Ophthalmic statistics note 1: unit of analysis

Comparison of Different Intraocular Lens Power Calculation Formulas in Eyes With Primary Angle Closure

STUDY DESIGN

Prospective case series.

PRCIS

This prospective study determines which formulas can best predict the refractive outcome in patients with primary angle closure disease (PACD) after cataract surgery.

OBJECTIVE

To compare the accuracy of 6 intraocular lens power calculation formulas, Barrett Universal II (BU II), Haigis, Hoffer Q, Holladay I, Kane and SRK/T, in eyes with PACD.

PATIENTS AND METHODS

Patients diagnosed with PACD and cataracts and who met the indication for cataract surgery were enrolled in the study. Six intraocular lens power calculation formulas were used to calculate the refractive diopter. The percentage of eyes with prediction error (PE) within ±0.50 D and the median absolute PE were compared to determine the accuracy of different formulas in patients with PACD. Subgroup analysis was performed according to axial length (AL). The accuracy of BU II was compared between patients with PACD and patients with age-related cataracts.

RESULTS

One hundred five patients (105 eyes) with PACD and 35 patients (35 eyes) with age-related cataracts were enrolled in the study. Haigis, Kane, and BU II formula achieved a comparable outcome and outperformed over the other 3 formulas in patients with PACD. Subgroup analysis showed that the group with long AL has lower values of median absolute PE. PE was significantly positively correlated with AL and negatively correlated with relative lens position when calculated using BU II and Kane.

CONCLUSIONS

Haigis, Kane, and BU II formula achieved a comparable outcome and outperformed over the other 3 formulas in patients with PACD.

Evaluation of the presence of double-organ bias in published randomised controlled dacryocystorhinostomy studies

OBJECTIVE

The aim of this study is to show whether journals pay attention to double-organ bias in studies on dacryocystorhinostomy (DCR) treatment. Most statistical tests are based on the assumption that each data entry is independent of the other. However, we wanted to understand whether the eye, which is a double organ in the human body, is a cause of bias and whether sufficient attention has been paid to it in published articles.

DESIGN

A PubMed search was conducted between November 1997 and November 2021 in the field of ophthalmology and otolaryngology with the terms 'dacryocystorhinostomy' and the limitations of 'people' and 'randomly controlled studies'. Publications containing DCR were searched. The publications published in the 15 journals with the highest impact were selected. The scope of the journal, the scope of the authors, the relevance of the articles, the presence of randomisation, the type of study (drug, endoscopic surgery, laser surgery and external surgery) and the statistical approach to bilateral organ bias were evaluated by two independent observers.

RESULTS AND MAIN OUTCOME MEASURES

A total of 83 publications were found by Pubmed search. Fifty-six publications were included in the study. Double-organ bias was present in 41% (n = 23) of the cases. Of the 23 biased publications, 46.4% were found to be in the Quartile 1 group. Quartile 4 journals showed bias in only four journals.

CONCLUSION

Double-organ bias can also be seen in journals with high impact factors and published in recent years. Journals may need to pay more attention to double-organ bias in the publication acceptance process.

Incidence and characteristics of aqueous misdirection after glaucoma surgery in Chinese patients with primary angle-closure glaucoma

BACKGROUND

To report the incidence and clinical characteristics of aqueous misdirection (AM) after glaucoma surgery in Chinese patients with primary angle-closure glaucoma.

METHODS

Medical records of all patients diagnosed with primary angle-closure glaucoma who underwent glaucoma surgery in the Eye Hospital of Wenzhou Medical University between January 2012 and December 2021 were retrospectively reviewed. Cases of AM were identified through a keyword-based search. The incidence of AM was calculated. Demographic and clinical characteristics of the AM patients were also described.

RESULTS

A total of 5044 eyes with primary angle-closure glaucoma were included (mean age 65.81 ± 9.96 years, 68.11% women). Thirty-eight eyes developed AM, presenting an overall incidence of 0.75%. The mean time interval between surgery and first record of AM diagnosis was 2.57 ± 5.24 months (range, 0 day to 24 months). The incidence of AM was significantly higher in patients aged ≤ 40 years (21.28%) and those aged 40-50 years (3.32%), compared to those > 50 years (0.42%) (P < 0.001). AM developed much more frequently among patients with chronic angle-closure glaucoma (1.30%), compared to those with acute angle-closure glaucoma (0.32%, P < 0.001). Eleven eyes (0.37%) developed AM following non-filtering surgery compared to 24 eyes (2.27%) after filtering surgery (P < 0.001).

CONCLUSION

The incidence of AM after glaucoma surgery was 0.75% in Chinese patients with primary angle closure glaucoma. Younger age, chronic angle-closure glaucoma, and undergoing filtering surgery, were identified as associated risk factors for developing AM. Phacoemulsification may have less risk of developing AM compared to filtering surgery.

Visual outcomes and predictors in optic pathway glioma: a single centre study

BACKGROUND/AIMS

Optic pathway gliomas (OPGs) may cause progressive visual loss despite chemotherapy. Newer, less toxic treatments might be given earlier, depending on visual prognosis. We aimed to investigate the prognostic value of visual evoked potentials (VEP) and optical coherence tomography (OCT).

METHODS

A retrospective study of OPG patients (treated 2003-2017) was conducted. Primary outcome was PEDIG category visual acuity in better and worse eyes (good < = 0.2, moderate 0.3-0.6 and poor > = 0.7 logMAR). Binary logistic regression analysis was used to identify predictors of these outcomes.

RESULTS

60 patients (32 Neurofibromatosis type 1 [NF1] and 28 sporadic) had median presentation age 49 months (range 17-183) (NF1) and 27 months (range 4-92) (sporadic). Median follow up was 82 months (range 12-189 months). At follow up 24/32 (75%) of NF1 children and 14/28 (50%) of sporadic children had good better eye visual acuity and 11/32 (34%) of NF1 children and 15/28 (54%) of sporadics had poor worse eye acuity. Mean peripapillary retinal nerve fibre layer (RNFL) thickness predicted good better eye final acuity (OR 0.799, 95%CI 0.646-0.987, p = 0.038). Presenting with visual symptoms (OR 0.22 95% CI 0.001-0.508, p = 0.017) and poorer VEP scores (OR 2.35 95% CI 1.1-5.03, p = 0.027) predicted poor worse eye final acuity. 16 children had homonymous hemianopias at follow up, predicted by poor presenting binocular VEP score (OR 1.449 95%CI 1.052-1.995, p = 0.02).

CONCLUSIONS

We found that both RNFL thickness on OCT and VEP were useful in predicting future visual acuity and vision and potentially in planning treatment. We had a high prevalence of homonymous hemianopia.

Retrospective review of the effectiveness of orthokeratology versus soft peripheral defocus contact lenses for myopia management in an academic setting

PURPOSE

To evaluate the relative efficacy of peripheral defocus contact lenses (PDCLs) and orthokeratology (OK) in a real-world clinical population, and compare these results with previous randomised controlled clinical trials.

METHODS

Records from a university practice were reviewed to identify children who were treated with OK or PDCLs. The analysed sample contained 273 visits from 77 patients. Annualised rates of axial length (AL) progression were calculated and used as the response variable in both linear mixed-effects (LME) and nonlinear regression models.

RESULTS

On average, children were 10.7 years of age at baseline (p = 0.14 between treatments), and most patients were female. More Asian children wore OK lenses compared with PDCLs (p < 0.01). At baseline, children had ~3.00 D of myopia and 0.75 D of astigmatism in both treatment groups (p > 0.20 between treatments). LME regression models using only baseline covariates showed no evidence that the annualised change in AL differed between treatments, with or without the inclusion of age, race, sex, baseline AL or spherical equivalent refractive error. Across all possible subsets of models, age at baseline was the best predictor of annualised AL change. There was no statistical difference between parameters of an exponential decay model fitted within treatment using follow-up age as a time-varying predictor, indicating that the rate of annualised change in AL was similar for OK and PDCL.

CONCLUSIONS

Retrospective analysis of real-world clinical data found no difference in annualised AL growth between PDCL and OK. Importantly, the AL progression from this clinical setting is consistent with that reported in randomised clinical trials. Therefore, continued research of real-world performance is warranted to understand the safety and efficacy of modern myopia control treatments in the broader population.

The bactericidal effect of two photoactivated chromophore for keratitis-corneal crosslinking protocols (standard vs. accelerated) on bacterial isolates associated with infectious keratitis in companion animals

Background

Bacterial corneal infections are common and potentially blinding diseases in all species. As antibiotic resistance is a growing concern, alternative treatment methods are an important focus of research. Photoactivated chromophore for keratitis-corneal crosslinking (PACK-CXL) is a promising oxygen radical-mediated alternative to antibiotic treatment. The main goal of this study was to assess the anti-bactericidal efficacy on clinical bacterial isolates of the current standard and an accelerated PACK-CXL treatment protocol delivering the same energy dose (5.4 J/cm²).

Methods

Clinical bacterial isolates from 11 dogs, five horses, one cat and one guinea pig were cultured, brought into suspension with 0.1% riboflavin and subsequently irradiated. Irradiation was performed with a 365 nm UVA light source for 30 min at 3mW/cm² (standard protocol) or for 5 min at 18mW/cm² (accelerated protocol), respectively. After treatment, the samples were cultured and colony forming units (CFU’s) were counted and the weighted average mean of CFU’s per μl was calculated. Results were statistically compared between treated and control samples using a linear mixed effects model.

Results

Both PACK-CXL protocols demonstrated a significant bactericidal effect on all tested isolates when compared to untreated controls. No efficacy difference between the two PACK-CXL protocols was observed.

Conclusion

The accelerated PACK-CXL protocol can be recommended for empirical use in the treatment of bacterial corneal infections in veterinary patients while awaiting culture results. This will facilitate immediate treatment, the delivery of higher fluence PACK-CXL treatment within a reasonable time, and minimize the required anesthetic time or even obviate the need for general anesthesia.

Statistical Evaluation of Correlated Measurement Data in Longitudinal Setting Based on Bilateral Corneal Cross-Linking

PURPOSE

In ophthalmology, data from both eyes of a person are frequently included in the statistical evaluation. This violates the requirement of data independence for classical statistical tests (e.g. t-Test or analysis of variance (ANOVA)) because it is correlated data. Linear mixed models (LMM) were used as a possibility to include the data of both eyes in the statistical evaluation.

METHODS

The LMM is available for a variety of statistical software such as SPSS or R. The application was applied to a retrospective longitudinal analysis of an accelerated corneal cross-linking (ACXL (9*10)) treatment in progressive keratoconus (KC) with a follow-up period of 36 months. Forty eyes of 20 patients were included, whereas sequential bilateral CXL treatment was performed within 12 months. LMM and ANOVA for repeated measurements were used for statistical evaluation of topographical and tomographical data measured by Pentacam (Oculus, Wetzlar, Germany).

RESULTS

Both eyes were classified into a worse and better eye concerning corneal topography. Visual acuity, keratometric values and minimal corneal thickness were statistically significant between them at baseline (p < 0.05). A significant correlation between worse and better eye was shown (p < 0.05). Therefore, analyzing the data at each follow-up visit using ANOVA partially led to an overestimation of the statistical effect that could be avoided by using LMM. After 36 months, ACXL has significantly improved BCVA and flattened the cornea.

CONCLUSION

The evaluation of data of both eyes without considering their correlation using classical statistical tests leads to an overestimation of the statistical effect, which can be avoided by using the LMM.

Standard automated perimetry using size III and size V stimuli in advanced stage glaucoma: an observational cross-sectional comparative study

OBJECTIVES

In this study, we sought to evaluate the extent of further visual field that could be assessed when using stimulus size V in standard automated perimetry compared with size III in advanced stage glaucoma and whether cut-off values could be determined for when to switch from size III to size V.

DESIGN

Prospective cross-sectional study.

SETTING

Single-centre outpatient eye clinic in India (New Delhi).

PARTICIPANTS

Advanced stage glaucoma defined as stages 3-4.

INTERVENTION

Central static perimetry with Octopus 900 G programme (size III stimulus dynamic strategy) and low vision central programme (size V stimulus dynamic strategy).

PRIMARY AND SECONDARY OUTCOME MEASURES

Visual field assessment for right and left eyes with both sizes III and V were undertaken within one clinic visit.

RESULTS

We recruited 126 patients (170 eyes). Mean patient age at assessment was 55.86 years (SD 15.15). Means (SD) for size III versus size V, respectively, were 6.94 dB (5.58) and 12.98 dB (7.77) for mean sensitivity, 20.02 dB (5.67) and 19.22 dB (7.74) for mean deviation, 5.89 dB (2.29) and 7.69 dB (2.78) for standard loss variance and 3.32 min (1.07) and 6.40 min (1.43) for test duration. All except mean deviation were significantly different between size III and V tests.

CONCLUSION

Useful visual field information was obtained with size V stimuli which allowed continued monitoring of these patients that was not possible with size III. Increased test duration, standard loss variance and mean sensitivity were found with size V, as expected, given that more visual responses were obtained with the increased target size. A switch from size III to V may be considered when mean sensitivity reaches 10 dB and/or mean deviation reaches 18 dB.

Tomographic and aberrometric assessment of first-time diagnosed paediatric keratoconus based on age ranges: a multicentre study

PURPOSE

To describe paediatric keratoconus (KC) patients by tomographic and aberrometric characteristics at first diagnosis, in a multicentre study.

METHODS

We included 278 eyes from 139 paediatric patients, with a first tomographic diagnosis (Pentacam^® ) of KC prior to 18 years old. KC classification was based on the KC Index (≥ 1.07) and Topographic Keratoconus Classification (TKC ≥ 1). Patients were divided based on age ranges (14 and under and over 14 years) and gender. Statistical analysis was performed with SPSS statistics 25.0. ANOVA factor was carried out comparing to compare groups.

RESULTS

278 eyes were screened, and 230 eyes were diagnosed with paediatric KC. Mean age was 15.48 ± 2.33 (6 to 18) years. We found differences in terms of TKC (2.08 ± 0.89 and 2.38 ± 0.82, p < 0.05) and spherical aberration (-0.71 ± 0.97 and -1.07 ± 1.36, p < 0.05) among the 14 years old or under and above 14 years old groups, respectively. Overall, female paediatric KC patients presented a more severe TKC, Belin Ambrosio Display, maximum keratometry, asphericity and primary and secondary coma aberrations compared to male KC patients. We observed a correlation between CDVA and asphericity (r = 0.71, p < 0.01), as well as between CDVA and spherical aberration (r = 0.69, p < 0.01).

CONCLUSION

Our findings revealed that the debut of KC is usually in a moderate to advanced stage in the paediatric population at first diagnosis, particularly in female patients. Corneal tomography should be systematically performed in children with recent onset of corneal astigmatism.

Double-Organ Bias in Controlled Trials on Eyelid Ptosis

PURPOSE

Proper statistical analysis is an essential element in the evaluation of clinical trial outcomes. We had the informal observation that double-organ bias was a neglected issue during the statistical analyses of clinical trials on eyelid ptosis. The aim of this study was to formally document the prevalence of this bias in these studies.

METHODS

Clinical trials on eyelid ptosis, published in the last 20 years, were searched in PubMed with the terms; "((blepharoptosis) OR upper eyelid ptosis) OR eyelid ptosis" and with the filters "Randomized Controlled Trial (RCT), Clinical Trial, Humans." Two independent observers evaluated the articles for eligibility, field of the journal, field of the authors, presence of randomization, type of the study (surgical, medical), and statistical approach to double organ bias.

RESULTS

The PubMed search yielded 101 articles and 23 of them met the above-mentioned criteria. In 3 articles, primary outcome measure was not related with the eyes. Among the remaining 20 articles, 14 (70%) had double-organ bias in the statistics. The bias was slightly less common in randomized trials (60% vs. 80%), but the difference was not statistically significant. Its prevalence was similar between ophthalmology journals and the rest (p = 0.64). Interestingly, the bias tended to be more in Q1 journals (87.5%) compared to Q2 and Q3 journals (58.3%) and median impact factor was higher in biased articles (1.82 vs. 1.29), but the differences weren't statistically significant (p = 0.32, p = 0.24). There was no difference between the last 2 decades (66.6% vs. 75%, p = 0.64).

CONCLUSIONS

The prevalence of the double-organ bias was very high in published clinical trials on eyelid ptosis (70%) and even among RCTs (60%). The prevalence of the bias didn't prevent publication in higher impact factor journals and didn't change between journals from different disciplines or over time.

Clinical Characteristics of Patients With Chronic Stevens-Johnson Syndrome Treated at a Major Tertiary Eye Hospital Within the United Kingdom

The purpose of this study is to provide a comprehensive review of the clinical characteristics in chronic Stevens-Johnson syndrome (SJS) patients within the United Kingdom population, their causative factors, treatment profile and prognosis. This retrospective series included 91 patients with chronic SJS treated at Moorfields Eye Hospital (London, United Kingdom). A chart review included visual acuity and presence of clinical findings (including lid abnormalities and ocular surface findings). All medical and surgical treatments were also recorded. Approximately a half of patients were White British but there were significant numbers of patients from other ethnic groups, South Asian and Black in particular. Oral antibiotics were the causative agent in almost a half of the patients with SJS, systemic infections in 14%, non-steroidal anti-inflammatory drugs in 8% and anticonvulsants in 7%. The age of onset was varied but a significant proportion of patients developed acute SJS in childhood. There was a significant correlation between visual acuity at initial referral to final recorded vision. Vision was found to continue to significantly deteriorate over time despite therapeutic interventions. Our regression model shows that ~62% of the variance in final vision can be explained by the initial vision and duration disease. The majority of our patients were on advanced ocular surface treatments including serum drops, topical ciclosporin and retinoic acid drops. Of particular significance, approximately a third of our patient cohort was also on systemic immune suppression. In conclusion, chronic SJS within the UK population under tertiary care remains an area of unmet clinical need. Current medical and surgical modalities prevent worsening of vision in severe ocular disease from SJS.

Challenges in using both eyes of the same patient when evaluating the results after implantation of intrastromal corneal ring segments

PURPOSE

To assess correlation between results from both eyes of the same patient after implantation of intrastromal corneal ring segments (ICRS) and define whether they can be used together in clinical studies.

METHODS

A review of medical records of 74 patients with keratoconus implanted with bilateral Ferrara ICRS at Centro de Oftalmología Barraquer from January 2005 until December 2014. Data were collected on uncorrected visual acuity, best-corrected visual acuity and subjective refractive values (sphere, cylinder and axis).

RESULTS

A total of 39 patients were male (53%), and 35 were female (47%). Mean age at the time of implantation was 32.5 ± 10 years. No major complications occurred. A significant correlation between the results from right and left eyes was found (p < 0.0043), indicating that both eyes significantly resembled each other. No significant interaction in the magnitude of change between eye and surgery was observed under classic and mixed models.

CONCLUSION

Based on our data, whenever application is not possible under mixed-model analyses, we recommend the use of a first eye operated only, either right or left, in order to avoid bias and errors derived from autocorrelation and guarantee the independence of the registered observations.

Comparison of Phakic Intraocular Lens Vault Using Conventional Nomogram and Prediction Formulas

This study aimed to compare the achieved vault using a manufacturer's nomogram and the predicted vault using the currently available prediction formulas after posterior chamber phakic intraocular lens (EVO Implantable Collamer Lens; ICL, STAAR Surgical) implantation. We included 200 eyes of 100 consecutive patients (mean age ± standard deviation, 34.3 ± 7.8 years) undergoing ICL implantation with a central hole. Three months postoperatively, we quantitatively measured the actual vault, and we compared it with the predicted vault using anterior segment optical coherence tomography (CASIA 2, Tomey). The agreement rate of the recommended ICL size using the manufacturer's nomogram, the NK formula, and the KS formula was 50.0%. The achieved vault was 477.1 ± 263.7 µm, which was significantly smaller than the predicted vaults of 551.2 ± 335.1 and 606.4 ± 212.2 µm, using the NK and KS formulas, respectively (Dunnett test, p = 0.014, p < 0.001). The achieved vault was not significantly different from the predicted vault using the NK or KS formula (p = 0.386, p = 0.157) when selecting a 12.1 mm ICL size. It was not significantly different from the predicted vault using the NK formula (p = 0.962), but it was significantly smaller than that using the KS formula (p = 0.033) when selecting a 12.6 mm size. It was significantly smaller than the predicted vault using the NK and KS formulas (p < 0.001) when selecting 13.2 mm size. The total agreement rate of the recommended ICL size was approximately 50%. The predicted ICL vault tended to overestimate the actual ICL vault, especially when selecting a larger ICL size.

Comparison of the accuracy of 11 intraocular lens power calculation formulas

Purpose

To compare the accuracy of 11 intraocular lens (IOL) power calculation formulas (SRK-T, Hoffer Q, Holladay I, Haigis, Holladay II, Olsen, Barrett Universal II, Hill-RBF, Ladas Super formula, EVO and Kane).

Setting

Private university hospital (QuironSalud, Madrid, Spain).

Design

Retrospective case series

Methods

Data were compiled from 481 eyes of 481 patients who had undergone uneventful cataract surgery with IOL insertion. Preoperative biometric measurements were made using an IOL Master® 700. Respective ULIB IOL constants ( http://ocusoft.de/ulib/c1.htm ) for each of 4 IOL models implanted were used to calculate the predictive refractive outcome for each formula. This was compared with the actual refractive outcome determined 3 months postoperatively. The primary outcome was mean absolute prediction error (MAE). The study sample was divided according to axial length (AL) into three groups of eyes: short (⩽22.00 mm), normal (22.00–25.00 mm) and long (⩾25.00 mm).

Results

The Barrett Universal II and Haigis formulas yielded the lowest MAEs over the entire AL range ( p < .01, except EVO) as well as in the long ( p < .01, all formulas) and normal ( p < .01, except Haigis, Holladay II, Olsen and LSF) eyes. In the short eyes, the lower MAEs were provided by Haigis and EVO ( p < .01 except Hoffer Q, SRK/T and Holladay I).

Conclusions

Barrett Universal II was the most accurate for IOL power calculation in the normal and long eyes. For short eyes, the formulas Haigis and EVO seem best at predicting refractive outcomes.

RE-PERG in early-onset Alzheimer's disease: A double-blind, electrophysiological pilot study

PURPOSE

To evaluate the ability of re-test pattern electroretinogram (RE-PERG), a non-invasive and fast steady-state PERG, to detect inner retinal bioelectric function anomalies in patients with early-onset Alzheimer's disease (AD).

METHODS

The study population consisted of 17 patients with AD-related mild cognitive impairment (MCI), 16 patients with vascular dementia (VD)-related MCI, both assessed using the neuropsychological Mini-Mental State Examination (MMSE) and by structural magnetic resonance imaging, and 19 healthy, age-matched normal controls (NC). All participants were visually asymptomatic, had normal or near-normal general cognitive functioning and no or minimal impairments in daily life activities. Visual field (VF) test, optical coherence tomography (OCT) and RE-PERG, sampled in five consecutive blocks of 130 events, were performed.

RESULTS

There was no statistically significant difference among the three groups with respect to age, VF parameters (mean and pattern standard deviations) and OCT parameters (ganglion cell complex thickness and retinal nerve fiber layer thickness). The mean amplitude in the RE-PERG was significantly lower, but only weakly in the AD group than in NC (p = 0.1) whereas the intrinsic variability of the 2nd harmonic phase was significantly higher in the AD group than in either the VD or NC group (p<0.001).

CONCLUSIONS

RE-PERG is altered in early-stage AD, showing a reduced amplitude with high intrinsic phase variability. It also allows the discrimination of AD from VD. A high intrinsic variability in the PERG signal, determined using RE-PERG, may thus be a new promising test for neurodegenerative diseases.

Octopus 900 Automated Kinetic Perimetry versus Standard Automated Static Perimetry in Glaucoma Practice

Purpose: The presence of central visual field loss does not infer the extent of peripheral visual field loss. In advanced stage glaucoma, we evaluated whether automated kinetic perimetry provided additional visual field information to that of central static perimetry. Materials and Methods: We undertook a prospective cross-sectional study of advanced-stage glaucoma defined as stages 3-4. Visual field assessment for right and left eyes was undertaken within one clinic visit using the Octopus 900 G programme and kinetic strategy. Results: We recruited 126 patients (170 eyes). Mean patient age at assessment was 55.86 years (SD 15.15). Mean kinetic reaction time was 1503.96 ms (SD 801.68). Kinetic I4e was plotted in 71% of eyes with an unadjusted area of 2513.68 degrees² (SD 2397.91) and mean isopter radius of 23.16 degrees (SD 13.07). Kinetic I2e was plotted in 53.5% of eyes with an unadjusted area of 627.07 degrees² (SD 1291.94) and mean isopter radius of 7.47 degrees (SD 10.59). Increased reaction time was associated with a poorer visual field (p = .001). Mean sensitivity, mean deviation and standard loss variance values on static perimetry were higher in patients who had a defined kinetic field boundary than in patients with no kinetic response to I4e stimulus (p = .0001). However, this corresponded to only small-to-medium correlation between static fields and existent kinetic fields: the presence of poor static fields did not always infer a poor kinetic visual field as poor static fields could also have good kinetic visual fields. Conclusions: Although we confirmed a lack of agreement and only a small to medium correlation between the extents of central versus peripheral visual field loss, automated kinetic perimetry did provide additional peripheral (outside the static 30-degree central field) visual field information which was clinically useful in the presence of non-informative severely defected central visual fields.

Association of CD11b+ Monocytes and Anti-Vascular Endothelial Growth Factor Injections in Treatment of Neovascular Age-Related Macular Degeneration and Polypoidal Choroidal Vasculopathy

Importance

CD11b+ immune cells have been implicated in the formation of choroidal neovascularization in experimental studies on animals and disease-association studies on humans. However, the clinical importance of such observations remains unknown.

Objective

To investigate whether the proportion of CD11b+ circulating monocytes is associated with the number of anti-vascular endothelial growth factor (anti-VEGF) injections in neovascular age-related macular degeneration (AMD) and polypoidal choroidal vasculopathy (PCV).

Design, Setting, and Participants

These observational cohort studies collected data from January 1, 2010, through December 31, 2013, and from January 1, 2015, through December 31, 2018. Fresh venous blood samples were acquired for flow cytometric immune studies in patients with neovascular AMD or PCV receiving treatment with aflibercept or ranibizumab as needed for 36 months. Patients (n = 81) without immune diseases were consecutively recruited from a single center in Denmark.

Exposures

Proportion of CD11b+ circulating monocytes.

Main Outcomes and Measures

The estimation of the number of intravitreal anti-VEGF injections given at 12, 24, and 36 months by the proportion of CD11b+ circulating monocytes and the correlation between these values. The angiogenic role of CD11b+ circulating monocytes was further evaluated by investigating the expression of the known proangiogenic receptor CCR2.

Results

Eighty-one patients were included in the analysis (54% women; mean [SD] age, 76 [7] years). The proportion of CD11b+ monocytes at baseline positively estimated the future number of anti-VEGF injections at 12 (ρ = 0.77; 95% CI, 0.35-0.93; P = .004), 24 (ρ = 0.82; 95% CI, 0.44-0.95; P = .002), and 36 (ρ = 0.78; 95% CI, 0.34-0.94; P = .005) months. This association was also found retrospectively in a larger sample of patients with neovascular AMD at 12 (ρ = 0.46; 95% CI, 0.16-0.68; P = .004), 24 (ρ = 0.49; 95% CI, 0.20-0.70; P = .002), and 36 (ρ = 0.65; 95% CI, 0.41-0.80; P < .001) months and patients with PCV at 12 (ρ = 0.27; 95% CI, -0.28 to 0.68; P = .30), 24 (ρ = 0.60; 95% CI, 0.12-0.85; P = .02), and 36 (ρ = 0.70; 95% CI, 0.27-0.90; P = .005) months, suggesting that this association is not specific to AMD but rather reflects VEGF activity in neovascularization. CD11b+ monocytes highly coexpressed CCR2, an important monocytic marker of proangiogenic activity.

Conclusions and Relevance

Results of this study demonstrated that the proportion of circulating CD11b+ monocytes estimated and correlated with the number of anti-VEGF injections in patients with neovascular AMD and PCV. Additional longitudinal studies are needed to determine whether these findings have clinical relevance to influence treatment algorithms or provide novel targets for medical therapy.

Systemic Levels of Interleukin-6 Correlate With Progression Rate of Geographic Atrophy Secondary to Age-Related Macular Degeneration

Purpose

Geographic atrophy (GA) is a clinical phenotype of late age-related macular degeneration (AMD) with no current treatment available. In this study, we investigated markers of chronic inflammation in plasma of patients with GA and how these relate to progression rate.

Methods

We prospectively included 42 patients with GA, 41 patients with neovascular AMD, and 27 healthy controls. We quantified levels of interleukin (IL)-1β, IL-6, IL-8, tumor necrosis factor (TNF) receptor 2, and C-reactive protein (CRP). We adapted an inflammation summary score to cluster conceptually related markers of chronic inflammation. Enlargement rate of the atrophic lesion was measured from fundus autofluorescence images performed at baseline and after 1 year.

Results

Patients with GA showed an increase in proinflammatory markers of IL-6 (P = 0.009), TNF receptor 2 (P = 0.013), and CRP (P = 0.017) compared to healthy controls. We found that IL-8 levels were markedly higher in patients with GA when compared to patients with neovascular AMD (P = 0.013). The inflammation summary score was high in patients with neovascular AMD (P = 0.024), but even higher in patients with GA (<0.001), when compared to healthy controls. GA enlargement was measured in 36 patients, who completed follow-up. Plasma levels of IL-6 had a moderate but significant correlation with GA enlargement rate (R2 = 0.23, P = 0.0035).

Conclusions

Markers of chronic inflammation strongly associates with presence of GA secondary to AMD. Plasma IL-6 possesses predictive ability of progression and constitutes the first known plasma biomarker of disease activity in GA. These findings shed light into a poorly understood clinical phenotype of AMD and highlights the important role of chronic inflammation in GA.

Outcomes of intraocular lens scleral fixation with the friction knot technique

PURPOSE

To examine the clinical outcomes of intraocular lens (IOL) scleral fixation with the friction knot technique.

METHODS

Retrospective case series of 152 eyes of 152 patients with inadequate capsular bag support operated with the friction knot IOL scleral fixation technique by a single surgeon. The fixated IOLs were one-piece or three-piece models all with open loop haptics. Main outcome measures were change in corrected distance visual acuity (CDVA) and postoperative complications.

RESULTS

The mean follow-up time was 11.7 months (median 4.9, range 0.7-64.8). The mean logarithm of the minimum angle of resolution CDVA improved from preoperative 0.77 ± 0.73 (Snellen 20/118 ± 7.3 lines) to 0.44 ± 0.56 (Snellen 20/55 ± 5.6 lines) at the final visit (p < 0.001). The main postoperative complications were ocular hypertension (30.3%), uveitis-glaucoma-hyphaema syndrome (12.5%; UGHS), vitreous haemorrhage (11.2%) and retinal detachment (8.6%). Two (1.3%) cases of suture breakage were seen. In multivariate Cox regression analysis, age under 60 years [hazard ratio (HR) = 5.41; 95% confidence interval (CI) 1.95-15.01] and scleral fixated one-piece IOL (HR = 4.23; 95% CI 1.44-12.44) were found as significant independent risk factors for developing new UGHS.

CONCLUSION

The friction knot technique provides a firm scleral fixation. Scleral fixation may successfully be utilized in dislocated three-piece IOLs with loop haptics. We recommend avoiding scleral fixation of one-piece IOLs in young patients due to a high risk of UGHS.

Efficacy and safety of interventions to control myopia progression in children: an overview of systematic reviews and meta-analyses

Background

Myopia is a common visual disorder with increasing prevalence. Halting progression of myopia is critical, as high myopia can be complicated by a number of vision-compromising conditions.

Methods

Literature search was conducted in the following databases: Medical Literature Analysis and Retrieval System Online (MEDLINE), Excerpta Medica dataBASE (EMBASE), Cochrane Database of Systematic Reviews (CDSR), Database of Abstracts of Reviews of Effects (DARE) and Centre for Reviews and Dissemination (CRD) Health Technology Assessment (HTA) database. Systematic reviews and meta-analyses investigating the efficacy and safety of multiple myopia interventions vs control conditions, were considered. Methodological quality and quality of evidence of eligible studies were assessed using the ROBIS tool and GRADE rating. The degree of overlapping of index publications in the eligible reviews was calculated with the corrected covered area (CCA).

Results

Forty-four unique primary studies contained in 18 eligible reviews and involving 6400 children were included in the analysis. CCA was estimated as 6.2% and thus considered moderate. Results demonstrated the superior efficacy of atropine eyedrops; 1% atropine vs placebo (change in refraction: -0.78D, [− 1.30 to − 0.25] in 1 year), 0.025 to 0.05% atropine vs control (change in refraction: -0.51D, [− 0.60 to − 0.41] in 1 year), 0.01% atropine vs control (change in refraction: -0.50D, [− 0.76 to − 0.24] in 1 year). Atropine was followed by orthokeratology (axial elongation: − 0.19 mm, [− 0.21 to − 0.16] in 1 year) and novel multifocal soft contact lenses (change in refraction: -0.15D, [− 0.27 to − 0.03] in 1 year). As regards adverse events, 1% atropine induced blurred near vision (odds ratio [OR] 9.47, [1.17 to 76.78]) and hypersensitivity reactions (OR 8.91, [1.04 to 76.03]).

Conclusions

Existing evidence has failed to convince doctors to uniformly embrace treatments for myopic progression control, possibly due to existence of some heterogeneity, reporting of side effects and lack of long-term follow-up. Research geared towards efficient interventions is still necessary.

Electronic supplementary material

The online version of this article (10.1186/s12886-019-1112-3) contains supplementary material, which is available to authorized users.

Second-order visual sensitivity in the aging population

Most visual and cognitive functions are affected by aging over the lifespan. In this study, our aim was to investigate the loss in sensitivity to different classes of second-order stimuli-a class of stimuli supposed to be mainly processed in extrastriate cortex-in the aging population. These stimuli will then allow one to identify specific cortical deficit independently of visibility losses in upstream parts of the visual pathway. For this purpose, we measured the sensitivity to first-order stimuli and second-order stimuli: orientation-modulated, motion-modulated or contrast-modulated as a function of spatial frequency in 50 aged participants. Overall, we observed a sensitivity loss for all classes of stimuli, but this loss differentially affects the three classes of second-order stimuli tested. It involves all modulation spatial frequencies in the case of motion modulation, but just high modulation spatial frequencies in the case of contrast- and orientation modulations. These observations imply that aging selectively affects the sensitivity to second-order stimuli depending on their type. Since there is evidence that these different second-order stimuli are processed in different regions of extrastriate cortex, this result may suggest that some visual cortical areas are more susceptible to aging effects than others.

Unit of analysis issues in laboratory-based research

Many studies in the biomedical research literature report analyses that fail to recognise important data dependencies from multilevel or complex experimental designs. Statistical inferences resulting from such analyses are unlikely to be valid and are often potentially highly misleading. Failure to recognise this as a problem is often referred to in the statistical literature as a unit of analysis (UoA) issue. Here, by analysing two example datasets in a simulation study, we demonstrate the impact of UoA issues on study efficiency and estimation bias, and highlight where errors in analysis can occur. We also provide code (written in R) as a resource to help researchers undertake their own statistical analyses.

Effect of aging and lifestyle on photoreceptors and retinal pigment epithelium: cross-sectional study in a healthy Danish population

Photoreceptors and their supporting retinal pigment epithelium constitute the key functional parts of the retina. Here, a study was undertaken to show how aging and lifestyle factors affect the photoreceptor layer and the retinal pigment epithelium and Bruch's membrane complex (RPE-BM) in vivo in a healthy Danish population using spectral-domain optical coherence tomography. This was a cross-sectional study of healthy humans aged ≥50 years. All participants were interviewed for medical history and lifestyle factors. Maculae of all participants were scanned using spectral-domain optical coherence tomography. The thickness of the photoreceptor layer and the RPE-BM was measured on one eye from each participant. In 150 eyes of 150 participants, it was found that aging was associated with a decrease in the thickness of the photoreceptor layer (-0.143 μm/year, P = 0.031) and an increase in the thickness of the RPE-BM layer (0.100 μm/year, P = 0.029) at the foveal minimum. Regarding lifestyle factors, alcohol intake or BMI were not associated with any significant trend, but physical inactivity and smoking had effects on the photoreceptor layer (decreased thickness) and the RPE-BM layer (increased thickness) indicating an accelerated aging process of the macula. Taken together, aging affects photoreceptors and the RPE-BM, and these aging trends are accelerated in smokers and the physically inactive.

Double-Organ Bias in Published Randomized Controlled Trials of Glaucoma

PURPOSE

Most of the statistical tests used in significance testing are based on the assumption that each data entry is independent from other entries, however, we observe that in many articles researchers include data from 2 eyes as independent variables while performing these statistical tests. The aim of this study was to formally survey the prevalence of the above-mentioned "double-organ bias" in randomized controlled trials (RCT) of glaucoma.

MATERIALS AND METHODS

We did a PubMed search with the terms "glaucoma" and limitations "Humans" and "Randomized Controlled Trials" in 15 highest-impact-factor ophthalmology journals between November 2002 and November 2012. We only included RCTs published as an original article, where the aim was treating glaucoma. Two independent observers (M.K. and A.S.E.) read through each article and classified the articles according to treatment modality (medical, laser, or surgical) and presence of double-organ bias.

RESULTS

The PubMed search yielded 270 articles. A total of 130 articles qualified for the survey. Eighty-five of the RCTs were medical studies, 11 were laser studies, and 34 studies evaluated the outcome of a surgical procedure. In 17 of the 130 articles (13.1%), double-organ bias was found. Prevalence of the double-organ bias was not significantly different between medical (12.9%), laser (14.7%), and surgical (9.1%) studies.

CONCLUSION

Double-organ bias was observed around 13.1% of the published RCTs, leading to inaccurate statistical testing.

Lateral thinking - Interocular symmetry and asymmetry in neurovascular patterning, in health and disease

No biological system or structure is likely to be perfectly symmetrical, or have identical right and left forms. This review explores the evidence for eye and visual pathway asymmetry, in health and in disease, and attempts to provide guidance for those studying the structure and function of the visual system, where recognition of symmetry or asymmetry may be essential. The principal question with regards to asymmetry is not 'are the eyes the same?', for some degree of asymmetry is pervasive, but 'when are they importantly different?'. Knowing if right and left eyes are 'importantly different' could have significant consequences for deciding whether right or left eyes are included in an analysis or for examining the association between a phenotype and ocular parameter. The presence of significant asymmetry would also have important implications for the design of normative databases of retinal and optic nerve metrics. In this review, we highlight not only the universal presence of asymmetry, but provide evidence that some elements of the visual system are inherently more asymmetric than others, pointing to the need for improved normative data to explain sources of asymmetry and their impact on determining associations with genetic, environmental or health-related factors and ultimately in clinical practice.

Performance, usability and comparison of two versions of a new macular vision test: the handheld Radial Shape Discrimination test

Background

Central vision, critical for everyday tasks such as reading and driving, is impacted by age-related changes in the eye and by diseases such as age-related macular degeneration. The detection of changes in macular function is therefore important. The Radial Shape Discrimination (RSD) test measures the threshold at which distortions in a radial frequency pattern can be detected and there is evidence that it is more sensitive to macular pathology than visual acuity (VA). It also provides a more quantitative measure of macular function than the commonly available Amsler grid. Recently, handheld versions of the test (hRSD) in which stimuli are presented on mobile devices (e.g., Apple iPod Touch, iPhone) have been developed. We investigated the characteristics of the hRSD test in healthy participants.

Methods

Data were collected using both three-alternative forced choice (3AFC) and 4AFC versions of the hRSD test, presented on an Apple iPod Touch. For the 3AFC version, data from a single test session were available for 186 (72 male; mean ± SD age 42 ± 17y; range 16–90y) healthy participants. Test-retest data were available for subgroups of participants (intra-session: N = 74; tests approximately 2 months apart: N = 30; tests 39 months apart: N = 15). The 3AFC and 4AFC versions were directly compared in 106 participants who also completed a usability questionnaire. Distance and near VA and Pelli Robson Contrast Sensitivity (CS) data were collected and undilated fundoscopy performed on the majority of participants.

Results

Mean (±SD) 3AFC hRSD threshold was −0.77 ± 0.14 logMAR, and was statistically significantly correlated with age (Pearson r = 0.35; p < 0.001). The linear regression of hRSD threshold on age had a slope of +0.0026 compared to +0.0051 for near VA (which also correlated with age: r = 0.51; p < 0.001). There were no statistically significant differences in hRSD thresholds for any of the test-retest subgroups. We also observed no statistically significant difference between 3AFC (−0.82 ± 0.11 logMAR) and 4AFC (−0.80 ± 0.12 logMAR) hRSD thresholds (t = 1.85, p = 0.067) and participants reported excellent test usability with no strong preference expressed between the 3AFC and 4AFC versions of the test.

Discussion

The 3AFC hRSD thresholds we report are consistent with a number of previous studies, as is its greater stability in ageing compared to VA. We have also shown that in the absence of pathology, thresholds are stable over short and long timescales. The 4AFC thresholds we have reported provide a baseline for future investigations, and we have confirmed that 3AFC and 4AFC thresholds are similar, providing a basis of comparisons between studies using the different versions. As the hRSD test is easy to use and relatively inexpensive, clinical studies are now required to establish its ability to detect and monitor macular pathologies.

Spectral-domain optical coherence tomography findings of the macula in 500 consecutive patients with uveitis

PurposeTo analyze the macular structure in a large series of consecutive patients with different types of uveitis using spectral-domain optical coherence tomography (SD-OCT).Patients and methodsFive hundred eyes of 500 consecutive patients with anterior, intermediate, posterior, and panuveitis underwent standardized macular examination using SD-OCT. Central retinal thickness (CRT), macular volume (MV), and presence of cystoid macular edema (CME), diffuse macular edema (DME), serous retinal detachment (SRD), epiretinal membrane with (ERM+) and without (ERM-) retinal surface wrinkling were determined.ResultsThe anatomic location of inflammation affected significantly CRT and MV (P<0.001, respectively), with the highest values in intermediate and panuveitis. CME was seen in 25% of all uveitic eyes, DME in 11%, SRD in 8%, ERM+ in 18%, and ERM- in 13%. CME was most frequent in intermediate (40%) and panuveitis (36%); DME was most frequent in panuveitis (18%) and posterior uveitis (17%); SRD was most frequent in panuveitis (15%) and posterior uveitis (10%); ERM+ was most frequent in panuveitis (45%) and intermediate uveitis (30%); and ERM- was most frequent in intermediate (14%) and posterior uveitis (15%).ConclusionSD-OCT of the macula is recommended for all uveitis patients. CRT, MV, and the incidence of CME were highest in intermediate and panuveitis.

Electroretinographic and optical coherence tomography findings in breast cancer patients using aromatase inhibitors

BACKGROUND

The present cross-sectional study has the purpose to investigate the impact of aromatase inhibitors (AIs) on retinal nerve fiber layer (RNFL) thickness, optic nerve and macular function in patients using AIs for breast cancer treatment.

METHODS

Participants in our study were 41 hormone-receptor-positive earlystage breast cancer patients who were treated with AIs in the adjuvant setting. Moreover, 40 age- and gender-matched control subjects, having neither ocular nor systemic disorders, were included in this study. All participants underwent a complete ophthalmological examination, including best corrected visual acuity (BCVA) assessment, RNFL thickness and central foveal thickness (CFT) measurement, visual evoked potentials (VEP) recording and multifocal-electroretinogram (mf-ERG) recording. Univariate and multiple regression analyses were performed.

RESULTS

At the multiple regression analyses, patients receiving AIs presented with lower average RNFL and inferior RNFL. Moreover, similarly to the univariate analysis, intake of AIs was associated with lower amplitude P100, lower retinal response density in ring 1 and ring 2, longer peak time P100 and longer P1 time in ring 1.

CONCLUSION

Our study is the first in the literature investigating the potential effect of AIs on RNFL thickness, optic nerve and macular function in patients using AIs for breast cancer treatment. The principal message of our study is that patients using AIs exhibited a significant decrease in RNFL thickness (average, superior and inferior), retinal response density and visual acuity compared to healthy controls, while VEP findings (both amplitude and peak time of P100) differ significantly as well.