Maged Alnawaiseh

Accelerated (18 mW/cm²) Corneal Collagen Cross-Linking for Progressive Keratoconus.

Purpose: The aim of this study was to determine the efficacy of accelerated riboflavin–ultraviolet A–induced corneal collagen cross-linking (CXL) (irradiance of 18 mW/cm2 for 5 minutes). Methods: In this study, we retrospectively reviewed the charts and anterior segment data of patients after accelerated CXL. Visual, topographic, pachymetry, and densitometry data were extracted and analyzed before surgery and at follow-up (minimum 12 months) after treatment. Results: A total of 28 eyes of 20 patients (mean age, 28.1 ± 8.1 years) were included in this study. The mean follow-up time was 21.7 ± 7.2 months (range, 12–34 months). No statistically significant changes were found in the mean corrected distance visual acuity, corneal astigmatism, Kmean, Kflat, Ksteep, corneal pachymetry (at the apex and at the thinnest point), and corneal densitometry at follow-up. A significant reduction of Kmax, index of surface variance, index of vertical asymmetry, and Km of the posterior corneal surface (KmB) was observed (Kmax: P = 0.018; index of surface variance: P = 0.016; index of vertical asymmetry: P = 0.038; KmB: P = 0.008). No complications were reported during the postoperative follow-up period in this study. Conclusions: Based on a mean follow-up time of 21.7 months, accelerated CXL (18 mW/cm; 5 minutes) is effective in stopping the progression of keratoconus without raising any safety concerns. Improvement in Kmax and stabilization of corrected distance visual acuity were noted after treatment. However, prospective studies with longer follow-up using different accelerated CXL settings are needed to validate these findings.

Changes in Corneal Transparency After Cross-linking for Progressive Keratoconus: Long-term Follow-up.

PURPOSE To determine long-term changes in corneal transparency after riboflavin-ultraviolet A-induced corneal collagen cross-linking (CXL). METHODS Charts and anterior segment data of patients after CXL for progressive keratoconus were retrospectively reviewed. Patients were examined using the Scheimpflug-based Pentacam corneal densitometry module (Oculus Optikgeräte, Wetzlar, Germany) before CXL and at five postoperative follow-up visits: 1 to 3, 3 to 6, 6 to 12, 12 to 24, and 24 to 36 months. RESULTS Forty-two eyes of 28 patients (mean age: 27.9 ± 8.6 years) were included. Total corneal light backscatter was higher 1 to 3 months after CXL than before CXL (P < .001). There were significant differences, especially in the anterior (P < .001) and central (P < .001) layer at total diameter and posterior layer (P = .014) and the three central annuli at total corneal thickness (0 to 2 mm: P < .001; 2 to 6 mm: P < .001; 6 to 10 mm: P = .002). Total corneal light backscatter at total corneal thickness and total diameter faded over time following CXL. The backscatter was significantly lower 24 to 36 months after CXL than before CXL (P < .001). CONCLUSIONS Corneal densitometry peaks in the first months after CXL and returns to preoperative values approximately 1 year after CXL. Two years after CXL, corneal densitometry reaches values obtained for healthy, untreated corneas, thus achieving an improvement in corneal clarity over untreated keratoconic corneas.

Corneal Densitometry, Central Corneal Thickness, and Corneal Central-to-Peripheral Thickness Ratio in Patients With Fuchs Endothelial Dystrophy.

Purpose: The aim of the study was to quantify Scheimpflug corneal densitometry in patients with Fuchs endothelial dystrophy (FED). Methods: In this study, we retrospectively reviewed the charts and anterior segment data of 49 patients with FED before posterior lamellar keratoplasty and 51 healthy controls. The patients were examined using the Scheimpflug-based Oculus Pentacam. Central corneal thickness (CCT), ring-averaged (on a circle of 2, 2.4–10 mm diameter) noncentral corneal thickness, and densitometry data in different corneal layers and in different annuli were extracted and analyzed. Results: The total corneal light backscatter at total corneal thickness (CT) and at total diameter was significantly higher in the FED group when compared with the control group (FED group: 28.8 ± 6.7; control group: 24.3 ± 4.1; P < 0.001). When the corneal surface was divided into concentric annular zones at total CT, the differences were significant only in the 2 central annuli (P < 0.001). The total corneal light backscatter at total CT in the central 0–2 mm annulus correlated moderately with the central corneal thickness (Pearsons correlation = 0.55, P < 0.001). Conclusions: Corneal light backscatter in the central cornea was greater in patients with FED than in normal subjects. Corneal densitometry enables us to evaluate the optical quality of the cornea in different corneal layers and in different annuli. It is a useful, objective method that, in combination with central corneal thickness and corneal central-to-peripheral thickness ratio, can help to quantify FED severity.

Changes in Corneal Densitometry in Patients with Fuchs Endothelial Dystrophy after Endothelial Keratoplasty

ABSTRACT Purpose: The aim of the study was to quantify corneal densitometry in patients with Fuchs endothelial dystrophy (FED) after endothelial keratoplasty. Materials and methods: We retrospectively reviewed the charts and anterior segment data of patients with FED before and after endothelial keratoplasty. Patients were examined using the Scheimpflug-based Oculus Pentacam corneal densitometry module. Densitometry parameters in different corneal layers and in different annuli were extracted and analyzed. Results: 27 eyes of 27 patients after endothelial keratoplasty (11 DSAEK, 16 DMEK) were included. After endothelial keratoplasty the total corneal light backscatter at total corneal thickness in the central cornea (0–2 mm annulus) was significantly lower than before (DSAEK: p = 0.026, DMEK: p = 0.001). In the entire group the total corneal light backscatter at total corneal thickness and at total diameter before surgery correlated with the postoperative values (Pearson correlation = 0.49, p = 0.01). The strongest correlation was found in the central layer in the DMEK group (Pearson correlation = 0.79, p < 0.001). Conclusions: Corneal densitometry is a useful, objective method for quantification of the outcome of posterior lamellar keratoplasty irrespective of visual acuity. There is a significant correlation between preoperative and postoperative corneal light backscatter values after endothelial keratoplasty, especially in the case of the DMEK procedure.

Changes in Corneal Refractive Power for Patients With Fuchs Endothelial Dystrophy After DMEK.

Purpose: To quantify changes in the refractive power of the anterior and posterior corneal surfaces after Descemet membrane endothelial keratoplasty (DMEK) so as to optimize the accuracy of intraocular lens (IOL) power calculations. Methods: This study included 28 eyes of 21 patients (age 66.6 ± 9.4 years, 11 female, 10 male). Scheimpflug-based Oculus Pentacam imaging was performed before and after DMEK surgery for Fuchs endothelial dystrophy. Corneal power was measured using the K-value of simulated keratometry (SimK) of Pentacam and total corneal refractive power (TCRP) in corneal zones from 1 to 8 mm (SimK 1-8, TCRP1-8). We also analyzed changes in the keratometric power deviation (KPD) and pachymetry. Results: Changes in the SimK in the central cornea were minimal and not significant (SimK 3: before = 43.24 ± 1.33 D; after = 43.01 ± 1.37 D; P = 0.101) but they decreased significantly in the corneal periphery (SimK 4: P = 0.021; SimK 5: P = 0.004; SimK 6: P = 0.002; SimK 7: P = 0.002; SimK 8: P = 0.008). Postoperative TCRP in the central cornea decreased significantly compared with preoperative values (TCRP 3: before = 43.05 ± 1.44 D; after = 41.94 ± 1.34 D; P < 0.001); [TCRP 4: before = 43.16 ± 1.40 (D); after = 41.99 ± 1.27 (D); P < 0.001]. The keratometric power deviation increased significantly after DMEK (before = 0.74 ± 0.45 D; after = 1.40 ± 0.26 D; P < 0.001). Conclusions: DMEK surgery induced a significant change in the refractive power of the posterior surface of the cornea and thus a decrease in the TCRP of about 1 D, whereas the SimK, which measures only the anterior cornea, remained nearly unchanged. To avoid a hyperopic surprise, it is essential that this TCRP decrease is not overlooked in intraocular lens power calculations.

Optical coherence tomography (OCT) angiography findings in retinal arterial macroaneurysms

BackgroundOptical coherence tomography angiography is a novel imaging technique that allows dyeless in vivo visualization of the retinal and choroidal vasculature. The purpose of this study was to describe optical coherence tomography (OCT) angiography findings in patients with retinal arterial macroaneurysms (RAMs).MethodsThree eyes of three patients with RAMs were retrospectively included. Fundus photography, OCT, fluorescein angiography (FA), and OCT angiography were performed. The entire imaging data was analyzed in detail.ResultsOCT angiography could detect the RAMs noninvasively without dye injection. By simultaneously observing the OCT scans, it was possible to determine the depth of the RAMs in the retina, to detect the exact localization in relation to the main vessel, and to determine the level of blood flow in the RAMs.ConclusionsOCT angiography can clearly visualize RAMs without use of a dye. It also allows layer-specific observation of blood flow in each layer of the RAM. OCT angiography provides additional dynamic information on RAMs, which is not obtained with FA and facilitates a better understanding of its morphology and activity. This information in combination with ICG and fluorescein angiography can help to optimize direct laser treatment.

SHORT-TERM EFFECTS OF EXERCISE ON OPTIC NERVE AND MACULAR PERFUSION MEASURED BY OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY

Purpose: To evaluate the effects of exercise on optic nerve and macular perfusion using optical coherence tomography angiography. Methods: Thirteen eyes of 13 healthy volunteers were examined using a high-speed and high-resolution spectral-domain optical coherence tomography XR Avanti with a split-spectrum amplitude-decorrelation angiography algorithm. Blood pressure, heart rate, the mean area of the foveal avascular zone , and flow density on the optic nerve head and macula, before and after exercise were measured and analyzed. Results: Mean patient age was 27.3 ± 3.5 years. Heart rate, systolic and diastolic blood pressure increased significantly after exercise (P < 0.001). The mean area of the foveal avascular zone did not change significantly after exercise (before: 0.27 ± 0.07 mm2; after: 0.26 ± 0.07 mm2; P = 0.10). The peripapillary and the parafoveal flow density decreased significantly after exercise (peripapillary: before: 65.1 ± 2.1; after: 62.3 ± 3.0; P < 0.001 and parafoveal: before: 56.7 ± 1.3; after: 55.6 ± 1.5; P = 0.007). Conclusion: Increased physical activity induced significant changes in optic nerve and macular perfusion, which were measured using split-spectrum amplitude-decorrelation angiography optical coherence tomography angiography. In studies that aim to evaluate optic nerve and macular perfusion using optical coherence tomography angiography, it should be strongly recommended that patients rest before imaging is performed and that data concerning systemic circulation including blood pressure and pulse is included within the evaluation.

Accuracy of Measurements With the iCare HOME Rebound Tonometer.

Purpose:To evaluate the accuracy of intraocular pressure (IOP) measurements obtained with the newly available iCare HOME (RTHOME) rebound tonometer compared with the iCare ONE (RTONE) tonometer and Goldmann applanation tonometry (GAT), and possible correlation with central corneal thickness (CCT). Materials and Methods:IOP measurements were obtained from 154 patients by an ophthalmologist (doc) using each of the above-mentioned tonometers. In addition, patients (pat) measured their own IOP with the RTHOME and RTONE. The means and SD of results obtained with the different tonometers were compared. Agreement between the tonometers was calculated using the Bland-Altman method. Results:Mean IOPs for the right eyes only were 15.9±6.4 mm Hg (RTONEdoc), 15.8±6.4 mm Hg (RTONEpat), 15.0±5.9 mm Hg (RTHOMEdoc), 14.9±6.3 mm Hg (RTHOMEpat), and 15.8±4.4 mm Hg (GAT). Bland-Altman analysis revealed mean differences (bias) between RTONEdoc and RTHOMEdoc, between RTHOMEdoc and RTHOMEpat, and between RTHOMEdoc and GAT of 0.8, 0.1, and −0.8 mm Hg, respectively, with 95% limits of agreement of −3.5 to 5.2, −4.9 to 5.1, and −7.2 to 5.6 mm Hg, respectively. Linear regression of the comparisons revealed a proportional error over the range of pressures examined in the case of RTHOMEdoc versus GAT (slope=0.32, P<0.001). Considering the data from all eyes, the difference between RTHOMEdoc and GAT correlated significantly with the CCT (P=0.01). Conclusion:RTHOME readings correlate well with the GAT results although some limitations such as dependency of readings on CCT and increasing differences at lower and higher IOP levels need to be taken into account.

Comparison of Choriocapillaris Flow Measurements between Two Optical Coherence Tomography Angiography Devices

Purpose: To evaluate choriocapillaris (CC) perfusion in healthy subjects using 2 different optical coherence tomography angiography (OCT-A) devices. Procedures: Macular OCT-A imaging (36 eyes of 36 subjects) was performed using Optovue AngioVue and Zeiss AngioPlex devices. CC decorrelation signal index was assessed, and CC data were analyzed regarding intra-device variability, inter-device correlation, age, signal strength, and fields of view. Results: The intra-device variability of CC measurements in the 3 × 3 mm2 field was 5.3 and 2.6% (Angiovue and Angioplex, coefficients of variation; 6 × 6 mm2: 8.0 and 2.8%, respectively). Mean CC decorrelation signal index in 3 × 3 mm2 was 104.3 ± 6.7 (Angiovue) and 81.3 ± 9.2 (Angioplex) (6 × 6 mm2: 95.6 ± 8.1, 81.1 ± 6.5) with high correlation between both devices (3 × 3 mm2: p = 0.0053; 6 × 6 mm2: p = 0.0139). CC decorrelation signal index in 3 × 3 mm2 was significantly higher in subjects aged ≤58 years compared to subjects aged ≥59 years (Angiovue: 107.3 ± 3.6, 101.3 ± 7.7, p = 0.0156; Angioplex: 84.6 ± 7.6, 78.0 ± 9.5, p = 0.0371). Signal strength was 64.6 ± 8.9 (Angiovue) and 9.5 ± 0.8 (Angioplex). Conclusion: Both devices showed low intra-device variability and a high inter-device correlation. CC decorrelation signal index was negatively correlated with advancing age.

OCT-Angiography reveals reduced vessel density in the deep retinal plexus of CADASIL patients

Optical coherence tomography angiography (OCT-A) represents the most recent tool in ophthalmic imaging. It allows for a non-invasive, depth-selective and quantitative visualization of blood flow in central retinal vessels and it has an enormous diagnostic potential not only in ophthalmology but also with regards to neurologic and systemic diseases. Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a hereditary vascular small-vessel disease caused by Notch3 mutations and represents the most common form of hereditary stroke disorder. In this study, CADASIL patients prospectively underwent OCT-A imaging to evaluate retinal and choriocapillaris blood flow as well as blood flow at the optic nerve head. The vessel density of the macular region and the size of the foveal avascular zone in the superficial and deep retinal plexus were determined as well as the vessel density at the optic nerve head and in the choriocapillaris. Additionally, cerebral magnetic resonance images were evaluated. The main finding was that vessel density of the deep retinal plexus was significantly decreased in CADASIL patients compared to healthy controls which may reflect pericyte dysfunction in retinal capillaries.