Feline Corneal Sequestrum Research Articles

Surgical Management of Feline Corneal Sequestrum by Superficial Keratectomy and Autologous Platelet-Rich Fibrin Membrane Graft

Surgical Management of Feline Corneal Sequestrum by Superficial Keratectomy and Autologous Platelet-Rich Fibrin Membrane Graft

Optimising treatment approaches for feline corneal sequestra to improve long-term clinical outcomes.

Optimising treatment approaches for feline corneal sequestra to improve long-term clinical outcomes.

Long-term treatment outcomes and risk factors for recurrence in feline corneal sequestrum: 72 cases (2009-2017).

This study aimed to evaluate long-term treatment outcomes in feline corneal sequestrum (FCS), compare the recurrence rates between different surgical techniques, identify possible recurrence risk factors and monitor the development of FCS in the contralateral eye. The medical recordsof 72 cats (79 eyes) with FCS treated between 2009 and 2017 were retrospectively analysed. The most commonly affected breeds were Persian, domestic shorthaired and Burmesecats. The mean age was 6.9 years. Sixty-five cats (90%) were affected unilaterally. Sixty-six eyes (83%) underwent surgery: keratectomy in 34 eyes (52%) and keratectomy followed by a graft procedure in 32 eyes (48%). Recurrence occurred in 13 out of 66 eyes (19%) at a median of 245 days after surgery. Skull conformation, location of the FCS, type of surgical procedure and concurrent ocular surgery did not significantly affect the recurrence rate. Eighteen cats (27%) developed FCS in the contralateral eye at a median of 635 days after surgery. Limitations are related to the retrospective nature of the study, the use of telephone follow-up for assessment of recurrence in some cats and the small number of cases. Surgical excision had a successful outcome in most cases. The type of surgical procedure and skull conformation did not affect the recurrence rate. One-quarter of the cats developed FCS in the contralateral eye.

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

Simple SummaryCorneal 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.To retrospectively evaluate the effectiveness and outcome of lamellar keratoplasty using acellular bioengineering cornea (BioCorneaVetTM) for the treatment of feline corneal sequestrum (FCS). The medical records of cats diagnosed with FCS that underwent lamellar keratoplasty with BioCorneaVetTM 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 (BioCorneaVetTM) is an effective treatment for FCS, providing a good tectonic support and natural collagen framework, and resulting in satisfactory visual and cosmetic effects.

Use of SoftShield® collagen lenses in feline corneal sequestrum surgery

Feline corneal sequestrum develops secondary to the quantitative or qualitative deficit of the lacrimal tear film or represents a sequela in the healing process of corneal ulcers. The classic surgical approach is keratectomy and corneal-conjunctival flap for which not only special equipment is required (surgical microscope, cornea surgery kit), but also good knowledge of the technique of corneal sutures. For 32 cats diagnosed with corneal sequestrum (Persian, Exotic Shorthair, British Shorthair and Domestic Shorthair), a new surgical protocol was performed: keratectomy, application of the SoftShield® collagen contact lens and third eyelid flap. The sutures were maintained for three weeks. The healing of the cornea was achieved with minimal scarring, compared to the cases in which the corneal-conjunctival flap was performed. This surgical technique for feline corneal sequestrum can be performed by any veterinarian because it does not require special equipment or knowledge of corneal suture techniques.

Corneal sequestra in cats: 175 eyes from 172 cases (2000-2016).

To report the clinical outcomes of different surgical treatments used to manage feline corneal sequestra in a large number of cases. Medical records of 172 cats affected by feline corneal sequestra and surgically managed by different techniques were retrospectively evaluated. Signalment, surgical technique, visual outcomes, postoperative corneal clarity and recurrence were evaluated. One hundred and seventy-two cats (175 eyes) of different breeds, ages and sex were included in the retrospective case series. The Persian was the most represented breed (123/172; 71.5%), followed by Exotic Shorthair breed (21/172; 12.2%), Domestic shorthair breed (21/172; 12.2%) and a smaller group of other different breeds (7/172). Surgical management included a superficial (84/175 eyes) or deep (91/175 eyes) lamellar keratectomy in association with the following covering techniques (tectonic support and/or protective support): nictitans membrane flap (n=84), conjunctival pedicle graft (n=52), BioSISt graft (n=9), corneoconjunctival transposition (n=7), corneoconjunctival transposition+nictitans membrane flap (n=6), conjunctival free island graft (n=6), BioSISt+conjunctival pedicle graft (n=6), BioSISt+nictitans membrane flap (n=4) and bridge conjunctival graft (n=1). At the end of the retrospective case series, visus was present in all patients and no or mild corneal opacity was detected in 86% (151/175 eyes) of the patients. Sequestra recurred in 20 eyes (20/175; 11.4%) within 2 years. This paper describes the clinical outcomes of a large number of cases of feline corneal sequestra treated with varying surgical techniques and provides useful insight regarding the prognosis and outcomes of these techniques within feline ophthalmology.

Use of cyanoacrylate adhesive in the surgical management of feline corneal sequestrum: 16 cases (2011-2018).

To evaluate the use of cyanoacrylate adhesive as an adjunct to lamellar keratectomy in cats with corneal sequestrum. Medical records were reviewed to identify cats with naturally occurring midstromal corneal sequestra treated with lamellar keratectomy and cyanoacrylate adhesive. All cats also had a bandage contact lens placed for postoperative comfort. Data collected included breed, age, sex, and reproductive status of the cat, eye involved, presence or absence of neovascularization at the time of surgery, history of prior sequestra, additional ocular procedures performed, use of neuromuscular blocking agents, procedure time, time to cessation of topical medications, time to recurrence or last follow-up, and complications aside from recurrence. Sixteen cats met study criteria, with a median follow-up time of 17.5months in those without recurrence. Median time to cessation of topical medications was 4weeks. Fourteen cats (87%) have not experienced recurrence. Other than recurrence in two cats, no significant complications were noted. Aside from purebred status, no commonalities were found between the two cats with recurrence. Neuromuscular blocking agents were not used during surgery in most cases. Median procedure time was 10minutes. Cyanoacrylate adhesive is an effective and safe alternative to grafting procedures in cats undergoing lamellar keratectomy for treatment of corneal sequestrum. Recurrence rates are comparable to those seen with grafting techniques. Benefits of this approach include decreased anesthesia time, lower procedure costs, and short duration of postoperative treatment.

Use of biocompatible xenograft for the surgical treatment of feline corneal sequestrum after lamellar keratectomy

A Persian cat was referred to our clinic for evaluation of a black plaque located on the cornea of the right eye noticed by the owner three months prior to presentation. Reported clinical signs included ocular discomfort with blepharospasm and epiphora.The diagnosis of corneal sequestrum was made. Due to morphology, chronicity and severity of the symptoms, the cat was treated surgically with lamellar keratectomy followed by covering of the defect with a porcine small intestine derived xenograft. The excellent result was in accordance with the previously reported cases.

Surgical Outcome and Histopathological Findings of Feline Corneal Sequestrum

Corneal sequestration was diagnosed in the left eye of a 4-year-old neutered female cat. After obtaining appropriate history, slit lamp biomicroscopy, Schirmer's tear test and fluorescein dye test was performed.

Use of a porcine urinary bladder acellular matrix for corneal reconstruction in dogs and cats.

To describe the use of a porcine urinary bladder acellular matrix for surgical reconstruction of the cornea in cases of canine and feline deep corneal ulcers, and feline corneal sequestra. Twenty-seven dogs and three cats with deep corneal ulcers and seven cats with corneal sequestra were included in the study with overall 38 eyes. For each patient, the necrotic material (ie corneal sequestrum or collagenolytic tissue) was removed by circular lamellar keratectomy. The collagen graft was then cut and prepared to match the stromal defect and then sutured into the lamellar keratectomy bed using interrupted and continuous patterns of absorbable polyglactin 9-0 sutures. Postoperative medical treatment consisted of topical and systemic administration of antibiotics, combined with topical administration of atropine sulfate. The animals were examined 18, 45, and 90 days after the surgery. Postoperative examination revealed complete integration of the biomaterial in 93.5% of ulceration cases in both species and in 100% of feline corneal sequestrum cases. In two cases of ulceration (1 dog and 1 cat), progression of the collagenolytic process at the graft periphery required an additional conjunctival graft 7 days after the first surgery. At 90 days post-op, 100% of the eyes were sighted. Use of a porcine urinary bladder acellular matrix appears to be effective in the surgical management of deep corneal ulcers and feline corneal sequestra.

Corneal grafting for the treatment of feline corneal sequestrum: a retrospective study of 18 eyes (13 cats).

To determine the clinical outcome of corneal grafting for the treatment of feline corneal sequestrum (FCS). Domestic cats. A review of the medical records of cats that underwent keratoplasty as a treatment of FCS at the VTH-UAB, from 2002 to 2012, was carried out. Thirteen cats (18 eyes) of different breed, age, and gender were included. Persian cats were overrepresented (12/13;92%). There were nine males and four females, of a mean age of 3.4 years (0.7-7.1). Ipsilateral chronic corneal ulceration was reported as the most common concurrent ocular disease (6/18;33%). Keratoplasty was performed bilaterally in 5 cats (5/13;38%) and unilaterally in 8 (8/13;62%). Lamellar keratoplasty was performed in 17 eyes (17/18;95%) and full-thickness keratoplasty in 1 (1/18;5%). Mean graft size was 8.3 mm (4-11.5). Fresh homologous graft was performed in 2 eyes (2/18;11%) and frozen graft in 16 (16/18;89%). Of the latter group, homologous graft was performed in 6 eyes (6/16;37.5%) and heterologous in 10 (10/16;62.5%). In all the cats, postoperative treatment included topical antibiotics, corticosteroids, cycloplegics, and 0.2% cyclosporine A. Median follow-up time was 18.2 months, and main postoperative complications were diffuse mild epithelial pigment formation (2/18;11%), graft malacia (1/18;5%), and sequestrum recurrence (1/18;5%). Mean epithelial healing time was 19.2 days. Good visual outcome was achieved in all the eyes (100%), the majority of them having faint or mild corneal opacity (15/18;83%). Keratoplasty is an effective surgical treatment for FCS. The donor tissue provides excellent tectonic support to the affected corneas, with good visual and cosmetic outcome.

Porphyrins are not present in feline ocular tissues or corneal sequestra

To determine if feline lacrimal glands, glands of the third eyelid, corneas, and corneal sequestra contain porphyrins, which could be responsible for the brown/amber discoloration of corneal sequestra and tears in affected cats. Samples of grossly normal cornea, lacrimal gland, gland of the third eyelid, and sequestra obtained via keratectomy were collected. Porphyrin concentrations of the homogenate were determined by spectrofluorometry with protoporphyrin IX and coproporphyrin III dihydrochloride used as standards. A hamster harderian gland was used as a positive control. Normal tissues were harvested from one eye each of 14 nonclient owned, adult, mixed-breed, short-hair cats euthanized for reasons not associated with this study. Eighteen sequestra were acquired from cats undergoing unilateral lamellar keratectomies. Breeds of the affected cats included eight Himalayan, five domestic shorthair, and one each of four other breeds. Only the positive control and standards contained levels of porphyrins above background. All feline samples examined were histologically normal with no evidence of porphyrins. Porphyrins are absent in normal feline lacrimal glands, corneas, and corneal sequestra. Porphyrins do not appear to be the cause of the brown/amber color of feline corneal sequestra.

Amniotic membrane transplantation for the treatment of feline corneal sequestrum: pilot study

To describe and evaluate the use of equine amniotic membrane trans-plantation after lamellar keratectomy for the treatment of corneal sequestrum in cats. Six cats (seven eyes) of various breed and ages with corneal sequestra were treated surgically with lamellar keratectomy and amniotic membrane transplantation. All the sequestra and a small piece of the amniotic membranes used for each surgery were submitted for histopathologic examination. Five of the seven eyes showed minimal level of scarring in the cornea and good transparency. No recurrences of the sequestra have been noted during the follow-up period (3-9 months). One eye had necrosis of the amniotic membrane 2 weeks after the surgery. The sequestrum of this eye showed a high level of bacterial contamination on histopathology. Three months later the same cat developed a descemetocele in the area where the necrotic amniotic membrane was rejected. A second eye developed a perforation under the amniotic membrane two weeks after the surgery. The sequestrum of this eye was deep and without vascularization. Amniotic membrane transplantation after lamellar keratectomy was a valid procedure for surgical treatment of corneal sequestrum in cats. The procedure resulted in excellent cosmesis and functional vision in five of seven eyes; although case selection is important, particularly to exclude the very deep and non-vascularized sequestra.

Ultrastructural findings in feline corneal sequestra

(1) To describe the ultrastructural features of corneal sequestra in cats; and (2) to enhance our understanding regarding the pathogenesis of feline corneal sequestration. Nine corneal sequestra were harvested via keratectomy from globes of nine cats. The sequestra were routinely fixed then postfixed for high resolution light and transmission electron microscopy (HR-LM and TEM, respectively). The tissues were embedded in Epon/Araldite. Sections of 0.5-microm thickness were cut and stained with 1% toluidine blue in 1% sodium tetraborate solution for HR-LM. Ultrathin sections were collected on copper grids and stained with uranyl acetate and Sato's lead stain for TEM. Ultrathin sections were examined and the images were captured on an Advantage HR CCD camera using a Hitachi 7500 electron microscope operated at 80 kV. Two healthy corneas from two cats were harvested immediately following euthanasia. These corneal tissues (control samples) were processed in the same manner as the corneal sequestra for HR-LM and TEM. A portion of each sequestrum was also submitted for polymerase chain reaction (PCR) testing for infectious agents including feline herpesvirus-1 (FHV-1), Toxoplasma gondii, Chlamydophila felis and Mycoplasma spp. Ultrastructure of healthy corneal tissues revealed basal corneal epithelial cells aligned adjacent to a thin acellular layer similar to Bowman's layer with underlying tightly packed, regularly arranged, collagen fibrils oriented in different planes. Keratocytes were elongated and had long and irregularly shaped nuclei, and cytoplasm contained rough endoplasmic reticulum and abundant membrane-bound vesicles. In contrast, corneal sequestra contained varying amounts of an amorphous, electron-dense substance, continuous with intact basal epithelial basement membranes peripherally, and overlying corneal ulceration and loosely packed collagen fibrils. Remnants of necrotic keratocytes were seen in spaces between disarranged collagen layers. In all samples, occasional keratocytes exhibited morphology indicative of apoptosis including clumping and margination of chromatin, and shrunken cytoplasm. Varying degrees of inflammation were noted on HR-LM and TEM of affected corneas including peri- and intralesional neutrophils, lymphocytes, plasma cells, and macrophages. Corneal sequestra were FHV-1-positive (n = 3), FHV-1- and T. gondii-positive (n = 1), T. gondii-positive (n = 3), or negative for DNA of these infectious agents (n = 2) using PCR. All corneal sequestra were negative for DNA of Chlamydophila felis and Mycoplasma spp. using PCR. Apoptosis may play a role in the pathogenesis of feline corneal sequestration independent of the presence of DNA of these infectious organisms. Prospective clinical studies are warranted to further understand the significance of T. gondii in relation to feline corneal sequestration.

Qualitative tear film and conjunctival goblet cell assessment of cats with corneal sequestra

To evaluate the tear film qualitatively and conjunctival goblet cell numbers in cats with and without corneal sequestra. ANIMALS STUDIED AND PROCEDURES: This was a prospective evaluation of 11 cats with corneal sequestra and 14 control eyes that were either the contralateral normal eye when the sequestrum was unilateral or from control cats of similar age with no ocular disease. All cats in this study were examined by a veterinary ophthalmologist. The ophthalmic examinations included a neuro-ophthalmic evaluation, Schirmer tear tests, fluorescein staining, tear film break-up times, applanation tonometry, biomicroscopy, and indirect ophthalmoscopy. The palpebral conjunctiva at the dorsal nasal, ventral nasal, dorsal temporal and ventral temporal fornices were biopsied after topical anesthetic was applied to the cornea and conjunctiva. The conjunctival biopsies were fixed in formalin and sectioned routinely and stained with hematoxylin and eosin, and periodic acid-Schiff. These slides were examined by light microscopy by a blinded examiner. Goblet cell numbers were compared to conjunctival basal epithelial cell numbers by region. The goblet cell numbers by region from the eyes with sequestra was statistically compared to those from eyes without sequestra, with a student's paired t-test. Conjunctival swabs were collected from the cats with corneal sequestra and submitted for polymerase chain reaction for Herpes felis, Chlamydia psiitticia, and Mycoplasma felis. The corneal sequestra were removed by surgical keratectomy and fixed and stained routinely, and examined by light microscopy. No neurologic abnormalities were detected in any of the cats. The Schirmer tear tests (eyes with sequestra 14+/-5.1 mm/min; normal eyes 15+/-6.8 mm/min) and intraocular pressures (eyes with sequestra 21+/-6.6; normal eyes 22+/-5.8) were within normal reference ranges for cats. Biomicroscopic examinations revealed varied sizes and depths of brown- and amber-colored corneal sequestra. No abnormalities were noted on indirect ophthalmoscopic examinations. The tear film break-up time was 21 s (+/-12) for the normal eyes (n=14) and 14 s (+/-13) in eyes with corneal sequestra (n=11). The average goblet/epithelial cell ratios by region for the normal eyes and the eyes with sequestra respectively were 0.66, 0.56 for the dorsal nasal fornix, 0.68, 0.57 for the ventral nasal fornix, 0.63, 0.48 for the temporal dorsal fornix, and 0.55, 0.49 for the temporal ventral fornix. There were no significant differences in tear film break-up times and goblet cell numbers in eyes with corneal sequestra and those without sequestra. Three conjunctival swabs from two of 11 cats with sequestra were positive with PCR for Herpes felis virus. These included one cat with bilateral sequestra and one cat with unilateral corneal sequestrum. The pathogenesis of feline corneal sequestra does not appear to be linked primarily to abnormal goblet cell numbers, qualitative tear film abnormalities, and accelerated tear film break-up time.

Feline corneal sequestrum: laboratory analysis of ocular samples from 12 cats.

Feline corneal sequestrum is a common ocular condition typified by brown to black discoloration of the cornea. The nature of the discoloration has not been identified. The purpose of this study was to perform a laboratory investigation of ocular samples from 12 clinical cases of feline corneal sequestrum in an attempt to characterize the nature of the discoloration. The 12 cases were referred to the Ophthalmology Unit at the Animal Health Trust between April and September 2000, and were also part of a clinical review of 64 cases of feline corneal sequestrum described separately. Five laboratory techniques that are routinely performed at the Biomaterials Unit, Aston University were employed for analysis of the ocular samples. Ocular material included corneal sequestrum, tear samples, meibomian gland secretions, and bandage contact lenses from the 12 clinical cases. High-performance liquid chromatography data showed that total tear lipid in affected eyes was significantly lower than in control eyes (P = 0.016); total tear lipid in affected eyes was lower than in the unaffected, contralateral eyes of the same cat but the difference was not significant (P = 0.29). The presence of an unknown lipid class was observed in tears and meibomian secretions of affected, contralateral and control eyes. Scanning electron microscopy showed that the discoloration in affected corneas was not due to the presence of iron. Fluorescence spectroscopic analysis of sequestra, unaffected corneas and contact lenses (from affected and contralateral/unaffected eyes) showed that lipid and protein were present but did not play an important role in sequestra. Ultraviolet-visible light absorbance spectroscopy revealed a peak at 385 nm in unaffected corneas that was absent in sequestra and the difference was significant (P < 0.0001); this peak may be a characteristic feature of the normal feline cornea. The absorbance spectra displayed a peak at 280 nm in two sequestra suggesting that chromophore groups (e.g. melanin) were present. Optical microscopy performed on 10 sequestra revealed the presence of particles, which were consistent with the appearance of melanin particles, providing laboratory evidence that characterized the nature of the discoloration as melanin for the first time.

Feline corneal sequestra: a review of 64 cases (80 eyes) from 1993 to 2000.

Feline corneal sequestrum is a common condition of the feline cornea. The purpose of this study was to provide a detailed description of the clinical features of the condition including the response to different management options and to assess the rate of recurrence. The medical records of 64 cases (80 eyes) of feline corneal sequestra that presented to the Animal Health Trust from 1993 to 2000 were reviewed. Fifty-two cases were reviewed retrospectively; 12 cases were assessed prospectively between April and September 2000 as part of a separate study. The Persian was the most frequently encountered breed and the mean age of affected cats was 5.6 years. At initial presentation, sequestra were unilateral in 58 cats and bilateral in 6 cats, 5 of which were Persians. Ocular discomfort and ocular discharge were common presenting signs, occurring in 42 and 36 eyes, respectively. Seventy-four eyes were managed surgically with keratectomy only (n = 44) or keratectomy followed by a graft procedure (n = 30). Sequestra recurred in 16 eyes in the study. There was no significant difference in the rate of recurrence between eyes that received a graft procedure (n = 5) and eyes that did not (n = 11) (P = 0.56). Complications following transection of conjunctival pedicle grafts were observed. Brown to black discoloration of noncorneal tissue and therapeutic biomaterials was observed, including discoloration of both viable and apparently nonviable grafted conjunctival tissue, small intestinal submucosa graft material and bandage contact lenses.

Use of high-resolution ultrasound as a diagnostic tool in veterinary ophthalmology.

The recent development of a 20-MHz, high-frequency ultrasound probe has allowed tissue to be visualized at resolutions of 20 to 80 microm, which is similar to a low-power histologic view. This high degree of resolution, however, limits tissue penetration to 5 to 10 mm, which is ideal for examination of the anterior segment of the eye. The detail provided by high-resolution ultrasound readily permits the clinician to distinguish between various anterior segment entities that may appear similar but are treated quite differently, such as anterior uveal tumors, iridociliary cysts, and iris bombé. High-frequency ultrasound is also a valuable aid in creating a surgical plan for treatment of ocular disorders in which the cornea is opaque, such as feline corneal sequestrum and tumor invasion into the cornea. Other applications of this technology include elucidation of the pathogenesis of glaucoma in veterinary patients and evaluation of regions of the lens that are difficult to examine directly.

Lamellar keratoplasty for the treatment of feline corneal sequestrum.

A lamellar keratoplasty was used to treat corneal sequestrum in four Persian cats (six eyes). Following a superficial keratectomy, lamellar corneal allografts (feline corneal tissue) or heterografts (canine corneal tissue) which had been preserved at -20 degrees C were placed in the recipient cornea. All grafts became optically transparent within 2 months following surgery and no recurrences of the sequestrum have been noted during the follow-up period (4-30 months). We conclude that feline corneal sequestrum may be successfully treated with feline or canine donor corneal tissue using this technique.