Corneal epithelial debridement for diagnosis and therapy of ocular surface disease

Diamond burr debridement of calcific band keratopathy in 24 eyes of 22 horses

PURPOSE

To evaluate the safety and effectiveness of diamond burr debridement (DBD) for the treatment of calcific band keratopathy (CBK) in horses.

METHODS

Medical records from horses with CBK were reviewed over a period of 4 years. Diagnosis of CBK was based on slit-lamp examination findings, and DBD was performed on standing sedated horses. Follow-up was obtained by clinical reevaluation of the treated eyes or a telephone survey with the referring veterinarian.

RESULTS

Twenty-two horses of different ages (median: 11 years; range: 5-23) representing 24 CBK-affected eyes (14 left eyes and 10 right eyes) were included in the study. The patients had a medical history of chronic and recurrent uveitis, which required repeated long-term treatments with various combinations of ophthalmic corticosteroids. DBD alone cleared the cornea in 22 affected eyes (92%), but it was combined with blade scraping in two cases with thick calcium plaques. The postoperative medication included a topical antibiotic, atropine drops, and oral flunixin meglumine. Corneal healing was achieved in 21 eyes (87%), 5-21 days (median time 13 days) postoperatively. The three remaining horses were lost to follow-up. Recurrence occurred in 5 of the 21 (24%) reexamined eyes, 3-12.5 weeks (median 8 weeks) postoperatively, and required a second DBD. Four of the 21 eyes ended up being enucleated due to sequelae of uveitis. The main limitations of the study include those inherent to all retrospective clinical data collections.

CONCLUSION

Mechanical DBD can readily and safely clear the cornea in horses with CBK, but recurrence of calcium deposition is possible.

Low-intensity low-frequency ultrasound mediates riboflavin delivery during corneal crosslinking

We employed the mechanical effect from 40 kHz ultrasound (US) to improve the delivery of riboflavin into corneal stroma for collagen crosslinking, which can benefit the treatment of keratoconus and other corneal ectasias. Experiments were conducted, first with porcine corneas ex vivo and then with New Zealand white rabbits in vivo, at varying mechanical index (MI) and sonication time. Results showed that 15 min of US applied on the cornea at MI = 0.8 in the presence of 0.5% of riboflavin solution enabled its delivery to deeper corneal stroma. Excessive heat was removed by a cooling setup to negate the thermal effect. The corneal absorption amount and penetration of riboflavin through cornea as detected by fluorotron, as well as the enhancement of corneal stiffness as measured by Young's modulus, were comparable to the conventional approach that requires complete corneal epithelium debridement. Histological analysis revealed minor exfoliation of superficial cell layers of corneal epithelium and loss of ZO-1 tight junctions immediately after US. Full recovery of the corneal epithelium and restoration of tight junctions occurred in 3-4 days. The study shows that low-intensity low-frequency ultrasound (LILF US) is a less invasive alternative to the conventional epithelium-off method for delivering riboflavin into the corneal stroma.

Superficial Keratectomy: A Review of Literature

Superficial keratectomy (SK) is the manual dissection of the superficial corneal layers (epithelium, Bowman's layer, and sometimes superficial stroma). SK is done using a surgical blade or diamond burr. Some surgeons use intraoperative mitomycin C 0.02% or amniotic membrane transplantation to improve surgical outcomes. This literature review shows that SK remains an effective method for different indications, including tissue diagnosis, excision of corneal degenerations, dystrophies, scarring, recurrent corneal erosions, and retained corneal foreign body.

Superficial keratectomy: indications and outcomes

INTRODUCTION

To evaluate the indications and outcomes of manual blade superficial keratectomy STUDY DESIGN: Retrospective, nonrandomized, consecutive case series METHODS: Database search of patients from 2012-2017 who underwent superficial keratectomy was conducted at a tertiary care hospital cornea clinic. Charts of 121 patients (156 eyes) were reviewed who had at least 4 weeks of follow-up and both preoperative and postoperative measurements of best-corrected visual acuity or corneal cylinder. Outcome measures included: patient demographics, surgical indication, prior ocular history, best-corrected visual acuity (BCVA) changes, corneal and refractive astigmatism changes, recurrence of pathology, additional treatments required, and intraoperative and postoperative complications.

RESULTS

Mean patient age at time of operation was 63.3 (±14.8), 39% were male. Indications included epithelial basement membrane dystrophy, recurrent corneal erosion syndrome, Salzmann nodular degeneration, band keratopathy, and suspected ocular surface neoplasia. In eyes with epithelial basement membrane dystrophy, mean BCVA (20/47 to 20/40, P = 0.033), refractive astigmatism (1.76 ± 1.83 D to 1.15 ± 1.08 D, P = 0.010), and corneal astigmatism (1.44 ± 0.88 D to 1.06 ± 0.88 D, P = 0.022) significantly improved. Twenty-four percent (5/21) of eyes with recurrent erosions had symptoms return at a mean 6.5 months follow-up. No intraoperative complications were noted. The epithelium healed completely in all 156 eyes at final follow-up.

CONCLUSION

Superficial keratectomy is a simple, safe procedure that can be performed for a variety of conditions to improve visual acuity, reduce corneal astigmatism, and alleviate symptoms secondary to ocular surface pathology.

Clinical efficacy of conjunctival flap surgery in the treatment of refractory fungal keratitis

The aim of the present study was to investigate the use and effectiveness of a selective, partial, pedunculated (tongue-shaped) conjunctival flap (CF) for the treatment of refractory fungal keratitis (FK) with or without perforation. A total of 31 cases of corneal diseases treated by CF surgery between April 2014 and October 2015 were evaluated. Among the 31 cases, 16 cases (male:female, 11:5) with FK were selected. Logistic regression analysis was used to investigate factors associated with complications of CF surgery. A higher prevalence of FK was identified among male farmers compared with female farmers, in which plant trauma was the most prevalent cause of the disease. Only 4 patients had experienced corneal perforation prior to CF surgery. Patients aged 61–80 years had a higher prevalence of FK (50%) compared with other age groups; however, there was no statistically significant correlation between the prevalence of FK and sex or age. It was also demonstrated that age, sex, combined surgery and surgery duration were not significantly associated with post-surgical complications. All CF surgeries were performed following corneal ulcer scraping; however, 4 patients (12.5%) required additional surgery. The visual acuity of participants post-surgery decreased in 4 cases and remained unchanged in 12 cases. A total of 3 study patients experienced post-surgical complications of corneal perforation (1 patient) and purulent exudate spreading (2 patients). The post-surgical outcome was good for all study participants as the surgeries were able to control infection and preserve the eyeball, with the potential of future corneal transplant. These results suggest that CF surgery may be a useful alternative treatment for refractory FK in countries such as China where there is lack of cornea donors.