Validation of IVCM in measuring sub-basal nerve plexus and keratocyte cell density in corneal wound healing

Introduction: This study aimed to evaluate the reliability measurement of corneal stromal thickness, sub-basal nerve plexus (SBNP) and keratocyte cell density (KCD) in laser refractive surgery patients. Methods: 120 eyes of 60 participants were recruited and both right and left eyes of the myopic subjects were measured separately. Cornea stromal thickness were measured based on the cellular morphology that differs between each corneal layer. Measurement of SBNP and KCD were done using in-vivo confocal microscopy (IVCM) using corneal stromal thickness as reference. Corneal nerve parameters measured includes nerve fiber density (NFD), nerve branch Density (NBD) and nerve fiber length (NFL) while KCD were measured based the amount per area, depending on the region of interest. All images were captured and processed using ImageJTM Software and NeuronJ. All data were expressed in mean and standard deviation. Statistical analyses were performed using Predictive analytics software. P < 0.05 was set as the level of significance. Intra- and inter-observer intraclass correlation analysis were done to evaluate reliability of measurement in corneal stromal thickness, SBNP and KCD. Results: This study found no significant difference between measurements for corneal stromal thickness, SBNP and KCD measured. (All P > 0.05). Intraclass correlation analysis showed both intra- and inter-observer performance were approximately consistent and reliable (All r > 0.90, P > 0.05). Conclusion: Measurement of corneal stromal thickness, SBNP and KCD using IVCM is valid and reliable

Immediate effects of artificial tears with and without preservatives containing hyaluronic acid and carboxymethyl cellulose

Background: Currently, hyaluronic acid (HA) and carboxymethyl cellulose sodium (CMC) are common polymers incorporated in artificial tears (ATs). The aim of the present study was to evaluate the immediate effect of preservative- and preservative-free HA- and CMC-containing ATs on tear-film parameters and determine patient preference after AT instillation. Methods: In this prospective, double-blind, randomized, comparative study, we assessed fluorescein tear break-up time (TBUT), bulbar redness, and tear ferning pattern (TFP) up to 60 min after the instillation of ATs with and without preservatives containing HA and CMC in the recruited participants. To test patient preference, each patient was administered with the Ora Calibra™ Ocular Discomfort and 4-Symptom Questionnaire (OOD4SQ; scale of 0–5) before and 60 min after the instillation of ATs. The selection of 14 descriptive words based the 11-point Ora Calibra™ Drop Comfort Scale (ODCS; scale of 0–10) was administered immediately after instillation of each AT to test the drop comfort score. Results: We enrolled 200 eyes of 200 patients, including 163 (81.5%) women and 37 (18.5%) men, with a mean (standard deviation) age of 28.38 (5.42) years. Immediately or 5, 15, or 60 min after the instillation, the mean TBUT did not differ by presence of preservatives, HA, or CMC (all P &gt; 0.05). However, it was significantly higher 5-min post-instillation compared to baseline and significantly lower 15- and 60-min post-instillation (all P &lt; 0.05). The mean grade of bulbar redness immediately or 3, 5, 15, or 60 min after instillation did not differ by presence of preservatives for HA or CMC containing ATs (all P &lt; 0.05). It did not differ significantly 3-, 5-, 15-, or 60-min post-instillation compared to baseline (all P &gt; 0.05). The mean drop comfort scale after the instillation of ATs did not differ significantly by presence of preservatives, HA, or CMC (all P &lt; 0.05). Positive descriptive words were selected by a higher proportion of participants in both groups. According to OOD4SQ, the overall discomfort and mean dryness scores improved significantly after instillation of HA-containing ATs (both P &lt; 0.05), while the mean burning sensation, grittiness, and stinging scores remained unchanged (all P &gt; 0.05). The overall discomfort and mean scores for each ocular symptom (P &lt; 0.05), except for stinting (P &gt; 0.05), improved significantly after instillation of CMC-containing ATs. The TFP did not change significantly from baseline to 60 min after the instillation of any AT (P &gt; 0.05). Conclusions: Both ATs with and without preservatives containing HA and CMC produced positive short-term objective and subjective effects. However, TBUT, TFP, bulbar redness, and patient feedback were comparable for both HA- and CMC-containing ATs. Further trials with longer observation periods or the recruitment of patients with different severities of dry eye could provide more robust and clinically applicable conclusions

Effects of artificial tears on keratocyte cell density after femtosecond laser in situ keratomileusis: a prospective, comparative, interventional, contralateral eye study

Background: Flap creation during laser refractive surgery restructures the anterior cornea, particularly the stroma, reducing the keratocyte cell density (KCD). This reduced density makes it challenging to completely regenerate to the presurgical phase. The aim of the present study was to investigate the effects of two types of artificial tear (AT) interventions on KCD up to 3 months after femtosecond laser-assisted in situ keratomileusis (FS-LASIK) surgery. Methods: This prospective, double-blind, comparative, interventional, contralateral eye study recruited patients with myopia scheduled for FS-LASIK. Inclusion criteria were healthy individuals aged 19 – 25 years with moderate or high myopia, a maximum cylindrical error of - 1.25 diopters, and a maximum pupil size of 6.5 mm who had undergone FS-LASIK and completed 3 months of follow-up. Complete optometric and ophthalmologic examinations were performed. Bilateral simultaneous FS-LASIK surgery was performed using the same femtosecond laser platform as in the standard procedure. The Research Randomizer was used to determine the eye to be treated with Systane® Hydration (Alcon Laboratories, Inc., Fort Worth, TX, USA) or Systane® ULTRA (Alcon Laboratories, Inc., Fort Worth, TX, USA) AT. KCD was examined using real-time images obtained from in vivo confocal microscopy (Heidelberg Retina Tomograph 3 with the Rostock Cornea Module, HRT III RCM); Heidelberg Engineering GmbH, Heidelberg, Germany) at baseline and 1- and 3-month postoperative visits. Results: We included 60 eyes of 30 participants with a mean (standard deviation) age of 21.34 (1.85) years and a male-to-female ratio of 1:1 who completed 3-month post-FS-LASIK surgery follow-up. KCD did not differ significantly between the two groups at any visit (all P &gt; 0.05); nevertheless, mean KCD was initially reduced up to 1 month postoperatively and then revealed a slight increase up to 3 months postoperatively in Systane® Hydration-treated eyes and continued to reduce in Systane® ULTRA-treated eyes. Intragroup comparisons revealed that the eyes treated with ATs experienced a significant reduction in KCD between the preoperative and 1-month postoperative visits and between the preoperative and 3-month postoperative visits (all P &lt; 0.05). Treatment-related complications were not observed. Conclusions: Overall, KCD reduced up to 3 months post-FS-LASIK surgery. Both AT types exerted a comparable effect on postoperative KCD up to 3 months. Future studies with a more frequent administration of ATs, longer follow-up periods, and a control group are required before preliminary outcomes of the present study can be generalized

Association between visual performance and aberration using quality of life impact of refractive correction (QIRC) questionnaire in moderate and high myopic patient

Introduction: This study aimed to evaluate the association between visual performance and aberration using quality of life impact of refractive correction (QIRC) questionnaire in moderate and high myopic groups. Methods: 120 eyes of 60 participants were recruited and both right and left eyes of the myopic subjects were measured separately. For satisfaction in visual performance, Quality of Life Impact of Refractive Correction (QIRC) questionnaire were given to all participants. For aberration measurement, WASCA wavefront analyser were done in dimmed illuminated room. Aberration was recorded as root mean square (RMS). WASCA built-in wavefront analysis computed three best measurements of RMS for third and fourth orders of aberration. The average of three measurements were taken for analysis. All data were expressed in mean and standard deviation. Statistical analyses were performed using Predictive analytics software. P < 0.05 was set as the level of significance. Independent T-test were done to compare all parameters between moderate and high myopia, including QIRC scores. Results: This study found the mean QIRC scores were approximately similar between moderate and high myopia (Both P > 0.05). However, high order aberration (HOA) comprise of third and fourth order aberration were found significantly higher in high myopia group compared to moderate myopia group (Both P < 0.05). Conclusion: This study found that QIRC questionnaire could not be able to differentiate subjective visual performance between moderate and high myopia

Contralateral eye comparison of the efficacy and safety of two artificial tear formulations for corneal subbasal nerve fiber regeneration after photorefractive keratectomy

Background: Currently, artificial tears (ATs) are the first-line agents for managing dry eye disease (DED). This study compared the efficacy and safety of two different AT formulations, Systane® Hydration (SH) and Systane® Ultra (SU), on symptoms of DED and regeneration of the subbasal corneal nerve fiber length (CNFL) in photorefractive keratectomy (PRK)-treated eyes. Methods: This prospective contralateral comparative study recruited myopic eyes scheduled for PRK, and either SH or SU were administered for up to 3 months postoperatively. All participants underwent a standard comprehensive preoperative ophthalmological examination, in vivo confocal microscopy to evaluate the subbasal CNFL, and completed Ocular Surface Disease Index (OSDI) questionnaire for assessing dry eye symptoms. Image analysis software was used to calculate the subbasal CNFL (μm/mm2). Assessments were repeated at the 1- and 3-month follow-up visits. Pre- and postoperative subbasal CNFL and OSDI scores were compared to determine inter- and intra-group differences. Results: Fifty eyes of 25 participants were included in this study. The mean (standard deviation) age of the participants was 22.7 (3.8) years. The OSDI scores for both groups increased significantly at 1 month (both P 0.05). Although OSDI scores were comparable at baseline and at the 1-month postoperative visit (both P> 0.05), the SU-treated eyes had a significantly better OSDI score at the 3-month visit (P 0.05). In both groups, subbasal CNFL was significantly reduced at 1 month, followed by a significant increase at the 3-month postoperative visit compared to baseline (all P< 0.05). No treatment-related complications were observed at the end of the study period. Conclusions: No significant difference was found between the preoperative and 3-month postoperative OSDI scores in the SH- or SU-treated eyes. Subbasal CNFL regeneration indicated a positive effect of both ATs, with a longer mean CNFL noted in the SH-treated eyes at the final visit. This suggests that SH may be a better option for improving corneal reinnervation after PRK. These observations must be verified in further trials with longer follow-up periods and larger sample sizes