Intraocular lens power calculations in patients with extreme myopia

Refractive outcomes using Barrett formulas and patient characteristics of cataract surgery patients with and without prior LASIK/PRK

PURPOSE

The goal of this study is to describe characteristics of cataract surgery patients who previously underwent laser in situ keratomileusis/photorefractive keratectomy (LASIK/PRK) in comparison to non-LASIK/PRK cataract surgery patients including psychiatric comorbidities, as well as describe refractive prediction error after cataract surgery while accounting for axial length (AL) using the Barrett True-K and Barrett Universal II formulas.

METHODS

This was a retrospective study of patients from the University of Colorado Cataract Outcomes Registry. The primary outcomes were refraction prediction error (RPE), mean absolute RPE, and median absolute RPE. Outcomes were stratified by five axial length groups. Univariate and multivariate models for RPE were stratified by the AL group.

RESULTS

Two hundred eighty-one eyes with prior LASIK/PRK and 3101 eyes without are included in the study. Patients with prior LASIK/PRK were significantly younger: 67.0 vs 69.9 years, p < 0.0001. The LASIK/PRK group had significantly better mean pre-operative BCVA in comparison to the non-LASIK group, logMAR 0.204 vs logMAR 0.288, p = 0.003. The LASIK/PRK group had significantly lower rates of cardiovascular disease (18.5% vs 29.3%, p < 0.001), hypertension (49.1% vs 59.3%, p < 0.012), and type 2 diabetes (10.7% vs 26.0%, p < 0.001), and no significant difference in psychiatric disease. The absolute RPE was higher for the LASIK group for all ALs, but only significantly higher for eyes with AL less than 25 mm.

CONCLUSION

Patient eyes with prior LASIK/PRK surgery undergoing cataract surgery were significantly younger, had significantly less comorbidities, and a significantly better pre-operative BCVA. Using the Barrett formulas, absolute prediction error for eyes with longer ALs was not significantly worse for LASIK/PRK eyes than those without and the difference was smaller for eyes with longer AL.

Biometry challenges in the longest eyes we have encountered to date

Purpose

This report aims to present biometry challenges and solutions for a patient with the longest eyes we have encountered to date.

Observations

A 41-year-old woman with a history of Crouzon syndrome, extreme axial myopia, and posterior segment staphylomas was referred for cataract evaluation. Optical biometry was attempted using two partial coherence interferometry and optical low-coherence reflectometry devices that were available in 2011. Neither device could measure the axial length (AL) of either eye, unfortunately. We were able to measure them by A scan ultrasound, however, with results of 40.59 mm for the right eye and 38.29 mm for the left eye. Shortly thereafter, she underwent uncomplicated phacoemulsification with posterior chamber intraocular lens implantation under topical anesthesia. Twelve years later, she returned for repeat optical biometry with 3 newer generation devices, 2 of which utilized swept-source optical coherence tomography (SS-OCT). Only 1 SS-OCT device, the Argos biometer, was able to obtain AL measurements, and they were 40.54 mm and 40.84 mm for the right and left eyes, respectively.

Conclusions and importance

Biometry measurement using optical biometers on a patient with ALs greater than 40 mm was impossible in 2011 because of the relatively short gate for acceptable readings. Ultrasound biometry can also be challenging due to the presence of posterior staphylomas. However, a newer SS-OCT with a longer AL measurement capability enabled readings to be obtained more recently.

Improving the accuracy of the SRK/T formula in Chinese with implanting less than 10 D IOL calculated by the SRK/T formula: the SRK/T-Li formula

PURPOSE

To explore the accuracy of the improved SRK/T-Li formula in eyes following implantation of intraocular lens (IOL) of less than 10 D as calculated by using the SRK/T formula in Chinese.

METHODS

A total of 489 eyes from 489 patients with cataracts were included in this study. These patients were divided into a training set (271 patients) and a testing set (218 patients). The IOL power calculated by using SRK/T was less than 10 D. We evaluated the accuracy of the modified SRK/T-Li formula (P = PSRK/T × 0.8 + 2 (P = implanted IOL power; PSRK/T = IOL power calculated by SRK/T)). We evaluated the mean absolute error (MAE), percentage of prediction error (PE) within ± 0.25, ± 0.50, and ± 1.00 D, and the percentage of postoperative hyperopia.

RESULTS

The MAE values in order of lowest to highest were as follows: 0.412 D (SRK/T-Li), 0.414 D (Barrett Universal II, (BUII)), 0.814 D (SRK/T), and 1.039 D (Holladay 1). The percentage of PE within ± 0.25 D, ± 0.50 D, and ± 1.00 D was 38.99%, 69.27% and 92.66% (BUII), 40.83%, 69.27% and 94.04% (SRK/T-Li), 20.64%, 41.28% and 71.56% (SRK/T), and 7.34%, 16.51% and 53.21% (Holladay 1), respectively. SRK/T-Li had the smallest postoperative hyperopic shift.

CONCLUSIONS

For Chinese patients with an IOL power of less than 10 D as calculated by using the SRK/T, the SRK/T-Li has good accuracy and is the best choice to reduce postoperative hyperopic shift.

Network Meta-analysis of Intraocular Lens Power Calculation Formula Accuracy in 1016 Eyes With Long Axial Length

PURPOSE

To systematically review the literature and quantitatively synthesize the currently available evidence to compare the accuracy of different intraocular lens calculation formulas in eyes with long axial length (AL).

DESIGN

Network meta-analysis.

METHODS

PubMed, Embase, Web of Science, and the Cochrane Library were systematically searched for studies published between January 2000 and June 2022. Included were prospective or retrospective clinical studies reporting the following outcomes in cataract patients with long AL (ie, ≥26 mm): percentage of eyes with a prediction error (PE) within ±0.25, ±0.50, and ±1.00 diopters (D). Network meta-analysis was conducted using R software (version 4.2.1).

RESULTS

Ten prospective or retrospective clinical studies, including 1016 eyes and 11 calculation formulas, were identified. A traditional meta-analysis showed that for the percentage of eyes with PE within ±0.25 and ±0.50 D, the Olsen, Kane, and Emmetropia Verifying Optical (EVO) all had insignificantly higher percentages compared with others. Considering the percentage of eyes with PE within ±1.00 D, the original and modified Wang-Koch adjustment formulas for Holladay 1 (H1-WK and H1-MWK) and EVO formulas showed superiority, but the difference was insignificant. This network meta-analysis revealed that compared with the widely used Barrett Universal II (BUII) formula, the Olsen, Kane, and EVO formulas had higher percentages of eyes with PE within ±0.25, ±0.50, and ±1.00 D (all odds ratios >1 but P >.05). Based on the surface under the cumulative ranking area (SUCRA) values for the percentage of eyes with PE within ±0.25 D, the Olsen (96.4%), Kane (77.5%), and EVO (75.9%) formulas had the highest probability of being in the top 3 of the 11 formulas.

CONCLUSIONS

The Olsen, Kane, and EVO formulas may perform better than others in calculating IOL power in eyes with long AL. Nevertheless, there is still considerable uncertainty in this regard and the accuracy of these formulas in highly myopic eyes should be confirmed in studies based on large multicenter registries.

Refractive Predictability of a Swept Source Optical Coherence Tomography Biometer in Long and Short Eyes Implanted with Extended Depth of Focus Intraocular Lenses

Purpose

To determine the refractive predictability of Argos (Movu, a Santec company) measurements and the Barrett Universal II formula in long and short eyes implanted with an extended depth of focus (EDOF) intraocular lens (IOL).

Methods

This retrospective, non-interventional study included 86 eyes (55 long and 31 short) of 55 patients. Preoperative biometry was performed using the Argos. Preoperative IOL power formulas were the preprogrammed Barrett Universal II (BUII). Data were collected for refractive outcomes, postoperative prediction error (directional and absolute), and monocular corrected distance visual acuity (CDVA, Snellen).

Results

The mean absolute prediction error for BUII was 0.27 ± 0.26 D overall, 0.24 ± 0.20 D in long eyes, and 0.33 ± 0.33 D in short eyes. Overall, the percentage of eyes with ≤ 0.5 D prediction error was 84% for BUII. In long eyes, the percentage of eyes with ≤ 0.5 D prediction error was 90% for BUII. In short eyes, the percentage of eyes with ≤ 0.5 D prediction error was 74% for BUII. The percentage of eyes with ≤ 0.5 D of MRSE was 89% for long eyes and 94% for short eyes. Visual acuities were excellent in both long and short eyes, with > 90% of eyes 20/25 or better in each group.

Conclusion

The prediction error of Argos using BUII was low in long and short eyes at one month after EDOF IOL implantation.

Postoperative Outcome of Combined Phacovitrectomy in Eyes with Excessive Myopia (>-30 D)

Background

To report the outcomes of phacoemulsification combined with vitrectomy in eyes with extreme myopia (-30 diopters or more). Case Presentation. Three patients with cataract, vitreous opacities, and extreme myopia of more than -30 diopters underwent a combined surgical procedure of cataract extraction combined with vitrectomy. Postoperative refractive correction of the three cases ranged from -1.0 D to -2.5 D spherical equivalent. There was an obvious hyperopic shift of all cases. All patients noted a significant improvement in uncorrected and best-corrected visual acuity from 0.4 to 0.8 in case 1, from CF/70 cm to 1.0 in case 2, and from 0.12 to 0.5 in the right eye and 0.15 to 0.2 in the left eye in case 3. Vitreous floaters disappeared in all cases. No complications were noted during follow-up.

Conclusions

To the best of the authors' knowledge, these represent the first reported clinical cases of combined cataract extraction+vitrectomy surgery in eyes with extreme (>-30 D) myopia. Our results support the notion that phacoemulsification combined with vitrectomy may be a good therapeutic option for cataracts and vitreous floaters in cases with extreme myopia.

Binocular Visual Outcomes Comparison of Two Trifocal Intraocular Lenses in High-Myopic Cataract Patients: A 1-Year Multicenter Study

PURPOSE

To compare the postoperative visual outcomes and quality of vision obtained with 2 types of diffractive trifocal intraocular lenses (IOLs) in patients with highly myopic cataracts.

DESIGN

Prospective, multicenter, randomized controlled trial.

METHODS

Patients with high-myopic cataracts were randomized to binocular implantation of either the TFNT00 (n = 27) or the 839 MP (n = 28) trifocal IOLs at 3 surgery centers in China and were followed up for 1 year. Postoperative uncorrected distance, uncorrected intermediate, and uncorrected near visual acuity, and best-corrected distance visual acuity were measured. The defocus curve, high-order aberrations, modulation transfer function curve, Strehl ratio, and reading ability were compared between both groups. The functional vision and incidence of photic phenomena were surveyed using questionnaires.

RESULTS

Visual acuity at all ranges of vision was significantly improved in both groups. The TFNT00 group showed superior uncorrected intermediate visual acuity to that in the 839 MP group (P = .013). Reading ability at 40 and 60 cm was similar in both groups (P ≥ .05), whereas the preferred reading distances for near and intermediate were significantly different. The TFNT00 group had a significantly higher mean Visual Function Index 14 score, lower incidence of photic phenomena, and less posterior capsular opacity than the 839 MP group.

CONCLUSION

Bilateral implantation of both types of trifocal IOLs in patients with high-myopic cataracts provided good whole-course visual restoration, although recognition of fine Chinese characters remained impeded. As compared with 839 MP IOL, TFNT00 IOL resulted in greater patient satisfaction in intermediate activities, with a lower photic phenomena incidence.

Comparison of the prediction accuracy of 13 formulas in long eyes

PURPOSE

To investigate the accuracy of modern intraocular lens (IOL) power calculation formulas in eyes with axial length (AL) ≥ 26.00 mm.

METHODS

A total of 193 eyes with one type of lens were analysed. An IOL Master 700 (Carl Zeiss Meditec, Jena, Germany) was used for optical biometry. Thirteen formulas and their modifications were evaluated: Barrett Universal II, Haigis, Hoffer QST, Holladay 1 MWK, Holladay 1 NLR, Holladay 2 NLR, Kane, Naeser 2, SRK/T, SRK/T MWK, T2, VRF and VRF-G. The User Group for Laser Interference Biometry lens constants were used for IOL power calculation. The mean prediction error (PE) and its standard deviation (SD), the median absolute error (MedAE), the mean absolute error (MAE) and the percentage of eyes with PEs within ± 0.25 D, ± 0.50 D and <  ± 1.00 D were calculated.

RESULTS

The modern formulas (Barrett Universal II, Hoffer QST, Kane, Naeser 2 and VRF-G) produced the smallest MedAE among all methods (0.30 D, 0.30 D, 0.30 D, 0.29 D and 0.28 D, respectively). The percentage of eyes with a PE within ± 0.50 D ranged from 67.48% to 74.85% for SRK/T and Hoffer QST, Naeser 2 and VRF-G, respectively.

CONCLUSIONS

Dunn's post hoc test of the absolute errors revealed statistically significant differences (P < 0.05) between some of the newer formulas (Naeser 2 and VRF-G) and the remaining ones. From a clinical perspective the Hoffer QST, Naeser 2 and VRF-G formulas were more accurate predictors of postoperative refraction with the largest proportion of eyes within ± 0.50 D.

Comparison of intraocular lens power calculation formulas with and without total keratometry and ray tracing in patients with previous myopic SMILE

PURPOSE

To evaluate the prediction error (PE) variance and absolute median PE of different intraocular lens (IOL) calculation formulas including last-generation formulas such as Barrett True-K with K, Okulix and total keratometry (TK)-based calculations with Haigis, and Barrett True-K in a simulation model in post-small-incision lenticule extraction (SMILE) eyes.

SETTINGS

Department of Ophthalmology, University Hospital Marburg, Marburg, Germany.

DESIGN

Prospective study.

METHODS

Preoperative measurements included IOL power calculation before and after SMILE surgery. The target refraction was set to be the lowest myopic refractive error in pre-SMILE eyes. The IOL power targeting at the lowest myopic refractive error in pre-SMILE eyes was selected for the post-SMILE IOL calculation of the same eye. The difference between the predicted refraction of pre- and post-SMILE eyes with the same IOL power was defined as IOL difference. The refractive change induced by SMILE was defined as the difference between preoperative and postoperative manifest refraction.

RESULTS

98 eyes from 49 patients underwent bilateral myopic SMILE. The PE variance of Okulix was not significantly different compared with Barrett True-K with TK ( P = .471). The SDs of the mean PEs were ±0.413 D (Haigis-TK), ±0.453 D (Okulix), ±0.471 D (Barrett True-K with TK), ±0.556 D (Haigis-L), and ±0.576 D (Barrett True-K with K). The mean absolute PE was 0.340 D, 0.353 D, 0.404 D, 0.511 D, and 0.715 D for Haigis-TK, Okulix, Barrett True-K with TK, Barrett True-K with K, and Haigis-L, respectively. The highest percentage of eyes within ±0.50 D was achieved by Okulix, followed by Haigis-TK, Barrett True-K with TK, Barrett True-K with K, and Haigis-L.

CONCLUSIONS

Results suggest that Haigis in combination with TK, Okulix, and Barrett True-K with and without TK offer good options for accurate IOL power calculation after SMILE. Haigis-L showed a tendency for myopic shift in eyes after previous SMILE.

Changes in axial length after vitrectomy for rhegmatogenous retinal detachment combined with choroidal detachment

AIM

To report the postoperative axial length (AL) changes in rhegmatogenous retinal detachment combined with choroidal detachment (RRD-CD) patients.

METHODS

The medical records of 97 consecutive patients from January 2015 to December 2018 were reviewed. Patients included were divided into RRD-CD and RRD only groups. All patients had received AL measurements before pars plana vitrectomy (PPV) and before silicone oil removal (SOR). The changes in AL of the two groups were compared. In addition, the potential factors related to AL changes were analyzed.

RESULTS

AL elongation after PPV was 1.01 mm [interquartile range (IQR): 0.37, 1.79; P=0.02] in the RRD-CD group, which was greater than in RRD only group (0.15 mm, IQR: 0.04, 0.41; P<0.001). AL increased 0.06 mm per 1 mm Hg intraocular pressure changes in the RRD-CD group (R ²=0.11, P=0.03). RRD-CD patient was 11.42 times (3.54-46.80) more likely to experience post-PPV AL elongation of more than 1 mm [P<0.001, Akaike information criterion (AIC)=92.33, area under the curve (AUC)=0.839].

CONCLUSION

RRD-CD patients are very likely to have a postoperative elongation of AL. The primary intraoclular lens implantation using presurgery AL data may cause a significant refractive error in RRD-CD patients who underwent PPV.

Assessing Accuracy of Okulix Ray-Tracing Software in Calculating Intraocular Lens Power in the Long Cataractous Eyes

Purpose

To investigate the accuracy of Okulix ray-tracing software in calculating intraocular lens (IOL) power in the long cataractous eyes and comparing the results with those obtained from Kane, Holladay 1 with optimized constant, SRK/T with optimized constant, Haigis with optimized constant, and Barret Universal 2 formulas.

Methods

The present study evaluates the refractive results of cataract surgery in 85 eyes with axial length > 25 mm and no history of ocular surgery and corneal pathology. IOL power calculation was performed using the Okulix software. The performances of Okulix software in comparison with the five other formulas were evaluated by predicted error, mean absolute error, and mean numerical error 6 months after surgery.

Results

The mean calculated IOL power by the Okulix software was +13.48 ± 4.19 diopter (D). The mean of the 6-month postoperative sphere and spherical equivalent were +0.18 ± 0.63 and -0.34 ± 0.78 D, respectively. Also, the 6-month spherical equivalent in 56.6% and 80% of eyes were within ±0.05 and ±1.00 D, respectively. The predicted error (P < 0.001) and the mean numerical error (P < 0.001) were different between the six studied methods; however, we were not able to find any significant differences in the mean absolute error among six studied methods (P: 0.211).

Conclusion

The present study showed acceptable performance of the Okulix software in IOL power calculation in long eyes in comparison with the other five methods based on the postoperative refractive error, calculated mean absolute error, and mean numerical error.

Longitudinal changes in axial length in high myopia: a 4-year prospective study

AIM

To determine the longitudinal changes in the axial length (AL) in patients with high myopia without any other ophthalmic disease METHODS: Participants were divided into two groups: a high myopia group (60 eyes) without myopic degeneration, such as chorioretinal atrophy or posterior staphyloma, and a control group (60 eyes). Both groups were further divided into subgroups according to the AL: subgroup 1 (≥27.5 mm), subgroup 2 (26.0-27.5 mm), subgroup 3 (24.5-26.0 mm) and subgroup 4 (<24.5 mm). The ALs were measured five times at 1-year interval using an IOL master, and the AL was fitted with linear mixed models.

RESULTS

In the high myopia group, the AL showed a relatively constant increase at each visit, and they were significantly different with previous measurements at most visits, whereas the control group showed no significant change of AL. Subgroups 1,2 and 3 showed significant changes in AL over time (0.064, 0.032 and 0.012 mm/y, respectively). In univariate analyses, age, best-corrected visual acuity, baseline AL and anterior chamber depth were significantly correlated with changes in the AL in the high myopia group. In multivariate analysis, only baseline AL remained significant (p<0.001).

CONCLUSIONS

Myopic eyes, including moderately myopic eyes, showed a consistent increase in AL over 4 years, and eyes with a longer baseline AL showed a greater increase in AL than eyes with a shorter AL.

Ocular biometry and refractive outcomes using two swept-source optical coherence tomography-based biometers with segmental or equivalent refractive indices

This study compared the axial length (AL), central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT), mean anterior corneal radius of curvature (Rm), and postoperative refractive outcomes obtained from two different swept-source optical coherence biometers, the ARGOS (Movu, Nagoya, Japan), which uses the segmental refractive index for each segment, and the IOLMaster 700 (Carl Zeiss Meditec, Jena, Germany), which uses an equivalent refractive index for the entire eye. One hundred and six eyes of 106 patients with cataracts were included. The refractive outcomes using the Barrett Universal II, Haigis, Hoffer Q, and SRK/T formulas were evaluated. The mean AL, CCT, ACD, and Rm differed significantly (P < 0.001) with the IOLMaster 700 (25.22 mm, 559 µm, 3.23 mm, and 7.69 mm) compared with the ARGOS (25.14 mm, 533 µm, 3.33 mm, and 7.66 mm). The mean LTs did not differ significantly. The percentages of eyes within ±0.50 and ±1.00 diopter of the predicted refraction did not differ significantly (P > 0.05). The accuracy of the intraocular lens power calculations was clinically acceptable with both biometers, although the ocular biometry using these two biometers exhibited certain differences.

Intraocular lens power calculation in eyes with extreme myopia: Comparison of Barrett Universal II, Haigis, and Olsen formulas

PURPOSE

To compare the accuracy of the Barrett Universal II, Haigis, and Olsen formulas in calculating intraocular lens (IOL) power in eyes with extreme myopia.

SETTING

Eye and Ear, Nose, and Throat Hospital, Fudan University, Shanghai, China.

DESIGN

Prospective case series.

METHODS

Eyes were divided into 3 axial length (AL) groups as follows: 26.0 to 28.0 mm (control), 28.0 to 30.0 mm (extreme myopia 1), and 30.0 mm or more (extreme myopia 2). The mean error (ME) 1 month postoperatively was adjusted to zero by optimizing the lens factor; then, the median absolute errors (MedAEs) were compared between formulas. Factors associated with postoperative refractive errors were analyzed.

RESULTS

After optimization, the MEs of the Barrett Universal II, Haigis, and Olsen formulas were 0.04 diopter (D) ± 0.48 (SD), 0.04 ± 0.66 D, and 0.04 ± 0.52 D, respectively, and the MedAEs were 0.37 D, 0.46 D, and 0.39 D, respectively (P = .044; Haigis versus Barrett: P = .038). In the extreme myopia 1 group, all 3 formulas produced small MedAEs (P = .662). In the extreme myopia 2 group, the Haigis formula produced a significantly greater MedAE than the Barrett Universal II formula (P = .007; Haigis versus Olsen: P = .055). The accuracy of the Haigis formula in myopic eyes was affected by the AL and keratometry value, whereas the accuracy of the Barrett Universal II and Olsen formulas was affected by the AL only.

CONCLUSIONS

In eyes with an AL of 28.0 to 30.0 mm, all 3 formulas were accurate. In eyes with AL of 30.0 mm or more, the Barrett Universal II formula was better than the Haigis formula, possibly because there were fewer influencing factors.

Comparison of axial length, anterior chamber depth and intraocular lens power between IOLMaster and ultrasound in normal, long and short eyes

PURPOSE

To compare the axial length (AL), anterior chamber depth (ACD) and intraocular lens power (IOLP) of IOLMaster and Ultrasound in normal, long and short eyes.

METHODS

Seventy-four normal eyes (≥ 22 mm and ≤ 25 mm), 74 long eyes (> 25 mm) and 78 short eyes (< 22 mm) underwent AL and ACD measurements with both devices in the order of IOLMaster followed by Ultrasound. The IOLP were calculated using a free online LADAS IOL formula calculator.

RESULTS

The difference in AL and IOLP between IOLMaster and Ultrasound was statistically significant when all three groups were combined. The difference in ACD between IOLMaster and Ultrasound was statistically significant in the normal group (P<0.001) and short eye group (P<0.001) but not the long eye group (P = 0.465). For the IOLP difference between IOLMaster and Ultrasound in the normal group, the percentage of IOLP differences <|0.5|D, ≥|0.5|D<|0.75|D, ≥|0.75|D<|1.0|D, and ≥|1.0|D were 90.5%, 8.1%, 1.4% and 0%, respectively. For the long eye group, they were 90.5%, 5.4%, 4.1% and 0%, respectively. For the short eye group, they were 61.5%, 23.1%, 10.3%, and 5.1%, respectively.

CONCLUSIONS

IOLMaster and Ultrasound have statistically significant differences in AL measurements and IOLP (using LADAS formula) for normal, long eye and short eye. The two instruments agree regarding ACD measurements for the long eye group, but differ for the normal and short eye groups. Moreover, the high percentage of IOLP differences greater than |0.5|D in the short eye group is noteworthy.

Optical Biometry Derived Axial Length Measurements Following Intravitreal Anti-Vascular Endothelial Growth Factor Treatment for Macular Edema

PURPOSE

To evaluate axial length (AL) alterations in patients with macular disease over the course of intravitreal anti-vascular endothelial growth factor (anti-VEGF) treatment.

METHODS

In this prospective, comparative study, 33 patients with macular edema underwent unilaterally intravitreal anti-VEGF therapy and were followed for two months; the contralateral eyes were considered as controls. Central retinal thickness (CRT) was measured with spectral-domain optical coherence tomography and AL with an IOL-Master optical biometer.

RESULTS

CRT of the treated eyes decreased by 35.33 ± 65.59 μm (range, -222.00-67 μm), while AL increased by 0.008 ± 0.062 mm (range, -0.11-0.18 mm). CRT of the control group decreased by 9.82 ± 65.40 μm (range, -203-182 μm), and AL increased by 0.011 ± 0.129 mm (range, -0.20-0.67 mm). No significant correlation was detected between CRT and AL parameters (rhos=0.026, P=0.882).

CONCLUSIONS

Anti-VEGF administration has no significant impact on optical biometry-derived AL measurements.

Performance of the SRK/T formula using A-Scan ultrasound biometry after phacoemulsification in eyes with short and long axial lengths

BACKGROUND

The SRK/T formula is one of the third generation IOL calculation formulas. The purpose of this study was to evaluate the performance of the SRK/T formula in predicting a target refraction ±1.0D in short and long eyes using ultrasound biometry after phacoemulsification.

METHODS

The present study was a retrospective analysis, which included 38 eyes with an AL < 22.0 mm (short AL), and 62 eyes ≥24.6 mm (long AL) that underwent uncomplicated phacoemulsification. Preoperative AL was measured by ultrasound biometry and SRK/T formula was used for IOL calculation. Three different IOLs were implanted in the capsular bag. The prediction error was defined as the difference between the achieved postoperative refraction, and attempted predicted target refraction. Statistical analysis was performed with SPSS V21.

RESULTS

In short ALs, the mean age was 65.13 ± 9.49 year, the mean AL was 21.55 ± 0.45 mm, the mean K1 and K2 were 45.76 ± 1.77D and 46.09 ± 1.61D, the mean IOL power was 23.96 ± 1.92D, the mean attempted (predicted) value was 0.07 ± 0.26D, the mean achieved value was 0.07 ± 0.63 D, the mean PE was 0.01 ± 0.60D, and the MAE was 0.51 ± 0.31D. A significant positive relationship with AL and K1, K2, IOL power and a strong negative relationship with PE and achieved postoperative was found. In long ALs, the mean age was 64.05 ± 7.31 year, the mean AL was 25.77 ± 1.64 mm, the mean K1 and K2 were 42.20 ± 1.57D and 42.17 ± 1.68D, the mean IOL power was 15.79 ± 5.17D, the mean attempted value was -0.434 ± 0.315D, the mean achieved value was -0.42 ± 0.96D, the mean PE was -0.004 ± 0.93D, the MAE was 0.68 ± 0.62D. A significant positive relationship with AL and K1, K2 and a significant positive relationship with PE and achieved value, otherwise a negative relationship with AL and IOL power was found. There was a little tendency towards hyperopic for short ALs and myopic for long ALs. The majority of eyes (94.74 %) for short ALs and (70.97 %) for long ALs were within ±1 D of the predicted refractive error. No significant relationship with PE and IOL types, AL, K1, K2, IOL power, and attempted value, besides with MAE and AL, K1, K2, age, attempted, achieved value were found in both groups.

CONCLUSION

The SRK/T formula performs well and shows good predictability in eyes with short and long axial lengths.

Cataract surgery in the setting of severe pathologic myopia with high axial length: use of pars plana lensectomy and vitrectomy

Cataract surgery in patients with pathologic myopia and high axial length can be challenging for a variety of reasons, including imprecise intraocular lens calculations in eyes with posterior staphylomas and intraoperative complications such as suprachoroidal hemorrhage, posterior capsular rupture, and retinal tears. Although most surgeons recommend standard phacoemulsification and preservation of the posterior capsule in these cases, an alternative approach presented in this series entails the removal of the lens through the pars plana and removal of formed vitreous during the concurrent procedure.

Distribution of axial length, anterior chamber depth, and corneal curvature in an aged population in South China

Background

Ocular biometry is important for preoperative assessment in cataract and anterior segment surgery. The purpose of this study was to investigate normative ocular biometric parameters and their associations in an older Chinese population.

Methods

This was a cross-sectional observational study. From 2013 to 2014, we recruited inhabitants aged 50 years or older in Guangzhou, China. Among 1,117 participants in the study, data from 1,015 phakic right eyes were used for analyses. Ocular parameters including axial length (AL), anterior chamber depth (ACD), and corneal curvature (K) were measured using an IOL Master.

Results

The mean AL, ACD, and K were 23.48 mm [95 % confidence interval (CI), 23.40–23.55], 3.03 mm (CI, 3.01–3.05), and 44.20 mm (CI, 44.11–44.29), respectively. A mean reduction in ACD with age was observed (P = 0.002) in male subjects but not in female subjects (P = 0.558). Male subjects had significantly longer ALs (23.68 mm versus 23.23 mm, P < 0.001), deeper ACDs (3.13 mm versus 2.95 mm, P < 0.001), and flatter Ks (43.85D versus 44.50 D, P < 0.001) than female subjects. Eyes with axial elongation had a flatter cornea (r = −0.437, P < 0.001) and a deeper anterior chamber (r = 0.652, p < 0.001). The ACD was correlated with K (r = −0.266, P < 0.001).

Conclusions

These data provide normative values for AL, ACD, and K using the IOL Master for a population in South China. The AL in this Chinese cohort was greater than that observed in the Singaporean Chinese but smaller than that observed in Malaysia and for Caucasians. The Chinese have a shallower ACD than some other racial groups. Age and sex were the most consistent predictors of ocular biometry in the older population from South China.

Accuracy of Intraocular Lens Power Formulas Involving 148 Eyes with Long Axial Lengths: A Retrospective Chart-Review Study

Purpose. This study aims to compare the accuracy of intraocular lens power calculation formulas in eyes with long axial lengths from Chinese patients subjected to cataract surgery. Methods. A total of 148 eyes with an axial length of >26 mm from 148 patients who underwent phacoemulsification with intraocular lens implantation were included. The Haigis, Hoffer Q, Holladay 1, and SRK/T formulas were used to calculate the refractive power of the intraocular lenses and the postoperative estimated power. Results. Overall, the Haigis formula achieved the lowest level of median absolute error 1.025 D (P < 0.01 for Haigis versus each of the other formulas), followed by SRK/T formula (1.040 D). All formulas were least accurate when eyes were with axial length of >33 mm, and median absolute errors were significantly higher for those eyes than eyes with axial length = 26.01-30.00 mm. Absolute error was correlated with axial length for the SRK/T (r = 0.212, P = 0.010) and Hoffer Q (r = 0.223, P = 0.007) formulas. For axial lengths > 33 mm, eyes exhibited a postoperative hyperopic refractive error. Conclusions. The Haigis and SRK/T formulas may be more suitable for calculating intraocular lens power for eyes with axial lengths ranging from 26 to 33 mm. And for axial length over 33 mm, the Haigis formula could be more accurate.

Refractive errors in high myopic eyes after phacovitrectomy for macular hole

AIM

To examine the refractive prediction error in high myopic eyes after phacovitrectomy.

METHODS

This retrospective comparative case series included 91 eyes (18 high myopic eyes and 73 non-high myopic eyes) of 91 patients who underwent successful phacovitrectomy (phacoemulsification, intraocular lens implantation, and pars plana vitrectomy). The high myopic eyes were defined as the eye with more than 26.0 mm of axial length. The postoperative prediction error of mean error and mean absolute error were evaluated at 4mo postoperatively. Axial length and keratometry measurement were performed preoperatively and 4mo postoperatively using the IOL Master.

RESULTS

The refractive outcome after phacovitrectomy showed significantly greater myopic shift in the high myopic eyes [-1.08±0.87 diopters (D)] than that in the non-high myopic eyes (-0.43±0.63 D, P=0.004). Axial length and keratometric value in the high myopic eyes were significantly increased (P=0.043, 0.037 respectively), whereas those in the non-high myopic group were not significantly increased (P=0.135, 0.347 respectively). The change of the axial length in the myopic eye (0.46±0.28 mm) was greater than that in the non-high myopic eye (0.11 ± 0.34 mm; P<0.001).

CONCLUSION

High myopic eyes showed more myopic shift than non-high myopic eyes after phacovitrectomy. The cause of myopic shift in high myopic eyes seems to be attributed to actual elongation of the axial length in high myopia.

Comparison of two multifocal intraocular lens designs that differ only in near add

PURPOSE

To evaluate monocular functional outcomes after the implantation of the AcrySof ReSTOR SN6AD2 intraocular lens (IOL) (+2.5 diopters [D] near add) (Alcon Laboratories, Inc., Fort Worth, TX) and the AcrySof ReSTOR SN6AD1 IOL (+3.0 D near add) (Alcon Laboratories, Inc.).

METHODS

This prospective, comparative, nonrandomized single-blind observational study comprised 62 eyes of 62 patients that underwent phacoemulsification and implantation of a multifocal IOL: SN6AD2 (31 eyes) (+2.5 group) and SN6AD1 (31 eyes) (+3.0 group). Twelve months after surgery, monocular near (30 and 40 cm), intermediate (50, 60, and 70 cm), and distance (4 m) visual acuity were evaluated with the internal root mean square and modulation transfer function. Both parameters were evaluated at the 4- and 6-mm pupil sizes.

RESULTS

No statistical differences at 4 m were found between the groups. The +2.5 group obtained better performances at all intermediate distances (50 cm, 0.23 ± 0.14 vs 0.32 ± 0.13; 60 and 70 cm, 0.21 ± 0.10 vs 0.41 ± 0.14 and 0.24 ± 0.10 vs 0.53 ± 0.17, respectively), whereas the near visual acuity was better for the +3.0 group (30 and 40 cm, 0.36 ± 0.18 vs 0.14 ± 0.09 and 0.36 ± 0.19 vs 0.17 ± 0.07, respectively). The root mean square was lower for the +2.5 group compared to the +3.0 group, whereas the modulation transfer function showed overlapping results between the two models.

CONCLUSIONS

Both IOL models showed good results in distance vision; the +2.5 D IOL seemed to provide better intermediate vision than the +3.0 D IOL. For near vision, the +3.0 D model performed better than the +2.5 D model.

[Uncorrected visual function after cataract surgery]

PURPOSE

To study the relationship between refraction after cataract surgery and the use of spectacles in patients older than 65 years.

METHODS

Retrospective case control study. The study included 40 retired subjects older than 65 years-old who fulfilled our inclusion criteria. Clinical ophthalmic and optical information was collected, and patients were requested to complete a validated questionnaire of visual function (VF14) and a test of independence of spectacles. The difference between VF14 test results with and without glasses (difVF14) was calculated.

RESULTS

The study included 16 men and 24 women, with a mean age of 74 years. There was a significant correlation between difVF14 and postoperative refraction, with lower difVF14 values associated with postsurgical refraction in the range -0.50 to -1.00 D (OD 0.479 [95% CI; 0.286-0.804]). The questionnaire of independency of lenses did not show significant correlation with postoperative refraction.

CONCLUSIONS

Patients with postsurgical refraction between -0.50 and -1.00 diopters displayed better visual function without glasses than those with refraction out of that range. Neutral distant refraction and positive lenses for near vision might not be the ideal solution for every patient. Postsurgical refraction should be individualized for each patient according to their personal preferences, in order to achieve the best visual function and the best vision-related quality of life.

A study to evaluate whether CTR increases refractive unpredictability between predicted and actual IOL position

BACKGROUND

The surgical management of cataract associated with extensive zonular loss presents a challenge for ophthalmic surgeon. Capsular Tension Ring (CTR) is commonly being used to stabilize the capsular bag in patients with zonular dialysis. CTR helps to avoid capsular collapse and vitreous presentation in AC during surgery and maintains the capsular bag, allowing the circular contour of the capsular bag, allowing intra ocular lens to be easily placed in the bag. The aim of the study was to know if there is any shift of IOL following use of CTR ring.

METHOD

We did a Ultrabiomicroscopy (UBM) examination to find out shift in PCIOL in cases in which CTR ring and compared it with cases without CTR ring.

RESULT

It was found out through UBM in this study that there is actually a posterior shift of PCIOL after use of CTR ring leading to hypermetropic correction needed after surgery.

CONCLUSION

It is suggested that posterior shift of IOL following use of CTR should be kept in mind and the IOL implanted should be of + 1.0 to 2.0 D more than that calculated preoperatively.

Lenstar versus ultrasound for ocular biometry in a pediatric population

PURPOSE

To compare the central corneal thickness (CCT), axial length (AL), anterior chamber depth (ACD), and lens thickness (LT) measured with Lenstar with those obtained with ultrasound pachymetry and A-scan contact ultrasound (ASU) in children.

METHODS

ODs of 565 school children were included. All measurements were obtained 30 min after instilling 1% tropicamide. For each instrument, three consecutive measurements per each child were performed. Initially, examiner 1 performed measurements with Lenstar to obtain CCT, AL, ACD, and LT. Later, examiner 2 performed measurements with corneal pachymetry to obtain CCT. Finally, ASU was used by examiner 2 to obtain AL, ACD, and LT. Four parameters obtained with Lenstar were compared with those obtained with pachymetry and ASU using Pearson correlation coefficients (r) and Bland-Altman analyses.

RESULT

Lenstar measurements were obtained in 557 of 565 subjects(mean age; 10.48 ± 2.11 years, mean spherical equivalent of the ODs; +0.47 ± 1.18 diopters) whereas ASU and pachymetry could be performed in 530 of 565. Four hundred seventy-nine subjects were statistically assessed after 41 subjects were extracted as outliers from 530 subjects in whom all instruments could be performed. Mean difference between pachymetry and Lenstar was 13.20 ± 13.13 μm [95% confidence interval (CI): 12.01 to 14.37]. Mean difference between ASU and Lenstar was -0.72 ± 0.35 mm (95% CI: -0.75 to -0.69) for AL, -0.27 ± 0.32 mm (95% CI: -0.30 to -0.24) for ACD, and 0.24 ± 0.28 mm (95% CI: 0.22 to 0.27) for LT. R values were 0.912 (p < 0.001), 0.904 (p < 0.001), 0.487 (p < 0.001), 0.369 (p < 0.001) for CCT, AL, ACD, and LT respectively.

CONCLUSIONS

AL and ACD were found to be greater with Lenstar, whereas CCT and LT measures were smaller. It is concluded that there was agreement between instruments for CCT and ACD, because the small differences between measures were clinically insignificant. AL and LT values cannot be used interchangeably. If these differences are considered, Lenstar can replace ASU and pachymetry for the majority of children.

Accuracy of intraocular lens power calculation using partial coherence interferometry in patients with high myopia

PURPOSE

Ultrasound-A-scan-biometry intraocular lens power calculation for cataract surgery sometimes shows lack of accuracy in patients with high myopia. The purpose of this retrospective study was to assess the accuracy of lens power calculation with optical biometry using the Zeiss IOLMaster across a large range of myopia levels.

METHODS

We included 37 consecutive, myopic eyes with an axial length >26.5mm (31 patients, 62±13years old, average preoperative refraction of -14.46±6.61D, range -3.5 to -32.0D which underwent phacoemulsification and implantation of an intraocular lens following biometry using the IOLMaster. For lens power calculation, the Haigis formula was used in all cases. For comparison, refraction was back-calculated using the SRK/T and Holladay I formulae.

RESULTS

  The preoperative mean axial length was 29.37±2.44 mm with a range of 26.50-35.52mm. Thirty eyes (81.1%) showed a postoperative spherical equivalent which differed 1.00D or less from the predicted value, in 20 cases (54.1%) the postoperative refractive error was within±0.50D. The mean absolute error (MAE) was 0.70±0.59D (Holladay I, 0.85±0.68; SRK/T, 1.01±0.61D).

CONCLUSIONS

  Optical biometry for intraocular lens power calculation seems to deliver reliable results for cataract surgery in patients with high myopia, although our data describe an increasing lack of accuracy beyond an axial length of 30mm. The Haigis formula provided the best predictability of postoperative refractive outcome for myopic eyes in general.

[Refractive predictability and stability of three-piece versus single-piece intraocular lenses in patients with high axial myopia]

BACKGROUND

Based on previous data on single-piece and three-piece intraocular lenses (IOLs) there is no evidence for significant differences in decentration, tilt and refractive shift. The purpose of the current study was to compare single-piece and three-piece IOLs in patients with high axial myopia.

MATERIAL AND METHODS

A total of 68 eyes of 50 patients with high axial myopia (axis length ≥ 28.00 mm) with and without cataract who underwent complication-free phacoemulsification and IOL implantation were retrospectively examined. To compare single-piece and three-piece IOLs, the patients were retrospectively grouped depending on IOL type: group 1 acrylic single-piece IOL (n = 37; ACR6D SE, Corneal, France) and group 2 acrylic three-piece IOL with fixed haptic frame (n = 31; AF-1 UY, Hoya, Japan). Patient files were analyzed regarding best spectacle-corrected visual acuity (BSCVA), refractive predictability and stability.

RESULTS

In this study the mean BSCVA was determined as 0.22 ± 0.12 logMAR and 0.13 ± 0.11 logMAR 6 months postoperatively for the ACR6D SE group and the AF-1 UV group, respectively (p = 0.09). Refractive predictability was less accurate in the ACR6D SE (+ 1.75 ± 2.2 dpt) compared to the AF-1 UV (- 0.37 ± 1.1) treated eyes (p = 0.001). Refractive stability, defined as the difference in diopters between the first week and the sixth month after surgery, resulted in  + 0.40 ± 1.7 dpt and -0.16 ± 1.2 dpt for the ACR6D SE and the AF-1 UV, respectively (p = 0.022).

CONCLUSIONS

The three-piece AF-1 UV showed satisfactory refractive predictability and stability in patients with high axial myopia. The ACR6D SE has a high refractive unpredictability and should not be used in eyes with high axial myopia.

Accuracy of intraocular lens power calculation in high myopia

Purpose

To study the accuracy of different recent intraocular lens (IOL) calculation formulas in predicting a target postoperative refraction ± 1.0D (Diopters) in patients with long eyes (axial length ≥ 26.0 mm) undergoing phacoemulsification.

Materials and Methods

This study comprised 127 eyes of 87 patients who presented with cataract and axial eye length ≥ 26 mm. Before phacoemulsification and IOL implantation; axial length measurement using immersion ultrasound A-scan technique, and autokeratometry with or without computerized corneal topography for K readings were done. The IOL power was calculated using four formulas, namely the SRK-T, Hoffer-Q, Holladay-2, and Haigis formulas. Four months after surgery, refraction was done. Differences between actual postoperative refraction and assumed target refraction using the different formulas were analyzed. P < 0.05 was considered statistically significant.

Results

In all 127 eyes, the mean axial length was 31.71 mm (range, 26.06–37.11 mm) and the mean K was 44.68 D (range, 40.05–55.14D). The mean preoperative spherical equivalent (SE) was −17.52D (range, −12.25 to −30.50D). After surgery, the mean spherical equivalent was −0.8 ± 0.83D (range, +1.25 to −3.75D). The mean postoperative refractive SE when implanting a plus power IOLs was −0.3 ± 0.51D (P < 0.001) while the mean postoperative refractive SE when implanting a minus power IOLs was +1.21 ± 0.11D denoting a highly significant tendency toward hyperopia (P < 0.001). Concerning the minus power group, most postoperative refractive error was within +1.0 to +2.0D in the actual implanted IOL and in all other formula calculated IOL power. However, Haigis formula showed the least deviation while SRK-T and other formulas showed a greater tendency toward hyperopia.

Conclusions

In eyes with high axial myopia, the performance of SRK-T, Hoffer-Q, Holladay-2 and Haigis formulas are comparable in low plus-powered IOL implantation. Haigis formula is the best formula when minus power IOL is implanted.

Combined correction of axial hyperopia and astigmatism using the light adjustable intraocular lens

PURPOSE

To determine whether residual spherical and cylindrical errors could be corrected postoperatively using spatially profiled UV light irradiation in patients with axial hyperopia undergoing cataract surgery and implantation of a light adjustable, silicone intraocular lens (LAL).

DESIGN

We conducted a prospective, nonrandomized clinical trial. The LALs were implanted in eyes with axial lengths <22.20 mm and were treated with a spatial intensity profile delivered by a digital light delivery device to induce a targeted spherical and cylindrical refractive change postoperatively. Once the desired correction was achieved, the LAL was treated again to lock-in the lens power.

PARTICIPANTS

We studied 15 eyes of 15 patients with axial hyperopia.

METHODS

The manifest refraction, uncorrected visual acuity (UCVA), and best spectacle-corrected visual acuity (BCVA) were determined with follow-up time of 12 months to determine the achieved refractive corrections and their stability.

MAIN OUTCOME MEASURES

We measured UCVA, BCVA, achieved versus targeted refractive outcome, and refractive stability with a follow-up time of 12 months.

RESULTS

Of 15 eyes, 14 (93%) achieved ± 0.5 diopters (D), and 10 (67%) were within ± 0.25 D of the targeted refractive adjustment up to 12 months postoperative follow-up. Only 1 treated eye showed a change of 0.38 D in manifest spherical equivalent refraction, the remaining 14 eyes showed <0.25 D change between 1 month post lock-in, and at the 3-, 6-, and 12-month postoperative visits.

CONCLUSIONS

The light-adjustable lens is a promising technology with the potential to reduce the rate of postoperative refractive surprises up to 2 D of spherical and cylindrical errors after cataract surgery. Postoperative refractive errors were successfully corrected with precision and significant improvement in UCVA and without compromising BCVA using the light-adjustable intraocular lens technology. The data demonstrate the stability of the achieved refractive change after the adjustment and lock-in procedures.

Intra-ocular lens power calculation in patients with high axial myopia before cataract surgery

PURPOSE

To evaluate the accuracy of different formulas used for IOL power calculation in patients with high axial myopia undergoing cataract surgery.

METHODS

A prospective clinical study was carried out on 53 eyes of 51 patients with an axial length from 25.5 to 31.4 mm including 21 males (41.2%) and 30 females (58.8%). Calculation of the IOL power to be implanted was done by three available IOL power formulas; Haigis formula, SRK/T formula, and Holladay I formula. The mean error (ME) was calculated from the difference between the formula predicted refractive error and the actual post operative refractive error.

RESULTS

There was no statistically significant difference between the mean error of the three formulas used in the overall performance or in the axial length subcategories. SRK/T formula caused the smallest mean error, (+0.17 D). Haigis formula showed a higher ME (+0.21 D) and Holladay formula caused a myopic postoperative refractive error (-0.20 D).

CONCLUSION

The calculation of IOL power in patients with high axial myopia using the third or the fourth generation formulas help in improvement of the accuracy of the calculation and decreasing the post operative refractive error. SRK/T formula showed the lowest mean error, however, there was not statistically significant difference between the three formulas used, neither in the overall performance, nor in axial length subcategories.