Risk of Airborne COVID-19 Transmission While Performing Humphrey Visual Field Testing.

PRECIS: Designing and demonstrating an experiment that shows the risk of airborne transmission of COVID-19 between patients having visual fields analyzed is low. PURPOSE: The aim was to investigate the possibility of airborne transmission of COVID-19 during Humphrey visual field testing in a real-world scenario. METHODS: A particle counter was placed within the bowl of Humphrey visual field analyzer (HFA) before and after turning on the machine to ascertain the effect of the air current produced by the ventilation system on aerosols. A second experiment was run where the particle counter was placed in the bowl and recorded particulates, in the air, as a 24-2 SITA standard was performed by a mock patient and then again immediately after the patient had moved away. We measured aerosol particle counts sized ≤0.3 µm, >0.3≤0.5 µm, >0.5≤1 µm, >1≤2.5 µm, >2.5≤5 µm, and >5≤10 µm. RESULTS: Particulates of all sizes were shown to be significantly reduced within the bowl after turning the machine on, demonstrating that the air current produced by the HFA pushes air out of the bowl and it cannot stagnate. There was no significant difference in measurement of aerosol while there was a patient performing the test and immediately after they had moved away, suggesting that aerosols breathed out by the patient are not able to remain in suspension in the bowl because of the ventilation current. CONCLUSION: There is no significant difference between aerosol count in the bowl of a HFA before, during and after testing. This suggests the risk of airborne transmission of COVID-19 is low between subsequent patients. This is in keeping with manufacturer's guidance on Humphrey visual field testing.

Accelerated Pulsed High-Fluence Corneal Cross-Linking for Progressive Keratoconus.

PURPOSE: To report on 2-year results of accelerated corneal collagen cross-linking (CXL) in progressive ectasia using the Avedro KXL system. DESIGN: Prospective interventional case series. METHODS: A total of 870 patients (1,192 eyes) attending Moorfields Eye Hospital after CXL were included. All patients undergoing CXL had progressive keratoconus. Corneas with a minimum stromal thickness <375 µm were excluded. Riboflavin 0.1% soak duration was 10 minutes. High-fluence pulsed UVA was delivered at 30 mW/cm2 for 4 minutes, with a 1.5-second on/off cycle (total energy 7.2 J/cm2). Subjective refractive, corneal tomography, and specular microscopy were performed at baseline, 6, 12, and 24 months postoperatively. The primary outcome measure was a change in maximum keratometry (Kmax) at 24 months. RESULTS: Twelve- and 24-month follow-up data were available on 543 and 213 patients, respectively (mean age 25.4 ± 6.6 years). In mild cones (Kmax < 55 diopter [D]), mean keratometry remained unchanged at 24 months. In more advanced disease, we observed modest corneal flattening compared to baseline (Kmax 63.2 ± 6.5 D vs 61.9 ± 8.1 D, P = .02), but no significant changes in central keratometry (K1 or K2). Keratometric stabilization was confirmed in 98.3% of eyes. Mean CDVA, manifest refraction and endothelial cell density did not change. Overall, 2.7% of eyes lost more than 2 lines of CDVA. CONCLUSION: Accelerated pulsed CXL is a safe, effective, and refractively neutral intervention (at 2 years) to halt disease progression in keratoconus.

Comparison of the Endosaver with noninjector techniques in Descemet's stripping endothelial keratoplasty.

PURPOSE: Minimal loss of corneal endothelial cells during corneal transplantation is a major target but remains a point of controversy among specialists. Hence, the available method to best achieve this continues to stir progress in the field. The aim of this study is to evaluate the use of the Endosaver injector device for graft insertion in Descemet's stripping endothelial keratoplasty (DSEK) and compare the visual outcomes and endothelial cell survival between the Endosaver injector and Goosey grasping forceps insertion techniques. METHODS: This was a retrospective, interventional, consecutive case series undertaken at the University of Southampton Eye Department to assess outcomes of DSEK using the Endosaver injector device compared to noninjector DSEK insertion. Postoperative specular microscopy alongside manifest refraction at 6 and 12 months was evaluated and compared. Mann-Whitney U-test was employed for the statistical analysis of data. RESULTS: Both the Endosaver and Goosey forceps groups showed an improvement in best corrected visual acuity. No significant statistical difference was found in preoperative and postoperative best-corrected visual acuity between the Endosaver and non-Endosaver insertion groups. Mean preoperative endothelial cell count was 2660 (±130) for the Endosaver group and 2608 (±66) for the non-Endosaver group. Postoperative endothelial counts at 6 and 12 months showed a significant difference between the Endosaver: 2104 (±199)-1896 (±226) and the non-Endosaver: 1492 (±207)-1314 (±224) (P < 0.005) groups, respectively. CONCLUSION: The Endosaver injection device is associated with less trauma to endothelium during graft insertion due to the minimal touch technique employed. A smaller insertion wound of 4.0 mm compared to noninjector cases enabled a more stable system during surgery with no or minimal anterior chamber shallowing. The combination of a stable host with minimal endothelial graft handling and subsequent trauma potentially leads to higher endothelial cell counts when the Endosaver injection device is used compared to forceps insertion.

In Vitro Study of the Deturgescence Ability of Cultivated Human Corneal Endothelial Cells.

PURPOSE: To evaluate the efficiency of cultivated human corneal endothelial cells (HCECs) to dehydrate the cornea, using models of the posterior cornea, composed of artificial collagen mass (to represent corneal stroma) and equine collagen membranes (to represent Descemet membrane). METHODS: HCECs were isolated from donor corneal rings and cultivated at 37°C in 5% CO2 and 95% humidified air. The study design included 4 different sets of models: in set 1, the HCECs were placed directly on the collagen mass complex; in set 2, HCECs were placed on a thin equine collagen membrane and laid over the collagen mass; in set 3, HCECs were placed on a thick equine collagen membrane laid over the collagen mass; and in set 4 (the control group), the hydrophilic collagen mass was left alone to interact with the nutritional medium. The minimum thickness of each sample was measured with optical coherence tomography directly before placement of cells and after exposure to the nutritional fluid for 48 hours. RESULTS: After 2 days of exposure to the nutritional medium, the percentage decreases in thickness in "posterior cornea" models were 66% for set 1, 57% for set 2, and 13% set 3. In the control set, measurement of thickness after 2 days of exposure was not possible because of excessive fluid absorption. CONCLUSIONS: This in vitro study of HCECs showed that the dehydrating ability of HCECs is adversely affected by increased thickness of the artificial (Descemet) membrane. Further studies with similar models would aid better understanding of corneal diseases.

Accuracy of the refractive prediction determined by multiple currently available intraocular lens power calculation formulas in small eyes.

PURPOSE: To observe the refractive outcomes of cataract surgery in small adult eyes, and to investigate the accuracy of different intraocular lens (IOL) power prediction formulas. DESIGN: Retrospective interventional case series. METHODS: We included consecutive small eyes undergoing uneventful phacoemulsification cataract surgery with a single highly powerful IOL (Acrysof SA60AT) implanted in the capsular bag (range of powers +35.0 to +40.0 diopters [D]), at the Cataract Centre for Moorfields Eye Hospital. Exclusion criteria were combined or previous intraocular surgical procedures, and any type of intraoperative complications. Main outcome measures were mean prediction errors with Hoffer Q, Holladay 1, Holladay 2, Haigis, SRK-T, and SRK-II IOL power prediction formulas and proportions of eyes achieving absolute errors within the dioptric ranges of 0.5, 1.0, and 2.0 D of target and emmetropia, respectively. The ANOVA test was used to compare the refractive results among various formulas. RESULTS: Twenty-eight eyes were studied; the mean numerical error was 0.22 ± 1.22 D and the mean absolute error was 0.95 ± 0.78 D with the adopted Hoffer Q formula; 39%, 61%, and 89% of the eyes had a final refraction within 0.5 D, 1.0 D, and 2.0 D of target, respectively. None of the latest-generation formulas significantly outperformed the others (P = .245). CONCLUSIONS: The Hoffer Q formula led to good or fair refractive outcomes in less than two thirds of the cases. With Holladay 1 and 2 and Haigis formulas, outcomes would have not been significantly different. The SRK formulas yielded less accurate predictions. Possible reasons are discussed.

The toxic effect of air on primary human retinal pigment epithelium cells.

PURPOSE: To investigate the toxic effect of air on primary human retinal pigment epithelium cells (RPE) over time. METHODS: RPE cultures were retrieved from six donor eyes and cultivated at 37 °C in 5% CO(2) and 95% humidified air. The RPE were divided in six groups with each group containing four samples. Six groups of RPE cultures were set up and four samples were enclosed in each group: group 1 consisted of samples in which RPE were exposed to air for 1 hour. Group 2 consisted of RPE exposed to air for 3 hours, group 3 for 6 hours group 4 for 12 hours group 5 for 24 hours and group 6 for 36 hours respectively. RESULTS: Six hours after exposure, the morphology of the cells was still intact. At 12 hours few cells appeared enlarged. 24 hours after exposure to air the cells started losing their typical morphology and appeared deformed. Viability was higher than 95% in groups 1-3 while for groups 4-6 was 75.5%, 15.5% and 7.3%, respectively. CONCLUSION: The toxic effect of air for the studied in vitro model of RPE is not significant for the first 6 hours. The morphology of the cells progressively changed after 12 hours of exposure and almost all cells appeared apoptotic at 36 hours.

Complications and outcomes of phacoemulsification cataract surgery complicated by anterior capsule tear.

PURPOSE: To study the results of phacoemulsification cataract surgery complicated by anterior capsule tear. DESIGN: Retrospective interventional controlled case series. METHODS: Consecutive series of eyes suffering intraoperative anterior capsule tear and others with uneventful cataract surgery at Moorfields Eye Hospital were investigated. Biometric, intraoperative, and postoperative details were recorded. The exclusion criteria were combined surgical procedures, planned manual extracapsular cataract extraction, and history of previous intraocular surgery or eye trauma. The main outcome measures were intraoperative capsule complication rates, refractive and visual outcomes, and incidence of short-term postoperative complications. Two-sided Fisher exact and paired t tests were used for categorical and continuous data, respectively. RESULTS: The study and control groups included 239 and 212 eyes, respectively. In the study group, planned phacoemulsification was converted to manual extraction in 5 cases (2%); a concurrent posterior capsule rupture occurred in 58 eyes (24%) with a rate of nuclear lens material drop in the posterior segment of 5% (11 cases). Over 11% of eyes (n = 27) underwent unplanned secondary surgical procedures. Overall, the refractive outcomes were poor in 22.4% of eyes (postoperative refraction ≥1 diopter of target), and were statistically worse (P < .0001). A significant visual improvement was observed in the majority of the study group eyes (71%); permanent visual loss occurred in 4 eyes (1.7%). CONCLUSIONS: Anterior capsule tear can lead to additional intraoperative complications, with a relatively high incidence of secondary interventions. Overall, permanent visual loss can be observed and worse refractive outcomes are to be expected, particularly if the lens is being implanted out of the bag.

Phacoemulsification using 8 flexible iris hooks in a patient with a short eye, small pupil, and phacodonesis.

UNLABELLED: We describe a technique that uses flexible iris hooks to dilate and stabilize the capsular bag in a patient with a very deep set and small eye, narrow palpebral fissure, shallow anterior chamber, and very small pupil, who was scheduled for routine phacoemulsification for a white cataract. At the time of iris hook placement, the capsular bag was noted to be markedly unstable. The patient was managed successfully with phacoemulsification of the lens using 4 iris hooks to dilate the pupil and 4 iris hooks to stabilize the capsular bag during surgery. A foldable posterior chamber 3-piece intraocular lens was fixated in the ciliary sulcus. FINANCIAL DISCLOSURE: Neither author has a financial or proprietary interest in any material or method mentioned.