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.

Assessment of Health Disparities and Barriers to Accessing Keratoconus and Crosslinking at a Tertiary Referral Center.

PURPOSE: The aim of this study was to determine the barriers to accessing the crosslinking service in Auckland, New Zealand. METHODS: This was a prospective 1-year study of patients at Auckland District Health Board. Studied parameters included age, sex, body mass index, ethnicity, New Zealand Deprivation (NZDep; an area-based measure of socioeconomic status, 1 = low deprivation-10 = high deprivation) score of residence, disease severity (maximum keratometry and thinnest corneal thickness), attendance, distance travelled, car ownership, employment status, and visual outcomes. Statistical analysis was performed using independent t tests, Pearson correlation, independent samples ANOVA, MANCOVA, and binomial logistic regression. RESULTS: Four hundred fifty-four patients with keratoconus were analyzed and had a mean age of 24.1 ± 0.8 years, mean body mass index of 33.0 ± 9.7 kg/m 2 , and 43% were female. Pacific Peoples consisted 40.2% of the population; Maori 27.2%; Europeans 21.2%; Asian 9.9%; and Middle Eastern, Latin American, and African (MELAA) 1.3%. The mean distance travelled was 12.5 ± 9.5 km, NZDep score was 6.8 ± 2.6, and attendance was 69.0 ± 42.5%. The lowest attendance was observed in Pacific Peoples (58.9%) and the highest was in Asians (90%) ( P = 0.019). The mean worst-eye visual acuity at attendance was 0.75 ± 0.47 logMAR (6/35). Unemployment was associated with worse best-eye visual acuity at FSA ( P = 0.01) and follow-up ( P < 0.05). Maori and Pacific Peoples had the highest NZDep ( P < 0.001), were younger at presentation ( P = 0.019), had higher disease severity ( P < 0.001), and worse visual acuity ( P < 0.001). CONCLUSIONS: Poor attendance was seen in this cohort. Pacific Peoples and Maori presented younger with worse disease severity and visual acuity but also had the highest nonattendance. These results suggest that deprivation, factors associated with ethnicity, and unemployment are potential barriers to attendance.

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.

Comparing Repeatability and Agreement between Commonly Used Corneal Imaging Devices in Keratoconus.

SIGNIFICANCE: Keratometry and pachymetry are important for diagnosis and monitoring of keratoconus. Many corneal imaging units exist, but comparison to determine repeatability and agreement is paramount for adequate keratoconus management in primary and secondary care. PURPOSE: This study aimed to evaluate the repeatability and agreement of a Placido disc-based videokeratoscope (Melbourne, Victoria, Australia) used in primary care with spectral-domain optical coherence tomography (Optopol Technology, Zawiercie, Poland) and Scheimpflug corneal tomography (Oculus, Wetzlar, Germany) in secondary care. METHODS: This was a prospective single-center study where one eye was randomized to have central corneal thickness;thinnest corneal thickness (TCT); and maximum, mean, steep, and flat keratometry (Kmax, Kmean, Ksteep, and Kflat, respectively), measured with all three devices. Three measurements were completed per device to assess intraobserver repeatability. RESULTS: A total of 110 eyes from 110 patients with keratoconus were analyzed. Repeatability was best with the Pentacam for central corneal thickness, Kmax, Kmean, Ksteep, and Kflat parameters (precision, 9.21, 0.8, 0.38, 0.52, and 0.58). The Medmont had better repeatability than the Revo with Kmax, Kmean, Ksteep, and Kflat (precision, 1.41,1.35,1.43, and 1.59). Revo had the best repeatability with TCT (precision, 3.81). The intraclass correlation coefficient was >0.94 for all parameters in all devices. Agreement was generally poor between devices. However, there was good agreement between Pentacam and Medmont Kflat measurements ( P > .05). CONCLUSIONS: Repeatability of keratometry parameters with the Pentacam and Medmont was greater than the Revo, suggesting a lower threshold for detecting change in anterior corneal parameters. The Revo had the greatest repeatability for TCT, suggesting a lower threshold for detecting thinning in disease progression and corneal-crosslinking safety. There was poor agreement between devices, and it is not recommended for them to be used interchangably.

Ocular Antibiotic Utilisation across Aotearoa/New Zealand.

Ocular antibiotics are integral to the prevention and treatment of bacterial ocular infections. This study aimed to describe their utilisation across New Zealand according to patient and healthcare factors. Every subsidy-eligible community dispensing of ocular chloramphenicol, fusidic acid and ciprofloxacin in New Zealand, between 2010 and 2019, was included in this analysis. Number of dispensings/1000 population/year was quantified, stratified by patient age and urban/non-urban health districts. Dispensing rates by ethnicity were determined and were age adjusted. The proportion of dispensings by socioeconomic deprivation quintile was also determined. Chloramphenicol was the most commonly dispensed antibiotic; however, its utilisation decreased over time. Ciprofloxacin use was higher in children, while chloramphenicol use was higher in older patients. Ciprofloxacin usage was higher among Maori and Pasifika ethnicities, while fusidic acid use was lower. Chloramphenicol usage was higher among Pasifika. Antibiotic utilisation was higher in urban health districts, and in the most deprived quintile; both were most marked with ciprofloxacin. The utilisation of publicly funded ocular antibiotics across New Zealand varied between patient subgroups. These findings will help improve the prevention, management and outcomes of bacterial ocular infections, and support wider initiatives in antibiotic stewardship and medicine access equity.

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.

Effect of oral vitamin D supplementation on dry eye disease patients with vitamin D deficiency.

CLINICAL RELEVANCE: Dry eye disease (DED) and vitamin D deficiency are both common clinical entities. Vitamin D has been reported to play a significant role in ocular surface homeostasis. BACKGROUND: This study aimed to determine the therapeutic effect of oral vitamin D supplementation in dry eye disease patients with vitamin D deficiency. METHODS: A randomized, controlled study was completed in 100 patients with dry eye disease and concurrent vitamin D deficiency (< 20 ng/ml). Participants were randomly allocated to 8 weeks of oral vitamin D supplementation with both groups receiving conventional dry eye treatment with artificial tears. Schirmer's, tear break-up time (TBUT) and osmolarity tests were measured before and after eight weeks of treatment. RESULTS: The mean age of participants was 36.8 ± 8.56 years in the treatment group (n: 50) and 34.8 ± 10.13 year in the control group (n: 50). After eight weeks of treatment the mean differences in Schirmer's, TBUT and tear osmolarity were 2.38 ± 1.55 mm, 3.95 ± 1.48 s and -16.9 ± 6.28 mOsm/L, respectively in the treatment group, and 0.7 ± 0.86 mm, 0.92 ± 1.57s and -3.34 ± 2.0 mOsm/L respectively in the control group (p < 0.001 for all parameters). The treatment group demonstrated a more significant improvement than the control group in Schirmer's, TBUT and osmolarity values (p < 0.001). CONCLUSION: Vitamin D supplementation as an adjuvant to routine dry eye treatment improves ocular surface hemostasis parameters, results in better tear stability and a more improved tear osmolarity in patients with vitamin D deficiency.

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.].

The Aotearoa Research Into Keratoconus Study: Geographic Distribution, Demographics, and Clinical Characteristics of Keratoconus in New Zealand.

PURPOSE: To investigate the epidemiologic, demographic, and basic clinical characteristics of individuals with keratoconus managed by optometrists in New Zealand (NZ)/Aotearoa. METHODS: A prospective, longitudinal, nationwide, survey protocol was completed for every patient with keratoconus who underwent a consultation with participating optometrists in a 2-year period. Data for each patient included date of birth, sex, self-reported ethnicity, new or previous diagnosis, uncorrected (UCVA) and best-corrected visual acuity (BCVA), type of refractive correction required to obtain BCVA and keratometric readings obtained using keratometry or computerized topography. RESULTS: One thousand eight hundred sixty-nine cases were identified, with a mean age of 41.0 ± 15.7 years, 56.4% being men, and 87.3% with previous diagnosis. The distribution of cases was skewed toward Auckland (41.6%), Waikato (21.3%), Wellington (16.8%), and Bay of Plenty (13.3%). Self-reported ethnicities were predominantly NZ European (54.4%), Maori (24.7%), and Pacific Peoples (15.5%), disproportionate to the general population profile (74.0%, 14.9%, and 7.4% respectively). Most eyes (64.3%) were managed with rigid contact lenses (corneal lens in 34.2%). The mean K-mean was 49.0 ± 5.7 D. The mean UCVA was 6/42 and BCVA was 6/9. Maori and Pacific Peoples had both the highest K-mean and proportions of eyes graded stage IV on the Amsler-Krumeich scale. CONCLUSIONS: The results indicate that keratoconus is relatively common in NZ with at least 1869 patients managed by optometrists in 2 years. Most eyes had mild to moderate disease; however, Maori and Pacific Peoples seem to have greater disease severity. An ethnic predilection is apparent, with Maori and Pacific Peoples overrepresented relative to their population proportions, reinforcing a long-held clinical suspicion.

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.

Repeatability and Agreement of Horizontal Corneal Diameter Measurements Between Scanning-Slit Topography, Dual Rotating Scheimpflug Camera With Placido Disc Tomography, Placido Disc Topography, and Optical Coherence Tomography.

PURPOSE: The purpose of this study was to assess the repeatability and agreement of horizontal white-to-white (WTW) measurements using 4 different imaging modalities including a slit-scanning elevation topographer, dual rotating Scheimpflug camera and Placido Disc tomographer, Placido Disc topographer, and anterior segment optical coherence (OCT) tomographer. METHODS: In this prospective study, 33 eyes of 33 healthy subjects were scanned 3 times using each of the Orbscan IIz, Sirius, Nidek OPD III, and DRI OCT Triton devices and WTW measurements were recorded. Repeatability was assessed using the intraclass correlation coefficient (ICC), and agreement was analyzed using Bland-Altman plots. RESULTS: Mean WTW values obtained from the Orbscan IIz, Sirius, Nidek, and DRI OCT Triton devices were 11.76 ± 0.41, 12.10 ± 0.45, 12.14 ± 0.41, and 12.40 ± 0.48 mm, respectively. Overall, there was high repeatability, with the ICC >0.86 for all devices. The Sirius showed the highest repeatability (ICC = 0.993), and the Nidek the lowest (ICC = 0.870). All pairwise comparison showed significant differences in the mean WTW measurements ( P < 0.01) except between Sirius and Nidek ( P = 0.27). Mean differences showed that the DRI OCT Triton had the highest WTW values, followed by Nidek, Sirius, and finally by Orbscan, which provided the lowest measurements. All pairwise comparisons had wide limits of agreements (between 0.60 and 0.80 mm). CONCLUSIONS: In healthy subjects the 4 devices demonstrated high repeatability in WTW measurement. However, a poor agreement between the devices suggests that they should not be used interchangeably for WTW measurements in clinical practice.

Prospective one year study of corneal biomechanical changes following high intensity, accelerated cornea cross-linking in patients with keratoconus using a non-contact tonometer.

PURPOSE: To characterize corneal biomechanical properties utilizing a dynamic ultra-high-speed Scheimpflug camera equipped with a non-contact tonometer (CorVis ST, CST) in keratoconic corneas following continuous high intensity, high irradiance corneal cross-linking. DESIGN: Prospective longitudinal single-centre study at a tertiary referral center. METHODS: Corneal biomechanical properties were measured in patients with progressive keratoconus undergoing high intensity (30 mW/cm2), high irradiance (5.4 J/cm2), accelerated corneal cross-linking with continuous exposure to ultraviolet-A for 4 min. CST was used to assess corneal biomechanical properties pre-operatively and at 1, 3, 6 and 12 months post-operatively. CST output videos were further analyzed using several previously reported algorithms. RESULTS: A total of 25 eyes of 25 participants were examined. The mean age of participants was 20.9 ± 5.3 years; 56% were male and 80% were of Maori or Pacific Island origin. Energy absorbed area (mN mm), was the only significantly changed parameter compared to baseline at all time points measuring 3.61 ± 1.19 preoperatively, 2.81 ± 1.15 at 1 month (p = 0.037), 2.79 ± 0.81 (p = 0.033) at 3 months, 2.76 ± 0.95 (p = 0.028) at 6 months and 2.71 ± 1.18 (p = 0.016) at 12 months. CONCLUSIONS: The significant difference between the pre and post-operative energy absorbed area appears to reflect changes in corneal viscous properties that occur following corneal cross-linking.

Keratoconus detection of changes using deep learning of colour-coded maps.

OBJECTIVE: To evaluate the accuracy of convolutional neural networks technique (CNN) in detecting keratoconus using colour-coded corneal maps obtained by a Scheimpflug camera. DESIGN: Multicentre retrospective study. METHODS AND ANALYSIS: We included the images of keratoconic and healthy volunteers' eyes provided by three centres: Royal Liverpool University Hospital (Liverpool, UK), Sedaghat Eye Clinic (Mashhad, Iran) and The New Zealand National Eye Center (New Zealand). Corneal tomography scans were used to train and test CNN models, which included healthy controls. Keratoconic scans were classified according to the Amsler-Krumeich classification. Keratoconic scans from Iran were used as an independent testing set. Four maps were considered for each scan: axial map, anterior and posterior elevation map, and pachymetry map. RESULTS: A CNN model detected keratoconus versus health eyes with an accuracy of 0.9785 on the testing set, considering all four maps concatenated. Considering each map independently, the accuracy was 0.9283 for axial map, 0.9642 for thickness map, 0.9642 for the front elevation map and 0.9749 for the back elevation map. The accuracy of models in recognising between healthy controls and stage 1 was 0.90, between stages 1 and 2 was 0.9032, and between stages 2 and 3 was 0.8537 using the concatenated map. CONCLUSION: CNN provides excellent detection performance for keratoconus and accurately grades different severities of disease using the colour-coded maps obtained by the Scheimpflug camera. CNN has the potential to be further developed, validated and adopted for screening and management of keratoconus.