Corneal backward scattering and higher-order aberrations in children with vernal keratoconjunctivitis and normal topography

Association of myopia and astigmatism with postoperative ocular high order aberration after small incision lenticule extraction

OBJECTIVE

To investigate the correlation between higher-order aberrations (HOA) after small incision lenticule extraction (SMILE) and the severity of myopia and astigmatism, along with the relevant factors. These findings will provide valuable insights for decreasing the occurrence of HOA after SMILE and enhancing visual quality.

METHODS

A total of 75 patients (150 eyes) with myopia and astigmatism who underwent SMILE were categorized into four groups based on the severity of myopia and astigmatism: Myopia Group 1 (Group M1, spherical diopter ranged from -1.00 D to -4.00 D), Myopia Group 2 (Group M2, spherical diopter ranged from -4.10 D to -10.00 D), Astigmatism Group 1 (Group A1, cylindrical diopter ranged from 0 D to -1.00 D), and Astigmatism Group 2 (Group A2, cylindrical diopter ranged from -1.10 D to -3.00 D). A comprehensive assessment was performed to examine the association between HOA and various relevant factors, including a detailed analysis of the subgroups.

RESULTS

Group M1 had significantly lower levels of total eye coma aberration (CA), corneal total HOA (tHOA), internal tHOA, and vertical CA ( Z 3 - 1 ) after SMILE than Group M2 (P < 0.05). Similarly, Group A1 had significantly lower levels of total eye tHOA, CA, trefoil aberration (TA), corneal tHOA, TA, and vertical TA ( Z 3 - 3 ) after SMILE than Group A2 (P < 0.05). Pearson correlation analysis indicated a statistically significant positive relationship between the severity of myopia/astigmatism and most HOA (P < 0.05). Subgroup evaluations demonstrated a notable increase in postoperative HOA associated with myopia and astigmatism in Groups M2 and A2 compared with the control group. Lenticule thickness, postoperative central corneal thickness (CCT), postoperative uncorrected distance visual acuity (UDVA), and postoperative corneal Km and Cyl were strongly correlated with most HOA. Age, eyes, and postoperative intraocular pressure (IOP) were only associated with specific HOA.

CONCLUSION

HOA positively correlated with the severity of myopia and astigmatism after SMILE. However, this relationship was not linear. HOA after SMILE was influenced by various factors, and additional specialized investigations are required to establish its clinical importance.

The visual impact of higher-order aberrations in patients with pediatric blepharokeratoconjunctivitis

PURPOSE

To analyze higher-order aberrations (HOAs) and their visual impact in a pediatric blepharokeratoconjunctivitis (PBKC) cohort compared with healthy controls.

METHODS

Prospective case-control study of pediatric patients (≤ 16 years old). Subjects underwent wavefront aberrometry analysis to compare HOAs and their impact on visual quality.

RESULTS

A total of 150 eyes from 76 patients were included in the analysis. The PBKC group consisted of 50 eyes and the control group of 100 healthy eyes. Mean age was 10.39 ± 3.81 years for the PBKC group and 10.80 ± 3.61 years for the controls. Mean corrected-distance visual acuity (CDVA) was 0.24 ± 0.21 logMAR in the PBKC group and 0.07 ± 0.1 in the controls (P < 0.001). Mean astigmatism was 1.6 ± 1.98D in the PBKC group vs. 0.67 ± 0.76D in the control group (P = 0.01). Mean RMS of HOAs was 1.05 ± 1.7mm in the PBKC group and 0.41 ± 0.18mm in the controls (P < 0.001). The mean modulation transfer function (MTF) in the PBKC group was significantly lower (16.37 ± 16.32) than controls (30.3 ± 23.57) (P < 0.001). Corneal leukomas, stromal vascularization, peripheral nummular subepithelial scars, and pannus formation are associated with increased HOAs.

CONCLUSIONS

There was a significant increase in total HOAs of eyes with PBKC compared to healthy controls. Corneal opacity, vascularization, and scarring are associated with increased HOAs. The PBKC eye aberration profile: coma, secondary astigmatism, quadrafoil, and pentafoil, were associated with decreased CDVA and visual quality (PSF and MTF).

Corneal topometric indices and proclivity toward corneal ectasia in vernal keratoconjunctivitis

PURPOSE

To investigate changes in topometric corneal indices and proclivity toward corneal ectasia, as well as keratometric indices and anterior chamber dimensions in palpebral vernal keratoconjunctivitis (VKC).

METHODS

This study included 80 patients with clinically established symptoms of grade 0 or grade 1 palpebral VKC (group 1) and 66 healthy participants (group 2). After a comprehensive ophthalmic examination including best-corrected visual acuity, intraocular pressure measurements and slit-lamp biomicroscopy, pachymetric indices and anterior chamber dimensions were measured using the Pentacam HR rotating Scheimpflug device. Topometric indices, which are particularly useful for determining proclivity toward corneal ectasia, were extracted from a topometric map.

RESULTS

In groups 1 and 2, the mean ages were 13.11±5.22 and 16.45±5.09 years, respectively. The mean age at disease onset in group 1 was 10.09±5.03 years, and the mean disease duration was 36.23±8.43 months. Group 1 had significantly higher mean topometric indices than group 2, particularly the index of surface variance (P=0.001), index of vertical asymmetry (P=0.007), center keratoconus index (P=0.050), and Belin/Ambrosio enhanced ectasia total deviation value (P=0.032). Mean posterior corneal astigmatism differed significantly between groups 1 and 2 (P=0.003).

CONCLUSIONS

Significantly higher mean topometric indices in VKC indicate a proclivity for corneal ectasia, which could be attributed to general changes in the corneal ultrastructure caused by persistent itching-induced eye rubbing.

Evaluation of the effects of strabismus surgery on corneal backward light scattering

BACKGROUND

Investigation of the effects of conventional strabismus surgeries on corneal densitometry (CD).

METHODS

Patients who had strabismus surgery between May 2022 and July 2022 were included in the study. CD software with a Pentacam device was used to determine corneal backward light scattering. CD data were analysed preoperatively and 1 month postoperatively. Patients were classified as those who had single muscle and two-muscle surgery.

RESULTS

The study included 33 eyes of 28 patients. The mean age of the patients was 20.51 ± 8.22 (5-35) years. Of the eyes, 19 underwent single muscle recession surgery. Two-muscle surgeries (recession and resection combination) were performed in 14 eyes. In the 1st month postoperative, the mean CD value decreased statistically significantly only in the total cornea apical 0-2 mm zone among the layers examined (p = 0.039). There was no significant change in the other layers (p > 0.05 for all). Single-muscle and two-muscle surgery groups were similar in the amount of CD reduction, except for one layer.

CONCLUSIONS

CD did not change in most of the corneal layers examined in the first month postoperatively. Single muscle and two-muscle horizontal rectus surgeries did not impair corneal clarity in the postoperative 1st month.

Examination of corneal microstructure in the quiescent phase of vernal keratoconjunctivitis using in vivo confocal microscopy

INTRODUCTION

This study investigated the morphological characteristics of corneal microstructure in the quiescent phase of vernal keratoconjunctivitis (VKC).

METHODS

Twenty patients with quiescent VKC and 25 healthy subjects were included. In vivo confocal microscopy (IVCM) of the central cornea was performed. Cellular density of each layer and the morphology of subbasal nerve plexus (SBNP) was analysed. Langerhans cell density (LCD), morphology (LCM), and field area (LCF) were also examined.

RESULTS

No differences were found either in cell densities nor in SBNP morphology (p > 0.05). LCD, LCM and LCF were significantly higher in the VKC group (p = 0.005, p < 0.001 and p < 0.001, respectively). The severity of papillary hypertrophy had a significant impact on LCD, LCM and LCF (β-coefficient: 19.541, p < 0.001; β-coefficient: 0.283, p < 0.001 and β-coefficient: 595.255, p < 0.001, respectively).

DISCUSSION

In quiescent VKC, LCD, LCM, and LCF were increased, and they were associated with the severity of papillary hypertrophy. Alterations of Langerhans cells indicate a subclinical inflammatory process without ocular symptoms.

Safety of EVO ICL Implantation With an Ophthalmic Viscosurgical Device-Free Technique in the Early 24 h After Surgery

Purpose: To compare the safety of the non-ophthalmic viscosurgical device (OVD) technique with that of the minimum OVD technique in EVO Implantable Collamer Lens (EVO-ICL) implantation.

Methods: A total of 180 eyes of 90 consecutive patients were enrolled in the study, of which 100 eyes of 50 patients were treated with non-OVD technique, with a 55% success rate. The remaining 80 eyes of 40 patients were treated with min-OVD technique, so they were classified into the min-OVD group. Preoperative and postoperative intraocular pressure (IOP) measurements were collected and analyzed at 1, 2, 3, and 24 h. Visual acuity, corneal endothelial cell density (ECD), and corneal densitometry 24 h postoperatively were evaluated.

Results: No significant difference was found in visual outcomes (P = 0.54) or ECD (P = 0.78) between the two groups. The operation time was significantly shorter in the non-OVD group (P < 0.0001). The IOP was significantly higher at 1 h (P < 0.0001), 2 h (P < 0.0001) and 3 h (P = 0.0045) postoperatively in the min-OVD group. The non-OVD group had significantly lower IOP than the min-OVD group at 1 h (P = 0.01) and 2 h (P = 0.013) postoperatively. The temporal corneal densitometry in the non-OVD group were significantly lower than those in the minimum group (P = 0.0063) 1 day after surgery.

Conclusion: The non-OVD technique is safe and efficient for ICL implantation. It can be a safer method of ICL implantation in that it completely eliminates ophthalmic viscoelastic devices related complications without causing additional complications in short term.

Corneal biomechanical changes in allergic conjunctivitis

Background

To explore corneal biomechanical changes, identify related factors and determine early indicators of keratoconus (KC) development risk in allergic conjunctivitis (AC) patients.

Methods

A total of 50 patients, including 20 eyes without AC and 30 eyes with AC were enrolled in this study. All patients underwent a complete ocular examination, including evaluations of clinical manifestations of AC, corneal tomography and densitometry by Pentacam, corneal biomechanics by Corvis ST, and corneal and epithelial thickness mapping by RTvue optical coherence tomography (OCT).

Results

The index of surface variance (ISV), index of vertical asymmetry (IVA), keratoconus index (KI), index of height decentration (IHD) and Belin/Ambrosio enhanced ectasia total deviation index (BAD-D) were significantly higher in the AC group than in the non-allergic conjunctivitis (NAC) group (P < 0.05). The tomography and biomechanical index (TBI) was also significantly higher in the AC group (P = 0.04). The average epithelial thickness in the 2–7 mm annulus was significantly thinner in the AC group than in the NAC group (P < 0.05). The average densitometry of the total cornea and the anterior layer were higher in the AC group than in the NAC group (P < 0.001). The ISV, IVA, KI, IHD and BAD-D were significantly correlated with the TBI and changes in corneal epithelial thickness in AC patients (P < 0.05). The changes in epithelial thickness were closely related to the eye rubbing frequency and allergic sign scores (P < 0.05).

Conclusions

AC patients should be advised to routinely undergo corneal tomographic and biomechanical measurements, and the TBI could be used as an indicator of KC development risk in AC patients.

Trial registration

Corneal Biomechanical Changes of Allergic Conjunctivitis, NCT04299399. Registered March 3, 2020 - Retrospectively registered.

Corneal Densitometry After Small Incision Lenticule Extraction (SMILE) and Femtosecond Laser-Assisted LASIK (FS-LASIK): 5-Year Prospective Comparative Study

Purpose: To investigate long-term changes in corneal densitometry (CD) following small incision lenticule extraction (SMILE) vs. femtosecond laser-assisted LASIK (FS-LASIK) in patients with myopia or myopic astigmatism.

Methods: Prospective analysis was performed in 66 eyes of 38 patients (13 males) who underwent SMILE and 54 eyes of 29 patients (5 males) who underwent FS-LASIK. In all patients, an ocular examination was performed preoperatively, and at 6–12 months and 5 years postoperatively. CD was obtained with the Pentacam Scheimpflug imaging system at the 0–2-mm, 2–6-mm, and 6–10-mm zones of the cornea at depth of anterior 120 μm, midcornea, and posterior 60 μm. Correlation analysis was performed between postoperative change in CD and other variables such as age, type of surgery, central corneal thickness, spherical equivalent, lenticule thickness/ablation depth, and changes in wavefront aberrations.

Results: At postoperative 6–12 months, a significant reduction at several corneal zones in the FS-LASIK cohort (P < 0.05) was observed. In the SMILE cohort, no significant change in CD relative to baseline was observed. However, at 5 years postoperatively, in both groups, a significant decrease in CD was observed in three zones of three layers (all P < 0.001). The change in CD was similar between groups at postoperative 6–12 months, but at 5 years the magnitude of change was significantly smaller in SMILE than FS-LASIK in the anterior and central layers (all P < 0.05).

Conclusion: CD with the Scheimpflug imaging system showed a significant decrease at 5 years after SMILE or FS-LASIK, and the change was significantly less pronounced after SMILE.

Characteristics of corneal high-order aberrations in adolescents with mild to moderate myopia

Background

This study investigated the characteristics of corneal higher-order aberrations (HOAs) of the anterior surface, posterior surface, and total cornea in adolescents with mild to moderate myopia.

Methods

A total of 183 patients with myopia (183 eyes) aged 8 to 18 years were enrolled in this study. The axial length (AL) of the eyes was measured by an IOL-Master, and corneal curvatures (K-values) and HOAs were measured by a Pentacam anterior segment diagnostic analyzer.

Results

Results of this study showed that the anterior, posterior and total corneal horizontal coma Z₃¹ were − 0.1249 ± 0.105 μm, 0.0009 ± 0.001 μm, and − 0.1331 ± 0.116 μm, respectively; the anterior, posterior and total corneal vertical coma Z₃^− 1 were − 0.0212 ± 0.164 μm, 0.0003 ± 0.043 μm, and − 0.0216 ± 0.168 μm, respectively; and spherical aberration (SA) Z₄⁰ values were 0.2244 ± 0.091 μm, 0.1437 ± 0.029 um, and 0.1889 ± 0.090 μm, respectively. Total corneal Z₃¹ was statistically correlated with posterior corneal astigmatism (K₂b − K₁b) (p = 0.038). Total corneal Z₃^− 1 was correlated with anterior corneal astigmatism (K₂f − K₁f) (p = 0.027). Anterior, posterior, and total corneal Z₄⁰ were correlated with anterior and posterior corneal curvature (K₁f, K₂f, K₁b, K₂b) (p = 0.001). Posterior corneal Z₄⁰b was also significantly correlated with AL.

Conclusions

In adolescents with mild to moderate myopia, the posterior corneal surface shape may play a compensatory role in the balance of corneal aberrations, and the posterior corneal SA tended to become less negative as the AL increased. The corneal coma may also play a compensatory role in posterior corneal surface astigmatism, which was valuable for the treatment for improving visual quality. This conclusion still needs to be verified.

Unique corneal tomography features of allergic eye disease identified by OCT imaging and artificial intelligence

The purpose of this study was to assess unique corneal tomographic parameters of allergic eye disease (AED) using optical coherence tomography (OCT) and artificial intelligence (AI). A total of 57 eyes diagnosed with AED were included. The curvature and aberrations of the air-epithelium (A-E) and epithelium-Bowman's layer (E-B) interfaces were calculated. Random forest AI models were built combing this data with the parameters of healthy, forme fruste keratoconus (FFKC) and KC eyes. The AI models were cross-validated with 3-fold random sampling. Each model was limited to 10 trees. The AI model incorporating both A-E and E-B parameters provided the best classification of AED eyes (area under the curve = 0.958, sensitivity = 80.7%, specificity = 98.5%, precision = 88.2%). Further, the E-B interface parameters provided the highest information gain in the AI model. A few AED eyes (n = 9) had tomography parameters similar to FFKC and KC eyes and may be at risk of progression to KC.

Corneal and lens densitometry with Pentacam HR in children with vernal keratoconjunctivitis

CLINICAL RELEVANCE

Corneal and lens densitometry measurements provide clinically important information for the evaluation and monitoring of corneal and lens health in patients with vernal keratoconjunctivitis.

BACKGROUND

To compare the corneal and lens densitometry values between paediatric patients with vernal keratoconjunctivitis (VKC) and healthy individuals.

METHODS

This study included 72 eyes of 72 patients with VKC (25 with mild VKC [Group 1], 22 with moderate VKC [Group 2], and 25 with severe VKC [Group 3]), and 25 eyes of 25 healthy subjects (Group 4). Corneal and lens densitometry values were measured using Pentacam HR as follows: for corneal densitometry in two different corneal zones (0-2 and 2-6-mm) and four different corneal depths (at the total thickness, anterior, central, and posterior layers), and lens densitometry in three different lens zones (Zone 1: 2.0-mm, Zone 2: 4.0-mm, and Zone 3: 6.0-mm).

RESULTS

In the 0-2-mm corneal zone for the total thickness and all three layers, corneal densitometry values in Group 3 were significantly higher than those in Groups 1, 2, and 4 (for all values p < 0.012). There was no significant difference in the mean corneal densitometry values between Groups 1 and 2 (for all values p > 0.05). In these groups, the mean corneal densitometry values were significantly higher than those in Group 4 for the anterior layer in the 0-2 and 2-6-mm corneal zones (for all values p < 0.012). The mean values for Zone 3 and average lens densitometry values in Groups 2 and 3 were significantly higher than those in Group 4 (p = 0.001 and p = 0.001, respectively).

CONCLUSION

The current study showed corneal clarity changes in patients with mild, moderate, and especially severe VKC. An increase in the lens densitometry values was also observed in patients with moderate and severe VKC than in healthy individuals.

Scheimpflug Corneal Densitometry Changes After Trabeculectomy

PURPOSE

To study the possible changes in Scheimpflug corneal densitometry 6 months after mitomycin C-augmented trabeculectomy and to compare these measurements with healthy controls.

METHODS

Corneal densitometry was monitored with the Pentacam HR3 before and 6 months after first-time uncomplicated mitomycin C-augmented trabeculectomy in 42 eyes of 42 white patients with open-angle glaucoma and in 22 healthy age-matched controls. Preoperative intraocular pressure (IOP), central corneal thickness, known duration of the disease, gender, the type and number of substances, applications and amount of benzalkonium chloride per day, and postoperative topical cortisone use were tested for possible correlations in the trabeculectomy group.

RESULTS

There was a statistically significant reduction of mean diurnal IOP from 19.0 ± 7.7 to 11.1 ± 7.7 mm Hg (P = 0.003) and the amount of pressure-lowering substances from 3.7 ± 1.0 to 0.1 ± 0.5 (P < 0.001). Densitometry measurements decreased in the entire cornea from 25.5 ± 5.7 to 23.1 ± 5.8 grayscale units (P = 0.001) with emphasis in the anterior layer. They returned close to normal 6 months after trabeculectomy and were not statistically significantly different compared with a healthy control group (22.8 ± 3.4 grayscale unit; P = 0.824). No correlations could be found with these observations and possible causing factors studied.

CONCLUSIONS

Corneal densitometry, an objective and sensitive measure of corneal transparency, returned close to normal 6 months after trabeculectomy. Although the observations cannot be associated with any causing factor in this study, the significant IOP reduction and the nearly complete cessation of topical antiglaucomatous substances including benzalkonium chloride seem to be the most plausible reasons for this finding.

One-year natural course of corneal densitometry in high myopic patients after implantation of an implantable collamer lens (model V4c)

BACKGROUND

Corneal densitometry, which is also known as corneal backscattering, is a surrogate measure of corneal clarity. The purpose of the study was to investigate the changes in corneal densitometry (CD) after implanting an implantable collamer lens (ICL-V4c).

METHOD

Twenty-six high myopic patients (aged 29.3 ± 6.6 years, 6 males and 20 females) who underwent ICL-V4c implantation were enrolled. Intraocular pressure (IOP), corneal topography, corneal densitometry, uncorrected distance visual acuity (UCDVA), manifest refraction, and best corrected distance visual acuity (BCDVA) were evaluated pre-operatively and at 1 day, 1 week, and 1, 3, 6, and 12 months post-operatively. Endothelial cell density (ECD) was measured pre-operatively and at 3, 6, and 12 months post-operatively. The efficacy index (mean post-operative UCDVA / mean pre-operative BCDVA) and the safety index (mean post-operative BCDVA / mean pre-operative BCDVA) were evaluated at 1 month, 3 months, 6 months and 12 months post-operatively.

RESULTS

Over the annular diameters of 0-2 mm, the pre-operative densitometry values of the anterior layer, central layer, posterior layer, and total layer were 20.1 ± 2.8, 11.8 ± 1.1, 10.5 ± 0.9 and 14.1 ± 1.5, respectively. From pre-operatively to post-operative Month 12, the values changed insignificantly (P = 0.177, P = 0.153, P = 0.543 and P = 0.207, respectively). Over the annular diameters of 2-6 mm, the pre-operative mean densitometry values were 17.9 ± 2.2, 10.5 ± 0.9, and 12.6 ± 1.2, respectively. From pre-operatively to post-operative Month 12, the values decreased to 16.5 ± 2.1, 10.0 ± 0.9, and 11.9 ± 1.2, respectively, which were similar to the pre-operative values (all P > 0.05) but significantly lower than the values obtained at post-operative Day 1 (P = 0.013, P = 0.002 and P = 0.010, respectively). The densitometry value of the posterior layer over the annular diameters of 2 to 6 mm remained unchanged (from 9.4 ± 0.7 to 9.1 ± 0.7) over time (P = 0.372). The efficacy and safety indices assessed at 12 months post-operatively were 1.04 ± 0.27 and 1.19 ± 0.23, respectively. The changes in IOP and ECD values were statistically insignificant (P = 0.896 and P = 0.968, respectively).

CONCLUSION

ICL-V4c implantation may be safe and efficient for high ametropia correction. The corneal densitometry values obtained over the annulus of 0-6 mm increased slightly from before the operation to post-operative Day 1 and then decreased gradually, which indicates that ICL-V4c implantation may not compromise corneal clarity.

Drug delivery systems and novel formulations to improve treatment of rare corneal disease

As the field of ocular drug delivery grows so does the potential for novel drug discovery or reformulation in lesser-known diseases of the eye. In particular, rare corneal diseases are an interesting area of research because drug delivery is limited to the outermost tissue of the eye. This review will highlight the opportunities and challenges of drug reformulation and alternative treatment approaches for rare corneal diseases. The barriers to effective drug delivery and proposed solutions in development will be discussed along with an overview of corneal rare disease resources, their current treatments and ophthalmic drug delivery systems that could benefit such cases. The regulatory considerations for effective translation of orphan-designated products will also be discussed.