Prediction Error Stabilization and Long-Term Standard Results with a Monofocal Intraocular Lens

The aim of this study was to assess the stability and differences between objective (O-Rx) and subjective (S-Rx) refraction for the assessment of the prediction error (PE). A secondary aim was to report the results of a monofocal intraocular lens (IOL). 100 subjects were included for whom S-Rx and O-Rx were obtained for all visits, and for visual performance, posterior capsular opacification incidence and Nd:YAG rates at 12 months. Either S-Rx and O-Rx showed a hyperopic shift from 1 to 6 months (p < 0.05) and stabilization after 6 months. S-Rx was related with the axial length (rho = −0.29, p = 0.007), obtaining a major tendency towards hyperopia in short eyes implanted with high-power IOLs. O-Rx showed a myopic shift in comparison to S-Rx (p < 0.05). This resulted in a decrease of the number of eyes in ±0.50 D and ±1.00 D from 79 to 67% and from 94 to 90%, respectively. The median (interquartile range) uncorrected and corrected visual acuities were 0.1 (0.29) and 0 (0.12) logMAR, respectively, and seven eyes required Nd:YAG capsulotomy at 12 months. Some caution should be taken in PE studies in which O-Rx is used or S-Rx is measured in a 1-month follow-up. Constant optimization should be conducted for this IOL after S-Rx stabilization.

Phacoemulsification and calculation of intraocular lenses in patients given keratorefractive surgery. Part 2

Effective rehabilitation of patients with cataracts who underwent keratorefractive surgeries requires that the optical power of the IOL be calculated correctly to avoid hyperopic error. The purpose of the 2nd part of the research (for the 1st part, see ROJ, 2021; 14 (2): 55–58) is to present the results of cataract phacoemulsification in patients subjected to keratorefractive surgery based on the author’s algorithm for calculating the optical power of the IOL. Material and methods. The algorithm used optical biometry with an IOL-Master device. The main technique of improving the accuracy of IOL calculation after keratorefractive operations has been to introduce amendments to standard IOL calculation formulas. This work proposes an alternative, which consists in using the Hoffer Q formula, as it is more consistent with changes in the anterior segment of the myopic eye after keratorefractive surgery than other basic. The main distinguishing feature of the Hoffer Q formula is that the corneal refraction is not converted into the radius of curvature but is applied directly as the optical power of a “thin lens”. Results. The empirical customized correction was +1.0 D with regard to the estimated planned postoperative refraction (for patients with initial myopia from -3 to -9 D). The use of the “thin lens” principle made it possible to extrapolate this formula and apply it after LASIK surgery and after radial keratotomy. Conclusion. The proposed technique of IOL calculation was implemented for cataract phacoemulsification in over 200 patients who underwent keratorefractive surgeries. No cases of hyperopic shift of postoperative refraction were noted. The deviation from the planned myopic refraction did not exceed 1.0 D.

Long-term visual, anterior and posterior corneal changes after crosslinking for progressive keratoconus

Aim To evaluate the long-term outcomes of corneal cross-linking (CXL) in patients with progressive keratoconus. Method In this retrospective non-comparative study, forty-five eyes of 31 patients with progressive keratoconus were treated with 30 min “epi-off” corneal cross-linking. The visual, refractive, topographic and tomographic outcomes were evaluated preoperatively and at least 10 years after cross-linking. Results Ten years post-corneal cross-linking, the mean anterior maximum keratometry decreased (−2.10 ± 3.25 D, P = 0.0001). Conversely, the posterior maximum keratometry increased (6.38 ± 9.79 D, P = 0.065). Both uncorrected and corrected distance visual acuity improved (LogMAR −0.08 ± 0.30) and (LogMAR −0.05 ± 0.21), respectively (P > 0.05, both). A statistically significant hyperopic shift was observed postoperatively (0.70 ± 1.31 D, P = 0.0009). The anterior topographic cylinder values revealed no change (−0.17 ± 1.31 D, P = 0.3), whereas the mean posterior cylinder values decreased (absolute value increased) significantly compared to baseline from −1.31 ± 0.97 D to −1.82 ± 1.78 D, (P < 0.05). The minimum corneal thickness values decreased significantly (−35.11 ± 48.63 µm, P = 0.0001). Four eyes (8.8%) showed more than 1 D increase in the anterior maximum keratometry. Conclusion This protocol and duration of Epi-off corneal cross-linking was found to be effective in halting keratoconus progression over the follow up period (10 years). Anterior corneal flattening and a hyperopic shift were observed. A statistically significant increase in the posterior corneal cylinder was observed. Although, not reaching statistical significance, the logMAR uncorrected and corrected visual acuity were improved.

Correlation between one month post operative refractive status with pre operative calculated IOL power

To study the correlation between preoperative calculated IOL power and post operative refractive error in temporal phacoemulsification. This study was a retrospective analysis in which data of 100 cases of senile cataract who underwent temporal phacoemulsification with foldable IOL was selected. Patients underwent post op examination at 4 weeks and only those patients whose vision was improving to 6/6 with or without correction was selected and their post operative refractive error in form of spherical equivalent was evaluated at 4 weeks of surgery and analysed with the preoperative calculated IOL power. All complicated cataract, cases with ocular pathology, patient with intraoperative or post operative complication and patient with history of any ocular surgery were excluded from the study. Formula used were SRK/T, HOFFER Q and HAIGIS.The mean IOL power used was20.39± 4.91, mean axial length was 23.43±1.53. The mean refractive error in form of spherical equivalent was-0.32±0.74. A total of 84 percent patients refractive error was upto 1D.A total of 37 percent patient had refractive error upto 0.25D, 57 percent upto 0.50 and 72 percent upto 0.75D.Myopic shift was present in 53 percent patients and hyperopic shift in 24 percent patient. There was no statistically significant correlation between iol power and refractive error at 4 week of temporal phacoemulsification as p value came as p=0.34While pre op accurate calculation of IOL power is very important for better visual acuity post op but just looking at any IOL power we cannot guess about refractive error that it may result.

Five-year change in refractive error and its risk factors: results from the Gutenberg Health Study

Background/AimsTo examine the 5-year change in refractive error in phakic eyes and its risk factors in the general population.MethodsThe Gutenberg Health Study (GHS) is a population-based cohort study including 15 010 participants from Germany aged 35–74 years at baseline examination (2007–2012). After 5 years, a follow-up examination was carried out (83% participation). 5-year change of spherical equivalent (SE) was computed as difference between follow-up and baseline objective refraction. Linear and logistic regression analysis were conducted analysing potential risk factors. Only phakic eyes at follow-up examination were included.ResultsRight eyes of 10 175 subjects were included. An age-related shift of refractive error was identified, namely −0.12 D for age 35–44 years, 0.25 D for age 45–54 years, 0.25 D for age 55–64 years and 0.12 D for age 65–74 years during the 5-year follow-up. Smokers had a hyperopic shift (OR=1.31; p<0.001), while baseline SE (OR=0.89 per dioptre; p<0.001) and female sex (OR=1.49; p<0.001) were linked with a myopic shift. Education, occupation and other cardiovascular parameters were not associated with change in refractive error.ConclusionsThe GHS demonstrates a parabolic shift in refractive error with a myopic shift at age 35–44 years, followed by a hyperopic shift at age 45–64 years which decreases at higher age. Smoking is associated with a hyperopic shift whereas female sex and myopic baseline SE is associated with a myopic shift. Educational level and occupation were not linked to a change in refractive error at age 35–74 years.

Intraocular lens power calculation for plus and minus lenses in high myopia using partial coherence interferometry

Purpose We assessed the accuracy of lens power calculation in highly myopic patients implanting plus and minus intraocular lenses (IOL). Methods We included 58 consecutive, myopic eyes with an axial length (AL) > 26.0 mm, undergoing phacoemulsification and IOL implantation following biometry using the IOLMaster 500. For lens power calculation, the Haigis formula was used in all cases. For comparison, refraction was back-calculated using the Barrett Universal II (Barrett), Holladay I, Hill-RBF (RBF) and SRK/T formulae. Results The mean axial length was 30.17 ± 2.67 mm. Barrett (80%), Haigis (87%) and RBF (82%) showed comparable numbers of IOLs within 1 diopter (D) of target refraction. Visual acuity (BSCVA) improved (p < 0.001) from 0.60 ± 0.35 to 0.29 ± 0.29 logMAR (> 28-days postsurgery). The median absolute error (MedAE) of Barrett 0.49 D, Haigis 0.38, RBF 0.44 and SRK/T 0.44 did not differ. The MedAE of Haigis was significantly smaller than Holladay (0.75 D; p = 0.01). All median postoperative refractive errors (MedRE) differed significantly with the exception of Haigis to SRK/T (p = 0.6): Barrett − 0.33 D, Haigis 0.25, Holladay 0.63, RBF 0.04 and SRK/T 0.13. Barrett, Haigis, Holladay and RBF showed a tendency for higher MedAEs in their minus compared to plus IOLs, which only reached significance for SRK/T (p = 0.001). Barrett (p < 0.001) and RBF (p = 0.04) showed myopic, SRK/T (p = 002) a hyperopic shift in their minus IOLs. Conclusions In highly myopic patients, the accuracies of Barrett, Haigis and RBF were comparable with a tendency for higher MedAEs in minus IOLs. Barrett and RBF showed myopic, SRK/T a hyperopic shift in their minus IOLs.

Comparison of Five Intraocular Lens Power Formulas to Predict Postoperative Refraction Accuracy

The present study sought to investigate and compare the accuracy of two third-generation intraocular lens calculation formulas contrasted against three new-generation intraocular lens calculation formulas regarding their ability to predict postoperative refraction following cataract surgery. A retrospective case study following 172 patients (172 eyes) exhibiting age-related cataracts in their eyes who were subject to phacoemulsification between September 2017 and September 2018 at the Department of Cataracts, Tianjin Medical University Eye Hospital, was carried out. Based upon ocular axial length, the sampled patients were grouped into a short axis group (ocular axial length ≤ 22 mm; 17 cases; 17 eyes), a normal axis group (22 mm < ocular axial length ≥ 24.5 mm; 132 cases; 132 patients), and a long axis group (ocular axial length > 24.5 mm; 23 cases; 23 eyes); mean absolute prediction error (MAE) postoperative refraction in each group was determined using five formulas, and the percentage of eyes displaying postoperative myopic shift symptoms, postoperative hyperopic shift symptoms, alongside the percentage of eyes displaying postoperative refractive shift symptoms in the range of (−0.25 to 0.25 D, −0.50 to 0.50 D, −1.00 to 1.00 D), were all calculated following the procedures of the five selected formulas. The MAE of the 172 patient cases was compared within the five selected formulas, and SRK/T possessed the highest prediction accuracy, exhibiting a significant difference from the other four formulas (P < 0.05), with accuracy levels subsequently followed by the Holladay 1 and Barrett Universal II formulas-however, the two formulas lacked a significant difference between them (P > 0.05). In addition, the MAE of the normal axial group was compared and analyzed within the five formulas, with analysis revealing that the SRK/T, Holladay 1, and Barrett Universal II formulas exhibited strong prediction accuracy, with no significant difference present among these three formulas (P > 0.05), and also revealing a significantly difference between the aforementioned formulas and remaining two formulas (P < 0.05). For further analysis, the MAE of the short axis group was compared, and the SRK/T and Haigis (Holladay 1, and Barrett Universal II) demonstrated stronger prediction accuracy when compared to the Olsen formula (P < 0.05). Finally, the MAE of the long axis group was compared, and it was found that the SRK/T and Barrett Universal II formulas exhibits the best prediction accuracy, followed by the Haigis and Holladay 1 formulas, with no significant difference (P > 0.05) between the former two formulas or the latter two. The majority of patients exhibited hyperopic shift post-surgery. Of the five formulas studied, the SRK/T and Barrett Universal II formulas possessed strong accuracy capable of predicting postoperative refraction. However, more long-term observation, including large patient samples, is necessary in order to corroborate our result.

Post-operative optical coherence tomography angiography features of chorioretinal folds resulting from pleomorphic adenoma of the lacrimal gland (PALG) of orbit- a case report

Background Chorioretinal fold (CFs) is a rare condition resulting from undulations in the choriocapillaris, Bruch's membrane, retinal pigment epithelium and occasionally neurosensory retina. It can be idiopathic or due to different etiologies. The use of spectral-domain optical coherence tomography (SD-OCT) has increased the diagnosis of CFs and helped in differentiation from other etiologies. Recently, optical coherence tomography angiography (OCT-A) emerged as a non-invasive imaging technique allowing visualization of the individual layers of microvasculature of the retina and the choroid by comparing consecutive B-scans. We described a rare case of pleomorphic adenoma of the lacrimal gland (PALG) causing hyperopic shift and CFs with the new OCT-A technology, getting deeper insight into vascular changes of this disease. Case presentation A 40-year-old Asian man experienced progressive blurred vision in his right eye over 6 months. The patient’s initial axial lengths were 25.55 mm in the right eye and 28.13 mm in the left eye. Fundus examination in the right eye revealed oblique CFs as well as the SD-OCT displayed. Magnetic resonance imaging showed intraconal mass extended from superior temporal side of the right orbit. The patient then received tumor removal surgery through lateral orbitotomy and histopathology confirmed a pleomorphic adenoma of the orbit. The patient had regular follow-up for 1 year. His best corrected visual acuity markedly improved from 20/50 to 20/20 with nearly stationary AXL. We performed OCT-A at one year after the surgery, which showed early visualization of deep choroidal vessels. The scleral remodeling due to mass effect of retrobulbar tumor also caused displacement of the deep large choroidal vessels over the superior macular area even after tumor removal. Conclusions We reported a rare case of PALG with hyperopic shift and CFs as initial presentation. Surgical removal of the tumor partially resolved the CFs and contributes to impressive visual acuity recovery. The use of OCT-A provided a deeper insight to vascular architecture changes resulting from scleral remodeling after long-term tumor compression.

Comparison of aphakic refraction and biometry-based formulae for secondary in-the-bag and sulcus-implanted intraocular lens power estimation in children

Purpose: To compare the accuracy of refractive outcomes in children undergoing secondary in-the-bag or cilliary sulcus IOL implantation, using aphakic refraction (AR)-based formulae and biometry-based formulae. Methods: In this retrospective study, 39 eyes of the in-the-bag IOL group and the other 26 eyes of the sulcus-implanted IOL group. Holladay 1, Hoffer Q, SRK/T and SRK II formulae were employed depending on the biometric data, while Hug and Khan formulae were used based on preoperative aphakic refraction. The prediction error (PE) and the absolute value of predicted error (APE) were compared between the two groups and formulae. Results: In the in-the-bag IOL group, non-significant differences of APE were found among the 6 formulae, while the Holladay 1, Hoffer Q, SRK/T and SRK II all demonstrated a significant hyperopic shift of median PE value compared to the Hug formula and Holladay 1 and SRK II also showed a significant hyperopic shift of PE compared to the Khan . Higher percentages of eyes with PE less than 1 D were found using Hoffer Q and SRK/T. In the sulcus-implanted group, the Holladay 1, Hoffer Q and SRK/T had a significantly smaller median value of APE than the Hug and Khan formulae, and the SRK II had a significantly smaller median value of APE than the Hug formula, while Holladay 1 had the lowest value of APE. Higher percentages of eyes within PE less than 1 D were found using Holladay 1, Hoffer Q and SRK/T, while the highest was SRK/T. Significantly larger hyperopic shifts of median PE value using all the 6 formulae were found in eyes with sulcus-implanted IOL than with in-the-bag implanted IOL . In in-the-bag implanted IOL group, the Hug and Khan formulae had significantly smaller APE values when compared with the sulcus-implanted IOL group. Conclusions: whether IOL was in the bag or sulcus implantation, almost all the formulae showed hyperopic shift, SRK/T showed the best accuracy. Biometry-based formulae were superior to AR-based formulae in accuracy of IOL power calculation, especially when IOL was implanted in the sulcus. In-the-bag IOL implantation should always be with higher priorities, especially when using AR-based formulae in IOL power calculation.

Effect of capsular tension ring on refractive results in cases with pseudoexfoliation syndrome

Purpose: To investigate the effect of capsular tension rings (CTRs) on postoperative refractive results in patients with pseudoexfoliation (PSX) syndrome. Materials and Methods: Sixty-nine patients with PSX syndrome who had uncomplicated cataract surgery between March 2016 and February 2019 were reviewed retrospectively. The patients were divided into two groups. The 35 patients in Group 1 received CTRs prior to intraocular lens implantation during cataract surgery, and the 34 patients in Group 2 had cataract surgery without CTRs. Significant zonular weakness, uncontrolled glaucoma, and ocular pathologies causing low visual acuity were excluded. The preoperative and postoperative keratometry and autorefraction measurements, preoperative expected refractive values, and absolute refractive error were recorded. Results: The mean ages of patients were 73.54 ± 9.78 years in Group 1 and 72.23 ± 6.72 years in Group 2 ( p = 0.521). There was no statistically significant difference between Group 1 and Group 2 in terms of expected preoperative refraction values (–0.52 ± 0.12,–0.56 ± 0.08, respectively, p = 0.118). There was a statistically significant difference in postoperative spherical equivalent values between Group 1 and Group 2 (–0.05 ± 0.97 and −0.92 ± 0.57, respectively, p < 0.01). A statistically significant difference was found between the two groups in terms of absolute refractive error (0.46 ± 0.74 in Group 1 and −0.34 ± 0.59 in Group 2 p < 0.01). Conclusion: CTR implantation causes hyperopic shift, which should be taken into consideration when calculating the lens power of intraocular lens in patients with PSX syndrome.