BCLA CLEAR Presbyopia: Management with corneal techniques.

Corneal techniques for enhancing near and intermediate vision to correct presbyopia include surgical and contact lens treatment modalities. Broad approaches used independently or in combination include correcting one eye for distant and the other for near or intermediate vision, (termed monovision or mini-monovision depending on the degree of anisometropia) and/or extending the eye's depth of focus [1]. This report provides an overview of the evidence for the treatment profile, safety, and efficacy of the range of corneal techniques currently available for managing presbyopia. The visual needs and expectations of the patient, their ocular characteristics, and prior history of surgery are critical considerations for patient selection and preoperative evaluation. Contraindications to refractive surgery include unstable refraction, corneal abnormalities, inadequate corneal thickness for the proposed ablation depth, ocular and systemic co-morbidities, uncontrolled mental health issues and unrealistic patient expectations. Laser refractive options for monovision include surface/stromal ablation techniques and keratorefractive lenticule extraction. Alteration of spherical aberration and multifocal ablation profiles are the primary means for increasing ocular depth of focus, using surface and non-surface laser refractive techniques. Corneal inlays use either small aperture optics to increase depth of field or modify the anterior corneal curvature to induce corneal multifocality. Presbyopia correction by conductive keratoplasty involves application of radiofrequency energy to the mid-peripheral corneal stroma which leads to mid-peripheral corneal shrinkage, inducing central corneal steepening. Hyperopic orthokeratology lens fitting can induce spherical aberration and correct some level of presbyopia. Postoperative management, and consideration of potential complications, varies according to technique applied and the time to restore corneal stability, but a minimum of 3 months of follow-up is recommended after corneal refractive procedures. Ongoing follow-up is important in orthokeratology and longer-term follow-up may be required in the event of late complications following corneal inlay surgery.

Comparison of 110- and 145-µm Small-Incision Lenticule Extraction Cap Thickness: A Randomized Contralateral Eye Study.

PURPOSE: To investigate the visual, refractive, and biomechanical outcomes of small incision lenticule extraction (SMILE) with two different cap thicknesses. METHODS: Thirty-four patients were included in this prospective, randomized, contralateral eye study. Subjects were randomized to receive SMILE surgery with a 110-m cap thickness in one eye and 145-µm cap thickness in the fellow eye. Uncorrected and corrected distance visual acuity, contrast sensitivity (CS), total higherorder aberrations (THOAs) and corneal biomechanical properties were compared 3 months after surgery. RESULTS: Postoperative refractive and visual outcomes, CS and THOAs were similar between the two groups ( P > 0.05 for all parameters). At 3 months postoperatively, there was a significant difference in Corvis ST Biomechanical Index (CBI); stiffness parameter at first applanation (SP A1), and Integrated Radius between the two groups (all P < 0.05). CONCLUSIONS: Eyes with thicker SMILE corneal caps showed no advantage regarding visual acuity, CS and THOAs over eyes with thinner caps. However, higher cap thickness may result in better corneal biomechanical properties postoperatively.

Keratoconus Management in the Community: A Survey of Optometrists.

OBJECTIVES: Defining the patterns of practice and referral criteria of optometrists within New Zealand to investigate the diagnosis and management of keratoconus. METHODS: Optometrists recruited through the New Zealand Association of Optometrists, Cornea and Contact Lens Society of New Zealand, and private practices were invited to complete an anonymous survey. RESULTS: Responses were received from 168 optometrists (representing 20.0% of the optometrist population). Half (48%) of optometrists had ≥15 years of experience, and 22% prescribed soft contact lenses daily, whereas only 6.4% prescribed rigid gas-permeable (RGP) lenses daily. The main barriers to prescribing RGPs were experience with fitting, low market demand, and patient discomfort. When referring to an ophthalmologist, 41% reported referring on progression of corneal parameters, 27% on initial diagnosis, 21% at no set time, and 10% with a reduction in visual acuity. Most optometrists (64%) would refer for possible surgery when visual acuity dropped between 6/9 and 6/12. Optometrists with greater experience were more likely to prescribe RGP lenses and co-manage patients with ophthalmologists. Ownership of a corneal imaging unit suggested an increased likelihood of prescribing RGP lenses but did not alter referral patterns. CONCLUSION: This survey provides an overview of current practice and highlights the importance of optometrists in the diagnosis and management of keratoconus. There was a significant discrepancy in keratoconus management, regarding optical correction modality and referral criteria for ophthalmology review. Further interdisciplinary work is required between optometry and ophthalmology to standardize referral guidelines and enhance visual outcomes.

Repeatability of Scheimpflug based corneal tomography parameters in advanced keratoconus with thin corneas.

OBJECTIVE: To determine the repeatability limits of corneal tomography parameters in patients with advanced and moderately thin keratoconic corneas to assist in planning thickness-based procedural interventions. METHODS: Prospective, single-centre, repeatability study. Three tomography scans using the Pentacam AXL were obtained from patients with keratoconus with thinnest corneal thickness (TCT) ≦400 µm (sub-400 group) and compared to those with TCT = 450-500 µm (450-plus group). Eyes with previous crosslinking, intraocular surgery, or acute corneal hydrops were excluded. Eyes were age and gender-matched. The within-subject standard deviations for flat keratometry (K1), steep keratometry (K2), maximal keratometry (Kmax), astigmatism and TCT were used to calculate respective repeatability limits (r). Intra-class correlation coefficients (ICC) were also analysed. RESULTS: The sub-400 group comprised 114 eyes from 114 participants, and the 450-plus group comprised 114 eyes from 114 participants. In the sub-400 group, TCT was amongst the least repeatable parameters (33.92 µm; ICC 0.96), compared with the 450-plus group (14.32 µm; ICC 0.99, p < 0.01). In the sub-400 group, K1 and K2 of the anterior surface were the most repeatable parameters (r 3.79 and 3.22 respectively; ICC 0.97 and 0.98 respectively) compared with the 450-plus group (r 1.17 and 0.92 respectively; and ICC 0.98 and 0.99 respectively, p < 0.01). CONCLUSIONS: The repeatability of corneal tomography measurements is significantly reduced in sub-400 keratoconic corneas when compared to 450-plus corneas. Repeatability limits should be carefully considered when surgical interventions are planned for such patients.

Therapeutic non-ectasia applications of cornea cross-linking.

Corneal cross-linking is a photopolymerization technique traditionally used to strengthen corneal tissue. Corneal cross-linking utilizes riboflavin (vitamin B2) as a photosensitizer and ultraviolet-A light (UVA) to create strong covalent bonds within the corneal stroma, increasing tissue stiffness. Multiple studies have demonstrated corneal cross-linking's effectiveness in treating corneal ectasia, a progressive, degenerative, and non-inflammatory thinning disorder, as quantified by key tomographic, refractive, and visual parameters. Since its introduction two decades ago, corneal cross-linking has surpassed its original application in halting corneal ectatic disease and its application has expanded into several other areas. Corneal cross-linking also possesses antibacterial, antienzymolytic and antioedematous properties, and has since become a tool in treating microbial keratitis, correcting refractive error, preventing iatrogenic ectasia, stabilising bullous keratopathy and controlling post keratoplasty ametropia. This review provides an overview of the current evidence base for the therapeutic non-ectasia applications of cornea cross-linking and looks at future developments in the field.

Agreement between a Spectral-Domain Ocular Coherence Tomography Biometer with a Swept-Source Ocular Coherence Tomography Biometer and an Optical Low-Coherence Reflectometry Biometer in Eyes with Cataract.

Purpose: To assess the agreement between biometric parameters measured by a spectral-domain optical coherence tomography optical biometer device (Optopol Revo NX) with a validated swept-source biometer (IOLMaster 700) and a validated optical low-coherence reflectometry biometer (Lenstar LS 900), in cataract surgery candidates. Methods: In this prospective comparative study, 100 patients (100 eyes) who were eligible for cataract surgery were involved. Bland-Altman plots were used to assess agreement between devices for biometric parameters including axial length (AL), anterior chamber depth (ACD), lens thickness (LT), and central corneal thickness (CCT). Results: AL measurements were successful in 82 eyes (82.0%) with Revo NX, in 91 eyes (91.0%) with Lenstar LS 900, and in 97 eyes (97.0%) with IOLMaster 700. When Revo NX was compared to IOL Master 700 and Lenstar LS 900, the mean differences were as follows: -0.02 ± 0.02 mm and -0.02 ± 0.03 mm (P = 0.313, P = 0.525) for AL, 0.01 ± 0.03 mm and 0.10 ± 0.03 mm (P = 0.691, P = 0.002) for ACD, -0.15 ± 0.03 mm and 0.001 ± 0.04 mm (P < 0.001, P = 0.95) for LT, and -2.29 ± 0.92 µm, and 0.73 ± 1.43 µm (P = 0.015, P = 0.612) for CCT. Three devices were highly correlated for AL, ACD, LT, and CCT (interclass correlation coefficient > 0.75). Bland-Altman plots showed a narrower 95% limit of agreement (-0.35 to 0.31) between Revo NX and IOLMaster 700 in measuring AL. Conclusions: Despite the higher measurement failure rate in eyes with cataract, the Revo NX showed very good agreement with the IOLMaster 700 and Lenstar LS 900 optical biometers in measuring AL, ACD, LT, and CCT. However, ACD and LT measurements cannot be considered interchangeable between these devices.

Corneal Crosslinking: Present and Future.

Keratoconus is a progressive corneal thinning disorder that can lead to vision loss. In the last 2 decades, corneal crosslinking (CXL) has emerged as an effective method to halt the progression of keratoconus and reduce the number of patients requiring keratoplasty. The procedure has been adopted globally and has evolved to become a part of combination treatments to regularize the cornea and improve visual outcomes. CXL has even been extrapolated in managing other ocular pathologies such as progressive myopia, infectious keratitis, and bullous keratopathy. This review aims to summarize the current role of CXL in keratoconus and its alternative uses, and provide insights into future developments in this fast-developing field.

The Vision Correction Questionnaire: an electronic patient-reported outcome measure for refractive surgery.

PURPOSE: To develop a psychometrically robust electronic patient reported outcome measure (ePROM) for refractive surgery. SETTING: Moorfields Eye Hospital, London, United Kingdom. DESIGN: Questionnaire development study. METHODS: Items were derived in 6 domains (spectacle dependence, visual quality, eye comfort, functional freedom, emotional wellbeing, and satisfaction with treatment) from existing Rasch adjusted instruments, patient and surgeon feedback, and refinement in semistructured interviews before administration to a field test cohort (n = 360) of patients undergoing routine refractive surgery. Spectacle dependence and satisfaction with treatment items were used to provide descriptive statistical information only. Contemporary criteria for item reduction and Rasch modeling were applied to the remaining domains. The finalized questionnaire was then administered to a second patient cohort (n = 120) before and after surgery to assess sensitivity to change. RESULTS: A 5-item scale derived for emotional wellbeing was unidimensional and a good fit to the Rasch model with ordered category response profiles, adequate precision (person separation 2.22 logits, reliability coefficient 0.83), and no misfitting items. Mean logit scores were 0.91 higher after treatment (effect size 1.26) suggesting a positive impact on emotional wellbeing. Functional scales could not be derived for visual quality, eye comfort, or functional freedom. Single-item ratings for visual quality and eye comfort were retained in our final 11-item questionnaire. CONCLUSIONS: This short ePROM should integrate well with routine clinical care and clinical trials in refractive surgery. The Rasch adjusted emotional wellbeing scale may help quantify the way patients feel about refractive surgery, with the remaining items providing useful descriptive information.

Flattening of Central, Paracentral, and Peripheral Cones After Non-accelerated and Accelerated Epithelium-off CXL in Keratoconus: A Multicenter Study.

PURPOSE: To assess the flattening of central, paracentral, and peripheral cones following non-accelerated (non-A-CXL) and accelerated (A-CXL) epithelium-off corneal cross-linking with 10 times higher intensity. METHODS: In this multicenter study of 200 eyes (100 in each group), following 10 minutes of soak time with riboflavin 0.1%, continuous CXL was performed for 30 minutes (intensity: 3 mW/cm2, fluence: 5.4 J/cm2) in the non-A-CXL group and 3 minutes (intensity: 30 mW/cm2, fluence: 5.4 J/cm2) in the A-CXL group. Anterior and posterior cone flattening were compared at 12 months. Multiple regression analysis was performed to establish correlation of age, sex, cone location, and preoperative maximum keratometry (Kmax) values with postoperative flattening at 12 months. RESULTS: In the non-A-CXL and A-CXL groups, central cones were the steepest, followed by paracentral and peripheral cones. Both groups showed significant flattening in central (1.54 ± 1.94 and 1.09 ± 1.79 diopters [D]) and paracentral (0.62 ± 1.59 and 0.55 ± 0.98 D) cones only. In the non-A-CXL group, there was a positive correlation between postoperative flattening and preoperative Kmax values, whereas paracentral and peripheral cone locations were negatively related. In the A-CXL group, only paracentral location was negatively correlated to postoperative flattening and showed posterior cone steepening at 12 months. CONCLUSIONS: Although central cones were the steepest in both groups, there was no difference in postoperative flattening between the groups for all cone locations. In the non-A-CXL group, postoperative flattening was proportional to preoperative Kmax values in central cones and was less with paracentral and peripheral locations. With A-CXL, postoperative flattening was less only with paracentral location. In the A-CXL group, significant posterior cone steepening was noticed only in paracentral cones. [J Refract Surg. 2022;38(5):310-316.].

Changes in Corneal Biomechanical Properties After Small-Incision Lenticule Extraction and Photorefractive Keratectomy, Using a Noncontact Tonometer.

PURPOSE: The aim of this study was to evaluate and compare early corneal biomechanical changes after small-incision lenticule extraction (SMILE) and photorefractive keratectomy (PRK). METHODS: The study comprised 74 patients eligible for refractive surgery, equally allocated to PRK (37 patients) and SMILE (37 patients). Corneal biomechanical properties were recorded and compared between the 2 groups at preoperatively and 3 months after surgery using a dynamic ultra-high-speed Scheimpflug camera equipped with a noncontact tonometer. RESULTS: Both procedures significantly affected corneal biomechanical properties at 3 months after surgery. Patients in the PRK group showed significantly better results for deformation amplitude ratio (DA ratio) ( P = 0.03), maximum inverse radius (InvRadMax) ( P = 0.02), and A2 time ( P = 0.03). The mean changes in DA ratio, HC radius, InvRadMax, and Ambrosio relational thickness were significantly higher in the SMILE group in comparison with those of the PRK group (all, P < 0.05). In both groups, change in CCT was significantly correlated with changes in DA ratio and InvRadMax ( P < 0.05). CONCLUSIONSS: Both SMILE and PRK refractive surgeries significantly altered corneal biomechanical properties but the changes were more prominent after SMILE.

Case Report: Successful Corneal Crosslinking in a Patient with Corneal Ectasia Associated with Stevens-Johnson Syndrome.

SIGNIFICANCE: Corneal ectasia can be a complication of Stevens-Johnson syndrome. When detected in a timely manner, corneal crosslinking can be a safe treatment. This is an important association to highlight that early diagnosis and treatment can prevent the need for invasive surgical procedures such as keratoplasty. PURPOSE: This study aimed to report a successful accelerated epithelium-off corneal crosslinking in a rare case of corneal ectasia secondary to Stevens-Johnson syndrome. CASE REPORT: A 25-year-old Indian man presented with a progressive visual acuity decline 5 years after an acute episode of Stevens-Johnson syndrome secondary to penicillin ingestion. Serial tomography scans confirmed the diagnosis of corneal ectasia. After the preparation of the ocular surface, which was deemed to have a mild degree of limbal stem cell deficiency, with frequent preservative-free lubrication and steroid use, accelerated epithelium-off crosslinking was performed with 4 minutes of continuous ultraviolet-A exposure at 30 mW/cm2 and a total energy dose of 7.2 J/cm2. Complete re-epithelialization was observed at 72 hours after crosslinking with no complications. Corneal tomography 15 months after treatment showed stabilization of ectasia, with improvement in visual acuity. CONCLUSIONS: Corneal ectasia is a rare but important complication of Stevens-Johnson syndrome. Accelerated epithelium-off crosslinking treatment can be considered in patients with a compromised ocular surface after Stevens-Johnson syndrome. Pre-operative optimization of the ocular surface and vigilant monitoring in the early post-operative period are recommended for the prevention of complications.

Microdroplet and spatter contamination during phacoemulsification cataract surgery in the era of COVID-19.

IMPORTANCE: Determine phacoemulsification cataract surgery risk in a Covid-19 era. BACKGROUND: SARS-CoV-2 (Covid-19) transmission via microdroplet and aerosol-generating procedures presents risk to medical professionals. As the most common elective surgical procedure performed globally; determining contamination risk from phacoemulsification cataract surgery may guide personal protection equipment use. DESIGN: Pilot study involving phacoemulsification cataract surgery on enucleated porcine eyes by experienced ophthalmologists in an ophthalmic operating theatre. PARTICIPANTS: Two ophthalmic surgical teams. METHODS: Standardized phacoemulsification of porcine eyes by two ophthalmologists accompanied by an assistant. Fluorescein incorporated into phacoemulsification irrigation fluid identifying microdroplets and spatter. Contamination documented using a single-lens reflex camera with a 532 nm narrow bandpass (fluorescein) filter, in-conjunction with a wide-field blue light and flat horizontal laser beam (wavelength 532 nm). Quantitative image analysis using Image-J software. MAIN OUTCOME MEASURES: Microdroplet and spatter contamination from cataract phacoemulsification. RESULTS: With phacoemulsification instruments fully within the eye, spatter contamination was limited to <10 cm. Insertion and removal of the phacoemulsification needle and bimanual irrigation/aspiration, with irrigation active generated spatter on the surgeons' gloves and gown extending to >16 cm below the neckline in surgeon 1 and > 5.5 cm below the neckline of surgeon 2. A small tear in the phacoemulsification irrigation sleeve, presented a worse-case scenario the greatest spatter. No contamination above the surgeons' neckline nor contamination of assistant occurred. CONCLUSIONS AND RELEVANCE: Cataract phacoemulsification generates microdroplets and spatter. Until further studies on SARS-CoV-2 transmission via microdroplets or aerosolisation of ocular fluid are reported, this pilot study only supports standard personal protective equipment.

Prospective Clinical Study of Keratoconus Progression in Patients Awaiting Corneal Cross-linking.

PURPOSE: Keratoconus progression should be treated with corneal cross-linking (CXL) in a timely manner. This study aimed to investigate patient factors associated with keratoconus progression between time of listing and at time of CXL. METHODS: Prospective observational study at a tertiary center. Ninety-six eyes of 96 patients with keratoconus. Demographic, clinical, and tomographic parameters were analyzed to determine the risk factors for keratoconus progression. Analyzed tomographic indices included steepest keratometry, average keratometry, cornea thinnest point, index of surface variance, index of vertical asymmetry, keratoconus index, center keratoconus index, index of height asymmetry, and index of height decentration. RESULTS: A total of 38 eyes (39.6%) were found to have keratoconus progression during an average waiting time of 153 ± 101 days. There were significant differences in preoperative tomographic parameters such as index of surface variance (111.3 ± 36.6 vs. 88.3 ± 31.8; P = 0.002), index of vertical asymmetry (1.1 ± 0.4 vs. 0.9 ± 0.4; P = 0.005), keratoconus index (1.31 ± 0.12 vs. 1.22 ± 0.11; P < 0.001), and index of height decentration (0.16 ± 0.07 vs. 0.11 ± 0.06; P = 0.015) between eyes that progressed and those that remained stable. There were no significant differences in steepest keratometry, average keratometry, cornea thinnest point, and center keratoconus index. Multivariate analysis did not reveal age, presence of atopy/atopic keratoconjunctivitis, eye rubbing, or waiting time to be a significant risk factor for progression; however, Maori ethnicity was a risk factor (odds ratio = 3.89; P = 0.02). CONCLUSIONS: A significant proportion of eyes were found to be progressing while waiting for CXL. A risk stratification score for patients awaiting CXL may reduce the risk of progression.

Prospective two year study of changes in corneal density following transepithelial pulsed, epithelium-off continuous and epithelium-off pulsed, corneal crosslinking for keratoconus.

PURPOSE: To compare the corneal densitometry changes after transepithelial pulsed (t-ACXL), epithelium-off continuous (c-ACXL) and epithelium-off pulsed (p-ACXL), accelerated corneal crosslinking for patients with progressive keratoconus. METHODS: Prospective, interventional case series at a university hospital tertiary referral center. Forty eyes received t-ACXL, 40 eyes received c-ACXL, and 40 eyes received p-ACXL. Corneal tomography, densitometry and visual acuity were evaluated preoperatively and at 1, 3, 6, 12 and 24 months postoperatively. RESULTS: Total densitometry values of the total layer over the annular diameters 0-12 mm expressed in grayscale units (GSU) showed no significant change after t-ACXL and p-ACXL but increased significantly after c-ACXL at 1 month (16.76 ± 2.38, P value < 0.01) and 3 months (16.12 ± 2.22, P value 0.04), returning to baseline levels at month 6 (14.97 ± 2.13, P value 0.99) and remained stable until final follow-up. At 1 month, the mean change in total densitometry value of the t-ACXL group (-0.53 ± 2.08) was significantly lower than the p-ACXL (0.70 ± 1.96 P value 0.04) and c-ACXL (1.97 ± 2.65 P value < 0.01). There was no statistical difference in the mean change in total densitometry between the three groups from 6 to 24 months. In the c-ACXL group, a higher degree of CXL-induced corneal haze at 1 month was observed in patients with steeper preoperative keratometry readings and in individuals where a greater flattening effect was achieved at 24 months. CONCLUSIONS: Continuous epithelium-off accelerated cornea crosslinking appears to induce more corneal haze than pulsed epithelium-off and transepithelial pulsed cornea crosslinking in the early postoperative period. Differences resolve by six-months.

Outcomes in randomised controlled trials of multifocal lenses in cataract surgery: the case for development of a core outcome set.

BACKGROUND/AIMS: To describe and summarise the outcomes reported in randomised controlled trials of multifocal versus monofocal intraocular lenses in cataract surgery. METHODS: We identified all randomised controlled trials of multifocal versus monofocal lenses in a Cochrane review (last search date June 2016). We extracted and summarised data on all outcomes reported using the framework of domain, measurement, metric and method of aggregation. RESULTS: All studies collected data on distance and near visual acuity but there was considerable variation in the measures used and whether these outcomes were unaided or best corrected. Most studies reported final value measurements, rather than change from baseline. Approximately half of the studies reported data as a continuous measure only, one-third reported both continuous and categorical measures and a minority reported categorical measures only. There was little consensus as to cut-points. Although a majority of studies included one or more patient-reported outcome measures, none of the studies reported patient involvement in the choice of outcomes. CONCLUSION: The collection and analysis of data on outcome measures in studies of multifocal intraocular lenses in cataract surgery are complicated. As a result, there is considerable heterogeneity in collection and reporting in the medical literature. This makes it difficult to synthesise such data to provide robust estimates of effect and is a potential source of research waste. Investigators in this field must produce a core outcome set that is informed by patients' views and we propose an initial set of outcomes on which these could be based.

Prospective 2-year study of accelerated pulsed transepithelial corneal crosslinking outcomes for Keratoconus.

AIMS: To report 2-year outcomes of transepithelial, accelerated, pulsed, corneal crosslinking (t-ACXL) for patients with progressive keratoconus. METHODS: Prospective, interventional case series at a university hospital tertiary referral centre. Forty eyes with progressive keratoconus undergoing t-ACXL were included. Treatment was performed with pulsed illumination (1 s on/1 s off) using 45 mW/cm2 for 5 min and 20 s, for a surface dose of 7.2 J cm2. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction spherical equivalent (MRSE), corneal tomography, anterior segment optical coherence tomography (OCT) and confocal microscopy were evaluated preoperatively and at 12 and 24 months postoperatively. RESULTS: The mean patient age was 23.32 ± 5.18 years (SD) (range 14-42 years). The mean CDVA significantly improved from 0.38 ± 0.32 logMAR at baseline to 0.30 ± 0.21 logMAR at 24 months (P < 0.01). There was no significant difference in UDVA, MRSE, asymmetry indices, tomographic parameters and endothelial density. The improvement in visual acuity was inversely correlated with preoperative CDVA and preoperative KMax. No complications were encountered. CONCLUSIONS: In this prospective study, t-ACXL appeared safe and effective in halting progression of keratoconus within a follow-up period of 24 months.

Prospective two-year study of clinical outcomes following epithelium-off pulsed versus continuous accelerated corneal crosslinking for keratoconus.

IMPORTANCE: Keratoconus is a debilitating condition with a disproportionately high impact on health resources and vision-specific quality of life. BACKGROUND: This study aimed to compare 2-year outcomes of epithelium-off pulsed (p-ACXL) and epithelium-off continuous (c-ACXL) accelerated corneal crosslinking in progressive keratoconus. DESIGN: Prospective, interventional case series. PARTICIPANTS: Eighty eyes of 80 patients were included. METHODS: The visual, refractive and tomographic results of the two crosslinking protocols were compared. MAIN OUTCOME MEASURES: Uncorrected distance visual acuity, corrected distance visual acuity (CDVA), manifest refraction spherical equivalent (MRSE) and maximum keratometry (KMAX ) on corneal tomography assessment. RESULTS: The mean patient age was 22.51 ± 6.12 years (SD) and 22.08 ± 5.72 years in the p-ACXL and c-ACXL groups, respectively. The mean CDVA significantly improved from 0.30 ± 0.16 logMAR at baseline to 0.23 ± 0.17 logMAR at 24 months (P = .04) in the p-ACXL group and from 0.36 ± 0.22 logMAR to 0.26 ± 0.27 logMAR (P = .02) in the c-ACXL group. The mean induced change in MRSE (+1.79 ± 2.30 D vs +0.27 ± 3.19 D, P = .04) and KMAX (-1.75 ± 1.80 D vs -0.39 ± 1.95 D, P = .04) were superior in the c-ACXL group compared to the p-ACXL group at 24 months. No complications were encountered. CONCLUSIONS AND RELEVANCE: In this prospective study, both p-ACXL and c-ACXL treatments were safe methods to halt the progression of keratoconus within a follow-up period of 24 months. c-ACXL appeared to offer superior refractive and tomographic outcomes when compared to p-ACXL but this did not translate into better visual outcomes.

Direct measurement of anterior corneal curvature changes attributable to epithelial removal in keratoconus.

PURPOSE: To compare the tomography of the corneal epithelium and Bowman layer in eyes with moderate to severe keratoconus before and after epithelial debridement. SETTING: University hospital tertiary referral center. DESIGN: Prospective case series. METHODS: Dual-channel Scheimpflug combined with Placido-disk tomography was used to measure the corneal variables in eyes with keratoconus having corneal crosslinking immediately before and after epithelial debridement. The differences in pachymetry, axial keratometry, astigmatism magnitude, asphericity, total corneal power, and spherical aberrations were computed. RESULTS: The study comprised 30 eyes of 30 patients. After epithelial removal, the central (0.0 to 4.0 mm) and midperipheral (4.0 to 7.0 mm) corneal zones were significantly thinner mean (21 µm ± 14 [SD] and 35 ± 44 µm, respectively). The mean anterior axial flat keratometry (K) (+1.71 diopters [D]), steep K (+2.14 D), maximum K (+2.13 D), corneal astigmatism (+1.11 D), asphericity (-0.31), and total corneal power changes (+2.03 D) were significantly different after epithelial debridement. There were no significant changes in posterior corneal flat K or steep K, posterior corneal astigmatism, or posterior asphericity. There were no significant differences in the mean astigmatic axis (anterior or posterior corneal surface) or spherical aberration after epithelial debridement. CONCLUSIONS: In eyes with moderate to severe keratoconus, the tomography of Bowman layer was significantly steeper than that of the epithelium; thus, epithelial debridement increased the magnitude of anterior corneal keratometry, astigmatism, and prolateness. These data suggest that the corneal epithelium smooths the underlying Bowman layer irregularity in keratoconus.

The rising tide of Acanthamoeba keratitis in Auckland, New Zealand: a 7-year review of presentation, diagnosis and outcomes (2009-2016).

IMPORTANCE: Acanthamoeba is an increasingly prevalent cause of vision-threatening microbial keratitis. BACKGROUND: To assess the incidence, clinical presentation, diagnosis and outcomes of patients with Acanthamoeba keratitis (AK) in Auckland, New Zealand over a 7-year period. DESIGN: Retrospective observational consecutive case series. PARTICIPANTS: Fifty-eight eyes of 52 patients diagnosed with AK. METHODS: All cases of AK were identified using a cross-referenced search of clinical, laboratory and pharmacy records from March 2009 to May 2016. MAIN OUTCOME MEASURES: Demographic and clinical data were collected including age, gender, risk factors, clinical manifestations, initial diagnosis, diagnostic investigations, treatment, presenting and final visual acuity and surgical interventions. RESULTS: Contact lens (CL) use was noted in 96% of unilateral and 100% of bilateral cases. The mean duration of symptoms at presentation was 21 days and the mean duration from presentation to definitive diagnosis was 14 days. Initial diagnosis was recorded as CL-related keratitis in 70.6%, viral keratitis in 15.5% and AK in 12.0%. The diagnosis was confirmed with In vivo confocal microscopy (IVCM) in 67.2%, corneal scrape in 22.4%, corneal biopsy in 1.7% and clinically in 8.6%. IVCM sensitivity was 83.0%. Surgical intervention was required in four patients, all with delayed diagnosis (range 63-125 days). The incidence of AK has more than doubled when compared with the preceding 7-year period. CONCLUSIONS AND RELEVANCE: AK is a rare vision-threatening protozoal infection with rapidly-increasing incidence in New Zealand, predominantly affecting CL users. Diagnosis is often challenging and when delayed is associated with worse outcomes. IVCM offers rapid diagnosis with high sensitivity.