Total Corneal Research Articles

Effects of atropine 0.01% on refractive errors in children with myopia

BackgroundLittle is known about changes in astigmatism during atropine treatment. We aimed to explore the effects of atropine 0.01% eye drops on both spherical and cylindrical refractive errors in myopic children. MethodsChildren aged 6–14 years with myopia ≥ −6.00 D and < −0.50 D, and total astigmatism > −2.00 D in at least one eye were enrolled. Subjects were randomised either to receive atropine 0.01% once nightly with single-vision lenses or simply to wear single-vision lenses and were followed up at 3-month intervals. Cycloplegic refraction and axial length were measured. The magnitude and direction of total astigmatism (TA), corneal astigmatism (CA), and residual astigmatism (RA) were evaluated. ResultsOverall, 119 eyes (69 eyes in the atropine group and 50 eyes in the control group) were included in the final analyses after 9 months. Atropine-treated eyes showed significantly less progression of myopia than did control eyes (spherical equivalent: −0.35 ± 0.33 vs. −0.56 ± 0.49 D, p = 0.001; axial length: 0.20 ± 0.19 vs. 0.33 ± 0.19 mm, p < 0.001). Compared with control eyes (−0.04 ± 0.23 D), a significant increase in TA was observed in the atropine-treated eyes (−0.14 ± 0.29 D); this was mainly attributed to the increase in CA (−0.17 ± 0.26 D) rather than the minor decrease in RA (0.02 ± 0.32 D). ConclusionsAtropine 0.01% was effective in preventing myopia progression, whereas 9 months of atropine treatment resulted in a clinically small, but statistically significant increase in TA in myopic Chinese children.

Comparison of total corneal power measurements obtained with different devices after myopic keratorefractive surgery.

To analyze the differences, agreements, and correlation among total corneal power parameters generated by different instruments after myopic keratorefractive surgery. The prospective cross-sectional study included patients who underwent myopic keratorefractive surgery and received measurements of corneal power 3mo after surgery. Automated keratometer was used for the measurement of simulated keratometry (SimK), swept-source optical coherence tomography (SS-OCT) based biometer for total keratometry (TK), anterior segment-OCT for real keratometry (RK), and Scheimpflug keratometer for the true net power (TNP), the total corneal refractive power (TCRP) and equivalent K-readings (EKR). The differences among these parameters were analyzed, and the agreements and correlation between SimK and other total corneal power parameters were investigated. A total of 70 eyes of 70 patients after myopic keratorefractive surgery were included. The evaluated corneal power parameters were as follows: SimK 38.32±1.93 D, TK 37.54±2.12 D, RK 36.64±2.09 D, TNP 36.56±1.97 D, TCRP 36.70±2.01 D, and EKR 37.55±2.00 D. Pairwise comparison showed that there were significant differences (P<0.001) among all parameters except for between TK and EKR, RK and TNP, RK and TCRP (P=1.000, 1.000, 1.000, respectively). The limits of agreement between SimK and TK, RK, TNP, TCPR, and EKR were 1.08, 1.08, 1.43, 1.48, and 1.73 D, respectively. All parameters showed good correlation with SimK, and the correlation coefficients were 0.995, 0.994, 0.983, 0.982, and 0.975. Among the corneal power parameters after myopic keratorefractive surgery, the value of SimK is the largest, followed by TK and EKR, with TCRP, RK, and TNP being the smallest. The differences among the parameters may be attributable to the different calculation principles. Correct understanding and evaluation of corneal power parameters can provide a theoretical basis for taking advantage of the total corneal power to improve the accuracy of intraocular lens calculation after keratorefractive surgery.

Evaluation of the Effect of Scleral Buckling on Anterior Segment and Refractive Changes Using Anterior Segment Optical Coherence Tomography

ABSTRACT Purpose To evaluate the changes of anterior segment and refractive parameters after scleral buckling (SB) surgery for uncomplicated rhegmatogenous retinal detachment (RRD) using anterior segment optical coherence tomography (AS-OCT). Methods Thirty-six RRD eyes were consecutively enrolled. Analysis concerned the central corneal thickness (CCT), anterior chamber depth (ACD), anterior chamber volume (ACV), iris-trabecular contact (ITC), angel opening distance (AOD), angle recess area (ARA), trabecular-iris space area (TISA)，trabecular iris angle (TIA) and refractive parameters, including average keratometry (AvgK), cylindrical power (CYL), regular astigmatism, asymmetry and high order irregularity (HOI) at baseline and 1 day, 1 month, 2 months, 6 months and 12 months postoperatively. AS-OCT was performed at RRD diagnosis and day 1, week 1, month 1 and month 6 after SB to evaluate the scleral buckling. Results A statistically significant postoperative CCT increase, ACD and ACV decrease were observed at 1 day and 1 month postoperatively. ITC analysis showed that the angle of the entire circumference narrowed at 1 month postoperatively. There was a significant decrease in all the angle parameters (AOD500/750, ARA500/750, TISA500/750, and ARA500/750) at 1 day and 1 month after SB surgery. However, all of the above parameters returned to the preoperative level at 12 months. Refractive parameters including AvgK, regular astigmatism, CYL, asymmetry, and HOI of anterior corneal surface and total corneal increased on the 1 day and 1 month after SB surgery and persisted even after 12 months follow-up. However, there was no significant difference in refractive parameters of posterior corneal surface during follow-up. Conclusion The changes in the structure of anterior segments after SB surgery were almost returned to the preoperative levels at 12 months postoperatively. However, SB surgery has a long-term effect on refractive parameters throughout a 12-month follow-up.

Comparison of corneal power assessment methods after small incision lenticule extraction

Objective: To compare the accuracy of different corneal curvature parameters in assessing the corneal refractive status and tracking corneal power changes after small incision lenticule extraction (SMILE). Methods: This prospective cross-sectional study tracked and recorded total corneal curvature parameters measured by different instruments before and three months after SMILE for myopia. These parameters, including total keratometry (TK) from the IOLMaster 700, total corneal refractive power (TCRP) from the Pentacam AXL, real keratometry (RK) from the CASIA 2, and corrected parameters calculated using the Haigis, Shammas, and Maloney methods, were compared with data obtained using the clinical history method (CHM). Surgically induced changes in TK, TCRP, and RK were analyzed and compared with those in spherical equivalent on the corneal plane (ΔSEco). Results: The study included 40 eyes (40 participants). After SMILE, the difference was smallest between TK [(0.08±0.38) D] and CHM values (P>0.05). However, TCRP, RK, KHaigis, KShammas, and KMaloney were significantly different from CHM data (P<0.05). The width of the 95% limits of agreement of TK (1.49 D) was narrowest, followed by that of RK (1.57 D). Pearson analysis showed that each parameter had a good correlation with CHM data. The differences between the changes in TK, TCRP and RK caused by surgery and ΔSEco were (0.03±0.39) D, (0.17±0.43) D, and (-0.19±0.46) D, respectively. The width of the 95% limits of agreement of ΔTK (1.54 D) was narrowest, and the correlation coefficient of ΔTK (0.951) was highest. Conclusion: The parameter TK of the IOLMaster 700 can provide accurate and objective corneal power evaluation after SMILE.

Prediction of total corneal power in keratoconus using anterior surface data

ABSTRACT Clinical relevance Keratoconus results in an increase in anterior and posterior curvatures and a reduction in corneal thickness. Anterior corneal ectasia is partially compensated by remodelling the corneal epithelium. Therefore, there is an alteration in the relationship between corneal surfaces and variation in corneal power. The variation in corneal power is one of the sources that induces errors in IOL power calculation. Background This study aimed to assess a method for predicting total corneal power in keratoconus using several anterior surface parameters at 3 mm and 4 mm. Methods Tomographic data obtained using Pentacam (Oculus, Germany) were analysed from 280 eyes of 140 patients with keratoconus using anterior and posterior keratometry, anterior Q-value at 8 mm, central corneal thickness, Kmax location and value, and true net power at 4 mm (TNP). Calculated total corneal power (TCPc) at 3 mm was obtained using the Gauss formula. Predicted total corneal power at 3 mm (TCPp3) and 4 mm (TCPp4) was obtained from univariate (TCPp3u and TCPp4u) and multivariate linear regression formulae (TCPp3m and TCPp4m). SimK, anterior Q-value, vertical location, and Kmax value were used in the multivariate formulae. Mean absolute error (MAE) and median absolute error (MedAE) were also calculated. Absolute frequencies within dioptric ranges of all formulas divided for keratoconus grading were evaluated. Results TCPc and TNP exhibited a good correlation (R2 = 0.58, p < 0.05) with a higher dispersion above 50 D of corneal power. Highly significant correlations were observed between TCPp3u and TCPc (R2 = 0.978, p < 0.05) and TCPp3m and TCPc (R2 = 0.989, p < 0.05). Lower but significant correlations were observed between TCPp4u and TNP (R2 = 0.692, p < 0.05) and between TCPp4m and TNP (R2 = 0.887, p < 0.05). The best results for TCP prediction at 3 and 4 mm were obtained with TCPp3m and TCPp4m as follows: MAE of TCPp3m was 0.24 ± 0.20 (SD) D with MedAE of 0.20 D, while MAE of TCPp4m was 0.96 ± 0.77 D with MedAE of 0.80 D. The 3 mm multivariate regression formula results in higher absolute frequencies of prediction errors in the total eyes within 0.5 D (93%) than the univariate formula (81%). At 4mm, the multivariate regression formula has a lower percentage within 0.5 D (32%) than the univariate formula (41%), but the percentage of the multivariate formula is higher within 1 D (63%) than the univariate formula (56%). Conclusion All formulas show a decrease in accuracy with increasing grades of keratoconus. Multivariate linear regression formulae using only anterior surface data can predict TCP with good approximation in eyes with keratoconus in cases where posterior surface parameters are unavailable. The vertical location of Kmax and the anterior asphericity could play a relevant role in the prediction of total corneal power in keratoconus.

Comparison of Corneal Power Difference Maps with Achieved Myopic Correction Using Scheimpflug Tomography After LASIK, PRK, and SMILE.

To compare corneal power difference maps (∆maps) obtained from the Pentacam in patients with 1 year follow-up after LASIK, PRK, and SMILE with further stratification to low, moderate, and high myopia. This retrospective study was comprised of patients who had preoperative and 1-year postoperative power maps that were obtained-front sagittal (SagF), refractive power (RP), true net power (TNP), and total corneal refractive power (TCRP)-for evaluation. Measurements were recorded and compared at the 4mm, 5mm and 6mm pupil and apex zones. Comparisons were made between each specific power ∆map and the surgically induced refractive change (SIRC). Further analysis of the ∆maps was performed based on degree of myopia (high, moderate, and low). Correlation and agreement were also assessed with regression and limits of agreement (LoA). There were 172 eyes in the LASIK group, 187 eyes in the PRK group, and 46 eyes in the SMILE group. In the LASIK group, TNP ∆map at 5mm pupil zone had the least absolute mean difference with SIRC (0.007 ± 0.42D). In the PRK group, TNP ∆map at 5mm apex zone was most accurate compared to SIRC (0.066 ± 0.45D). In the SMILE group, TCRP ∆map at 4mm apex zone had the closest absolute value when compared to SIRC (0.011 ± 0.50D). There was good correlation and agreement for all three surgery groups, LASIK: r = 0.975, LoA -0.83D to +0.83D, PRK: r = 0.96, LoA -0.83D and +0.95D, and SMILE: r = 0.922, LoA -0.97 D to +0.99D. TNP ∆maps most accurately measured corneal power in the LASIK and PRK groups while TCRP ∆maps were most accurate in the SMILE group. The degree of myopia may change which ∆map is most accurate.

Transcutaneous Electrical Stimulation for the Prevention of Dry Eye Disease after Photorefractive Keratectomy: Randomized Controlled Trial.

To evaluate the efficacy and safety of transcutaneous electrical stimulation (TES) for the prevention of dry eye after photorefractive keratectomy (PRK). Prospective, single-center, single-blinded, parallel group, placebo-controlled, randomized clinical trial. Between February 2020 and October 2020, patients at the Samsung Medical Center scheduled to undergo PRK to correct myopia were screened and enrolled. The participants in the TES group were instructed to use the electrical stimulation device (Nu Eyne 01, Nu Eyne Co) at the periocular region after the operation, whereas those in the control group were to use the sham device. Dry eye symptoms were evaluated preoperatively and postoperatively at weeks 1, 4, and 12 using the Ocular Surface Disease Index (OSDI) questionnaire, the 5-Item Dry Eye Questionnaire (DEQ-5), and the Standard Patient Evaluation for Eye Dryness II (SPEED II) questionnaire. Dry eye signs were assessed using tear break-up time (TBUT), total corneal fluorescein staining (tCFS), and total conjunctival staining score according to the National Eye Institute/Industry scale. The pain intensity was evaluated using a visual analog scale. Primary outcomes were OSDI and TBUT. Twenty-four patients were enrolled and completed follow-up until the end of the study (12 patients in the TES group, 12 patients in the control group). Refractive outcomes and visual acuity were not different between the groups. No serious adverse event was reported with regard to device use. No significant difference in OSDI and SPEED II questionnaires and the DEQ-5 was observed between the groups in the 12th week after surgery. The TBUT scores 12 weeks after the surgery were 9.28 ± 6.90 seconds in the TES group and 5.98 ± 2.55 seconds in the control group with significant difference (P= 0.042). The tCFS and total conjunctival staining score were significantly lower in the TES group than in the control group at postoperative 4 weeks. Pain intensity at the first week was significantly lower in the TES group than in the control group by 65% (P= 0.011). The application of TES is safe and effective in improving dry eye disease after PRK. The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Precision of Corneal Aberrations Measured by a New SD-OCT/Placido Topographer and Its Agreement With a Scheimpflug/Placido Topographer.

To evaluate the precision of corneal aberrations measured by a new SD-OCT/Placido topographer, the MS-39 (CSO), and to compare them with those provided by a Scheimpflug/Placido device, the Sirius (CSO), in normal eyes. This study enrolled 90 normal eyes of 90 patients. Total root mean square (RMS), higher order RMS, coma, trefoil, spherical aberration, and astigmatism II were analyzed. The within-subject standard deviation (Sw), test-retest repeatability, and intraclass correlation coefficient (ICC) were calculated to assess the precision. Bland-Altman plots and 95% limits of agreement (LoAs) were calculated to assess the agreement. For intraobserver repeatability of anterior and total corneal aberrations, most of the ICCs were greater than 0.869, except for trefoil and astigmatism II. Regarding the posterior corneal surface, the ICCs of total RMS, coma, and spherical aberration were higher than 0.878, whereas the ICCs of higher order RMS, trefoil, and astigmatism II were lower than 0.626. All test-retest repeatability values were 0.17 µm or less. In terms of interobserver reproducibility, the Sw values were 0.04 µm or less, Test-retest repeatability values were less than 0.11 µm, and all ICCs ranged from 0.532 to 0.996. Regarding agreement, 95% LoAs were small for all Zernike coefficients, and the mean difference was close to zero. The new SD-OCT/Placido device exhibited excellent repeatability and reproducibility for anterior and total surface, whereas total RMS, coma, and spherical aberrations showed high precision on the posterior surface. High agreement was confirmed between the SD-OCT/Placido and Scheimpflug/Placido devices. [J Refract Surg. 2023;39(6):405-412.].

Descemet Membrane Endothelial Keratoplasty (DMEK) Reduces the Corneal Epithelial Thickness in Fuchs' Patients.

Fuchs' endothelial corneal dystrophy (FECD) is the occurrence of corneal edema due to endothelial cell dystrophy. Descemet membrane endothelial keratoplasty (DMEK) is considered to be the gold standard of treatment. The aim of this study was to investigate the changes in the corneal epithelial thickness of FECD patients before and after DMEK and to compare these results with a healthy control cohort. In this retrospective analysis, 38 eyes of patients with FECD that were treated with DMEK and 35 healthy control eyes received anterior segment optical coherence tomography (OCT; Optovue, XR-Avanti, Fremont, CA, USA). The corneal epithelial thicknesses in different locations were analyzed and compared between the preoperative, postoperative, and control cohorts. The median follow-up time was 9 months. There was a significant degression of the mean epithelial thickness after DMEK in the central, paracentral, and mid-peripheral zones (p < 0.01) of the cornea. The total corneal thickness and stromal thickness decreased significantly as well. No significant differences were observed between the postoperative and control cohorts. In conclusion, the FECD patients had an increased epithelial thickness compared to the healthy controls, which decreased significantly after DMEK and reached thickness levels comparable to those of healthy control eyes. This study emphasized the importance of distinguishing between the corneal layers in anterior segment pathologies and surgical procedures. Moreover, it accentuated the fact that the structural alterations in FECD extend beyond the corneal stroma.

Factors influencing axial elongation in myopic children using overnight orthokeratology

Several factors influence axial length in children with myopia treated using overnight orthokeratology. To identify these factors, this retrospective study collected axial length and corneal aberration data on 78 eyes before and 1-year after orthokeratology. Patients were divided according to axial elongation (cut-off, 0.25 mm/year). Baseline characteristics included age, sex, spherical equivalent refraction, pupil diameter, axial length, and orthokeratology lens type. Corneal shape effects were compared through tangential difference maps. Group differences in higher-order aberrations of a 4 mm zone were compared at baseline and 1-year following therapy. Binary logistic regression analysis was conducted to identify the variables determined for axial elongation. Significant differences between both groups included the initial age of wearing orthokeratology lenses, type of orthokeratology lens, size of central flattening area, corneal total surface C12 (1-year), corneal total surface C8 (1-year), corneal total surface spherical aberration (SA) (1-year root mean square [RMS] values), change in total corneal surface C12, and change in front and total corneal surface SA (RMS values). The age when wearing an orthokeratology lens was the most important factor influencing axial length in children with orthokeratology-treated myopia, followed by lens type and change in the C12 of the total corneal surface.

Changes in the total corneal refractive power after insertion of intrastromal rings in patients with keratoconus in short, medium and long term

Changes in the total corneal refractive power after insertion of intrastromal rings in patients with keratoconus in short, medium and long term

Influence of the Reference Center on the Calculation of Corneal Higher Order Aberrations

To evaluate the differences in corneal wavefront measurements in myopic and hyperopic eyes when calculated using three different reference centers and explore possible influencing factors for such differences. Corneal wavefront measurements were performed in myopic and hyperopic eyes using a GALILEI Placido Dual Scheimpflug Analyzer (Ziemer Ophthalmic Systems AG). Corneal higher order aberrations (HOAs), including total, vertical, and horizontal coma-like aberrations, spherical aberrations, and total corneal HOAs through a 6-mm pupil size, were calculated over three different reference center positions: pupil center, corneal vertex, and limbus to limbus. Values were then compared between the myopic and hyper-opic eyes, and correlations with kappa distance and spherical equivalent were tested. A significant decrease in the level of total corneal HOAs (-0.04 ± 0.05 and -0.12 ± 0.09), total corneal coma (-0.07 ± 0.09 and -0.18 ± 0.12), and horizontal coma (-0.07 ± 0.11 and -0.22 ± 0.11) in myopic and hyperopic eyes, respectively, was found when recalculating from pupil center to corneal vertex centration, whereas a significant increase in the same aberrations was observed from pupil center or corneal vertex to limbus to limbus. Significant correlations were found between the kappa distance and changes in total corneal HOAs, total corneal coma, and horizontal coma from the pupil center to the corneal vertex in both groups. Corneal vertex centration generated the lowest level of corneal wavefront error in both groups. The differences in corneal aberrations between the reference centers for calculation were highly correlated with the kappa distance in hyperopic eyes. [J Refract Surg. 2023;39(5):340-346.].

SS-OCT-based ocular biometry in an adult Korean population with cataract.

To evaluate the characteristics of ocular biometric parameters in adult Korean patients with cataract. Department of Ophthalmology, Seoul National University Hospital, Seoul, South Korea. Retrospective case series. Ocular biometric values of 5273 eyes of 5273 Korean patients undergoing cataract surgery measured with the IOLMaster 700 at the Seoul National University Hospital between November 2019 and December 2021 were reviewed. A total of 5273 eyes of 5273 Korean patients were analyzed. The mean ± SD age was 66.1 ± 12.8 years, and 62% were female. Overall, age and ocular biometric parameters were correlated with each other. Particularly, age showed a negative correlation with anterior chamber depth (ACD; r = -0.357), axial length (AL; r = -0.344), and posterior keratometry (PK; r = -0.054) and a positive correlation with lens thickness (LT; r = 0.484), angle α ( r = 0.194), total keratometry (TK; r = 0.137), anterior keratometry (AK; r = 0.129), and angle κ ( r = 0.071). AL showed a positive correlation with ACD ( r = 0.503) and PK ( r = 0.339) and a negative correlation with AK ( r = -0.342), TK ( r = -0.334), LT ( r = -0.288), angle α ( r = -0.220), and angle κ ( r = -0.040). With age, anterior and total corneal astigmatism changed from with-the-rule (WTR) to against-the-rule (ATR) astigmatism. Posterior corneal astigmatism was ATR regardless of age; however, the magnitude decreased with age. Age showed a significant correlation in the order of LT, ACD, and AL. With age, angle α and κ increased, and total corneal astigmatism changes from WTR to ATR, which is mainly affected by changes in anterior corneal astigmatism. AL showed a significant correlation in the order of ACD, AK, PK, and TK. These data are pertinent for improving the result after cataract surgery, especially when using premium intraocular lenses.

Comparison of anterior segment parameters of the eye between type 2 diabetic with and without diabetic retinopathy and non-diabetic.

To compare anterior segment parameters between two groups of type 2 diabetic with and without diabetic retinopathy (DR) and non-diabetic elderly subjects based on hemoglobin A1c (HbA1c) levels and status of DR. This study was conducted on 997 residents aged 60y or over in Tehran, Iran. Diabetic group had HbA1c level ≥6.4% with no other systemic problems. The non-diabetic participants had normal eye findings and no systemic diseases. K1, K2, mean K, Q-value, anterior, central, posterior, and total corneal densitometric findings, anterior chamber volume (ACV), anterior chamber depth (ACD), corneal volume (CV), and pachymetry were measured by Pentacam AXL. A total of 678 non-diabetic (39% male) and 319 diabetic (35% male) subjects with mean age of 66.31±5.23 and 67.22±4.96y were examined, respectively. No statistically significant difference was found in anterior segment parameters between non-diabetic and diabetic groups (all P>0.05). However, middle, posterior, and total corneal densitometric values were statistically different between two groups after controlling the effects of confounders (P=0.014, 0.007, and 0.042, respectively). Corneal densitometric values in all layers, ACD, and ACV were different between diabetic subjects with and without DR (all P<0.05). In the diabetic group, only corneal densitometric values had a negative relationship with fasting blood sugar (P<0.001). ACD and ACV had a negative correlation with HbA1c levels (all P<0.05, r=-0.129 and -0.146, respectively). However, the relationships were not observed after controlling the confounders (P=0.938, 0.466, respectively). Considering the higher densitometric values of the cornea and lower ACD and ACV in diabetic subjects with DR, it is suggested that the examiners should perform comprehensive retinal examinations when faced with such conditions.

Effects of topical prostaglandin therapy on corneal layers thickness in primary open-angle glaucoma patients using anterior segment optical coherence tomography.

To evaluate the effects of latanoprost, bimatoprost, and travoprost eye drops and their preservatives on each corneal layer thickness in patients with primary open-angle glaucoma (POAG). We retrospectively analyzed 79 eyes of 79 patients with POAG who were receiving prostaglandin therapy. Patients were divided into three subgroups according to monotherapy with latanoprost, bimatoprost, and travoprost during a mean of 43.14 ± 19.12months follow-up period. In addition, the central corneal epithelial thickness (CET), central corneal stromal thickness (CST), and total central corneal thickness (CCT) were measured by anterior segment optical coherence tomography (AS-OCT) at baseline and every six months after treatment initiation at each visit between 9 and 12 o'clock in the morning. Furthermore, intraocular pressure (IOP) was measured with Goldmann applanation tonometry (GAT) after AS-OCT measurements at each visit. All three groups were not significantly different in age, gender, follow-up period, and mean intraocular pressure values (p > 0.05 for all). The reduction of CCT in the latanoprost, bimatoprost, and travoprost groups was 6.53 ± 3.17, 18.59 ± 8.42, and 10.1 ± 1.13µm, respectively. The decrease in CST values was 4.65 ± 1.54, 15.84 ± 7.47, 9.69 ± 1.45µm, and CET values were 1.88 ± 1.66, 2.75 ± 0.73, 0.41 ± 0.54µm in all groups, respectively. A statistically significant thinning was observed in all corneal layers (p < 0.05) except the CST values in the latanoprost group and CET values in the travoprost group. However, no significant difference was found in the average reduction of CET, CST, and CCT values among the three groups (p > 0.05). Topical treatment with latanoprost, bimatoprost, and travoprost affects each layer of the cornea separately according to the active and protective substances contained in these eye drops. On the other hand, the thinning effect on the corneal layers was similar in these three drugs because there was no significant difference between the three groups in the total amount of thinning of the corneal layers during the follow-up period.

Early post-operative anterior segment parameters modifications induced by PreserFlo MicroShunt in primary open-angle glaucoma

PurposeThe aim this study is to determine anterior chamber parameters variations induced by PreserFlo MicroShunt implantation, in the early post-operative days.MethodsThis is a prospective observational study on 48 eyes undergoing PreserFlo MicroShunt implantation alone (n = 30) or combined with phacoemulsification (n = 18). Anterior chamber depth (ACD) and volume (ACV), central corneal thickness (CCT) and total corneal astigmatism (TCA) were evaluated pre-operatively, post-operatively at day-1 and at 1 week with the Pentacam tomography.ResultsIntraocular pressure decreased significantly from 20.9 ± 4.0 to 8.0 ± 2.8 mmHg (p < 0.0001) and to 10.8 ± 3.7 mmHg (p = 0.0001) at day-1 and week-1, respectively. TCA varied significantly from baseline (1.5 ± 1.2 D) to both day 1 follow up (2.7 ± 1.9 D, p = 0.0003) and week 1 follow up (2.2 ± 1.6 D, p = 0.02). Nevertheless, only K1 showed a transient flattening at day 1, while K2 value didn’t show any statistical variation in the early post-operative period. CCT value rose significantly at day 1 (547 ± 49 vs. 529 ± 32 µm at baseline, p = 0.04), but then returned toward pre-operative values at week 1 (537 ± 39 µm, p = 0.57). In contrast, ACD values changed insignificantly from 3.3 ± 0.9 to 3.7 ± 1.0 mm at day 1 (p = 0.21), and then stabilized at 3.4 ± 0.9 mm (p = 0.82) at week 1 follow up. ACV changed from 150.0 ± 36.2 to 159.5 ± 42.1 mm3 at day 1 (p = 0.58), and successively to 153.9 ± 37.9 mm3 at week 1 follow up (p = 0.96). The subgroup analysis in eyes undergoing standalone PreserFlo implantation didn’t show significant changes in both ACD and ACV.ConclusionPreserFlo implantation minimizes the anterior chamber modifications generated by traditional filtering surgery, inducing low and transient corneal and biometric changes only in the very early postoperative period and insignificant changes to ACD and ACV, label of its safety and minimal invasiveness.

Efficacy and Safety of a Water-Free Topical Cyclosporine, 0.1%, Solution for the Treatment of Moderate to Severe Dry Eye Disease

Dry eye disease (DED) is a common public health problem with significant impact on vision-related quality of life and well-being of patients. Medications with rapid onset of action and a good tolerability profile remain an unmet need. To assess efficacy, safety, and tolerability of a water-free cyclosporine ophthalmic solution, 0.1% (CyclASol [Novaliq GmbH]), applied twice daily in DED compared with vehicle. CyclASol for the Treatment of Signs and Symptoms of Dry Eye Disease (ESSENCE-2) was a phase 3, multicenter, randomized, double-masked, vehicle-controlled clinical study conducted from December 5, 2020, to October 8, 2021. Following a 14-day run-in period with an artificial tear administered 2 times per day, eligible participants were randomly assigned 1:1 to the treatment groups. Patients with moderate to severe DED were included in the study. Cyclosporine solution vs vehicle administered 2 times per day for 29 days. The primary end points were changes from baseline in total corneal fluorescein staining (tCFS; 0-15 National Eye Institute scale) and in dryness score (0-100 visual analog scale) at day 29. Conjunctival staining, central corneal fluorescein staining, and tCFS responders were also assessed. A total of 834 study participants were randomly assigned to cyclosporine (423 [50.7%]) or vehicle (411 [49.3%]) groups at 27 sites. Participants had a mean (SD) age of 57.1 (15.8) years, and 609 (73.0%) were female individuals. The majority of participants self-identified in the following race categories: 79 Asian (9.5 %), 108 Black (12.9%), and 635 White (76.1%). Participants treated with cyclosporine solution had greater improvement in tCFS (-4.0 grades) than the vehicle group (-3.6 grades) at day 29 (change [∆] = -0.4; 95% CI, -0.8 to 0; P = .03). The dryness score showed treatment benefits from baseline in both groups: -12.2 points for cyclosporine and -13.6 points for vehicle (∆ = 1.4; 95% CI, -1.8 to 4.6; P = .38). In the cyclosporine group, 293 participants (71.6%) achieved clinically meaningful reductions of 3 grades or higher in tCFS vs 236 (59.7%) in the vehicle group (∆ = 12.6%; 95% CI, 6.0%-19.3%; P < .001). These responders showed greater improvement in symptoms at day 29 including dryness (∆ = -4.6; 95% CI, -8.0 to -1.2; P = .007) and blurred vision (Δ = -3.5; 95% CI, -6.6 to -4.0; P = .03) compared with nonresponders. The ESSENCE-2 trial confirmed that treatment with a water-free cyclosporine solution, 0.1%, results in early therapeutic effects on the ocular surface compared with vehicle. The responder analyses suggest that the effect is clinically meaningful in 71.6% of participants in the cyclosporine group. ClinicalTrials.gov Identifier: NCT04523129.

Pattern of increase in Spherical Aberration and Coma After Femtosecond Laser Assisted In-Situ Keratomileusis Using an Aspheric Ablation Profile

Purpose: To determine the contribution of spherical aberration and coma to the total ocular high order aberration before and after femto laser-assisted in-situ keratomileusis using an aspheric ablation profile. Methods: This is a prospective interventional study that was conducted on 34 eyes of 17 patients in the interval between January 2021 and June 2021. Patients did a preoperative aberrometry and corneal tomography. They underwent FS-LASIK surgery using an aspheric ablation profile. The total ocular aberrometry and corneal tomography were repeated one month postoperatively. Results: The mean preoperative contribution of coma to total ocular HOA was 52.16 % with SD of ± 25.59% which declined to 49.48 % with SD of ± 22.53 % postoperatively. The mean preoperative contribution of SA to total ocular HOA was 38.91 % with SD of ± 15.35 % which increased significantly to 51.25 % with SD of ± 16.55 % postoperatively. Conclusion: Post-operative contribution of corneal spherical aberrations to total ocular HOA showed a statistically significant increase compared to pre-operative. However, there was no significant change in coma contribution.

Theoretical Relationship Between the Anterior-Posterior Corneal Curvature Ratio, Keratometric Index, and Estimated Total Corneal Power.

To predict the relationships between the keratometric index value that would match the total Gaussian corneal power and its related variables: anterior and posterior radii of curvature of the cornea, anterior-posterior corneal radius ratio (APR), and central corneal thickness. The relationship between the APR and the keratometric index was approximated by calculating the analytical expression for the theoretical value of the keratometric index, which would make the keratometric power of the cornea equal to the total paraxial Gaussian power of the cornea. The study of the impact of variations in the radius of anterior and posterior curvature and central corneal thickness showed that the difference between exact and approximated best-matching theoretical keratometric index was less than 0.001 for all of the performed simulations. This translated to a variation in the total corneal power estimation of less than ±0.128 diopters. After refractive surgery, the estimated optimal keratometric index value is a function of the preoperative anterior keratometry, the preoperative APR, and the delivered correction. The larger the magnitude of myopic corrections, the greater the increase in postoperative APR value. It is possible to estimate the most compatible value of the keratometric index that allows simulated keratometric power to equal the total Gaussian corneal power. The obtained equations enable the evaluation of the impact of corneal variables such as the APR on the ideal keratometric index value. The use of 1.3375 for the keratometric index results in an overestimation of the total corneal power in most clinical situations. [J Refract Surg. 2023;39(4):266-272.].

Comparison of Refractive Outcomes and Optical Zone Decentration After SMILE Between Patients With Symmetrical and Asymmetrical High Astigmatism.

To compare the refractive outcomes and optical zone decentration between patients with symmetrical and asymmetrical high astigmatism after small incision lenticule extraction (SMILE). This was a prospective analysis of 89 patients (152 eyes) with myopia and astigmatism of more than 2.00 diopters (D) treated with the SMILE procedure. There were 69 eyes with asymmetrical topographies (asymmetrical astigmatism group) and 83 eyes with symmetrical topographies (symmetrical astigmatism group). Decentralization values were assessed using the tangential curvature difference map preoperatively and 6 months after surgery. Decentration, visual refractive outcomes, and induced changes in corneal wavefront aberrations were compared between the two groups 6 months postoperatively. Both groups achieved favorable visual and refractive outcomes, with a mean postoperative cylinder of -0.22 ± 0.23 and -0.20 ± 0.21 D in the asymmetrical and symmetrical astigmatism groups, respectively. In addition, visual and refractive outcomes and induced changes in corneal aberrations were comparable between the asymmetrical and symmetrical astigmatism groups (all P > .05). However, the total and vertical decentration in the asymmetrical astigmatism group was greater than that in the symmetrical astigmatism group (all P < .05), whereas no significant differences were found in the values of horizontal decentration between the two groups (P > .05). There was a weak positive correlation between induced total corneal higher order aberrations and total decentration (r = 0.267, P = .026) in the asymmetrical astigmatism group but not in the symmetrical astigmatism group (r = 0.210, P = .056). An asymmetrical corneal surface might affect treatment centration after SMILE. Subclinical decentration may be associated with the induction of total higher order aberrations, but it did not affect high astigmatic correction or induced corneal aberrations. [J Refract Surg. 2023;39(4):273-280.].