Consultation section: refractive surgical problem.
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Journal Article↗
Biomedical subjects
S Esquenazi
Publications and source records attributed to S Esquenazi.
Robot-assisted microsurgery: a feasibility study in the rat.
OBJECTIVE: Telerobotic surgery is a novel technology that can improve a surgeon's manual dexterity as well as the results achieved with microsurgical procedures. METHODS: A prototype Robot-Assisted MicroSurgery (RAMS) microdexterity enhancement system developed by the Jet Propulsion Laboratory and MicroDexterity Systems, Inc., was tested in 10 rats. Carotid arteriotomies were created and closed using either the RAMS system or conventional microsurgical techniques. The time required, the technical quality (vessel patency and suture line integrity), the error rate, and subjective difficulty were compared. RESULTS: All procedures were successfully completed using the RAMS system to manipulate the vessel but not to hold the needle or place the sutures. The precision, technical quality, and error rate of telerobotic surgery were similar to those of conventional techniques. However, the use of the RAMS system was associated with a twofold increase in the length of the procedure. CONCLUSION: Surgery using a microdexterity enhancement system, or RAMS prototype, is feasible. With further development, such as a stereotelevisualization and haptic feedback system, this system could be used for telerobotic surgery in neurosurgical practice.
Animals↗
Cerebral cortical neuron apoptosis after mild excitotoxic injury in vitro: different roles of mesencephalic and cortical astrocytes.
OBJECTIVE: Increasing evidence supports the presence of neuronal apoptosis after ischemic or excitotoxic brain injury. Astrocytes, which exhibit significant regional differences in function, may exert a protective effect on neurons exposed to ischemic injury. We examined the effects of astrocytes derived from different regions of the central nervous system on neuronal apoptosis after mild excitotoxic injury in tissue culture. METHODS: Purified astrocyte cultures derived from P4 rat cerebral cortex or mesencephalon showed transient cell swelling but no cell death when exposed to 50 micromol/L glutamate for 5 minutes. When mixed neuronal/glial cocultures were exposed to the same glutamate dose, neuron death was observed. Necrotic and apoptotic cell death during 24 hours was examined using morphological criteria, nuclear staining, triphosphate nick end labeling, and trypan blue exclusion. RESULTS: We found that cortical neurons that elaborate a more extensive dendritic arbor when grown on homotypic astrocytes are more likely to undergo apoptosis than neurons with a limited dendritic arbor grown on heterotypic astrocytes. By contrast, a similar number of neurons undergo necrotic cell death. CONCLUSION: This finding may be associated with 1) increased vulnerability of neurons with a more elaborate dendrite structure to mild excitotoxic injury, or 2) regional differences in the ability of astrocytes to attenuate apoptosis.
Animals↗
Surgical treatment of human bites of the upper eyelid.
Human bites of the upper eyelid are extremely rare. Few reports have been published on the surgical management of such injuries, and they have dealt mainly with those cases in which the avulsed tissue segment is available for reconstructive surgery. This article reports on a case of human bite injury of the upper eyelid with more than 50% full-thickness loss of tissue, in which the missing segment was not available for reconstruction.
Adolescent↗
Comparison of laser in situ keratomileusis and automated lamellar keratoplasty for the treatment of myopia.
BACKGROUND: Automated lamellar keratoplasty (ALK) and laser in situ keratomileusis (LASIK) are surgical procedures used to correct high myopia, although their differences in effectiveness and long-term stability have not been sufficiently documented. Little information exists about the results of the two procedures in the hands of the same surgeon. METHODS: To assess long-term stability of refractive results of ALK and LASIK, a retrospective study of 260 eyes that received ALK and 308 eyes that received LASIK was undertaken. The mean follow-up was 1.8 years for ALK and 1.4 years for LASIK. RESULTS: The mean baseline spherical equivalent refraction in ALK eyes was -14.30 +/- 2.05 D (range -5 to -25 D) and in LASIK eyes was -8.50 +/- 1.75 D (range -3 to -26 D). At 3 months after surgery, 65 ALK eyes (25%) were within +/- 1.00 D of intended correction compared with 269 LASIK eyes (87.5%). At 1 year, only 31 ALK eyes (16%) were within +/- 1.00 D of intended correction, compared with 224 eyes (82%) in the LASIK group. At 3 months after surgery, the mean spherical equivalent refraction was -2.64 D in ALK eyes; at 1 year it was -4.60 D, and at 2 years it increased to -5.50 D. In contrast, the mean spherical equivalent refraction in the LASIK eyes at 3 months after surgery was -0.22 D and remained nearly stable until 1.5 years after surgery, when it was -0.50 D. More regression occurred when a large amount of corneal stromal tissue was removed. One out of four eyes that had more than 25% of its corneal tissue removed lost correction after 6 months for both ALK and LASIK. No ALK or LASIK eyes with a remaining corneal thickness of 310 microns or more had regression of the refractive result after 6 months. CONCLUSIONS: Both ALK and LASIK can reduce moderate and high myopia. The safety and long-term stability of LASIK is better than that for ALK. Although both procedures take advantage of lamellar keratoplasty techniques, the LASIK technique minimizes the depth of ablation while maximizing optical zone size which results in more accurate correction and better long-term stability, the latter depending primarily on the amount of corneal stromal tissue removed.
Adolescent↗
Two-year follow-up of laser in situ keratomileusis for hyperopia.
PURPOSE: To evaluate excimer laser in situ keratomileusis (LASIK) for hyperopia and its predictability. METHODS: We performed a retrospective study of 100 eyes that had LASIK for hyperopia to assess predictability and long-term stability of refractive results. The Chiron Automated Corneal Shaper was used to create the flap and the Keracor 117CT Chiron-Technolas excimer laser with the plano-scan program was used to ablate all corneas. RESULTS: Mean baseline spherical equivalent manifest refraction was +4.50 +/- 1.73 D (range, +1.25 to +8.50 D). Six months after LASIK, mean manifest spherical equivalent refraction was +0.72 +/- 1.87 D (range, -1.75 to +2.50 D), at 1 year, +0.88 +/- 1.73 D (range, -1.25 to +2.50 D), and at 2 years, +0.85 +/- 1.74 D (range, -0.50 to +2.75 D). Two years after LASIK, 45 eyes (74%) were within +/-1.00 D of intended correction and within +/-1.00 D of emmetropia. Uncorrected visual acuity was 20/40 or better in 50 eyes (82%) at 2 years; 29 eyes (37%) saw 20/20 or better. Undercorrection occurred more frequently in eyes with preoperative keratometric power of more than 45.00 D, when ablation zones less than 6 mm were used and when higher amounts of hyperopic correction were required. CONCLUSION: LASIK with the Keracor 117CT excimer laser appears to be an effective and safe procedure to correct hyperopia. Preoperative keratometric power, amount of hyperopia, and ablation zone diameter affect the efficacy and long-term stability of the procedure.
Adult↗