Alterations in the ocular surface and tear film following keratoplasty

Comparative Evaluation of the Corneal Sensitivity Thresholds between the Novel Non-Contact and Cochet-Bonnet Esthesiometers

PURPOSE

Primarily, to evaluate the repeatability and reproducibility of the new noncontact esthesiometer (NCE) in healthy subjects. Secondarily, the corneal sensitivity threshold measurements of the NCE were compared with those of the Cochet-Bonnet esthesiometer (CBE).

DESIGN

Assessment reliability study.

METHODS

Two examiners measured bilateral corneal sensitivity thresholds by NCE and CBE. Triple NCE measurements were performed per eye at all 5 levels, whereas single CBE measurements were performed per eye. When appropriate, NCE (mBar) and CBE (mm) measurements were converted to millinewtons (mN) for direct comparison between devices. The NCE measurement variations were calculated with the intra-class correlation coefficients (ICC) for the primary objective. For the secondary objective, Bland-Altman plots with 95% limits of agreement (95%-LoA) and Spearman's rank correlation coefficients were used to evaluate the level of agreement and linear relationship between the corneal sensitivity thresholds obtained with both devices. Generalized estimating equation models were used to account for the inter-eye correlation of the same study participant.

RESULTS

Fifty subjects (100 eyes) aged 29 years (median) were included. There were no statistically significant differences in the pressure measured by both observers at each NCE level (all P > .05). There was a high intra-observer and inter-observer repeatability of the NCE measurements (ICC > 0.90) and a strong linear correlation (rho > 0.7) at each NCE level. The difference between the mean corneal sensitivity thresholds (mN) measured with the NCE (0.052 ± 0.021 mN) and CBE (0.046 ± 0.005 mN) was statistically significant (P = .001). Bland-Altman analysis revealed a differential bias of +0.00578 mN (95%-LoA -0.03677 - +0.04833 mN) between threshold measurements.

CONCLUSIONS

The NCE provides reliable user-independent corneal sensitivity measurements. The NCE and CBE do not yield similar values. Thus, both devices cannot be used interchangeably.

Central Corneal Subepithelial Haze Following Keratoplasty With Interrupted Sutures: A Novel Clinical Finding

Purpose

This study aims to describe a newly identified clinical finding of central corneal subepithelial haze following keratoplasty (both penetrating and lamellar) with interrupted sutures, and to explore its causes and management strategies.

Methods

Case series.

Results

The study included 7 males and 3 females, with an average age of 24.89 ± 6.57 years. Eight eyes underwent lamellar keratoplasty, and two underwent penetrating keratoplasty. Subepithelial haze appeared between 2 and 5 months postoperatively, associated with central corneal steepening. The mean BCVA improved from 0.88 ± 0.50 logMAR preoperatively to 0.51 ± 0.20 at haze documentation and 0.50 ± 0.16 after haze resolution. Selective suture removal resulted in haze resolution in 9 eyes, while delayed intervention in one case led to permanent scarring.

Conclusion

Central corneal subepithelial haze following keratoplasty with interrupted sutures is linked to suture tension and central corneal steepening. Early suture adjustment or removal is essential to prevent permanent scarring. Further studies are needed to better understand this complication's pathophysiology.

Post-Keratoplasty Microbial Keratitis in the Era of Lamellar Transplants-A Comprehensive Review

Microbial keratitis in a post-transplant cornea should be considered a distinct entity from microbial keratitis in a non-transplant cornea. Firstly, the use of immunosuppressive treatments and sutures in corneal transplants changes the etiology of keratitis. Secondly, corneal transplant has an impact on corneal biomechanics and structure, which facilitates the spread of infection. Finally, the emergence of lamellar transplants has introduced a new form of keratitis known as interface keratitis. Given these factors, there is a clear need to update our understanding of and management strategies for microbial keratitis following corneal transplantation, especially in the era of lamellar transplants. To address this, a comprehensive review is provided, covering the incidence, risk factors, causes, and timing of microbial keratitis, as well as both clinical and surgical management approaches for its treatment in cases of penetrating and lamellar corneal transplants.

Main issues in deep anterior lamellar keratoplasty: A systematic narrative review

Deep anterior lamellar keratoplasty (DALK) has emerged as a transformative approach in managing corneal pathologies, notably keratoconus (KC), providing a viable alternative to penetrating keratoplasty (PK). This systematic review explores the intricacies of DALK, comparing its preoperative, intraoperative, and postoperative considerations with PK. Extensive literature searches revealed a wealth of data regarding DALK's advantages and challenges, with an emphasis on graft survival, visual outcomes, and complications. In the preoperative phase, DALK showcases its versatility, catering to a wide spectrum of patients, including those with KC and ocular surface disorders. Intraoperatively, it offers innovative techniques to address emphysema, bubble formation, and Descemet's membrane perforation, all while maintaining a strong focus on patient-centered outcomes. Postoperatively, DALK's lower rejection rates and decreased complications underscore its potential superiority over PK, although unique challenges such as graft failure from nonimmunologic factors demand vigilant management. This comprehensive review not only serves as a valuable resource for ophthalmic surgeons but also sheds light on the evolving landscape of corneal transplantation, highlighting DALK's role as a transformative force in the field.

Visual fatigue a comprehensive review of mechanisms of occurrence, animal model design and nutritional intervention strategies

When the eyes work intensively, it is easy to have eye discomfort such as blurred vision, soreness, dryness, and tearing, that is, visual fatigue. Visual fatigue not only affects work and study efficiency, but long-term visual fatigue can also easily affect physical and mental health. In recent years, with the popularization of electronic products, although it has brought convenience to the office and study, it has also caused more frequent visual fatigue among people who use electronic devices. Moreover, studies have reported that the number of people with visual fatigue is showing a trend of increasing year by year. The range of people involved is also extensive, especially students, people who have been engaged in computer work and fine instruments (such as microscopes) for a long time, and older adults with aging eye function. More and more studies have proposed that supplementation with the proper nutrients can effectively relieve visual fatigue and promote eye health. This review discusses the physiological mechanisms of visual fatigue and the design ideas of animal experiments from the perspective of modern nutritional science. Functional food ingredients with the ability to alleviate visual fatigue are discussed in detail.

A Multicenter Prospective Randomized Controlled Study of a New Corneal Wetting Agent During Ophthalmologic Surgery

INTRODUCTION

A multicenter prospective randomized controlled study was used to investigate the effect and safety of a new corneal wetting agent called the Corneal Surface Viscoelastic Protector (CsVisc, Success Bio-Tech Co., Ltd, China), on the corneal epithelium during ophthalmic surgery by comparison with the commercially available Cornea Protect (CP, Valeant Med Sp. zo. o. Leobendorf, Austria).

METHODS

This multicenter prospective randomized controlled study comprised patients scheduled for cataract surgery and pars plana vitrectomy. The patients were randomly assigned to receive either a new corneal wetting agent (CsVisc) or Cornea Protect (CP, Valeant Med Sp. zo. o. Leobendorf, Austria). Optical clarity during surgery, application frequency, duration of effect, diffusion time of corneal wetting agents, fluorescein staining, intraocular pressure (IOP), tear-film break-up time (TBUT), and Schirmer I test (SIT) were assessed. Adverse events were noted on the designated patient case report forms.

RESULTS

A total of 149 eyes (149 patients, mean age 62 years; range 25-80 years) were included in the study. There were 74 eyes in the control group and 75 eyes in the study group. In patients who underwent vitrectomy, the frequency of application was 1.62 ± 1.03 in the study group and 1.39 ± 0.66 in the control group, with no significant difference (P = 0.399), and the duration of effect was 19.16 ± 6.94 min in the study group and 19.06 ± 7.22 min in the control group, with no significant difference (P = 0.835). The optical clarity of the study group was not significantly different from that of the control group (P = 0.485). In patients who underwent cataract surgery, the frequency of application was 1.10 ± 0.38 in the study group and 1.07 ± 0.26 in the control group, and the difference was not significant (P = 0.950). The difference between the duration of effect in the study group (8.32 ± 2.50 min) and the control group (7.63 ± 2.52 min) was not significant (P = 0.310). The difference in optical clarity scores between the two groups was not statistically significant (P = 0.600). Among all patients in this study, the diffusion time of the corneal wetting agent was 14.97 ± 10.07 s in the control group and 11.23 ± 8.41 s in the study group, with a statistically significant difference (p = 0.008). The frequency of adverse events was 20.00% (15/75) in the study group and 14.86% (11/74) in the control group, with no statistically significant difference (P = 0.409). There were no serious adverse events related to the test medical device or causing patients to withdraw from the study.

CONCLUSIONS

The CsVisc is safe and effective in preventing intraoperative corneal epithelial damage due to corneal dryness and can be comparable to the CP. In addition, the CsVisc has a shorter diffusion time.