[The Boston keratoprosthesis in the management of corneal blindness: Indications and limitations]. / La kératoprothèse de Boston dans la prise en charge de la cécité cornéenne : intérêts et limites.

INTRODUCTION: Keratoprostheses offer a therapeutic alternative to patients with bilateral corneal blindness who cannot undergo corneal allograft. The goal of this work was to evaluate the indications and limitations of Boston keratoprosthesis. MATERIALS AND METHODS: Seven patients underwent unilateral implantation of a Boston type I keratoprosthesis between December 2012 and November 2016. The following data were collected: surgical indication, preoperative visual acuity, postoperative visual acuity at D1, D7, D30, 6 months and 12 months, complications and postoperative treatment. RESULTS: The mean age of implantation was 58.7±23.4 years. The surgical indications included 1 case of congenital bilateral aniridia, 2 cases of chemical burn and 4 graft decompensations after multiple keratoplasties. Preoperative visual acuity was limited to "light perception" in 6 cases and "hand motion" in one case. A gain in visual acuity was observed in 4 patients, which corresponded to a mean gain of 1.53 logMAR at last follow-up. Postoperative visual acuity averaged 2.33 logMAR. All patients experienced an improvement in their quality of life and independence. DISCUSSION: Patients should be selected carefully, favoring patients with a remaining functional potential and able to engage in close postoperative follow-up, in order to ensure the best possible treatment success. CONCLUSION: Boston keratoprosthesis provides improved vision and improved quality of life for patients suffering from bilateral corneal blindness.

Visual cortical prosthesis with a geomagnetic compass restores spatial navigation in blind rats.

Allocentric sense is one of the major components that underlie spatial navigation. In blind patients, the difficulty in spatial exploration is attributed, at least partly, to the deficit of absolute direction perception. In support of this notion, we announce that blind adult rats can perform spatial tasks normally when externally provided with real-time feedback of their head directions. Head-mountable microstimulators coupled with a digital geomagnetic compass were bilaterally implanted in the primary visual cortex of adult rats whose eyelids had been sutured. These "blind" rats were trained to seek food pellets in a T-shaped maze or a more complicated maze. Within tens of trials, they learned to manage the geomagnetic information source to solve the mazes. Their performance levels and navigation strategies were similar to those of normal sighted, intact rats. Thus, blind rats can recognize self-location through extrinsically provided stereotactic cues.

A preliminary descriptive analysis of Corneal Transplant Registry of National Eye Bank in India.

PURPOSE: To describe and analyze the Corneal Transplant Registry of National Eye Bank and also evaluate graft outcomes in India. METHODS: All patients who underwent corneal transplant at our center within six months of setting up of Corneal Transplant Registry and installation of database at National Eye Bank were included in the study. The established database was analyzed for utilization, donor and recipient details and graft outcomes. Outcome was assessed at the end of one year follow up. The influence of various donor and recipient factors affecting outcome were evaluated. Visual outcome was analyzed in terms of shift in visual handicap category. Statistical tests like analysis of variance, Kruskal-Wallis test and Chi square tests were applied for determination of clinical significance wherever required. RESULTS: 326 corneas were received from 168 donors; of these, 234 (71.7%) were utilized for transplantation. Out of 177 patients with adequate (one year) follow up (75.6% patients), optical corneal replacement was performed in106 patients and therapeutic keratoplasty in71. 78% (82/106) patients in the optical group retained clear grafts at the end of follow up. 59.7% (49 of 82) of patients who attained clear grafts belonged to visual disability category 3 or worse pre-operatively. 59.1% of these achieved BCVA of ≥6/60 at the end of follow up; thus shifting up their visual handicap category. Primary graft failure was found to be associated with full thickness keratoplasty and not with lamellar procedures (p<0.05) and occurred in 4.2% patients (5) with optical corneal replacement whereas 7.5% patients (8) developed secondary graft failure. Age of donor (p=0.54), death enucleation time (p>0.05), cause of donor death (p=0.15), type of surgical procedures (p=0.538) and indication for surgery did not have any significant effect on outcome. 76% patients who underwent therapeutic graft achieved elimination of corneal infection. CONCLUSIONS: The development of corneal graft registry established an effective means to evaluate our corneal transplantation services. Outcomes of sight restoring corneal transplants performed were comparable to results of graft registries from developed nations.

The Detection of Motion by Blind Subjects With the Epiretinal 60-Electrode (Argus II) Retinal Prosthesis.

OBJECTIVE: To investigate the ability of 28 blind subjects implanted with a 60-electrode Argus II (Second Sight Medical Products Inc) retinal prosthesis system to detect the direction of a moving object. METHODS: Blind subjects (bare light perception or worse in both eyes) with retinitis pigmentosa were implanted with the Argus II prosthesis as part of a phase 1/2 feasibility study at multiple clinical sites worldwide. The experiment measured their ability to detect the direction of motion of a high-contrast moving bar on a flatscreen monitor in 3 conditions: with the prosthesis system on and a 1-to-1 mapping of spatial information, with the system off, and with the system on but with randomly scrambled spatial information. RESULTS: Fifteen subjects (54%) were able to perform the task significantly better with their prosthesis system than they were with their residual vision, 2 subjects had significantly better performance with their residual vision, and no difference was found for 11 subjects. Of the 15 better-performing subjects, 11 were available for follow-up testing, and 10 of them had significantly better performance with normal rather than with scrambled spatial information. CONCLUSIONS: This work demonstrates that blind subjects implanted with the Argus II retinal prosthesis were able to perform a motion detection task they could not do with their native vision, confirming that electrical stimulation of the retina provides spatial information from synchronized activation of multiple electrodes. TRIAL REGISTRATION: clinicaltrials.gov Identifier:NCT00407602

Osseous metaplasia with formation of hematopoietic bone marrow in a blind, painful eye.

A 31-year-old woman underwent an evisceration of her blind, painful right eye with placement of an aluminum oxide orbital implant. Histopathologic assessment revealed functional hematopoietic bone marrow, confirmed by immunohistochemistry, within osseous metaplasia of the retinal pigment epithelium. This finding is exceedingly rare, with few cases reported in the English literature. This report raises numerous questions, including the association between pain and hematopoietic bone marrow formation, the potential benefits of hematopoietic bone marrow in the eye, and the molecular biologic basis for this rare phenomenon.

Ipsilateral globe penetration and transient contralateral amaurosis following retrobulbar anesthesia.

PURPOSE: To report a rare complication of retrobulbar anesthesia with ipsilateral globe penetration and transient contralateral amaurosis. DESIGN: Interventional case report. METHODS: A 63-year-old woman complained of vision loss in the right eye immediately following cataract surgery on the left eye. RESULTS: Right eye vision decreased to no light perception with clear media and normal fundus. The vision recovered to baseline in 12 hours. Left eye vision was checked and demonstrated only light perception. Fundus examination disclosed preretinal and vitreous hemorrhage. During vitrectomy of the left eye, a penetrating wound below the optic disk with retinal detachment was found. CONCLUSION: The ipsilateral globe penetration wound depicts the mechanism of contralateral amaurosis following retrobulbar anesthesia of the case.

Carotid arterial surgery using local anesthesia: a private practice retrospective study.

Carotid endarterectomy has recently become one of the more controversial operations. The tremendous increase in the number of endarterectomies performed, coupled with the apparent increase in morbidity and mortality associated with this operation in some studies, have brought into question the indications and results of the procedure. The potential for complications from the procedure itself, as well as increased morbidity and mortality from surgery on the elderly, make carotid endarterectomy a dangerous operation that must be done carefully and thoughtfully. The authors have performed carotid endarterectomies exclusively under local anesthesia to more closely evaluate the neurologic status of the patient. They believe that the operation performed in this manner obviates the use of a shunt and its inherent complications in greater than 80 per cent of the patients. This, coupled with the fact that many of the patients also have severe cardiac disease and the use of local anesthesia causes less hemodynamic changes and stress, should make carotid endarterectomy under local anesthesia the preferred approach.

Causes of blindness among students in blind school institutions in a developing country.

Out of 270 students in 17 blind school institutions in Malawi 73 per cent were blind before the age of three. The most common cause for the blindness was ocular infection (75-2 per cent). Meales, as a single cause, was responsible for 43-7 per cent of the cases and smallpox for 5-2 per cent. Bacterial infections were incriminated in 26-3 per cent of the cases. Most of these had received traditional medicine during the acute phase of the disease. Hereditary factors as causes of blindness were found in 7-8 per cent of the cases. These included congenital cataracts (2-6 per cent), optic atorphy of unknown origin (3-0 per cent), microphthalmos (1-5 per cent), and macular degeneration (0-7 per cent). Careful ophthalmological examination showed that in 37 cases an intervention could be attempted in order to improve the vision. In the 11 most favourable cases this was attempted, with the result that nine cases gained a useful vision of 4/60 to 6/18 in the better eye.

Vitrectomy: a new challenge for the anesthesiologist.

A new surgical procedure, virtectomy, for alleviation of blindness caused by previously intractable vitreous disease, is described. Special demands of vitrectomy upon the anesthesiologist are enumerated. Problems presented by a patient population, 83 percent of whom suffered from severe diabetes mellitus and/or hypertension with a variety of complications, are discussed. Anesthetic technic used for 47 patients undergoing vitrectomy is described.