Daniel Costa

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

OBJECTIVE To determine the clinical outcome of corneal grafting for the treatment of feline corneal sequestrum (FCS). ANIMAL STUDIED Domestic cats. PROCEDURES 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. RESULTS 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%). CONCLUSIONS 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.

Alfaxalone versus propofol in dogs: a randomised trial to assess effects on peri-induction tear production, intraocular pressure and globe position.

The purpose of this randomised trial was to compare the effects of alfaxalone and propofol on tear production (STT-1), intraocular pressure (IOP) and globe position (GP) in healthy dogs. Fourteen Beagles were randomly divided into two groups; dogs in one group received alfaxalone (3 mg/kg) (n=7) and dogs in the other group received propofol (6 mg/kg) (n=7), both administered intravenously. IOP and GP were evaluated at basal time (Tb) and T2,5,10,15,20,25&30 (minutes after complete drug administration). STT-1 was evaluated at Tb and T10,20&30. STT-1 and IOP results were analysed using analysis of variance and GP was analysed using the likelihood ratio χ2 test. Dogs in the alfaxalone group showed a significant reduction in STT-1 at T10&20 (P<0.05), while the propofol group did not show statistically significant differences in this parameter over time. Both anaesthetic drugs produced a transient elevation of IOP at T2 (P>0.05), which then decreased (P<0.01). While alfaxalone caused a ventral globe deviation that lasted from T2 to T10 (P<0.05) and was fully recovered at T30, propofol induced a ventral globe deviation from T2 to T5 (P<0.05), being restored at T20. These results suggest that both alfaxalone and propofol can be safely used for intraocular surgery, as they significantly reduce IOP. Furthermore, anaesthetic induction with propofol would be especially recommended for dogs with tear deficiencies.

A comparative study of corneal sensitivity in birds of prey

OBJECTIVE To determine and compare the corneal sensitivity in healthy wild diurnal and nocturnal birds of prey (BP) indigenous to Catalonia (Spain), and to establish if age is a determining factor in corneal sensitivity in those species. METHODS Ophthalmic examination was performed in 105 BP. Only birds with no ocular abnormalities were included in the study (n = 81): 21 diurnal BP (Falco tinnunculus: 16 fledglings, 5 adults) and 60 nocturnal BP (20 Athene noctua [9 fledglings, 11 adults], 20 Strix aluco [15 fledglings, 5 adults], and 20 Otus scops [6 fledglings and 14 adults]). Corneal touch threshold (CTT) was determined for each eye in five different corneal regions. Five attempts to cause a blink reflex were made in each region, and when three or more reflexes were positive, the pressure was deemed the CTT. Statistical analysis was performed using a Students t-test for independent data or an anova model. The results between species and age groups were compared using the Generalized Estimated Equations model. RESULTS There were no significant differences between any of the corneal regions (P = 0.25), or between the right (CTT = 4.9 ± 1.7 cm) and left (CTT = 4.8 ± 1.7 cm) eye in any of the species (P = 0.692). No difference was found between diurnal and nocturnal species (P = 0.913). Considering all the species, a significant difference was found between the mean CTT of fledglings (5.4 ± 1.2 cm) and adults (4.1 ± 2 cm), P < 0.001. A significant difference was found between fledglings and adults of A. noctua (P < 0.001) and S. aluco (P = 0.002). CONCLUSIONS There is no significant difference in CTT between the different corneal regions in all the species studied. Corneal sensitivity is similar between diurnal and nocturnal birds of prey. Age is a determining factor in the CTT of A. noctua and S. aluco, with fledglings having a significantly higher CTT.

Corneal grafting for the treatment of full‐thickness corneal defects in dogs: a review of 50 cases

OBJECTIVE To describe corneal grafting for the treatment of full-thickness corneal defects in dogs and to determine its effectiveness in preserving vision. METHODS A review of the medical records of dogs that underwent corneal grafting following corneal perforations (≥3 mm) at the VTH-UAB from 2002 to 2012 was carried out. RESULTS Fifty dogs of different breed, age and gender were included. Brachycephalic breeds were overrepresented (37/50;74%). All cases were unilateral, with euryblepharon being the most common concurrent ocular abnormality (20/50;40%). Full-thickness penetrating keratoplasties (FTPK) were performed in 21/50 eyes (42%) and lamellar keratoplasties (LK) in 29/50 eyes (58%). Frozen grafts (FroG) were used in 43/50 eyes (86%) and fresh homologous grafts (FreHoG) in 7/50 (14%). Of the former group, 26 were homologous (FroHoG:60%) and 17 heterologous (FroHeG:40%). A combination of topical medication (antibiotics, corticosteroids, cycloplegics, and 0.2% cyclosporine A) and systemic mycophenolate mofetil was administered. Median follow-up time was 200 days. Postsurgical complications included wound dehiscence (6/50;12%) and glaucoma (4/50;8%). Clinical signs of graft rejection were diagnosed as follows: FroHoG (13/26;50%), FroHeG (11/17;65%), FreHoG (4/7;57%), FTPK (12/21;57%), and LK (16/29;55%). Medical treatment successfully controlled graft rejection in 11/28 eyes (39%). Good anatomical outcome was achieved in 86% (43/50), of which 95% (41/43) were visual at last examination, with moderate opacification to complete transparency of the graft present in 48.2%. CONCLUSIONS Corneal grafting is an effective surgical treatment for full-thickness corneal defects in dogs. If graft rejection is present, additional medical or surgical therapy may be necessary, achieving a highly satisfactory visual outcome.

Cryopreservation (-20 °C) of feline corneoscleral tissue: histologic, microbiologic, and ultrastructural study.

OBJECTIVE To evaluate microbiological, histologic, and ultrastructural characteristics of short-term cryopreserved (STC) feline corneoscleral tissue (<1 year) and to compare it with long-term cryopreserved (LTC) tissue (>7 years). ANIMALS STUDIED Twenty healthy feline globes were obtained from 2003 to 2013. PROCEDURE After a decontamination protocol, globes were enucleated and stored at -20 °C in broad-spectrum antibiotics. Corneoscleral tissue was evaluated at different storage periods: <1 year (10 eyes) and >7 years (8 eyes). Two eyes were used as controls. Microbiologic study included direct (blood, McConkey, and Sabouraud agars) and enrichment (brain-heart infusion broth) cultures. Cryopreservation artifacts were evaluated by hematoxylin-eosin. Corneoscleral collagen organization and number of normal and dead keratocytes were established by transmission electron microscopy. RESULTS Although microbiologic cultures were positive only in STC [direct (20.8%); enrichment (37.5%)], significant differences between periods were only found in enrichment cultures (P = 0.006). Cryopreservation artifacts were most commonly observed in LTC tissues (P < 0.001). Normal keratocytes were predominant in STC corneas (STC 58.3%, LTC 12.5%) and apoptotic ones in LTC (STC 41.7%, LTC 75%), whereas necrotic keratocytes were only seen in LTC (LTC 12.5%) (P = 0.046). No structural differences were detected in collagen organization between STC and LTC (Pcornea = 0.147; Psclera = 0.362). CONCLUSIONS Cryopreservation of feline corneoscleral tissue seems to reduce bacterial contamination over time. Apoptosis is the main cause of death of cryopreserved feline keratocytes. Based on the lack of significant structural differences between STC and LTC samples, these cryopreserved tissues could potentially be used for tectonic support for at least 10 years without structural or microbiological impediment.

Effect of topical 1% cyclopentolate hydrochloride on tear production, pupil size, and intraocular pressure in healthy Beagles.

OBJECTIVE The objective of the study was to evaluate the effect of topical 1% cyclopentolate hydrochloride (CH) on tear production (TP), pupil size (PS), and intraocular pressure (IOP) in dogs. ANIMAL STUDIED Fifteen healthy beagle dogs from the UAB research-teaching colony. PROCEDURE Dogs without ocular diseases were included. Each animal received one drop of 1% CH ophthalmic solution in a randomly selected eye. TP, PS, and IOP were evaluated by means of STT-1, static pupillometry, and rebound tonometry, respectively. Evaluations were performed before drug instillation and at 0.5, 1, 2, 4, 8, 12, 24, 30, 36, 48, 54, 60, 72, 84, and 96 h postinstillation. Examinations took place in a room with fixed light intensity (40-55 lux). Statistical analysis was performed by means of generalized estimating equations for the effect on STT-1, pupil size, and IOP over time. RESULTS After unilateral application of 1% CH, significant pupillary dilation started at 30 min, reached its maximum at 12 h, and returned to pre-instillation size after 72 h. No significant effects were found on TP or IOP, at any time. No effects were observed in the untreated eye on any of the parameters evaluated. CONCLUSION Cyclopentolate hydrochloride could be considered a therapeutic alternative when use of a cycloplegic drug is needed and effects on tear production and IOP are unwanted.

Evaluation of corneal anaesthesia after the application of topical 2 per cent lidocaine, 0.5 per cent bupivacaine and 1 per cent ropivacaine in dogs

The objective of this study was to describe and compare the efficacy and duration of topical anaesthesia induced by 2 per cent lidocaine (L), 0.5 per cent bupivacaine (B) and 1 per cent ropivacaine (R) in the dog using 24 clinically healthy beagles with normal ocular examination. Dogs were randomly divided into three groups: 2 per cent lidocaine (n=8), 0.5 per cent bupivacaine (n=8) and 1 per cent ropivacaine (n=8). The baseline corneal touch threshold (CTT) was measured using a Cochet-Bonnet aesthesiometer. Following baseline CTT measurement, a single drop of the assigned anaesthetic was applied to each eye and the CTT was measured bilaterally within one minute after administration and every five minutes until the basal CTT value was restored. Data were analysed with non-parametric analysis of variance models and Dunnets test for post hoc analysis. One per cent ropivacaine was the most effective drug (LCTTmax=3 cm, BCTTmax=2 cm, RCTTmax=0 cm; P<0.001), and had the shortest latency (LLatency=5 minutes, BLatency=5 minutes, RLatency=1 minute; P<0.001) and the smallest AUC (LAUC=80 cm×minute, BAUC=68.25 cm×minute, RAUC=36.88 cm×minute; P<0.001). There was no statistical difference in the duration of corneal anaesthesia between the groups (P=0.09) and all topical anaesthetics tested reduced corneal sensitivity, although 1 per cent ropivacaine had the maximal and quickest anaesthetic effect. This drug could be used for specific diagnostic procedures where quick and short, but effective, corneal anaesthesia is needed.

Corneal thickness, endothelial cell density, and morphological and morphometric features of corneal endothelial cells in goats

OBJECTIVE To determine corneal thickness (CT), endothelial cell density (ECD), and morphological and morphometric features of caprine eyes and to assess effects of aging on these variables. SAMPLE 27 healthy eyes of 19 Murciano-Granadina goats. PROCEDURES Goats were classified into 2 age groups (kids, 14 months old [14 eyes]; and adults, 7 to 10 years old [13 eyes]). The ECD and CT were calculated in the central cornea and 4 peripheral quadrants. Mean cell area (MCA), pleomorphism (percentage of hexagonal cells), and polymegathism were evaluated in the central cornea. RESULTS Median values for kids were determined for ECD (3,831 cells/mm2; inter-quartile [25th to 75th percentile] range [IQR], 3,669 to 4,011 cells/mm2), CT (608 μm; IQR, 573 to 655 μm), MCA (255 μm2; IQR, 243 to 272 μm2), pleomorphism (80.53%; IQR, 78.83% to 83.30%), and polymegathism (19; IQR, 18 to 22). Median values for adults were determined for ECD (2,101 cells/mm2; IQR, 1,966 to 2,251 cells/mm2), CT (706 μm; IQR, 670 to 730 μm), MCA (466 μm2; IQR, 425 to 507 μm2), pleomorphism (67.80%; IQR, 65.50% to 70.00%), and polymegathism (21; IQR, 15 to 26). Values differed significantly between the 2 groups for all variables, except polymegathism. For both groups, the dorsal and temporal quadrants were the thickest and thinnest, respectively. Ventral ECD was the lowest for both groups. CONCLUSIONS AND CLINICAL RELEVANCE ECD decreased with age, whereas MCA, pleomorphism, and CT increased. Moreover, differences among regions of the cornea indicated that the central cornea should not be considered as representative of the entire cornea.