Ultrasonographic features of PMEL17 ( Silver ) mutant gene-associated multiple congenital ocular anomalies (MCOA) in Comtois and Rocky Mountain horses

OBJECTIVE: (1) To describe the ultrasonographic appearance of multiple congenital ocular anomalies (MCOA) in the eyes of horses with the PMEL17 (Silver) mutant gene. (2) To compare the accuracy of B-mode ocular ultrasound to conventional direct ophthalmoscopy. ANIMALS STUDIED: Sixty-seven Comtois and 18 Rocky Mountain horses were included in the study. PROCEDURES: Horses were classified as being carriers or noncarriers of the PMEL17 mutant allele based on coat color or genetic testing. Direct ophthalmoscopy followed by standardized ultrasonographic examination was performed in all horses. RESULTS: Seventy-five of 85 horses (88.24%) carried at least one copy of the Silver mutant allele. Cornea globosa, severe iridal hypoplasia, uveal cysts, cataracts, and retinal detachment could be appreciated with ultrasound. Carrier horses had statistically significantly increased anterior chamber depth and decreased thickness of anterior uvea compared with noncarriers (P < 0.05). Uveal cysts had a wide range of location and ultrasonographic appearances. In 51/73 (69.86%) carrier horses, ultrasound detected ciliary cysts that were missed with direct ophthalmoscopy. CONCLUSIONS: In this study, ultrasonography was useful to identify uveal cysts in PMEL17 mutant carriers and to assess anterior chamber depth.

Do optic nerve head and visual field parameters in patients with obstructive sleep apnea syndrome differ from those in control individuals?

BACKGROUND It has been suggested that sleep apnea syndrome may play a role in normal-tension glaucoma contributing to optic nerve damage. The purpose of this study was to evaluate if optic nerve and visual field parameters in individuals with sleep apnea syndrome differ from those in controls. PATIENTS AND METHODS From the records of the sleep laboratory at the University Hospital in Bern, Switzerland, we recruited consecutive patients with severe sleep apnea syndrome proven by polysomnography, apnea-hypopnea index >20, as well as no sleep apnea controls with apnea-hypopnea index <10. Participants had to be unknown to the ophtalmology department and had to have no recent eye examination in the medical history. All participants underwent a comprehensive eye examination, scanning laser polarimetry (GDx VCC, Carl Zeiss Meditec, Dublin, California), scanning laser ophthalmoscopy (Heidelberg Retina Tomograph II, HRT II), and automated perimetry (Octopus 101 Programm G2, Haag-Streit Diagnostics, Koeniz, Switzerland). Mean values of the parameters of the two groups were compared by t-test. RESULTS The sleep apnea group consisted of 69 eyes of 35 patients; age 52.7 ± 9.7 years, apnea-hypopnea index 46.1 ± 24.8. As controls served 38 eyes of 19 patients; age 45.8 ± 11.2 years, apnea-hypopnea index 4.8 ± 1.9. A difference was found in mean intraocular pressure, although in a fully overlapping range, sleep apnea group: 15.2 ± 3.1, range 8-22 mmHg, controls: 13.6 ± 2.3, range 9-18 mmHg; p<0.01. None of the extended visual field, optic nerve head (HRT) and retinal nerve fiber layer (GDx VCC) parameters showed a significant difference between the groups. CONCLUSION Visual field, optic nerve head, and retinal nerve fiber layer parameters in patients with sleep apnea did not differ from those in the control group. Our results do not support a pathogenic relationship between sleep apnea syndrome and glaucoma.

Real-time ultra-high optical coherence tomography monitoring of optical tissue effects caused by selective retina therapy

Purpose: Selective retina therapy (SRT) has shown great promise compared to conventional retinal laser photocoagulation as it avoids collateral damage and selectively targets the retinal pigment epithelium (RPE). Its use, however, is challenging in terms of therapy monitoring and dosage because an immediate tissue reaction is not biomicroscopically discernibel. To overcome these limitations, real-time optical coherence tomography (OCT) might be useful to monitor retinal tissue during laser application. We have thus evaluated a proprietary OCT system for its capability of mapping optical changes introduced by SRT in retinal tissue. Methods: Freshly enucleated porcine eyes, covered in DMEM upon collection were utilized and a total of 175 scans from ex-vivo porcine eyes were analyzed. The porcine eyes were used as an ex-vivo model and results compared to two time-resolved OCT scans, recorded from a patient undergoing SRT treatment (SRT Vario, Medical Laser Center Lübeck). In addition to OCT, fluorescin angiography and fundus photography were performed on the patient and OCT scans were subsequently investigated for optical tissue changes linked to laser application. Results: Biomicroscopically invisible SRT lesions were detectable in OCT by changes in the RPE / Bruch's complex both in vivo and the porcine ex-vivo model. Laser application produced clearly visible optical effects such as hyperreflectivity and tissue distortion in the treated retina. Tissue effects were even discernible in time-resolved OCT imaging when no hyper-reflectivity persisted after treatment. Data from ex-vivo porcine eyes showed similar to identical optical changes while effects visible in OCT appeared to correlate with applied pulse energy, leading to an additional reflective layer when lesions became visible in indirect ophthalmoscopy. Conclusions: Our results support the hypothesis that real-time high-resolution OCT may be a promising modality to obtain additional information about the extent of tissue damage caused by SRT treatment. Data shows that our exvivo porcine model adequately reproduces the effects occurring in-vivo, and thus can be used to further investigate this promising imaging technique.

Fluorescence lifetime imaging in retinal artery occlusion.

PURPOSE Fluorescence lifetime imaging ophthalmoscopy is a technique to measure decay times of endogenous retinal fluorophores. The purpose of this study was to investigate fluorescence lifetimes in eyes with central and branch retinal artery occlusion. METHODS Twenty-four patients with central or branch retinal artery occlusion were included in this study. The contralateral unaffected fellow eye was used as control. Measurements were performed using a fluorescence lifetime imaging ophthalmoscope based on a HRA Spectralis system. Fluorescence excitation wavelength was 473 nm, and mean lifetimes were measured in a short (498-560 nm) and in a long (560-720 nm) spectral channel. Fluorescence lifetimes in the area of retinal artery occlusion were measured and compared to corresponding areas in contralateral unaffected eyes. Additionally, findings were correlated to optical coherence tomography measurements. RESULTS Retinal lifetime images of 24 patients with retinal artery occlusion were analyzed. Mean retinal fluorescence lifetimes were prolonged by 50% in the short and 20% in the long spectral channel in ischemic retinal areas up to 3 days after retinal artery occlusion compared to the contralateral unaffected eyes. In the postacute disease stage there was no difference between the lifetimes of affected areas and unaffected fellow eyes. CONCLUSIONS Retinal artery occlusion leads to significantly longer fluorescence lifetimes of the retina in the acute phase and may serve as a useful indicator for acute ischemic retinal damage.

Fluorescence Lifetime Imaging in Stargardt Disease: Potential Marker for Disease Progression.

PURPOSE The purpose of this study was to describe autofluorescence lifetime characteristics in Stargardt disease (STGD) using fluorescence lifetime imaging ophthalmoscopy (FLIO) and to investigate potential prognostic markers for disease activity and progression. METHODS Fluorescence lifetime data of 16 patients with STGD (mean age, 40 years; range, 22-56 years) and 15 age-matched controls were acquired using a fluorescence lifetime imaging ophthalmoscope based on a Heidelberg Engineering Spectralis system. Autofluorescence was excited with a 473-nm laser, and decay times were measured in a short (498-560 nm) and long (560-720 nm) spectral channel. Clinical features, autofluorescence lifetimes and intensity, and corresponding optical coherence tomography images were analyzed. One-year follow-up examination was performed in eight STGD patients. Acquired data were correlated with in vitro measured decay times of all-trans retinal and N-retinylidene-N-retinylethanolamine. RESULTS Patients with STGD displayed characteristic autofluorescence lifetimes within yellow flecks (446 ps) compared with 297 ps in unaffected areas. In 15% of the STGD eyes, some flecks showed very short fluorescence lifetimes (242 ps). Atrophic areas were characterized by long lifetimes (474 ps), with some remaining areas of normal to short lifetimes (322 ps) toward the macular center. CONCLUSIONS Patients with recent disease onset showed flecks with very short autofluorescence lifetimes, which is possible evidence of accumulation of retinoids deriving from the visual cycle. During the study period, many of these flecks changed to longer lifetimes, possibly due to accumulation of lipofuscin. Therefore, FLIO might serve as a useful tool for monitoring of disease progression. (ClinicalTrials.gov number, NCT01981148.).

DIABETIC RETINOPATHY IN NON-INSULIN-DEPENDENT DIABETES MELLITUS IN BLACK WOMEN: A DESCRIPTIVE STUDY OF RISK FACTORS

This cross-sectional study examines the prevalence of selected potential risk factors by stage of diabetic retinopathy (DR) among Black American women with non-insulin-dependent diabetes mellitus (NIDDM) followed at a university diabetes clinic. DR was assessed by ophthalmoscopy and five-field retinography, and graded on counts of microaneurysms, hemorrhages and/or exudates, and presence of proliferative DR. Prevalence of other vascular diseases was assessed from medical records. Potential risk factors included age, known duration of diabetes, type of hypoglycemic treatment, concentrations of random capillary blood glucose, glycosylated hemoglobin, urine protein and fibrinogen, body mass index, and blood pressure. Prevalence of these risk factors is reported for three categories: No DR, mild background DR, severe background or proliferative DR (including surgically treated DR). Duration, age at diagnosis and treatment of diabetes, concentration of urine protein and average blood glucose, hypertension and cardiovascular disease were significantly associated with DR in univariate analysis. The covariance analysis employed stratification on duration, age at diagnosis and therapy of diabetes. The highest DR scores were calculated for those diagnosed before age 45, regardless of duration, therapy, or average blood glucose. Only individuals diagnosed before age 45 had high blood glucose concentrations in all categories of duration. These findings suggest that in this clinic population of Black women, those diagnosed with NIDDm before age 45 who eventually required insulin treatment were at the greatest risk of developing DR and that longterm poor glucose control is a contributing factor. These results suggest that greater emphasis be placed on this subgroup in allocating the limited resources available to improve the quality of glucose regulation, particularly through measures affecting compliance behavior.^ Findings concerning the association of DR with concentration of blood glucose and urine protein, blood pressure/hypertension and weight were compared with those reported from American Indian and Mexican American populations of the Southwestern United States where prevalence of NIDDM, hypertension and obesity is also high. Additional comparative analyses are outlined to substantiate the preliminary finding that there are systematic differences between these ethnic populations. ^

Long time remodeling during retinal degeneration evaluated by optical coherence tomography, immunocytochemistry and fundus autofluorescence

Purpose: To characterize the relationship between fundus autofluorescence (FAF), Optical Coherence Tomography (OCT) and immunohistochemistry (IHC) over the course of chronic retinal degeneration in the P23H rat. Methods: Homozygous albino P23H rats, Sprague–Dawley (SD) rats as controls and pigmented Long Evans (LE) rats were used. A Spectralis HRA OCT system was used for scanning laser ophthalmoscopy (SLO) imaging OCT and angiography. To determine FAF, fluorescence was excited using diode laser at 488 nm. A fast retina map OCT was performed using the optic nerve as a landmark. IHC was performed to correlate with the findings of OCT and FAF changes. Results: During the course of retinal degeneration, the FAF pattern evolved from some spotting at 2 months old to a mosaic of hyperfluorescent dots in rats 6 months and older. Retinal thicknesses progressively diminished over the course of the disease. At later stages of degeneration, OCT documented changes in the retinal layers, however, IHC better identified the cell loss and remodeling changes. Angiography revealed attenuation of the retinal vascular plexus with time. Conclusion: We provide for the first time a detailed long-term analysis of the course of retinal degeneration in P23H rats using a combination of SLO and OCT imaging, angiography, FAF and IHC. Although, the application of noninvasive methods enables longitudinal studies and will decrease the number of animals needed for a study, IHC is still an essential tool to identify retinal changes at the cellular level.

Prećis d'ophtalmoscopie vet́eŕinaire,

Bibliography: p. [117]-118.

Die Ophthalmoskopie in der Veterinär-Medicin /

Mode of access: Internet.

Augenheilkunde und Ophthalmoskopie : für Aerzte und Studirende /

Mode of access: Internet.

Panoptic versus conventional ophthalmoscope

Background: The 'ease of use' andaccuracy in measurement of the vertical optic cup/discratio (VCDR) was compared between the conventional direct ophthalmoscope(CO) and Panoptic direct ophthalmoscope (PO) in a group of 'naive' firstyear medical students to determine which would be more suitablefor non-ophthalmologists. Methods: In this quasi-randomized method comparison study,eight students received an introductory session on ophthalmoscopythen examined 18 eyes (9 left, 9 right) with each ophthalmoscopein a private practice. The subjects were the eight students themselvesplus two other subjects. Each subject (n = 10)had one eye dilated. Students determined a VCDR and a subjectivescore of 'ease of use' on a scale of 1 (difficult)to 10 (easy). A consultant ophthalmologist (GAG) determined thebenchmark VCDR for each eye with each ophthalmoscope. Results: Of 288 eye examinations, there were 111 measure-ments of VCDR using the CO (47 undilated, 64dilated), and 140 measurements using the PO (75 undilated, 65 dilated).Differences in the students' estimated VCDR and the benchmarkwere similar for the CO and PO (P = 0.67). 'Easeof use' was scored in 288 eyes and the median score washigher in the PO overall (CO: median 8, IQR 6-9; PO median9, IQR 8-10; P < 0.0001), andwithin each session (P < 0.0001 foreach session). Conclusions: Medical students found the PO mucheasier to use, with accuracy of rating the VCDR similar to the CO. Thiscomparison would support the wider use of the PO amongst medicalstudents, general practitioners and other primary care providers.

Topographic, haemodynamic and psychophysical investigation of glaucomatous optic neuropathy

Loss of optic nerve head (ONH) axons in primary open angle glaucoma (POAG) has been attributed to both mechanical and vascular factors. Confocal scanning laser ophthalmoscopy (cSLO) provides a promising tool for the topographic follow-up of the ONH in glaucoma, while scanning laser Doppler flowmetry (SLDF) facilitates the rapid non-invasive assessment of retinal capillary blood flow. The purposes of these investigations were to optimise the techniques and explore their potential to classify and monitor disease. Preliminary investigations explored the reproducibility and validity of cSLO and SLDF and showed that: For cSLO: In a model eye, measurements are accurate over a range of axial lengths. For best reproducibility, seven images per visit are required, with a contour line located on Elschnig's scleral ring and transferred automatically between images. For SLDF: Three perfusion images are required for optimum reproducibility. Physiological changes induced by gas perturbation can be measured. Cross-sectional comparison of groups of normal subjects and early POAG patients showed that: cSLO parameters differentiate the early POAG group. Blood volume measured by SLDF showed group differences in superior nasal retina only. Longitudinal investigation of ONH topography, haemodynamic and visual field indices in normal subjects and POAG patients showed that: cSLO detects topographical change over time more frequently in the POAG group. Important parameters include: C:D area ratio, cup and rim area, mean depth in contour, volumes above and below reference and surface. Factor analysis identified "cup" and "rim" factors that can be used to detect change over time in individual patients. Blood flow changes were most apparent in the inferior nasal peripapillary retina of the POAG group. Perimetry is of clinical value for the identification of glaucoma but is less sensitive than cSLO for monitoring glaucomatous change.

Objective and psychophysical studies of infant visual development

Distortion or deprivation of vision during an early `critical' period of visual development can result in permanent visual impairment which indicates the need to identify and treat visually at-risk individuals early. A significant difficulty in this respect is that conventional, subjective methods of visual acuity determination are ineffective before approximately three years of age. In laboratory studies, infant visual function has been quantified precisely, using objective methods based on visual evoked potentials (VEP), preferential looking (PL) and optokinetic nystagmus (OKN) but clinical assessment of infant vision has presented a particular difficulty. An initial aim of this study was to evaluate the relative clinical merits of the three techniques. Clinical derivatives were devised, the OKN method proved unsuitable but the PL and VEP methods were evaluated in a pilot study. Most infants participating in the study had known ocular and/or neurological abnormalities but a few normals were included for comparison. The study suggested that the PL method was more clinically appropriate for the objective assessment of infant acuity. A study of normal visual development from birth to one year was subsequently conducted. Observations included cycloplegic refraction, ophthalmoscopy and preferential looking visual acuity assessment using horizontally and vertically oriented square wave gratings. The aims of the work were to investigate the efficiency and sensitivity of the technique and to study possible correlates of visual development. The success rate of the PL method varied with age; 87% of newborns and 98% of infants attending follow-up successfully completed at least one acuity test. Below two months monocular acuities were difficult to secure; infants were most testable around six months. The results produced were similar to published data using the acuity card procedure and slightly lower than, but comparable with acuity data derived using extended PL methods. Acuity development was not impaired in infants found to have retinal haemorrhages as newborns. A significant relationship was found between newborn binocular acuity and anisometropia but not with other refractive findings. No strong or consistent correlations between grating acuity and refraction were found for three, six or twelve months olds. Improvements in acuity and decreases in levels of hyperopia over the first week of life were suggestive of recovery from minor birth trauma. The refractive data was analysed separately to investigate the natural history of refraction in normal infants. Most newborns (80%) were hyperopic, significant astigmatism was found in 86% and significant anisometropia in 22%. No significant alteration in spherical equivalent refraction was noted between birth and three months, a significant reduction in hyperopia was evident by six months and this trend continued until one year. Observations on the astigmatic component of the refractive error revealed a rather erratic series of changes which would be worthy of further investigation since a repeat refraction study suggested difficulties in obtaining stable measurements in newborns. Astigmatism tended to decrease between birth and three months, increased significantly from three to six months and decreased significantly from six to twelve months. A constant decrease in the degree of anisometropia was evident throughout the first year. These findings have implications for the correction of infantile refractive error.

The retinopathy of prematurity: a study of incidence and the identification of those babies at risk: myopia associated with prematurity

The ocular problems associated with premature birth have been with us ever since it was discovered that the application of high levels of inspired oxygen provided a reduction in mortality. The consequence of this reduction in mortality has been a rise in morbidity; these mortality and morbidity rates have oscillated during the attempt to find a reasonable balance. The use of contemporary technology during the attempt both to understand the premature baby's delicate physiology and to maintain life to younger and lighter babies has not yet produced stability. The incidence of typical retinal maldevelopment, retinopathy of prematurity (RCP), was analysed by serial weekly ophthalmoscopy examinations in a regional special care baby unit, 579 examinations being made on 138 babies. The best instrument for this examination was found to be a compact indirect ophthalmoscope incorporating an inverting eyepiece - the Reichert Jung monocular indirect ophthalmoscope. The optimum time for ocular examination to discover potential ocular morbidity was at 33 weeks post-conceptual age (PCA) with continued examinations to the age of 37 weeks PCA. The babies that were found to be at risk of a significant grade of RCP were found to be of a birth weight of less than 1251 grams or had an estimated gestational age at birth of 30 weeks or less. A refractive state of myopia was found to be the norm. The myopia reduced as life progressed to attain emmetropia around the age of 50 weeks PCA or 22 weeks survival. The reduction of the myopic state was found to be dependent on birth weight and gestational age at birth, the youngest and therefore the lightest being more predictable in attaining emmetropia. Refractive variations were found to be coincident with the timings of certain medical treatment regimes and a hypothesis is postulated as to the mechanism of this association.

Spontanoeusly resolved macroaneurysm associated with a congenital anomalous retinal artery

Purpose: To report the outcome of retinal artery macroaneurysm associated with a congenital anomalous retinal artery. Methods: The patient was examined with ophthalmoscopy and fluorescein angiography. Results: A 60-year-old woman presented with visual acuity of 20/80 in her right eye. She was found to have an abnormal retinal vessel emerging from the optic disk, passing toward the center of the macula, and looping back toward the disk. The center of the loop had a leaking macroaneurysm, which was treated conservatively. At the 4-month follow-up visit, the visual acuity in the right eye had improved to 20/20 with resolution of most of the macular edema, exudates, and hemorrhage. Conclusion: This case demonstrates that retinal artery macroaneurysm can be successfully managed with a conservative approach, even when associated with a congenital anomalous retinal vessel.