Dynamics in Number of Microaneurysms in Patients with Diabetic Retinopathy as an Indicator of the Risk of Macular Edema

Kresiun N. V.

METHODS AND METHODOLOGIES

Scentific article

The research presented was aimed to evaluate the dynamic changes in number of microaneurysms (MA) in the macula by applying the method designed to assess the results of screening diagnostics and based on involving multiresolution texture gradient as well as to prove the prognostic value of this indicator in patients who developed macular edema (MA). The study involved 279 patients, 253 of them were subjected to re-examination in a half of the year. 235 patients passed through re-examination in a year and a half. The insertion criteria of the study were the following: diagnosis of diabetes mellitus type II, age ranged from 40 to 75, mild non-proliferative diabetic retinopathy (DR) (20-35 levels according to ETDRS classification), no clinical manifestations of macular edema, which vision correction made up over 95 (in case of letter standard size 20/ 25 for visual acuity assessment by ETDRS and refraction less than 5 diopters. In a term of a year since the re-examination 23 patients were observed to demonstrate the transition of the severity of clinical manifestations into moderate non-proliferative form of DR (43 by ETDRS scale). One patient developed more severe affections manifested by moderately marked proliferative DR (65 B). The patients who did not demonstrated such a transition the average number was 3,10 ± 0,11, while in the patients who had more severe affections the average number made up 6,64 ± 0, 42. The obtained results testify that in terms of total number of MA cases, rate of new MA formation and rate of gen- eral dynamics of MA increase, there are evident differences between the groups of patients who demonstrate the occurrence of ME in a half-year and patients who do not develop ME. The positive prognostic parameter amounted to 41. 4 %, while the negative one was 94. 3 %, which is indicative of the fact that the low rate of dynamic changes (increase) of MA cases is associated with the low probability of ME development during the next period of observation (one year). It is necessary to remark that the obtained results are indicative of the fact that formation and regression of MA is an important informative sign of progressive development of DR in patients who have suffered from type II diabetes mellitus for a long time. At the same time, it is necessary to emphasize that the performed research gave the possibility to establish that the value of MA, both the total number of cases and the rate of formation, as well as the regressive development is an objective criteria for assessing the condition of DR and its further progression. Accordingly, it is reasonable to consider that the higher is the rate of MA “circuit”, the more probable is the forma- tion of edematic changes in its macular zone. The researches testify that the rate exceeding 9 is predicative as to the assessment of ME occurrence in patients with diabetes mellitus during the next 1. 5 year from the moment of determining the corresponding parameter. In our research, the rate which was predicative during the next year as to the development of ME turned out to be slightly higher (by one third) and amounted to 12. 0. Performed clinical investigations proved that the technology of MA diagnostics, proposed by us, is more effective than others. In this context, it is possible to assume that higher rates which were detected in present research can be partially explained by higher effectiveness of the applied diagnostic algorithm. In the group with high risk of developing ME, in contrast to patients with lower risk, significant divergences in the rates of glycohemoglobin content and the width of retina were detected. Investigations which were performed on the biocytocultures testify that hyperglycemia results primarily in glycosylation of basal membrane of retinal capillaries which leads to formation of final products that decrease the adhesion of pericytes and inhibit their pro- liferation. Thus, the loss of pericytes together with increasing of hydrostatic pressure is the most essential factor which leads to accumulation of exudates and thickness of retina as a sign of ME. So the correct control of glycemia permits to prevent the progress of delayed complications as ME or hemorrhea in the vitreous body and to decrease the risk for MA development at the early stage of DR formation. Conclusions. Formation of macular edema is preceded by high rate of development and regression of microan- eurysms which should be defined as a risk factor of progressive development of diabetic retinopathy. The application of method of broad-scale gradient analysis of digital images of fundus of the eye enables us to effectively diagnose MA and determine the risk of ME development.

diabetic retinopathy, microangiopathies, macular edema

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