Comparison of Ectasia Detection in Early Keratoconus Using Scheimpflug-Based Corneal Tomography and Biomechanical Assessments.

PURPOSE: The aim of this study was to determine the detection of keratoconus using corneal biomechanical parameters only, a corneal tomographic parameter only, and a parameter that combines corneal biomechanical and tomographic indices. METHODS: The discriminatory power of the Pentacam Random Forest Index (PRFI), Belin/Ambrósio Enhanced Ectasia Display (BAD-D) index, Corvis Biomechanical Index (CBI), and Tomographic and Biomechanical Index (TBI) to differentiate between normal eyes (n = 84), eyes with very asymmetric corneal ectasia (VAE-E, n = 21), and the fellow eyes without apparent ectasia based on normal tomography (VAE-NT, n = 21) was assessed. Statistical analyses were completed with R software using t -tests, Wilcoxon rank sum tests, and receiver operating characteristic (ROC) curves. The DeLong test was used to compare the area under the ROC curve (AUROC). RESULTS: The TBI and PRFI had the highest AUROC when distinguishing between normal and VAE-E corneas (AUROC = 1.00, 95% CI = 1.00-1.00); however, they were not statistically superior to the CBI (AUROC = 0.97, P = 0.27) or BAD-D (AUROC = 1.00, P = 0.34). The TBI (AUROC = 0.92, 95% CI = 0.86-0.98) was superior to CBI (AUROC = 0.78, P = 0.02) and BAD-D (AUROC = 0.81, P = 0.02) when distinguishing between healthy and VAE-NT corneas. At a threshold of 0.72, the TBI had 99% sensitivity, 67% specificity, and 92% accuracy in distinguishing normal and VAE-NT corneas. CONCLUSIONS: The TBI is a useful parameter for the screening of subclinical and frank keratoconus in tomographically normal eyes.

Ophthalmic surgery in New Zealand: analysis of 410,099 surgical procedures and nationwide surgical intervention rates from 2009 to 2018.

BACKGROUND: Surgical intervention rates (SIR) provide a proxy measure of disease burden, surgical capacity, and the relative risk-benefit ratio of surgery. The current study assessed decade trends in ophthalmic surgery and calculated SIRs for all major classes of commonly performed ophthalmic procedures in New Zealand. METHODS: Retrospective population-based analysis of all ophthalmic surgical procedures performed in New Zealand from 2009 to 2018. National and regional datasets from public and private health sectors and industry were analysed. SIRs were calculated for all major ophthalmic procedures, and subgrouped by patient demographics. RESULTS: There were 410,099 ophthalmic surgical procedures completed with a 25.3% overall increase over 10 years. Procedures were mostly government-funded (51%, n = 210,830) with 71% of patients aged over 64 years. Cataract surgery (78%, n = 318,564) had the highest mean SIR (703/100,000/year) and increased by 25% during the study period, consistent with population growth in the over 64 years old age group. Vitrectomy surgery had the second highest mean SIR (67/100,000/year) and increased by 50%, well above national population growth during the study period. Other SIRs included conjunctival lesion-biopsy (38/100,000/year), glaucoma (33/100,000/year), strabismus (20/100,000/year), dacryocystorhinostomy (10/100,000/year), and keratoplasty surgery (4/100,000/year). CONCLUSIONS: This comprehensive review of New Zealand ophthalmic surgery reports increasing SIRs that cannot be explained by population growth alone. Cataract surgery numbers increased year on year consistent with the increase in the over 64 years old population. Vitrectomy surgery growth exceeded that of the national population, including those over 64 years.

Validation of Mahajan's formula for scaling ocular higher-order aberrations by pupil size.

Purpose: Zernike polynomials for describing ocular higher order aberrations are affected by pupil aperture. The current study aimed to validate Mahajan's formula for scaling Zernike polynomials by pupil size. Methods: Higher order aberrations for 3 intraocular lens models (AcrySof IQ IOL SN60WF, Technis ZA9003, Adapt Advanced Optics) were measured using the Zywave aberrometer and a purpose-built physical model eye. Zernike coefficients were mathematically scaled from a 5 mm to a 3 mm pupil diameter (5:3 mm), from a 5 mm to a 2 mm pupil diameter (5:2 mm), and from a 3 mm to a 2 mm pupil diameter (3:2 mm). Agreement between the scaled coefficients and the measured coefficients at the same pupil aperture was assessed using the Bland-Altman method in R statistical software. Results: No statistically significant mean difference (MD) occurred between the scaled and measured Zernike coefficients for 21 of 23 analyses after Holm-Bonferroni correction (P > 0.05). Mean differences between the scaled and measured Zernike coefficients were clinically insignificant for all aberrations up to the fourth order, and within 0.10 µm. Oblique secondary astigmatism (Z-24) was significantly different in the 5:3 mm comparison (MD = -0.04 µm, P < 0.01). Horizontal coma (Z13) was significantly different in the 3:2 mm comparison (MD = -0.07 µm, P = 0.03). There were borderline statistical differences in both vertical (Z-13) and horizontal coma (Z13) in the 5:3 mm comparison (MD = 0.02 µm, -0.09 µm, P = 0.05, 0.05, respectively). Conclusion: A formula for the scaling of higher order aberrations by pupil size is validated as accurate. Pupil scaling enables accurate comparison of individual higher order aberrations in clinical research for situations involving different pupil sizes.

New Zealand adult ocular trauma study: A 10-year national review of 332 418 cases of ocular injury in adults aged 18 to 99 years.

IMPORTANCE: Ocular injury is a common, preventable cause of temporary and permanent disability. BACKGROUND: The current study evaluates the nationwide incidence, demographics and visual outcomes of adults with ocular injury in New Zealand. DESIGN: Nationwide retrospective review. PARTICIPANTS: New Zealanders aged 18-99 years from 2007 to 2016 with ocular injury requiring assessment by a registered medical practitioner. METHODS: New Zealand national and regional datasets were used to evaluate population-level statistics over a 10-year period. Visual and clinical outcome data were assessed using a random sample of 150 patients from a tertiary hospital. MAIN OUTCOME MEASURES: Annual incidence, aetiology, demographics, injury location, visual outcomes, protective eyewear use, surgical intervention and follow-up. RESULTS: A total of 332 418 adult eye injuries were recorded nationally. The annual incidence of eye injury was 1007/100 000 population/year. Patients were predominantly male (76.1%), of New Zealand-European ethnicity (74.6%) and aged between 20 and 29 years (21.1%). The most common mechanism of injury was "struck by object" (55.4%). Injuries occurred most commonly at home (48.4%), followed by commercial (15%) and industrial locations (13.8%). Injuries were more common in rural regions (P < .001). Protective eyewear use was reported in 6% of cases (n = 9, 95% confidence interval = 3.2-11.0). Most ocular injuries were managed exclusively in primary care (70.5%). CONCLUSIONS AND RELEVANCE: Adults with the highest risk of ocular injury are rural males aged 20 to 29 years. Protective eyewear use is uncommon in adults presenting with ocular injury and the majority of injuries are managed in primary care. Promotion of appropriate injury prevention strategies is an important public health message.

Corneal Curvature: the Influence of Corneal Accommodation and Biomechanics on Corneal Shape.

PURPOSE: Variation in the presence and magnitude of corneal conformational changes during accommodation may predict postoperative ectasia following refractive surgery and assist in the early diagnosis of corneal ectatic disorders. The current study aimed to establish a baseline for corneal refractive changes during ocular accommodation and to clarify the role of biomechanical factors in predicting these changes in a population without corneal pathology. METHODS: GALILEI G2 corneal tomography was assessed in 63 participants in both the accommodated and unaccommodated states. Four diopters (D) of physiological accommodation were induced using near-acuity calibrated words viewed through an externally mounted beam splitter mounted on a three-dimensional-printed frame. Corneal biomechanical characteristics were assessed with the CorVis-ST instrument, and statistical analysis was completed in R software. RESULTS: Anterior chamber depth was reduced by 0.10 ± 0.07 mm with accommodation (P < 0.01). Areas of statistically significant change in corneal curvatures were seen in all participants with accommodation. Mean anterior instantaneous corneal power increased in the superior-nasal periphery (0.1 D, 95% confidence interval [CI] = 0.05-0.2 D) and decreased in the inferior-temporal periphery (0.1 D, 95% CI = -0.05 to -0.15 D). Corneal stiffness and the corneal deformation amplitude ratio predicted peripheral corneal curvature changes with accommodation (P < 0.05). CONCLUSION: Corneal conformational changes occur during accommodation in normal subjects. Further studies are required to assess the magnitude of corneal changes during accommodation in patients with corneal ectasia. TRANSLATIONAL RELEVANCE: An externally mounted beam splitter can be used to modify the visual target presented by clinical ocular imaging instruments. Corneal conformational changes during accommodation may be useful in the diagnosis of corneal ectasia.

Comparison of higher order wavefront aberrations with four aberrometers.

Purpose: To evaluate the agreement of selected higher order aberration measurements between aberrometers based on three different wavefront technologies. Methods: Twenty-three eyes of 23 participants were compared between Zywave, OPD-Scan III, and iDesign aberrometers, for total ocular aberrations. Participants were between 19 and 69 years of age, and exclusion criteria were previous ocular surgery or trauma, contact lens wear within the preceding 2 weeks, and ocular or systemic disease. Corneal aberrations were compared between the OPD-Scan III and GALILEI™ G2 aberrometers. Zernike coefficients of vertical and oblique trefoil, vertical and horizontal coma, and spherical aberration were analyzed in R software. Results: In all, 276 scans were captured in total, with a male-to-female ratio of 11:12. Total ocular vertical coma [mean difference (MD) = 0.026 µm, P < 0.005], vertical trefoil (MD = 0.033 µm, P < 0.05), and spherical aberration (MD = 0.022 µm, P < 0.05) differed significantly between the iDesign and OPD-Scan III. Differences in total vertical (MD = 0.072 µm, P < 0.05) and oblique trefoil (MD = 0.058 µm, P < 0.05) were demonstrated between the Zywave and OPD-Scan III, and spherical aberration (MD = 0.030 µm, P < 0.005) between iDesign and Zywave. iDesign corneal horizontal coma (MD = 0.025 µm, P < 0.05) and spherical aberration (MD = 0.043 µm, P < 0.005) measurements were significantly different between the GALILEI™ G2 and the OPD-Scan III. Conclusion: Zywave, iDesign, and OPD-Scan III, and GALILEITM G2 and OPD-Scan III may be used interchangeably for their total ocular and corneal wavefront functions, respectively; however, care must be taken if using these devices for guiding ablation or monitoring corneal disease.

Biomechanical changes in the cornea following cataract surgery: A prospective assessment with the Corneal Visualisation Scheimpflug Technology.

IMPORTANCE: Intraocular pressure (IOP) is often reduced following cataract surgery. Postoperative changes in corneal stiffness are likely to be at least partly responsible for any reduction in IOP measured with applanation tonometry. BACKGROUND: To determine the effect of cataract surgery and corneal incision size on corneal biomechanics. DESIGN: Prospective randomized trial. PARTICIPANTS: One hundred prospectively enrolled patients qualifying for cataract surgery. METHODS: Participants were randomized to clear corneal incisions with a 2.20 or 2.85 mm keratome. Corneal Visualisation Scheimpflug Technology (Corvis-ST) tonometry and dynamic corneal response measurements were obtained preoperatively, and 3 mo postoperatively. Multiple regression analysis was completed using R software. MAIN OUTCOME MEASURES: Corvis-ST biomechanical parameters. RESULTS: Ninety-three eyes of 93 patients were included in the final analysis. Mean Corvis-ST biomechanically corrected IOP decreased by 3.63 mmHg postoperatively (95% confidence interval = 2.97-4.35, P ≤ 0.01), and central pachymetry increased by 6.96 µm (4.33-9.59, P ≤ 0.01). Independent of IOP and pachymetry changes, mean (±SE) corneal first applanation stiffness parameter reduced by 9.761 ± 3.729 (P = 0.01) postoperatively. First applanation velocity increased by 0.007 ± 0.002 ms, second applanation velocity increased by 0.012 ± 0.004 ms (P ≤ 0.01), the first applanation deformation amplitude increased by 0.008 ± 0.002 mm (P ≤ 0.01) and the deflection amplitude at highest concavity increased by 0.030 ± 0.069 (P ≤ 0.01). There were no significant differences between different incision size groups. CONCLUSIONS AND RELEVANCE: Corneal stiffness is reduced 3 mo following cataract surgery and is associated with falsely low IOP measurements. This finding may be important for glaucoma patients and in particular when assessing the effectivity of minimally invasive glaucoma surgery devices.

Auckland Cataract Study III: Refining Preoperative Assessment With Cataract Risk Stratification to Reduce Intraoperative Complications.

PURPOSE: To assess intraoperative complications of phacoemulsification surgery in public teaching hospital settings using modified preoperative risk stratification systems. DESIGN: Prospective cohort study. METHODS: Preoperative risk stratification of 500 consecutive cataract cases using the New Zealand Cataract Risk Stratification (NZCRS) scoring system. Recommended allocation of higher-risk phacoemulsification procedures to experienced surgeons in public teaching hospital setting. MAIN OUTCOME MEASURE: Intraoperative complications relative to adherence to stratification recommendations. RESULTS: NZCRS classified 192 cases (38%) as high-risk, recommended for fellows or consultants (attendings). Primary surgeons were residents (n = 142, 28%), fellows (n = 88, 18%), and consultants (n = 270, 54%). Overall rate (N = 500) of any intraoperative complication was 5.0%. Where NZCRS scoring recommendations were observed (n = 448) the intraoperative complication rate was 4.5% but in "nonadherence" cases (n = 52 residents operating on higher-risk cases) this nearly doubled (9.6%). Postoperative complications occurred in 5.2%, primarily cystoid macular edema (3.7%). Postoperatively, mean unaided visual acuity was 6/12 (20/40) and best-corrected visual acuity improved from 6/20 (20/63) preoperatively to 6/10 (20/32) postoperatively (P < .05). CONCLUSIONS: The NZCRS system aids identification of higher-risk cataract cases and appropriate case-to-surgeon allocation and may increase surgeon awareness of risk factors. Compared to 2 previous studies under similar conditions in the same institution, the NZCRS system was associated with a 40% reduction in intraoperative complications (8.4% to 5%). The rate of posterior capsular tear was 0.6% (P = .035) compared to 2.6% in baseline phase and 1.4% in a prior risk stratification phase. Risk stratification seems to reduce intraoperative phacoemulsification complications in public teaching hospital settings.

Effect of phacoemulsification incision size on incision repair and remodeling: Optical coherence tomography assessment.

PURPOSE: To characterize the effect of incision size on corneal incision repair and remodeling over 3 months after cataract surgery. SETTING: Department of Ophthalmology, Auckland District Health Board, Auckland, New Zealand. DESIGN: Prospective case series. METHODS: Eyes having routine cataract surgery were randomized to receive 2.20 mm or 2.85 mm uniplanar clear corneal incisions. Anterior segment optical coherence tomography of incision thickness, length, width, gaping, and angle and specular microscopy of endothelial cell density (ECD), polymegathism, and pleomorphism were completed at baseline and 1, 7, 30, and 90 days postoperatively. RESULTS: Each incision group comprised 50 eyes (50 patients). Ninety-nine patients (99%) attended all assessments. The Descemet membrane detachment rate was greater than 50% with 2.20 mm incisions (P = .01). Patients with Descemet membrane detachments had increased endothelial wound gaping, slower visual recovery, and increased corneal thickness at the incision site at all visits (φ = 0.54, P < .01). The 2.20 mm group had greater polymegathism despite no difference in the mean phacoemulsification energy between groups (2.20 mm: 32.3% ± 6.2% [SD]; 2.85 mm: 30.8% ± 6.5%) (P = .02). Ninety days postoperatively, the 2.20 mm group had a lower mean ECD (2195 ± 360 cells/mm2) than the 2.85 mm group (2397 ± 335 cells/mm2) (P = .01). Final visual acuity, gaping, and angles were not significantly different between the groups. CONCLUSIONS: The 2.20 mm wide corneal incisions were more prone to trauma than 2.85 mm incisions during routine cataract surgery. Corneal incisions with signs of trauma were associated with prolonged visual recovery and slower healing postoperatively.

Predicting pseudophakic refractive error: Interplay of biometry prediction error, anterior chamber depth, and changes in corneal curvature.

PURPOSE: To quantify pseudophakic refractive error prediction with the Hill-RBF, Barrett Universal II, and SRK/T formulas and to evaluate the temporal effects of anterior chamber depth (ACD) and keratometric changes on postoperative refraction. SETTING: Department of Ophthalmology, University of Auckland and Auckland District Health Board, Auckland, New Zealand. DESIGN: Prospective case series. METHODS: Patients listed for cataract surgery were prospectively recruited. Optimum intraocular lens (IOL) power and predicted refractive outcomes were calculated, and the predicted refraction was compared with objective refractive outcomes at 1-week and 1-month and 3-month follow-ups. RESULTS: The study comprised 100 patients (100 eyes). The mean axial length was 23.4 mm ± 1.1 (SD). The mean keratometry was 43.9 ± 1.3 diopters (D). The mean absolute prediction errors at 3-months were: Universal II: 0.50 ± 0.46 D, RBF: 0.49 ± 0.43 D, and SRK/T: 0.52 ± 0.49 D. The Universal II formula was better than all other methods at 1 week (P = .02); no method was superior at 1 month (P = .46) or 3 months (P = .37). The RBF method predicted the highest proportion of eyes within ±0.25 D at 3 months. Keratometric changes primarily occurred 1 to 4 weeks postoperatively (P = .03) and trended toward corneal steepening (+0.11 D, P < .01). A significant mean hyperopic shift occurred 4 to 12 weeks postoperatively (+0.18 D, P < .01), accompanied by a trend toward increasing ACD (+0.04 mm, P = .03). CONCLUSIONS: The Universal II and RBF methods were better than SRK/T in medium length eyes (22 to 24.5 mm). It might be prudent to expect a progressive hyperopic shift in the 3 months after surgery because of posterior IOL migration.

A brief treatment for fear of heights.

Objective To assess the effectiveness of a novel imaginal intervention for people with acrophobia. Methods The design was a randomized controlled trial with concealed randomization and blinded to other participants' intervention. The intervention was a single novel imaginal intervention session or a 15-min meditation. The setting was in Auckland, New Zealand. The participants were a convenience sample of the public with a score >29 on the Heights Interpretation Questionnaire (HIQ), a questionnaire validated against actual height exposure. The primary outcomes were the proportion of participants with a score <26 on the HIQ at eight weeks and difference between the HIQ scores between the two arms of the study. Results Ninety-eight participants (92%) returned their questionnaire and were included in the intention to treat analysis. The HIQ score <26 was 34.6% (18/52) in the intervention group and 15.2% (7/46) in the control group RR = 2.26, 95% CI (1.05, 4.95) and p = 0.028. The numbers needed to treat is six 95% CI (3 to 36). Participants with scores <26 report their fear of heights is very much improved. There was a 4.5-point difference in the HIQ score at eight weeks (p = 0.055) on the multiple regression analysis. Conclusions This is the first randomized trial of this novel imaginal intervention which is probably effective, brief, easily learnt, and safe. It may be worth considering doing this prior to some of the longer or more expensive exposure therapies. This study will be of interest to family doctors, psychiatrists, and psychologists.

A systematic review and meta-analysis of treatments for acrophobia.

OBJECTIVE: To review the literature on the comparative efficacy of psychological, behavioural and medical therapies for acrophobia (fear of heights). DATA SOURCES: Multiple databases were searched through the Cochrane Common Mental Disorders review group on 1 December 2015. DATA SYNTHESIS: The data were extracted independently and were pooled using RevMan version 5.3.5. The main outcome measures were changes from baseline on questionnaires for measurement of fear of heights, such as the Acrophobia Questionnaire (AQ), Attitude Towards Height Questionnaire (ATHQ), and behavioural avoidance tests. Individual and pooled analyses were conducted. Sixteen studies were included. Analysis of pooled outcomes showed that desensitisation (DS) measured by the post-test AQ anxiety score (standardised mean difference [SMD], -1.24; 95% CI, -1.88 to -0.60) and in vivo exposure (IVE) were effective in the short term compared with control (SMD, -0.74; 95% CI, -1.22 to -0.25). IVE was not effective in the long term (SMD, -0.34; 95%CI -0.76 to 0.08) and there were no follow-up data for DS. Virtual reality exposure (VRE) therapy was effective when assessed with the ATHQ but not the AQ. Augmentation of VRE with medication was promising. The number needed to treat (NNT) ranged from 1.4 (95% CI, 1.0 to 2.2) for IVE therapy with oppositional actions (a psychological process) versus waitlist control to an NNT of 6.0 (95% CI, 2.8 to 35.5) for the rapid phobia cure (a neurolinguistic programming technique) versus a mindfulness exercise as the control activity. It was often unclear if there were biases in the included studies. CONCLUSIONS AND RELEVANCE: A range of therapies are effective for acrophobia in the short term but not in the long term. Many of the comparative studies showed equivalence between therapies, but this finding may be due to a type II statistical error. The quality of reporting was poor in most studies.