department of Semmelweis University, Budapest, Hungary, and the Ophthalmology Department of the University Clinical Center of Kosovo, Prishtina, Kosovo. STATA and SPSS were used for statistical analysis. Results: The data of 1001 Hungarian and 416 Kosovan patients were included in this study. There was a statistically significant difference between the groups in the 1-month postoperative best-corrected distance visual acuity (BCDVA) (p = 0.001); in the Hungarian patients, the 1-month BCDVA was 85.2%, while in the Kosovan patients, it was 49.6%. Of the 14 different IOLs implanted in the Hungarian patients, the AcrySof IQ toric SN6AT, FineVision HP (POD F GF), and 677MTY IOLs resulted in a statistically significant positive impact on the 1-month postoperative visual acuity (p < 0.05). The AcrySof SA60AT and Akreos ADAPT AO, implanted in the Kosovan patients, had a statistically significant positive impact on the 1-month postoperative visual acuity (p < 0.05). More extensive surgeon experience had a statistically significant positive impact on postoperative outcomes (p < 0.00). Conclusions: Multifocal and toric IOLs showed superiority in terms of postoperative outcomes in our study; therefore, we conclude that greater surgeon experience, the availability of premium IOLs, and appropriate IOL selection have a considerable impact on refractive outcomes after cataract surgery.

The LISA-PPV Formula: An Ensemble Artificial Intelligence-Based Thick Intraocular Lens Calculation Formula for Vitrectomized Eyes

PURPOSE

To investigate the relationship between effective lens position (ELP) and patient characteristics, and to further develop a new intraocular lens (IOL) calculation formula for cataract patients with previous pars plana vitrectomy (PPV).

DESIGN

Cross-sectional study.

METHODS

A total of 2793 age-related cataract patients (group 1) and 915 post-PPV cataract patients (group 2) who underwent phacoemulsification with IOL implantation were included. The ELP of 2 groups was compared and the association between ELP and patient characteristics was further evaluated using standardized multivariate regression coefficients. An ensemble artificial intelligence-based ELP prediction model was developed using a training set of 810 vitrectomized eyes, and a thick-lens IOL formula (LISA-PPV) was constructed and compared with 7 existing formulas on an external multi-center testing set of 105 eyes.

RESULTS

Compared to eyes with age-related cataract, vitrectomized eyes showed a similar ELP distribution (P = .19), but different standardized coefficients of preoperative biometry for ELP. The standardized coefficients also varied with the type of vitreous tamponade, history of scleral buckling, and ciliary sulcus IOL implantation. The LISA-PPV formula showed the lowest mean and median absolute prediction error (MAE: 0.63 D; MedAE: 0.44 D), and the highest percentages of eyes within ±0.5 D of prediction error (57.14%) in the testing dataset.

CONCLUSIONS

The ELP prediction required optimization specifically for vitrectomized eyes based on their biometric and surgical characteristics. The LISA-PPV formula is a useful and accurate tool for determining IOL power in cataract patients with previous PPV (available at http://ppv-iolcalculator.com/).

A Review of Intraocular Lens Power Calculation Formulas Based on Artificial Intelligence

PURPOSE

The proper selection of an intraocular lens power calculation formula is an essential aspect of cataract surgery. This study evaluated the accuracy of artificial intelligence-based formulas.

DESIGN

Systematic review.

METHODS

This review comprises articles evaluating the exactness of artificial intelligence-based formulas published from 2017 to July 2023. The papers were identified by a literature search of various databases (Pubmed/MEDLINE, Google Scholar, Crossref, Cochrane Library, Web of Science, and SciELO) using the terms "IOL formulas", "FullMonte", "Ladas", "Hill-RBF", "PEARL-DGS", "Kane", "Karmona", "Hoffer QST", and "Nallasamy". In total, 25 peer-reviewed articles in English with the maximum sample and the largest number of compared formulas were examined.

RESULTS

The scores of the mean absolute error and percentage of patients within ±0.5 D and ±1.0 D were used to estimate the exactness of the formulas. In most studies the Kane formula obtained the smallest mean absolute error and the highest percentage of patients within ±0.5 D and ±1.0 D. Second place was typically achieved by the PEARL DGS formula. The limitations of the studies were also discussed.

CONCLUSIONS

Kane seems to be the most accurate artificial intelligence-based formula. PEARL DGS also gives very good results. Hoffer QST, Karmona, and Nallasamy are the newest, and need further evaluation.

Intraocular lens power calculation for silicone oil-dependent eyes

Background

Silicone oil tamponade is widely used in vitreoretinal surgery. In some cases, silicone oil may not be extracted for a long time or even permanently and is referred to as silicone oil-dependent eyes. In this study, we aimed to deduce a theoretical formula for calculating intraocular lens power for silicone oil-dependent eyes and compare it with clinical findings.

Methods

A theoretical formula was deduced using strict geometric optical principles and the Gullstrand simplified eye model. The preoperative and postoperative refractive statuses of patients with silicone oil-dependent eyes who underwent intraocular lens implantation were studied (Group A, n = 13). To further test our derived theoretical formula, patients with silicone oil tamponade and first-stage intraocular lens implantation were included (Group B, n = 19). In total, 32 patients (32 eyes) were included in the study.

Results

In group A, the calculated intraocular lens power based on our formula was 24.96 ± 3.29 diopters (D), and the actual refraction of the patients was 24.02 ± 4.14D. In group B, the theoretical intraocular lens power was 23.10 ± 3.08D, and the clinical intraocular lens power was 22.84 ± 3.42D. There was no significant difference between the theoretical and clinical refractive powers, and the intraclass correlation coefficient was 0.771 for group A and 0.811 for group B (both p ≤ 0.001). The mean absolute error for silicone oil-dependent eyes of the formula was 1.66 ± 2.09D. After excluding data for two patients with a flat cornea (corneal refractive power < 42D), the mean absolute error decreased to 0.83 ± 0.62D.

Conclusion

A strong correlation between the theoretical and clinical intraocular lens powers was observed, and the formula we deduced can be used to calculate the intraocular lens power for silicone oil-dependent eyes. This formula will help clinicians select a more appropriate intraocular lens for patients with silicone oil-dependent eyes, especially when the corneal refractive power is ≥42D.

Anterior Segment Biometry in a Caucasian Population with Cataracts

PURPOSE

To investigate biometric factors of the anterior segment of phakic eyes with cataracts.

METHODS

This population-based study included Caucasian patients with cataracts in the University Eye Hospital, Goethe University Frankfurt, Germany. Biometric parameters were measured using the swept-source optical coherence tomography method. Patients were grouped into intermediate stages based on decades of life.

RESULTS

In total, 6289 eyes of 3615 patients (age: 70.67 ± 8.42 years) were included. Age-related reductions in the anterior chamber depth (mean ± standard deviation) decreased from 3.26 ± 0.42 mm (group A: 55-59 years) to 2.94 ± 0.4 mm (group G: 85-89 years), and those in the axial length decreased from 24.37 ± 1.87 mm (group A) to 23.39 ± 1.07 mm (group G). Likewise, the white-to-white distance decreased from 12.12 ± 0.48 mm (group A) to 11.96 ± 0.47 mm (group G). Lens thickness tended to increase accordingly from 4.39 ± 0.36 µm (group A) to 4.9 ± 0.40 µm (group G). A comparison of the eyes showed no detectable lateral difference regarding the biometric parameters between the groups (axial length: p = 0.26, Rosenthal effect size = 0.03; lens thickness: p = 0.12, R = 0.03; anterior chamber depth: p = 0.63, Rosenthal effect size = 0.01). The axial length and anterior chamber depth differed significantly between sexes (r = 0.22, p < 0.0001 and r = 0.16, p < 0.0001, respectively). Multiple regression analysis of the anterior chamber depth as a function of biometry parameters as well as age and sex additionally indicated a positive correlation of anterior chamber depth with white-to-white distance (b = 0.32, p = 10-5), axial length (b = 0.10, p = 10-5), keratometry (b = 0.07, p = 10-5), and lens thickness (b=-0.05, p = 10-5) with a high effect size (Cohen f2=1.866, p = 10-5) and strong multiple correlation coefficient (Rosenthal effect size = 0.80, p = 10-5).

CONCLUSIONS

In the anterior segment, there are age- and sex-dependent changes in biometric parameters. In addition, changes in anterior chamber depth were noted in relation to white-to-white distance, axial length, keratometry, and lens thickness. These data should be considered in lens calculation formulas.

Choice of intraocular lens calculation formula for cataract patients with prior pars plana vitrectomy

PURPOSE

To determine the optimal intraocular lens (IOL) calculation formula for vitrectomized eyes with diverse surgical and biometric characteristics.

SETTING

Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.

DESIGN

Retrospective consecutive case series study.

METHODS

This study included 974 vitrectomized eyes (974 patients) scheduled for phacoemulsification with IOL implantation. 11 formulas were evaluated: Barrett Universal II (BUII), Emmetropia Verifying Optical, Hoffer-QST, Kane, Ladas Super Formula, Pearl-DGS, Radial Basis Function (RBF), Haigis, HofferQ, Holladay1, and SRK/T. Risk factors for prediction error (PE) exceeding 1 diopter (D) were determined using multiple logistic regression. Subgroup analyses were performed based on surgical history and biometric parameters.

RESULTS

The risk of hyperopic PE (>1 D) was higher in patients with silicone oil tamponade (odds ratio [OR], 1.82) and longer axial length (AL) (OR, 1.55), while patients with previous scleral buckling (OR, 2.43) or ciliary sulcus IOL implantation (OR, 6.65) were more susceptible to myopic PE (<-1 D). The Kane formula had the highest overall prediction accuracy, and also the best in silicone oil-filled eyes and the flat cornea subgroup. The BUII and RBF displayed the optimal performance in eyes with previous scleral buckle and steep cornea, respectively. In eyes with an AL ≥ 26 mm, the Holladay1 with the nonlinear version of the Wang-Koch AL adjustment (Holladay1-WKn) showed the lowest absolute PE and highest percentage within ± 1.0 D of PE.

CONCLUSIONS

The Kane achieved the highest overall prediction accuracy in vitrectomized eyes. The optimal formula for eyes with previous scleral buckle, steep cornea, or long AL was BUII, RBF, and Holladay1-WKn, respectively.

A No-History Multi-Formula Approach to Improve the IOL Power Calculation after Laser Refractive Surgery: Preliminary Results

This retrospective comparative study proposes a multi-formula approach by comparing no-history IOL power calculation methods after myopic laser-refractive-surgery (LRS). One-hundred-thirty-two eyes of 132 patients who had myopic-LRS and cataract surgery were examined. ALMA, Barrett True-K (TK), Ferrara, Jin, Kim, Latkany and Shammas methods were evaluated in order to back-calculate refractive prediction error (PE). To eliminate any systematic error, constant optimization through zeroing-out the mean error (ME) was performed for each formula. Median absolute error (MedAE) and percentage of eyes within ±0.50 and ±1.00 diopters (D) of PE were analyzed. PEs were plotted with corresponding mean keratometry (K), axial length (AL), and AL/K ratio; then, different ranges were evaluated. With optimized constants through zeroing-out ME (90 eyes), ALMA was better when K ≤ 38.00 D-AL > 28.00 mm and when 38.00 D < K ≤ 40.00 D-26.50 mm < AL ≤ 29.50 mm; Barrett-TK was better when K ≤ 38.00 D-AL ≤ 26.50 mm and when K > 40.00 D-AL ≤ 28.00 mm or AL > 29.50 mm; and both ALMA and Barrett-TK were better in other ranges. (p < 0.05) Without modified constants (132 eyes), ALMA was better when K > 38.00 D-AL ≤ 29.50 mm and when 36.00 < K ≤ 38.00 D-AL ≤ 26.50 mm; Barrett-TK was better when K ≤ 36.00 D and when K ≤ 38.00 D with AL > 29.50 mm; and both ALMA and Barrett-TK were better in other ranges (p < 0.05). A multi-formula approach, according to different ranges of K and AL, could improve refractive outcomes in post-myopic-LRS eyes.

Flapless and Conjunctiva-Sparing Technique for Transscleral Fixation of Intraocular Lens to Correct Refractive Errors in Eyes without Adequate Capsular Support

Purpose

To evaluate refractive outcomes, intraocular lens (IOL) power calculation, and IOL position following a novel conjunctiva-sparing transscleral fixation technique.

Methods

Forty-one eyes of 40 patients managed with a flapless transscleral-sutured technique were included. Preoperative and postoperative refractive errors (spherical equivalents, SE) were compared. IOL position was assessed on the Scheimpflug images. IOL power was calculated by SRK/T, Holladay 1, and Hoffer Q formulas.

Results

The mean age was 57.39 ± 14.83 years (range: 26 to 79 years), and the mean follow-up was 7.46 ± 6.42 months (range: 1 to 24 months). Surgical indications were aphakia (n = 14), subluxated lenses (n = 3), and IOL dislocation (n = 24). The SE was 4.50 ± 6.38 diopter (D) (range: -3.75 to 13.75 D) preoperatively and -1.68 ± 1.57 D (range: -5.50 to 1.13 D) postoperatively (P < 0.001). The mean tilt angle and decentration were 2.90° ± 1.93° (range: 0.39° to 9.10°) and 0.23 ± 0.19 mm (range: 0.02 to 0.94 mm) vertically, and 1.75° ± 1.41° (range: 0.24° to 7.65°) and 0.18 ± 0.19 mm (range: 0.02 to 1.06 mm) horizontally, which were clinically insignificant. All three IOL formulas produced myopic errors (range: -0.29 to -0.50 D). The SRK/T had the lowest median absolute error (0.55 D), followed by the Holladay 1 (0.70 D) and the Hoffer Q (0.74 D). The three formulas had the same percentage of prediction errors (PEs) within ±0.5 D (43.48%), while the Hoffer Q had the highest percentage of PEs within ±1.0 D (82.61%).

Conclusion

The present technique can serve as an alternative approach for transscleral IOL fixation and refractive correction in eyes with compromised capsular support, ensuring the stability of IOLs and reasonable IOL power calculation accuracy.

Intraocular Lens Calculation Using 8 Formulas in Silicone Oil-Filled Eyes Undergoing Silicone Oil Removal and Phacoemulsification After Retinal Detachment

PURPOSE

To evaluate formulas for intraocular lens (IOL) calculation in silicone oil (SO)-filled eyes.

DESIGN

Retrospective, consecutive case series.

METHODS

We conducted our study at the Department of Ophthalmology, Goethe University, Frankfurt, Germany, and included SO-filled eyes that received SO removal combined with phacoemulsification and IOL implantation. Preoperative assessments included biometry (IOLMaster 700; Carl Zeiss Meditec). To evaluate the measurements, we compared the mean prediction error, and mean and median absolute prediction error of 8 different formulas.

RESULTS

A total of 90 eyes matched our inclusion criteria. The median absolute error was lowest in the Barrett Universal II formula (0.43 diopters [D] ± 0.75) followed by Kane (0.44 D ± 0.75), Hill-radial basis function (0.47 D ± 0.74), Holladay II (0.47 D ± 0.77), Sanders Retzlaff Kraff/theoretical (0.51 D ± 0.74), Holladay I (0.51 D ± 0.76), and Haigis and Hoffer Q (0.52 D ± 0.74 each). Regarding eyes within ±0.5 D Barrett Universal II (57.8%, 52 eyes) performed best, again followed by Kane (56.7%, 51 eyes) and Hill-radial basis function (54.4%, 49 eyes).

CONCLUSION

Using modern formulas for IOL calculation in oil-filled eyes improves predictability but still not as good as in unoperated eyes. This issue is created by the change in refractive index due to the SO fill and therefore a lower precision of axial length measurement and effective lens position prediction.

Accuracy of newer generation intraocular lens power calculation formulas in pediatric cataract patients

PURPOSE

To evaluate the accuracy of newer generation intraocular lens (IOL) power calculation formulas (EVO 2.0 and Kane) with established formulas (Barrett Universal II, Haigis and SRK/T) in pediatric cataract patients.

METHODS

Retrospective study. We enrolled 110 eyes (110 patients) in Eye Hospital of Wenzhou Medical University. All patients underwent uneventful cataract surgery and implanted with posterior chamber IOL in the bag. We calculate the mean prediction errors (PE) and percentage within 1 diopter (D) at 1 month to assess the accuracy, and percentage > 2D was defined as prediction accident. Then, we performed subgroup analysis according to age and axial length (AL).

RESULTS

The mean age and AL were 37.45 ± 23.28 months and 21.16 ± 1.29 mm. The mean PE for all patients was as follows: Barrett (- 0.30), EVO (0.18), Haigis (- 0.74), Kane (- 0.36), and SRK/T (0.58), p < 0.001. In addition, EVO and SRK/T formulas were relatively accurate in patients younger than 24 months and with AL ≤ 21 mm, while EVO got lower prediction accident rate than SRK/T (3/41 vs 8/41, 4/52 vs 5/52). Moreover, Barrett, EVO, and Kane formulas achieved better accuracy and lower prediction accident rate in patients older than 24 months and with AL > 21 mm (both > 51/69 and 43/58, and < 3/69 and 3/58).

CONCLUSIONS

In patients older than 24 months and with AL > 21 mm, Barrett, EVO, and Kane formulas were relatively accurate, while in patients younger than 24 months and with AL ≤ 21 mm, EVO was more accurate, followed by SRK/T formula.

The Postvitrectomy Cataract

To review the recent literature regarding risk factors for cataract formation after vitrectomy, the challenges and management strategies for anterior segment surgeons when facing post-vitrectomy cataract surgery, and the visual outcomes of patients undergoing post-vitrectomy cataract surgery. Cataract surgery after vitrectomy can be safely performed to significantly improve the visual outcome in most post-vitrectomy patients, although final visual acuity is primarily limited by the patient’s underlying vitreoretinal pathology.

Outcomes of combined phacoemulsification/intraocular lens implantation and silicon oil removal

PURPOSE

To evaluate the outcomes and complications of simultaneous silicon oil removal (SOR) and phacoemulsification and intra ocular lens implantation.

METHODS

In this retrospective non-comparative case series, the visual, refractive and anatomical outcomes of patients who underwent combined phacoemulsification/silicone oil removal (5700 centistokes) surgery between 2017 and 2019 in a single center were evaluated.

RESULTS

Forty-four eyes of 44 patients (eighteen males) were included. The mean age of the patients was 51.45 ± 11.59 years. The primary pathology was tractional retinal detachment (TRD) secondary to diabetic retinopathy in 36 eyes and rhegmatogenous retinal detachment (RRD) in 8 eyes. The median time period between silicone oil tamponade and removal was 9 months. There was no statistically significant difference between best corrected visual acuity (-0.14 ± 0.69 LogMAR, p= 0.19) and intraocular pressure (p= 0.26) before and after the surgery. Mean post-operative spherical equivalent (SE) at last visit was 0.36 ± 1.64 which was different from the target refraction (- 0.5D). After cataract/SOR surgery, one eye (2.3%) developed retinal re-detachment in RRD patient. Vitreous hemorrhage occurred in nine eyes (20.5%) which all had TRD as the primary pathology.

CONCLUSION

Combined phacoemulsification, silicone oil and IOL implantation removal surgery seems to be a safe and useful procedure with high success rate and acceptable visual, refractive and anatomical outcomes.

Accuracy of intraocular lens power calculation formulas for eyes with scleral-sutured intraocular lens in congenital ectopia lentis

Purpose

To compare the accuracy of intraocular lens calculation formulas in eyes with congenital ectopia lentis (CEL) that underwent scleral-fixated intraocular lens (IOL) implantation.

Setting

Zhongshan Ophthalmic Center, Guangzhou, China.

Design

Retrospective, consecutive case-series study.

Methods

A total of 158 eyes from 158 patients diagnosed from December 12, 2017 to November 16, 2020 with congenital ectopia lentis and undergoing a lensectomy and a Rayner 920H or 970C model IOL scleral-fixation were retrospectively reviewed. The prediction errors (PEs) of the spherical equivalent of eight formulas, Barrett Universal II (BUII), Emmetropia Verifying Optical (EVO), Haigis, Hoffer Q, Holladay 1, Kane, Hill-Radial Basis Function 3.0 (RBF 3.0) and SRK/T were compared.

Results

For CEL patients with sclera-sutured IOL, all eight formulas yielded myopic PEs without constants optimization. After such optimization, the performance of each formula ranked by median absolute error (MedAE) from lowest to highest in diopter, was SRK/T (0.47), EVO (0.48), Kane (0.52), BUII (0.53), Hoffer Q (0.58), Holladay 1 (0.59), Haigis (0.61), and RBF 3.0 (0.62). The EVO and SRK/T formulas had the highest prediction accuracy concerning the percentage of cases within the +/- 0.50 D range of PE and within +/- 1.00 D range of PE in eyes experienced sclera-sutured IOL surgery, respectively.

Conclusion

All formulas with unoptimized constants produced myopic PEs. After optimization, the SRK/T and EVO formula were the two recommended formulas due to having the lowest MedAE and the highest percentage of PE in the range of +/- 0.50 D for CEL patients with sclera-sutured IOL implantations.

Accuracy of Newer Generation IOL Power Calculation Formulas in Eyes With High Axial Myopia

PURPOSE

To compare the accuracy of the Barrett Universal II, Emmetropia Verifying Optical (EVO), Haigis, Kane, and SRK/T formulas for intraocular lens power calculation in patients with high axial myopia.

METHODS

In this retrospective study, 175 eyes (175 patients) that underwent uneventful cataract surgery were enrolled. According to the axial length (AL), the eyes were divided into long AL (26 ⩽ AL < 28 mm), super long AL (28 ⩽ AL < 30 mm), and extremely long AL (⩾ 30 mm). The mean absolute prediction errors (MAE) 3 months postoperatively and the percentage of eyes within different prediction error were compared, followed by subgroup analysis.

RESULTS

The MAE and percentage of eyes within ±0.50 diopters (D) of the five formulas were as follows: Barrett Universal II (0.342, 74.9%), EVO 2.0 (0.314, 82.3%), Haigis (0.336, 74.9%), Kane (0.318, 78.9%), and SRK/T (0.398, 69.7%) (P = .552 and .071, respectively). Although no significant difference was found among the five formulas in the super and extremely long AL groups (P = .792 and .227, respectively), the EVO 2.0 formula achieved the highest accuracy (88.9%, 72 of 81) in the long AL group (P = .049). Moreover, the accuracy of the EVO 2.0 and Haigis formulas was stable, regardless of AL. The SRK/T formula showed a negative trend in the long and super long AL groups, whereas the Barrett Universal II, Kane, and SRK/T formulas showed positive trends in the extremely long AL group.

CONCLUSIONS

Overall, the EVO 2.0 and Kane formulas achieved better results in patients with high axial myopia, whereas the other three formulas showed slightly poor outcomes. [J Refract Surg. 2021;37(11):754-758.].

Characteristics and Risk Factors of Intraocular Lens Tilt and Decentration of Phacoemulsification After Pars Plana Vitrectomy

Purpose

The purpose of this study was to investigate the characteristics and risk factors of intraocular lens (IOL) tilt and decentration of phacoemulsification after pars plana vitrectomy (PPV) using swept-source optical coherence tomography (SS-OCT).

Methods

One hundred four eyes with prior PPV and 104 eyes without PPV undergoing uneventful cataract surgery were enrolled in this study. IOL tilt and decentration were measured by SS-OCT (CASIA2) 3 months postoperatively.

Results

The mean IOL tilt and decentration were greater in the PPV group (5.36 ± 2.50 degrees and 0.27 ± 0.17 mm, respectively) than in the non-PPV group (4.54 ± 1.46 degrees, P = 0.005; 0.19 ± 0.12 mm, P < 0.001, respectively). Multiple logistic regression showed that silicone oil (SO) tamponade (odds ratio [OR] = 5.659, P = 0.021) and hydrophilic IOL (OR = 5.309, P = 0.022) were associated with IOL tilt over 7 degrees, and diabetes mellitus (DM; OR = 5.544, P = 0.033) was associated with IOL decentration over 0.4 mm. Duration of SO tamponade was positively correlated with IOL tilt (P = 0.014) and decentration (P < 0.001). The internal total higher-order aberration, coma, trefoil, and secondary astigmatism in the PPV group were higher than in the non-PPV group, and positively correlated with IOL tilt (P < 0.05).

Conclusions

Patients with prior vitrectomy had greater IOL tilt and decentration than the non-PPV group. Longer duration of SO tamponade, hydrophilic IOL, as well as DM were the risk factors of greater IOL tilt and decentration in patients with prior PPV.

Translational Relevance

Optically sophisticated designed IOLs should be used cautiously in vitrectomized eyes.

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

Purpose

To 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.

Methods

Patients 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.

Results

Forty-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.

Conclusions

Phacovitrectomy 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.

Accuracy of new-generation intraocular lens calculation formulas in eyes undergoing combined silicone oil removal and cataract surgery

PURPOSE

To compare the performance of new-generation and traditional intraocular lens (IOL) calculation formulas in eyes undergoing combined silicone oil (SO) removal and cataract surgery and to evaluate the prediction accuracy of Wang-Koch (WK) adjustment in SO-filled long eyes.

SETTING

Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.

DESIGN

Retrospective consecutive case-series study.

METHODS

New-generation formulas (Barrett Universal II, Emmetropia Verifying Optical, Kane, and Ladas Super formulas) and traditional formulas (Haigis, Hoffer Q, Holladay 1, and SRK/T formulas) were compared. The performance of WK adjustment was assessed in eyes with axial length more than 26 mm. The median absolute error (MedAE) was the main parameter to evaluate the accuracy of formulas.

RESULTS

A total of 211 participants (211 eyes) who underwent combined SO removal and phacoemulsification with IOL implantation were included. Four new-generation formulas displayed statistically significant lower MedAE (0.32 to 0.35 diopter [D]) and higher percentage of eyes within ±1.00 D of prediction error (85.31% to 87.20%) compared with those of the traditional formulas (MedAE: 0.39 to 0.50 D; ±1.00 D: 81.04% to 81.99%, P < .05). For SO-filled long eyes, all traditional formulas showed hyperopic bias (0.36 to 0.65 D, P < .05), except for Haigis formula (0.28 D, P = .083), and this bias could be corrected by WK adjustment (P > .05). EVO formula displayed the lowest MedAE both in total (0.32 D) and in long eyes (0.33 D).

CONCLUSIONS

New-generation formulas and traditional formulas with WK adjustment showed satisfactory prediction accuracy in eyes undergoing combined SO removal and cataract surgery. EVO formula displayed the highest accuracy.

Topical Review: Causes of Refractive Error After Silicone-oil Removal Combined with Cataract Surgery

SIGNIFICANCE

This review summarizes the main factors of refractive error after silicone oil removal combined with cataract surgery.The post-operative refractive results of silicone oil removal combined with cataract surgery are closely related to the patient's future vision quality. This report summarizes the factors that influence the difference between the actual post-operative refractive power and the pre-operatively predicted refractive power after silicone oil removal combined with cataract surgery, including axial length, anterior chamber depth, silicone oil, commonly used tools for measuring intraocular lens power, and intraocular lens power calculation formulas, among others. The aim of the report is to assist clinical and scientific research on the elimination of refractive error after silicone oil removal combined with cataract surgery.

Refractive Outcomes and Anterior Chamber Depth after Cataract Surgery in Eyes with and without Previous Pars Plana Vitrectomy

Purpose: To compare the differences in refractive outcome and anterior chamber depth (ACD) after phacoemulsification between eyes with and without previous pars plana vitrectomy (PPV).Materials and Methods: Patients who had significant cataracts after PPV were included in the study group, and patients with a matched axial length (AL) who had cataracts without PPV were selected as the control group. The performance of new generation intraocular lens (IOL) power calculation formulas (Barrett Universal II, Kane, Ladas Super formulas), and the traditional formulas (SRK/T, Holladay 1, Hoffer Q, Haigis) with and without the Wang-Koch (WK) AL adjustment were compared between the two groups. The postoperative ACD was measured using the Scheimpflug imaging system with manual correction at least three months after surgery. Results: In total, there were 193 eyes from 193 patients in each group. The mean prediction errors (MEs) of the new generation formulas had no significant systemic bias in the study group; the hyperopic shift was displayed in the traditional formulas for eyes with AL > 26mm. However, the difference of MEs between the two groups among all the formulas were not significant. The absolute prediction error (MAE) and median prediction error (Med AE) in the study group were larger than those in the control group among all the formulas. The postoperative ACD of the study group was deeper but not significant than that of the control group. Conclusions: There was no refractive shift in vitrectomized eyes compared with non-vitrectomized eyes no matter in new generation formulas or traditional vergence formulas. The prediction error among all the formulas in vitrectomized eyes were significantly higher than those in non-vitrectomized eyes. The ACD after phacoemulsification in vitrectomized eyes was not significantly different from non-vitrectomized eyes.

Accuracy of Intraocular Lens Power Calculation in Children With Vitrectomized Eyes Undergoing Cataract Surgery

PURPOSE

To assess the predictability of desired postoperative refractive outcomes using the SRK-II formula for intraocular lens (IOL) power calculation in children undergoing cataract surgery in eyes with a previous pars plana vitrectomy (PPV).

METHODS

In this retrospective study, 68 eyes of 66 children who underwent cataract surgery and IOL implantation in eyes that had previous vitrectomy between January 2008 and December 2017 were included. Data were collected on preoperative and postoperative characteristics. The Mann-Whitney test, Kruskal-Wallis test, and multinominal logistic regression were used for comparing the results.

RESULTS

Absolute prediction error (APE) in the cohort was 1.29 ± 1.13. Desirable refractive outcome with insignificant prediction error of less than 0.50 diopters (D) was found in approximately one-third of the children. Patients were further subdivided by magnitude of APE as ≥ 0.50 to ≤ 1.00 D and > 1.00 D. Age at the time of surgery, axial length, mean keratometry, silicone oil removal, IOL position, scleral buckle, and corneal suture did not affect APE and there was no significant difference between the groups (P > .05).

CONCLUSIONS

The mean APE of the SRK-II formula for IOL power calculation in pediatric eyes that had vitrectomy is comparable to that reported in the literature for routine pediatric cataract surgeries. Factors such as age, axial length, corneal power, IOL position (bag/sulcus), scleral buckle, corneal suture, and silicone oil removal done prior to surgery or along with cataract surgery did not affect the APE. [J Pediatr Ophthalmol Strabismus. 2021;58(2):126-131.].

An Advanced Lens Measurement Approach (ALMA) in post refractive surgery IOL power calculation with unknown preoperative parameters

PURPOSE

To test a new method to calculate the Intraocular Lens (IOL) power, that combines R Factor and ALxK methods, that we called Advance Lens Measurement Approach (ALMA).

DESIGN

Retrospective, Comparative, Observational study.

SETTING

Department of Medicine and Surgery, University of Salerno, Italy.

METHODS

Ninety one eyes of 91 patients previously treated with Photorefractive Keratectomy (PRK) or Laser-Assisted in Situ Keratomileusis (LASIK) that underwent phacoemulsification and IOL implantation in the capsular bag were analyzed. For 68 eyes it was possible to zero out the Mean Errors (ME) for each formula and for selected IOL models, in order to eliminate the bias of the lens factor (A-Costant). Main outcome, measured in this study, was the median absolute error (MedAE) of the refraction prediction.

RESULTS

In the sample with ME zeroed (68 eyes) both R Factor and ALxK methods resulted in MedAE of 0.67 D. For R Factor 33 eyes (48.53%) reported a refractive error <0.5D, and 53 eyes (77.94%) reported a refractive error <1D, For ALxK method, 32 eyes (47.06%) reported a refractive error <0.5 D, and 53 eyes (77.94%) reported a refractive error <1 D. ALMA method, reported a MedAE of 0.55 D, and an higher number of patients with a refractive error <0.5 D (35 eyes, 51.47%), and with a refractive error <1 D (54 eyes, 79.41%).

CONCLUSIONS

Based on the results obtained from this study, ALMA method can improve R Factor and ALxK methods. This improvement is confirmed both by zeroing the mean error and without zeroing it.