Analysis of microbial keratitis incidence, isolates and in-vitro antimicrobial susceptibility in the East of England: a 6-year study.

BACKGROUND/OBJECTIVES: To report the incidence, microbiological profile and in-vitro antimicrobial susceptibilities of microbial keratitis (MK) in the East of England (EoE) over a 6-year period. SUBJECTS/METHODS: A retrospective study of patients diagnosed with MK who underwent corneal scraping at participating trusts, within the EoE, between 01/01/2015-01/07/2020. Analysis was performed on MK isolate profiles, in-vitro anti-microbial sensitivities and trends over time. RESULTS: The mean incidence of IK, in the EoE, was estimated at 6.96 per 100 000 population/year. 1071 corneal scrapes were analysed, 460 were culture positive (42.95%) of which 87.2% were bacteria (50.3% gram-positive and 49.7% gram-negative), 2.4% polymicrobial, 9.3% fungi and 1.1% acanthamoeba. The most common organisms were pseudomonas spp (29.57%). There was a non-statistically significant trend (NST) in increasing incidence of pseudomonas spp, staph aureus and serratia (p = 0.719, p = 0.615, and p = 0.099 respectively) and a declining NST in Fungi (p = 0.058). Susceptibilities in-vitro to, penicillin classes, fluoroquinolone and aminoglycosides were 76.7% and 89.4%, 79.2% and 97.2% and 95.4 and 96.1% to gram-positive and gram-negative bacteria respectively. Gram-negative organisms were increasingly resistant to cephalosporins with a 19.2% reduction in sensitivity over time. (p = 0.011). Ceftriaxone showed the greatest decrease in sensitivity of 41.67% (p = 0.006). CONCLUSION: In the EoE, MK is relatively prevalent though likely underestimated. Profiles are similar to other UK regions with the exception of a higher fungal and lower acanthamoeba incidence. Common first and second-line antimicrobial selection provides, on the whole, good coverage. Nevertheless, anti-microbial resistance, to cephalosporins, was observed so selection should be carefully considered when treating MK empirically.

A Randomized Controlled Trial Comparing Microthin Descemet Stripping Automated Endothelial Keratoplasty With Descemet Membrane Endothelial Keratoplasty: Two-Year Report.

PURPOSE: The purpose of this study was to report the 2-year outcomes of a double-blinded randomized controlled trial comparing Descemet membrane endothelial keratoplasty (DMEK) and microthin Descemet stripping automated endothelial keratoplasty (MT-DSAEK). METHODS: Fifty-six eyes of 56 patients were randomized to DMEK or microthin DSAEK (MT-DSAEK). The main outcome measure was best spectacle-corrected visual acuity (BSCVA) at 24 months. Other secondary outcomes included complications, endothelial cell density, and vision-related quality-of-life (vQoL) scores. RESULTS: There was no statistically significant difference in BSCVA between the DMEK and MT-DSAEK groups at the 2-year time point (mean ± SD; 0.04 ± 0.14 vs. 0.12± 0.19, P = 0.061) in contrast to the 1-year results (mean ± SD; 0.04 ± 0.13 vs. 0.11 ± 0.09, P = 0.002) previously reported. Endothelial cell density did not show a statistically significant difference at 24 months between the DMEK and MT-DSAEK groups (1522 ± 293 cell/mm2 vs. 1432 ± 327 cells/mm2, P = 0.27). There were 2 additional graft rejection episodes in the MT-DSAEK group between the 1- and 2-year follow-up periods, but this did not result in graft failure. The mean vQoL scores between DMEK and MT-DSAEK indicated similar patient satisfaction between the groups (97.1 ± 4.0 vs. 92.6 ± 10.2, P = 0.13). CONCLUSIONS: In summary, the trial showed no significant difference in BSCVA at 24 months between the DMEK and MT-DSAEK groups. Both techniques continued to demonstrate comparable outcomes for complication rates, endothelial cell loss, and patient-reported vQoL scores. TRIAL REGISTRATION: ISRCTN10578843.

Maternal finger-prick allogenic blood for persistent corneal epithelial defects.

This is a case of a 17-year-old patient with aniridia-related keratopathy and persistent epithelial defect (PED) treated successfully using maternal finger-prick blood (FPB). Maternal allogenic FPB treatment was initiated to the patient who was non-compliant with the use of autologous FPB. The PED was successfully managed with maternal FPB treatment with rapid and complete closure of the epithelial defect. Additionally, there was immediate and sustained symptomatic improvement to pain and recovery of vision in the only seeing eye. There was no immunological reaction to allogenic blood. Maternal finger-prick allogenic blood could serve as a potential alternative to serum eye drops or autologous FPB in the management of refractory PED, particularly in reference to the paediatric or the vulnerable age group. Further studies are required to confirm the role of allogenic blood in the treatment of PED.

Microthin Descemet Stripping Automated Endothelial Keratoplasty Versus Descemet Membrane Endothelial Keratoplasty: A Randomized Clinical Trial.

PURPOSE: To compare visual outcomes, complications, and vision-related quality of life (QoL) after microthin Descemet stripping automated endothelial keratoplasty (MT-DSAEK) versus Descemet membrane endothelial keratoplasty (DMEK) for the management of corneal endothelial dysfunction in Fuchs dystrophy. METHODS: This is a prospective, double-blinded randomized controlled clinical trial. Patients with visually significant endothelial decompensation from Fuchs dystrophy were prospectively randomized to receive MT-DSAEK or DMEK surgery. The primary outcome was best spectacle-corrected visual acuity (BSCVA) at 12 months. Secondary outcomes included refraction, keratometry, endothelial cell count, complications, and vision-related QoL at 6 and 12 months postoperatively. RESULTS: A total of 56 eyes of 56 patients were enrolled, 28 in each group. Postoperatively, LogMAR mean BSCVA in the MT-DSAEK group was 0.17 ± 0.08 and 0.11 ± 0.09 at 6 and 12 months compared with 0.09 ± 0.13 and 0.04 ± 0.13 after DMEK (P = 0.03, P = 0.002 respectively) with the DMEK cohort achieving 3.5 logarithm of the minimum angle of resolution letters better BSCVA at 1 year compared with MT-DSAEK. Complication rates were similar with 3.5% rebubbling rate in both groups, 1 primary graft failure in DMEK and a single endothelial rejection in the MT-DSAEK arm. Vision-related QoL was comparable at 6 and 12 months postoperatively, and no eyes demonstrated loss of vision from preoperative BSCVA. CONCLUSIONS: DMEK surgery resulted in significantly better BSCVA at 1, 3, 6, and 12 months postoperatively compared with MT-DSAEK. Patient satisfaction was similar with no differences reported in vision-related QoL scores, as was the complications profile between groups. Thus, our results favor DMEK as the better choice procedure for eyes with Fuchs-related corneal decompensation without ocular comorbidities.

Feasibility Study of Human Corneal Endothelial Cell Transplantation Using an In Vitro Human Corneal Model.

PURPOSE: To test the feasibility of a cell therapy approach to treat corneal endothelial (CE) disorders using an in vitro model of human corneal decompensation. METHODS: A CE decompensation model was established by removal of the Descemet membrane/endothelium complex from cadaveric human corneas in an air interface organ culture system (group 2) and compared with normal corneas (group 1). The posterior stroma of decompensated corneas was seeded with immortalized human corneal endothelial cells (HCEC-12) in group 3 and passage 0 primary human CE cells in group 4 corneas. Functional effects on stromal thickness were determined with histological analysis 3 to 10 days after cell therapy treatment. RESULTS: Removal of the Descemet membrane/endothelium complex in group 2 corneas resulted in a stromal thickness of 903 ± 86 µm at 12 hours compared with 557 ± 72 µm in group 1 corneas. Stromal thickness reduced from 1218 ± 153 µm to 458 ± 90 µm (63% ± 6%, P = 0.001) after cell transplantation in group 3 and from 1100 ± 86 µm to 489 ± 94 µm (55% ± 7%, P = 0.00004) in group 4. Posttransplantation histology demonstrated formation of a monolayer of corneal endothelium attached to the posterior stromal surface. CONCLUSIONS: Direct transplantation of cultured human CE cells and immortalized HCEC-12 to bare posterior corneal stroma resulted in formation of an endothelial monolayer and restoration of stromal hydration to physiological thickness, demonstrating the feasibility of cell therapy in treatment of CE decompensation in a human in vitro model.

Quality indicators in a community optometrist led cataract shared care scheme.

PURPOSE: Cataract shared care schemes involving community optometrists show wide variation in practice. We report on defined key performance indicators (KPIs) which improve accountability between stakeholders. METHODS: In this prospective study over nine months at a UK public hospital, we evaluated the outcomes of consecutive direct cataract referrals from community optometrists against two KPIs agreed under a service-level agreement between the Hospital Eye Service and community optometrists: (1) 85% of patients listed for cataract listing at first consultation; and (2) 90% postoperative feedback return rate on patients discharged to community optometrists. A detailed analysis on referral triage, surgical listing and postoperative form return rate is reported in this study. RESULTS: A total of 733 direct cataract referrals were received using a designated referral form of which 86% were listed for cataract surgery. The predominant reason for not listing was a failure to reach the visual threshold set by the local clinical commissioning guidelines. Out of 569 cataract surgical episodes, 402 (71%) patients were discharged on the same day of surgery to community optometrist follow up. Completed postoperative feedback was returned from 374 patients (93%). CONCLUSION: Direct cataract referrals from accredited community optometrists led to a majority of patients receiving a definitive clinical decision during first consultation. Postoperative community follow up reduced hospital visits and allowed for convenient consultation closer to home following uncomplicated cataract surgery. A service-level agreement with an accreditation scheme measured against KPIs enhances the accountability of stakeholders involved in the cataract shared care scheme.

Effect of vital dyes on human corneal endothelium and elasticity of Descemet's membrane.

The purpose of this study was to evaluate the effects of vital dyes on human Descemet's membranes (DMs) and endothelia. DMs of 25 human cadaveric corneas with research consent were treated with dyes routinely used in Descemet membrane endothelial keratoplasty (DMEK), 0.05% Trypan blue (TB) or a combination of 0.15% Trypan blue, 0.025% Brilliant blue and 4% Polyethylene glycol (commercial name Membrane Blue Dual; MB). The effects of these two dyes on (i) endothelial cell viability, (ii) DM mechanical properties as assessed by atomic force microscopy, and iii) qualitative DM dye retention were tested for two varying exposure times (one or four minutes). No significant differences in cell toxicity were observed between treatments with TB and MB at the two different exposure times (P = 0.21). Further, both dyes led to a significant increase in DM stiffness: exposure to TB and MB for one minute increased the apparent elastic modulus of the DM by 11.2% (P = 8*10-3) and 17.7%, respectively (P = 4*10-6). A four-minute exposure led to an increase of 8.6% for TB (P = 0.004) and 13.6% for MB (P = 0.03). Finally, at 25 minutes, the dye retention of the DM was considerably better for MB compared to TB. Taken together, a one-minute exposure to MB was found to improve DM visibility compared to TB, with a significant increase in DM stiffness and without detrimental effects on endothelial cell viability. The use of MB could therefore improve (i) visibility of the DM scroll, and (ii) intraoperative unfolding, enhancing the probability of successful DMEK surgery.

Identification of Prdm genes in human corneal endothelium.

Corneal endothelial cells (CECs) are essential for maintaining corneal stromal hydration and ensuring its transparency, which is necessary for normal vision. Dysfunction of CECs leads to stromal decompensation, loss of transparency and corneal blindness. Corneal endothelium has low proliferative potential compared to surface epithelial cells leading to poor regeneration of CEC following injury. Additionally, the tissue exhibits age related decline in endothelial cell density with re-organisation of the cell layer, but no regeneration. The mechanisms which control proliferation and differentiation of neural crest derived CEC progenitors are yet to be clearly elucidated. Prdm (Positive regulatory domain) family of transcriptional regulators and chromatin modifiers are important for driving differentiation of a variety of cellular types. Many Prdm proteins are expressed in specific precursor cell populations and are necessary for their progression to a fully differentiated phenotype. In the present work, we sought to identify members of the Prdm gene family which are specifically expressed in human (h) CECs with a view to begin addressing their potential roles in CEC biology, focussing especially on Prdm 4 and 5 genes. By performing semi-quantitative reverse transcription coupled to PCR amplification we found that in addition to Prdm4 and Prdm5, Prdm2 and Prdm10 genes are expressed in hCECs. We further found that cultured primary hCECs or immortalised HCEC-12 cells express all of the Prdm genes found in CECs, but also express additional Prdm transcripts. This difference is most pronounced between Prdm gene expression patterns of CECs isolated from healthy human corneas and immortalised HCEC-12 cells. We further investigated Prdm 4 and Prdm 5 protein expression in cultured primary hCECs and HCEC-12 cells as well as in a human cadaveric whole cornea. Both Prdm 4 and Prdm 5 are expressed in human corneal endothelium, primary hCECs and in HCECs-12 cells, characterised by expression of the Na+/K+-ATPase. We observed that both proteins exhibit cytosolic (intracellular, but non-nuclear and distinct from extracellular fluid) as well as nuclear localisation within the endothelial layer, with Prdm 5 being more concentrated in the nuclei of the endothelial cells than Prdm 4. Thus, our work identifies novel Prdm genes specifically expressed in corneal endothelial cells which may be important in the control of CEC differentiation and proliferation.

Bilateral rupture of the posterior capsule and intraocular lens dislocation from excessive eye rubbing.

UNLABELLED: We report an unusual case of a 36-year-old woman with severe atopic eczema who developed sudden-onset reduction of vision in the right eye following excessive eye rubbing 9 years after cataract surgery. Examination identified posterior capsule rupture with dislocation of the intraocular lens (IOL) posteriorly into the vitreous cavity in the right eye and posterior capsule rupture with mild dislocation of the IOL in the bag in the left eye. To our knowledge, this is the first reported case of simultaneous bilateral posterior capsule rupture following uneventful surgery and secondary to eye rubbing. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Visual Outcomes and Graft Thickness in Microthin DSAEK--One-Year Results.

PURPOSE: To evaluate visual outcomes, endothelial graft thickness, and complications in microthin Descemet stripping automated endothelial keratoplasty (DSAEK). METHODS: A prospective interventional cohort of 130 eyes of 114 consecutive patients underwent microthin DSAEK. Endothelial graft preparation included pachymetry-controlled stromal dehydration to reduce donor thickness between 550 and 530 µm by a custom airflow device, before a single-pass microkeratome dissection with a uniform cutting head of 350 µm to achieve microthin endothelial grafts (<130 µm). Data on visual acuity, graft thickness, endothelial cell loss, and complication rates were analyzed. RESULTS: Pachymetry-controlled donor preconditioning reduced donor thickness on average by 67 µm (range 0-186, SD 44.7) from 590 µm (range 485-806, SD 53) to 528 µm (range 480-620, SD 23), P < 0.01, and allowed graft preparation without any case of intraoperative graft loss or perforation. The resultant mean graft thickness was 94 µm (SD 25) intraoperatively, 94 µm (SD 26) at 1 month, and 90 µm (SD 19) at 12 months. Of note, 98.2% of eyes without significant visual comorbidity achieved best-corrected Snellen acuity of 6/9 or more at 12 months. There was a 35.8% and 41% reduction in endothelial cell density at 3 and 12 months, respectively. Postoperative graft detachment occurred in 5% of cases (1.7% in uncomplicated eyes). There was no graft loss during preparation, and none developed immune rejection during the study period. CONCLUSIONS: The microthin DSAEK procedure offers a simple and safe technique to prepare thin endothelial grafts with a low risk of graft wastage, low risk of postoperative detachment, and visual results that are comparable to those of other thin endothelial keratoplasty procedures.

Cambridgeshire cataract shared care model: community optometrist-delivered postoperative discharge scheme.

BACKGROUND/AIMS: To evaluate a community optometrist-delivered postoperative discharge scheme in patients who underwent same day discharge from the hospital eye service (HES) following cataract surgery. METHODS: A service-level agreement (SLA) was agreed between the HES, primary care trust and community optometrists in Cambridgeshire regarding community follow-up after cataract surgery. Patients undergoing uncomplicated surgery with no significant ocular comorbidity were eligible for same day discharge to community optometrists. Feedback return rate and unintended medical interventions were assessed using an electronic medical record system. RESULTS: Over a 23-month period, a total of 1492 of 2461 (60.6%) Cambridgeshire patients were discharged to the community on the day of cataract surgery. Complete postoperative feedback was available in 96.85% of these patients. Uneventful postoperative recovery was recorded in 93.77% of patients with 2.95% of patients re-referred. Rates of cystoid macular oedema, uveitis and raised intraocular pressure were 0.6%, 1% and 0.1%, respectively. No patients had sight-threatening complications in this study. CONCLUSIONS: Postcataract surgery follow-up by community optometrists provides the advantages of care closer to home and avoids unnecessary hospital visits for patients undergoing uncomplicated cataract surgery.

Preconditioned donor corneal thickness for microthin endothelial keratoplasty.

PURPOSE: To describe a novel surgical technique to produce thin endothelial grafts for Descemet stripping automated endothelial keratoplasty (DSAEK). METHODS: Thirteen human cadaveric corneas in organ culture were randomized into conventional (n = 7) and microthin (n = 6) DSAEK groups. Grafts in the conventional DSAEK group were prepared using the conventional DSAEK technique of a single microkeratome pass with a 350-µm cutting head. Corneas in the microthin group were preconditioned to achieve a target central thickness of 530 µm before graft dissection with a 350-µm microkeratome head. Preconditioning involved stromal dehydration under pachymetric control using sterile airflow for 15-second increments. Donor and graft thicknesses were assessed with optical coherence tomography, and endothelial viability with trypan blue and alizarin red staining. RESULTS: Mean endothelial graft thickness obtained using the microthin DSAEK technique was 106 µm (SD, 32 µm) compared with 177 µm (SD, 33 µm) obtained using conventional DSAEK technique (P = 0.0024). Donor preconditioning yielded a predicted reduction of 100 µm in graft stromal thickness at a rate of 1.5 µm/s and mean duration of 72 seconds. The average anterior lamella thickness (cut depth) obtained in microthin and conventional DSAEK groups were 424 and 431 µm, respectively (P = 0.84). There was no difference in endothelial viability between the 2 groups. There were no corneal perforations during graft preparation in this study. CONCLUSIONS: Donor preconditioning by pachymetry-controlled stromal dehydration achieved significantly thinner endothelial grafts compared with the conventional DSAEK technique without compromise to endothelial viability or graft wastage.

Congenital unilateral corneal anaesthesia with microphthalmos: a case report.

Congenital corneal anaesthesia (CCA) is an uncommon condition difficult to diagnose. We report the case of a 20-month-old boy who presented with unilateral congenital corneal anaesthesia. The child was referred with a persistent corneal epithelial defect, unresponsive to symptomatic local treatment for over 10 months. Intensive topical treatment and strict corneal protection led to quick corneal healing. Congenital corneal anaesthesia occurs either alone or in association with neurological diseases or systemic congenital abnormalities. It is important to search for corneal anaesthesia in children with chronic ulcerations of the cornea and self-inflicted injuries. Early diagnosis and treatment are important due to the risk of poor visual prognosis. Management of CCA should aim for the prevention of epithelial defects and is a life-long process.

Release of vancomycin and gentamicin from a contact lens versus a fibrin coating applied to a contact lens.

PURPOSE: To develop a contact lens capable of releasing antibiotics for a minimum of 8 hours for the treatment of bacterial keratitis. METHODS: Fibrin gel was loaded with vancomycin or gentamicin and then shaped into a curved disc. The disc was then used to coat the surface of a commercial contact lens or was sealed between two lenses. Separate contact lenses were soaked in solutions of vancomycin or gentamicin. The in vitro release kinetics for each system was determined using PBS at 37°C and a particle-enhanced turbidimetric inhibition immunoassay. The bioactivity of the antibiotics released from the fibrin was confirmed by using a microbiological assay. RESULTS: Vancomycin and gentamicin were released at similar rates from soaked contact lenses and a coating of fibrin gel; however, the amounts of antibiotic delivered by the two systems differed considerably. The fibrin coating released over three times more gentamicin but less than one-fifth that of the lenses soaked in vancomycin. When fibrin was encapsulated between two contact lenses, significantly more controlled release was observed. For all systems, bactericidal amounts of vancomycin and gentamicin were released throughout the three-day testing period. CONCLUSIONS: As a delivery system, fibrin gel loaded with gentamicin performs better than contact lenses soaked in gentamicin. The opposite is true for vancomycin, where soaked lenses outperform fibrin gel. These systems could potentially be used as a treatment for bacterial keratitis.

Riboflavin/UVA collagen cross-linking-induced changes in normal and keratoconus corneal stroma.

PURPOSE: To determine the effect of Ultraviolet-A collagen cross-linking with hypo-osmolar and iso-osmolar riboflavin solutions on stromal collagen ultrastructure in normal and keratoconus ex vivo human corneas. METHODS: Using small-angle X-ray scattering, measurements of collagen D-periodicity, fibril diameter and interfibrillar spacing were made at 1 mm intervals across six normal post-mortem corneas (two above physiological hydration (swollen) and four below (unswollen)) and two post-transplant keratoconus corneal buttons (one swollen; one unswollen), before and after hypo-osmolar cross-linking. The same parameters were measured in three other unswollen normal corneas before and after iso-osmolar cross-linking and in three pairs of swollen normal corneas, in which only the left was cross-linked (with iso-osmolar riboflavin). RESULTS: Hypo-osmolar cross-linking resulted in an increase in corneal hydration in all corneas. In the keratoconus corneas and unswollen normal corneas, this was accompanied by an increase in collagen interfibrillar spacing (p<0.001); an increase in fibril diameter was also seen in two out of four unswollen normal corneas and one unswollen keratoconus cornea (p<0.001). Iso-osmolar cross-linking resulted in a decrease in tissue hydration in the swollen normal corneas only. Although there was no consistent treatment-induced change in hydration in the unswollen normal samples, iso-osmolar cross-linking of these corneas did result in a compaction of collagen fibrils and a reduced fibril diameter (p<0.001); these changes were not seen in the swollen normal corneas. Collagen D-periodicity was not affected by either treatment. CONCLUSION: The observed structural changes following Ultraviolet-A cross-linking with hypo-osmolar or iso-osmolar riboflavin solutions are more likely a consequence of treatment-induced changes in tissue hydration rather than cross-linking.

Ex vivo expansion and transplantation of limbal epithelial stem cells.

OBJECTIVE: To determine, using objective measures, the outcome of ex vivo cultured limbal epithelial stem cell (LESC) transplantation performed in compliance with good manufacturing practice using a novel culture system without 3T3 feeder cells. DESIGN: Prospective, noncomparative, interventional case series. PARTICIPANTS: Ten eyes of 10 patients with profound LESC deficiency arising from chemical injury (4 eyes), aniridia (3 eyes), ectodermal dysplasia (1 eye), Reiger's anomaly with Pax6 haploinsufficiency (1 eye), and unknown cause (1 eye). METHODS: Allogeneic (7 eyes) or autologous (3 eyes) corneal LESCs were cultured on human amniotic membrane. Tissue was transplanted to the recipient eye after superficial keratectomy. Impression cytology and confocal microscopy were performed 6 months after surgery with clinical follow-up to 13 months. Success was defined as an improvement in the defined clinical parameters of LESC deficiency, an improvement in visual acuity, the restoration of a more normal corneal phenotype on impression cytology, and the appearance of a regular hexagonal basal layer of cells on corneal confocal microscopy. MAIN OUTCOME MEASURES: Clinical parameters of LESC deficiency (loss of epithelial transparency, superficial corneal vascularization, epithelial irregularity, and epithelial breakdown), visual acuity, impression cytology and cytokeratin expression profiles, and in vivo confocal corneal confocal microscopy. RESULTS: The success rate using this technique was 60% (autografts 33%, allografts 71%). All patients with a successful outcome experienced an improvement in visual acuity of >/=2 lines Snellen acuity. Preoperatively, CK3+ and CK19+ cells accounted for 12+/-2.4% (mean +/- standard error of the mean) and 80+/-2.15% of cells, respectively, whereas postoperatively these accounted for 69+/-6.43% (P<0.0001) and 30+/-6.34% (P<0.0001) of cells, respectively. Goblet cells accounted for 8+/-1.19% of cells preoperatively and 1+/-0.35% of cells postoperatively (P<0.0001). CONCLUSIONS: These data demonstrate that it is possible to culture LESCs ex vivo in compliance with good manufacturing practice regulations. A set of objective outcome measures that confirm the efficiency of this technique in treating LESC deficiency is described. The widespread use of such standardized and objective outcome measures would facilitate a comparison between the different culture methods in use.

Interocular axial length difference and age-related cataract.

PURPOSE: To evaluate interocular differences in axial length and its relation to increasing axial length and postoperative refractive predictability in patients with age-related cataract. SETTING: Moorfields Eye Hospital, London, United Kingdom. METHODS: Preoperative biometry and postoperative refractive outcomes were analyzed in a consecutive series of 1537 patients who had uneventful bilateral phacoemulsification. In 1379 patients with bilateral data, the difference in axial lengths between eyes and the magnitude of postoperative anisometropia were compared between 1.0 mm incremental groups of axial length using the longer eye as the index eye. The postoperative refraction prediction error in 1457 left eyes was assessed in similar axial length groups. RESULTS: The difference in axial length was 0.3 mm or greater in 331 patients (24%). Axial length asymmetry between eyes increased with an increase in axial length in the index eye (P<.001). The 95th centile of the axial length difference was 0.5 mm when the longer eye was 22.0 mm or less and 4.0 mm when it was 28 mm or greater. There was also an increase in postoperative anisometropia with increasing axial length (P = .003). The median was 0.34 D (interquartile range [IR], 0.25-1.11) when the longer eye had an axial length of less than 28.0 mm and 0.66 D (IR, 0.16-0.66) when the longer eye had an axial length of 28.0 mm or more. In left eyes, there was an increase in biometry prediction error with an increase in axial length (P = .006). CONCLUSION: An increase in axial length was associated with greater asymmetry between eyes and more postoperative anisometropia, especially in eyes with an axial length greater than 28.0 mm.

Cellular effects of mitomycin-C on human corneas after photorefractive keratectomy.

PURPOSE: To investigate the effects of mitomycin-C (MMC) on epithelial and keratocyte cell kinetics after photorefractive keratectomy (PRK) using an in vitro human cornea model. SETTING: Department of Academic Ophthalmology, Rayne Institute, St. Thomas' Hospital, London, United Kingdom. METHODS: Twenty-four human eye-bank corneas were placed in a specially designed acrylic corneal holder and cultured using the air-interface organ culture technique for up to 4 weeks. The corneas were divided into 3 groups. Group 1 consisted of 8 human corneas that had -9.00 diopter (D) myopic PRK without MMC application. Group 2 consisted of 8 corneas that had -9.00 D PRK with MMC (0.2 microg/mL) application for 1 minute on the stromal surface after ablation. Group 3 consisted of 8 corneas that had -9.00 D PRK with 2-minute exposure to MMC (0.2 microg/mL). Temporal events in epithelial and keratocyte cell kinetics were evaluated using digital imaging, confocal microscopy, and light microscopy. RESULTS: Epithelial latency was significantly delayed with MMC application in Groups 2 and 3 (P<.001). Epithelial migration was delayed in Group 3 (2-minute exposure) compared to migration in Group 2 (P<.04), with a consequent delay in epithelial closure (P<.001). Group 3 corneas had poorly differentiated epithelium that was significantly thinner than in Groups 1 and 2 (P<.0001). A significant delay in keratocyte regeneration occurred after MMC application (P<.0005). At 4 weeks, the anterior stromal cell density was significantly lower in Group 3 than Group 2 (P<.001). There were no significant differences in the mid- and posterior stromal keratocyte density between the groups. CONCLUSIONS: Results suggest that epithelial healing after MMC is characterized by prolonged latency and decreased migration rate dependent on exposure time. Mitomycin C application did not result in increased loss of keratocytes, but it significantly delayed keratocyte repopulation in the anterior stroma. The use of MMC 0.2 microg/mL for 1 minute resulted in optimum modulation of healing characterized by reduced keratocyte activation with normal epithelial differentiation.