The use of acellular porcine corneal stroma xenograft (BioCorneaVet™ ) for the treatment of deep stromal and full thickness corneal defects: A retrospective study of 40 cases (2019-2021)

Pig Models in Retinal Research and Retinal Disease

The pig has been used as a large animal model in biomedical research for many years and its use continues to increase because induced mutations phenocopy several inherited human diseases. In addition, they are continuous breeders, can be propagated by artificial insemination, have large litter sizes (on the order of mice), and can be genetically manipulated using all of the techniques that are currently available in mice. The pioneering work of Petters and colleagues set the stage for the use of the pig as a model of inherited retinal disease. In the last 10 years, the pig has become a model of choice where specific disease-causing mutations that are not phenocopied in rodents need to be studied and therapeutic approaches explored. The pig is not only used for retinal eye disease but also for the study of the cornea and lens. This review attempts to show how broad the use of the pig has become and how it has contributed to the assessment of treatments for eye disease. In the last 10 years, there have been several reviews that included the use of the pig in biomedical research (see body of the review) that included information about retinal disease. None directly discuss the use of the pig as an animal model for retinal diseases, including inherited diseases, where a single genetic mutation has been identified or for multifactorial diseases such as glaucoma and diabetic retinopathy. Although the pig is used to explore diseases of the cornea and lens, this review focuses on how and why the pig, as a large animal model, is useful for research in neural retinal disease and its treatment.

Application of multi-layer porcine small intestinal submucosa for the reconstruction of deep corneal defects in cats

OBJECTIVE

This study documented the application of porcine small intestinal submucosa (SIS) as a stand-alone scaffold for treating deep corneal defects in cats.

METHODS

Medical records of 20 cats with deep stromal ulcers, perforations, or corneal sequestra that underwent surgical treatment with SIS grafts between 2021 and 2022 were retrospectively reviewed. Data on re-epithelialization time, corneal transparency score, and complications were collected to analyze the reconstruction of deep corneal defects after SIS biomaterial implantation.

RESULTS

All cats were unilaterally affected. The corneal defects varied in size, with a median diameter of 8.3 mm (range: 3-15 mm). Re-epithelialization of the SIS graft was completed 16-32 days after surgery (median, 22.3 days). No, mild, or moderate corneal transparency was detected in 90% of the cases. Complications were observed in eight cases (40%), including aqueous leakage (10%), partial SIS malacia (25%), and persistent bullous keratopathy (5%). The follow-up period ranged 90-725 days, with a median duration of 255 days. The SIS graft was successfully applied as a single scaffold in 17 of 20 cases (85%).

CONCLUSION

The results of this study suggest that the application of commercial SIS is an effective surgical technique for managing deep corneal defects in cats.

Hydrodissection to create conjunctival flaps in dogs with corneal ulcers

Background and Aim

Hydrodissection is a liquid injection technique that is rarely used in animal ophthalmic procedures. The use of this technique in the creation of conjunctival flaps for the treatment of corneal ulcers in dogs can improve the outcome, task, and comfort for patients. This study aimed to evaluate the use of hydrodissection in the creation of conjunctival flaps in dogs with corneal ulcers.

Materials and Methods

This study focused on a surgical procedure for creating conjunctival flaps in the eyes of 17 dogs with deep corneal ulcers. We divided the patients into two groups: Hydrodissection was performed in the first group (G1) and conventional divulsion without hydrodissection in the second group (G2). In G1, the conjunctival flap was created by subconjunctival injection of 1 mL of 0.9% sodium chloride, followed by flap construction. The flap was constructed through conventional divulsion using iris scissors in the G2. The operative time, degree of bleeding, and ease of conjunctival divulsion were evaluated during the procedure. Blepharospasm, hyperemia, edema, and scarring of the conjunctiva were evaluated during the post-operative period. Post-operative complications, notably suture dehiscence, were recorded in each group.

Results

Hydrodissection is an easy-to-perform maneuver that optimizes the construction of conjunctival flaps. There were no statistical differences in the parameters used to evaluate the trans- and post-operative period between the groups. The volume of sodium chloride administered in the conjunctiva ranged from 0.5 mL to 1 mL in G1. Dehiscence of the flap sutures was observed in four patients (two in G1 and two in G2), with no significant difference between the groups.

Conclusion

Hydrodissection facilitates the construction of conjunctival flaps in dogs with corneal ulcers, affording greater comfort to patients and proving to be an excellent option for ophthalmologists.

The use of a "horizontal centrifugation protocol" to prepare autologous platelet-rich fibrin membranes for corneal reconstruction surgery in dogs with complicated corneal ulcerations: A case series

OBJECTIVE

The purpose of this case series was to describe the effect of autologous PRF membrane for corneal reconstruction surgery in dogs. PRF membranes made from two healthy dogs unrelated to the current case series were used for PRF histologic analyses.

ANIMALS

Seven dogs with complicated corneal ulcerations.

PROCEDURE

A complete ophthalmic examination, hematology, and fibrinogen analysis were performed pre-surgery. A PRF clot was made from autologous blood in a serum tube after centrifugation in a horizontal Bio-PRF® Centrifuge at 700 × g for 8 min. The PRF clot was processed in a PRF-Box® into a PRF membrane. The PRF membrane was sutured to the corneal ulcer bed. Each dog had a follow-up at days 5-7, 12-14, and 30-40 post-surgery. A final long-term follow-up was performed as well.

RESULTS

A positive outcome with healing and a "good" quality PRF membrane was seen in six out of seven dogs. One dog had a fibrinogen level below normal range and the PRF membrane was of "poor" quality. This dog developed a descemetocele 13 days post-surgery and needed rescue surgery. Mean healing time for all dogs was 9 ± 5.5 days. Minimal scarring, corneal pigmentation, and vascularization were observed at the final long-term follow-up 288 ± 44 days post-surgery.

CONCLUSION

PRF membrane was successful as graft material for corneal ulceration reconstruction surgery. Low fibrinogen appeared to have negative effect on the quality of the PRF membrane, showing the importance for the surgeon to evaluate the quality of the PRF membrane prior to surgery.

An eye on the Shih Tzu dog: Ophthalmic examination findings and ocular surface diagnostics

OBJECTIVE

To characterize the ocular surface parameters and determine the prevalence of ocular pathology in Shih Tzu dogs.

ANIMAL STUDIED

Fifty Shih Tzu dogs (28 male, 22 female).

PROCEDURES

Each dog underwent a complete ophthalmic examination (recording any pathology) and a series of diagnostics, allowing for a 10 min-interval between tests: intraocular pressure (IOP), blink rate, palpebral fissure length (PFL), corneal tactile sensation (CTS), Schirmer tear test, and nasolacrimal reflex without (STT-1, NL-STT1) and with topical anesthesia (STT-2, NL-STT2), tear ferning, strip meniscometry test (SMT), tear film breakup time (TFBUT), and punctate fluorescein staining (PFS) of the cornea.

RESULTS

Mean ± SD test values were as follows: IOP (17.9 ± 3.7 mmHg), blink rate (2.4 ± 1.4 blinks/min), PFL (23.8 ± 1.8 mm), CTS (1.8 ± 0.7 cm), STT-1 (22.0 ± 5.5 mm/min), NL-STT1 (24.2 ± 4.7 mm/min), STT-2 (16.9 ± 6.5 mm/min), NL-STT2 (18.5 ± 7.5 mm/min), SMT (7.5 ± 3.5 mm/5 s), TFBUT (5.3 ± 2.4 s), tear ferning (1.3 ± 0.7), and PFS (1.6 ± 0.6). PFL was significantly greater in male vs. female Shih Tzus (p< .001). Age was negatively correlated with TFBUT results (r = -0.31, p = .027). Lagophthalmos was observed in 82% eyes. Ocular surface pathology was common, including adnexal abnormalities (100% eyes with caruncular trichiasis and medial lower lid entropion) and corneal opacification (27% pigmentation, 20% fibrosis, 12% neovascularization).

CONCLUSIONS

Qualitative tear film deficiency (low TFBUT), along with several anatomical abnormalities that promote ocular irritation and reduce globe protection, together help explain the concerningly high prevalence of ocular surface disease in the Shih Tzu breed. Prophylactic measures (e.g., medial canthoplasty, topical lubrication) could be considered to improve ocular health in Shih Tzus.

Lamellar Keratoplasty Using Acellular Bioengineering Cornea (BioCorneaVetTM) for the Treatment of Feline Corneal Sequestrum: A Retrospective Study of 62 Eyes (2018–2021)

Simple Summary

Corneal sequestrum is a specific and common corneal disease in cats. Surgery treatment is the recommended option. Acellular bioengineering cornea (ABC) is a popular and effective corneal transplantation material. However, no study has been published to evaluate the effectiveness and outcome of ABC lamellar transplantation for the treatment of feline corneal sequestrum (FCS). The purpose of this retrospective study was to evaluate the surgical effect of ABC lamellar transplantation in the treatment of FCS. All cats were diagnosed with FCS. All eyes received ABC lamellar transplantation for the first time, including 61 cats (62 eyes), aged 6–120 months. The average sequestrum size was 7.98 mm, with a medium of 7.75 mm (range, 4.75–11.75 mm), and the sequestrum thickness included 200 microns for 1 eye (1.61%), 300 microns for 28 eyes (45.16%), 400 microns for 29 eyes (46.77%), and 450 microns for 4 eyes (6.45%). All eyes retained vision after surgical treatment, and there was no recurrence during the follow-up period. This study has several limitations, including incomplete unification and standardization of data collection, some vacancies of follow-up time, inconsistency between then optical coherence tomography(OCT) examination and postoperative photo collection. Despite several limitations, our results show that ABC is easy to obtain and store, and has the choice of different sizes and thicknesses to achieve rapid corneal healing, and satisfactory visual and cosmetic effects in FCS treatment. Acellular bioengineering cornea can be a good alternative for the treatment of FCS.

Abstract

To retrospectively evaluate the effectiveness and outcome of lamellar keratoplasty using acellular bioengineering cornea (BioCorneaVet^TM) for the treatment of feline corneal sequestrum (FCS). The medical records of cats diagnosed with FCS that underwent lamellar keratoplasty with BioCorneaVet^TM between 2018 and 2021 with a minimum of 3 months of follow-up were reviewed. Follow-up examinations were performed weekly for 3 months, and then optical coherence tomography (OCT) examination was performed on select patients at 0, 3, 6, and 12 months post-operatively. A total of 61 cats (30 left eyes and 32 right eyes) were included. The Persian breed was overrepresented, 48/61 (78.69%). Four different thicknesses of acellular bioengineering cornea were used (200, 300, 400, or 450 microns), and the mean graft size was 8.23 mm (range, 5.00–12.00 mm). Minor complications were composed of partial dehiscence, and protrusion of the graft occurred in 7/62 eyes (11.29%). The median postoperative follow-up was 12.00 months (range, 3–41 months). A good visual outcome was achieved in 60/62 eyes (96.77%), and a mild to moderate corneal opacification occurred in 2/62 (3.23%). No recurrence of corneal sequestrum was observed. From the results, lamellar keratoplasty using acellular bioengineering cornea (BioCorneaVet^TM) is an effective treatment for FCS, providing a good tectonic support and natural collagen framework, and resulting in satisfactory visual and cosmetic effects.