Diamond burr debridement vs. grid keratotomy in canine SCCED with scanning electron microscopy diamond burr tip analysis.

OBJECTIVES: (i) Compare the outcome of canine SCCED treated with grid keratotomy (GK) or diamond burr debridement (DBD); (ii) Serially evaluate morphologic and elemental composition changes to diamond burr tips. ANIMALS STUDIED: A total of 91 eyes of 88 canine SCCED patients treated at the University of Missouri (2005-2015); 75 fresh cadaver porcine globes. PROCEDURES: (i) Medical records were reviewed retrospectively. Data were analyzed for age, sex, breed, procedure performed, eye(s) on which the procedure was performed, time to healing after a single surgical procedure, performance of a second surgical procedure, contact lens placement, and postprocedural complications. (ii) Three naïve 3.5-mm medium grit burr tips were analyzed using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). DBD was performed for 120 s on 8-mm porcine corneal stroma using the Algerbrush® . Manufacturer-recommended cleaning protocols were followed. SEM and EDS analyses were performed in triplicate after 10, 25, and 50 DBD, cleaning, and sterilization cycles. RESULTS: There was no statistically significant difference in healing between DBD and GK groups (P = 0.50). No diamond particle damage after 10, 25, or 50 DBDs was detected. SEM secondary electron imaging and backscatter electron imaging after repeated uses demonstrated a build-up of contamination composed of carbon, sulfur, and calcium on burr tips. CONCLUSIONS: Both DBD and GK are effective treatment options for canine SCCED. Although complications are rare after DBD, build-up of contaminants may be a contributing factor. Additional cleaning and sterilization protocols are being investigated.

Comparación de las características corneales en gallina y codorniz como modelos experimentales de cirugía refractiva / Comparison of the characteristics in hen and quail corneas as experimental models of refractive surgery

OBJETIVO: Analizar y comparar la histología, la morfología y las medidas biofísicas corneales de la gallina y la codorniz para determinar qué modelo experimental animal es el más adecuado para la realización de estudios de investigación en cirugía corneal. MATERIAL Y MÉTODOS: Se estudiaron las medidas biofísicas de la córnea (curvatura, espesor, refracción y longitud axial) de 20 animales (10 gallinas y 10 codornices). Después las córneas fueron procesadas para el estudio de histología clásica bajo la luz del microscopio. RESULTADOS: Los 2 grupos analizados poseen una córnea similar a la del humano con respecto al número de capas y con una evidente capa de Bowman. El espesor corneal, así como la longitud axial del ojo de la gallina, 225,3 ± 18,4 μm y 12,8 ± 0,25 mm, respectivamente, fueron significativamente mayores que los de la codorniz (p < 0,01 y p < 0,001). El radio de curvatura de la córnea central de la gallina también fue significativamente mayor que el de la codorniz (p < 0,001). El poder refractivo de las 2 especies fue similar. La proporción del espesor estromal con relación a la córnea en la gallina fue más similar al humano (82,6%) que de la codorniz (72,5%). La densidad de la población de queratocitos en la gallina, 8,57 ± 1,49/5.000 μm2, correspondió a cerca de la mitad del número de queratocitos encontrados en la córnea de la codorniz (p < 0,005). CONCLUSIONES: La córnea de gallina, por su tamaño, espesor del estroma y similitud de proporción en sus capas con la córnea humana, es más adecuada para la cirugía refractiva corneal que la de codorniz

AIM: To compare the histological, morphological and the biophysical measurements between hen and quail corneas, in order to determine which of them were better suited for use as an animal model for research into corneal refractive surgery. MATERIAL AND METHODS: A study was performed using the biophysical measurements of the cornea (curvature, thickness, refraction, and axial length) of 20 animals (10 hens and 10 quails). The corneas were then prepared for histological analysis under microscopy light. RESULTS: The analysis showed that both groups have the same number of corneal layers as the human cornea and with an evident Bowman's layer. The thickness of the hen cornea and axial length of the eye, 225.3 ± 18.4 μm and 12.8 ± 0.25 mm, respectively, were larger than that of the quail (P < .01 andP < .001, respectively). The radius of curvature for the hen central cornea, 3.65 ± 0.08 mm, was greater than that for the quail (P < .001), but the refractive power of each cornea was similar. The proportion of total corneal thickness of the hen stroma, 82.6%, was more similar to that of the human than was the quail stroma, 72.5%. Within the hen stroma, the density of keratocytes, 8.57 ± 1.49 per 5,000 μm2, was about half that in the quail stroma (P < .005). CONCLUSIONS: Because of the large size of the hen cornea, the stromal thickness and proportional similarity of the corneal layers with human cornea, the hen maybe better than the quail as an alternative species suitable for use in studies of corneal refractive surgery

Effect of onion extract on corneal haze suppression after air assisted lamellar keratectomy.

This study evaluated the effect of onion extract on corneal haze suppression after applying the air assisted lamellar keratectomy. The air assisted lamellar keratectomy was performed on 24 canine eyes. They were treated with an artificial tear (group C), prednisolone acetate (group P), onion extract (group O) and TGF-ß1 (group T) three times per day from 7 to 28 days after the surgery. Corneal haze occurred on the all eyes and was observed beginning 7 days after the surgery. The haze was significantly decreased in groups P and O from day 14 compared with the group C using the clinical (group P; P=0.021, group O; P=0.037) and objective evaluation method (group P; P=0.021, group O; P=0.039). In contrast, it was significantly increased in group T from day 14 compared with group C based on the clinical (P=0.002) and objective evaluation method (P<0.001). Subsequently, these eyes were enucleated after euthanasia, and immunohistochemistry with α-SMA antibodies was done. The total green intensity for α-SMA was significantly more expressed in group T and significantly less expressed in groups P and O than in group C. Onion extract could have potential as a therapeutic in preventing corneal haze development by suppressing the differentiation of fibroblasts into myofibroblasts.

Evaluation of 30- and 25-diopter intraocular lens implants in equine eyes after surgical extraction of the lens.

OBJECTIVE: To determine appropriate intraocular lens (IOL) implant strength to approximate emmetropia in horses. SAMPLE POPULATION: 16 enucleated globes and 4 adult horses. PROCEDURES: Lens diameter of 10 enucleated globes was measured. Results were used to determine the appropriate-sized IOL implant for insertion in 6 enucleated globes and 4 eyes of adult horses. Streak retinoscopy and ocular ultrasonography were performed before and after insertion of 30-diopter (D) IOL implants (enucleated globes) and insertion of 25-D IOL implants (adult horses). RESULTS: In enucleated globes, mean +/- SD lens diameter was 20.14 +/- 0.75 mm. Preoperative and postoperative refractive state of enucleated globes with 30-D IOL implants was -0.46 +/- 1.03 D and -2.47 +/- 1.03 D, respectively; preoperative and postoperative difference in refraction was 2.96 +/- 0.84 D. Preoperative anterior chamber (AC) depth, crystalline lens thickness (CLT), and axial globe length (AxL) were 712 +/- 0.82 mm, 11.32 +/- 0.81 mm, and 40.52 +/- 1.26 mm, respectively; postoperative AC depth was 10.76 +/- 1.16 mm. Mean ratio of preoperative to postoperative AC depth was 0.68. In eyes receiving 25-D IOL implants, preoperative and postoperative mean refractive error was 0.08 +/- 0.68 D and -3.94 +/- 1.88 D, respectively. Preoperative AC depth, CLT, and AxL were 6.36 +/- 0.22 mm, 10.92 +/- 1.92 mm, and 38.64 +/- 2.59 mm, respectively. Postoperative AC depth was 8.99 +/- 1.68 mm. Mean ratio of preoperative to postoperative AC depth was 0.73. CONCLUSIONS AND CLINICAL RELEVANCE: Insertion of 30-D (enucleated globes) and 25-D IOL implants (adult horses) resulted in overcorrection of refractive error.