Mean Keratometry Research Articles

Pterygium recurrence and corneal stabilization point after pterygium excision using the controlled partial avulsion fibrin glue technique

Background: This study aimed to evaluate the pterygium recurrence rate and corneal stabilization point after pterygium excision via the controlled partial avulsion fibrin glue technique using multiple corneal parameters. Methods: One hundred eyes of 100 patients who had undergone primary pterygium excision surgery via the controlled partial avulsion fibrin glue technique were retrospectively reviewed. Corneal stabilization points were determined over four follow-up sessions (i.e., the 1st, 3rd, 6th, and 12th months after surgery) based on changes in Simulated-K, corneal irregularity measurement, shape factor, and toric mean keratometry. Post-operative courses were followed for 12 months after surgery. Recurrence was defined as the regrowth of fibrovascular tissue 1 mm past the corneoscleral limbus. Results: No sign of pterygium recurrence and the corneal stabilization point were observed at the third month post-operation. Significance improvements in all corneal parameters were noted between the 1st and 3rd months (both p < 0.001); however, insignificant changes were noted at the following 6th- and 12th-month visits (both p > 0.05). Conclusion: The controlled partial avulsion fibrin glue technique may improve surgical outcomes with long-term recurrence rates equal to or lower than those previously reported. Corneal surface recovery is completed after the third month of the excision procedure.

Factors predicting long-term changes in refraction after lamellar keratoscleroplasty in children with limbal dermoids.

The objective of this study is to determine the factors that predict long-term changes in refraction after lamellar keratoscleroplasty in paediatric patients with limbal dermoids. A retrospective study of 66 children with limbal dermoids who had lamellar keratoscleroplasty correction with more than 1-year follow-up. Univariate and multivariate regression analyses were performed to investigate factors associated with the long term in refractive parameters, including spherical equivalent, astigmatism, and mean keratometry. The change value was defined as the postoperative refractive value minus the preoperative refractive value. The lower the value of changes, the more satisfied the effects on the correction of the preoperative refraction. A total of 66 patients (mean surgical age: 3.5 ± 2.1 years) were assessed with at least 1-year follow-up. Amblyopia treatment duration was the only independent factor predicting the long-term changes in spherical equivalent between baseline and last follow-up visit (β = -0.030, P < 0.001). Lesion encroachment on the central and paracentral cornea (β = 0.502, P = 0.024), suture-related complications (β = 1.571, P < 0.001) and graft rejection (β = 0.983, P = 0.035) were significantly correlated with long-term changes in astigmatism. The long-term changes in refraction were not correlated with surgical age, lesion size, lesion depth, steroid-induced high intraocular pressure and changes in mean keratometry. Suture-related complications and graft rejection should be carefully observed and appropriately treated in order to avoid the possible postoperative increase in astigmatism, especially for patients with lesion encroachment on the central and paracentral cornea. The long-duration amblyopia treatment after surgery appears to have a better correction effect on spherical equivalent in the long term, compared with astigmatism.

Accelerated Pulsed High-Fluence Corneal Cross-Linking for Progressive Keratoconus

To report on 2-year results of accelerated corneal collagen cross-linking (CXL) in progressive ectasia using the Avedro KXL system. Prospective interventional case series. A total of 870 patients (1,192 eyes) attending Moorfields Eye Hospital after CXL were included. All patients undergoing CXL had progressive keratoconus. Corneas with a minimum stromal thickness <375μm were excluded. Riboflavin 0.1% soak duration was 10minutes. High-fluence pulsed UVA was delivered at 30 mW/cm2 for 4minutes, with a 1.5-second on/off cycle (total energy 7.2 J/cm2). Subjective refractive, corneal tomography, and specular microscopy were performed at baseline, 6, 12, and 24months postoperatively. The primary outcome measure was a change in maximum keratometry (Kmax) at 24months. Twelve- and 24-month follow-up data were available on 543 and 213 patients, respectively (mean age 25.4 ± 6.6 years). In mild cones (Kmax < 55 diopter [D]), mean keratometry remained unchanged at 24months. In more advanced disease, we observed modest corneal flattening compared to baseline (Kmax 63.2 ± 6.5 D vs 61.9 ± 8.1 D, P= .02), but no significant changes in central keratometry (K1 or K2). Keratometric stabilization was confirmed in 98.3% of eyes. Mean CDVA, manifest refraction and endothelial cell density did not change. Overall, 2.7% of eyes lost more than 2 lines of CDVA. Accelerated pulsed CXL is a safe, effective, and refractively neutral intervention (at 2 years) to halt disease progression in keratoconus.

Comparative 2-year outcomes of conventional and accelerated corneal collagen crosslinking in progressive keratoconus.

To compare the safety and efficacy of conventional versus accelerated (9 mW/cm2) corneal collagen crosslinking (CXL) in progressive keratoconus at the 2-year follow-up. In this prospective study, consecutive progressive keratoconus patients were randomized to receive either conventional CXL (CCXL) or accelerated CXL (ACXL; using hydroxypropyl methylcellulose-assisted riboflavin imbibition for 10min at 9 mW/cm2). Visual, refractive, keratometric, topographic, and aberrometric outcomes and stromal demarcation line depth (DLD) measurements were compared at the end of a 2-year follow-up. Thirty-two eyes from 32 patients in the CCXL and 27 eyes from 27 patients in the ACXL groups completed 2-year follow-up. At 2y post-CXL, both uncorrected and corrected visual acuities improved significantly in both groups. The improvements in keratometric readings, flattening rate (flattening of the maximum keratometry more than 1 D), 3 topographic indices, and vertical coma were significantly better in the CCXL group compared to the ACXL group (P<0.05). The DLD as measured by anterior segment optical coherence tomography or in vivo confocal microscopy was better detectable and significantly deeper in the CCXL group compared to the ACXL group. The deeper DLD was found to be significantly correlated with improvements in the mean keratometry measurements. Progression was noted in 11.1% of eyes in the ACXL group, whereas progression was not observed in any patient eye in the CCXL group. In this prospective randomized study, ACXL is less effective in halting the progression of keratoconus at a 2-year follow-up compared to CCXL.

Corneal densitometry and topography in patients with primary congenital glaucoma

To compare corneal densitometry and topography variables in patients with primary congenital glaucoma (PCG) and healthy subjects. Cross sectional study, consecutive recruitment with gender- and age-matched control group. Forty eyes of 40 patients in each group were studied with Pentacam corneal topography. The variables compared between the two groups were: intraocular pressure (IOP), visual acuity (VA) and Pentacam (Oculus, Wetzlar, Germany) corneal topography measurements: mean and maximum keratometry (Km, Kmax), cylinder (Cyl), anterior elevation apex (AEA), central anterior elevation (CAE), maximum anterior elevation (MAE), posterior elevation apex (PEA), central posterior elevation (CPE), maximum posterior elevation (MPE), pachymetry and anterior, mid-stromal and posterior corneal densitometry in the 0-2mm, 2-6mm, 6-10mm zones. Significant differences between patients and healthy controls were detected in the topographic variables MAE (P=0.002) and MPE (P<0.001), and in all the densitometry variables (anterior, mid-stromal, posterior for the 0-2mm, 2-6mm and 6-10mm zones) (P<0.001 each). In the PCG group, negative correlation was observed between VA and total densitometry (r=-0.49; P=0.004). Patients with PCG and healthy subjects display differences in corneal densitometry and topographic measurements. PCG patients show greater corneal density with an inverse relationship between visual acuity and higher elevation (anterior and posterior values).

Corneal biomechanical outcome of collagen cross-linking in keratoconic patients evaluated by Corvis ST.

A 6-month evaluation of the topographic and biomechanical changes induced by corneal collagen cross-linking (CXL) in keratoconic eyes using Pentacam and Corvis ST. Longitudinal prospective case series. In this study, 67 eyes of 67 patients with progressive keratoconus (KCN) treated with "Epithelium-off" CXL were evaluated. Patients with stages 1 or 2 of KCN and a corneal thickness of at least 400 μm at the thinnest point were included. Standard ophthalmologic examinations were carried out for all patients. The topographic and biomechanical measurements of the cornea were obtained by Pentacam (Oculus Optikgeräte GmbH, Wetzlar, Germany) and Corvis ST (Oculus Optikgeräte GmbH, Wetzlar, Germany) preoperatively and 6-month postoperatively. The mean age of the participants was 21.68 ± 4.23 years. There was significant difference in mean spherical equivalent (SE) before and 6 months after CXL. Uncorrected and best corrected visual acuity improved postoperatively, although not statistically significant. The mean and maximum keratometry showed a significant decrease 6 months after CXL (0.93 ± 0.38 D and 1.43 ± 0.62 D, respectively p < 0.001). Among Corvis ST parameters, first applanation length and velocity (AL1 and AV1) showed statistically significant changes. The radius at highest concavity changed significantly (0.13 ± 0.37 mm mean increase after CXL; p < 0.001). A significant increase was observed in stiffness parameter A1 (SP-A1; p < 0.001) and significant decreases were noted in integrated radius (IR) and deformation amplitude ratio (DAR; p < 0.001). Analyzing biomechanical changes after corneal cross-linking can provide basis for efficient KCN treatment. Corvis ST parameters demonstrated changes in corneal biomechanical characteristics indicative of stiffing after CXL.

Standardized pachymetry-assisted manual lamellar dissection for Descemet stripping endothelial keratoplasty.

To present an alternative technique (Pachy-DSEK) for the manual preparation of thin endothelial lamellae in Descemet stripping endothelial keratoplasty (DSEK), as well as to evaluate its visual and anatomic outcomes. A retrospective chart review was conducted in 15 cases who underwent DSEK at a private eye clinic in Brazil (INOB, Brasília) from June 2017 to December 2019. All patients had ocular comorbidities and relative contraindications to Descemet membrane endothelial keratoplasty (DMEK). All endothelial lamellae were manually prepared by using a standardized technique. Best corrected visual acuity (BCVA), tomographic parameters and graft's thickness were evaluated preoperatively and at 6 months. Endothelial cell counts were evaluated preoperatively and at 12 to 24 months. During preparation there was one case (6%) of peripheral tear and no tissue was lost. At 6 months, the median BCVA improved from 1.60 to 0.40 logMAR (p = 0.0009). There was no significant change in anterior (p = 0.507) and posterior astigmatism (p = 0.483), anterior (p = 0.683) and posterior mean keratometry (p = 0.767), and total corneal power (p = 0.952). The median central graft thickness at 6 months was 80 µm. Ultrathin grafts (<130 µm) were achieved in 80% of cases. At 12 to 24 months endothelial cell count decreased significantly. Graft's detachment occurred in two cases (13%) and endothelial rejection in one case (6%). By using ultrasonic pachymetry intra-operatively and standardizing graft preparation, most manually dissected endothelial lamellae were ultrathin. Pachy-DSEK was safe and effective for treating endothelial disfunction in eyes with ocular comorbidities. It may be a cost-effective alternative to automated dissection methods.

Agreement Between Two Optical Biometers Based on Large Coherence Length SS-OCT and Scheimpflug Imaging/Partial Coherence Interferometry.

To evaluate the agreement between measurements obtained with a new optical biometer (Argos; Movu Inc) using large coherence length swept-source optical coherence tomography (SS-OCT) and those obtained with an optical biometer with a rotating Scheimpflug camera, combined with partial coherence interferometry (PCI) (Pentacam AXL; Oculus Optikgeräte GmbH) in adults. The following measurements were examined and evaluated: axial length, central corneal thickness (CCT), anterior chamber depth (ACD), mean keratometry, J0 and J45 vectors, and corneal diameter. Measurements with the two biometers were conducted in triplicate per instrument in a random order by the same examiner. Paired t tests were employed to compare the difference between the two devices. The Bland-Altman method was implemented to assess their agreement. A total of 145 patients were enrolled in the study. The differences between the Scheimpflug/PCI-based biometer and the SS-OCT biometer were as follows: -0.02 ± 0.05 mm for axial length, 1.15 ± 5.79 µm for CCT, -0.04 ± 0.04 mm for ACD, -0.28 ± 0.16 diopters (D) for mean keratometry, 0.01 ± 0.11 D for J0, -0.02 ± 0.10 D for J45, and -1.03 ± 0.62 mm for corneal diameter. Bland-Altman plots showed narrow ranges in axial length, CCT, ACD, mean keratometry, and J0 and J45, which implied excellent agreement between the two biometers. Corneal diameter displayed poor agreement, with a 95% limits of agreement ranging from -2.25 to 0.19 mm. Excellent agreement was established between the measurements provided by the new optical biometer based on SS-OCT and the optical biometer using Scheimpflug imaging and PCI, except for corneal diameter. [J Refract Surg. 2020;36(7):459-465.].

Agreement between IOLMaster® 500 and Pentacam® HR for keratometry assessment in type 2 diabetic and non-diabetic patients.

To evaluate inter-device agreement of anterior keratometry obtained by the IOLMaster® 500 and Pentacam® HR in type 2 diabetic and non-diabetic patients. Corneal measurements were sequentially performed in 60 diabetes mellitus (DM) and 48 age and sex-matched controls undergoing cataract surgery. Variables recorded included flat and steep keratometry, mean keratometry (Km), astigmatism magnitude, axis location, J0 and J45 components. Bland-Altman plots and intraclass correlation coefficients were used for examination of agreement. Subgroup analyses were performed for astigmatism magnitude, diabetes duration, hemoglobin A1c (HbA1c) levels and diabetic retinopathy (DR) stage. Agreement for Km and astigmatism magnitude were considered good and moderate, with 95% limits of agreement (LoA) of -1.09 to 1.23 diopters (D) and -0.83 to 0.86 D in DM group, respectively; and -0.59 to 0.72 D and -0.98 to 0.75 D in non-DM group, respectively. In contrast, the 95% LoA for corneal axis exceeded the clinically relevant margins in both groups. In the total sample, only 41 eyes (38%) had a smaller than 5-degree difference. Diabetes duration, HbA1c levels and DR stage were not found to significantly affect agreement. Logistic regression showed that higher corneal power (P=0.021) and astigmatism magnitude (P=0.011) were associated with a decreased risk of having a difference in axis location greater than 10-degrees. In both groups, IOLMaster and Pentacam agree well for corneal power and moderately for astigmatism. However, axis location disagreement is frequent in eyes with flatter corneas and small amounts of astigmatism.

Influence of Preoperative Keratometry on Refractive Outcomes for Myopia Correction With Small Incision Lenticule Extraction.

To evaluate the effect of preoperative keratometry on refractive outcomes after small incision lenticule extraction (SMILE) for myopia. This retrospective study comprised 515 consecutive eyes that had SMILE to correct myopia. Pearson correlation and linear regression were used to determine the relationship between residual spherical equivalent and preoperative keratometry. The same analyses were repeated in the quartiles with the lowest and highest preoperative myopia. Preoperatively, the mean spherical equivalent was -5.67 ± 1.87 diopters (D) (range: -1.63 to -9.75 D) and the mean keratometry was 43.10 ± 1.30 D (range: 38.90 to 47.00 D). Three months postoperatively, the mean spherical equivalent was -0.07 ± 0.18 D. After adjustment for age, sex, and preoperative spherical equivalent, greater postoperative undercorrection occurred in eyes with steeper corneas (P = .001). Each diopter of steeper keratometry resulted in 0.52% (0.03 D) more undercorrection. Correlation between the mean preoperative keratometry and residual spherical equivalent was significant in the lower preoperative myopia group (r = -0.24, P = .006), but not significant in the higher myopia group (r = -0.02, P = .809). Preoperative keratometry affects refractive outcomes after SMILE. Steeper corneas have greater undercorrection, especially in eyes with low myopia. Knowledge of the correlation between refractive outcomes of SMILE and keratometry would help in modifying current treatment algorithms. [J Refract Surg. 2020;36(6):374-379.].

Efficacy of Standard and Accelerated (10 Minutes) Corneal Crosslinking in Keratoconus Stabilization.

PurposeTo evaluate whether Accelerated CXL for 10 minutes is as effective as standard CXL for 30 minutes for the treatment of progressive keratoconus.Patients and MethodsEighty-two eyes of 62 patients with keratometry examinations performed before and 6 months after surgery were studied. A total of 39 eyes underwent standard CXL with UVA irradiation of 3 mW/cm2 for 30 minutes and 32 eyes underwent Accelerated CXL UVA irradiation of 9 mW/cm2 for 10 minutes. The eyes of all patients had corneal thicknesses of at least 450 microns (400 microns after epithelium removal).ResultsThe means of the keratometry measurements in the preoperative period for the eyes subjected to standard CXL were 46.27 dioptres (D) on the flat axis (K1) and 48.93 D on the steep axis (K2). Postoperatively, K1 was 46.21 D and K2 was 48.97 D, a difference without statistical significance (p = 0.47 and p = 0.48, respectively). In the Accelerated CXL protocol, the preoperative measurements were 44.55 D and 46.19 D for K1 and K2, respectively. In the postoperative period, K1 was 43.37 D, and K2 was 46.64 D (p = 0.38 and p = 0.27, respectively). In the standard group, the mean maximum keratometry (Kmax) preoperatively was 55.87 D, with no statistical significance (p = 0.29). In the preoperative period, the Kmax of the Accelerated group was 51.15 D, with no statistical significance (p = 0.32).ConclusionBased on the keratometry results, the accelerated protocol was as effective as the standard protocol for keratoconus stabilization.

Accuracy of a new intraocular lens power calculation method based on artificial intelligence.

The purpose of this study is to develop and assess the accuracy of a new intraocular lens (IOL) power calculation method based on machine learning techniques. The following data were retrieved for 260 eyes of 260 patients undergoing cataract surgery: preoperative simulated keratometry, mean keratometry of posterior surface, axial length, anterior chamber depth, lens thickness, and white-to-white diameter; model and power of implanted IOL; and subjective refraction at 3 months post surgery. These data were used to train different machine learning models (k-Nearest Neighbor, Artificial Neural Networks, Support Vector Machine, Random Forest, etc). Implanted lens characteristics and biometric data were used as input to predict IOL power and refractive outcomes. For external validation, a dataset of 52 eyes was used. The accuracy of the trained models was compared with that of the power formulas Holladay 2, Haigis, Barrett Universal II, and Hill-RBF v2.0. The SD of the prediction error in order of lowest to highest was the new method (designated Karmona) (0.30), Haigis (0.36), Holladay 2 (0.38), Barrett Universal II (0.38), and Hill-RBF v2.0 (0.40). Using the Karmona method, 90.38% and 100% of eyes were within ±0.50 and ±1.00 D respectively. The method proposed emerged as the most accurate to predict IOL power.

Hyperopic laser keratorefractive surgery: Do steep corneas have worse outcomes?

To report the visual and refractive outcomes of hyperopic patients undergoing laser keratorefractive surgery in preoperatively steep corneas versus a matched control group. Retrospective cohort study. All patients underwent photorefractive keratectomy (PRK) or laser-assisted in situ keratomileusis (LASIK) at Care-Vision Laser Centers, Tel-Aviv, Israel, between 1/2000 and 11/2016. Patients were divided into two groups: steep corneas (mean keratometry ≥ 44.00D) and control group (mean keratometry < 44.00D). The two study groups were matched by age, gender, sphere and cylinder. Only the right eye of each patient was included. Outcomes included postoperative uncorrected distance visual acuity (UDVA), best-corrected distance visual acuity (CDVA), safety and efficacy indexes, refractive outcomes and retreatment rates. Five hundred and two patients were included. Both groups were similar in demographic data, visual acuity and refraction. Postoperatively, the steep corneas group had a significantly higher mean keratometry as compared to the control group (46.52 ± 1.43D vs 44.58 ± 1.68D, p < 0.001), Kmin (46.04 ± 1.50D vs 44.12 ± 1.76D, p < 0.001) and Kmax (46.99 ± 1.51D vs 45.03 ± 1.77D, p < 0.001). Both groups had similar postoperative UDVA and CDVA and achieved a similar final sphere (0.64 ± 0.19 vs 0.54 ± 1.19, p = 0.44) and cylinder (- 0.89 ± 0.59 vs - 0.86 ± 0.72, p = 0.67). Both groups had a similar efficacy index (0.92 ± 0.22 vs 0.90 ± 0.25, p = 0.33) and similar retreatment rates (4.2% vs 3.5%, p = 0.74). None of the patients in either group underwent more than one retreatment throughout the follow-up period. Hyperopic patients with steep corneas undergoing laser keratorefractive surgery can achieve adequate visual and refractive outcomes, similar to control group.

A Comparative Study of Total Corneal Power Using a Ray Tracing Method Obtained from 3 Different Scheimpflug Camera Devices

We sought to assess the agreement of ray-traced corneal power values by 3 Scheimpflug tomographers tp construct the corresponding arithmetic adjustment factor in comparison with an automated keratometer (IOLMaster) and a conventional Placido-based topographer (Allegro Topolyzer). Prospective reliability analysis. A total of 74 eyes from 74 healthy subjects who underwent corneal power measurements using Pentacam, Sirius, Galilei, IOLMaster, and Allegro Topolyzer were included. Ray-traced corneal power values, such as total corneal refractive power (TCRP), mean pupil power (MPP), total corneal power (TCP), mean keratometry (Km), and simulated keratometry (SimK) were recorded respectively and analyzed using one-way analysis of variance (ANOVA) and Bland-Altman plots. Among the 3 ray-traced corneal power values, TCRP and MPP did not differ significantly (P= 0.81), whereas TCP presented a slightly significant larger value (P < 0.001). Compared to Km or SimK, corneal power measurements by the ray tracing method exhibited significantly lower values (P < 0.001). Bland-Altman plots disclosed that the 3 Scheimpflug tomographers showed similar 95% limits of agreement after arithmetic adjustment compared with Km (-0.40 to 0.40 D,-0.39 to 0.39 D, and-0.35 to 0.34 D) or SimK (-0.50 to 0.51 D,-0.43 to 0.42 D, and-0.46 to 0.46 D). Ray-traced corneal power values obtained using 3 Scheimpflug tomographers with default diameter settings were similar, indicating that they could be used interchangeably in daily clinical practice. The 3 Scheimpflug tomographers were satisfactory in agreement after arithmetical adjustment compared with conventional automated keratometer or Placido-based topographer.

Orthokeratology in Moderate Myopia: A Study of Predictability and Safety.

PurposeLiterature is relatively silent on safety profile and predictability of orthokeratology lenses in terms of myopia correction and prevention of further progression, especially in semi-tropical countries; this study was designed to fill this gap.MethodsThis prospective, intervention case series enrolled 30 eyes of 30 patients with myopia up to –5.5 diopters (D). Patients were randomized into two groups of 15 each; the study group was prescribed overnight orthokeratology (OK) lenses, while the control group used daily wear conventional soft contact lenses. Follow-up examinations were performed after 1 h and 6 h, and then at 1, 7, 15, 30 days, and 4 months post lens wear. Uncorrected visual acuity (UCVA), contrast sensitivity, keratometry, central corneal thickness (CCT), and tear film break up time (TBUT) were evaluated at each follow-up examination.ResultsAll patients attained a visual acuity of 0.00 Logarithm of the Minimum Angle of Resolution (logMAR) after one week of lens use, which was maintained throughout the study period. While patients allotted to the study group had a gain of 8.1 Snellen lines (UCVA), those in the control group gained 8.9 lines (BCVA) at the end of follow-up period. In the OK group, cornea showed a flattening of 0.8 D (mean keratometry) after single overnight usage of OK lens and overall flattening of 1.2 D compared to baseline, at the end of four months. The change in contrast sensitivity, corneal endothelial specular count, axial length and tear film status was not significant in either group.Conclusion Orthokeratology is an effective and safe modality to correct moderate myopia in motivated young adults. No side effects were encountered after a short-term follow-up in participants who resided in semi-tropical environments.

Posterior Corneal Surface Changes After Pterygium Excision Surgery

To evaluate the effect of pterygium excision on the posterior corneal surface and analyze the factors associated with those changes. A prospective, interventional study including 33 eyes of 31 patients who underwent pterygium excision at the Tel Aviv Medical Center (Tel Aviv, Israel). Exclusion criteria included corneal dystrophy, pseudopterygium, corneal scarring, or previous ocular surgery in the treated eye. Data were obtained by using the Galilei dual Scheimpflug analyzer. Recorded posterior corneal data included steep keratometry, flat keratometry, mean keratometry, corneal astigmatism, best-fit sphere, and the squared eccentricity index (e). Posterior surgically induced astigmatism (SIA) was calculated to demonstrate the astigmatic effect of surgery. Anterior-segment high resolution optical coherence tomography was used to measure pterygium dimensions (depth and horizontal/vertical size). The mean age was 53.7 ± 16.7 years. Posterior corneal SIA was 0.9 ± 1.1 D (P < 0.001) and was significantly correlated with age (r = 0.568, P = 0.002), horizontal pterygium size (r = 0.387, P = 0.046), and preoperative posterior astigmatism (r = 0.688, P < 0.001). In a multivariable analysis, only age (coefficient = 0.010, P = 0.038) and preoperative posterior astigmatism (coefficient = 0.648, P = 0.002) remained significant. Pterygium dimensions were not significantly associated with SIA magnitude. Flat keratometry steepened by 0.5 ± 1.1 D (P = 0.019), mean keratometry steepened by 0.3 ±0.6 D (P = 0.035), posterior astigmatism was reduced by 0.4 ± 1.2 D (P = 0.072), and e decreased by 5.1 ± 17.3 (P = 0.021). Pterygium excision has a significant astigmatic effect on the posterior corneal surface. The astigmatic effect increases with age and with higher preoperative posterior astigmatism. Pterygium depth and size are not associated with the degree of surgical astigmatic effect.

Accelerated corneal crosslinking in children with keratoconus: 5-year results and comparison of 2 protocols

To evaluate long-term clinical results of 2 different accelerated corneal crosslinking (CXL) protocols in pediatric patients with keratoconus. Beyoğlu Eye Training and Research Hospital, Istanbul, Turkey. Retrospective case-control study. Patients who were younger than 18 years were included in the study. Group 1 received 4 minutes of illumination at 30 mW/cm, and Group 2 received 5 minutes of illumination at 18 mW/cm. Uncorrected and corrected distance visual acuities, manifest refraction, corneal topographic parameters, and corneal higher-order aberrations (HOAs) were evaluated at baseline and during 1-, 3-, and 5-year follow-up visits. A total of 143 eyes from 86 patients were included in the study. There were 30 eyes in Group 1 and 113 eyes in Group 2. The mean follow-up time was 4.15 ± 0.99 years. Mean keratometry (K) and/or maximum K progressed ≥1.00 diopter (D) in 7 eyes (23.3%) in Group 1 and 19 eyes (16.8%) in Group 2 (P = .411). Mean K and/or maximum K decreased ≥2.00 D in 2 eyes (6.7%) in Group 1 and 24 eyes (21.2%) in Group 2 (P = .06). In Group 1, there were no statistically significant differences in topographic parameters during follow-up. In Group 2, there was a statistically significant reduction in total HOA and coma during the 5-year visit when compared with the preoperative visit (P = .005 and P = .045, respectively). Accelerated CXL is beneficial in terms of halting the progression of keratoconus in pediatric patients throughout 5 years of follow-up examinations. An increased irradiance with a reduced application time reduces the topographic effects of CXL.

Evaluating Refractive and Visual Outcomes After Bilateral Implantation of an Apodized Diffractive Multifocal Toric Intraocular Lens with a Moderate Add in the Dominant Eye and a Higher Add in the Fellow Eye.

PurposeTo review refractive, visual acuity, defocus curve and subjective visual quality results after bilateral implantation of an apodized diffractive toric intraocular lens (IOL) with a moderate add in the dominant eye and a higher add in the non-dominant eye.SettingOne site in Gainesville, GA, USA.DesignSingle arm, non-randomized prospective study.MethodsThis was a single-arm prospective study of visual acuity and subjective visual quality after implantation of a toric low-add apodized diffractive multifocal IOL in the dominant eye and a higher add IOL of the same type in the non-dominant eye three months after surgery. Binocular visual acuity at 4 m, 60 cm and 40 cm was tested. Other tests included refraction, defocus curve measurement and evaluation of the quality of vision. Toric IOL orientation was also measured.ResultsA total of 29 subjects were enrolled. There were no statistically significant differences in the mean keratometry, corneal astigmatism or IOL sphere power implanted in the dominant and non-dominant eyes. Vision was preferred without any correction in more than half of the eyes tested (32/58, 55%). The residual refractive astigmatism was ≤ 0.50 D in 100% of eyes. Seventy-five percent of subjects (22/29) had 0.10 logMAR (20/25 Snellen) binocular uncorrected visual acuity at all tested distances. Glare and haloes were the most common visual disturbances, but most subjects (22/29, 76%) reported that they were not bothered by any visual disturbances. In 97% of eyes (56/58), the measured difference in orientation between 1 month and 3 months was less than 5 degrees, with no change more than 14 degrees.ConclusionThis blended bifocal IOL modality appears to be well-tolerated by subjects with a good range of vision and minimal bother from visual disturbances.

One-year visual and astigmatic outcomes of keratoconus patients following sequential crosslinking and topography-guided surface ablation: the TOPOLINK study.

To evaluate long-term visual and astigmatic outcomes of sequential corneal crosslinking (CXL) followed by topography-guided photorefractive keratectomy (PRK). Single-practice outpatient setting. Retrospective case review. This is a single-surgeon retrospective case review of eyes with keratoconus undergoing sequential CXL and then topography-guided PRK. Change in uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), topographic, refractive, and keratometric astigmatism was analyzed using power vector analyses at baseline, 6 months, and 12 months after topography-guided PRK. Changes in higher-order aberrations (HOAs), posterior astigmatism, spherical equivalent (SE), and central corneal thickness (CCT) were also analyzed. Correlations between age, time between CXL and PRK, sex, manifest SE, CCT, maximum and average keratometric values, and HOAs were evaluated for significance. Of the 62 eyes studied, regardless of refractive treatment, topography-guided PRK following CXL in patients with keratoconus improved CDVA (mean 20/30; 2-line improvement) and UDVA (mean 20/50; 4-line improvement). Over 12 months, visual acuity continued to improve across all eyes treated (P < .001). Overall, there were significant improvements in corneal astigmatism, maximum keratometry, mean keratometry, SE, posterior astigmatism, and total HOAs. No significant correlations were found between age, sex, time elapsed between CXL and PRK, and age at the time of either procedure on final visual acuity. Results of this study reinforced previous findings that topography-guided PRK in previously cross-linked keratoconus eyes proves to be an efficacious and safe method for improving visual acuity and reducing irregular corneal astigmatism, with continued improvement.

Extended Depth of Focus Versus Monofocal IOLs: Objective and Subjective Visual Outcomes.

To evaluate and compare the objective and subjective outcomes between bilateral implantation of the extended depth of focus (EDOF) Mini Well intraocular lens (IOL) and the aspheric monofocal Mini-4-Ready IOL (both SIFI S.p.A., Catania, Italy). This prospective comparative study included 25 patients (50 eyes) bilaterally implanted with an EDOF Mini Well IOL (EDOF group) and 25 patients (50 eyes) bilaterally implanted with a Mini-4-Ready IOL (monofocal group). Three-month follow-up data included corrected and uncorrected distance visual acuity at 4 m and 80, 67, and 40 cm. Defocus curves, subjective and objective contrast sensitivity, and objective optical quality (modulation transfer function cutoff and Strehl ratio calculated with Optical Quality Analysis System [OQAS]; Visiometrics SL, Terrassa, Spain), halometry, and reading performance were measured. Subjective visual quality was evaluated based on National Eye Institute Refractive Error Quality of Life Instrument 42 (NEI RQL-42) scores. Postoperative uncorrected and corrected monocular and binocular intermediate and near visual acuity was significantly better in the EDOF group (P < .001). No differences were observed for distance visual acuity (P ⩾ .312). Defocus curve outcomes for myopic values were better in the EDOF group (P < .001). No significant differences were found in hyperopic (obtained in steps of +0.50 diopters [D] from emmetropia to 1.50 D) values (P ⩾ .095), contrast sensitivity curves (P ⩾ .087), or OQAS outcomes (P ⩾ .138). Halometric values were significantly better in the monofocal group (P < .05). There was a correlation between mean keratometry values and intermediate/near visual acuity. Significantly better NEI RQL-42 subscale scores for near vision, far vision, activity limitations, glare, dependence on correction, and suboptimal correction were noted in the EDOF group (P < .05). Intermediate and near visual acuity was better after EDOF IOL than after aspheric monofocal IOL implantation while maintaining similar levels of visual quality, except for halo perception. [J Refract Surg. 2020;36(4):214-222.].