Intraocular Lens Power Calculation in Eyes with Previous Excimer Laser Surgery for Myopia: A Report by the American Academy of Ophthalmology

The role of the epithelium in intraocular lens and corneal power calculation

PURPOSE

To investigate the influence of the corneal epithelium on corneal power, particularly in special cases such as post-refractive surgery and keratoconus.

METHODS

A retrospective observational study. Measurement data were obtained from a high-resolution anterior segment analyser (CSO MS-39). Corneal curvature and power data, as well as surface height data, were organised in a cylindrical coordinate system. Calculations considered one, two and three refractive surfaces, examining the role of epithelial thickness and stromal curvature.

RESULTS

The effect of the epithelium on corneal power was minimal (<0.1 D) in normal corneas, but it was considerable in keratoconus and post-refractive surgery cases, with differences up to 0.9 D. The effect decreased for larger measurement zones.

CONCLUSION

Incorporating epithelial thickness and stromal curvature into corneal power calculations is a crucial next step in accurate corneal power and intraocular lens calculation in eyes with previous refractive surgery or keratoconus. This study highlights the need for advanced diagnostic and calculation methods in complex cases.

Visual and Safety Outcomes of Refractive Correction Procedures Following Lens Removal for Residual Refractive Error: A Systematic Review and Meta-analysis

PURPOSE

To evaluate residual refractive errors after intraocular lens (IOL) extraction and the safety and effectiveness of refractive correction procedures.

METHODS

The eligibility criteria for this systematic review were patients who had undergone cataract or clear lens extraction and had experienced residual refractive error. All study designs were considered for inclusion and non-English publications, non-peer reviewed articles, books, and systematic reviews were excluded. A comprehensive electronic search strategy was employed on PubMed, Scopus, Web of Science, Cochrane, and Embase databases from January 1, 1950, to August 1, 2023.

RESULTS

This review examined 55 articles with 2,223 eyes. Piggyback IOL and IOL exchange are highly effective in correcting both myopia and hyperopia, showing significant improvements in spherical and cylindrical errors. Among corneal-based procedures, laser in situ keratomileusis offers a strong balance, with substantial reductions in both spherical and cylindrical errors, along with a favorable safety profile. Small incision lenticule extraction improves uncorrected distance visual acuity (UDVA), particularly in hyperopic patients, whereas photorefractive keratectomy is effective for both UDVA and astigmatism correction, although it has less impact on corrected distance visual acuity (CDVA). Conductive keratoplasty is effective but has greater variability and a higher incidence of complications.

CONCLUSIONS

Significant improvements in spherical equivalent were consistently observed after treatment across the different procedures. Both UDVA and CDVA demonstrated notable enhancements, suggesting an overall efficacy in improving visual function. Although complications were reported, they were generally low in incidence and varied across procedure types. [J Refract Surg. 2025;41(1):e73-e87.].

Clinical History Method versus Corneal Tomographers in Estimating Corneal Power after Photorefractive Surgery

AIMS

To investigate the concordance between the corneal power determined by various approaches with two tomographers (MS-39® and Galilei G6®) and the clinical history method (CHM) in patients undergoing photorefractive surgery with excimer laser for myopic errors.

MATERIAL AND METHODS

Prospective cohort study. Patients undergoing keratorefractive surgery, and having pre- and postoperative keratometries, and tomographies, were included.

RESULTS

In 90 eyes, the differences in the power estimated by the CHM and the one determined by four approaches with the corneal tomographers, which included measurements of the posterior cornea, did not show statistically significant differences in their averages. However, the 95% limits of agreement were very wide. After obtaining regression formulas to adjust the values of these four variables, the results of the agreement analysis were similar.

CONCLUSION

Although certain values either directly determined or derived from measurements with the Galilei® and MS-39®corneal tomographers, approximated the estimated value of postoperative corneal power according to the CHM, due to the amplitude of their limits of agreement, these calculations must be taken with care, because they may not be accurate in a given eye.

Choroidal Thickness and Central Macular Thickness Measurements with Cirrus HD-OCT in Healthy Individuals in the Turkish Population

AIM

This research was conducted to determine the normal values of choroidal thickness in healthy individuals and to evaluate the relationship between this thickness and age, gender, refraction, axial length and average macular thickness using OCT.

MATERIAL AND METHOD

In the study, the right eyes of 400 healthy individuals (234 women, 166 men) between the ages of 4 and 70 years, who applied to the Department of Ophthalmology outpatient clinic for examination, were evaluated.

RESULTS

Macular thickness, macular volume, and foveal thickness were found to be 249.12 ±21.32 µm, 9.98 ±0.5 µm3 and 280 ±13.45 µm, respectively. According to linear regression analysis, a negative correlation was detected between age and subfoveal choroidal thickness (p < 0.05). It was determined that foveal thickness, retinal volume and average retinal thickness were higher in men, and foveal thickness increased with age (p < 0.05).

CONCLUSION

As a result of the research, it was determined that age is an important factor affecting choroidal thickness. It is thought that, in future, improving in vivo imaging of the choroid and measuring choroidal thickness using OCT will facilitate understanding of the pathophysiological basis of many ophthalmological diseases.

Intravitreal Dexamethasone Implant in the Treatment of Diabetic Macular Edema Focusing on the Role of OCT Biomarkers

OBJECTIVE

The aim of this study was to evaluate the outcomes of Ozurdex® (DEX) implant in patients with diabetic macular edema (DME) in real-world clinical practice, and to determine the correlation between known OCT biomarkers and the effect of treatment.

MATERIAL AND METHODS

This retrospective study included 42 eyes of 33 patients (16 women, 17 men) treated with DEX at the Department of Ophthalmology, Faculty of Medicine and Dentistry of Palacký University and University Hospital Olomouc for DME indication between 2020 and 2023. Follow-up examinations were conducted at 1, 3, and 6 months after the first DEX application. The main assessed parameters were: best-corrected visual acuity (BCVA), intraocular pressure (IOP), central retinal thickness (CRT), OCT biomarkers. The results were subsequently statistically evaluated.

RESULTS

At the first follow-up after DEX application, there was an average decrease in CRT of 186 ±146µm and a gain of 3 ±7 letters. Positive morphological and functional responses were observed in 39 eyes (92.9%) and 23 eyes (54.8%) respectively. The disorganization of retinal inner layers (DRIL) biomarker was initially present in 41 eyes (97.6%), with reduction or disappearance observed in 13 eyes (31%) post-application. Eyes with ellipsoid zone disruption (EZ disruption) had an average initial BCVA of 49.6 letters, compared to 57.8 letters in the group without this biomarker. The mean gain in BCVA was +8.7 letters in treatment-naive eyes and +2.1 letters in previously treated eyes. Chronic DME was less frequent in treatment-naive (n = 1, 14.3%) compared to previously treated eyes (n = 28, 84.8%). All these results were statistically significant (p < 0.05). An increase in IOP post-DEX application occurred in 9 patients (21.4%).

CONCLUSION

Our results confirm DEX as a safe and effective treatment option for DME. Treatment-naive patients achieved better functional outcomes. We confirmed ellipsoid zone disruption (EZ disruption) as a negative biomarker. Additionally, we demonstrated the capacity of DEX to reduce disorganization of the retinal inner layers (DRIL).

Accuracy of recent intraocular lens power calculation methods in post-myopic LASIK eyes

This retrospective study compared postoperative prediction errors of recent formulas using standard- or total keratometry (K or TK) for intraocular lens (IOL) power calculation in post-myopic LASIK patients. It included 56 eyes of 56 patients who underwent uncomplicated cataract surgery, with at least 1-month follow-up at Keio University Hospital in Tokyo or Hayashi Eye Hospital in Yokohama, Japan. Prediction errors, absolute errors, and percentage of eyes with prediction errors within ± 0.25 D, ± 0.50 D, and ± 1.00 D were calculated using nine formulas: Barrett True-K, Barrett True-K TK, Haigis-L, Haigis TK, Pearl-DGS, Hoffer QST, Hoffer QST PK, EVO K, and EVO PK. Statistical comparisons utilized Friedman test, Conover's all-pairs post-hoc, Cochran's Q, and McNemar post-hoc testing. Root-Mean-Square Error (RMSE) was compared with heteroscedastic testing. Barrett True-K TK had the lowest median predicted refractive error (-0.01). EVO PK had the smallest median absolute error (0.20). EVO PK had the highest percentage of eyes within ± 0.25 D of the predicted value (58.9%), significantly better than Haigis-L (p = 0.047). EVO PK had the lowest mean RMSE value (0.499). The EVO PK formula yielded the most accurate IOL power calculation in post-myopic LASIK eyes, with TK/PK values enhancing accuracy.

Updating the no-history method in intraocular lens power calculation after myopic laser vision correction

PURPOSE

To describe the Shammas-Cooke formula, an updated no-history (NH) formula for IOL calculation in eyes with prior myopic laser vision correction (M-LVC), and to compare the results with the Shammas PL, Haigis-L, and Barrett True-K NH formulas.

SETTING

Bascom Palmer Eye Institute (BPEI), The Lennar Foundation Medical Center, University of Miami, Miami, Florida; Dean A. McGee Eye Institute (DMEI), University of Oklahoma, Oklahoma City, Oklahoma; and private practice, Lynwood, California, and St Joseph, Michigan.

DESIGN

Retrospective observational study.

METHODS

We analyzed 2 large series of cataractous eyes with prior M-LVC. The training set (BPEI series of 330 eyes) was used to derive the new corneal power conversion equation to be used in the new Shammas-Cooke formula and the testing set (165 eyes of 165 patients in the DMEI series) to compare the updated formula with 3 other M-LVC NH formulas on the ASCRS calculator: Shammas PL, Haigis-L, and Barrett True-K NH.

RESULTS

Mean prediction error was 0.09 ± 0.56 diopters (D), -0.44 ± 0.61 D, -0.47 ± 0.59 D, and -0.18 ± 0.56 D and the mean absolute error was 0.43 D, 0.60 D, 0.61 D, and 0.45 D for the Shammas-Cooke, Shammas PL, Haigis-L, and Barrett True-K NH, respectively. The percentage of eyes within ±0.50 D was 66.7% vs 47.9%, 48.5%, and 65.5%, respectively.

CONCLUSIONS

The Shammas-Cooke formula performed better than the Shammas PL and Haigis-L (P < .001 for both) and as well as the Barrett True-K NH formula (P = .923).

Clinical outcomes of the light-adjustable lens in eyes with a history of prior corneal refractive surgery

PURPOSE

To evaluate the visual and refractive outcomes in eyes with a history of laser corneal refractive surgery implanted with the second-generation light-adjustable lens (LAL).

SETTING

Private practice, Sioux Falls, South Dakota.

DESIGN

Retrospective, consecutive case series.

METHODS

Eyes with a history of prior corneal refractive surgery that underwent cataract surgery with implantation of the LAL and were targeted for plano were included. Data on the type and number of prior refractive surgeries were collected, in addition to the timing and number of postoperative adjustments. The primary outcome measures were uncorrected distance visual acuity (UDVA), corrected distance visual acuity, and the percentage (%) of eyes within ±0.25 diopter (D), ±0.50 D, and ±1.00 D of their refractive target.

RESULTS

76 eyes from 70 patients were included. A total of 45 eyes with a history of 1 prior refractive surgery and 31 eyes with a history of ≥2 refractive surgeries were included. 74% (n = 56) of all eyes achieved UDVA of 20/20 or better, 88% (n = 67) achieved 20/25 UDVA or better, and 93% (n = 71) were correctable to 20/20 or better postoperatively. For refractive outcomes, 66% of eyes (n = 50) were within ±0.25 D and 86% (n = 65) were within ±0.50 D of refractive target.

CONCLUSIONS

Patients with a history of laser corneal refractive surgery achieved favorable visual and refractive outcomes with the LAL. This intraocular lens (IOL), which affords postoperative adjustability, is a promising option for patients with a history of corneal refractive surgery who maintain high expectations for functional uncorrected acuity after cataract surgery.

Lens Factor Choice in IOL Power Calculation after Laser Refractive Surgery: The Right Constant for Advanced Lens Measurement Approach (ALMA)

Background/Objectives: To evaluate the advanced lens measurement approach (ALMA) formula accuracy using different lens constants available on the user group for laser interference biometry (ULIB) and IOL Con platforms. Methods: In this retrospective, comparative, case-series study, 150 eyes of 160 patients with previous myopic Photorefractive Keratectomy (PRK) or laser-assisted in situ keratomileusis (LASIK), who underwent uneventful cataract surgery and IOL implantation, were examined. The ALMA formula was evaluated to calculate the refractive prediction error (PE), analysing four different categories of lens constants: both nominal and optimized A-Constant for SRKT, which are available on the ULIB and IOL Con platforms. An additional analysis was carried out in this study, evaluating if a decreased ULIB optimized constant (DUOC) with different fixed factors (-1.2 -1.3 -1.4 -1.5) could improve refractive outcomes. Median absolute error (MedAE) and percentage of eyes within ±0.50 and ±1.00 diopters (D) of prediction error were measured as the main outcomes. Results: Comparing the lens factors available on ULIB and IOL Con platforms, the ALMA formula reported a lower MedAE and higher percentages of eyes with a refractive PE within 1.0 D using ULIB nominal constants (all p < 0.05). Using DUOC (-1.3), and there was a statistically significant improvement of both MedAE and of the percentages of eyes with PE within ±0.50 D with the ALMA method compared to nominal ULIB constants (all p < 0.05). Conclusions: The impact of different lens factors in the IOL power calculation after myopic LRS should be carefully evaluated. The ALMA formula, in the absence of optimized constants by zeroing the mean error, should be used by subtracting 1.3 from the optimized ULIB constants available on the IOL Con website. This finding suggests further studies to test which of these constants could work better with the other post-refractive surgery formulas.

Effect of Posterior Keratometry and Corneal Radius Ratio on the Accuracy of Intraocular Lens Formulas After Myopic LASIK/PRK

PURPOSE

To investigate the impact of back-to-front corneal radius ratio (B/F ratio) and posterior keratometry (PK) on the accuracy of intraocular lens power calculation formulas in eyes after myopic laser in situ keratomileusis (LASIK)/photorefractive keratectomy (PRK) surgery.

METHODS

A retrospective, consecutive case series study included 101 patients (132 eyes) with cataract after myopic LASIK/PRK. Mean prediction error (PE), mean absolute PE (MAE), median absolute error (MedAE), and the percentage of eyes within ±0.25, ±0.50, and ±1.00 diopters (D) of PE were determined.

RESULTS

The Barrett True K-TK formula exhibited the lowest MAE (0.59 D) and MedAE (0.48 D) and the highest percentage of eyes within ±0.50 D of PE (54.55%) in total. In eyes with a B/F ratio of 0.70 or less and PK of -5.70 D or greater, the Potvin-Hill formula displayed the lowest MAE (0.46 to 0.67 D).

CONCLUSIONS

The Barrett True-TK exhibited the highest prediction accuracy in eyes after myopic LASIK/PRK overall. However, for eyes with a low B/F ratio and flat PK, the Potvin-Hill performed best. [J Refract Surg. 2024;40(9):e635-e644.].

The Development of a Thick-Lens Post-Myopic Laser Vision Correction Intraocular Lens Calculation Formula

PURPOSE

To describe the development of the post-myopic laser vision correction (LVC) version of the PEARL-DGS intraocular lens (IOL) calculation formula and to evaluate its outcomes on an independent test set.

DESIGN

Retrospective, single-center case series.

METHODS

A modified lens position prediction algorithm was designed along with methods to predict the posterior corneal curvature radius and correct the corneal power measurement error. A different set of previously operated eyes that underwent LVC was used to evaluate the prediction precision of the post-LVC formula.

RESULTS

Post-LVC PEARL-DGS formula significantly reduced mean absolute error of prediction in comparison to Haigis-L, Shammas, and American Society of Cataract and Refractive Surgery (ASCRS) average formulas (P < .001). It exhibited similar postoperative refractive precision as the Barrett True-K No History formula (P = .61).

CONCLUSION

The post-LVC formula development process described in this article performed as well as the state-of-the-art post-LVC formula on the present test set. Further studies are required to assess its efficacy in other independent sets.

Cataract Outcomes Following Scleral Buckle Surgery for Retinal Detachment

Purpose

To investigate refractive, visual, and safety outcomes of cataract surgery performed after scleral buckling (SB) for retinal detachment (RD).

Patients and methods

A chart review at an academic medical center identified eyes with history of SB followed by subsequent cataract extraction between 2010 and 2022. Eyes with less than 3 weeks follow-up, silicone oil at time of biometry measurement, previous cornea surgery, or co-existing pathology impacting refractive outcomes were excluded. Predicted postoperative spherical equivalents (SE) were calculated with the Barrett Universal II (BU2), Kane, and SRK/T formulas for the implanted intraocular lens (IOL), and complications occurring within 1 year of surgery were abstracted.

Results

Sixty eyes of 60 patients met criteria for inclusion, and 40 (66.7%) had postoperative refraction recorded. Absolute prediction errors were 0.49, 0.45, and 0.52D with BU2, Kane, and SRK/T, respectively. Actual postoperative refraction was within 0.5 and 1.0 D of predicted in 26 (65.0%) and 36 (90.0%) using BU2, 23 (58%) and 37 (93%) using Kane, and 21 (52.5%) and 36 (90.0%) using SRK/T. In eyes with macula-on RD, corrected distance visual acuity (CDVA) of logMAR 0.301 (≈20/40) and logMAR 0.544 (≈20/70) or better was achieved in 12 (75.0%) and 15 (93.8%) of eyes. For macula-off RD eyes, these proportions were 19 (63.3%) and 24 (80.0%), respectively. Posterior capsular opacification requiring Nd: YAG capsulotomy was the most frequent complication in 30 (56.7%) eyes.

Conclusion

Refractive outcomes of cataract surgery following SB may be modestly reduced, even when using modern formulas. Nevertheless, cataract surgery in this population results in favorable visual outcomes.

Camellin-Calossi Formula for Intraocular Lens Power Calculation in Patients With Previous Myopic Laser Vision Correction

PURPOSE

To assess the performance of the Camellin-Calossi formula in eyes with prior myopic laser vision correction.

METHODS

This was a retrospective case series. Patients included had a history of uncomplicated myopic laser vision correction and cataract surgery. The primary outcome measures were cumulative distribution of absolute refractive prediction error, absolute refractive prediction error, and refractive prediction error. These parameters were estimated post-hoc using the Camellin-Calossi, Shammas, Haigis-L, Barrett True-K with or without history, Masket, and Modified Masket formulas and their averages starting from biometric data, clinical records, postoperative refraction, and intraocular lens power implanted.

RESULTS

Seventy-seven eyes from 77 patients were included. The Camellin-Calossi, Shammas, Haigis-L, Barrett True-K No History, Masket, Modified Masket, and Barrett True-K formulas showed a median absolute refractive error (interquartile range) of 0.25 (0.53), 0.51 (0.56), 0.44 (0.65), 0.45 (0.59), 0.40 (0.61), 0.60 (0.70), and 0.55 (0.76), respectively. The proportion of eyes with an absolute refractive error of ±0.25, 0.50, 0.75, 1.00, 1.50, and 2.00 diopters (D) for the Camellin-Calossi formula was 54.5%, 72.7%, 85.7%, 92.2%, 98.7%, and 100%, respectively. The cumulative distribution of the Camellin-Calossi formula showed the best qualitative performances when compared to the others. A statistically significant difference was identified with all of the others except the Haigis-L using a threshold of 0.25, with the Shammas, Modified Masket, and Barrett True-K at a threshold of 0.50 D and the Barrett True-K and Modified Masket at a threshold of 1.00 D.

CONCLUSIONS

The Camellin-Calossi formula is a valid option for intraocular lens power calculation in eyes with prior myopic laser vision correction. [J Refract Surg. 2024;40(3):e156-e163.].

Accuracy of the PEARL-DGS Formula for Intraocular Lens Power Calculation in Post-Myopic Laser Refractive Corneal Surgery Eyes

PURPOSE

To investigate the accuracy of the PEARL-DGS formula for intraocular lens (IOL) power calculation in post-myopic laser refractive corneal surgery eyes.

DESIGN

Retrospective case series.

METHODS

A total of 139 eyes of 139 patients (mean axial length: 27.4 ± 2.1 mm) who had prior myopic laser refractive corneal surgery and subsequent cataract surgery using Tecnis ZCB00 from March 2018 to February 2023 were included. Refractive outcomes of 5 formulas (Barrett True K, Haigis-L, Hoffer-QST, PEARL-DGS, and Shammas-PL) were evaluated. Prediction error was defined as the difference between the measured and predicted postoperative refractive spherical equivalent using the IOL power actually implanted. Mean prediction error (MPE), median absolute prediction error (MedAE), and mean absolute prediction error were calculated.

RESULTS

Without constant optimization, the PEARL-DGS resulted in a MPE of +0.05 ± 0.65 diopters (D), whereas the other formulas resulted in myopic shifts. The MedAEs of the formulas were 0.39, 0.53, 0.65, 0.85, and 1.11 D for the PEARL-DGS, Hoffer-QST, Barrett True K, Shammas-PL, and Haigis-L, respectively, in order of magnitude (P < .05). With constant optimization, there were no statistically significant differences in the MedAEs among the 5 formulas (P = .388).

CONCLUSIONS

In comparison to other IOL formulas, the PEARL-DGS resulted in better refractive outcomes after cataract surgery in post-myopic laser refractive corneal surgery eyes without constant optimization. We suggest that PEARL-DGS be considered as the first choice for IOL power calculation in these eyes when the clinicians do not have their optimized constants.

An update on intraocular lens power calculations in eyes with previous laser refractive surgery

PURPOSE OF REVIEW

There is an ever-growing body of research regarding intraocular lens (IOL) power calculations following photorefractive keratectomy (PRK), laser-assisted in-situ keratomileusis (LASIK), and small-incision lenticule extraction (SMILE). This review intends to summarize recent data and offer updated recommendations.

RECENT FINDINGS

Postmyopic LASIK/PRK eyes have the best refractive outcomes when multiple methods are averaged, or when Barrett True-K is used. Posthyperopic LASIK/PRK eyes also seem to do best when Barrett True-K is used, but with more variable results. With both aforementioned methods, using measured total corneal power incrementally improves results. For post-SMILE eyes, the first nontheoretical data favors raytracing.

SUMMARY

Refractive outcomes after cataract surgery in eyes with prior laser refractive surgery are less accurate and more variable compared to virgin eyes. Surgeons may simplify their approach to IOL power calculations in postmyopic and posthyperopic LASIK/PRK by using Barrett True-K, and employing measured total corneal power when available. For post-SMILE eyes, ray tracing seems to work well, but lack of accessibility may hamper its adoption.

Cataract surgery following refractive surgery: Principles to achieve optical success and patient satisfaction

A growing number of patients with prior refractive surgery are now presenting for cataract surgery. Surgeons face a number of unique challenges in this patient population that tends to be highly motivated to retain or regain functional uncorrected acuity postoperatively. Primary challenges include recognition of the specific type of prior surgery, use of appropriate intraocular lens (IOL) power calculation formulas, matching IOL style with spherical aberration profile, the recognition of corneal imaging patterns that are and are not compatible with toric and/or presbyopia-correcting lens implantation, and surgical technique modifications, which are particularly relevant in eyes with prior radial keratotomy or phakic IOL implantation. Despite advancements in IOL power formulae, corneal imaging, and IOL options that have improved our ability to achieve targeted postoperative refractive outcomes, accuracy and predictability remain inferior to eyes that undergo cataract surgery without a history of corneal refractive surgery. Thus, preoperative evaluation of patients who will and will not be candidates for postoperative refractive surgical enhancements is also paramount. We provide an overview of the specific challenges in this population and offer evidence-based strategies and considerations for optimizing surgical outcomes.

The tolerance of refractive errors of extended depth of focus intraocular lens in patients with previous corneal refractive surgery

PURPOSE

To evaluate the tolerance for refractive errors and visual outcomes of extended depth of focus intraocular lens (EDOF IOLs) in patients with previous corneal refractive surgery for myopia.

METHODS

Patients from Aier Eye Hospital of Wuhan University with previous myopia excimer laser correction underwent cataract surgery and implantation of an EDOF IOL. The follow-up period was three months. The uncorrected distance, intermediate, and near visual acuities (UDVA, UIVA, UNVA), corrected distance visual acuity (CDVA), spherical equivalent (SE), defocus curve, optical quality, including modulation transfer functions (MTF) and Strehl ratio (SR), National Eye Institute Visual Functioning Questionnaire-14 for Chinese people (VF-14-CN), spectacle independence, and dysphotopsia were assessed.

RESULTS

At the final visit, UDVA, CDVA, UIVA, and UNVA (LogMAR) were 0.06 ± 0.09, 0.01 ± 0.06, 0.11 ± 0.08, 0.20 ± 0.10, respectively. The mean spherical equivalent (SE) was - 0.57 ± 0.58D, sphere and cylinder were - 0.24 ± 0.60D, - 0.70 ± 0.58D respectively. No statistical difference in UDVA between eyes with SE in ± 0.50 D and in ± 1.0 D (p > 0.05). Corneal astigmatism > 1.00D has no significant effect on postoperative visual acuity (p > 0.05). The defocus curve showed that visual acuity could reach 0.2 in the refractive range of + 0.50D ~ - 1.50D. SR and MTF values were all higher than before the surgery. In bilateral implantation patients, the VF-14-CN questionnaire score and visual quality were quite excellent.

CONCLUSION

The EDOF IOL have a certain tolerance for refractive errors and corneal astigmatism, and it's recommended for patients with prior myopia excimer laser surgery to achieve satisfactory visual performance.

Accuracy of new intraocular lens calculation formulas in Chinese eyes with short axial lengths

PURPOSE

To compare the measurement accuracy of new/updated intraocular lens (IOL) power calculation methods, namely, Kane, Emmetropia Verifying Optical (EVO), with existing methods (Barrett Universal II, Olsen, Haigis, Hoffer Q, Holladay 1, SRK/T) in Chinese eyes with axial lengths ≤ 22.5 mm.

METHODS

The study included data from patients who underwent uneventful cataract surgery with the insertion of ZCB00 IOL. Refractive prediction errors were determined by calculating the difference between postoperative refraction and the predicted refraction using each formula. Various parameters were evaluated, including mean prediction error (ME), mean absolute error (MAE), median absolute error (MedAE), and the percentage of eyes with prediction errors (PE) within different ranges.

RESULTS

The study enrolled 38 eyes of 38 patients, and the Barrett Universal II formula demonstrated the lowest MAE and MedAE among the tested formulas. Post hoc analysis using Wilcoxon signed-rank pairwise comparisons for non-parametric samples with Bonferroni correction revealed no significant difference in postoperative refractive prediction among all the formulas (P > 0.05). The percentage of eyes with PE within ± 0.5 D was as follows: Barrett Universal II, 81.58%; Haigis, 78.95%; EVO, 76.32%; Olsen, 76.32%; Holladay I, 73.68%; SRK/T, 71.05%; Kane, 68.42%; and Hoffer Q, 65.79%.

CONCLUSION

The Barrett Universal II formula was more accurate than the other formulas for Chinese eyes with AL ≤ 22.5 mm.

Recommendation for Presbyopia-Correcting Intraocular Lenses: A Delphi Consensus Statement by the ESASO Study Group

PURPOSE

To establish consensus among experts in lens and refractive surgery to guide general ophthalmologists on issues related to presbyopia-correcting intraocular lenses (IOLs).

DESIGN

A modified Delphi method to reach a consensus among experts.

METHODS

A steering committee formulated 105 relevant items grouped into four sections (preoperative considerations, IOL selection, intraoperative considerations, and postoperative considerations). The consensus was defined as ≥ 70% of experts agreeing with the evaluation of a statement.

RESULTS

Ten experts participated and completed all rounds of questionnaires (100% response rate). Of 68 items considered in the preoperative considerations, consensus was achieved in 48 (70.6%). There was a lack of consensus over IOL selection, the experts only agreed on the importance of the patient's habits for the optical IOL design selection. Of the 14 considerations related to intraoperative issues, the experts reached a consensus on 10 (71.4%). The postoperative considerations section reached the highest consensus in 10 items of 13 (76.9%).

CONCLUSIONS

Key recommendations for a diffractive multifocal IOL were a potential postoperative visual acuity > 0.5, a keratometry between 40-45 diopters, a pupil >2.8 mm under photopic conditions and <6.0 mm under scotopic conditions, a root mean square of higher order corneal aberrations <0.5 µm for 6-mm pupil size, while monofocal or non-diffractive IOLs should be considered for patients with coexisting eye disorders. A lack of agreement was found in the issues related to the IOL selection.

Bioelectronic devices for light-based diagnostics and therapies

Light has broad applications in medicine as a tool for diagnosis and therapy. Recent advances in optical technology and bioelectronics have opened opportunities for wearable, ingestible, and implantable devices that use light to continuously monitor health and precisely treat diseases. In this review, we discuss recent progress in the development and application of light-based bioelectronic devices. We summarize the key features of the technologies underlying these devices, including light sources, light detectors, energy storage and harvesting, and wireless power and communications. We investigate the current state of bioelectronic devices for the continuous measurement of health and on-demand delivery of therapy. Finally, we highlight major challenges and opportunities associated with light-based bioelectronic devices and discuss their promise for enabling digital forms of health care.

The influence of corneal ablation patterns on prediction error after cataract surgery in post-myopic-LASIK eyes

Purpose

To evaluate the influence of corneal ablation patterns on the prediction error after cataract surgery in post-myopic-LASIK eyes.

Methods

Eighty-three post-myopic-LASIK eyes of 83 patients that underwent uneventful cataract surgery were retrospectively included. Predicted postoperative spherical equivalence (SE) was calculated for the implanted lens using the Haigis-L and Barrett True-K formula. Prediction error at one month postsurgery was calculated as actual SE minus predicted SE. For each eye, area and decentration of the ablation zone was measured using the tangential curvature map. The associations between prediction errors and corneal ablation patterns were investigated.

Results

The mean prediction error was − 0.83 ± 1.00 D with the Haigis-L formula and − 1.00 ± 0.99 D with the Barrett True-K formula. Prediction error was positively correlated with keratometry (K) value and negatively correlated with ablation zone area using either formula, and negatively correlated with decentration of the ablation zone using the Barrett True-K formula (all P < 0.05). In the K < 37.08 D group, prediction error was negatively correlated with decentration of the ablation zone with both formulas (all P < 0.05). Multivariate analysis showed that with the Haigis-L formula, prediction error was associated with axial length (AL), K value and decentration, and with the Barrett True-K formula, prediction error was associated with AL and decentration (all P < 0.05).

Conclusion

A flatter cornea, larger corneal ablation zone and greater decentration will lead to more myopic prediction error after cataract surgery in post-myopic-LASIK eyes.

Biometry and Intraocular Lens Power Calculation in Eyes with Prior Laser Vision Correction (LVC) - A Review

BACKGROUND

An intraocular lens (IOL) calculation in eyes that have undergone laser vision correction (LVC) poses a significant clinical issue in regards to both patient expectation and accuracy. This review aims to describe the pitfalls of IOL power calculation after LVC and give an overview of the current methods of IOL power calculation after LVC.

REVIEW

Problems after LVC derive from the measurement of anterior corneal radii, central corneal thickness, asphericity, and the predicted effective lens position. A central issue is that most conventional 3rd generation formulas estimate lens position amongst other parameters on keratometry, which is altered in post-LVC eyes.

CONCLUSION

An IOL power calculation results in eyes with prior LVC that are notably impaired in eyes without prior surgery. Effective corneal power including anterior corneal curvature, posterior corneal curvature, CCT (central corneal thickness), and asphericity is essential. Total keratometry in combination with the Barrett True-K, EVO (emmetropia verifiying optical formula), or Haigis formula is relatively uncomplicated and seems to provide good results, as does the Barrett True-K formula with anterior K values. The ASCRS ( American Society of Cataract and Refractive Surgery) calculator combines results of various formulae and averages results, which allows a direct comparison between the different methods. Tomography-based raytracing and the Kane and the Castrop formulae need to be evaluated by future studies.

Visual Outcomes of an Enhanced UV Protected Light Adjustable Lens Using a Novel Co-Managed, Open-Access Methodology

Purpose

To report on the safety and visual acuity (VA) outcomes using a co-managed, open-access methodology with a second-generation (ActivShield^TM) Light Adjustable Lens (LAL 2.0).

Patients and Methods

This retrospective observational case series of consecutive patients implanted with the LAL 2.0 choosing an emmetropic target in at least one eye were included in the study. All patients were co-managed with light treatments occurring at an open-access facility. Exclusion criteria included pathology of the macula and/or cornea with reduced best corrected visual acuity (BCVA). The primary outcome measures were uncorrected distance visual acuity (UDVA), spherical equivalent (SE), and residual cylinder for emmetropic goal eyes at the final 3- to 9-month postoperative visit.

Results

Thirty-three patients (62 eyes) were included in the study and implanted with the LAL 2.0. Thirty-three (53.2%) eyes had previous corneal refractive treatment(s) with 22 (66.7%) having no original historical refractive records available. Thirty-six (58.1%) total eyes and 20 (32.3%) postrefractive eyes had an emmetropic refractive target. Of all the emmetropic goal eyes, 35 (97.2%) saw 20/20 or better and 36 (100%) were within ±0.50 D SE of plano and had a mean cylinder of −0.15 ± 0.26 D. Of the postrefractive emmetropic goal eyes, 19 (95%) saw 20/20 or better, 20 (100%) were within ±0.50 D SE of plano and had a mean cylinder of −0.17 ± 0.28 D.

Conclusion

A co-managed, open-access methodology using the LAL 2.0 was safe and efficacious even in challenging postrefractive clinical scenarios.

Intraocular lens power calculation after radical keratotomy and photorefractive keratectomy: A case report

RATIONALE

To report a rare case of calculating the IOL power in a cataract patient who underwent both radial keratotomy (RK) and photorefractive keratectomy (PRK).

PATIENT CONCERNS

A 48-year-old woman underwent bilateral RK at age 22 and bilateral PRK at age 46. She developed bilateral corneal haze and corneal endothelial inflammation and received steroids therapy for long time after PRK. Then she was referred to our hospital due to decreased vision in the both eyes.

DIAGNOSES

The patient was diagnosed with binocular complicated cataract, corneal haze, high myopia and post corneal refractive surgery (RK and PRK).

INTERVENTIONS

The patient underwent bilateral phacoemulsification. The IOL power was calculated using SRK/T formula for RK and Haigis-L formula for PRK, respectively. We finally selected the Haigis-L formula and the intraocular lens (SN60WF) was implanted within the capsular bag.

OUTCOMES

After the surgery, both eyes showed myopia drift, and the right eye continuously fluctuated in refractive results. However, by nearly 1 year later, refractive results in both eyes had stabilized, and no other complications had occurred.

LESSONS

IOL power in patients who undergo both RK and PRK can be reliably calculated using the Shammas-PL, Average of multiple formulas, or Barret True-K No History formulas. Haigis-L formula is not suitable. Such patients require at least three months after surgery to attain refractive stability in both eyes.

Accuracy of Formulas for Intraocular Lens Power Calculation After Myopic Refractive Surgery

PURPOSE

To assess the accuracy of the following intraocular lens (IOL) power formulas: Barrett True-K No History (BTKNH), Emmetropia Verifying Optical 2.0 Post Myopic LASIK/PRK (EVO 2.0), Haigis-L, American Society of Cataract and Refractive Surgery (ASCRS) average, and Shammas, designed for patients who have undergone previous myopic refractive surgery, independent of preexisting clinical history and corneal tomographic measurements.

METHODS

Data from 302 eyes of 302 patients who previously underwent myopic refractive surgery and had cataract surgery done by a single surgeon with only one IOL type inserted were included. The predicted refraction was calculated for each of the formulas and compared with the actual refractive outcome to give the prediction error. Subgroup analysis based on the axial length and mean keratometry was performed.

RESULTS

On the basis of mean absolute prediction error (MAE), the formulas were ranked as follows: Haigis-L (0.61 diopters [D]), ASCRS average (0.63 D), BTKNH (0.67 D), EVO 2.0 (0.68 D), and Shammas (0.69 D). The Haigis-L had a statistically significant lower MAE compared with all formulas (P < .05) except the ASCRS average. Hyperopic mean prediction errors were seen in all formulas for axial lengths of greater than 30 mm or mean keratometry values of 35.00 diopters or less.

CONCLUSIONS

The Haigis-L and the ASCRS average formulas provided the most accurate results in the overall population evaluated in this study. Moreover, according to data observed, it is important to be careful handling very long eyes and very flat corneas because hyperopic refractions could be more common. [J Refract Surg. 2022;38(7):443-449.].

Toric intraocular lenses: Evidence‐based use

Uncorrected refractive astigmatism degrades visual acuity. Spherical intraocular lenses (IOLs) leave astigmatic errors resident in the cornea manifest in refractive astigmatism. Toric IOLs, correcting for this corneal astigmatism, contribute to spectacle‐free vision in the pseudophakic eye. This review provides information to assist surgeons in a rational choice of eyes suitable for toric IOL implantation, methods of IOL cylinder power calculation, surgical techniques for toric IOLs and management of complications. With appropriate application of this information, correction of visually detrimental astigmatism can be achieved routinely.

Efficacy of a Secondary Trifocal Sulcus IOL in Providing Near and Intermediate Vision in Patients with Prior Myopic Laser Vision Correction and Cataract Surgery

Purpose

To evaluate the visual function of patients with a history of prior laser vision correction and cataract surgery with implantation of a monofocal primary IOL after subsequent implantation of a secondary sulcus trifocal intraocular lens (IOL).

Setting

One clinical practice in Haugesund, Norway.

Design

Prospective, single arm, non-interventional unmasked study.

Methods

Eligible subjects who had previous laser vision correction and cataract surgery involving implantation of a monofocal IOL in the capsular bag of one or both eyes were subsequently implanted with a secondary IOL in the sulcus. Postoperative uncorrected and best distance-corrected visual acuities (VAs) were measured at distance (4 m), intermediate (60 cm), and near (40 cm), along with low contrast visual acuity and the monocular distance corrected defocus curve.

Results

Twenty-five eyes were evaluated from 7 to 24 months after trifocal implantation. The mean monocular uncorrected VAs were 0.06, 0.21 and 0.10 logMAR at distance, intermediate and near, respectively. Uncorrected near VA was 0.2 logMAR or better in 80% of eyes (20/25). VA of 0.2 logMAR or better at all test distances was achieved in 15/25 eyes (60%) in the uncorrected state and 17/25 eyes (68%) when corrected for distance vision. Binocular uncorrected distance visual acuity was 0.1 logMAR or better in all subjects while binocular uncorrected near visual acuity was 0.1 logMAR or better in all but one subject. The defocus curve showed a range of functional vision from distance to 30 cm. No adverse events were identified.

Conclusion

The trifocal sulcus IOL provided excellent distance and near vision and a good range of functional vision, similar to results obtained when a primary trifocal IOL is implanted. It is a viable option to provide better intermediate and near vision to patients with a prior history of refractive surgery and a monofocal IOL implanted.

Intraocular lens power calculations in eyes with previous corneal refractive surgery: Challenges, approaches, and outcomes

In eyes with previous corneal refractive surgery, difficulties in accurately determining corneal refractive power and in predicting the effective lens position create challenges in intraocular lens (IOL) power calculations. There are three categories of methods proposed based on the use of historical data acquired prior to the corneal refractive surgery. The American Society of Cataract and Refractive Surgery postrefractive IOL calculator incorporates many commonly used methods. Accuracy of refractive prediction errors within ± 0.5 D is achieved in 0% to 85% of eyes with previous myopic LASIK/photorefractive keratectomy (PRK), 38.1% to 71.9% of eyes with prior hyperopic LASIK/PRK, and 29% to 87.5% of eyes with previous radial keratotomy. IOLs with negative spherical aberration (SA) may reduce the positive corneal SA induced by myopic correction, and IOLs with zero SA best match corneal SA in eyes with prior hyperopic correction. Toric, extended-depth-of-focus, and multifocal IOLs may provide excellent outcomes in selected cases that meet certain corneal topographic criteria. Further advances are needed to improve the accuracy of IOL power calculation in eyes with previous corneal refractive surgery.