Microbial keratitis in Southern Malawi: a microbiological pilot study.

OBJECTIVE: Microbial keratitis (MK) is a significant cause of blindness in sub-Saharan Africa. We investigated the feasibility of using a novel corneal impression membrane (CIM) for obtaining and processing samples by culture, PCR and whole-genome sequencing (WGS) in patients presenting with suspected MK in Malawi. METHODS AND ANALYSIS: Samples were collected from patients presenting with suspected MK using a 12 mm diameter polytetrafluoroethylene CIM disc. Samples were processed using culture and PCR for Acanthamoeba, herpes simplex virus type 1 (HSV-1) and the bacterial 16S rRNA gene. Minimum inhibitory concentrations of isolates to eight antimicrobials were measured using susceptibility strips. WGS was used to characterise Staphylococcus aureus isolates. RESULTS: 71 eyes of 71 patients were included. The overall CIM isolation rate was 81.7% (58 positive samples from 71 participants). 69 (81.2%) of isolates were Gram-positive cocci. Coagulase-negative Staphylococcus 31.8% and Streptococcus species 14.1% were the most isolated bacteria. Seven (9.9%) participants were positive for HSV-1. Fungi and Acanthamoeba were not detected. Moxifloxacin and chloramphenicol offered the best coverage for both Gram-positive and Gram-negative isolates when susceptibility was determined using known antimicrobial first quartile concentrations and European Committee on Antimicrobial Susceptibility Testing breakpoints, respectively. WGS identified known virulence genes associated with S. aureus keratitis. CONCLUSIONS: In a resource-poor setting, a CIM can be used to safely sample the cornea in patients presenting with suspected MK, enabling identification of causative microorganisms by culture and PCR. Although the microbiological spectrum found was limited to the dry season, these preliminary results could be used to guide empirical treatment.

Ocular phenotype and therapeutic interventions in keratitis-ichthyosis-deafness (KID) syndrome.

BACKGROUND: To report ocular manifestations, clinical course, and therapeutic management of patients with molecular genetically confirmed keratitis-ichthyosis-deafness syndrome. METHODS: Four patients, aged 19 to 46, with keratitis-ichthyosis-deafness syndrome from across the UK were recruited for a general and ocular examination and GJB2 (Cx26) mutational analysis. The ocular examination included best-corrected visual acuity, slit-lamp bio-microscopy, and ocular surface assessment. Mutational analysis of the coding region of GJB2 (Cx26) was performed by bidirectional Sanger sequencing. RESULTS: All four individuals had the characteristic systemic features of keratitis-ichthyosis-deafness syndrome. Each patient was found to have a missense mutation, resulting in the substitution of aspartic acid with asparagine at codon 50 (p.D50N). Main ophthalmic features were vascularizing keratopathy, ocular surface disease, hyperkeratotic lid lesions, recurrent epithelial defects, and corneal stromal scarring. One patient had multiple surgical procedures, including superficial keratectomies and lamellar keratoplasty, which failed to prevent severe visual loss. In contrast, oral therapy with ketoconazole stabilized the corneal and skin disease in two other patients with keratitis-ichthyosis-deafness syndrome. The patient who underwent intracorneal bevacizumab injection showed a marked reduction in corneal vascularization following a single application. CONCLUSIONS: Keratitis-ichthyosis-deafness syndrome is a rare ectodermal dysplasia caused by heterozygous mutations in GJB2 (Cx26) with a severe, progressive vascularizing keratopathy. Oral ketoconazole therapy may offer benefit in stabilizing the corneal and skin disease.

VERTICAL AND HORIZONTAL METAMORPHOPSIA ONE YEAR AFTER SURGERY FOR MACULAR HOLES ≤ 500 µ m WITH AND WITHOUT INVERTED INTERNAL LIMITING MEMBRANE FLAP.

PURPOSE: To investigate the effect of an inverted internal limiting membrane flap (IF) and other factors on metamorphopsia after macular hole surgery. METHODS: Prospective case series of patients undergoing pars plana vitrectomy with gas tamponade, with either conventional internal limiting membrane peeling (CP) or an IF, for primary idiopathic macular holes ≤ 500 µ m. Vertical and horizontal metamorphopsia were measured as M-scores (degrees) using M-charts preoperatively and at 2, 6, and 12 months postoperatively. RESULTS: Fifty-three eyes of 53 patients were included of whom 27 underwent CP and 26 were treated with an IF. After macular hole surgery, all patients were pseudophakic. Vertical and horizontal metamorphopsia improved from 1.08 (±0.51) and 0.98 (±0.70) preoperatively to 0.58 (±0.37) and 0.45 (±0.36) at 2 months ( P < 0.01), with no further significant improvement at 6 months (0.39 [±0.31], P = 0.07 and 0.31 [±0.28], P = 0.18) or at 12 months (0.37 [±0.30], P = 0.72 and 0.28 [±0.28], P = 0.99). There was no significant difference in the mean vertical and horizontal metamorphopsia between patients with CP and with an IF at 2 months ( P = 0.063, P = 0.10), 6 months ( P = 0.25, P = 0.16), or 12 months ( P = 0.62, P = 0.22). Preoperative vertical M-score improved at 12 months after macular hole surgery by 61% and 64% in the CP and IF groups, respectively ( P = 0.84), and the horizontal M-score by 65% and 71%, respectively ( P = 0.98). CONCLUSION: The use of an IF has no evident bearing on the degree of postoperative metamorphopsia 12 months after surgical repair of macular holes ≤ 500 µ m.

Preoperative surgeon evaluation of corneal endothelial status: the Viability Control of Human Endothelial Cells before Keratoplasty (V-CHECK) study protocol.

INTRODUCTION: The success of keratoplasty strongly depends on the health status of the transplanted endothelial cells. Donor corneal tissues are routinely screened for endothelial damage before shipment; however, surgical teams have currently no means of assessing the overall viability of corneal endothelium immediately prior to transplantation. The aim of this study is to validate a preoperative method of evaluating the endothelial health of donor corneal tissues, to assess the proportion of tissues deemed suitable for transplantation by the surgeons and to prospectively record the clinical outcomes of a cohort of patients undergoing keratoplasty in relation to preoperatively defined endothelial viability. METHODS AND ANALYSIS: In this multicentre cohort study, consecutive patients undergoing keratoplasty (perforating keratoplasty, Descemet stripping automated endothelial keratoplasty (DSAEK), ultra-thin DSAEK (UT-DSAEK) or Descemet membrane endothelial keratoplasty) will be enrolled and followed-up for 1 year. Before transplantation, the endothelial viability of the donor corneal tissue will be evaluated preoperatively through trypan blue staining and custom image analysis to estimate the overall percentage of trypan blue-positive areas (TBPAs), a proxy of endothelial damage. Functional and structural outcomes at the end of the follow-up will be correlated with preoperatively assessed TBPA values. ETHICS AND DISSEMINATION: The protocol will be reviewed by the ethical committees of participating centres, with the sponsor centre issuing the final definitive approval. The results will be disseminated on ClinicalTrials.gov, at national and international conferences, by partner patient groups and in open access, peer-reviewed journals. TRIAL REGISTRATION NUMBER: NCT05847387.

P27-A149†Liverpool research eye biobank-our exerience of expanding to collect from living donors.

PURPOSE: The Liverpool Research Eye Biobank (LREB) collects tissue for researchers who wish to study a wide range of ophthalmic conditions and develop new and more effective treatments. Historically the LREB has collected whole globes and conjunctiva from cadaveric donors but in 2021 we expanded to start collecting tissues from living donors who were undergoing ophthalmic surgery in the St Paul's Eye Unit in Liverpool. The aim was to provide tissue and fluid samples from patients with specific eye disease to research projects and create a bank of ophthalmic samples that can be provided to future research projects. Here we reflect on our experience after a year of collections. METHODS: The clinical team discuss donation with patients during the pre-op appointment. Consent is taken on the day of surgery using an electronic consent form available on PENS. Samples are taken according to the patient's consent preference and then stored appropriately within a fridge/freezer close to theatre. Samples are then transferred for processing to the University of Liverpool (UoL). Fluids such as aqueous and vitreous are preserved at -80°C. The majority of ocular tissue collected is preserved by fixing in 10% neutral buffered formalin then transferred to 70% ethanol for long term storage. On request samples have been preserved using alternative methods such as snap freezing in liquid nitrogen. All samples are logged using a laboratory information management system. RESULTS: Collections depend on the cooperation of the clinical teams and we have had very good engagement from them. The UoL works closely with St Pauls Eye Unit and the physical proximity between the two has been helpful. The location of the storage fridges close to theatre is important to limit extra effort for busy clinical teams. Regular training of consenters was key to ensure compliance with SOPs. In 11 months, we consented 419 donors and collected 673 samples including corneal tissue, iris, sclera, lens/capsule, retinal membranes, tenons, muscle, aqueous, vitreous, blood. CONCLUSION: After the success of collections from one site we plan to expand to collect from multiple sites including Aintree and Alder Hey Children's Hospital.

INFLUENCE OF PREOPERATIVE POSTURING ON SUBFOVEAL FLUID HEIGHT IN MACULA-OFF RETINAL DETACHMENTS.

PURPOSE: To evaluate the effect of preoperative posturing on subfoveal fluid height (SFFH) in macula-off retinal detachment. METHODS: A prospective study including patients with macula-off retinal detachment with SFFH measurable on optical coherence tomography (OCT) and duration of loss of central vision (LCV) ≤ 7 days. Linear OCT volume scans were performed at baseline, after 1 minute, 1 hour, 4 hours, and on the next morning. For the first hour, all patients remained in an upright position. Patients were then either instructed to posture until the surgery according to the location of the primary retinal break (posturing group) or were not given any instructions (control group). RESULTS: Twenty-four patients were included in the posturing group and 11 patients in the control group. There was no significant change in SFFH between baseline, 1 minute, 1 hour, and 4 hours. The mean SFFH in the control group increased by 243 µ m from 624 (±268) µ m at baseline to 867 (±303) µ m the next morning ( P < 0.01) but decreased in the posturing group by 150 µ m from 728 (±416) to 578 (±445) µ m ( P = 0.03). There was a significant association of the SFFH the next morning with posturing ( P < 0.01) and SFFH at baseline ( P < 0.01), but not with location of primary break ( P = 0.20). The change in SFFH from baseline to the next morning was significantly associated with posturing and primary break location ( P < 0.01), but not with SFFH at baseline ( P = 0.21). CONCLUSION: Preoperative posturing is an effective measure to prevent progression of macular detachment in macula-off retinal detachment.

Average paraxial power of a lens and visual acuity.

To provide a solution for average paraxial lens power (ApP) of a lens. Orthogonal and oblique sections through a lens of power [Formula: see text] were reduced to a paraxial representation of lens power followed by integration. Visual acuity was measured using lenses of different powers (cylinders of - 1.0 and - 2.0D) and axes, mean spherical equivalent (MSE) of S + C/2, ApP and a toric correction, with the order of correction randomised. A digital screen at 6 m was used on which a Landolt C with crowding bars was displayed for 0.3 s before vanishing. The general equation for a symmetrical lens of refractive index (n), radius of curvature R, in medium of refractive index n1, through orthogonal ([Formula: see text]) and oblique meridians ([Formula: see text]) as a function of the angle of incidence ([Formula: see text]) reduces for paraxial rays ([Formula: see text]) to [Formula: see text]. The average of this function is [Formula: see text] providing a solution of [Formula: see text] for ApP.For central (p = 0.04), but not peripheral (p = 0.17) viewing, correction with ApP was associated with better visual acuity than a MSE across all tested refractive errors (p = 0.04). These findings suggest that [Formula: see text] may be a more inclusive representation of the average paraxial power of a cylindrical lens than the MSE.

Deep Learning Using Preoperative AS-OCT Predicts Graft Detachment in DMEK.

Purpose: To evaluate a novel deep learning algorithm to distinguish between eyes that may or may not have a graft detachment based on pre-Descemet membrane endothelial keratoplasty (DMEK) anterior segment optical coherence tomography (AS-OCT) images. Methods: Retrospective cohort study. A multiple-instance learning artificial intelligence (MIL-AI) model using a ResNet-101 backbone was designed. AS-OCT images were split into training and testing sets. The MIL-AI model was trained and validated on the training set. Model performance and heatmaps were calculated from the testing set. Classification performance metrics included F1 score (harmonic mean of recall and precision), specificity, sensitivity, and area under curve (AUC). Finally, MIL-AI performance was compared to manual classification by an experienced ophthalmologist. Results: In total, 9466 images of 74 eyes (128 images per eye) were included in the study. Images from 50 eyes were used to train and validate the MIL-AI system, while the remaining 24 eyes were used as the test set to determine its performance and generate heatmaps for visualization. The performance metrics on the test set (95% confidence interval) were as follows: F1 score, 0.77 (0.57-0.91); precision, 0.67 (0.44-0.88); specificity, 0.45 (0.15-0.75); sensitivity, 0.92 (0.73-1.00); and AUC, 0.63 (0.52-0.86). MIL-AI performance was more sensitive (92% vs. 31%) but less specific (45% vs. 64%) than the ophthalmologist's performance. Conclusions: The MIL-AI predicts with high sensitivity the eyes that may have post-DMEK graft detachment requiring rebubbling. Larger-scale clinical trials are warranted to validate the model. Translational Relevance: MIL-AI models represent an opportunity for implementation in routine DMEK suitability screening.

Low-Dose Propofol with Peribulbar Anaesthesia for Cataract Surgery.

In this paper, we investigate the effect of sedation using low-dose propofol on patient reported outcome measures (PROMS) in patients undergoing cataract surgery. This is a randomised, single-blinded observational prospective study. Patients undergoing elective cataract surgery using peribulbar anaesthesia over consecutive cataract lists were selected for this trial. Patients were randomised to receive either no sedation or low-dose propofol (20 to 30 mg followed by 10 mg increments until the patient developed slurred speech alone) prior to the administration of local anaesthesia. Pain, satisfaction, anxiety, needle recall, pulse, and blood pressure (BP) were measured. A total of 97 patients were included, 50 of whom received propofol. There were 4 senior surgeons and anaesthetists. There were no ocular or systemic complications and all patients had uncomplicated surgery. Anxiety (p = 0.026), needle recall (p < 0.001), difference in systolic BP (p = 0.043), and pulse (p = 0.046) were dependent on patient age (p < 0.001) and the use of propofol (p = 0.007). Lower pain was associated with propofol (p = 0.008), as well as lower anxiety (p = 0.002), and increased patient age (p = 0.014). The administration of propofol was significantly associated with lower needle recall (p < 0.001), pre- to post-operative difference in systolic BP (p = 0.029), and mean BP (p = 0.044). Low-dose propofol given immediately prior to administration of local anaesthesia was associated with reduced pain and needle recall, as well as lower BP.

Descemet membrane endothelial keratoplasty graft detachments in superior versus temporal approach.

PURPOSE: To evaluate the difference in Descemet Membrane Endothelial Keratoplasty (DMEK) graft detachment rate comparing superior versus temporal main incision approach. METHODS: Retrospective comparative study on patients who underwent DMEK surgery for Fuchs endothelial dystrophy or bullous keratopathy with main wound incision performed at either 90° in the superior approach, or at 180°/0° in the temporal approach. All main incisions were secured with a single 10-0 nylon suture at the end of surgery. Data collected were donor age and gender, endothelial cell counts, graft diameter, recipient age and gender, indication for transplant, surgeon grade, re-bubbling rate, air fill in the anterior chamber (AC) at day one and intra- and early postoperative complications. RESULTS: 187 eyes were included in the study. 99 eyes had DMEK surgery with superior approach, while 88 eyes had temporal approach. The two groups had no differences in donor age and sex, endothelial cell counts, graft diameter, recipient age and sex, indication for transplant, surgeon grade, and air fill in the anterior chamber at day one. Re-bubbling rate was 38.4% for surgeries performed with superior access and 29.5% for those with temporal access(p = 0.186). After exclusion of patients with intraoperative and/or postoperative complication, the difference in re-bubbling rate was higher, although non-significant (37.5% and 25% for superior and temporal approach respectively, p = 0.098). CONCLUSION: The temporal approach in DMEK showed a trend towards a clinically significant lower rate of post-operative re-bubbling compared to the superior approach, however, no statistically significant difference was noted comparing the two approaches, which both remain feasible options in DMEK surgery.

Surgical goniolens for tag identification and removal in DMEK surgery.

INTRODUCTION: We describe a novel technique for identifying endothelial Descemet membrane (DM) tags remaining after descemetorhexis in patients undergoing Descemet membrane endothelial keratoplasty (DMEK) surgery. METHODS: A surgical goniolens is applied to the corneal surface after descemetorhexis in order to visualize the peripheral inner corneal layer at 360° and identify endothelial-DM tags. RESULTS: A detailed visualization of the peripheral inner corneal layer is possible using goniolens, without using any staining in the anterior chamber. CONCLUSION: The technique may be used to screen the posterior corneal surface for any retained endothelial-DM tags. It may to lower the risk of remaining tags and indirectly lower the incidence of DMEK graft detachment.

Binocular visual field in adults with horizontal strabismus and driving requirements.

OBJECTIVE: To determine the horizontal extent of the binocular visual field (BVF) in subjects with horizontal strabismus and whether the BVF falls below the driving standard. METHODS AND ANALYSIS: Adults with congenital esotropia and infantile exotropia ≤45 Prism Dioptres (PD), and subjects with orthotropia were recruited. The manifest angle of deviation was measured using a simultaneous prism cover test. Monocular Visual Field (MVF) and BVF were measured using the Esterman visual field test. Subjects with diplopia or a manifest angle of strabismus that varied by>8PD or the present of a vertical tropia >8PD were excluded. RESULTS: Forty-nine subjects were included: 10 with orthotropia, 20 with exotropia and 19 with esotropia. The horizontal extent of BVF (degrees) was significantly smaller in esotropes (122.8 ± 18.8) than in orthotropes (141 ± 6.6) or exotropes (138.3 ± 8.3) (p < 0.01). In 6 (31.6%) subjects with an esotropia, the BVF was below the driving standard. The horizontal extent of the visual field (VF) of the amblyopic eyes of patients with esotropia (98.70 degrees, SD 19.76) and exotropia (104.75 degrees, SD16.93) were significantly smaller than those with orthotropia (121.00 degrees SD 3.16) by 22.3 degrees (p = 0.004) and 16.25 degrees (p = 0.045), respectively. The difference between the summation of MVFs and the BVF was significantly greater in orthotropes (100.6 ± 2.7) than in exotropes (68.9 ± 34.4) and esotropes (74.2 ± 20.7) (p < 0.01). CONCLUSION: The horizontal extent of BVF is significantly smaller and more variable in adults with congenital esotropia and may fall below the driving standard. STRENGTHS AND LIMITATIONS: Largest study on visual fields in subjects with horizontal strabismus including an orthotropic control group who do not have diplopia and who would otherwise meet the driving standard. Visual field quality was high but limitation is that visual field repeatability was not undertaken. HOW THIS STUDY MIGHT AFFECT RESEARCH, PRACTICE, OR POLICY: The findings of this study would suggest that people with an esotropia should be offered the opportunity to have a binocular visual field test before applying for a driving license. The DVLA may want to consider requesting people with an esotropia to have a binocular visual field test as is a requirement with other ophthalmic conditions such as glaucoma.

Posterior stromal ripples increase risk of Descemet's membrane endothelial keratoplasty graft detachment worsening over time.

PURPOSE: To evaluate anterior segment optical coherence tomography (AS-OCT) features of Descemet's membrane endothelial keratoplasty (DMEK) grafts associated with graft attachment worsening over time. METHODS: Retrospective case series on patients who received uncomplicated DMEK surgery and for whom subsequent AS-OCT data were available for analysis. Patients' demographics and surgical details were collected. AS-OCT was analysed for graft detachment axial extension, presence of posterior stromal ripples, quadrant involvement (location and number), degree of detachment extension, peripheral roll, presence and amount of air in the anterior chamber (AC). Features associated with re-bubbling and graft detachment worsening over time were identified. RESULTS: A total of 147 patients with a mean age of 70.8 ± 9.8 years (63% females) were included. AS-OCT was performed at 2.9 ± 2.4 days after surgery. AS-OCT factors associated with re-bubbling were posterior stromal ripples (p = 0.004) and detachment axial extension (p < 0.001). At first follow-up, of the 147 DMEK, 67 showed complete attachment and 80 partial detachment. In those cases of initially completely attached grafts, posterior stromal ripples were associated with the risk of subsequent graft detachment (p = 0.014) together with recipient age (p = 0.043), phaco-combined surgery (p = 0.018) and AS-OCT timing (p = 0.033); while, in the initially partially detached grafts, detachment worsening was associated with posterior stromal ripples (p = 0.025), detachment axial extension (p = 0.003), degrees of detachment involvement (p = 0.029), peripheral roll-in shape (p = 0.033) and presence of air in the AC (p = 0.032). Relative risk (RR) of graft detachment worsening in patients with moderate/severe posterior stromal ripples was 1.75 (95% CI = 1.09-2.81). CONCLUSION: Posterior stromal ripples and detachment axial extension >1/3 of graft surface area were the main risk factors for detachment worsening over time, and patients showing these features should be monitored closely to identify the need for re-bubbling at an early stage, thus improving surgical outcomes.

Thinning rate over 24 months in ultrathin DSAEK.

AIM: To describe the changes in corneal graft thickness following ultrathin Descemet's Stripping Automated Endothelial Keratoplasty (UT-DSAEK) comparing pre- and postoperative values over a 24-month period. METHODS: In this retrospective single-center case series, patients who received eye bank-prepared tissues for UT-DSAEK surgery were included. Preoperative and postoperative graft thickness measurements were determined in the eye bank and in clinic using anterior segment optical coherence tomography (AS-OCT) images. Graft thickness measurements and their percentage change between preoperative values and values at 1 day, 1 week and 1, 6, 12, 24 months were calculated. RESULTS: In total, 47 eyes of 47 patients with a mean age of 69 ± 11 years (29 males) were included. Twnty-three patients had Fuchs' endothelial dystrophy (49%) and the remaining 24 had pseudophakic bullous keratopathy (51%). In total, 29/47 eyes underwent UT-DSAEK alone (62%) and 18/47 received combined cataract surgery as a triple procedure (38%). Preoperative donor graft thickness was 92 ± 28 µm. Compared to preoperative values, where graft thickness increased to 194 ± 101.3 µm at 1 day, 151.1 ± 71.4 µm at 1 week, and 108.4 ± 52.5 µm at 1 month. Graft thickness continued to gradually decrease over time until 6 months (91.7 ± 33.6 µm), and then plateaued at 12 months (83.9 ± 25.0 µm), showing minimal changes at 2 years (101.4 ± 37.5 µm). CONCLUSION: Preoperative DSAEK graft thickness measurements as reported by the eye bank are a valid approximation of DSAEK graft thickness at 6 months after surgery and these measurements tend to stabilize over time up to 2 years after surgery.

The conjunctival extracellular matrix, related disorders and development of substrates for conjunctival restoration.

The conjunctiva can be damaged by numerous diseases with scarring, loss of tissue and dysfunction. Depending on extent of damage, restoration of function may require a conjunctival graft. A wide variety of biological and synthetic substrates have been tested in the search for optimal conditions for ex vivo culture of conjunctival epithelial cells as a route toward tissue grafts. Each substrate has specific advantages but also disadvantages related to their unique physical and biological characteristics, and identification and development of an improved substrate remains a priority. To achieve the goal of mimicking and restoring a biological material, requires information from the material. Specifically, extracellular matrix (ECM) derived from conjunctival tissue. Knowledge of the composition and structure of native ECM and identifying contributions of individual components to its function would enable using or mimicking those components to develop improved biological substrates. ECM is comprised of two components: basement membrane secreted predominantly by epithelial cells containing laminins and type IV collagens, which directly support epithelial and goblet cell adhesion differentiation and growth and, interstitial matrix secreted by fibroblasts in lamina propria, which provides mechanical and structural support. This review presents current knowledge on anatomy, composition of conjunctival ECM and related conjunctival disorders. Requirements of potential substrates for conjunctival tissue engineering and transplantation are discussed. Biological and synthetic substrates and their components are described in an accompanying review.