Intraocular lens power calculation in patients with irregular astigmatism.

PURPOSE: Accurate intraocular lens (IOL) calculation in subjects with irregular astigmatism is challenging. This study evaluated the accuracy of using Scheimpflug-derived central 2-mm equivalent keratometry reading (EKR) values for IOL calculation in irregular astigmatism. METHODS: This retrospective study included subjects (31 eyes of 30 patients) who underwent cataract surgery and IOL calculation using the 2-mm central EKR methods. We compared prediction error (PE) and absolute PE (APE) outcomes using SRK/T and Barrett Universal II formulas for keratometry data obtained from the IOLMaster 500 and Pentacam (anterior corneal sim k) devices. RESULTS: Cataract surgery and IOL calculation using the 2-mm central EKR methods resulted in improved visual acuity (uncorrected: from 1.13 ± 0.38 to 0.65 ± 0.46 logMar, p < 0.01; best-corrected: from 0.45 ± 0.24 to 0.26 ± 0.20 logMar, p < 0.01) after surgery. The percentage of subjects with best-corrected visual acuity of 6/6 was 22%, < 6/9 was 58%, and < 6/12 was 71%. For both the SRK/T and the Barrett formulas, the PE was similar to those obtained by IOLMaster (> 0.14) but lower than those obtained by the anterior corneal sim k (p < 0.02). IOLMaster provided keratometry reading in only 23/31 (74.1%) of cases. CONCLUSIONS: The use of Scheimpflug central 2-mm EKR for IOL calculation in irregular astigmatism was beneficial in terms of visual acuity improvement. It had comparable refractive prediction performance to the IOLMaster 500 and better than the anterior corneal sim K. The 2-mm EKR method can be used when IOLMaster cannot provide a reliable reading in abnormal corneas.

Progression of Pediatric Keratoconus After Corneal Cross-Linking: A Systematic Review and Pooled Analysis.

PURPOSE: Corneal collagen cross-linking (CXL) is an effective treatment to slow down keratoconus (KC) progression in adults. Several studies have also shown efficacious outcomes in pediatric populations, yet no systematic analysis has been performed and no accepted definition for progression is available in children after CXL. This study aimed to establish the most commonly used criteria for progression and to conduct a systematic review of the literature with pooled analysis to assess children's keratoconus progression after CXL. METHODS: A systemic literature review combined with pooled analysis was performed on full-length studies of KC after CXL treatment in a pediatric population and the methods used to report progression were analyzed. RESULTS: Thirty-seven studies (2078 eyes) were identified on the rates of KC progression after CXL. The most common method to report progression was increased Kmax, Kmean, or Ksteep by ≥1.0 diopter (78.3% of studies). Using these criteria, the mean pooled progression rate after epithelium-off CXL was 9.9% (95% confidence interval: 6.1% -14.6%, total pooled sample size: 1508 eyes) with high heterogeneity between studies [I 2 = 86.48% (95% confidence interval: 80.98 - 90.39), P < 0.0001]. CONCLUSIONS: When considering KC progression after CXL in children, with an increase in Kmax, Kmean, or Ksteep ≥ 1.0 diopter, the progression risk was roughly 10%. We encourage clear quantitative reporting of KC progression in future studies evaluating CXL efficacy in pediatric populations.

Assessing visible aerosol generation during vitrectomy in the era of Covid-19.

OBJECTIVE: To assess visible aerosol generation during simulated vitrectomy surgery. METHODS: A model comprising a human cadaveric corneoscleral rim mounted on an artificial anterior chamber was used. Three-port 25 gauge vitrectomy simulated surgery was performed with any visible aerosol production recorded using high-speed 4K camera. The following were assessed: (1) vitrector at maximum cut rate in static and dynamic conditions inside the model, (2) vitrector at air-fluid interface in a physical model, (3) passive fluid-air exchange with a backflush hand piece, (4) valved cannulas under air, and (5) a defective valved cannula under air. RESULTS: No visible aerosol or droplets were identified when the vitrector was used within the model. In the physical model, no visible aerosol or droplets were seen when the vitrector was engaged at the air-fluid interface. Droplets were produced from the opening of backflush hand piece during passive fluid-air exchange. No visible aerosol was produced from the intact valved cannulas under air pressure, but droplets were seen at the beginning of fluid-air exchange when the valved cannula was defective. CONCLUSIONS: We found no evidence of visible aerosol generation during simulated vitrectomy surgery with competent valved cannulas. In the physical model, no visible aerosol was generated by the high-speed vitrector despite cutting at the air-fluid interface.

Reducing visible aerosol generation during phacoemulsification in the era of Covid-19.

OBJECTIVE: To assess potential methods of reducing visible aerosol generation during clear corneal phacoemulsification surgery in the era of Covid-19. METHODS: Aerosol generation during phacoemulsification was assessed using a model comprising a human cadaveric corneoscleral rim mounted on an artificial anterior chamber. Typical phacoemulsification settings were used and visible aerosol production was recorded using high-speed 4K camera. Aerosolisation was evaluated under various experimental settings: Two different phacoemulsification tip sizes (2.2, 2.75 mm), varying levels of corneal moisture, the use of suction and blowing air in the surgical field, the use of hydroxypropyl methylcellulose (HPMC) coating of the cornea with a static and moving tip. RESULTS: This model demonstrates visible aerosol generation during phacoemulsification with a 2.75-mm phacoemulsification tip. No visible aerosol was noted with a 2.2-mm tip. The presence of visible aerosol was unrelated to corneal wetting. Suction in close proximity to the aerosol plume did not impact on its dispersion. Blowing air redirected the aerosol plume toward the ocular surface. Visible aerosol production was abolished when HPMC was used to coat the cornea. This effect lasted for an average of 67 ± 8 s in the static model. Visible aerosol generation was discerned during movement of the 2.2-mm tip toward the corneal wound. CONCLUSIONS: We demonstrate visible aerosol production in the setting of a model of clear corneal phacoemulsification. Visible aerosol can be reduced using a 2.2-mm phacoemulsification tip and reapplying HPMC every minute during phacoemulsification.

Assessment of the accuracy of new and updated intraocular lens power calculation formulas in 10 930 eyes from the UK National Health Service.

PURPOSE: To compare the accuracy of new/updated methods of intraocular lens (IOL) power calculation (Kane, Hill-RBF 2.0, and Holladay 2 with new axial length adjustment) with that of established methods (Barrett Universal II, Olsen, Haigis, Holladay 1, Hoffer Q, and SRK/T). SETTING: Bristol Eye Hospital, University Hospitals Bristol National Health Service, Foundation Trust, Bristol, UK. DESIGN: Retrospective consecutive case series. METHODS: Data from patients having uneventful cataract surgery with the insertion of 1 of 4 IOL types were included. Optimized IOL constants were used to calculate the predicted refraction of each formula for each patient. This was compared with the actual refractive outcome to give the prediction error. A subgroup analysis occurred based on the axial length and IOL type. RESULTS: The study included 10 930 eyes of 10 930 patients with the Kane formula having the lowest mean absolute prediction error (MAE), which was statistically significant (P < .001 in all cases) followed by the Hill 2.0, Olsen, Holladay 2, Barrett Universal 2, Holladay 1, SRK/T, Haigis, and Hoffer Q formula. The percentage of eyes predicted within ±0.5 D was Kane, 72%; Hill 2.0, 71.2%; Olsen, 70.6%; Holladay 2, 71%; Barrett 2, 70.7%; SRK/T, 69.1%; Haigis, 69%; and Hoffer Q, 68.1%. The Kane formula had the lowest MAE for short, medium, and long axial length subgroups and for each IOL type assessed. The updated versions of the Holladay 2 and Hill 2.0 formulas have resulted in improved accuracy. CONCLUSIONS: Overall and in each axial length subgroup, the Kane formula was more accurate than the other formulas.

Bristle Worm-Induced Keratouveitis: A Case Report.

PURPOSE: To report keratouveitis arising from corneal penetration by a bristle worm seta (bristle). METHODS: We report on a 64-year-old woman presenting with uniocular pain, redness, reduced vision, discharge, and pustular rash of the hands after cleaning out her marine aquarium containing bristle worms and rubbing her eye. RESULTS: Slit-lamp biomicroscopy showed pseudomembranous conjunctivitis, corneal punctate erosions, stromal infiltrate, and edema, but no visible foreign body. The anterior chamber developed 3+ cells with hypopyon within 24 hours. Laboratory testing of corneal and hand samples was negative. In vivo confocal microscopy revealed a hair-like seta in the anterior corneal stroma, 25 to 105 µm wide, with surrounding inflammatory cells. Anterior chamber washout was performed. Topical prednisolone 0.5% was commenced, and corneal edema gradually resolved over 3 months. CONCLUSIONS: Bristle worms thrive as detritivores in marine aquarium sediment. Aquarium owners risk touching their setae during tank cleaning. Ophthalmia nodosa describes ocular reaction to caterpillar, vegetable, and spider hairs: features include posterior migration of hairs, granulomatous inflammation, and uncertain prognosis. Eye specialists should be alerted to the possibility of bristle worm-induced ophthalmia nodosa. Confocal microscopy may be useful in identifying microscopic setae.

An 11-year analysis of microbial keratitis in the South West of England using brain-heart infusion broth.

BACKGROUND: The aims of this study were to identify the organisms responsible for microbial keratitis, as identified by corneal scrape using brain-heart infusion broth, trends over time and antimicrobial sensitivities, over an 11-year period at two eye units in the South West of England; Bristol Eye Hospital and Royal United Hospital, Bath. METHODS: All corneal scrapes performed and sent for microbiological analysis between 4th April 2006 and 31st October 2017 at the two eye units were retrospectively reviewed. First-line treatment was monotherapy with levofloxacin 0.5% and second-line treatment was a combination of cefuroxime 5% and gentamicin 1.5%. Both direct and enrichment cultures were used. RESULTS: In total, 2614 corneal scrapes from 2116 patients (1082 female, mean age 47.7 ± 21.2 years) were identified. 38.1% (n = 996) were culture positive and 1195 organisms were cultured. In all, 91.6% were bacteria (69.4% were gram-positive, 30.6% gram-negative). Coagulase-negative Staphylococci (CoNS) were the most commonly cultured organism (n = 430). Pseudomonas aeruginosa was the most commonly identified gram-negative organism (n = 189). In total, 6.9% (n = 83) of organisms cultured were fungi. In all, 1.4% (n = 17) were acanthamoeba. There was no statistically significant trend in the organisms observed over the study period. Sensitivity testing confirmed reasonable sensitivity to the empiric antibiotics used in clinical practice. CONCLUSIONS: This is the first report on microbial keratitis trends in the South West of England. Virulent organisms were likely to be detected on direct culture, whereas low virulent organisms such as CoNS were more likely to be detected on enrichment alone. Antibiotic sensitivity testing confirmed fluoroquinolone monotherapy as appropriate first-line treatment.

Calcification of hydrophilic acrylic intraocular lenses following secondary surgical procedures in the anterior and posterior segments.

AIMS: To report 15 cases of intraocular lens (IOL) calcification following intraocular surgery and to identify common risk factors. METHODS: A retrospective case review of patients with IOL calcification reported from the Royal Victorian Eye and Ear Hospital, Melbourne, Australia, and six surgeons in private practice in the Australian states of Victoria, New South Wales and Queensland. RESULTS: 15 cases of IOL calcification were identified. Eight cases were in hydrophilic acrylic IOLs and seven in hydrophilic acrylic IOLs with hydrophobic surface properties. Five cases occurred following intraocular injection of gas during endothelial keratoplasties. Two cases occurred following pars plana vitrectomy where gas was used. The remaining eight cases did not involve the injection of any intraocular gas; six cases were following trabeculectomy surgery, and two cases were after insertion of a 'piggyback' sulcus IOL. In each case, the calcification had a characteristic pattern, being centrally placed in the pupillary zone, mainly affecting the anterior lens surface. CONCLUSION: The aetiology of IOL calcification is not fully understood, although there are known risk factors such as using hydrophilic acrylic materials and the use of intraocular gas. Surgical consideration of a patient's ocular comorbidities before IOL implantation is an important tool to mitigate some of this risk.

Peripheral ulcerative keratitis with corneal melt as the primary presentation in a case of human immunodeficiency virus.

Peripheral ulcerative keratitis (PUK) is an aggressive, potentially sight-threatening cause for peripheral corneal thinning. It is thought to be the result of immune complex deposition at the limbus, resulting in corneal inflammation and stromal melt. We present a case of a 43-year-old female patient of African origin, presenting with PUK and associated corneal perforation as the primary presentation of HIV infection. An urgent tectonic deep anterior lamellar keratoplasty was performed under general anaesthesia with excellent outcome. The patient was referred to the sexual health clinic and anti-retroviral treatment was initiated. This case is to the best of our knowledge the first report from the UK of PUK with corneal perforation as the primary presentation of HIV infection. As highlighted in this report, infection with HIV may initially be silent; therefore, it is vital to consider HIV infection when dealing with PUK of unknown aetiology.

Cataract extraction after deep sclerectomy and its effect on intraocular pressure control.

PURPOSE: To estimate the incidence and predisposing factors for cataract extraction (CE) after Deep Sclerectomy (DS) with Mitomycin-C (MMC) and its effect on intraocular pressure (IOP) control. METHODS: Retrospective study of phakic eyes which had DS with MMC performed over a 5-year period. 179 eyes of 179 patients were included. RESULTS: Mean age at time of DS was 68.6 ± 9.7 years and mean follow-up was 89.4 ± 29.4 months. 63 eyes had CE and the probability of CE following DS was 0% at 1, 11.6% at 3, 21.0% at 5 and 33.2% at 7 years, with a 50% probability (median survival time) of 10 years. Age was association with increased risk for CE (Hazard ratio 1.05, 95% CI: 1.03-1.08, p < 0.0001). Mean IOP had increased from 11 mmHg to 15 mmHg in the first 3 months and remained higher up to a year (p < 0.001). There was no difference in the probability of maintaining an IOP < 16 mmHg without additional medications or needle revision (p = 0.05,Log-rank test). 20/47 eyes that failed were from the CE group, of which 14 (22.2%) failed prior to CE. Number of eyes on glaucoma medications before CE was 6 (mean edications 0.2 ± 0.5 m) and by last follow-up, 9 eyes were on medications (mean medications 0.2 ± 0.7). Post-CE needle revision was performed on 4 eyes. CONCLUSIONS: The probability of CE after DS is low, with a gradual increase with time. Increasing age was found to be a statistically significant risk factor. There was a modest increase in IOP after CE and increase use of glaucoma medications.

The successful treatment of a multidrug-resistant Achromobacter xylosoxidans corneal ulcer with topical meropenem.

Microbial keratitis is a common corneal condition, with many known risk factors. We present a case of an 88-year-old female patient with a multidrug-resistant Achromobacter xylosoxidans corneal ulcer in a previously failed second penetrating keratoplasty, successfully managed with topical meropenem drops administered hourly around the clock, for five days preceding and then hourly day only, for five days following a repeat third penetrating keratoplasty. Topical meropenem 50 mg/mL was prepared by mixing a 500 mg vial of meropenem with 10 mL of sterile water with pharmacy advice that administration should be within an hour. To the best of our knowledge, this is the first report of the use of topical meropenem in the management of A.xylosoxidans keratitis. This case highlights the importance of the mean inhibitory concentrations for antibiotics when considering sensitivities. Topical meropenem may be a useful treatment option for multidrug-resistant bacterial corneal ulcers that are resistant to conventional therapy.

The use of miltefosine in the management of refractory Acanthamoeba keratitis.

Acanthamoeba keratitis (AK) is a sight threatening infection most commonly affecting contact lens wearers. The authors report a case of intractable A.polyphaga and A.castellanii, with extensive intraocular spread, managed using oral miltefosine. A 59-year old male contact lens wearer was referred to the tertiary corneal service at Bristol Eye Hospital. Vision was hand movements on the left and 6/6 on the right. Clinical examination was consistent with left AK (confirmed by corneal scrape). Management included biguanide (polyhexamethylene biguanide (PHMB) 0.02%, later 0.06%) and diamidine (hexamidine 0.1%). Further treatment included imidazole (guttae voriconazole, oral posaconazole) and fortified biguanide (chlorhexidine 0.2%). Therapeutic PKP was performed. Microscopy revealed Acanthamoeba throughout host stroma. Corneal scrape and anterior chamber tap revealed persistent infection with Acanthamoeba. Intracameral voriconazole was administered twice. Clinically there was scleritis, with concerns regarding posterior segment involvement. There was a severe necrotic keratitis with almost complete corneal melt, requiring enucleation. Oral miltefosine was commenced to reduce the risk of transmission of Acanthamoeba beyond ocular structures at the time of the enucleation. Histopathological analysis detected A.polyphaga and A.castellanii in vitreous but not retina, choroid or optic nerve suggesting that infection had not progressed posteriorly through the ocular structures and the central nervous system was not involved. The use of miltefosine as a component of combination anti-parasitic therapy is associated with long-term survival in cases of Acanthamoeba infection of the central nervous system. This case reports its first systemic use in the United Kingdom in a case of severe intractable AK with intraocular spread.

Intraocular lens opacification after descemet stripping automated endothelial keratoplasty.

PURPOSE: Intraocular lens (IOL) opacification is a rare but serious complication that may necessitate its exchange. The use of intraocular gases is a known precipitant. Descemet stripping endothelial keratoplasty (DSAEK) involves injecting air into the anterior chamber. IOL opacification has been described after this procedure; however its incidence is currently unknown. METHODS: A retrospective review of case notes from a single center of all patients undergoing DSAEK, who were either already pseudophakic or had simultaneous cataract surgery. Cases with IOL opacification were analyzed, and any risk factors were identified. RESULTS: One hundred sixty-eight DSAEK were performed on 154 eyes of 137 patients. Fifty-four cases had simultaneous cataract surgery with implantation of an IOL. Fifteen (9.7%) eyes developed IOL opacification. This had a distinctive pattern, being limited to the anterior lens surface, in the pupillary zone. Median time interval from keratoplasty to the first observation of IOL opacification was 17 months (range, 4-34 months). The only statistically significant risk factor was rebubbling of detached endothelial grafts. Rebubbling was performed in 62.5% (10/15) of cases with IOL opacification, compared with 23% (32/139) with no opacification (P = 0.0009). CONCLUSIONS: This is the first study to report the incidence of IOL opacification after undergoing DSAEK. Although the mechanism is unknown, multiple injections of air into the anterior chamber statistically increase the risk of IOL opacification.