Age-related ultrastructural and monoamine oxidase changes in the rat optic nerve.

The aim of this paper is to study the morphology and the distribution of the monoamine oxidase enzymatic system in the optic nerve of 4 month-old Wistar (young) and 28 month-old Wistar (old) rats. The optic nerve was harvested from 20 young and old rats. The segment of optic nerve was divided longitudinally into two pieces, each 0.1 mm in length. The first piece was used for transmission electron microscopy. The second piece was stained with histochemical reaction for monoamine oxidase. The agerelated changes in the optic nerve of rats include micro-anatomical details, ultrastructure and monoamine oxidase histochemical staining. A strong decrease of the thin nerve fibers and a swelling of the thick ones can be observed in optic nerve fibers of old rats. Increased monoamine oxidase histochemical staining of the optic nerve of aged rats is well demonstrated. The increase of meningeal shealth and the decrease of thin nerve fibers of the optic nerve in old rats are well documented. Morphological, ultrastructural and histochemical changes observed in optic nerve fibers of the old rats show a close relation with aging.

Occlusion of retinal capillaries caused by glial cell proliferation in chronic ocular inflammation.

The inner blood-retinal barrier is a gliovascular unit in which glial cells surround capillary endothelial cells and regulate retinal capillaries by paracrine interactions. During chronic ocular inflammation, microvascular complications can give rise to vascular proliferative lesions, which compromise visual acuity. This pathologic remodelling caused by proliferating Müller cells determines occlusion of retinal capillaries. The aim of the present study was to identify qualitative and quantitative alterations in the retinal capillaries in patients with post-traumatic chronic ocular inflammation or post-thrombotic vascular glaucoma. Moreover, we investigated the potential role of vascular endothelial growth factor (VEGF) and pro-inflammatory cytokines in retinal inflammation. Our electron microscopy findings demonstrated that during chronic ocular inflammation, thickening of the basement membrane, loss of pericytes and endothelial cells and proliferation of Müller cells occur with irreversible occlusion of retinal capillaries. Angiogenesis takes place as part of a regenerative reaction that results in fibrosis. We believe that VEGF and pro-inflammatory cytokines may be potential therapeutic targets in the treatment of this disease although further studies are required to confirm these findings.

A novel index for predicting macular thickening after cataract surgery.

PURPOSE: In this study, we tried to investigate weather or not the preoperative anterior chamber depth, the lens thickness (LT) and the relation between these variables by the ratio (K) of the distance from the corneal peak to the posterior side of the lens (A) (K = A/LT) could be predictive for a surgically induced foveal thickening following uneventful cataract surgery in normal, emmetropic eyes. PATIENTS AND METHODS: A total amount of 45 eyes, 25 females and 20 males, were enrolled in this study and underwent uncomplicated phacoemulsification under topical anesthesia. A complete ophthalmological examination was performed preoperatively, including refraction, best corrected visual acuity, slit-lamp examination, biometry and optical coherence tomography of both eyes. These examinations, with the exception of the biometric examination, were repeated one day, one week and four weeks after surgery. RESULTS: The K ratio was positively correlated with the macular thickness changes after cataract surgery. The Pearson correlation analysis of K ratio and foveal thickness changes was 0.792 (y = 36.457x - 52.558, R2 = 0.6266). CONCLUSIONS: A novel ratio that incorporates preoperative ocular parameters has been described. It could be easily measured in a clinical setting, and appears to be strongly predictive for macular thickening following cataract surgery. Of course, further studies enrolling a larger amount of patients are necessary in order to confirm these preliminary data.

Spontaneous closure of bilateral full thickness macular holes without surgery: an eleven-year follow-up.

PURPOSE AND METHOD: To present a 60-year-old woman affected by bilateral full thickness macular hole, showing without surgery a spontaneous resolution of the disease in both eyes that remains unchanged during an eleven-year follow-up. To our knowledge, this clinical case is uncommon as no similar reports with such a long follow-up have been published in the scientific literature at this time. RESULTS AND CONCLUSIONS: A spontaneous and bilateral closure of full thickness macular holes was detected, as a consequence of a complete posterior vitreous detachment documented by optical coherence tomography images. An initial reduction up to a complete resolution of the central macular scotoma was also observed by performing scanning laser ophthalmoscope microperimetry. Both these anatomical and functional results did not change during the whole period of follow-up. According to this study, the release or the weakening of the vitreous tractions at the foveal edges seems to play a key role in the spontaneous resolution of macular holes in not surgically treated patients.

Hypotensive effect of pilocarpine after argon laser trabeculoplasty.

The exact mechanism of action of argon laser trabeculoplasty (ALT) has only been presumptively proposed. There are two hypotheses of action of ALT: the first is the mechanical theory and the second is centered on the possibility of laser-induced modifications of trabecular cells. The goal of our investigation was to verify if pilocarpine determines a decrease of intraocular pressure mainly by a mechanical stretching of the meshwork; if pilocarpine could lower intraocular pressure after ALT; and thus if the mechanism of action of laser treatment could mainly be attributable to a mechanical strain of the trabecular meshwork. Twenty-one patients affected with primary open angle glaucoma had been recruited for the study. Twenty-one eyes underwent trabeculoplasty. All the patients were followed for 6 months. Statistical analysis of the data revealed that pilocarpine was not able to induce a further decrease of intraocular pressure after trabeculoplasty. Moreover, the maximum decrease of intraocular pressure induced by pilocarpine before laser treatment was not statistically different from the tensional values after ALT. The results of the present investigation suggest that the mechanism of action of trabeculoplasty is probably attributable to a mechanical stretching of the trabecular meshwork and the results show the inefficacy of pilocarpine after laser treatment in the management of glaucomatous patients.

Optical coherence tomography.

The optical coherence tomograph is a new, noninvasive technical device that can obtain cross-sectional, high-resolution images-optical coherence tomographs (OCT)-of the retina. This instrument permits an accurate evaluation of various macular and chorioretinal pathologies and the early detection of glaucomatous damage. Images of the retina are obtained similar to ultrasound B-scan, with 10-microm longitudinal resolution. Because the OCT operates with a near-infrared wavelength (about 840 nm), the examination is of minimal discomfort for the patient. OCT examination is indicated in cases of macular pathologies such as vitreoretinal interface syndrome, in the early detection and quantitative assessment of macular edema, and in the evaluation of a glaucomatous damage by measuring the retinal nerve fiber layer thickness. The future role of this instrument and its applications for clinical diagnosis depend on the future improvement and updating of the software.

Morphological evaluation of full-thickness idiopathic macular holes by optical coherence tomography.

PURPOSE: To assess the efficacy of optical coherence tomography (OCT) for the morphological evaluation of idiopathic full-thickness macular holes and for detecting any morphological changes with time. METHODS: Serial sagittal tomographs through the macula were taken by OCT in a consecutive series of 34 eyes of 34 patients with diagnosis of idiopathic full-thickness macular hole. The patients were divided into two groups on the basis of "recent" (group 1, 25 patients) or "not-recent" (group 2, 9 patients) onset of symptoms related to the macular hole. Fourteen of the 25 patients in group 1 and all nine in group 2 underwent vitrectomy. The 11 in group 1 who refused surgery were observed by OCT examination with follow-up from 6 to 13 months. RESULTS: In most eyes OCT scans revealed two different anatomical features of macular holes depending on the time of onset of symptoms. Eleven of the 14 "recent-onset" holes that underwent surgery showed "sharp", undermining edges at preoperative OCT; the other three had "rounded" edges. Seven of the nine eyes operated for long-standing full-thickness macular holes had preoperative "rounded" edges, while the edges in the remaining two eyes were "sharp". OCT of eight of the 11 non-operated eyes in group 1 showed a morphological evolution of the macular hole edges from a "sharp" to a "rounded" contour and an increase in the diameter of the hole. CONCLUSIONS: OCT can help in the morphological evaluation of idiopathic full-thickness macular holes and in the detection of morphological changes with time.

Changes in vital signs during cataract phacoemulsification by using peribulbar or topical anesthesia.

AIMS: To compare changes in vital signs and pain level experienced by patients during phacoemulsification and foldable intraocular lens (IOL) implantation using either topical/intracameral or peribulbar anesthesia. MATERIALS AND METHODS: In this prospective, parallel-group clinical study 46 consecutive patients (mean age 72.9 +/- 8.1 years) undergoing cataract surgery were randomized to receive topical/intracameral (group1) or peribulbar (group 2) anesthesia. Systolic, diastolic and mean blood pressures, hearth rate, oxygen saturation and pain level were recorded before and during the anesthesiological procedure and thereafter during each surgical step. RESULTS: Diastolic blood pressure during phacoemulsification and after surgery as well as mean arterial pressure after surgery were significantly higher in group 1 compared to group 2. Variability of systolic and mean arterial pressures across the study phases was significantly higher in group 2 compared to group 1. A significantly higher percentage of patients in group 2 compared to group 1 (35.3% vs 3.4%, p=0.007) showed a heart rate reduction greater than 10% from the anesthesiological to the following surgical phase. Higher incidence of moderate pain in group 2 was reported during the anesthesiological procedure (64.7% vs 3.4%, p<0.00001) while higher incidence of moderate pain was reported in group 1 during phacoemulsification (31% vs 5.9%, p=0.047) and IOL implantation (21.7% vs 2.2%, p=0.02). DISCUSSION: Our short study seems to recommend the use of topical/ intracameral anesthesia for cataract surgery due to more stable heart rate, diastolic and mean blood pressures. However, further studies enrolling a higher amount of patients are necessary to confirm our preliminary data.

Retinal detachment after clear lens extraction in 41 eyes with high axial myopia.

PURPOSE: Clear lens extraction is a surgical procedure to correct high axial myopia. The authors explain how this technique may lead to serious vitreoretinal complications. METHODS: The study included 41 eyes of 39 patients aged 25 to 58 years (mean, 37.5 years) with high axial myopia (14-29 diopters; mean, 19.5 diopters) operated on for retinal detachment after clear lens extraction. Retinal detachment occurred 1 month to 4 years after lens extraction, except for two eyes that also had intraoperative choroidal hemorrhages. RESULTS: Twenty-six of the 41 eyes had undergone 360 degree prophylactic retinopexy on preequatorial areas; in four eyes, the retinal breaks occurred along the edge of the prior circumferential photocoagulation. Seventeen eyes exhibited proliferative vitreoretinopathy of various grades. The retina was reattached in 36 eyes. Only nine eyes achieved final visual acuity of 20/60 or better. CONCLUSIONS: Although the authors do not report the actual incidence of retinal detachment after clear lens extraction, they indicate that potentially blinding complications can occur after this surgical procedure, despite prophylactic treatments.

Evaluation of primary surgical procedures for retinal detachment with macular hole in highly myopic eyes: a comparison [corrected] of vitrectomy versus posterior episcleral buckling surgery.

PURPOSE: To evaluate postoperative outcomes between pars plana vitrectomy (PPV) and posterior episcleral buckle procedure (PEBP) in myopic eyes with retinal detachment (RD) and macular hole (MH). DESIGN: Retrospective nonrandomized comparative interventional trial. PARTICIPANTS AND INTERVENTION: The study included 30 phakic, highly myopic eyes (from 19-30 negative diopters) of 30 patients with an RD and MH. The patients were divided into two groups: They were assigned to PPV (15 eyes, group A) or to PEBP (15 eyes, group B). No significant (P > 0.01) differences in preoperative visual acuity (VA) between group A and group B eyes were found. Follow-up was 12 months. MAIN OUTCOME MEASURES: Anatomic attachment of the retina was determined, and VA was measured. RESULTS: Retinal reattachment was obtained on 11 of 15 (73.3%) eyes of group A and on 14 of 15 (93.3%) eyes of group B. In group A eyes the VA was substantially unmodified after surgical treatment, whereas in group B eyes the VA observed after surgical treatment increased significantly (P < 0.001) with respect to the preoperative values. CONCLUSIONS: PEBP resulted in better postoperative anatomic and functional results compared with PPV in eyes with extreme degrees of myopia, pronounced posterior staphyloma, and posterior vitreous schisis affected with RD caused by MH.