Medium Axial Length Research Articles

Accuracy of the Majority Voting Method with Multiple IOL Power Formulae.

This study aimed to evaluate the efficacy of a majority decision algorithm that integrates intraoperative aberrometry (IA) and two intraocular lens (IOL) frequency formulas. The primary objective was to compare the accuracy of three formulas (IA; Sanders, Retzlaff, and Kraff/Theoretical (SRK/T); and Barrett Universal II (BUII)), in achieving emmetropia in eyes implanted with TFNT lenses (Alcon). A total of 145 eyes of 145 patients were included in the evaluation. Preoperative data were obtained from IOLMaster 700, while intraoperative data were collected from ORA SYSTEMTM. Visual acuity ≥0.8 at the 3-month post-surgery mark was confirmed. We assessed refractive prediction error (RPE), which is the difference between predicted refraction (PR) and postoperative subjective refraction. This evaluation aimed to identify the optimal IOL power with the implemented algorithm. Among the 145 eyes evaluated, 55.9%, 78.7%, and 97.2% achieved postoperative subjective refraction within ±0.13 Diopters (D), ±0.25 D, and ±0.50 D, respectively. The percentages of eyes within ±0.25 D of PR varied by formula type, with values of 57%, 57%, and 54% for IA, BUII, and SRK/T, respectively. For eyes with short to medium axial length (AL<26.00 mm), the percentages within ±0.25 D of RPE were 52%, 58%, and 58% for IA, SRK/T, and BUII, respectively. In contrast, for eyes with long axial length (≥26.00 mm) the percentages were 68%, 52%, and 45% for IA, BUII, and SRK/T, respectively. The proposed majority decision algorithm incorporating IA and two IOL frequency formulas was effective in reducing postoperative refractive error. IA was particularly beneficial for eyes with long axial length. These findings suggest the algorithm has potential to optimize IOL power selection to improve quality of life of patients and clinical practice outcomes.

Quantitative analysis of dynamic iris changes in primary angle-closure disease with long axial lengths: the Handan Eye Study.

To investigate dynamic iris changes in patients with primary angle-closure disease (PACD) with long axial length (AL) compared to those with short and medium AL. This observational cross-sectional study enrolled participants aged 35 years or older from the Handan Eye Study follow-up examination who were diagnosed with PACD and underwent Visante anterior segment optical coherence tomography (ASOCT) imaging under light and dark conditions. The right eye of each participant was included in the analysis. AL was categorized as short (<22.0 mm), medium (≥22.0 to ≤23.5 mm), or long (>23.5 mm). Anterior segment parameters, including iris dynamic changes, were compared among the three groups with different ALs. Data from 448 patients with PACD were analyzed. We found that 10.9% of included eyes had a long AL with a flatter cornea; larger central anterior chamber depth, angle opening distance, anterior chamber width, anterior chamber area, and volume; and smaller lens thickness and lens vault (LV) (P < 0.05) than those with short AL. No significant difference existed between the three groups in iris thickness, iris cross-sectional area (IA), iris curvature, or pupil diameter (PD) change between light and dark (P > 0.05). The significant associated factors for IA changes were area recess area (ARA) in the dark, LV in the dark, and PD change from light to dark (P < 0.05). Dynamic and static iris parameters were consistent across patients with PACD with short, medium, or long AL and may contribute to the pathogenesis of angle closure in atypical PACD.

Refractive outcomes of second-eye adjustment methods on intraocular lens power calculation in second eye.

To investigate the refractive outcomes of second-eye adjustment (SEA) methods in different intraocular lens (IOL) power calculation formulas for second eye following bilateral sequential cataract surgery. This retrospective consecutive case-series study included 234 eyes from 234 patients who underwent bilateral sequential phacoemulsification and implantation of enVista MX60 in a hospital setting. Postoperative refraction outcomes calculated by standard formulas (SRK/T and Barrett Universal II, BUII) with SEA method were compared with those calculated by an artificial intelligence-based IOL power calculation formula (PEARL DGS) under second eye enhancement (SEE) method. The median absolute error (MedAE), mean absolute error (MAE) and percentage prediction errors (PE) of eyes within ±0.25 diopters (D), ±0.50 D, ±0.75 D and ± 1.00 D were determined. Overall, the improvement in MedAE after SEA was significant for PEARL DGS (p < 0.01), SRK/T (p < 0.001) and BUII (p=0.031), which increased from 74.36, 71.37, and 77.78% to 83.33, 80.34, and 79.49% of eyes within a PE of ±0.50 D, respectively. For first eyes with a medium axial length (22-26 mm), PEARL DGS with SEE had the lowest MedAE (0.21 D). For a first-eye MAE over 0.50 D, SEA method led to significant improvement in the second eye (p < 0.01). Interocular axis length differences exceeding 0.3 mm were associated with weaker effects using SEA in the studied formulas (p > 0.05). Either SEA method with SRK/T and BUII formulas or second-eye enhancement method based on the PEARL DGS formula can improve postoperative refractive outcomes in second eye.

Recurring themes during cataract assessment and surgery.

The aim of this review was to discuss frequently encountered themes such as cataract surgery in presence of age-related macular degeneration (AMD), dementia, Immediate Sequential Bilateral Cataract Surgery (ISBCS), discussing non-standard intraocular lens (IOL) options during consultation in the National Health Services (NHS) and the choice of the biometric formulae based on axial length. Individual groups of authors worked independently on each topic. We found that cataract surgery does improve visual acuity in AMD patients but the need for cataract surgery should be individualised. In patients with dementia, cataract surgery should be considered 'sooner rather than later' as progression may prevent individuals presenting for surgery. This should be planned after discussion of patients' best interests with any carers; multifocal IOLs are not proven to be the best option in these patients. ISBCS gives comparable outcomes to delayed sequential surgeries with a low risk of bilateral endophthalmitis and it can be cost-saving and efficient. Patients are entitled to know all suitable IOL options that can improve their quality of life. Deliberately withholding this information or pressuring patients to choose a non-standard IOL is inappropriate. However, one should be mindful of the not spending inappropriate amounts of time discussing these in the NHS setting which may affect care of other NHS patients. Evidence suggests Hoffer Q, Haigis, Hill-RBF and Kane formulae for shorter eyes; Barrett Universal II (BU II), Holladay II, Haigis and Kane formulae for longer eyes and BU II, Hill-RBF and Kane formulae for medium axial length eyes.

Intraocular lens power calculation formula accuracy: Comparison of 12 formulas for a trifocal hydrophilic intraocular lens.

To evaluate the accuracy of 12 intraocular lens (IOL) power formulas; Barrett Universal II, Emmetropia Verifying Optical (EVO), Haigis, Hill-Radial Basis Function (RBF), Hoffer Q, Holladay I, Kane, Ladas Super Formula, Olsen Lenstar, Panacea, Pearl-DGS, Sanders-Retzlaff-Kraff/theoretical (SRK/T). In addition, an analysis of the efficacy as a function of the axial length was performed. About 171 from 93 patients: 68 male eyes and 103 female eyes. Twelve IOL power formula calculations were studied with one IOL platform (trifocal hydrophilic IOL, FineVision Micro F), one biometer (Lenstar LS 900), one topographer (CSO Sirius Topographer), one surgeon, and one optometrist. Optimization were determined to be zeroed mean refractive prediction error. Mean error (ME), mean absolute error (MAE), median absolute error (MedAE) and refractive accuracy within ±1.00 D was calculated. Axial length was split in short and medium eyes. One hundred and seventy eyes were included. Formulas were ranked by percentage within ±0.50 diopters and MAE (D). Among all eyes, Olsen 86.55% (0.273 D) and Barrett Universal II 86.55% (0.285D). For short eyes (<22.5 mm), Olsen 90.70% (0.273 D) and Kane 90.70% (0.225 D). For medium eyes, Barrett 89.34% (0.237 D) and Pearl 86.89% (0.263 D). Olsen and Barrett formula obtained excellent accuracy for overall eyes. Kane and Olsen formula obtained the best results in short eyes. For medium axial length Barrett formula achieved the best accuracy results.

Comparison of the Kane formula with existing formulas for intraocular lens power selection

ObjectiveTo compare the accuracy of a new intraocular lens (IOL) power formula (Kane formula) with existing formulas using IOLMaster, predominantly model 3, biometry (measures variables axial length, keratometry and anterior...

What Are the Characteristics of Primary Angle Closure With Longer Axial Length?

To compare biometric parameters between primary angle closure with longer axial length (AL) and those with medium or shorter AL. We prospectively recruited 138 primary angle-closure patients. Low-coherence interferometry and ultrasound biomicroscopy examinations were performed before laser peripheral iridotomy and pilocarpine treatment. AL was categorized as shorter (<22.5 mm), medium (≥22.5 to <23.5 mm), or longer (≥23.5 mm). Anterior chamber depth and width (ACD and ACW), lens vault (LV), anterior vault (AV), relative AV (AV/AL), relative lens position (RLP, [ACD + 1/2 lens thickness]/AL), trabecular-ciliary angle (TCA), keratometry, and other biometric parameters were compared among different AL groups. Among 138 angle-closure patients, 15 (10.9%) patients had longer ALs, of which 11 (73.3%) were male. These angle-closure eyes with longer AL had flatter cornea (P = 0.006 and 0.022 for flat and steep keratometry) and larger ACW (P = 0.006), but smaller RLP (P = 0.019) than those with medium AL; similarly, they had flatter cornea (P < 0.001 for both flat and steep keratometry), and larger ACW (P < 0.001), AV (P = 0.004), and TCA (P = 0.024), but smaller relative AV (P = 0.040) and RLP (P = 0.005) than those with shorter AL. No significant differences were found in the other parameters. Primary angle closure with longer AL was uncommon. Causes of angle closure in these atypical patients were manifold. These patients were predominantly male; they had smaller relative dimension of the anterior segment, flatter cornea, and more anterior RLP and less anteriorly rotated ciliary body compared with those angle-closure patients with relatively shorter AL.

Predicting the refractive outcome and accuracy of IOL power calculation after phacoemulsification using the SRK/T formula with ultrasound biometry in medium axial lengths.

PurposeTo evaluate the accuracy of the SRK/T formula using ultrasound (US) biometry in predicting a target postoperative refraction of ±1.00D in eyes with medium axial length (AL) that underwent phacoemulsification.MethodsThe present study was a retrospective analysis, which included 538 eyes with an AL from 22.0 to 24.60 mm that underwent phacoemulsification and foldable intraocular lens (IOL) implantation (six different IOLs) in the bag. Preoperative AL was measured by US biometry and IOL power (IOLp) was calculated with the SRK/T formula. Patients had a complete ophthalmic examination, preoperatively and 1, 7, and 30 days after surgery. The achieved spherical equivalent (SE) and the prediction error (PE) were calculated. The prediction error was defined as the difference between attempted predicted target refraction and the achieved postoperative SE refraction. Statistical analysis was performed with SPSS V21.ResultsThe mean age of the patients was 66.96±9.67 years, the mean AL was 23.29±0.62 mm, the mean K1 was 43.62±1.49D, the mean K2 was 43.69±1.53D, the mean IOL power was 21.066±1.464D, the mean attempted (predicted) SE was −0.178±0.266D, and the mean achieved SE was −0.252±0.562D. The mean PE (difference between predicted and achieved SE) showed a relatively hyperopic shift (mean ± standard deviation: 0.074±0.542D, ranging from −1.855 to 2.170D, P=0.001). A total of 93.87% of eyes were within ±1.00D of the PE and 92.75% of eyes within ±1.00D of achieved postoperative refraction. A total of 39 eyes (7.25%) had a refractive surprise. A total of 32 of 39 eyes were more myopic than −1.00D and 7 of them were more hypermetropic than +1.00D. There was no correlation between the mean PE and IOL type, AL, K1, K2, and IOLp. There were a positive statistically significant correlation between PE and age (r=0.095; P=0.028) and a negative statistically significant correlation between achieved SE and AL (Spearman’s r=−0.125; P=0.04), and age (r=−0.141; P=0.01).ConclusionThe IOLp calculation using the SRK/T formula with US biometry may demonstrate very good postoperative refractive outcomes in medium eyes with a few refractive surprises.

Clinical results in phacoemulsification using the SRK/T formula

To evaluate the prediction of refraction using the SRK/T formula for intraocular lens (IOL) calculation in eyes with medium axial length after phacoemulsification. This prospective study enrolled 33 eyes with nuclear cataract that underwent phacoemulsification. All procedures were performed by one surgeon with the intraocular lens placed within the capsular bag. The same technician who was unaware of the purpose of the study made all the measurements. The achieved refractive error one month after surgery was compared to the predicted postoperative refractive error by the SRK/T formula. The ocular axial length varied between 22.2 mm and 24.5 mm. The mean predicted refraction was -0.431 +/- 0.181 D and the mean achieved postoperative spherical equivalent was -0.220 +/- 0.732 D. Eighteen eyes (55%) had a refractive error between +/- 0.50 D and thirty eyes (91%) between +/- 1.00 D of the predicted refraction. There was a tendency toward hyperopic shift (mean +/- SD: 0.211 +/- 0.708 D, p=0.009). The SRK/T formula demonstrated a satisfactory accuracy to calculate the error of refraction in eyes with medium axial length.