Length of metacarpal and metatarsal bones in five Iranian sheep breeds and their associations with ungula measurements

Background This study aimed to measure the length of metacarpal and metatarsal bones in five Iranian sheep breeds and to correlate the length of the bones with ungula measurements. Thoracic and pelvic limbs of 2-year-old, previously untrimmed, pastured Afshari, Moghani, Kurdi, Makoui, and Lori–Bakhtiari ewes, (n = 20 ewes per breed) were collected after slaughter. The following lengths were recorded in the metacarpal and metatarsal bones: from the margo proximalis lateralis to the lateral (L1) and medial (D1) cartilago physialis; from the margo proximalis lateralis to the margo abaxialis of the lateral (L2) and medial (D2) caput; from the cartilago physialis lateralis to the margo abaxialis of the lateral caput (X1); from the cartilago physialis medialis to the margo distalis of the caput ridge (X2) and from the margo axialis of cartilago physialis to the margo axialis of the lateral caput (X3). Additionally, measurements of the ungula including pars dorsalis length, pars mobilis lateralis and medialis height, pars dorsalis height to the ground and to the solea cornea, thickness of the solea in the pars dorsalis, pars mobilis lateralis and medialis, solea cornea length and angulus dorsalis were recorded in the medial and lateral digits of the thoracic and pelvic limbs. Data on length of the metatarsal and metacarpal bones were analysed using mixed model equations while Pearson correlations were calculated between metacarpal and metatarsal bones and ungula measurements. Results Lori- Bakhtiari and Moghani ewes had greater L1, L2, and D1 and D2 while X1, X2 and X3 was greater in Kurdi ewes (P < 0.05). Measurements such as L1, L2, D1 and D2 were greater in the metatarsal than in metacarpal bones (P < 0.05) and the opposite was observed for X1, X2 and X3 (P < 0.05). No asymmetry was observed between the lateral and medial measurements (P > 0.05). Low to moderate correlations were observed between bone and ungula measurements (P < 0.05). Conclusion Under the conditions of this study, differences in metacarpal and metatarsal bone measurements were observed between breeds but no asymmetry was observed between lateral and medial bones. Results indicate an association between metacarpal and metatarsal bones ungula measurements. This could provide baseline information for the development and/or improvement of current ungula health protocols in the studied sheep breeds.

Characteristic of the central cornea thickness in healthy children and in patients with congenital glaucoma

Background. Ophthalmic hypertension is one of the most important diagnostic criteria for congenital glaucoma. The «gold standard» for measuring intraocular pressure (IOP) is the applanation tonometry (Maklakov and Goldmann methods). However, the thickness of the central corneal zone has a significant effect on the value of IOP measured by these methods. The aim of this study was to compare the central corneal thickness (CCT) in children with congenital glaucoma and in healthy children. Material and methods. We examined 15 children aged from 7 months to 14 years (22 eyes) with congenital glaucoma. In the healthy children group, 26 subjects from 7 to 17 years old (51 eyes) were examined. CCT was measured in all subjects using the optical coherence tomograph Carl Zeiss Cirrus HD-OCT 5000 with an external lens for cornea scanning. The examination was carried out in pachymetry mode; the average thickness of the central ring having a diameter of 2 mm was evaluated. Results. Central corneal thickness in children with glaucoma ranged from 471 to 771 microns, the average value was 561.5±72.26 microns. In the group of healthy children, CCT was in the range of 480-597 microns with an average value of 529.88±29.33 microns. Thus, we noted a higher average value of the central corneal thickness and its higher variability in children with glaucoma in comparison with the group of healthy children. Conclusion. All children with glaucoma and suspected glaucoma should routinely perform pachymetry prior to applanation tonometry. One should consider the central corneal thickness when assessing intraocular pressure. Key words: congenital glaucoma, pachymetry, optical coherence tomography, central corneal thickness, applanation tonometry, intraocular pressure.

Nomogram for Single-pass Two-speed Automated Microkeratome Graft Preparation for Ultrathin Descemet Stripping Automated Endothelial Keratoplasty

PurposeTo create a nomogram including the translational speed of the microkeratome blade, microkeratome head size and precut tissue thickness to predict the postcut thickness for Descemet stripping automated endothelial keratoplasty (DSAEK) to obtain the thinnest possible graft.MethodsThis prospective study incorporated 48 grafts for DSAEK from March 2017 to June 2020. Corneal tissue for DSAEK was prepared by 3 experienced physicians using the Moria Evolution 3E (Moria Inc, Antony, France) microkeratome with 400, 450 and 500 mm head sizes. Precut central corneal thickness was measured with a DGH 550 handheld pachymeter (Pachette 2), taking an average of 3 readings. The microkeratome head was selected according to precut tissue thickness. The target donor lamella thickness ranged from 70 to 120 μm, and the selected microkeratome head size was 150μm less than the donor cornea thickness. Two translational speeds were used for the microkeratome cuts. One month after surgery, the central lenticular thickness was measured with a Visante® Optical Coherence Tomography caliper (Carl Zeiss Meditec Inc, Germany). A descriptive analysis was performed.ResultsForty-eight donor grafts were prepared. Mean graft thickness was 97.58 ± 29.84 μm (range 39-176 μm). Of the 48 samples, central graft thickness was <120µm (81.3%) in 39, <100 µm (58.3%) in 28 and <80µm (37.5%) in 18 at 1-month follow-up. There were no statically significant differences between translational speeds. ConclusionsA nomogram with an automated microkeratome to obtain thin grafts for DSAEK provided good graft thickness results without donor waste.

Glaucoma in self-reported relatives and non-relatives of Igbo glaucoma patients in Enugu, Nigeria

Purpose: To compare proportion of glaucoma and the associated factors among self-reported relatives and non-relatives of predominantly Igbo glaucoma patients Methods: An analytical cross-sectional survey of participants attending a free eye screening dedicated to relatives of glaucoma relatives in Enugu, Nigeria was carried out in July 2017. Non-relatives of glaucoma patients were expected to present for the free screening hence they were allowed to participate to prevent false claims. All participants were interviewed and underwent ophthalmic examinations. Glaucoma diagnosis was based on the ISGEO classification criteria adapted for Nigeria. Participants were subsequently grouped as glaucoma relatives and general population. Results: Forty-two and 56 participants were included in the relatives and general population groups respectively. The proportion of glaucoma in the relatives and general population groups was 43% and 20% respectively. The odds of having glaucoma was three times higher in relatives of patients than in general population (OR= 3.07, 95% CI; 1.25 – 7.5 p=0.013). About 52% of first-degree relatives were diagnosed with glaucoma. In the relatives’ group, 100% of siblings, 40% of children and 0% of parents had glaucoma. Proportion increased with age. Relatives were significantly younger than their probands at diagnosis (16years, p= 0.000). Only 5.6% of the relatives’ group were previously aware of diagnosis. Intraocular pressure and central cornea thickness were similar in both relatives and general population groups. Conclusions: In this screened Igbo population, over one-third of the relatives’ group and about one fifth of general population had glaucoma. Relatives were diagnosed at an earlier age. These findings will aid the advocacy for routine glaucoma family screening services.

Induced Astigmatism and Concomitant High Myopia Correction with Femtosecond Laser-assisted Intrastromal MyoRing Implantation

Purpose. Analysis of the results of astigmatism correction after penetrating keratoplasty and concomitant high myopia using the MyoRing ring implantation, clinical case as an example. Material and methods. Patient G., 51 years old, underwent surgery to correct astigmatism and concomitant high myopia. MyoRing was implanted in the right eye within corneal transplant limits using femtosecond laser-assisted intrastromal MyoRing implantation. Before the surgery uncorrected visual acuity at the operated eye was 0.01; corrected visual acuity 0.06; spherical component of refraction was (–)6.0 D, cylindrical component was (–)8.0 D. Mean keratometry in the right eye was 43.96 D. Corneal hysteresis was 6.5 mm Hg, corneal resistance factor was 5.5 mm Hg, cornea thickness in center was 529 mkm. The patient was followed up for one year. Results. In 12 months after the surgery visual acuity of the right eye without correction was 0.7 and 0.8 with correction. Spherical component was (–)1.0 D, cylindrical component was (–)2.0 D. Mean keratometry in the right eye was 35.10 D. Corneal hysteresis was 7.2 mm Hg, corneal resistance factor was 6.3 mm Hg, cornea thickness in center was 533 mkm. The patient was satisfied with the result of operation. Conclusion. Femtosecond laser-assisted intrastromal MyoRing implantation for correction induced astigmatism after penetrating keratoplasty and concomitant high myopia is efficient, safe and provides strengthening of biomechanical properties of the cornea besides refractive and visual effect. Key words: postkeratoplastic astigmatism, high myopia, MyoRing, femtosecond laser

A Review on Cornea Imaging and Processing Techniques

Background: Measuring cornea thickness is an essential parameter for patients undergoing refractive Laser-Assisted in SItu Keratomileusis (LASIK) surgeries. Discussion: This paper describes about the various available imaging and non-imaging methods for identifying cornea thickness and explores the most optimal method for measuring it. Along with the thickness measurement, layer segmentation in the cornea is also an essential parameter for diagnosing and treating eye-related disease and problems. The evaluation supports surgical planning and estimation of the corneal health. After surgery, the thickness estimation and layer segmentation are also necessary for identifying the layer surface disorders. Conclusion: Hence the paper reviews the available image processing techniques for processing the corneal image for thickness measurement and layer segmentation.

Ocular Biometrics of Vietnamese Young Adults with Myopia

BACKGROUND: Myopia is most prevalent type of refraction error. In some Asian countries, the prevalence of myopia can be 80 – 90% in the population aged 17 – 18. AIM: To analyze the correlation between ocular biometric indices and refraction status in Vietnamese young myopes. METHODS: A prospective cross – section study was conducted in young myopes. Data on axial length, central cornea thickness, corneal topography & anterior chamber depth and spherical equivalent were collected. Independent Sample T Test and ANOVA test were used to compare between groups. The correlations between ocular biometry and myopic spherical equivalent refraction were examined by Pearson Correlation with the level of significance p < 0.05. RESULTS: Totally, 418 eyes from 209 patients were recruited. The average axial length, central cornea thickness, cornea refraction & anterior chamber depth were 25.68 ± 1.09 mm, 539.78 ± 32.665 µm, 43.16 ± 1.369 D, 3.30 ± 0.243 mm, respectively. The correlation between axial length and spherical equivalent refraction (SER) was high (r = - 0.742, p < 0.0001) while those between central cornea thickness and cornea refraction were negligible (r = - 0.107, p = 0.029; r = -0.123, p = 0.012; respectively). There was no correlation between anterior chamber depth and spherical equivalent refraction (r = 0.019, p = 0.697). CONCLUSION: Among ocular biometric indices, axial length was significantly correlated with spherical equivalent of young adult patients.

Features of Femtosecond Correction of High Myopia through Small Access

Aim. To modify the calculated parameters of the lenticle extraction refractive surgery through a small access (SMILE), evaluate its safety and clinical efficacy in correcting high myopia.Materials and methods. 34 patients (68 eyes) underwent surgery by a modified SMILE technology under local anesthesia. In all cases, the patients had a high degree of myopia, in 37 % in combination with astigmatism.Uncorrected visual acuity before surgery averaged 0.05 ± 0.11, best corrected visual acuity of 0.94 ± 0.1, the pre-operative spherical refraction component was –7.23 ± 0.75, the cylindrical component was –0.48 ± 0.59.During the operation, to obtain the maximum possible refraction result using the proposed method, the standard operation parameters were changed: the corneal flap thickness was reduced to 100 μm, the neural optical layer by 5 μm, the diameter of the optical zone depended on the residual cornea thickness, which should exceed 280–290 μm. Corneal access was increased by 15–20 degrees.Results. The next day after surgery, monocular uncorrected visual acuity in distance in 73 % of patients was 0.8 or higher, and in 41 % of cases it was equal to or exceeded 1.0. The spherical equivalent on the first day after surgery had a slight hypermetropic shift, which was completely leveled by the year of follow-up. During the surgical intervention and in the postoperative period, no complications were noted.Conclusion. Using the proposed algorithm for calculating the refractive effect of the operation SMILE with a high degree of myopia allows obtaining a high refractive effect and avoiding possible complications.

Repeated Corneal Cross-Linking with Progressive Keratoconus

The purpose is to study the efficacy and safety of repeated UV corneal crosslinking in patients with advanced keratoconus after transepithelial crosslinking performed previously. Patients and methods. A retrospective analysis of the treatment results of 52 patients (52 eyes) with progressive keratoconus stage I-II according to the Amsler — Krumeich classification, which from 2012 to 2014 were treated by transepithelial corneal crosslinking. Based on objective clinical studies, the effectiveness of the treatment and the course of the process were evaluated. In some patients with a progressive course of the process (12 eyes), after the transepithelial crosslinking, a procedure of repeated UV crosslinking of the cornea was performed according to a standard protocol. Results. After transepithelial cross-linking within 24 months in 12 eyes (44 %) progression of the disease was observed, manifested by an increase in the refractive power of the cornea by 0.95 ± 0.18 D, a decrease in the thickness of the cornea from 484 ± 156 to 446 ± 87 microns. Repeated cross-linking was performed and after 6 months and positive dynamics was observed in 10 cases (83.3 %), visual acuity reached the preoperative level, the refractive power of the cornea was 50.3 ± 0.84 D. Stabilization of the process was noted in all 12 eyes, a decrease in the average refractive index of the cornea by an average of 1.1 ± 1.25 D, corneal astigmatism — by 1.2 ± 0.31 D, the cornea thickness to 427 ± 38.7 mc.Conclusion. The use of modified crosslinking protocols, in particular transepithelial with iontophoresis, has a lower efficiency, showing stabilization in 56 % of cases, compared to the standard, which must be considered when choosing a clinical approach and selecting patients. Performing recrosslinking using a standard protocol showed high efficiency and safety of the procedure in 100 % of cases, however, this approach should be studied on a larger number of observations.