The latest medical research on Ophthalmic Pathology

The research magnet gathers the latest research from around the web, based on your specialty area. Below you will find a sample of some of the most recent articles from reputable medical journals about ophthalmic pathology gathered by our medical AI research bot.

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Three-Year Outcomes of Under-flap Stromal Bed CXL for Early Post-LASIK Ectasia.

Refractive Surgery

To investigate the 36-month clinical outcomes of under-flap stromal bed CXL (ufCXL) and report on its ability to stabilize post-laser in situ keratomileusis (LASIK) ectasia.

This case series included 20 eyes with diagnosed early post-LASIK ectasia treated with ufCXL. Inclusion criteria were early, mild post-LASIK ectasia, defined as new-onset postoperative manifest refraction cylinder of 1.50 diopters (D) or less, with new topographic inferior steepening consistent with ectasia, uncorrected distance visual acuity of 20/40 or better, and corrected distance visual acuity of 20/25 or better. The existing LASIK flap was lifted, 0.25% isotonic riboflavin was applied directly to the stromal bed, the flap was repositioned, and 18 mW/cm2 ultraviolet light was applied for 5 minutes to the corneal flap surface. Post-ufCXL ophthalmic data were compared to pre-ufCXL baseline measurements.

Visual outcomes were maintained pre-ufCXL to 36 months post-ufCXL, with preserved safety index (P = .6545), efficacy index (P = .4980), spherical equivalent accuracy (P = .1536), defocus equivalent accuracy (P = .1032), central corneal thickness (P = .5196), and corneal irregularity indices at 3 mm (P = .8548) and 5 mm (P = .3399). Refractive astigmatism significantly decreased from 0.83 to 0.55 D pre-ufCXL to post-ufCXL (P = .0439), as did maximum keratometry from 42.40 to 42.00 D pre-ufCXL to post-ufCXL (P = .0420). The ufCXL demarcation line depth was 336 ± 21 µm post-ufCXL, with normal endothelial cell density (2,574 ± 203 cells/mm2). Only 1 of 20 eyes showed evidence of progression of 1.00 D in maximum keratometry.

The ufCXL procedure shows promise in stabilizing early post-LASIK ectasia. Visual function, refractive astigmatism, maximum keratometry, and corneal irregularity indices were statistically maintained at 36 months postoperatively. [J Refract Surg. 2022;38(8):511-519.].

Detection of Corneal Ectasia Using OCT Maps of Pachymetry and Posterior Surface Mean Curvature.

Refractive Surgery

To quantify the abnormal corneal thinning and posterior surface steepening that is observed in keratoconus with an Ectasia Index.

Optical coherence tomography (OCT) was used to image the corneas of normal individuals and patients with varying stages of keratoconus (manifest, subclinical, and forme fruste). Maps of corneal pachymetry and posterior surface mean curvature were generated, and an Ectasia Index was calculated by multiplying Gaussian fits obtained from the two types of maps. Repeated five-fold cross-validation was used to evaluate the ability of the Ectasia Index to differentiate between normal and keratoconic eyes. The classification performance of the Ectasia Index was compared to minimum pachymetry and maximum posterior mean curvature.

Thirty-two eyes from 16 normal individuals, 89 eyes from 63 patients with manifest keratoconus, 16 eyes from 15 patients with subclinical keratoconus, and 26 eyes from 26 patients with forme fruste keratoconus were included in the study. During cross-validation, 100% of the eyes with manifest (89 of 89) and subclinical (16 of 16) keratoconus were correctly classified by the Ectasia Index. The average classification accuracy for the forme fruste keratoconus group was 63 ± 21% (16.4 of 26). The specificity for the normal group was 91 ± 10% (29.1 of 32). The Ectasia Index had a higher sensitivity for keratoconus detection and similar specificity in comparison to minimum pachymetry and maximum posterior mean curvature.

The Ectasia Index could be a valuable additional metric for clinicians to consider when screening for keratoconus. [J Refract Surg. 2022;38(8):502-510.].

Fresh Human Myopic Lenticule Intrastromal Implantation for Keratoconus Using SMILE Surgery in a Long-term Follow-up Study: Ultrastructural Analysis by Transmission Electron Microscopy.

Refractive Surgery

To investigate new intrastromal histological structures that develop after myopic human lenticular implantation in keratoconus with femtosecond laser-assisted small incision lenticule extraction (SMILE) surgery using transmission electron microscopy.

Sixty eyes with advanced keratoconus indicated for corneal transplantation were included in this study. Fresh myopic lenticular implants were placed in all eyes through SMILE surgery. Lenticular implants were extracted from patients with myopic refractive errors of the cornea, untreated keratoconus, and treated keratoconus following 1, 2, and 3 years of surgery. These five lenticular samples were examined under the electron microscope and compared.

Disorganized and thinned collagen fibers were observed in the stroma with degenerative stromal cells (telocyte-like cells and keratocytes) in the keratoconic cornea. Apoptotic bodies and cell debris were easily observed near the disorganized fibers. In contrast, the myopic refractive error of the control and treatment groups demonstrated well-organized parallel lamellar structures. Healthy keratocytes and telocyte-like cells were observed in samples obtained 1, 2, and 3 years after lenticular implantation. Thus, telocyte-like cells may be activated by appropriate stimuli, such as stem cells, and be involved in stromal regeneration.

Fresh myopic intrastromal lenticular implantation is a safe, economical, and reliable technique that leads to increased corneal thickness, improved visual acuity, and the regeneration of healthy keratocytes and telocyte-like cells that are involved in stromal regeneration. [J Refract Surg. 2022;38(8):520-528.].

The Impact of Epithelial Remodeling on Surgical Techniques Used in Topography-guided Surface Ablation in Irregular Corneas.

Refractive Surgery

To analyze the optical consequences of epithelial remodeling in irregular corneas and their impact on the choice of different surface ablation techniques.

Anterior corneal and stromal surface topographies and epithelial thickness maps were analyzed in 24 eyes with irregular corneal optics. On two of the eyes, four different surface ablation techniques were simulated: (1) conventional anterior topography-guided photorefractive keratectomy (PRK), (2) transepithelial phototherapeutic keratectomy (PTK), (3) transepithelial anterior topography-guided PRK, and (4) stromal topography-guided PRK.

Stromal surface topographies showed higher keratometric values, astigmatism, asphericity, and corneal higher order aberrations compared to topographies of anterior corneas covered by epithelium. Transepithelial anterior topography-guided PRK and stromal topography-guided PRK both resulted in regularized stromal surface, transepithelial PTK achieved partial regularization corresponding to the smoothing effect of the epithelial remodeling, and conventional anterior topography-guided PRK delivered after epithelial removal resulted in residual stromal surface irregularities.

The difference in optical landscapes between the stromal and anterior surfaces in irregular corneas will represent a source of error when anterior topography-guided treatments are delivered on the deepithelialized stroma, as in conventional PRK. In contrast, anterior topography-guided ablations performed as transepithelial PRK and stromal topography-guided PRK delivered after epithelial removal address the full stromal irregularity, whereas transepithelial PTK alone may be used when topography-guided treatments are not possible. The authors conclude topography-guided PRK of irregular corneas should lead to significantly improved regularization only if it includes the effect of epithelial remodeling. [J Refract Surg. 2022;38(8):529-537.].

Through-Focus Response of Extended Depth of Focus Intraocular Lenses.

Refractive Surgery

To investigate extended depth of focus intraocular lenses (EDOF IOLs), intended to extend the depth of field after cataract surgery in a comparative study at the optical bench.

An optical bench with either green or white light was used for this study. The artificial cornea used exhibited a spherical aberration of 0.2 µm. Examinations of the following lenses with a pupil opening of 3 and 4.5 mm were carried out: AcrySof IQ Vivity (Alcon Laboratories, Inc), Isopure (PhysIOL), Tecnis Eyhance (Johnson & Johnson), Vivinex Impress (Hoya Surgical Optics), and xact (Santen).

Using green light and a pupil aperture of 3 mm, the AcrySof IQ Vivity showed the highest light energy for the intermediate area, whereas the Isopure and Vivinex Impress provided the highest energy for distance vision. Under the same examination conditions with a pupil opening of 4.5 mm, all lenses showed a low light distribution for the intermediate range. Regarding light distribution for distance, the Tecnis Eyhance had the highest light intensity. Using white light, the curves became much wider and more similar to each other.

The five EDOF lenses investigated differ mainly by their different weighting of energy between the far and intermediate ranges. [J Refract Surg. 2022;38(8):497-501.].

Enhanced Monofocal Versus Conventional Monofocal Intraocular Lens in Cataract Surgery: A Meta-analysis.

Refractive Surgery

To compare different outcomes of an enhanced monofocal intraocular lens (IOL) versus a conventional monofocal IOL implantation after cataract surgery.

The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guideline was used for abstracting data and assessing quality. Comparative studies between enhanced monofocal versus conventional monofocal IOL implantations reporting outcomes in monocular and binocular visual acuities at various distances, spectacle independence, contrast sensitivity, optical quality, and adverse effects were identified from three databases. Meta-analysis, sensitivity analysis, and subgroup analysis were performed.

A total of 680 eyes implanted with an enhanced monofocal IOL (Tecnis Eyhance ICB00; Johnson & Johnson) and 647 eyes with a conventional monofocal IOL from 3 randomized controlled trials and 9 comparative studies were included. The enhanced monofocal IOL showed better monocular uncorrected intermediate visual acuity (UIVA) (mean difference [MD]: -0.11 logMAR; 95% CI: -0.12 to -0.09), binocular UIVA (MD: -0.17 logMAR; 95% CI: -0.23 to -0.11), and binocular uncorrected near visual acuity performance (MD: -0.17 logMAR; 95% CI: -0.29 to -0.04) than the conventional monofocal IOL. More patients were spectacle free at intermediate distance with the enhanced monofocal IOL (odds ratio: 12.9; 95% CI: 6.2 to 27.0). Both monocular (MD: -0.002 logMAR; 95% CI: -0.01 to 0.01) and binocular (MD: 0.01 logMAR; 95% CI: -0.02 to 0.03) uncorrected distance visual acuity revealed non-significant differences between the IOL designs. Contrast sensitivity, photic phenomenon, and adverse effects were comparable.

Enhanced monofocal IOLs effectively improved unaided intermediate vision with similar distance performance relative to conventional monofocal IOLs. This was achieved without compromising the contrast sensitivity or inducing photic phenomena. [J Refract Surg. 2022;38(8):538-546.].

Large Population Outcomes of Small Incision Lenticule Extraction in Young Myopic Patients.

Refractive Surgery

To evaluate the outcomes of small incision lenticule extraction (SMILE) for myopia in a large population of young adults.

In this retrospective case series, the patient population consisted of the first 4,138 consecutive SMILE treatments using the VisuMax femtosecond laser (Carl Zeiss Meditec) between 2012 and 2018 at the London Vision Clinic. Inclusion criteria were myopic spherical equivalent up to -9.00 diopters (D), cylinder up to 6.00 D, corrected distance visual acuity of 20/20 or better, age younger than 40 years, and follow-up of 12 months. Outcomes analysis was performed using the Standard Graphs for Reporting Refractive Surgery.

Data were available at 12 months in 3,722 eyes (90%), and 416 eyes (10%) were lost to follow-up. Mean attempted spherical equivalent refraction (SEQ) was -4.61 ± 1.84 D (range: -1.12 to -9.00 D). Mean cylinder was -0.78 ± 0.66 D (range: 0.00 to -6.00 D). Postoperatively, the mean SEQ relative to target was -0.13 ± 0.30 D (range: -1.35 to +1.25 D) and was within ±0.50 D in 88.1% and ±1.00 D in 99.6% of eyes. Uncorrected distance visual acuity was 20/20 or better in 95.4% of eyes and 20/25 or better in 98.7% of eyes. One line of CDVA was lost in 3.0% of eyes, and 0.08% (n = 3) lost two or more lines of CDVA, for which CDVA was restored following phototherapeutic keratectomy treatment. There was a statistically significant improvement of 0.05, 0.06, 0.07, and 0.07 log units for contrast sensitivity at 3, 6, 12, and 18 cycles per degree, respectively (P < .001).

SMILE achieved excellent outcomes for myopia up to -9.00 D with cylinder up to -5.50 D for a large population in patients without presbyopia. [J Refract Surg. 2022;38(8):488-496.].

Predictors of Femtosecond Laser-Assisted Arcuate Keratotomy Efficacy for Astigmatism Correction in Cataract Surgery.

Refractive Surgery

To evaluate the predictors related to the efficacy of epithelium- and Bowman membrane-penetrating femtosecond laser-assisted arcuate keratotomy (FSAK) in the treatment of preoperative astigmatism in patients with cataracts and to clarify the predictive role of the incision-to-limbus distance.

This retrospective study included patients who underwent femtosecond laser-assisted cataract surgery combined with FSAK using the LenSX platform (Alcon Laboratories, Inc) at Beijing Aier-Intech Eye Hospital from March 2017 to December 2021. The Lenstar LS900 (Haag-Streit, Inc) was used to measure the horizontal corneal diameter, and ImageJ software (National Institutes of Health) was used to measure the vertical corneal diameter and incision-to-limbus distance. Finally, the measured values were converted. Changes in corneal astigmatism before and 3 months after surgery were analyzed using Alpins vector analysis. Correlation analysis and regression analysis were used to evaluate the factors associated with surgically induced astigmatism (SIA) in preoperative ocular biometric parameters.

The study included 94 eyes of 94 patients. The mean target induced astigmatism was 1.36 ± 0.44 diopters (D), SIA was 0.82 ± 0.43 D, and mean difference vector was 0.70 ± 0.40 D. Pearson correlation analysis and univariate regression analysis showed that preoperative corneal astigmatism, arcuate keratotomy arc length, incision-to-limbus distance, and astigmatism type were significant predictors of SIA. Multiple variable regression analysis included parameters such as age, arcuate keratotomy arc length, and incision-to-limbus distance and established a multiple regression model of SIA (all P < .01).

The incision-to-limbus distance was a significant independent predictor of SIA, and inclusion of this parameter may further improve the accuracy of the nomogram. [J Refract Surg. 2022;38(8):480-486.].

Heidelberg Anterion Swept-Source OCT Corneal Epithelial Thickness Mapping: Repeatability and Agreement With Optovue Avanti.

Refractive Surgery

To assess the repeatability of corneal epithelial thickness mapping in virgin, post-laser refractive surgery (PLRS), and keratoconic eyes using a novel swept-source optical coherence tomographer (SS-OCT), and to determine the agreement of the measurements with a validated spectral-domain (SD) OCT.

Analysis of 90 virgin, 46 PLRS, and 122 keratoconic eyes was performed. Three consecutive measurements of each eye were acquired with the Anterion SS-OCT and Avanti SD-OCT devices, and averages of the epithelial thickness mapping were calculated in the central 2-mm zone and in the 2- to 5-mm and 5- to 7-mm diameter rings. The repeatability was analyzed using pooled within-subject standard deviation (Sw). The agreement was assessed by Bland-Altman analysis and paired t tests.

The repeatability ranges of the Anterion and Avanti epithelial thickness mapping measurements were Sw: 0.60 to 1.36 µm and Sw: 0.75 to 1.96 µm, respectively. The 95% limits of agreement of the Anterion and Avanti were 0.826 to 8.297. All values of the thickness measurements with the Anterion were lower than those of the Avanti, with the mean differences being 4.06 ± 1.81, 3.26 ± 2.52, and 3.68 ± 2.51 µm in virgin, PLRS, and keratoconic eyes, respectively (P < .001 for all).

The repeatability of the Anterion's epithelial thickness mapping was higher than that of the Avanti. In terms of the agreement between the Anterion and Avanti, the epithelium measured by the Anterion was always thinner than that of the Avanti, making their interchangeable use unsuitable without corrections. [J Refract Surg. 2022;38(6):356-363.].

Combining Spectral-Domain OCT and Air-Puff Tonometry Analysis to Diagnose Keratoconus.

Refractive Surgery

To investigate the diagnostic capacity of spectral-domain optical coherence tomography (SD-OCT) combined with air-puff tonometry using artificial intelligence (AI) in differentiating between normal and keratoconic eyes.

Patients who had either undergone uneventful laser vision correction with at least 3 years of stable follow-up or those who had forme fruste keratoconus (FFKC), early keratoconus (EKC), or advanced keratoconus (AKC) were included. SD-OCT and biomechanical information from air-puff tonometry was divided into training and validation sets. AI models based on random forest or neural networks were trained to distinguish eyes with FFKC from normal eyes. Model accuracy was independently tested in eyes with FFKC and normal eyes. Receiver operating characteristic (ROC) curves were generated to determine area under the curve (AUC), sensitivity, and specificity values.

A total of 223 normal eyes from 223 patients, 69 FFKC eyes from 69 patients, 72 EKC eyes from 72 patients, and 258 AKC eyes from 258 patients were included. The top AUC ROC values (normal eyes compared with AKC and EKC) were Pentacam Random Forest Index (AUC = 0.985 and 0.958), Tomographic and Biomechanical Index (AUC = 0.983 and 0.925), and Belin-Ambrósio Enhanced Ectasia Total Deviation Index (AUC = 0.981 and 0.922). When SD-OCT and air-puff tonometry data were combined, the random forest AI model provided the highest accuracy with 99% AUC for FFKC (75% sensitivity; 94.74% specificity).

Currently, AI parameters accurately diagnose AKC and EKC, but have a limited ability to diagnose FFKC. AI-assisted diagnostic technology that uses both SD-OCT and air-puff tonometry may overcome this limitation, leading to improved treatment of patients with keratoconus. [J Refract Surg. 2022;38(6):374-380.].

Comparative Contralateral Randomized Clinical Trial of Standard (3 mW/cm2) Versus Accelerated (9 mW/cm2) CXL in Patients With Down Syndrome: 3-Year Results.

Refractive Surgery

To compare the long-term results of accelerated corneal cross-linking (CXL) (9 mW/cm2, 10 min) with standard CXL (3 mW/cm2, 30 min) in patients with Down syndrome who had keratoconus.

In this contralateral randomized clinical trial, 27 patients with Down syndrome aged 15.78 ± 2.46 years (range: 10 to 19 years) were enrolled. CXL was performed using the KXL System (Avedro, Inc) under general anesthesia, and patients were followed up for 3 years. The main outcome measure was a change in average keratometry in the 3-mm zone around the steepest point (zonal Kmax-3mm). Secondary outcomes were changes in Corvis ST (Oculus Optikgeräte GmbH) biomechanical parameters and vision, refraction, and corneal tomography measurements.

Mean 3-year changes in zonal Kmax-3mm were not significantly different between the accelerated and standard groups (-0.06 ± 0.75 and -0.35 ± 0.94 diopters [D], respectively, P = .727). Despite the contralateral design of the study, based on most baseline biomechanical indices, corneas in the standard group were weaker before treatment. The standard group also showed significantly fewer 3-year changes in the stress-strain index (-0.11 ± 0.21 vs -0.30 ± 0.32), integrated radius (+0.99 ± 3.48 vs +3.14 ± 2.84), and deformation amplitude ratio-2mm (-1.38 ± 1.33 vs +0.30 ± 1.75) (all P < .0167). Corneal stiffness in the accelerated group was stable for 2 years, and the decline mainly occurred during the third year.

In young patients with Down syndrome who had keratoconus, accelerated and standard CXL showed a similar flattening effect. Standard CXL is better able to maintain corneal stiffness in weaker corneas. With accelerated CXL, despite stable results for 2 years, there was decreased corneal stiffness in the third year. Longer follow-up periods are warranted to study the decreased efficacy on keratoconus progression. [J Refract Surg. 2022;38(6):381-388.].

Efficacy and Safety After Toric Posterior Chamber Implantable Collamer Lens and Toric Iris-Fixated Foldable Phakic Intraocular Lens for Myopic Astigmatism.

Refractive Surgery

To compare visual, refractive, and safety outcomes of toric posterior chamber Implantable Collamer Lens (T-ICL) (STAAR Surgical) and toric iris-fixated foldable phakic intraocular lens (IOL) (T-Artiflex; Ophtec BV) implantation for the correction of myopic astigmatism.

This retrospective cohort study included 312 eyes of 312 patients who had phakic IOL implantation for myopic astigmatism. Two groups were defined: 205 eyes that underwent T-ICL implantation and 107 eyes that underwent T-Artiflex implantation. Safety, efficacy, and predictability outcomes were evaluated preoperatively and at 12 months postoperatively. Refractive and corneal astigmatic vector analysis were performed using the Alpins method.

One year postoperatively, uncorrected distance visual acuity was 0.05 ± 0.18 (T-ICL) and 0.10 ± 0.16 (T-Artiflex) logMAR, with efficacy indexes of 1.16 ± 0.27 and 1.05 ± 0.31, respectively (P < .001). Safety indexes were 1.28 ± 0.30 and 1.21 ± 0.31, respectively (P = .04). Spherical equivalent was within ±0.50 diopters (D) of emmetropia in 165 (80.5%) and 88 (82.2%) eyes, respectively. Refractive astigmatic analysis showed an index of success of 0.28 ± 0.33 (T-ICL) and 0.31 ± 0.26 (T-Artiflex) (P = .07). Surgically induced corneal astigmatism was 0.48 ± 0.74 and 0.81 ± 0.61 D, respectively (P < .001). Mean endothelial loss was 1.11% and 2.05%, respectively (P = .42). Six (2.9%) eyes in the T-ICL group and 1 (0.9%) eye in the T-Artiflex group had phakic IOL repositioning due to significant misalignment. No vision-threatening complications occurred.

Both the T-ICL and T-Artiflex groups showed high visual and refractive efficacy with a good safety profile for the correction of myopic astigmatism. T-ICL implantation demonstrated significantly better efficacy and safety indexes after 12 months. Vector analysis showed similar refractive astigmatic correction in both groups, but T-Artiflex implantation revealed higher surgically induced corneal astigmatism. [J Refract Surg. 2022;38(6):339-347.].