Nenad Petrovic

Determination of Real Clearances Between Cycloidal Speed Reducer Elements by the Application of Heuristic Optimization

The actual cycloidal speed reducer elements differ from their theoretical ideal due to existing tolerances; therefore, the cycloid disc behaves like a corrected one. This study is oriented towards determining contacts in corrected cycloid speed reducer profiles from the aspect of geometry. Based on this geometry, an objective function was developed for the optimization with some limitations. Heuristic optimization was used to determine the position of the cycloidal drive elements when a contact was established and, consequently, to determine clearances in other places. Some limitations were set so that the model could reflect a real contact. In this study, a TLBO algorithm was used for the optimization of a cycloidal speed reducer. Clearances were analysed for different correction values of the cycloid disc profile of an actual cycloidal drive and the optimization procedure was presented. The results provide a real picture of the contact in the presence of inevitable machining tolerances.

Nanotechnology in Ophthalmology

Nanotechnology has already been used for the purpose of the measurement as well as treatment of great number of ophthalmological diseases. The applications of Nanotechnology to Ophthalmology refer to the following: delivery of drugs, peptides and genes, biomedical imaging and diagnostics of distinct disorders of the eye, study of pathogenesis of the eye disease. Regenerative nanomedicine is considered to be a prospective approach for treating retinal degenerations and the second cranial nerve regeneration. Our manuscript included possible different application for ophthalmological drug using nanotechnology. Also, we described the importance of nanotechnology for imaging, diagnostic and monitoring of ocular diseases. Nanobiotechnology for glaucoma treatment, as well as nanoparticles for gene delivery therapy of retinal degenerative disease, is most attractive approach for the ophthalmological treatment.

The Efficacy of a Posterior sub-Tenon’s Capsule Triamcinolone Injection in Patients with Non-infectious Intermediate Uveitis and Posterior Uveitis

Abstract To investigate the efficacy of a posterior sub-Tenon’s capsule triamcinolone injection for treating eyes with non-infectious posterior and intermediate uveitis. A total of 31 eyes from 20 patients with non-infectious posterior uveitis and 18 eyes from 10 patients with non-infectious intermediate uveitis that inadequately responded to treatment with systemic corticosteroids and second-line immunosuppressive agents were enrolled in the study. All patients received a posterior sub-Tenon’s injection of 20 mg/ml triamcinolone. The parameters we examined included the following: best corrected visual acuity, central foveal thickness, fluorescein angiography score and intraocular pressure. The mean best corrected visual acuity was significantly improved from the control visit, 0.15±0.30 logMAR (Snellen equivalent 0.7), compared to the baseline measurements, 0.60±0.30 logMAR (Snellen equivalent 0.25; P<0.05). The mean central foveal thickness (CFT) and the mean score for fluorescein angiography (FA) were significantly decreased from the baseline (CFT: 320±34 μm; FA mean score: 5.9±1.9) compared to the twelve-week control visit (CFT: 235±30 μm; FA mean score: 1.2±1.1; P<0.001). Five eyes had intraocular pressure spikes that required a topical anti-glaucomatous treatment. A posterior sub-Tenon’s injection of triamcinolone can significantly improve visual acuity and decrease macular oedema in patients with non-infectious posterior and intermediate uveitis. Complications were minimal, and there were no eyes that required surgical treatment for elevated intraocular pressure. The results suggest that the posterior sub-Tenon’s injection of triamcinolone is an important form of therapy for non-infectious posterior and intermediate uveitis.

Tear Film Stability in Patients with Pseudexfoliation

Abstract Pseudoexfoliation syndrome is an age related disorder, characterized by abnormal fibrous fiber production and accumulation in different visceral organs as well as in the eye and periocular tissues. Hystological examination recorded the presence of the pseudoexfoliation in the conjunctiva, and they can disturb the accessory lacrimal gland and goblet cell function. This can explain tear film instability in patients with pseudoexfoliations. In our study, we examined the tear film stability in patients with and without pseudoexfoliation, using Schirmer test and tear break up time test. Our results indicated that patients with pseudoexfoliation had lower values of Schirmer and tear break up time tests than patients without it. Pseudoexfoliation is the main reason for the instability of the tear film, because of its negative impact on the conjucntival goblet cells. In conclusion, ophthalmologists must have these data on their mind in the process of the pseudoexfoliation glaucoma treatment and controlling.

Quantitative Analysis of Uveitis Macular Edema in Multiple Sclerosis Patients Receiving Deep Posterior Sub-Tenon Triamcinolone Acetonide Injection

Aim: We aimed to analyze the effects of adjunctive posterior sub-Tenon capsule triamcinolone acetonide injection in the treatment of intermediate uveitis macular edema in multiple sclerosis patients that could not be controlled by systemic corticosteroid medications and immunomodulators. Methods: The study included 30 eyes of 25 patients with multiple sclerosis who received a posterior sub-Tenon injection of 40 mg/mL triamcinolone acetonide. Parameters monitored for therapy efficiency were best-corrected visual acuity, intraocular pressure, central foveal thickness (CFT), and fluorescein angiography (FA) scores. Results: Mean best-corrected visual acuity was significantly improved at the control visit 0.15 ± 0.10 versus baseline 0.40 ± 0.20 logMAR (p < 0.05). Six eyes showed intraocular pressure spikes requiring topical antiglaucomatous treatment. Mean CFT and FA scores were significantly decreased versus baseline (CFT: 345 ± 50 μm; FA score: 3.4 ± 1.0) compared with the 12-week control visit (CFT: 219 ± 35 μm; FA score: 1.6 ± 1.1; p < 0.001). Conclusion: Posterior sub-Tenon injection of triamcinolone acetonide significantly improved visual acuity and decrease macular edema in patients with intermediate uveitis associated with multiple sclerosis.

Relentless placoid chorioretinitis: A case report

Introduction Relentless placoid chorioretinitis is an entity which belongs to the group of an atypical intermediate form of primary inflammatory choriocapillaropathies, resembling both acute posterior multifocal placoid pigment epitheliopathy and serpiginous choroiditis, but the retinal distribution and clinical course are not the same. Because of this similarity this entity was termed “AMPPiginous”. This entity was first described by Jones et al. in 2000. The aim of our case report is to present a very specific case where the clinical course was progressive, with loss of vision in the affected eye. Case Outline A 31-year-old man, with no previous ophthalmic diseases, was hospitalized at the Clinic of Ophthalmology, Clinical Center Kragujevac, because of a reduction of vision in the right eye, and scotoma and metamorphopsia in the left eye. The clinical course of retinal lesions in the left eye resembled the changes observed in acute posterior multifocal placoid pigment epitheliopathy, and the right eye changes were between acute posterior multifocal placoid pigment epitheliopathy and serpiginous choroiditis. The diagnosis of relentless placoid chorioretinitis was confirmed after clinical, laboratory, immunological, virological, and angiography examinations. Conclusion The progressive clinical course of the disease, complemented by multimodal imaging and extensive laboratory diagnostics, has led us to the diagnosis of relentless placoid chorioretinitis. The combined anti-inflammatory and immunomodulatory therapy led to the stabilization of visual acuity of the left eye as opposed to the right, where there has been no recovery.

[Evolution of cataract surgery: smaller incision--less complications].

BACKGROUND/AIM Cataract surgery has become one of the safest procedures in medicine thanks to advances in technology and surgical techniques. Although minimal, we still witness different complications. The aim of this study was to compare visual outcome and complication rate in different techniques of cataract surgery, ie in cataract surgeries with various corneal incision width. METHODS The study included 3,457 consecutive patients, ie 4,670 eyes that had undergone cataract surgery. The used surgical techniques were: extracapsular cataract extraction, phacoemulsification/forceps IOL implantation, phacoemulsification/injector IOL implantation, microincision cataract surgery (MICS). Patient follow up was 6 months. Patients were evaluated for: visual aquity, corneal astigmatism, cellular reaction in the anterior chamber, IOL position. RESULTS Uncorrected visual aquity 30 days postoperatively was > or = 0.5 in 30% of the eyes - ECCE; 54.7% of the eyes - phacoemulsification/forceps IOL implantation; 63.0% of the eyes - phacoemulsification/injector IOL implantation; 5/8 of the eyes - MICS. Endophthalmitis was detected in 0.15% of the eyes - ECCE and 0.1% of the eyes - phacoemulsification/forceps IOL implantation. In eyes with phacoemulsification/injector IOL implantation or microincision cataract surgery (MICS) there were no cases of endophthalmitis. After a 6-month period intraocular lens were dislocated in 7.2% of the eyes - ECCE, and 0.6% of the eyes - phacoemulsification/PMMA IOL. There was no IOL dislocation in other surgical techniques. CONCLUSION Shorter corneal incision implies less complications, less operative trauma, faster visual rehabilitation and better visual outcome.

Comparison of primary medicament therapy effects and primary argon laser trabeculoplasty on regulation of intraocular pressure and stability of perimetry findings in open angle glaucoma

INTRODUCTION/AIM Argon Laser Trabeculoplasty (ALT) is a recognized method for reducing intraocular pressure (IOP) in patients with open angle glaucoma. The aim of this study was to compare the effects of primary medicament therapy and primary ALT on IOP regulation and stability of perimetry findings. METHODS A total of 50 eyes of 35 patients were treated with primary ALT while 50 eyes of 36 patients were treated with primary medicament therapy with 0.5% timolol with 20, 0.005% latanoprost 18 and with 2% dorzolamid 12 eyes. IOP was controled at 3 months, and the visual field at 6 months during a 30-month follow-up period. RESULTS In the first 24 months of follow-up there was no statistically significant difference in percentage of eyes with successfully regulated IOP. At 27th and 30th month, in the group primarily treated with medicaments a statistically significant higher percentage of successfully regulated IOP was observed in 98%, and 96% of the eyes, respectively, while in the group primarily treated with ALT the decline in the percentage of successfully regulated IOP was observed in 78% and 76% of the eyes, (chi2-test, p = 0.002, p = 0.140). Both therapy groups showed stability of perimetry findings without statistically significant difference in the values of mean deviation (MD) index until the end of the monitoring period. The dynamics of change in MD index value showed a statistically significant greater decline in this parameter in subjects who had been primarily treated with medications during the last six months of follow-up, (two-factor analysis of variance with a repeated measurement, factor of time x type of therapy, p = 0.030). CONCLUSION Primary ALT equally successfully regulates IOP and restores stability of perimetry findings in patients with open angle glaucoma like the primary medicament therapy.