Endoscopic Vitreoretinal Surgery; Basic Principles, Indications and New Directions

In this review, we aimed to give information about the historical development, basic features, and major indications of microendoscopy in vitreoretinal surgery. Microendoscopy permits vitreoretinal surgery for tissues that are not visible using operating microscopy ophthalmoscopy. Evolving technology may overcome the technical limitations of current endoscopic technology. Endoscopic vitreoretinal surgery is particularly useful when tissue details blurred by ocular media opacities or anterior chamber aberrations in contemporary surgical microscopic ophthalmoscopy. Microendoscopy is a robust platform for vitreoretinal surgery. Ophthalmic microendoscopy as a complementary method to modern vitreoretinal surgical techniques is very useful for safe surgery when an operating a microscope becomes insufficient.

Lens and cornea limit UV vision of birds – a phylogenetic perspective

Most vertebrates have UV-sensitive vision, but the UV-sensitivity of their eyes is limited by the transmittance of the ocular media, and the specific contribution of the different media (cornea, lens) has remained unclear. Here we describe the transmittance of all ocular media (OMT), as well as that of lenses and corneas of birds. For 66 species belonging to 18 orders, the wavelength at which 50% of light is transmitted through the ocular media to the retina (λT0.5) ranges from 310 to 398 nm. Low λT0.5 corresponds to more UV-light transmitted. Corneal λT0.5 varies only between 300 and 345 nm, whereas lens λT0.5 values are more variable (between 315 and 400 nm) and tend to be the limiting factor, determining OMT in the majority of species. OMT λT0.5 is positively correlated with eye size, but λT0.5 of corneas and lenses are not correlated with their thickness when controlled for phylogeny. Corneal and lens transmittances do not differ between birds with UV- and violet-sensitive SWS1 opsin when controlling for eye size and phylogeny. Phylogenetic relatedness is a strong predictor of OMT, and ancestral state reconstructions suggest that from ancestral intermediate OMT, highly UV-transparent ocular media (low λT0.5) evolved at least five times in our sample of birds. Some birds have evolved in the opposite direction towards a more UV-opaque lens, possibly due to pigmentation, likely to mitigate UV-damage or reduce chromatic aberration.

Monocular Diplopia in Idiopathic Intracranial Hypertension: A Case Report and Literature Review

Background: Diplopia is the double vision of a single object, and can be binocular or monocular. Binocular diplopia is caused by the misalignment of the visual axes, with images falling on the fovea of the fixating eye and on the extra-foveal retina of the non-fixating eye, as a consequence of both neurological (i.e., oculomotor nerve palsies, ocular myopathies, neuromuscular junction disorders) and ophthalmic disorders (i.e., decompensation of a pre-existing strabismus). In contrast, monocular diplopia is generally explained by intraocular pathology (i.e., refractive errors, ocular media abnormalities, dry eyes), causing the image of a single object to fall, at the same time, on the fovea and on the extra-foveal retina of the same eye. Methods: We report the case of a 22-year-old woman presenting with acute-onset monocular diplopia. Results: The diagnosis of idiopathic intracranial hypertension (IIH) was based on the presence of papilloedema and elevated cerebrospinal fluid (CSF) pressure. Monocular diplopia resolved after CSF subtraction. Conclusions: We describe a case of monocular diplopia as a presenting symptom of IIH, and discuss diagnostic issues of this possibly underestimated symptom in neurology clinical practice. Careful ophthalmic and neuro-ophthalmic examination can identify clinical features of diplopia, and drive diagnosis and treatment.

Oral Ursodeoxycholic Acid Crosses the Blood Retinal Barrier in Patients with Retinal Detachment and Protects Against Retinal Degeneration in an Ex Vivo Model

Rhegmatogenous retinal detachment (RD) is a threatening visual condition and a human disease model for retinal degenerations. Despite successful reattachment surgery, vision does not fully recover, due to subretinal fluid accumulation and subsequent photoreceptor cell death, through mechanisms that recapitulate those of retinal degenerative diseases. Hydrophilic bile acids are neuroprotective in animal models, but whether they can be used orally for retinal diseases is unknown. Ursodeoxycholic acid (UDCA) being approved for clinical use (e.g., in cholestasis), we have evaluated the ocular bioavailability of oral UDCA, administered to patients before RD surgery. The level of UDCA in ocular media correlated with the extent of blood retinal barrier disruption, evaluated by the extent of detachment and the albumin concentration in subretinal fluid. UDCA, at levels measured in ocular media, protected photoreceptors from apoptosis and necrosis in rat retinal explants, an ex vivo model of RD. The subretinal fluid from UDCA-treated patients, collected during surgery, significantly protected rat retinal explants from cell death, when compared to subretinal fluid from control patients. Pan-transcriptomic analysis of the retina showed that UDCA upregulated anti-apoptotic, anti-oxidant, and anti-inflammatory genes. Oral UDCA is a potential neuroprotective adjuvant therapy in RD and other retinal degenerative diseases and should be further evaluated in a clinical trial.

Retinal Sensitivity and Ganglion Cell-Related Retinal Layer Thickness in the Normal Aging Process

Aging-associated changes in visual field (VF) sensitivity were compared prospectively and longitudinally with the circumpapillary retinal nerve fiber layer thickness (cpRNFLT) and macular ganglion cell-inner plexiform layer thickness (GCIPLT) changes in the corresponding retinal areas of the same eyes (72 eyes of 37 normal Japanese subjects; mean age, 51.3 years). The Humphrey Field Analyzer 24-2 test (HFA 24-2) and spectral-domain optical coherence tomography (SD-OCT) measurements of the cpRNFLT and GCIPLT in a 0.6-mm-diameter circle corresponding to the four central points of HFA 24-2 adjusted for retinal ganglion cell displacement (GCIPLT4TestPoints) were performed every 3 months for 3 years. The tiem changes of the mean sensitivity over the entire field (VFmean) and the four central points (VF4TestPoints), cpRNFLT, and GCIPLT4TestPoints were analyzed using a linear mixed model. The aging-associated decline rates of VFmean and VF4TestPoins were 0.12 and 0.19 decibels/year (p<0.001), which significantly accelerated with increased subjects’ age (0.009 and 0.010 decibels/year, p<0.001, respectively) without changes in the ocular media. Those of the CpRNFLT and GCIPLT4TestPoints were not significant in both (p>0.114), but significantly accelerated with increased subjects’ age (0.021 and 0.010 mm/year, p=0.001 and 0.004, respectively). These results have implications in studying physiological aging- or desease-related changes in these parameters.

Transmittance measurement of the in vivo human eye with a double-pass system

Purpose: To develop a methodology based on a double-pass system to obtain information about the transmittance of ocular media. Methods: The procedure consists of recording double-pass images at different powers of a laser diode of 780 nm and determining the scattering in an area between 25–35 arcmin of each image. The scattering showed linear behavior in respect to the irradiance of the laser, and the slope of the linear fit was proportional to the transmittance squared of the media evaluated. An artificial eye with different filters was tested first. Then, fifteen subjects with clear ocular media were divided into two groups: ten subjects classified by the iris color were recruited for the measurements of an ocular transmittance index and the estimation of the transmittance (group A), and another five subjects were selected for measurements with neutral filters (group B). Results: The measurements performed in group A presented a mean transmittance of 42.95%. No differences in the transmittance were found between subjects with different iris color (p = 0.154). Measurements in group B showed a good correlation (r = 0.959, p < 0.001) between the expected and the measured value for the transmittance. Conclusion: We proposed and evaluated a method to determine the transmittance of the eye in vivo using the double-pass system.

Retinal laser photocoagulation in management of eales' disease

Eales’ disease is an idiopathic occlusive inflammatory vasculopathy resulting in peripheral retinal ischemia, neovascularization, recurrent hemophthalmos, and proliferative tissue formation. It is often complicated by tractional retinal detachment, secondary glaucoma, and central retinal vein occlusion. The management of patients with Eales’ disease includes mainly glucocorticosteroid therapy, the use of angiogenesis inhibitors, vitreoretinal surgery and laser photocoagulation. The clinical case reported demonstrates the potential of retinal laser photocoagulation for treatment of the Eales’ disease in the ischemic and proliferative stages. The results of retinal laser photocoagulation used as monotherapy demonstrate the clinical and functional indices improvement: enhanced visual acuity, stabilized central retinal sensitivity value, restored clarity to the ocular media, regression of neovascularization and macular edema in the patient’s eye being in the proliferative (3b) stage, and the process stabilization in the eye being in the ischemic (2a) stage of the disease.

Lens transmittance shapes ultraviolet sensitivity in the eyes of frogs from diverse ecological and phylogenetic backgrounds

The amount of short wavelength (ultraviolet (UV), violet and blue) light that reaches the retina depends on the transmittance properties of the ocular media, especially the lens, and varies greatly across species in all vertebrate groups studied previously. We measured the lens transmittance in 32 anuran amphibians with different habits, geographical distributions and phylogenetic positions and used them together with eye size and pupil shape to evaluate the relationship with diel activity pattern, elevation and latitude. We found an unusually high lens UV transmittance in the most basal species, and a cut-off range that extends into the visible spectrum for the rest of the sample, with lenses even absorbing violet light in some diurnal species. However, other diurnal frogs had lenses that transmit UV light like the nocturnal species. This unclear pattern in the segregation of ocular media transmittance and diel activity is shared with other vertebrates and is consistent with the absence of significant correlations in our statistical analyses. Although we did not detect a significant phylogenetic effect, closely related species tend to have similar transmittances, irrespective of whether they share the same diel pattern or not, suggesting that anuran ocular media transmittance properties might be related to phylogeny.

Lens Transmittance Shapes UV Sensitivity in the Eyes of Frogs from Diverse Ecological and Phylogenetic Backgrounds

ABSTRACTThe amount of short wavelength (UV, violet and blue) light that reaches the retina depends on the transmittance properties of the ocular media, especially the lens, and varies greatly across species in all vertebrate groups studied previously. We measured the lens transmittance in 32 anuran amphibians with different habits, geographic distributions, and phylogenetic positions and used them together with eye size and pupil shape to evaluate the relationship with diel activity pattern, elevation and latitude. We found an unusually high lens UV transmittance in the most basal species, and a range that extends into the visible spectrum for the rest of the sample, with lenses even absorbing violet light in some diurnal species. However, other diurnal frogs had lenses that transmit UV light like the nocturnal species. This unclear pattern in the segregation of ocular media transmittance and diel activity is shared with other vertebrates and is consistent with the absence of significant correlations in our statistical analyses. Although we did not detect a significant phylogenetic effect, closely related species tend to have similar transmittances, irrespective of whether they share the same diel pattern or not, suggesting that ocular media transmittance properties might be related to phylogeny.