Identifying crossing collagen fibers in human corneal tissues using pSHG images.

Polarization sensitive second harmonic generation (pSHG) microscopy has been used previously to characterize the structure of collagen fibers in corneal samples. Due to the typical organization of the corneal stroma, the information that pSHG provides may be misleading in points where two different collagen fiber bundles orient along different direction crossings. Here, a simulation that illustrates the problem is presented, along with a novel method that is capable of identifying these crossing points. These results can be used to improve the evaluation of corneal collagen structure, and it has been applied to analyze pSHG data acquired from healthy and keratoconic human corneal samples.

A comparison between internal and surface temperature measurement techniques during phacoemulsification cataract surgery: thermocamera versus thermocouple.

PURPOSE: Corneal and scleral burns, one of the main complications that can occur during a cataract operation, are produced by overheating due to the use of the phacoemulsifier. The temperature of the anterior chamber of the eye can be measured both invasively using thermocouples and non-invasively, but only superficially, using a thermocamera. METHODS: To compare the measures obtained from both techniques an in vitro experimental analysis was conducted on pigs' eyes. During a simulated phacoemulsification cataract operation both the surface temperature with a thermocamera and the temperature inside the anterior chamber with a thermocouple were recorded. For each procedure, the maximum temperature values measured by each technique were compared. RESULTS: The results of this research show that the difference between the maximum values measured with the two techniques is on average 0.5 degrees C. CONCLUSIONS: It is possible to employ a thermocamera technique instead of a thermocouple technique to provide an indication of the temperature inside the anterior chamber.

Ocular surface temperature in patients with evaporative and aqueous-deficient dry eyes: a thermographic approach.

OBJECTIVE: In recent decades infrared thermography (IRT) has facilitated accurate quantitative measurements of the ocular surface temperature (OST), applying a non-invasive procedure. The objective of this work was to develop a procedure based on IRT, which allows characterizing of the cooling of the ocular surface of patients suffering from dry eye syndrome, and distinguishing among patients suffering from aqueous deficient dry eye (ADDE) and evaporative dry eyes (EDE). APPROACH: All patients examined (34 females and 4 males, 23-84 years) were divided into two groups according to their Schirmer I result (⩽ 7 mm for ADDE and > 7 mm for EDE), and the OST was recorded for 7 s at 30 Hz. For each acquisition, the temperatures of the central cornea (CC) as well as those of both temporal and nasal canthi were investigated. MAIN RESULTS: Findings showed that the maximum temperature variation (up to 0.75 ± 0.29 °C) was at the CC for both groups. Furthermore, patients suffering from EDE tended to have a higher initial OST than those with ADDE, explained by the greater quantity of the tear film, evenly distributed over the entire ocular surface, keeping the OST higher initially. Results also showed that EDE patients had an average cooling rate higher than those suffering from ADDE, confirming the excessive evaporation of the tear film. SIGNIFICANCE: Ocular thermography paves the way to become an effective tool for differentiating between the two different etiologies of dry eye syndrome.

Clear corneal incision of 2.75 mm for cataract surgery induces little change of astigmatism in eyes with low preoperative corneal cylinder.

PURPOSE: To assess the early astigmatic effect induced by 2.75 mm clear cornea incisions with different locations for cataract surgery. METHODS: A total of 146 eyes of different patients were studied prospectively. Cataract surgery was performed by three surgeons, two using a temporal approach and one using a superior approach. For both approaches, the site of the 2.75 mm incision was allowed to vary slightly according to the characteristics of the eye and orbit. Computerized videokeratography was used to measure corneal astigmatism before surgery and after 1, 4, and 12 weeks. Corneal astigmatism was recorded as cylinder and axis and it was then converted to 2 power vector. Model based prediction and comparisons were made for the most commonly used corneal incision sites: 12 (both eyes), 2 (left eye), and 8 (right eye) o'clock meridian. RESULTS: After 3 months the differences in corneal astigmatism (JCC 0 ) between the incisions performed at 12 and 2 o'clock were not statistically significant (-0.08, 95% CI: -0.19, -0.02); the differences in JCC 0 between incisions at 12 and 8 o'clock were -0.17 (95% CI: -0.30, -0.05; p<0.01). After 3 months the change in JCC 0 for the patients with 0.5 D with-the-rule preoperatively were -0.32 (95% CI: -0.44, 0.21; p<0.01) for incisions at 12; -0.24 (95% CI: -0.36, 0.13; p<0.01) for incisions at 2; and -0.15 (95% CI: -0.27, -0.03; p<0.05) for incisions at 8. After 3 months the changes of JCC 0 for the patients with -0.5 D against-the-rule pre-operatively were 0.10 (95% CI: 0.04, 0.23) for incision at 12; 0.18 (95% CI: 0.04, 0.32; p<0.05) for incisions at 2; and 0.27 (95% CI: 0.14, 0.40; p<0.01) for incisions at 8 o'clock. The oblique astigmatic vector (JCC 45 ) was very modest in this sample before surgery and underwent minimal and nonsignificant change after it. CONCLUSIONS: This study has shown that a 2.75 mm clear corneal incision causes a small change of corneal cylinder regardless of incision site.

Ophthalmological aspects in allogenic bone marrow transplantation: Sjögren-like syndrome in graft-versus-host disease.

PURPOSE: A major complication of allogenic bone marrow transplantation (BMT) is graft-versus-host disease (GVHD), characterized principally by involvement of the eyes, producing a Sjögren-like syndrome (SLS). This study assessed the predictive role of the eye involvement in the onset of GVHD. METHODS: Thirty-five patients transplanted for hematological malignancies were routinely examined for ocular manifestation of dry eye. Examination includes the Schirmer I test, break-up time, Lissamine Green staining, fluorescein test, lactoferrin test and impression cytology. A threshold was established for quantitative analysis of SLS. RESULTS: Fifteen of 35 patients (40%) developed SLS during long-term follow-up. Ten of these (77%) developed acute or chronic GVHD. CONCLUSIONS: The possible etiology of SLS includes three factors: total body irradiation, ocular toxicity of chemotherapy and GVHD. A correlation was found between poor-prognosis GVHD and the occurrence of SLS.

Inhibition of viral replication in vitro by antiviral-treated amniotic membrane. Possible use of amniotic membrane as drug-delivering tool.

PURPOSE: To investigate if amniotic membrane (AM) incubated with antivirals can inhibit viral growth in vitro. METHODS: AM samples were incubated with a solution of acyclovir or trifluridine. The treated AM was placed onto monolayers of Vero cells, a continuous cell line from monkey kidney, infected with herpes simplex virus. Viral growth was assessed in comparison to control infected cells by direct examination with an inverted microscope at low magnification for the presence and extension of the typical cytopathic effect, or by estimation of viral genomes. RESULTS: AM soaked in acyclovir or trifluridine inhibited significantly the development of herpes simplex virus in cell cultures, based on the viral growth compared with controls. Non-treated AM did not significantly affect viral replication. CONCLUSIONS: Our preliminary in vitro data show that antiviral-treated amniotic membrane can inhibit viral replication. Therefore, the possibility to combine the previously published anti-inflammatory properties of AM with the capability to absorb antivirals and sustain drug release could be taken into consideration.

Clear corneal incision of 2.75 mm for cataract surgery induces little change of astigmatism in eyes with low preoperative corneal cylinder.

PURPOSE: To assess the early astigmatic effect induced by 2.75 mm clear cornea incisions with different locations for cataract surgery. METHODS: A total of 146 eyes of different patients were studied prospectively. Cataract surgery was performed by three surgeons, two using a temporal approach and one using a superi-or approach. For both approaches, the site of the 2.75 mm incision was allowed to vary slightly according to the characteristics of the eye and orbit. Computerized videokeratography was used to measure corneal astigmatism before surgery and after 1, 4, and 12 weeks. Corneal astigmatism was recorded as cylinder and axis and it was then converted to 2 power vector. Model based prediction and comparisons were made for the most commonly used corneal incision sites: 12 (both eyes), 2 (left eye), and 8 (right eye) oclock meridian. RESULTS: After 3 months the differences in corneal astigmatism (JCC 0 ) between the incisions performed at 12 and 2 oclock were not statistically significant (-0.08, 95% CI: -0.19, -0.02); the differences in JCC 0 between incisions at 12 and 8 oclock were -0.17 (95% CI: -0.30, -0.05; p<0.01). After 3 months the change in JCC 0 for the patients with 0.5 D with-the-rule preoperatively were -0.32 (95% CI: -0.44, 0.21; p<0.01) for incisions at 12; -0.24 (95% CI: -0.36, 0.13; p<0.01) for incisions at 2; and -0.15 (95% CI: -0.27, -0.03; p<0.05) for incisions at 8. After 3 months the changes of JCC 0 for the patients with -0.5 D against-the-rule pre-operatively were 0.10 (95% CI: 0.04, 0.23) for incision at 12; 0.18 (95% CI: 0.04, 0.32; p<0.05) for incisions at 2; and 0.27 (95% CI: 0.14, 0.40; p<0.01) for incisions at 8 oclock. The oblique astigmatic vector (JCC 45 ) was very modest in this sample before surgery and underwent minimal and nonsignificant change after it. CONCLUSIONS: This study has shown that a 2.75 mm clear corneal incision causes a small change of corneal cylinder regardless of incision site.

The influence of early diabetes on the pattern electroretinogram.

Pattern electroretinogram response and contrast sensitivity were evaluated in two groups of diabetic patients by means of psychophysical and electrophysiological methods. The first group consisted of subjects suffering from diabetic retinopathy in various stages of evolution; the second was composed of diabetic patients with no fundus alterations and with good visual acuity. In both groups of patients, when the pattern electroretinogram was altered, contrast sensitivity was also abnormal.

Congenital nystagmus: fine structure of human extraocular muscles.

The ultrastructure of the extraocular muscles of patients affected by congenital nystagmus is still to be defined. Specimens obtained from patients suffering from either oculomotor congenital nystagmus or nystagmus associated with strabismus were studied and compared with specimens obtained from patients enucleated for various pathologies but not affected by any oculomotor system disorder. The scleral myotendinous junction and the muscle body (venter) were examined. In both these areas, damaged muscle fibers were found. 'Mitochondrial cores' and concentric myofibrils characterized the extraocular muscles of the patients with oculomotor congenital nystagmus. In the extraocular muscles of the patients affected by nystagmus associated with strabismus we also found mitochondria with concentric cristae surrounding a highly electron-dense spherical body and numerous, large rods. In conclusion, these data indicate that both contractile and mitochondrial modifications might be signs of an altered muscle function and seem to indicate that oculomotor congenital nystagmus should be included among the list of oculomotor myopathies.

Extraocular muscles in congenital strabismus: muscle fiber and nerve ending ultrastructure according to different regions.

The ultrastructure of the extraocular muscles of patients affected by congenital strabismus is not completely known, and the structures responsible of the pathogenesis of this condition are still to be determined. Specimens obtained from patients suffering from congenital strabismus were studied and compared with specimens obtained from patients enucleated for various pathologies and not affected by any disorder in the oculomotor system. The scleral myotendinous junction, where the occurrence of an altered proprioceptive innervation was already reported, was examined, and findings obtained were compared with those observed in the muscle body (venter), where motor innervation is prominent and usually described as normal. Only a small number of damaged muscle fibers was found everywhere. The damage consisted in alterations of both contractile structures and mitochondria and resulted in severer lesions in the scleral myotendinous junction rather than in the muscle body. The normal muscle fibers were innervated by motor nerve endings with normal features and by few altered proprioceptors. The less damaged muscle fibers were innervated by normal motor nerve endings and severely damaged proprioceptors. The most severely damaged muscle fibers did not receive any type of innervation. These data seem to imply that the most important functional alteration in strabismus regards the scleral myotendinous junction. It is the authors' opinion that these findings might have a clinical importance in choosing the treatment to be pursued in patients with a squint.

Transthyretin-related TTR hereditary amyloidosis of the vitreous body. Clinical and molecular characterization in two Italian families.

Two unrelated Italian families affected by hereditary amyloidosis are described. Molecular genetic characterization demonstrated different mutations of the transthyretin gene. In all patients belonging to the TTR Ala 49 family the vitreous body, the heart and the peripheral nervous system were massively infiltrated by amyloid matter. In the TTR Pro 36 family vitreous opacities were the long-standing isolated manifestations of the disease. Two different patterns of vitreous deposits can be observed in these two families. The authors' data support the hypothesis that different pathological transthyretin proteins may have different affinity for the connective tissue in the vitreous.

Congenital hypertrophy of the retinal pigment epithelium in familial adenomatous polyposis. Novel criteria of assessment and correlations with constitutional adenomatous polyposis coli gene mutations.

BACKGROUND: Congenital hypertrophy of the retinal pigment epithelium (CHRPE) is the most common extracolonic manifestation of familial adenomatous polyposis (FAP) and is an early clinical marker of the disease. It seems to be correlated with the position of constitutional mutations of the adenomatous polyposis coli (APC) gene. METHODS: The authors investigated the expression of CHRPE and its correlation with the position of the APC gene in FAP patients and in "at risk" relatives from 31 FAP kindreds. To obtain comparable data on CHRPE expression, the authors developed a novel scoring system based on morphologic and dimensional criteria. RESULTS: A positive CHRPE score was obtained in 29 of 39 FAP patients (74%) and in 16 of 53 relatives who showed no clinical evidence of FAP (30%). Colonoscopy revealed polyps in 20 of the 47 relatives who could be examined. The cumulative sensitivity and specificity of CHRPE were 72.88% and 96.29%, respectively. APC gene mutations were characterized in 34 subjects from 17 kindreds. In 28 of the subjects, mutations were detected in exon 15, between codons 876 and 1324. Mutations were found in exon 9 in 6 subjects. In 3 of the 6 subjects, they were found at the site where both forms of alternative splicing of the exon occur (codon 437). In the other 3 subjects (another kindred), mutations were found in the portion of exon 9 in which alternative splicing occurs (codon 367). Only 1 of the 6 subjects (16.6%) with mutations in exon 9 had a positive CHRPE score, compared with 28 of 28 subjects (100%) with mutations in exon 15. None of the 3 subjects with mutations in codon 437 had a positive CHRPE score. The CHRPE scores of exon 15 mutation carriers varied markedly both within and among kindreds, irrespective of the mutation site. CONCLUSIONS: The results of this study indicate that the site of APC gene mutation influences CHRPE expression but is not the only factor responsible for the presence and level of retinal lesions in FAP patients.