Epithelial healing in the second eye after corneal abrasion

The influence of lens conditioning on signs and symptoms with new hydrogel contact lenses

BACKGROUND

Daily disposable contact lenses are considered to be the pinnacle of safe contact lens wear, yet it has been suggested that it takes some period of wear for the lens surface to reach optimal compatibility with the ocular surface. This study assesses the influence of brief treatment with a conditioning drop on the ocular response to new contact lenses over a single day of wear.

METHODS

The study was a single-masked, paired (contralateral) comparison of the signs and symptoms with wear of new Acuvue 2 contact lenses pretreated with a conditioning agent containing carboxymethylcellulose (carmellose, CMC) against new lenses inserted directly from the blister pack. Sixty-one subjects participated in the study, of whom 59 were considered eligible for data analysis. Subjects were also divided into symptomatic and asymptomatic lens wearers based on their overall comfort level in lens wear. Symptoms and signs were recorded at lens delivery and following eight hours of wear.

RESULTS

A set of slitlamp signs, comprising corneal staining (p <0.05), limbal redness (p <0.05), bulbar conjunctival hyperaemia (p <0.05), bulbar conjunctival staining (p <0.01) and palpebral conjunctival redness (p <0.05) showed small but statistically significant (p <0.05) end-of-day mean values in favour of the lens that was conditioned with the rewetting agent. These data were supported by the proportion of subjects showing lower gradings with conditioned lenses versus unconditioned lenses, as follows: corneal staining (35 per cent versus 12 per cent, p <0.05), limbal redness (43 per cent versus 22 per cent, p <0.05), bulbar conjunctival hyperaemia (50 per cent versus 15 per cent, p <0.05), bulbar conjunctival staining (46 per cent versus 30 per cent, p <0.1) and palpebral conjunctival hyperaemia (28 per cent versus 17 per cent, NS). For those subjects reporting symptoms with lens wear (n=12), there was a statistically significant (p <0.05) preference in terms of comfort as a result of preconditioning.

CONCLUSIONS

The results of the investigation suggest that use of a conditioning agent can provide a more physiologically suitable environment for a new lens, thereby reducing the clinical signs associated with lens discomfort. The protocol used here, which is based on a statistical paradigm using standard pictorial grading scales, allows high sensitivity in detecting small changes in ocular parameters.

Difference in Outcomes between First-Operated vs. Fellow-Operated Eyes in Patients Undergoing Bilateral Trabeculectomies

MAIN OBJECTIVE

To compare the course and outcome of first- and fellow-operated eyes in patients who underwent bilateral trabeculectomies and to investigate the factors associated with the difference.

METHODS

Preoperative characteristics, including the interval between surgeries, were compared between the first- and fellow-operated eyes in 42 patients who underwent bilateral trabeculectomies. Postoperative intraocular pressure and bleb vascularity, using postoperative anterior segment photos, were compared at various time points between the first- and fellow-operated eyes. Surgical success was evaluated at 1 year after surgery and at the final follow-up. Factors affecting the difference between the first and fellow eyes were analyzed.

RESULTS

There was no significant difference in success or failure rates at 1 year postoperatively and at the final follow-up between the first- and fellow-operated eyes. Early postoperative IOP and the degree of bleb vascularity were higher in the fellow-operated eyes (P = 0.001 and 0.003, respectively at week 1 postoperative). The difference in IOP between the first- and fellow-operated eyes was greater in patients whose interval between surgeries was shorter than 3 weeks (P = 0.026).

CONCLUSIONS

In patients undergoing bilateral trabeculectomies, early postoperative IOP was higher in the fellow-operated eyes than the first-operated eyes; the difference was greater when the interval between surgeries was shorter. The first-operated eye may influence the early postoperative inflammatory response in the fellow-operated eye. Our findings have clinical implications for planning treatment of patients who may need bilateral surgery.

Identical excimer laser PTK treatments in rabbits result in two distinct haze responses

PURPOSE

To obtain objective light-scattering measurements to test a hypothesis that identical PTK treatments cause distinct low- and high-level light-scattering responses in rabbit corneas.

METHODS

An excimer laser was used to produce identical 6-mm diameter phototherapeutic keratectomy treatments (PTK) in 32 pigmented rabbits. Eyes were treated by performing a 40-microm epithelial ablation, followed by a 100-mum stromal PTK. Objective scattering measurements were made before treatment, weekly up to 5 weeks, and then biweekly to 9 weeks. Confocal microscopy was performed on several corneas at 4 and 7 weeks.

RESULTS

Mean scattering levels split into distinct low- and high-scattering groups 2 weeks after treatment and remained distinct until week 7 (P < 0.003). Scattering in the low group reached a broad peak that lasted from weeks 2 to 4 at approximately 3 times the pretreatment level. Scattering in the high group peaked at 3 weeks at approximately 12 times the pretreatment level. Scattering levels diminished after reaching their peaks. Confocal images showed a band of highly reflective material in the anterior stroma that extended much deeper in corneas from the high group. The reflective band in the highly scattering corneas obscured the posterior stroma from view for up to 5 weeks.

CONCLUSIONS

Quantitative scattering data obtained with the scatterometer suggest that identical PTK treatments indeed result in distinct low- and high-level light-scattering responses in rabbits.

Correlation of visual and refractive outcomes between eyes after same-session bilateral laser in situ keratomileusis surgery

PURPOSE

To determine whether between-eye refractive and visual outcomes after same-session laser in situ keratomileusis (LASIK) surgery are correlated, and to determine whether suboptimal visual and refractive outcomes in one eye are predictive of poor results in the fellow eye.

DESIGN

Observational case series.

METHODS

Retrospective chart review. A total of 484 eyes of 242 patients met inclusion criteria of having undergone same-day LASIK surgery and having 3-month refractive and visual acuity outcomes. Statistical comparisons of outcomes were performed, including between-eye Pearson correlation analysis and logistic regression models for predicting second-eye outcome. Main outcome measures were 1-month, 3-month, and 6-month uncorrected visual acuity and manifest refraction.

RESULTS

Refractive outcomes at 1, 3, and 6 months between first (right) and second eyes were not found to be significantly different. No difference in uncorrected or best spectacle-corrected visual acuity was observed between first and second eyes Refractive outcomes of spherical equivalent, sphere, and cylinder and visual outcomes of uncorrected and best spectacle-corrected visual acuity were highly correlated between the two eyes. Analysis of cases with suboptimal outcomes (> or =1 diopter from intended correction or uncorrected acuity equal to or worse than 20/40) suggests that a poor refractive or visual outcome in the first eye increases the risk of a poor outcome in the second eye by approximately 20-fold.

CONCLUSIONS

Retrospective analysis of refractive and visual outcomes from patients undergoing same-session bilateral LASIK demonstrates a high correlation of refractive and visual outcome between the eyes.

A previous abrasion in the contralateral eye influences the cell kinetics during healing of a central corneal abrasion

PURPOSE

To study the influence of a previous erosion in the fellow eye on the proliferative response during healing of a central corneal erosion.

METHODS

A corneal abrasion was made on the right eye of 20 rats. After 1 week a corneal erosion was made in the left eye of the pre-treated animals and in 20 previously untreated animals. Cell kinetic methods were used to estimate the labelling index (LI) and the mitotic rate (MR) after 1, 2, 4, 6 and 12 days.

RESULTS

After 24 hours the corneal erosions were covered by epithelial cells in 3 of 4 animals in both groups. The LI and the MR were significantly higher in the pre-treated group on the 2nd day after erosion.

CONCLUSIONS

The proliferation measured by LI and MR was increased when an abrasion was made in the contralateral eye 1 week earlier. This might explain the faster healing rate of the second eye reported by other authors (Rask et al. 1996). The healing process in the cornea is modulated by systemic influence.

The effect of early steroid treatment after PRK on clinical and refractive outcomes

PURPOSE

To evaluate the effects of steroid treatment administered in the first days after excimer laser keratectomy (PRK) on re-epithelialization time, postoperative pain, haze and refractive outcome.

METHODS

A randomised, double masked trial was carried out on two groups of patients (40 patients each), who underwent PRK. Group A (steroid group) received 0.1% fluorometholone acetate whereas group B (NSAID group) received 0.5% ketorolac tromethamine until re-epithelialization was completed. Subsequently, all 80 patients received the same steroid treatment: 0.1%, fluorometholone acetate for myopic corrections up to -5 D, or dexamethasone for myopic corrections exceeding -5 D. Both drugs were tapered off over approximately 3 months. Follow-up examinations were planned at 1, 3, 6, 12 months after surgery.

RESULTS

Re-epithelialization was completed after three days, without any significant difference between groups. A higher hyperopic shift was shown in the steroid group and a more severe regression was reported in the NSAID group (p<0.001). Haze was significantly reduced in the steroid group (p=0.005), especially for myopic corrections over -5 D (p=0.015). Pain was significantly reduced in the NSAID group (p=0.002).

CONCLUSION

Steroid eyedrops administered in the first days after PRK did not affect re-epithelialization time. Moreover, a modulation of the inflammatory response in this period appears to reduce haze and myopic regression in high myopic patients.

Effect of topical administration of epidermal growth factor on healing of corneal epithelial defects in horses

OBJECTIVE-To characterize healing of corneal epithelial defects in horses and to evaluate the ability of epidermal growth factor (EGF) to modulate rate of corneal epithelial healing in horses.

SAMPLE POPULATION

20 eyes in 12 adult horses.

PROCEDURE

Corneal epithelial wounds were created by mechanically debriding the limbus. Corneal healing was recorded for 3 treatment groups: 50 microg of EGF/ml (n = 5 eyes), 5 microg of EGF/ml (7), and PBS solution (8). Corneal healing was recorded once daily after instillation of fluorescein stain by use of photography and calculating the area of the wound, using imaging software.

RESULTS

After corneal debridement, re-epithelialization was rapid and progressed in a linear fashion for the first 5 to 7 days after surgery in all groups. After that period, rates of healing decreased. A profound increase in the degree of inflammation, neovascularization, melanosis, and scarring was observed in eyes treated with the high dose of EGF (50 microg/ml), but there was not a statistical difference in mean healing time or in mean decrease in radius during the linear phase between the control and either EGF treatment groups. However, for all 8 horses in which both eyes were debrided, the first eye healed significantly faster than the second eye, regardless of treatment.

CONCLUSIONS AND CLINICAL RELEVANCE

Beneficial effects of topical administration of a high dose of EGF for acceleration of healing of corneal defects in eyes of horses are outweighed by the intensity of the associated inflammatory response.

Cellular dynamics of corneal wound re-epithelialization in the rat. I. Fate of ocular surface epithelial cells synthesizing DNA prior to wounding

The fate of ocular surface epithelial cells in response to injury of the cornea was examined. Corneal epithelial cells were labeled during DNA synthesis with [3H]thymidine 1 h prior to wounding. A 3-mm diameter epithelial defect was made in the center of the rat cornea, with the basement membrane remaining intact. Within 12 h of abrasion, labeled cells were detected in the regenerating surface. At 18 h, there was a 2.7- and 17-fold increase of labeled basal and suprabasal cells, respectively, in the epithelium adjacent to the wound, and at 24 and 30 h there was an excessive number of cell layers (up to 7) at the margin of the abrasion. Re-epithelialization progressed as a gradient of cell layers that became diminished towards the center of the wound. Completion of layers 1, 2, 3, and 4 were recorded at 24, 30, 36, and 72 h, respectively. No changes in the labeling index of the limbus or conjunctiva were noted. These results suggest that processes of centripetal and vertical migration, as well as events related to cell division, in the uninjured corneal surface are not impeded by wounding of the corneal epithelium. However, wound healing appears to require cells with a basal phenotype, presumably because of this cell type's migratory capability.