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Lens and cataract
Clinical science
Cataract surgery in the extremely small eye: morphology, comorbidities and outcomes in 300 eyes
  1. Maximilian Hammer1,2,
  2. Lilly Teich1,2,
  3. Maximilian Friedrich1,2,
  4. Emanuel Reitemeyer2,
  5. Leoni Britz1,2,
  6. Ramin Khoramnia2,
  7. Timur Mert Yildirim1,2,
  8. Gerd U Auffarth1,2
  1. 1 David J Apple Laboratory for Vision Research, Heidelberg, Germany
  2. 2 Heidelberg University Hospital Department of Ophthalmology, Heidelberg, Germany
  1. Correspondence to Professor Gerd U Auffarth; gerd.auffarth{at}med.uni-heidelberg.de

Abstract

Background/aims Data on morphological characteristics and outcomes of extremely short eyes undergoing cataract surgery is sparse. Thus, an in-depth characterisation of eyes implanted with a high-power intraocular lens (IOL) (>30 dioptres) was performed.

Methods In this retrospective cohort study from January 2009 to October 2023, 300 eyes of 191 patients undergoing cataract surgery with extremely short axial length requiring the implantation of a high power IOL>30D were included. Eyes were categorised into the morphologies of nanophthalmos (N), relative anterior microphthalmos (RAM) and high or low/moderate hyperopia (HH and MH). Comorbidities, intraoperative and postoperative complications, preoperative and postoperative refraction and visual outcomes were investigated.

Results Mean preoperative spherical equivalent (SE) was +6±2.85 D. The mean axial length was 20.68±0.92 mm. 19.3%, 45.3%, 22.7% and 12.7% of the studied eyes were categorised as MH, HH, N and RAM, respectively. Amblyopia (14.7%), previous strabismus surgery (7.3%), glaucoma (12.7%) and previous iridotomy (9.4%) were prevalent. Postoperative SE was −0.42±1.56 D. Preoperative Corrected Distance Visual Acuity (CDVA) and postoperative Uncorrected Distance Visual Acuity (UDVA) were not significantly different (0.34±0.39 Logarithm of the Minimum Angle of Resolution (logMAR) vs 0.47±0.38 logMAR, respectively, p=0.47), postoperative CDVA was slightly improved (0.28±0.31 logMAR, p=0.02). The narrow anterior chamber angle was significantly alleviated, posterior capsule rupture rates (3%) were within previously reported ranges.

Conclusions Lens surgery is safe, improves the anterior chamber situation but is rather imprecise in extremely short eyes. Of all subtypes, nanophthalmic eyes showed compromised outcomes. Postoperative CDVA is only slightly improved to preoperative CDVA, while postoperative UDVA closely resembles preoperative CDVA. Surgery thus provides spectacle independence leading to good patient satisfaction.

  • Epidemiology
  • Ophthalmological Surgical Procedures
  • Anterior chamber
  • Lens and zonules

Data availability statement

Data are available upon reasonable request. The datasets generated and analysed during the current study are not publicly available, but are available from the corresponding author upon reasonable request.

http://creativecommons.org/licenses/by-nc/4.0/

This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.

https://doi.org/10.1136/bjo-2024-326998

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    WHAT IS ALREADY KNOWN ON THIS TOPIC

    • High-power intraocular lenses are implanted in extremely short eyes. Data on their morphology, ocular comorbidities, intraoperative and postoperative complications and outcomes are sparse.

    WHAT THIS STUDY ADDS

    • 19.3%, 45.3%, 22.7% and 12.7% of the studied eyes were categorised as moderately hyperopic, highly hyperopic, nanophthalmic and as relative anterior microphthalmos, respectively. Amblyopia, strabismus and glaucoma were highly prevalent. While cataract surgery was safe, refractive surprises were common. The shallow anterior chamber angle situation was alleviated through surgery. Preoperative Corrected Distance Visual Acuity resembles postoperative Uncorrected Distance Visual Acuity.

    HOW THIS STUDY MIGHT AFFECT RESEARCH, PRACTICE OR POLICY

    • The findings of this biggest cohort to date allow a better preoperative management of patient expectation.

    Introduction

    The prevalence of high hyperopia (HH) with an extremely short axial length (AL) in the general population is around 1–2%.1 2 Compared with high myopia, morphological data and outcomes for this patient population undergoing cataract surgery are sparse. Further, extremely short eyes often presenting with a highly hyperopic refraction can be categorised into HH (posterior microphthalmos), relative anterior microphthalmos (RAM) and nanophthalmos (N) based on their AL, anterior chamber depth, corneal diameter and refraction.3 4

    For short eyes, one aspect that all of these morphologies share is that these eyes may require high-power intraocular lenses (IOLs)5 for capsular bag implantation or treatment with a polypseudophakic approach.6 High-power IOLs are defined as IOLs with a power of 30 dioptres or more. These IOLs hold inherent downsides like a higher manufacturing tolerance of ±1 dioptres,7 limited availability and an increased inaccuracy in the effective lens position and thus in biometry.8

    Combined with a shallow anterior segment, outcomes of cataract surgery in this patient collective have been reported to be worse and less predictable than in an emmetropic cohort.9 However, previous studies have either not differentiated between the abovementioned morphologies, included only a small number of eyes,10 or have exclusively focused on certain aspects of cataract surgery, such as IOL calculation.10 11 During the last two decades, few studies with a moderate cohort size at best have dealt with this patient population. Thus, the purpose of this study was to better define the morphology of cases receiving high-power IOLs from a real-world data set of tertiary care ophthalmology department with a specialisation on complex lens surgery. By conducting these in-depth analyses, surgeons can better set expectations in these complex cases. Thus, IOL choices, intraoperative and postoperative complications, visual and refractive outcomes as well as morphological changes in a subgroup of patients were collected and analysed.

    Methods

    Study design and ethical approval

    In this study, we analysed cases undergoing cataract surgery or refractive lens exchange surgery at the University Eye Clinic Heidelberg between January 2009 and December 2023. The study site is a centre for complicated lens surgery. The study used de-identified data from a database of 25 586 performed cataract surgeries.

    Patient selection

    All eyes undergoing lens surgery were screened. We included adult patients undergoing cataract or refractive lens surgery with implantation of a high-power IOL of 30D or more. Cases with missing biometry data and cases with an aphakic or pseudophakic lens status (eg, revision surgeries, IOL subluxations) were excluded.

    Surgical procedure

    Patients underwent lens surgery using clear corneal incision. Surgeries were performed by one of five experienced surgeons. Following the aspiration of the crystalline lens using the phaco tip and subsequently a bimanual aspiration and irrigation system, the IOL was implanted into the capsular bag. In case of toric IOLs, the lens was aligned using manual markers or with the assistance of the VERION System (Alcon, USA) or with the Callisto system (Carl Zeiss Meditec, Jena, Germany). For all patients, Haigis, SRK/T and Holladay II were calculated and were reviewed for agreement. Modern formulas (such as Kane) were not available at the time of surgery for most cases. Patients underwent an intraocular pressure measurement using Goldman applanation tonometry on postoperative day 1.

    Data collection

    Data was collected from the hospital-governed databases comprising surgery-related and patient-related data. Preoperative morphological features were retrieved from the local database of the IOLMaster 700 and IOLMaster 500, optical coherence tomography (OCT) data and analysis were retrieved from the HEYEX Platform (Heidelberg Engineering, Heidelberg, Germany), data on corneal topography and the anterior chamber angle was retrieved from the Scheimpflug tomography (various models of the Pentacam, Oculus Optikgeräte, Wetzlar, Germany). OCTs were only performed postoperatively when a macular pathology (eg, a newly developed cystoid macular oedema) was suspected.

    Morphological categorisation

    Eyes were categorised into four groups based on their morphology: moderate hyperopia (MH), HH, N and RAM. All eyes with an AL<20 mm were categorised as nanophthalmic eyes.12 13 Eyes with an anterior chamber depth <2.2 mm or a corneal diameter <11 mm but an AL>20 mm were defined as relative anterior micropthalmos.3 Eyes with a preoperative refraction of >5 D, an AL>20 mm and an anterior chamber depth >2.2 mm and a corneal diameter >11 mm were defined as HH as suggested by the American Academy of Ophthalmology. The majority of eyes not classified as described above were moderately hyperopic and therefore defined as ‘moderate hyperopia’. The anterior chamber angle was determined based on Scheimpflug tomography data for every quadrant (various models of the Pentacam, Oculus Optikgeräte GmbH, Wetzlar, Germany).

    Visual acuity

    Visual acuity values were translated from decimal to logMAR. Hand movement and counting fingers were converted to logMAR using a previously used transcription used by the National Ophthalmology Database.14 15 Counting fingers was thus equivalent to logMAR 2.1, hand movement to 2.4 and light perception to 2.7. The last visual acuity was defined as the visual acuity value recorded furthest past the surgery date. Only values 7 days or more after surgery were considered.

    Sensitivity analysis

    We performed various sensitivity analyses to assess the robustness of our results. (1) Effects on visual acuity were also assessed in a patient cohort with available postoperative data on best corrected visual acuity 1 month or more after surgery. (2) Eyes with diagnosed amblyopia were excluded and primary analysis were reconducted.

    Statistical analyses

    Analyses were predefined in a statistical analysis plan, which was approved by all authors before commencing. All statistical analyses were performed using Stata V.17 BE (StataCorp, College Station, Texas, USA). Mixed effect models were used to account for the possible influence of including both eyes of a patient. Graphics were designed using Prism GraphPad Software, Boston, USA.

    Results

    Patient characteristics and morphology

    Figure 1 depicts the study flow. Of 25 586 cataract surgeries performed at the University Eye Clinic Heidelberg, 313 were implanted with a high-power IOL. After exclusion of cases with missing preoperative biometry data, pseudophakic lens status or aphakic lens status prior to surgery, the final study cohort comprised 300 eyes of 191 patients. In this cohort, a very high comorbidity rate of glaucoma (eg, nearly a quarter of all nanophthalmic eyes) and previous strabismus surgery of 7.33% (22 of 300 cases was present).

    Figure 1
    Figure 1

    Study flow. Of 25 586 cataract surgeries, 313 cases were implanted with a high power IOL. 13 cases were excluded due to missing biometry data or pseudo- or aphakic lens status. This results in a primary cohort of 300 eyes from 191 patients. IOL, intraocular lens.

    Morphological data

    Figure 2A showcases the morphological data of this patient population. The average AL was 20.68±0.92 mm. 58 cases can be classified as MH, 136 cases as HH, 68 as N and 38 as RAM. Corneal power averaged at 43.6 D and therefore close to the emmetropic population, which has been previously reported at around 43.5 D.16

    Figure 2
    Figure 2

    Morphology of the studied population. (A) Axial length, red line at 20 mm is the cut-off for nanophthalmic eyes, dotted line depicts the previously reported mean axial length in a representative population.31 Anterior chamber depth, red line at 2.2 mm is the cut-off for relative anterior microphthalmos, dotted line depicts a previously reported mean anterior chamber depth in a representative population.31 Corneal diameter, red line at 11 mm is the cut-off for relative anterior microphthalmos. Dotted line depicts a previously reported mean anterior chamber depth in a respective population.32 Corneal power, dotted line depicts a previously reported mean anterior chamber depth in a respective population.31 (B) Preoperative and postoperative anterior chamber angle. A significant increase in the anterior chamber angle was observed in all quadrants.

    Preoperative and postoperative comparison of anterior chamber morphology

    Further, in patients with available preoperative and postoperative Scheimpflug tomography imaging (n=49), we analysed the impact of cataract surgery on the anterior chamber angle in every quadrant. Surgical intervention significantly increased the chamber angle in all quadrants (figure 2B).

    Preoperative ocular comorbidities and indication for cataract surgery

    44 eyes (14.7%) were amblyopic. 7.3% of the study eyes had undergone previous strabismus surgery prior to cataract surgery. Previous corneal surgery, refractive surgery, vitrectomy, lid surgery as well as indication for intravitreal therapy were rare (see table 1).

    View this table:
    Table 1

    Patient cohort characteristics

    Glaucoma prevalence with 12.7% was elevated in our study population compared with population-based values for a Caucasian population at 70 years of age with 4.8% as presented by Johansson et al.17 While previous filtrating surgery and angle surgery were uncommon (1% of study population), 9.4% of the study population had undergone an iridotomy prior to cataract surgery. As to be expected, the two morphologies with a small anterior segment, namely N and RAM, had the highest preoperative iridotomy rates (13.2% and 26.3%, respectively). This is further reflected in the indication for surgery, which was not only based on visual acuity, but was further indicated as an antiglaucomatous cataract surgery in 10% of cases.

    IOL power and choice

    AL moderately correlated with the IOL power (figure 3A). IOL power was not significantly different between HH and RAM, in nanophthalmic eyes IOL power was significantly higher (figure 3B). 49 of the cases were implanted with a toric IOL, 18 of the 300 eyes received multifocal IOLs. Figure 3C–E showcases the IOL power and the distribution of different IOL manufacturers in the study population (figure 3D) and in cases with 34 D or more (figure 3E). Specific series like the HumanOptics Xtreme Series dominate at 34 D and above.

    Figure 3
    Figure 3

    IOL choice and power. (A) Axial length and IOL power show a moderate correlation. For better presentation, two eyes implanted with 56 and 58 dpt are not depicted. (B) IOL power is significantly higher in nanophthalmic eyes with an average of 34 dpt. (C) Distribution of the IOL power in the studied cohort. Only cases with an IOL power of 30D or more were investigated in the present study. The highest used IOL power was +58 dioptres. (D) and (E) J&J, Carl Zeiss Meditec and Alcon were the most frequently used manufacturers in our study population. In the extreme subset of cases with 34 D or more, HumanOptics was the most frequently used manufacturer. HH, high hyperopia; IOL, intraocular lens; N, nanophthalmos; RAM, relative anterior microphthalmos.

    Preoperative and postoperative refraction

    The mean preoperative spherical equivalent (SE) was +6±2.85 D. 288 eyes were targeted at emmetropia, with a postoperative SE of −0.42±1.56 D. 11 eyes at target refraction of −1 to −2.5 D. Only one case was aimed at +4 D to fit to the partner eye. Figure 4A, B depicts histograms of the preoperative and postoperative refraction. From all eyes with emmetropic target refraction and available postoperative refraction (127 eyes), 68.5% were within ±1 D of their target refraction, and 85.8% landed within a 2 dioptres range.

    Figure 4
    Figure 4

    Preoperative and postoperative refraction of eyes with available data and visual outcomes. (A) The studied population was highly hyperopic prior to surgery with spherical equivalents (SE) up to 17.625 D (N=269). (B) Postoperatively, the majority of patients reached an SE between −2 and +2 D. However, refractive surprises occurred. Postoperative values are only shown for patients with emmetropia as target refraction. (N=138). (C) In a subset of patients with available data for postoperative CDVA, a slight improvement in visual acuity was observed. (N=123). (D) Postoperative CDVA by the morphologies. (N=142). (E) Preoperative CDVA predicted postoperative results. (N=133). CDVA, Corrected Distance Visual Acuity; HH, high hyperopia; logMAR, Logarithm of the Minimum Angle of Resolution; MH, moderate hyperopia; N, nanophthalmos; RAM, relative anterior microphthalmos; UDVA; Uncorrected Distance Visual Acuity.

    Preoperative and postoperative visual acuity

    There was no statistically significant difference between the preoperative Corrected Distance Visual Acuity (CDVA) and postoperative Uncorrected Distance Visual Acuity (UDVA) (p=0.59, 235 eyes). Comparison of preoperative and postoperative CDVA in patients who wished to be followed-up on in our tertiary eye care postoperatively showed a slight, but statistically significant improvement in CDVA from 0.35±0.39 to 0.30±0.32 Logarithm of the Minimum Angle of Resolution (logMAR) (133 eyes, p=0.02). Postoperative UDVA was significantly greater in highly hyperopic eyes compared with nanophthalmic eyes (p=0.03). No statistically significant difference in postoperative CDVA was apparent between the three morphologies. The preoperative CDVA predicted postoperative CDVA. These results are presented in figure 4C–E.

    Intraoperative and postoperative complications

    Intraoperative and postoperative complications were rare. In 3% of cases, a posterior capsule rupture with vitreous body prolapse requiring anterior vitrectomy occurred. Only two cases showed an elevated intraocular pressure on postoperative day 1, which could be controlled with topical therapy. On average, intraocular pressure (IOP) was significantly lower on postoperative day 1 (p<0.001) with a mean pressure reduction of 2.2 mm Hg.

    OCT data

    In this study population, 16 (5.3%) of the 300 eyes showed a newly developed cystoid macular oedema postoperatively.

    Sensitivity analysis

    To account for postoperative fluctuation of visual acuity, only patients with available UDVA of 1 month or longer postoperatively were included in the analysis. The primary results remained robust, postoperative UDVA was still not significantly different from preoperative CDVA (p=0.35). After excluding eyes with known amblyopia, postoperative UDVA was still not significantly different to preoperative CDVA (p=0.25).

    Discussion

    Summary

    In this study, we characterised the patient population undergoing lens surgery with the implantation of high-power IOLs in the largest cohort available to date. Complications of hyperopia, a high prevalence of amblyopia and previous strabismus surgery, glaucoma and iridotomies and iridectomies were prevalent. We found that lens surgery, while less predictable, is safe.

    Prevalence of high-power IOLs in the study cohort

    HH has a prevalence of 1–2% of patients.1 2 However, given that our study population comprises extremely short eyes with some reaching ALs<15 mm, the prevalence of 1.2% (313 from 25 586 eyes) is extraordinarily high. This can be explained by the healthcare structure in Germany. While most uncomplicated cataract surgery cases are performed by local surgeons, complex cases, such as the ones studied here, are often referred. The tertiary eye hospital studied here is a nationwide centre for complex lens surgery and thus the higher prevalence can be explained.

    Morphology

    The first goal of this study was to characterise the morphologies receiving high-power IOLs. As to be expected, the largest cohort is highly hyperopic eyes with preoperative refractive errors of >5 D. However, 68 eyes of our cohort (22.7%) were classified as nanophthalmic eyes with an AL<20 mm. Interestingly, 58 eyes were not classified as either N, HH or RAM. With a fairly low refractive error of around 3 D compared with the other groups.

    Ocular comorbidities in short eyes

    Strabismus

    Highly hyperopic eyes tend to develop esotropia. Previous studies showed that 20% of children with hyperopia greater than +3.5 D had strabismus.18 Given the high collinearity between esotropia and amblyopia, reported to be around 55%,19 visual outcomes are guarded in eyes that underwent strabismus surgery that had already developed amblyopia to an extent. Even further, the amblyopia rate in our cohort was extremely high with a rate of around 15%. Due to most preventive interventions being introduced during the last decades, our patient population aged >60 years thus did not undergo preventive measures during childhood.

    Glaucoma

    Previous cross-sectional studies have shown that hyperopic patients are prone to develop primary angle closure glaucoma.20 Results from a population-based survey revealed that primary angle closure glaucoma is associated with shorter AL.21 However, the mean AL of the cohort studied here is drastically lower: the average AL in the angle closure glaucoma group was 21.92 mm reported in George et al, while our cohort showed an AL of 20.68 mm. Further, no information is available for extremely short eyes divided into their morphologies of N, HH and RAM. Nanophthalmic eyes and eyes with RAM showed higher rates of glaucoma than highly hyperopic eyes and also higher rates of Yttrium Aluminum Garnet (YAG)-iridotomies to relieve angle closure. Previously, few reports have focused specifically on RAM. The most precise data available is by Nihalani and colleagues22 published in 2005 reporting glaucoma rates of 34.5% in a mostly Indian population. Here, we report a prevalence of around 18.5% in RAM and an even higher prevalence in nanophthalmic eyes of over 20%. The shallow anterior segment of both entities thus has a great effect on angle closure. To further the understanding of anterior chamber morphology, we additionally conducted analysis in the anterior chamber angle. Anterior chamber depth and the anterior chamber angle are closely intertwined and crucial for the detection of eyes at risk for angle closure. Cataract surgery is known to widen the anterior chamber angle.23 24 Here, we showed a significant increase in the anterior chamber angle in all quadrants effectively preventing angle closure.

    Visual acuity

    Outcomes on visual acuity in extremely short eyes are sparse. Further, different definitions of N, RAM and HH complicate comparing results between studies. Previously, Nihalani et al investigated visual outcomes in 84 eyes with RAM, where they found that visual outcomes are often limited due to the abovementioned comorbidities. However, surgeries were performed to the standard two decades ago and may not represent the current standard. In contrast, Yosar et al reported that in three of four eyes, visual acuity improves after surgery and only one of eight eyes has worse visual acuity than preoperatively. Data of Zheng et al 25 analysing 11 eyes with simple N and an AL of <18 mm and 11 eyes with RAM, visual acuity improvement was significantly greater in the RAM group. However, they reiterate that visual outcomes are guarded, with the median CDVA in the nanophthalmic cohort reaching 20/200 and 20/60 preoperatively and postoperatively, respectively. In line, we saw a slight increase in CDVA after surgery. We saw no clinically relevant difference in the visual outcomes between the morphologies. As expected, preoperative visual acuity strongly predicted the postoperative success. Thus, based on this comprehensive data set, patients should be informed about the expected postoperative UDVA as similar to their preoperative CDVA. Given the high refractive error and preoperative spectacle dependence, most patients will still notice a major improvement in their quality of life.

    Preoperative and postoperative refraction

    Preoperative refraction was significantly different between the three entities, with nanophthalmic eyes reaching the highest average refractive error of over 7 dpt. In contrast to previous reports from 1982,12 eyes classified as RAM were highly hyperopic in this study, most likely due to the primary inclusion criteria of the present study. Thus, results especially for RAM are valid for eyes with RAM and a fairly small posterior segment. This also explains the rather low rate of RAM in our cohort compared with previous reports where the majority of RAM patients presented with a myopic refractive error.26

    IOL calculation

    IOL calculation in the extremely short eye is challenging and has undergone technological advances during the last two decades. MacLaren et al 27 concluded that of the classic well-known formulas, Haigis was most precise in these eyes. These results were confirmed by Shrivastava et al in 201928 in 85 patients with an AL of <22 mm in 2019 and further reiterated by Lin et al. 11

    While previous studies only examined well-known and established IOL formulas, in another article by Kane and Melles8 examining cases implanted with a high-power IOL, the Kane formula and the Emmetropia Verifying Optical (EVO) 2.0 slightly outperformed the Haigis formula, which again was proven to be the superior classic formula. As these modern formulas were not available for the vast majority of the study period of the present study, refractive outcomes of our study may slightly underestimate what is achievable with the current IOL calculation technology. Further studies in this largest-to-date cohort focused solely on IOL calculation should elucidate the possible advantages of modern formulas further.

    Complications

    Further, we analysed intraoperative and postoperative complications. 3% of cases experienced intraoperative posterior capsule rupture. Compared with literature values of up to 5%29 and recent data from a large retrospective study using the EUREQUO database reporting an incidence of 1.1%,30 the incidence reported results are within the previously reported range. However, given the level of experience at a tertiary eye care centre specialised in complex lens surgery, this percentage showcases the complexity of cases with extremely shallow anterior segments. Other intraoperative complications were mild. Regarding postoperative complications, we observed cystoid macular oedema in 5% of all included eyes. This is supported by a smaller cohort published by Yosar et al.9 Possibly, the extremely short AL predestines these eyes to develop an inflammatory response also in the posterior segment.

    Limitations

    An inherent limitation of this study is its retrospective design. However, due to the low number of cases per year, a prospective design is unpracticable and the current literature consists only of small retrospective cohorts still warranting a great knowledge gain from this study. Further, the German healthcare structure incentivises a quick handover from surgeons to conservative ophthalmologists, creating a larger percentage of loss to follow-up. However, patients with complications (such as cystoid macular edema (CME)) will be most likely referred to the surgeon. Further, the retrospective nature of the data may limit a more detailed analysis, in particular of the early postoperative corneal oedema, pachymetry and inflammation status.

    Conclusions

    In conclusion, this study comprises the largest cohort to date of eyes with implanted high-power IOLs. Lens surgery is safe in these eyes; however, high prevalence of comorbidities like glaucoma should be kept in mind. Based on our data, pronounced visual gains are uncommon in this population; however, uncorrected vision improves leading to great patient satisfaction.

    Data availability statement

    Data are available upon reasonable request. The datasets generated and analysed during the current study are not publicly available, but are available from the corresponding author upon reasonable request.

    Ethics statements

    Patient consent for publication

    Ethics approval

    This study involves data from human participants. The collection of patient’s data was registered in the German Clinical Trials Register (Deutsches Register Klinischer Studien) under the reference number DRKS00007837 and approved by the local Ethics Committee of the University of Heidelberg under the reference number: S-392/2011. This study adhered to the tenets of the Declaration of Helsinki. Due to the retrospective design and the large number of screened patients, informed consent was waived.

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    Footnotes

    • Presented at Part of this study was presented at the Annual Conference of the German Ophthalmology Society 2024 in Berlin, Germany.

    • Contributors Conception and design, obtained funding and overall responsibility: GUA. Guarantor: GUA. Data collection: MH, LT, MF, ER, LB, RK, TMY, GUA. Analysis, interpretation and writing: MH, LT, TMY, GUA. Manuscript revision: MH, LT, MF, ER, LB, RK, TMY, GUA.

    • Funding GUA is funded by the Klaus-Tschira-Stiftung (00.265.2015).

    • Competing interests RK reports grants, personal fees and non-financial support from Alcon, during the conduct of the study; grants, lecture fees and non-financial support from Hoya and Johnson & Johnson, grants and lecture fees from Bausch+Lomb, lecture fees and non-financial support from Carl Zeiss Meditec and Ophtec, lecture fees from Acufocus, Heidelberg Engineering, Oculus and Rayner, outside the submitted work. TMY reports lecture fees from Alcon Laboratories, Johnson & Johnson Vision and Hoya Corp. and non-financial support from Johnson & Johnson Vision. GUA reports lecture fees and research grants from Johnson & Johnson Vision, Alcon Laboratories, Carl Zeiss Meditec AG, Hoya Corp., Kowa Co., Ltd., Oculentis GmbH/Teleon, Physiol S.A., Rayner Intraocular Lenses Ltd., Oculus Optikgeräte GmbH, Ophthec BV, Santen, Sifi Medtech Srl, Acufocus Inc., Novartis, Ursapharm and Biotech; non-financial support from Rheacell, Contamac, Cristalens, Croma, EyeYon, Hanita, and VSY outside the submitted work. All other authors do not declare any conflicts of interest.

    • Provenance and peer review Not commissioned; externally peer reviewed.