The purpose of this study was to evaluate functional and funduscopic outcomes amongst patients receiving multiple treatments with macular laser photocoagulation for clinically significant diabetic macular edema. A record review was conducted of patients who had multiple macular laser treatments for diabetic macular edema. As part of routine follow-up for diabetic macular edema, visual acuity and funduscopic findings were assessed before a given laser treatment and at 6 months afterwards. The study included 64 eyes from 41 patients. There was no statistically significant difference between the proportion of eyes that showed funduscopic improvement after treatment 1 versus the proportion of eyes that improved after subsequent treatments. For the first laser treatment, 44 of the 64 eyes (69%) showed funduscopic improvement in edema. 35/64 (55%) of eyes showed improvement after the second treatment (p=0.15); 29/40 (72.5%) eyes showed improvement after the third treatment (p=0.85); 15/18 (83.3%) eyes showed improvement after treatments[greater than or equal to]4 (p=0.36). Similarly, in terms of visual acuity outcomes, there was no statistically significant difference between the proportion of eyes with preserved visual acuities after treatment 1 compared to repeat treatments. This study found that the majority of eyes that receive re-treatment after initial laser therapy will respond with an improvement in macular edema.

Thesis (Ph. D.)--University of Texas at Austin, 1998. / Vita. Includes bibliographical references (leaves 176-183). Available also in a digital version from Dissertation Abstracts.

An investigation of the temperature response and corresponding lesion growth resulting from in vivo interstitial laser photocoagulation was performed in order to test the applicability of Arrhenius theory. The irradiations were performed in vivo in rabbit muscle for various exposures at 1.0W using an 805 nm diode laser source coupled to an optical fibre with a pre-charred tip, thereby forcing it to function as a point heat source. Temperature responses were measured using a five-microthermocouple array along a range of radial distances from the point heat source. Each temperature profile was fitted with a curve predicted by the Weinbaum-Jiji bioheat transfer equation. The lesions were resected 48 hours after irradiation and the boundary of thermal damage resulting in necrosis was determined histologically. Numerical integration of the Arrhenius integral using temperature-time data at the lesion boundary produced corresponding activation energy and pre-exponential factor pairs (Ea , a) consistent with reported values for various other endpoints and tissue types. As well, theoretical predictions of the lesion growth from Arrhenius theory agreed well with experimental results. However, the thermal parameters, which are generally assumed to be constant when solving the bioheat transfer equation, were found to vary with radial distance from the source, presumably due to a dependence on temperature. / Thesis / Master of Science (MS)

<p>Dijabetesna retinopatija je među vodećim uzročnicima stečenog slepila, kako u razvijenim zemljama, tako i zemljama u razvoju. Dijabetesna retinopatija je jedna od<br />najče&scaron;ćih komplikacija Dijabetes Mellitus-a. U sklopu dijabetesne retinopatije jedan od najranijih razloga koji dovodi do pada vidne o&scaron;trine je dijabetični makularni edem (DME). Pad vidne o&scaron;trine kod pacijenata sa dijabetesom naru&scaron;ava njihov kvalitet života i umanjuje radnu sposobnost. Dosada&scaron;nji oblik lečenja laserfotokoaguacijom makule, nije dao zadovoljavajuće rezultate. U novije vreme sve vi&scaron;e je zastupljeno farmakolo&scaron;ko lečenje edema koje podrazumeva intrvitrealnu aplikaciju lekova iz grupe inhibitora vaskularnog endotelnog faktora rasta (VEGF inhibitori), koji dovodi do stabilizacije zidova krvnih sudova.&nbsp;<br />Cilj ove studije je da se ispita efikasnost lečenja DME uz pomoć intravitrealno aplikovanih lekova iz grupe inhibitora vaskularnog endotelnog faktora rasta u odnosu na konvencionalno do sada priznato lečenje laserfotokogulacijom makule.&nbsp;<br />Efikasnost lečenja je procenjivana na dva načina: anatomski, na osnovu smanjenja centralne makularne debljine izražene u &mu;m, merene metodom optičke koherentne tomografije, i funkcionalno, na osnovu pobolj&scaron;anja vidne o&scaron;trine koja je izražavana u log MAR jedinicama. U ovoj prospektivnoj, randomiziranoj kliničkoj studiji sa minimumom praćenja od 6 meseci, u eksperimentalnoj grupi tretiran je 51 pacijent,<br />odnosno 84 oka aplikacijom bevacizumaba (anti VEGF agens) u dozi od 1,25 mg, sa ili bez dodatnog laser tretmana.&nbsp;<br />Uz prosečno 2,46 inekcije postignuta je prosečna redukcija centralne makularne debljine od 139,15 &mu;m.&nbsp; Dobijene vrednosti su nakon svake aplikovane doze su značajno bolje u odnosu na početnu. Edemi sa većom centralnom makularnom debljinom su zahtevali tretman sa većim brojem inekcija. Kod većih edema je postignuta i veća redukcija centralne makularne debljine. U odnosu na vidnu o&scaron;trinu u eksperimentalnoj grupi postignuto je pobolj&scaron;anje od 0,135 log MAR jedinica. Efekat lasera kao samostalne terapije u kontrolnoj grupi (50 pacijenata, 92 oka) nije bio<br />značajan ni u pogledu smanjenja centralne makularne debljine kao ni na osnovu pobolj&scaron;nja vidne o&scaron;trine. Tretman bevacizumabom samostalno ili u kombinaciji sa laserom je efikasniji u tretmanu DME u odnosu na konvencionalni tretman laserfotokoaguacijom koji potvrđeno dovodi do stabilizacije stanja. Značaj ove studije je potvrda efikasnosti i bezbednosti jednog novog oblika lečenja koji samostalno ili u kombinaciji sa laser tretmanom predstavlja novi protokol lečenja dijabetičnog makularnog edema.</p> / <p>Diabetic retinopathy is among the leading causes of acquired blindness in developed countries, as well as in developing countries. Diabetic retinopathy is one of the most frequent Diabetes Mellitus complications. Within diabetic retinopathy, diabetic macular edema (DME) is one of the earliest causes of the loss of visual acuity. Impaired vision causes decline in life quality in diabetic patients and it decreases their<br />working ability. Up to this date, laser photocoagulation treatment has not given<br />satisfactory results. Recently, new promising treatment forms have emerged, including the intravitreal application of vascular endothelium growth factor (VEGF inhibitors), which lead to stabilization of the vessel wall. The aim of this study is to evaluate the efficacy of DME treatment consisting of intravitreal&nbsp; VEGF inhibitor application alone or as a part of combined treatment (intravitreal VEGF inhibitor plus laser photocoagulation) compared with conventional laser treatment alone. The effect of treatment was evaluated according to morphological parameters by measuring central macular thickness (CMT) in &mu;m with optical coherence tomography, and according to functional parameter by visual acuity in log MAR scale. In this prospective randomized clinical trial, with minimum follow up of 6 months, in experimental group 51 patient, or 84 eyes were treated with bevacizumab (VEGF inhibitor) in 1.25 mg dosage, alone or in combination with laser. The mean reduction in was 139.15 &mu;m, which was achieved with 2.46 doses on average. The difference between the final and initial CMT values after each dos age was tatistically significant.<br />Edemas with high central macular thickness required high number of intraviteal<br />aplicatons and the reduction was higher. In our study, mean visual acuity improved significantly in 0.135 log MAR. In control group (50 patient, 92 eyes) treated with laserphotocolagulation alone, the effect on visual acuity and central acular thickness was not statistically significant. The treatment with bevacizumab alone or in combined<br />treatment is more effective in treating DME than conventional macular laser treatment alone, from both - anatomical and functional perspective. The importance of this study is confirmation of the efficacy and safety of a new form of treatment and the introduction of a new protocol for the treatment of diabetic macular edema.</p>