A comparison of keratoconus progression following collagen cross-linkage using standard or personalised keratometry thresholds.

OBJECTIVE: To define how estimates of keratoconus progression following collagen cross-linking (CXL) vary according to the parameter selected to measure corneal shape. MATERIALS AND METHODS: We estimated progression following CXL in 1677 eyes. We compared standard definitions of keratoconus progression based on published thresholds for Kmax, front K2, or back K2, or progression of any two of these three parameters, with the option of an increased threshold for Kmax values ≥ 55D. As corneal thickness reduces unpredictably after CXL, it was excluded from the principal analysis. We then repeated the analysis using novel adaptive estimates of progression for Kmax, front K2, or back K2, developed separately using 6463 paired readings from keratoconus eyes, with a variation of the Bland-Altman method to determine the 95% regression-based limits of agreement (LoA). We created Kaplan-Meier survival plots for both standard and adaptive thresholds. The primary outcome was progression five years after a baseline visit 9-15 months following CXL. RESULTS: Progression rates were 8% with a standard (≥ 1.5D) threshold for K2 or 6% with the static multi-parameter definition. With a ≥ 1D threshold for Kmax, the progression was significantly higher at 29%. With adaptive Kmax or K2, the progression rates were similar (20%) but less than with the adaptive multi-parameter method (22%). CONCLUSIONS: Estimates of keratoconus progression following CXL vary widely according to the reference criteria. Using adaptive thresholds (LoA) to define the repeatability of keratometry gives estimates for progression that are markedly higher than with the standard multi-parameter method.

Amniotic membrane transplantation for acute ocular burns.

BACKGROUND: Ocular surface burns can be caused by chemicals (alkalis and acids) or direct heat. One effect of the burn is damage to the limbal epithelial stem cells of the ocular surface with delayed re-epithelialisation, stem cell failure, and conjunctivalisation of the cornea. Amniotic membrane transplantation (AMT) performed in the acute phase (day 0 to day 7) following an ocular surface burn is claimed to reduce pain and accelerate healing. The surgery involves securing a layer of amniotic membrane (AM) to the eyelid margins as a patch to cover the entire ocular surface. However, there is debate about the severity of an ocular burn that may benefit from AMT and uncertainty of whether AMT improves outcomes. OBJECTIVES: To compare the effect of AMT with medical therapy in the first seven days after an ocular surface burn, compared to medical therapy alone. SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL; which contains the Cochrane Eyes and Vision Trials Register; 2021, Issue 9); Ovid MEDLINE; Ovid Embase; LILACS; the ISRCTN registry; ClinicalTrials.gov and the WHO ICTRP. We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 29 September 2021. SELECTION CRITERIA: We included randomised trials that compared an AMT applied in the first seven days following an ocular surface burn in addition to medical therapy with medical therapy alone. The outcome measures were failure of re-epithelialisation by day 21 post injury, visual acuity at final follow-up, corneal neovascularisation, symblepharon, time to re-epithelialisation and adverse effects. DATA COLLECTION AND ANALYSIS: Two review authors independently screened search results, assessed the included studies for risk of bias and extracted relevant data. We contacted trial investigators for missing information. We summarised data using risk ratios (RRs) and mean differences (MDs) as appropriate. MAIN RESULTS: We analysed two RCTs, but excluded individual patients who had been treated outside the acute phase in one of the studies (data provided by study authors). In total, 36 moderate burns from one RCT and 92 severe burns from two RCTs were evaluated separately. For both categories, the certainty of the evidence was downgraded principally as a result of high risks of performance and detection biases, and because of imprecision indicated by very wide confidence intervals. In addition, follow-up was insufficiently frequent to calculate time-to-epithelialisation precisely. Moderate severity ocular burns (Roper-Hall classification II-III) The relative risk of AMT on failure of epithelialisation by day 21 was 0.18 (0.02 to 1.31), and LogMAR visual acuity was 0.32 lower (0.55 to 0.09 lower) in the treatment group (i.e. better), suggesting a possible benefit of AMT. The GRADE assessment for failure of epithelialisation by day 21 was downgraded to very low due to the risk of bias and imprecision (very wide confidence intervals including no effect). The GRADE assessment for visual acuity at final follow-up was downgraded to low due to the risk of bias and imprecision (optimal information size not met). The relative effects of AMT on corneal neovascularisation (RR 0.56; 0.21 to 1.48), symblepharon (RR 0.41; 0.02 to 9.48) and time-to-epithelialisation (13 days lower; 26.30 lower to 0.30 higher) suggest possible benefit of AMT, but the wide confidence intervals indicate that both harm and benefit are possible. GRADE assessments for these outcomes were once again downgraded to very low due to the risk of bias and imprecision. Since adverse effects are rare, the small sample would have fewer occurrences of rare but potentially important adverse effects. The GRADE assessment for adverse effects was therefore considered to be low.  Severe ocular burns (Roper-Hall classification IV) The relative risk of AMT on failure of epithelialisation by day 21 was 1.03 (0.94 to 1.12), and LogMAR visual acuity was 0.01 higher (0.29 lower to 0.31 higher) in the treatment group (i.e, worse), indicating no benefit of AMT. GRADE assessments for failure of epithelialisation by day 21 and final outcomes were downgraded to low. The relative effects of AMT on corneal neovascularisation (RR 0.84; 0.66 to 1.06), symblepharon (RR 0.89; 0.56 to 1.42) and time-to-epithelialisation (1.66 days lower; 11.09 lower to 7.77 higher) may include both benefit and harm. GRADE assessments for corneal neovascularisation, symblepharon and time-to-epithelialisation were downgraded to low due to risk of bias and imprecision. For adverse effects, the GRADE assessment was downgraded to low, reflecting the small sample sizes in the RCTs. AUTHORS' CONCLUSIONS: There is uncertain evidence to support the treatment of moderate acute ocular surface burns with AMT in addition to standard medical therapy as a means of preventing failure of epithelialisation by day 21, improving visual outcome and reducing corneal neovascularisation, symblepharon formation and time-to-epithelialisation. For severe burns, the available evidence does not indicate any significant benefit of treatment with AMT.

Personalized Model to Predict Keratoconus Progression From Demographic, Topographic, and Genetic Data.

PURPOSE: To generate a prognostic model to predict keratoconus progression to corneal crosslinking (CXL). DESIGN: Retrospective cohort study. METHODS: We recruited 5025 patients (9341 eyes) with early keratoconus between January 2011 and November 2020. Genetic data from 926 patients were available. We investigated both keratometry or CXL as end points for progression and used the Royston-Parmar method on the proportional hazards scale to generate a prognostic model. We calculated hazard ratios (HRs) for each significant covariate, with explained variation and discrimination, and performed internal-external cross validation by geographic regions. RESULTS: After exclusions, model fitting comprised 8701 eyes, of which 3232 underwent CXL. For early keratoconus, CXL provided a more robust prognostic model than keratometric progression. The final model explained 33% of the variation in time to event: age HR (95% CI) 0.9 (0.90-0.91), maximum anterior keratometry 1.08 (1.07-1.09), and minimum corneal thickness 0.95 (0.93-0.96) as significant covariates. Single-nucleotide polymorphisms (SNPs) associated with keratoconus (n=28) did not significantly contribute to the model. The predicted time-to-event curves closely followed the observed curves during internal-external validation. Differences in discrimination between geographic regions was low, suggesting the model maintained its predictive ability. CONCLUSIONS: A prognostic model to predict keratoconus progression could aid patient empowerment, triage, and service provision. Age at presentation is the most significant predictor of progression risk. Candidate SNPs associated with keratoconus do not contribute to progression risk.

Posterior corneal vesicles are not associated with the genetic variants that cause posterior polymorphous corneal dystrophy.

PURPOSE: Posterior corneal vesicles (PCVs) have clinical features that are similar to posterior polymorphous corneal dystrophy (PPCD). To help determine whether there is a shared genetic basis, we screened 38 individuals with PCVs for changes in the three genes identified as causative for PPCD. METHODS: We prospectively recruited patients for this study. We examined all individuals clinically, with their first-degree relatives when available. We used a combination of Sanger and exome sequencing to screen regulatory regions of OVOL2 and GRHL2, and the entire ZEB1 coding sequence. RESULTS: The median age at examination was 37.5 years (range 4.7-84.0 years), 20 (53%) were male and in 19 (50%) the PCVs were unilateral. Most individuals were discharged to optometric review, but five had follow-up for a median of 12 years (range 5-13 years) with no evidence of progression. In cases with unilateral PCVs, there was statistically significant evidence that the change in the affected eye was associated with a lower endothelial cell density (p = 0.0003), greater central corneal thickness (p = 0.0277) and a steeper mean keratometry (p = 0.0034), but not with a higher keratometric astigmatism or a reduced LogMAR visual acuity. First-degree relatives of 13 individuals were available for examination, and in 3 (23%), PCVs were identified. No possibly pathogenic variants were identified in the PPCD-associated genes screened. CONCLUSION: We found no evidence that PCVs share the same genetic background as PPCD. In contrast to PPCD, we confirm that PCVs is a mild, non-progressive condition with no requirement for long-term review. However, subsequent cataract surgery can lead to corneal oedema.

Novel disease-causing variants and phenotypic features of X-linked megalocornea.

PURPOSE: The aim of the study was to describe the phenotype and molecular genetic causes of X-linked megalocornea (MGC1). We recruited four British, one New Zealand, one Vietnamese and four Czech families. METHODS: All probands and three female carriers underwent ocular examination and Sanger sequencing of the CHRDL1 gene. Two of the probands also had magnetic resonance imaging (MRI) of the brain. RESULTS: We identified nine pathogenic or likely pathogenic and one variant of uncertain significance in CHRDL1, of which eight are novel. Three probands had ocular findings that have not previously been associated with MGC1, namely pigmentary glaucoma, unilateral posterior corneal vesicles, unilateral keratoconus and unilateral Fuchs heterochromic iridocyclitis. The corneal diameters of the three heterozygous carriers were normal, but two had abnormally thin corneas, and one of these was also diagnosed with unilateral keratoconus. Brain MRI identified arachnoid cysts in both probands, one also had a neuroepithelial cyst, while the second had a midsagittal neurodevelopmental abnormality (cavum septum pellucidum et vergae). CONCLUSION: The study expands the spectrum of pathogenic variants and the ocular and brain abnormalities that have been identified in individuals with MGC1. Reduced corneal thickness may represent a mild phenotypic feature in some heterozygous female carriers of CHRDL1 pathogenic variants.

Effect of Corneal Cross-linking versus Standard Care on Keratoconus Progression in Young Patients: The KERALINK Randomized Controlled Trial.

PURPOSE: To examine the efficacy and safety of corneal cross-linking (CXL) for stabilization of progressive keratoconus. DESIGN: Observer-masked, randomized, controlled, parallel-group superiority trial. PARTICIPANTS: Sixty participants 10 to 16 years of age with progressive keratoconus, one eye of each deemed the study eye. METHODS: The study eye was randomized to either CXL plus standard care or standard care alone, with spectacle or contact lens correction as necessary for vision. MAIN OUTCOME MEASURES: The primary outcome was steep keratometry (K2) in the study eye as a measure of the steepness of the cornea at 18 months. Secondary outcomes included keratoconus progression defined as a 1.5-diopter (D) increase in K2, visual acuity, keratoconus apex corneal thickness, and quality of life. RESULTS: Of 60 participants, 30 were randomized to CXL and standard care groups. Of these, 30 patients in the CXL group and 28 patients in the standard care group were analyzed. Mean K2 in the study eye 18 months after randomization was 49.7 D (standard deviation [SD], 3.8 D) in the CXL group and 53.4 D (SD, 5.8 D) in the standard care group. The adjusted mean difference in K2 in the study eye was -3.0 D (95% confidence interval [CI], -4.9 to -1.1 D; P = 0.002), favoring CXL. Adjusted differences between groups in uncorrected and corrected vision favored eyes receiving CXL: -0.31 logarithm of the minimum angle of resolution (logMAR; 95% CI, -0.50 to -0.11 logMAR; P = 0.002) and -0.51 logMAR (95% CI, -1.37 to 0.35 logMAR; P = 0.002). Keratoconus progression in the study eye occurred in 2 patients (7%) randomized to CXL compared with 12 patients (43%) randomized to standard care. The unadjusted odds ratio suggests that on average, patients in the CXL arm had 90% (odds ratio, 0.1; 95% CI, 0.02-0.48; P = 0.004) lower odds of experiencing progression compared with those receiving standard care. CONCLUSIONS: CXL arrests progression of keratoconus in the majority of young patients. CXL should be considered as a first-line treatment in progressive disease. If the arrest of keratoconus progression induced by CXL is sustained in longer follow-up, particular benefit may be derived from avoiding a later requirement for contact lens wear or corneal transplantation.

Graft Survival After Penetrating and Endothelial Keratoplasty in Iridocorneal Endothelial Syndrome.

PURPOSE: To compare the survival of a first penetrating keratoplasty (PK) or endothelial keratoplasty (EK) for iridocorneal endothelial (ICE) syndrome with transplant survival in Fuchs endothelial dystrophy (FED) and pseudophakic bullous keratopathy (PBK). METHODS: We compared graft survival of PK and EK for ICE syndrome for 2 time periods. We then compared graft survival in ICE syndrome with graft survival in FED and PBK. Kaplan-Meier estimates of graft survival up to 5 years posttransplant were calculated with 95% confidence intervals (CI), whereas comparisons between the groups were performed using the log-rank test. RESULTS: We included 86 first transplants for ICE syndrome. There was no difference in graft survival between the 58 PKs and the 28 EKs for up to 5 years after surgery (P = 0.717). For the period from 2009 to 2017, the 5-year graft survival rates for ICE syndrome were 64.3% (CI, 21.8%-88.0%) for the 16 PKs and 66.8% (CI, 41.8%-83.0%) for the 26 EKs (P = 0.469). Between 2009 and 2017, the 5-year survival rate for 42 grafts with ICE syndrome was 62.7% (CI, 39.6%-79.0%), which was lower than 75.9% (CI, 74.2%-77.4%) in 7058 transplants for FED but higher than 55.1% (CI, 52.0%-58.0%) in 3320 transplants for PBK, although the numbers of ICE transplants are too small to tell whether this difference was by chance. CONCLUSIONS: The results indicate no difference in graft survival between PK and EK for ICE syndrome. Graft survival in ICE syndrome is intermediate between that of FED and PBK.

Differential effects of primary disease and corneal vascularisation on corneal transplant rejection and survival.

AIMS: To investigate the relative risk of pretransplant corneal vascularisation on rate of rejection and graft failure within 5 years of surgery when categorised by indication for transplantation.We analysed all adults recorded in the UK transplant registry who had a first cornea transplant for keratoconus (KC), pseudophakic bullous keratopathy (PBK) or previous infection (viral/bacterial/fungal/protozoan) between 1999 and 2017. We analysed the number of quadrants of the recipient cornea vascularised before transplant and type of vascularisation, the interval post-transplant to rejection, if any, and the outcome at 5 years post-transplant. Risk factors for rejection and transplant failure were modelled by multivariable risk-adjusted Cox regression. RESULTS: Corneal vascularisation was recorded in 10%, 25% and 67% of patients with KC, PBK and infection, respectively. Individuals with PBK had an increased hazard of transplant rejection only when there were more than two quadrants of vascularisation (HR 1.5, p=0.004) when either superficial and/or deep vascularisation was present (HR 1.3 and 1.4, respectively, p=0.004). Individuals who had a transplant for previous infection had an increased hazard of rejection with four quadrants of vascularisation (HR 1.6, p=0.003). There was no risk-adjusted increase in transplant failure associated with vascularisation in any group. There was weak evidence of reduction in risk of rejection and/or failure associated with lamellar compared with penetrating transplantation in KC and PBK in vascularised recipient corneas. CONCLUSION: Vascularisation is a risk factor for corneal allograft rejection within 5 years. The indication for transplantation has a clinically significant effect on the magnitude of this risk.

Serious corneal complications and undiagnosed floppy eyelid syndrome; A case series and a 10-year retrospective review.

PURPOSE: To describe three individuals with severe keratitis and a substantial delay before floppy associated eyelid syndrome (FES) was identified, and to estimate the prevalence of severe corneal disease in individuals with FES. METHODS: We defined severe keratitis as corneal ulceration, vascularization or scar that affected vision. We recorded the clinical characteristics, the duration of symptoms before the diagnosis of FES, subsequent management and outcome. Then, to determine the proportion of individuals with FES who had severe corneal disease, we interrogated the Moorfields Eye Hospital electronic patient record (EPR) for the diagnosis of FES made in the ten-year interval from 2008. RESULTS: Three individuals presented with severe progressive keratitis (median duration of symptoms 19 months, range 2-48 months). All were male and with a high body mass index (BMI, range 38.9-41.2). In each the etiology of the keratitis was unclear before FES was identified. All had very lax lids and were aware they had periods of lid malposition during sleep. None mentioned symptoms of obstructive sleep apnoea (OSA) until they or their partner were directly questioned. The management of keratitis included both medical and surgical corneal treatments, with tarsorrhaphy and lid shortening surgery. We identified an additional 104 cases of FES from the EPR, of which 4 (3.8%) had severe keratitis. CONCLUSIONS: FES can be missed unless signs of lid laxity are directly elicited. A delay in diagnosis can result in clinical deterioration, with unnecessary investigations and treatments. An assessment for FES should be included as part of the evaluation of individuals with severe or chronic keratitis.

Genetic Variants Associated With Corneal Biomechanical Properties and Potentially Conferring Susceptibility to Keratoconus in a Genome-Wide Association Study.

IMPORTANCE: Keratoconus is an important cause of visual loss in young adults, but little is known about its genetic causes. Understanding the genetic determinants of corneal biomechanical factors may in turn teach us about keratoconus etiology. OBJECTIVES: To identify genetic associations with corneal biomechanical properties and to examine whether these genetic variants are associated with keratoconus. DESIGN, SETTING, AND PARTICIPANTS: A stage 1 discovery and replication genome-wide association study (GWAS) of corneal biomechanical properties was performed in 2 cross-sectional populations (6645 participants from the European Prospective Investigation into Cancer and Nutrition [EPIC]-Norfolk Eye Study and 2384 participants from the TwinsUK study). In stage 2, the association of genetic determinants identified in stage 1 with keratoconus was examined in a case-control study. A total of 752 patients with keratoconus were compared with 974 TwinsUK participants (undergoing direct sequencing) or 13 828 EPIC-Norfolk participants (undergoing genotyping and imputation) who were not part of the stage 1 analysis. Data were collected from March 1, 1993, through March 13, 2017, and analyzed from November 1, 2015, through February 1, 2018. EXPOSURES: In stage 1, allele dosage at genome-wide single-nucleotide polymorphisms (SNPs); in stage 2, allele dosage at SNPs with genome-wide significance (P < 5 × 10-8) in stage 1 and not previously reported as associated with corneal disease. MAIN OUTCOMES AND MEASURES: In stage 1, corneal hysteresis (CH) and corneal resistance factor (CRF), measured with the Ocular Response Analyzer (ORA); in stage 2, association with keratoconus compared with controls. RESULTS: Among 6645 participants in the discovery cohort (3635 women (54.7%); mean age, 69 years [range, 48-92 years]), 7 genome-wide significant loci associated with CH or CRF were identified that were independently replicated. Two further suggestive loci were identified after meta-analysis. To date, 5 of the identified loci, at ANAPC1, ADAMTS8, ADAMTS17, ABCA6, and COL6A1, have not previously been reported as associated with corneal disease. The ABCA6 locus (rs77542162) was associated with keratoconus using the TwinsUK (odds ratio [OR], 0.50; 95% CI, 0.27-0.92; P = .03) and EPIC-Norfolk controls (OR, 0.39; 95% CI, 0.22-0.70; P = .002). The other loci were associated with keratoconus using TwinsUK (OR per effect allele for ADAMTS8, 0.51 [95% CI, 0.37-0.71; P = 7.9 × 10-5]; for COL6A1, 1.65 [95% CI, 1.05-2.59; P = .03]) or EPIC-Norfolk (OR per effect allele for ANAPC1, 0.78 [95% CI, 0.68-0.89; P = 3.7 × 10-4]; for ADAMTS17, 0.82 [95% CI, 0.68-0.99; P = .04]) controls. CONCLUSIONS AND RELEVANCE: Five loci that are associated with corneal biomechanical properties and that have suggestive associations with keratoconus were reported. These findings suggest the role of type VI collagen, extracellular matrix, and connective-tissue development for corneal biomechanics and keratoconus and the role of CH and CRF as biomarkers for keratoconus.

Paraproteinemic keratopathy associated with monoclonal gammopathy of undetermined significance (MGUS): clinical findings in twelve patients including recurrence after keratoplasty.

PURPOSE: To describe the ocular findings of 12 subjects with paraproteinemic keratopathy associated with monoclonal gammopathy of undetermined significance (MGUS). METHODS: Ocular examination included corneal spectral domain optical coherence tomography. In three individuals with an initial diagnosis of a lattice or Thiel-Behnke corneal dystrophy, the TGFBI gene was screened by conventional Sanger sequencing. RESULTS: We confirmed a diagnosis of MGUS by systemic examination and serum protein electrophoresis in 12 individuals (9 males and 3 females), with a mean age at presentation of 52.2 years (range 24-63 years) and mean follow-up 6.4 years (range 0-17 years). The best-corrected visual acuity (BCVA) at presentation ranged from 1.25 to 0.32. In all individuals, the corneal opacities were bilateral. The appearances were diverse and included superficial reticular opacities and nummular lesions, diffuse posterior stromal opacity, stromal lattice lines, superficial and stromal crystalline deposits, superficial haze and a superficial ring of hypertrophic tissue. In one individual, with opacities first recorded at 24 years of age, we documented the progression of corneal disease over the subsequent 17 years. In another individual, despite systemic treatment for MGUS, recurrence of deposits was noted following bilateral penetrating keratoplasties. The three individuals initially diagnosed with inherited corneal dystrophy were negative for TGFBI mutations by direct sequencing. CONCLUSION: A diagnosis of MGUS should be considered in patients with bilateral corneal opacities. The appearance can mimic corneal dystrophies or cystinosis. In our experience, systemic treatment of MGUS did not prevent recurrence of paraproteinemic keratopathy following keratoplasty.

Cytomegalovirus infection is not a major cause of corneal graft failure in the United Kingdom.

BACKGROUND: Cytomegalovirus (CMV) endotheliitis is a significant cause for acute corneal allograft rejection in East Asian populations, where there is a high CMV seroprevalence. To determine how frequently CMV is associated with corneal graft failure in the UK, we looked for the presence of CMV DNA in grafts that had failed and had been removed at repeat keratoplasty. We also looked for CMV DNA in corneal rims discarded after corneal transplantation. METHODS: In this retrospective study, we identified 54 cases of corneal graft failure following endothelial rejection and 38 control grafts that had failed without a history of endothelial rejection. For these groups archived formalin-fixed paraffin-embedded (FFPE) tissue samples were retrieved. We also prospectively examined 80 non-fixed cornea rims following transplantation surgery. In all samples nested quantitative PCR was used to identify CMV, herpes simplex virus (HSV) and varicella zoster virus (VZV) DNA. We also used in situ hybridisation to examine for CMV DNA in the FFPE samples. RESULTS: No CMV or VZV DNA was detected in any of the archived case or control FFPE tissues. One corneal rim from the control group was positive for HSV. In situ hybridisation for CMV was negative for CMV in all FFPE samples. No CMV, VZV or HSV DNA was detected in the donor corneal rim samples. CONCLUSION: CMV DNA was not identified in excised failed corneal tissue or from tissue prior to transplantation. We infer that CMV infection is not a significant factor risk for corneal graft failure in the United Kingdom.

Iatrogenic limbal stem cell deficiency following drainage surgery for glaucoma.

OBJECTIVE: To describe conjunctival epithelial overgrowth of the cornea after surgery for glaucoma. METHODS: This is a retrospective case series (setting: Moorfields Eye Hospital). Fourteen eyes of 13 patients with suspected limbal stem cell deficiency (LSCD) and corneal conjunctivalization after glaucoma drainage surgery. Conjunctivalization was defined as corneal epithelium that demonstrated late stain after topical application of fluorescein. Patient demographics, clinical features, potential risk factors, treatment, and final visual acuity were recorded. Main outcome measures were potential risk factors for conjunctivalization, complications, and response to treatment. RESULTS: Eleven eyes had multiple procedures involving the limbus, and in 11 eyes mitomycin C (MMC) or 5 fluorouracil had been used as an adjunct to reduce fibrosis. Affected eyes typically had a segment of late stain with fluorescein based at the site of previous glaucoma surgery, but in one eye there was total loss of the corneal epithelial phenotype. All eyes previously had topical treatment for their glaucoma but only 2 had an ocular surface disease associated with LSCD. Most cases were asymptomatic, but in 3 eyes there was visual loss when the abnormal phenotype crossed the visual axis. In these 3 eyes there was recurrent epithelial breakdown, often at the interface between the 2 epithelial phenotypes. In one individual, these symptoms resolved after limbal epithelial transfer from the unaffected contralateral eye. CONCLUSIONS: Glaucoma drainage surgery can damage the adjacent corneal limbal epithelial stem cell population. This can be associated with recurrent epithelial breakdown and reduced vision. If there is visual loss, limbal epithelial transplantation is a potential treatment option.

Use of an onlay corneal lamellar graft for brittle cornea syndrome.

Brittle cornea syndrome (BCS1 OMIM #229200, BCS2 #614170) is a rare autosomal recessive condition characterised by diffuse thinning and fragility of the cornea. Affected individuals are at risk of globe rupture and blindness after relatively minor eye trauma. We describe a 9-year-old girl with BCS1, already blind in one eye following trauma, who had a 14 mm diameter corneoscleral onlay graft to her contralateral eye to reduce gross irregular corneal astigmatism and potentially to reduce further risk from accidental injury. Although there was a significant initial improvement in the unaided visual acuity, there was subsequent visual loss from secondary glaucoma. In addition, despite the onlay graft, an acute corneal hydrops developed approximately 2 years following surgery, suggesting that in BCS1, corneal tissue degeneration or resorption continues despite external support. Finally, because secondary glaucoma is not a feature of BCS1, we speculate that the onlay graft may have reduced aqueous outflow by compression of the thinned sclera.

Acute Glaucoma Following Cyanoacrylate Glue Patch for Corneal Perforation.

PURPOSE: To describe a case of acute glaucoma after cyanoacrylate gluing for a nontraumatic central corneal perforation. METHODS: A 55-year-old woman with history of rheumatoid arthritis and severe dry eye presented to emergency with a right central corneal perforation. She was treated successfully with the use cyanoacrylate glue patch but iridocorneal adhesions remained. The next day she presented with ocular pain, headaches, and vomiting. On examination she had shallow anterior chamber (AC) with no aqueous leakage but her intraocular pressure (IOP) was 56 mm Hg measured with rebound tonometry. An anterior segment optical coherence tomography scan showed a 360 degrees central iris adhesion with shallow AC. Topical and oral treatment for acute glaucoma was given that decreased her IOP. She then underwent urgent surgery to release the iridocorneal adhesions and restore aqueous flow that was achieved without replacing the glue patch. RESULTS: One day postoperatively her right eye was comfortable and her IOP measurement remained within normal limits. The AC was deep with no iridocorneal adhesions. CONCLUSIONS: Close monitoring of the IOP is recommendable in central corneal perforations with iris adhesions managed with cyanoacrylate glue due to the potential developing of aqueous blockage.

Mutations in CPAMD8 Cause a Unique Form of Autosomal-Recessive Anterior Segment Dysgenesis.

Anterior segment dysgeneses (ASDs) comprise a spectrum of developmental disorders affecting the anterior segment of the eye. Here, we describe three unrelated families affected by a previously unclassified form of ASD. Shared ocular manifestations include bilateral iris hypoplasia, ectopia lentis, corectopia, ectropion uveae, and cataracts. Whole-exome sequencing and targeted Sanger sequencing identified mutations in CPAMD8 (C3 and PZP-like alpha-2-macroglobulin domain-containing protein 8) as the cause of recessive ASD in all three families. A homozygous missense mutation in the evolutionarily conserved alpha-2-macroglobulin (A2M) domain of CPAMD8, c.4351T>C (p. Ser1451Pro), was identified in family 1. In family 2, compound heterozygous frameshift, c.2352_2353insC (p.Arg785Glnfs∗23), and splice-site, c.4549-1G>A, mutations were identified. Two affected siblings in the third family were compound heterozygous for splice-site mutations c.700+1G>T and c.4002+1G>A. CPAMD8 splice-site mutations caused aberrant pre-mRNA splicing in vivo or in vitro. Intriguingly, our phylogenetic analysis revealed rodent lineage-specific CPAMD8 deletion, precluding a developmental expression study in mice. We therefore investigated the spatiotemporal expression of CPAMD8 in the developing human eye. RT-PCR and in situ hybridization revealed CPAMD8 expression in the lens, iris, cornea, and retina early in development, including strong expression in the distal tips of the retinal neuroepithelium that form the iris and ciliary body, thus correlating CPAMD8 expression with the affected tissues. Our study delineates a unique form of recessive ASD and defines a role for CPAMD8, a protein of unknown function, in anterior segment development, implying another pathway for the pathogenicity of ASD.

Spectrum of Clinical Signs and Genetic Characterization of Gelatinous Drop-Like Corneal Dystrophy in a Colombian Family.

PURPOSE: To describe the clinical signs of gelatinous drop-like corneal dystrophy (GDLD) in a consanguineous Colombian family and determine the underlying genetic cause. METHODS: We performed ocular examination of available family members and bidirectionally Sanger sequenced the GDLD-associated gene, TACSTD2. In one individual, the presence of subepithelial amyloid was confirmed with biopsy. RESULTS: The parents were consanguineous and 5 of their 10 children had GDLD. Typical mulberry subepithelial deposits with subepithelial vascularization were present in 3 individuals; 2 individuals only had mild polymorphic anterior stromal opacity. We identified a homozygous TACSTD2 missense mutation, c.551A>G, p.(Tyr184Cys), in the affected family members. Both parents were heterozygous for the mutation, and unaffected siblings were either heterozygous or homozygous wild-type for this allele. In the Colombian population, this mutation has a minor allele frequency of 0.53%. CONCLUSION: The clinical presentation of GDLD in this family was variable and does not solely support an age-dependent progression of the phenotype, suggesting that environmental or other genetic factors can modify phenotypic expression. The relatively high prevalence of this mutation in the Colombian population suggests that other individuals may have undiagnosed subclinical disease.

Pharmacokinetics of Meropenem for Use in Bacterial Keratitis.

PURPOSE: To investigate the toxicity and corneal pharmacokinetics of meropenem as a potential antimicrobial for bacterial keratitis. METHODS: Corneal epithelial cell and keratocyte toxicity was investigated using methyl thiazolyl tetrazolium (MTT) and LIVE/DEAD assays. The penetration of meropenem through the human cornea was measured using an artificial anterior chamber. In one group of corneas, the epithelial and endothelial layers were removed and in a second group these layers were left intact. We applied 50 µL (10 mg/mL) meropenem to the corneal surface and collected samples in the anterior chamber from 45 minutes up to 24 hours. Meropenem concentrations were estimated with a bioassay and HPLC. RESULTS: Meropenem had significantly higher cellular metabolic activity (MTT assay) at both 5 mg/mL and 2.5 mg/mL compared with moxifloxacin (P = 0.029 and P = 0.018, respectively), with 96% cell viability (LIVE/DEAD assay). The measured values for meropenem concentrations in corneal and aqueous samples were significantly higher using a bioassay than with HPLC (P = 0.004). For both intact and denuded corneas, the concentrations in the anterior chamber increased from 0.48 µg/mL (SD 0.89) and 0.89 µg/mL (SD 0.81) to 6.35 µg/mL (SD 0.81) and 13.48 µg/mL (SD 14.82) using HPLC, and from 0.68 µg/mL (SD 1.50) and 1.31 µg/mL (SD 1.55) to 47.03 µg/mL (SD 5.51) and 43.69 µg/mL (SD 27.22) measured with a bioassay. CONCLUSIONS: Meropenem has very low toxicity in vitro. It has good corneal penetration, achieving anterior chamber concentrations above MIC90 for bacteria such as Staphylococcus aureus, Pseudomonas aeruginosa, streptococci, coagulase-negative staphylococci, and the Enterobacteriaceae.

Identification of six novel mutations in ZEB1 and description of the associated phenotypes in patients with posterior polymorphous corneal dystrophy 3.

Posterior polymorphous corneal dystrophy 3 (PPCD3) is a rare autosomal dominant disorder caused by mutations in ZEB1. To date all identified disease-causing variants were unique to the studied families, except for c.1576dup. We have detected six novel ZEB1 mutations; c.1749_1750del; p.(Pro584*) and c.1717_1718del; p.(Val573Phefs*12) in two Czech families, c.1176dup; p.(Ala393Serfs*19), c.1100C>A; p.(Ser367*), c.627del; p.(Phe209Leufs*11) in three British families and a splice site mutation, c.685-2A>G, in a patient of Sri Lankan origin. An additional British proband had the c.1576dup; p.(Val526Glyfs*3) mutation previously reported in other populations. Clinical findings were variable and included bilateral congenital corneal opacity in one proband, development of opacity before the age of 2 years in another individual and bilateral iris flocculi in yet another subject. The majority of eyes examined by corneal topography (10 out of 16) had an abnormally steep cornea (flat keratometry 46.5-52.7 diopters, steep keratometry 48.1-54.0 diopters). One proband underwent surgery for cryptorchidism. Our study further demonstrates that PPCD3 can present as corneal edema in early childhood, and that an abnormally steep keratometry is a common feature of this condition. As cryptorchidism has been previously observed in two other PPCD3 cases, its association with the disease warrants further investigation.

Localisation of epithelial cells capable of holoclone formation in vitro and direct interaction with stromal cells in the native human limbal crypt.

Limbal epithelial stem cells (LESCs) are essential to maintain the transparent ocular surface required for vision. Despite great advances in our understanding of ocular stem cell biology over the last decade, the exact location of the LESC niche remains unclear. In the present study we have used in vitro clonal analysis to confirm that limbal crypts provide a niche for the resident LESCs. We have used high-resolution imaging of the basal epithelial layer at the limbus to identify cells with a morphology consistent with stem cells that were only present within the basal layer of the limbal crypts. These cells are proximal to limbal stromal cells suggesting direct cell-to-cell interaction. Serial block-face scanning electron microscopy (SBFSEM) confirmed that the putative LESCs are indeed in direct contact with cells in the underlying stroma, a contact that is facilitated by focal basement membrane interruptions. Limbal mesenchymal cells previously identified in the human limbus collocate in the crypt-rich limbal stromal area in the vicinity of LESCs and may be involved in the cell-to-cell contact revealed by SBFSEM. We also observed a high population of melanocytes within the basal layer of the limbal crypts. From these observations we present a three dimensional reconstruction of the LESC niche in which the stem cell is closely associated and maintained by both dendritic pigmented limbal melanocytes and elongated limbal stromal cells.