Ciro Tamburrelli

Convergent strabismus fixus in high myopic patients.

Patients with high myopia may develop a myopathy which frequently results in a sort of convergent strabismus fixus. Echographic and CT scan findings give evidence that a myopathic paralysis of the lateral rectus is supported by a slow pressure on this muscle squeezed between the lateral orbital wall and the enlarged eyeball.

The Pathogenesis of Retinal Damage in Blunt Eye Trauma: Finite Element Modeling

PURPOSE To test the hypothesis that blunt trauma shockwave propagation may cause macular and peripheral retinal lesions, regardless of the presence of vitreous. The study was prompted by the observation of macular hole after an inadvertent BB shot in a previously vitrectomized eye. METHODS The computational model was generated from generic eye geometry. Numeric simulations were performed with explicit finite element code. Simple constitutive modeling for soft tissues was used, and model parameters were calibrated on available experimental data by means of a reverse-engineering approach. Pressure, strain, and strain rates were calculated in vitreous- and aqueous-filled eyes. The paired t-test was used for statistical analysis with a 0.05 significance level. RESULTS Pressure at the retinal surface ranged between -1 and +1.8 MPa at the macula. Vitreous-filled eyes showed significantly lower pressures at the macula during the compression phase (P < 0.0001) and at the vitreous base during the rebound phase (P = 0.04). Multiaxial strain reached 20% and 25% at the macula and vitreous base, whereas the strain rate reached 40,000 and 50,000 seconds(-1), respectively. Both strain and strain rates at the macula, vitreous base, and equator reached lower values in the vitreous- compared with the aqueous-filled eyes (P < 0.001). Calculated pressures, strain, and strain rate levels were several orders of magnitude higher than the retina tensile strength and load-carrying capability reported in the literature. CONCLUSIONS Vitreous traction may not be responsible for blunt trauma-associated retinal lesions and can actually damp shockwaves significantly. Negative pressures associated with multiaxial strain and high strain rates can tear and detach the retina. Differential retinal elasticity may explain the higher tendency toward tearing the macula and vitreous base.

Optic nerve diameters and perimetric thresholds in idiopathic intracranial hypertension.

AIMS/BACKGROUND--Idiopathic intracranial hypertension (IIH) is a central nervous disorder characterised by abnormally increased cerebrospinal fluid (CSF) pressure leading to optic nerve compression. An indirect estimate of increased CSF pressure can be obtained by the ultrasonographic determination of optic nerve sheaths diameters. Computerised static perimetry is regarded as the method of choice for monitoring the course of the optic neuropathy in IIH. The aims were to compare the echographic optic nerve diameters (ONDs) and the perimetric thresholds of patients with IIH with those of age-matched controls, and to examine the correlation between these two variables in individual patients with papilloedema. METHODS--Standardised A-scan echography of the mid orbital optic nerve transverse diameters and automated threshold perimetry (Humphrey 30-2) were performed in 20 patients with IIH with variable degree of papilloedema (according to the Frisén scheme) and no concomitant ocular diseases. Echographic and perimetric results were compared with those obtained from 20 age-matched controls. RESULTS--When compared with controls, patients with IIH showed a significant increase in mean ONDs and significantly reduced mean perimetric sensitivities. In individual patients with papilloedema, the transverse ONDs correlated negatively with Humphrey mean deviation values and positively with pattern standard deviation values. CONCLUSION--These results indicate that OND changes in IIH are associated with perimetric threshold losses, and suggest that IIH functional deficits may be related to the degree of distension of optic nerve sheaths as a result of an increased CSF pressure.

A new device for ocular surgical training on enucleated eyes

OBJECTIVE To develop a reliable inexpensive device for teaching ocular surgical procedures and practicing experimental techniques on enucleated eyes. DESIGN Teaching device trial. PARTICIPANTS Thirty enucleated porcine eyes. METHODS A Plexiglas ocular bulb holder was secured with its base support to a polyvinylchloride pillar on a modified polystyrene trial head. MAIN OUTCOME MEASURE The convenience and reproducibility of both laser and surgical ocular techniques performed with this new device were evaluated. RESULTS This model allows curvilinear capsulorrhexis and phacoemulsification of porcine lenses through a corneal tunnel incision and insertion of a soft foldable acrylic intraocular lens into the capsular bag. Argon and neodymium:YAG laser iridotomy and retinal argon laser photocoagulation can also be performed with this model. CONCLUSIONS This inexpensive device is useful for teaching both surgical and laser ocular procedures.

Restrictive Limitation of Sursumduction Caused by an Anomalous Muscular Structure

We report a peculiar case of congenitally restricted sursumduction caused by an anomalous band-like structure within the right orbit which was completely distinct from the extraocular muscles. Imaging (static and dynamic ultrasound studies of the orbit and globe, CT and MRI) revealed the origin of the anomalous structure in Zinn’s ring, its intraconal course and bulbar insertion. The ultrasound characteristics were similar to those of the extraocular muscles and optic nerve, and contractile activity appeared to occur during eye movements. The seemingly muscular nature of this structure and its total autonomy with respect to the normal extraocular muscles distinguish this case from previously reported cases of congenital restrictive strabismus.

Choroidal hemorrhage drainage through 23-gauge vitrectomy cannulas.

Choroidal Hemorrhage Drainage Through 23-Gauge Vitrectomy Cannulas Choroidal effusion syndrome (CES) and suprachoroidal hemorrhage (SCH) are rare but dreaded complications of virtually every intraocular procedure,1 including cataract, glaucoma surgery, penetrating keratoplasty, scleral buckles, and vitrectomy.2 They may also spontaneously arise in hypertensive and/or vasculopathic patients.3 Treatment of CES and SCH is still largely debated and includes a more conservative pharmacologic approach and surgical drainage occasionally combined with pars plana vitrectomy (PPV) and tamponade.4 Small-gauge transconjunctival PPV was introduced in 20025 as a niche surgical technique devoted to “minimal surgery,” mostly macular puckers, macular holes, diagnostic vitrectomy, and other minor vitreal procedures.6 Ever since, small-gauge transconjunctival PPV indications have greatly expanded because of armamentarium refinement and surgical skill improvement. Today, small-gauge transconjunctival PPV encompasses the entire spectrum of vitreous surgery, from diabetic retinopathy to proliferative vitreoretinopathy and trauma cases.7 The purpose of this article was to report the cases of 3 consecutive patients with CES and/or SCH surgically drained by means of 23-gauge (23G) vitrectomy cannulas combined with 23G PPV and silicone oil (SiO) tamponade.

Wedge-shaped light pipe aperture for pars plana vitrectomy.

Indications to pars plana vitrectomy have largely expanded, and today what was once considered heroic surgery is routinely performed. Nonetheless, bringing a bright, efficient, yet safe1– 4 illumination to the posterior segment of the eye remains a challenge. The detection of semitransparent structures such as the vitreous, retinal membranes, heme, and the retina itself, in fact, entirely depends on their differential illuminance.5 Currently available light sources offer a variety of wavelengths and intensities,6 –10 whereas light pipe aperture geometry is limited to the regular “straight” and the “bullet” variants.11 The former projects a narrower beam, yielding a more favorable “Tyndall effect,” whereas the latter allows a wider illumination angle, ideal for panoramic viewing. The purpose of this article is to introduce prototype wedge-shaped aperture light pipes (WSAL), intended to provide a compromise between a wider angle of illumination and a “focused” beam of light with more favorable scattering and limited surgeon dazzling.

Conservative Treatment of Adnexal, Epibulbar and Intraocular Neoplasms by Means of Electron Microbeams: A Preliminary Study

At present, episcleral plaque brachytherapy and charged particle or photon irradiation are the most commonly employed methods in ocular and adnexal conservative treatments. In the near future, a different therapeutic approach to these malignancies could be represented by a new device based on electron beam emission. The equipment used consists of an electron accelerator originally developed for intraoperative radiotherapy, modified to fit ocular pathologies. Adequate collimators and an enhanced mechanical accuracy are required for this special practice. An operative planning for epibulbar, adnexal and intraocular tumors is described, discussing its rationale for possible applications. Experimental tests using phantoms and Gafchromic® films are in progress. As all conservative treatments, the main gaol of this activity is the maintenance of a good visual function.

Intracoital subfoveal hemorrhage after tadalafil (cialis) premedication: a case report.

PURPOSE The purpose of this study is to report the first case, to our knowledge, of intracoital subfoveal hemorrhage occurring 1 hour after tadalafil premedication in a patient with previously undiagnosed retinal angiomatous proliferation and erectile dysfunction. METHODS This is an interventional case report. The patient underwent Snellen vision acuity measurement, anterior and posterior segment biomicroscopy, and indirect ophthalmoscopy. Optical coherence tomography, fluorescein angiography, and indocyanine green angiography were also performed as needed. Recombinant tissue plasminogen activator 100 μg/0.1 mL and 0.3 mL pure SF6 gas were injected in the vitreous on presentation. Four days later, the patient received 1.25 mg/0.1 mL of intravitreal bevacizumab. RESULTS One day after recombinant tissue plasminogen activator and gas injection, visual acuity rose to 20/60-2. A week later, visual acuity was unchanged, and the subretinal hemorrhage displaced from the foveola. Optical coherence tomography showed a marked regression of submacular thickening. CONCLUSION Despite strict time correlation, the submacular hemorrhage cannot be unequivocally attributed to tadalafil assumption because many other risk factors are to be considered: the Valsalva maneuver above all. Nonetheless, a suspicion should be raised, at least as a cofactor, given the drug mechanism of action and the report of vascular abnormalities bleeding in the literature, including cerebral arterovenous malformation and epistaxis. Caution should be exercised in the prescription of phosphodiesterase type 5 inhibitors to patients with known vascular abnormalities including retinal and choroidal abnormalities: retinal angiomatous proliferation, classic and occult neovascularization of any origin, and also, possibly, hemangioma.

Book Review · Livre nouveau · Buchbesprechung

This book deals with animal studies on corneal graft rejection. The introduction presents the current state of knowledge of allograft reaction after experimental keratoplasty and focuses on immunomodulated therapy with encapsulated monoclonal antibodies (mAb) in local application. In the second chapter, the goals and reasons for a study on the prevention of allograft rejection by local treatment with mAb are given in the form of four questions: (1) can locally applied CD4 mAb affect graft reaction after penetrating keratoplasty? (2) are liposome-incorporated CD4 mAb more effective? (3) do locally applied CD4 mAb have a systemic effect? (4) does the recipient react systemically against graft antigens and are in vitro tests meaningful for clinical grafts? Materials, methods and results are clearly described in the third and fourth chapters. In an experimental model of penetrating keratoplasty in rat eyes, anti-CD4 mAb were injected subconjunctivally or applied as drops in two different forms of administration selected for free mAb in a first test series and liposome-encapsulated mAb in a second. The results of liposome-encapsulated mAb application showed a declining incidence of immunologic graft reactions after subconjunctival injection and also after drop application. The controls showed no effects. A systemic effect on CD4+ lymphocytes could be excluded by flow cytometry. The cytotoxic T lymphocyte activity tested by antigen-specific cytotoxic T lymphocyte in vitro tests was significantly elevated after allograft reactions as an indication of specific sensitization. In contrast to this, no delayed-type hypersensitivity response was observed in the present study. These results are discussed in detail in the fifth chapter. In summary, the results described in this book open up new perspectives for preventing allograft reactions after keratoplasty by local application of liposome-encapsulated specific mAb. These exciting animal results should proceed to clinical trials in the near future.